Multiple intra-articular injections of autologous stromal vascular fractions for the treatment of multicompartmental osteoarthritis in both the tibiofemoral and patellofemoral joint: a single-blind randomized controlled study

BACKGROUND

Multicompartmental osteoarthritis (MOA) in both tibiofemoral and patellofemoral joints is a more commonly occurring, but neglected, clinical condition, and we examined the short-term safety and efficacy of autologous stromal vascular fractions (SVFs) for MOA using a single-blind, prospective, randomized, placebo-controlled trial.

METHODS

Seventy MOA patients were recruited and randomly assigned to the SVF group and hyaluronic acid (HA) group (control group). The scores of visual analog scale, the Western Ontario and McMaster University Osteoarthritis Index, and the Samsung Medical Center patellofemoral scoring system were assessed and compared between the two groups 3, 6 and 12 months after treatment.

RESULTS

The SVF group had significantly better visual analog scale scores than the HA group at 6 and 12 months after treatment and had better Western Ontario and McMaster University Osteoarthritis Index scores than the HA group only at 6 months after treatment. For Samsung Medical Center patellofemoral scoring system of the patellofemoral joint, the SVF group had significantly better scores than the control group at all postoperative time points. The proportion of patients whose visual analog scale and Western Ontario and McMaster University Osteoarthritis Index scores were above the minimal clinically important improvement was higher in the SVF group than in the HA group in the majority of assessments. The improvement of bone marrow by SVF treatment was significantly better than that of the HA group as observed by pre- and postoperative Magnetic resonance imaging (MRI).

CONCLUSIONS

Multiple intra-articular injection of autologous SVF reduces pain and improves function in the short term in patients with early or midstage MOA. However, there was heterogeneity in the improvement of overall knee and isolated patellofemoral joint after treatment.

Tibial tuberosity-trochlear groove distance is significantly decreased by medial closing wedge distal femoral osteotomy

PURPOSE

While medial closing wedge distal femoral osteotomy (MCWDFO) has been used to address patella instability combined with valgus malalignment, its impact on patellofemoral parameters remains uncharted. Hence, this study seeks to establish a three-dimensional (3D) planning of MCWDFO and measure its effect on the tibial tubercle - trochlear groove distance (TTTG) through simulation and calculation.

METHODS

MCWDFO with a stepwise increment of one-degree varisation (1°-15°) was performed on 3D surface models of 14 lower extremities with valgus malalignment and 24 lower extremities with neutral alignment of the lower limb, resulting in a total of 608 simulations. Anatomic landmarks were employed to measure hip-knee-ankle angle (HKA), TTTG, and femoral torsion for each simulation. A mathematical formula was adopted to calculate TTTG changes following MCWDFO, and subsequently the mean simulated and calculated TTTG values were compared. Following a standardised protocol, MCWDFO was performed without rotational changes.

RESULTS

MCWDFO exhibited an almost linear reduction in TTTG, at a rate of approximately -1.05 ± 0.13 mm per 1° of varisation, demonstrating a strong negative correlation (R = -0.83; p < 0.001). Limb alignment did not exert an influence on TTTG change; however, it correlated with tibial plateau width. The mean difference between the simulated and calculated TTTG values amounted to 0.03 ± 0.03 mm per 1° varisation (p < 0.001).

CONCLUSION

The TTTG distance is linearly reduced by 1.05 mm for every 1° of varisation within the varus correction range of 0°-15° during MCWDFO. Patients with combined valgus and patellar instability may benefit from MCWDFO due to frequently pathological TTTG.

LEVEL OF EVIDENCE

Level III, descriptive laboratory study.

Anatomic Risk Factors for Patellofemoral Joint Instability: An Infographic as a Visual Learning Tool

Patellofemoral instability is a complex pathology with multiple risk factors, which affects mostly young females and may avert them from both activities of daily living and sports participation. Risk factors for instability include patella alta, trochlea dysplasia, abnormal lateral patellar tilt, and increased tibial tuberosity-trochlea groove distance. The knowledge of these anatomical abnormalities is the key to identifying the problem and succeeding in treating the patients.

Association between patellofemoral osteoarthritis with demographic features and anatomical variants of the knee in non-traumatic patients

BACKGROUND

Patellofemoral osteoarthritis (PFOA) is a common cause of knee discomfort and impairment, particularly among athletes. The development of PFOA has been associated with anatomical knee variations, such as trochlear dysplasia and patella alta. However, the relationship between these anatomical variants and the development of PFOA remains poorly understood. This study aimed to investigate the association between PFOA and knee anatomical variants in a cohort of patients.

METHODS

The study included 200 patients with PFOA and 200 healthy controls. In this study, we investigate the relationship of osteoarthritis with both anatomical variants and demographic characteristics. The participants underwent Magnetic resonance imaging (MRI) evaluation of the knee, and anatomical variants including trochlear dysplasia and patella alta were assessed. The severity of PFOA was also graded based on cartilage area and depth, as well as the bone marrow involvement and presence of osteophytes.

RESULTS

Statistically significant differences were observed between the two groups in terms of Tibial tuberosity-trochlear groove (TT-TG) distance, patella position, trochlear dysplasia, and Insall-Salvati ratio. The mean TT-TG distance, prevalence of alta patella position, and Insall-Salvati ratio were significantly higher in cases (P<0.001 for all), and cases had a higher incidence of trochlear dysplasia (P<0.001). There were no significant differences between cases and controls regarding patella baja.

CONCLUSION

Anatomical knee variants, including the TT-TG distance, trochlear dysplasia, and Insall-Salvati ratio, are significant risk factors for PFOA progression. The results also indicate that higher BMI and older age are significantly associated with more measures of MRI Osteoarthritis Knee Score (MOAKS) than demographic information. Among anatomical variants, a higher TT-TG distance and an increased grade of trochlear dysplasia show a significant relationship with more measures of MOAKS. Understanding the relationship between these factors has important clinical and research implications and can help inform the development of new treatments.

Should we recommend patellofemoral arthroplasties to patients?

Aims

With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

Methods

MEDLINE, EMBASE via OVID, CINAHL, and EBSCO were searched from inception to January 2022. Any study addressing surgical treatment of primary patellofemoral joint OA using second generation PFA and TKA in patients aged above 18 years with follow-up data of 30 days were included. Studies relating to OA secondary to trauma were excluded. ROB-2 and ROBINS-I bias tools were used.

Results

A total of nine studies were included, made up of four randomized controlled trials (domain 1) and five cohort studies (domain 2). PROMs and knee function specific scores developed for reporting TKA were unable to detect any difference between PFA and TKA. There was no significant difference in complications between PFA and TKA. PFAs were found to have a better postoperative range of motion.

Conclusion

TKA and PFA are both viable options for patients with primary PFJ OA. Over time, we have seen an emphasis on patient satisfaction and better quality of life. Recommending sacrificing healthy medial and lateral compartments to treat patellofemoral joint arthritis should be given further thought.

Assessment of Patellar Vascularity after Patellar Cartilage Restoration via Lateral Parapatellar Approach: Analysis Using Dynamic Contrast-Enhanced Magnetic Resonance Imaging

OBJECTIVE

Patellofemoral cartilage restoration procedures, including osteochondral allograft, particulated juvenile cartilage, and matrix-induced autologous chondrocyte implantation, have been shown to be effective treatments for patellofemoral cartilage lesions. However, concerns exist regarding disruption of the patellar vascular supply and secondary stabilizers of the patellofemoral joint during medial parapatellar approaches, especially when combined with a lateral release. A lateral parapatellar approach affords the possibility of avoiding disruption of the medial blood supply to the patella, while also allowing laterally-based soft tissue stabilization procedures. The purpose of this study was to investigate in vivo changes in patellar vascularity following patellofemoral cartilage restoration procedures performed via a lateral parapatellar approach via use of dynamic contrast-enhanced magnetic resonance (MR) imaging.

DESIGN

This study is a prospective case series of 5 adult patients undergoing patellofemoral cartilage restoration procedures via a lateral parapatellar approach with pre-operative and post-operative dynamic contrast-enhanced MR imaging to assess changes in patellar vascularity. Secondary outcomes included knee range of motion, need for revision surgery, and complications.

RESULTS

There was no significant post-operative difference in patellar vascularity in patients undergoing patellofemoral cartilage restoration procedures via a lateral parapatellar approach, as evaluated by qualitative MR imaging.

CONCLUSION

Our results suggest that a lateral parapatellar approach for cartilage restoration procedures may preserve patellar vascularity, while also allowing for lateral release to be performed through the same incision.

The effects of a two-week neuromuscular intervention on biopsychosocial variables in people with patellofemoral pain: an observational study

Introduction

Patellofemoral pain (PFP) is common and predominately affects active populations. Altered biomechanics and psychosocial variables have been reported in people with PFP, but the effects of neuromuscular exercise on these variables is unknown. We aimed to investigate changes in biopsychosocial measures following a two-week neuromuscular intervention in people with PFP.

Materials and Methods

We measured pain (visual analogue scale), function (Kujala), activity level (Tegner), psychological well-being (Orebro), lower-limb isometric strength (handheld dynamometry), three-dimensional (3D) lower limb kinematics, and surface electromyography (sEMG), in people with PFP. 3D lower-limb kinematics and sEMG were synchronously sampled during step-up, step-down, and overground running. All measures were repeated after participants had completed a two-week neuromuscular intervention consisting of three exercises completed once per day, five days per week.

Results

18 participants completed pre/post testing (60% females, mean age 30.6 years ±7.0, height 173.4cm ±10.4, mass 70.2kg ±12.4, symptom duration 39.0 months ±58.8), with three of 21 participants lost to follow-up. Across all clinical measures (muscle onsets, muscle activation and kinematics), the 95% bootstrapped confidence intervals (CI) of the mean difference contained the null hypothesis following the two-week neuromuscular intervention, indicating no significant differences.

Conclusion

A two-week neuromuscular intervention did not change biomechanical or psychosocial measures in people with PFP. Interventions with a longer duration or greater load magnitude are required to fully evaluate the biopsychosocial mechanisms of effect for exercise in people with PFP.

In Vivo Length Changes Between the Attachments of the Medial Patellofemoral Complex Fibers in Knees With Anatomic Risk Factors for Patellar Instability

BACKGROUND

Medial patellofemoral complex (MPFC) reconstruction plays an important role in the surgical treatment of patellar instability. Anatomic reconstruction is critical in re-creating the native function of the ligament, which includes minimizing length changes that occur in early flexion. Anatomic risk factors for patellar instability such as trochlear dysplasia, patella alta, and increased tibial tuberosity to trochlear groove (TT-TG) distance have been shown to influence the function of the MPFC graft in cadaveric studies, but the native length change patterns of the MPFC fibers in knees with anatomic risk factors have not been described.

PURPOSE

To describe the in vivo length changes of the MPFC fibers in knees with anatomic risk factors for patellar instability and identify the optimal attachment sites for MPFC reconstruction.

STUDY DESIGN

Controlled laboratory study.

METHODS

Dynamic computed tomography imaging was performed on the asymptomatic knee in patients with contralateral patellar instability. Three-dimensional digital knee models were created to assess knees between 0° and 50° of flexion in 10° increments. MPFC fiber lengths were calculated at each flexion angle between known anatomic attachment points on the extensor mechanism (quadriceps tendon, MPFC midpoint [M], and patella) and femur (1, 2, and 3, representing the proximal to distal femoral footprint). Changes in MPFC fiber length were compared for each condition and assessed for their relationships to morphologic risk factors (trochlear depth, Caton Deschamps Index [CDI], and TT-TG distance).

RESULTS

In 22 knees, native MPFC fibers were found to be longer at 0° than at 20° to 50° of flexion. Length changes observed between 0° and 50° increased with the number of risk factors present. In the central fibers of the MPFC (M-2), 1.7% ± 3.1% length change was noted in knees with no anatomic risk factors, which increased to 5.6% ± 4.6%, 17.0% ± 6.4%, and 26.7% ± 6.8% in the setting of 1, 2, and 3 risk factors, respectively. Nonanatomic patella-based attachments were more likely to demonstrate unfavorable length change patterns, in which length was greater at 50° than 0°. In patellar attachments, an independent relationship was found between increasing length changes and TT-TG distance, while in quadriceps tendon attachments, a trend toward a negative relationship between length changes and CDI was noted. All configurations demonstrated a strong relationship between percentage change in length and number of morphologic risk factors present, with the greatest influence found in patella-based attachments.

CONCLUSION

The MPFC fibers demonstrated increased length changes in knees when a greater number of morphological risk factors for patellar instability were present, which worsened in the setting of nonanatomic configurations. This suggests that the function of the intact MPFC in patients with anatomic risk factors may not reflect previously described findings in anatomically normal knees. Further studies are needed to understand the pathoanatomy related to these changes, as well as the implications for graft placement and assessment of length changes during MPFC reconstruction techniques.

CLINICAL RELEVANCE

MPFC length change patterns vary based on the number of morphologic risk factors for patellar instability present and should be considered during reconstructive procedures.

Association of patella alignment with cartilage relaxation times and self-reported symptoms in individuals with patellofemoral degeneration

To determine the cross-sectional and longitudinal associations of patella alignment with cartilage relaxation and patients' self-reported symptoms. Thirty participants with isolated patellofemoral joint (PFJ) degeneration (six males, 53.7 ± 9.3 years) and 24 controls (12 males, 47.6 ± 10.7 years) were included. Magnetic resonance assessment was performed to provide grading of structural abnormalities, cartilage relaxation times, and patella alignment. Self-reported symptoms were assessed using the self-administrated knee injury and osteoarthritis outcome score (KOOS). All participants were examined at baseline and 3 years. Statistical parametric mapping and Pearson partial correlation were used to evaluate the associations between patella alignment with cartilage relaxation times and self-reported symptoms, respectively. The analyses were performed between baseline (cross-sectional) as well as the baseline against 3 years (longitudinal). Results indicated that patella height and patella flexion were associated with T1ρ and T2 relaxation times at baseline (percentages of voxels showing significant correlation [PSV] = 10.1%-24.8%; mean correlations [R] = 0.34-0.36; mean p = 0.015-0.026). Furthermore, greater patella lateral alignment, lateral tilt, and lateral spin were associated with longer T2 times at 3 years (PSV = 11.0%-14.4%, R = 0.39-0.44, p = 0.017-0.028). Last, a higher patella was associated with a lower KOOS at baseline and at 3 years (R = -0.33 to -0.35). The study suggests that patella malalignment is a risk factor for worsening cartilage health, informing clinicians of a better rehabilitation program that targets PFJ degeneration.

Early patellofemoral cartilage and bone pathology in a rat model of noninvasive anterior cruciate ligament rupture

OBJECTIVE

Anterior cruciate ligament rupture (ACLR) is a risk factor for the development of post-traumatic osteoarthritis (PTOA). While PTOA in the tibiofemoral joint compartment is well-characterized, very little is known about pathology in the patellofemoral compartment after ACL injury. Here, we evaluated the extent to which ACLR induces early patellofemoral joint damage in a rat model.

METHODS

Adult female Lewis rats were randomized to noninvasive ACLR or Sham. Two weeks post-injury, contrast-enhanced micro-computed tomography (µCT) of femoral and patellar cartilage was performed using 20% v/v ioxaglate. Morphometric parameters of femoral trochlear and patellar cartilage, subchondral bone, and trabecular bone were derived from µCT. Sagittal Safranin-O/Fast-Green-stained histologic sections were graded using the OARSI score in a blinded fashion.

RESULTS

Cartilage and bone remodelling consistent with an early PTOA phenotype were observed in both femoral trochleas and patellae. ACLR caused osteophyte formation of the patella and pathology in the superficial zone of articular cartilage, including surface fibrillation, fissures, increased cellularity, and abnormal chondrocyte clustering. There were significant increases in thickness of patellar and trochlear cartilage. Loss of subchondral bone thickness, bone volume fraction, and tissue mineral density, as well as changes to patellar and trochlear trabecular microarchitecture, were indicative of catabolic bone remodelling. Several injury-induced changes, including increased cartilage thickness and trabecular spacing and decreased trabecular number were more severe in the patella compared to the trochlea.

CONCLUSION

The patellofemoral joint develops mild but evident pathology in the early period following ACL rupture, extending the utility of this model to the study of patellofemoral PTOA.

Change in Descriptive Kinematic Parameters of Patients with Patellofemoral Instability When Compared to Individuals with Healthy Knees-A 3D MRI In Vivo Analysis

BACKGROUND

Patellofemoral instability (PFI) leads to chronic knee pain, reduced performance and chondromalacia patellae with consecutive osteoarthritis. Therefore, determining the exact patellofemoral contact mechanism, as well as the factors leading to PFI, is of great importance. The present study compares in vivo patellofemoral kinematic parameters and the contact mechanism of volunteers with healthy knees and patients with low flexion patellofemoral instability (PFI). The study was performed with a high-resolution dynamic MRI.

MATERIAL/METHODS

In a prospective cohort study, the patellar shift, patella rotation and the patellofemoral cartilage contact areas (CCA) of 17 patients with low flexion PFI were analyzed and compared with 17 healthy volunteers, matched via the TEA distance and sex, in unloaded and loaded conditions. MRI scans were carried out for 0°, 15° and 30° knee flexion in a custom-designed knee loading device. To suppress motion artifacts, motion correction was performed using a moiré phase tracking system with a tracking marker attached to the patella. The patellofemoral kinematic parameters and the CCA was calculated on the basis of semi-automated cartilage and bone segmentation and registrations.

RESULTS

Patients with low flexion PFI showed a significant reduction in patellofemoral CCA for 0° (unloaded: p = 0.002, loaded: p = 0.004), 15° (unloaded: p = 0.014, loaded: p = 0.001) and 30° (unloaded: p = 0.008; loaded: p = 0.001) flexion compared to healthy subjects. Additionally, patients with PFI revealed a significantly increased patellar shift when compared to volunteers with healthy knees at 0° (unloaded: p = 0.033; loaded: p = 0.031), 15° (unloaded: p = 0.025; loaded: p = 0.014) and 30° flexion (unloaded: p = 0.030; loaded: p = 0.034) There were no significant differences for patella rotation between patients with PFI and the volunteers, except when, under load at 0° flexion, PFI patients showed increased patellar rotation (p = 0.005. The influence of quadriceps activation on the patellofemoral CCA is reduced in patients with low flexion PFI.

CONCLUSION

Patients with PFI showed different patellofemoral kinematics at low flexion angles in both unloaded and loaded conditions compared to volunteers with healthy knees. Increased patellar shifts and decreased patellofemoral CCAs were observed in low flexion angles. The influence of the quadriceps muscle is diminished in patients with low flexion PFI. Therefore, the goal of patellofemoral stabilizing therapy should be to restore a physiologic contact mechanism and improve patellofemoral congruity for low flexion angles.

Improving Technical Outcome in Osteochondral Allograft Transplantation of the Femoral Trochlea: The Role of Contoured Guides, Experience Level, Graft Size, and Graft Position

Background

The use of coring instrumentation for osteochondral allograft (OCA) transplantation of the femoral trochlea is challenging due to the complex topography of this anatomical area.

Purpose

We sought to determine the effect of flat guides versus guides contoured to the surface of the trochlea on graft step-off in trochlear OCAs performed on a foam bone model. We also determined the effect of surgeon experience level and graft size on step-off.

Study Design

Controlled laboratory study.

Methods

Allograft harvesters were produced in 3 different sequential sizes with either a flat or a contoured undersurface. The guides matched one another in all aspects of shape and size except for the undersurface contour. The contoured undersurface generally matched the surface of the bone model trochlea but was not customized to that surface. A total of 72 foam femora were obtained. Identical trochlear stellate lesions of 3 different sizes (small, medium, and large) were created using 3-dimensional printed surface templates. A total of 6 surgeons (3 attending and 3 resident surgeons) performed OCAs of each trochlear lesion. Each surgeon performed 1 graft for each size and each guide type (n = 6 per surgeon). A specialized digital caliper was prepared that allowed the measurement of graft step-off to within 0.01 mm at a distance of 5 mm between the 2 sensors. The measurements were performed at 8 positions around the clockface of the grafts.

Results

Grafts performed with the contoured guides had a mean step-off of 0.43 ± 0.37 mm. Grafts performed with the flat guides had a mean step-off of 0.74 ± 0.78 mm (P < .0001). Experience level did not have a significant effect on graft step-off (P = .81). There was no identifiable pattern indicating higher step-off at any one position on the clockface.

Conclusion

In this study, contoured grafts had significantly lower step-offs compared with flat guides. Experience level, clockface position, and graft size did not affect step-off.

Patellar Component Design Does Not Impact Clinical Outcomes in Primary Total Knee Arthroplasty

BACKGROUND

Round or oval implants are used in patellar resurfacing during total knee arthroplasty (TKA). However, whether component geometry affects clinical outcomes is unclear. This study aimed to determine if one implant shape conferred superior outcomes to the other.

METHODS

A retrospective review of primary TKA cases performed from 2016 to 2020 was conducted at an urban, tertiary academic center. Four hundred consecutive, primary TKAs were included in these analyses. Cases were included if a surgeon used the round design then oval design for fifty consecutive cases. Baseline demographic data and radiographic measurements were assessed. Surgical data, reasons for revision, and patient-reported outcome measures were analyzed. Independent samples t-test and chi-square tests were used to compare means and proportions. There were no demographic differences between the cohorts.

RESULTS

Postoperative patellar tilt was statistically different between the cohorts. Sixteen patients required revision surgery; however, revision rates did not differ between the cohorts. Of the 9 rounds, 1 button was revised for infection. Of the 7 ovals, 1 button was revised for infection and 1 for loosening. Veterans RAND 12 Physical Component Score at 3 months postoperatively was higher for the round cohort, but no differences were observed at 1 year.

CONCLUSION

While radiographic patellar tilt was significantly different between the cohorts, there was no clinical correlation in outcomes at 3 months or 1 year postoperatively. Longer-term follow-up studies are needed to evaluate the implications of patellar component design on outcomes and function. Nevertheless, the current study affirms that both designs are clinically equivalent which should be used to guide clinical decision-making.

LEVEL III EVIDENCE

Retrospective Cohort.

Anteromedialization Tibial Tubercle Osteotomy Improves Patellar Contact Forces: A Cadaveric Model of Patellofemoral Dysplasia

BACKGROUND

Patellofemoral (PF) dysplasia is common in patients with recurrent patellar instability. Tibial tubercle osteotomy (TTO) is performed with goals of correcting patellar maltracking and redistributing contact forces across the PF joint. The biomechanical effects of TTO in the setting of PF dysplasia have not been quantified.

PURPOSE/HYPOTHESIS

To quantify patellar contact mechanics and kinematics after TTO in the setting of PF dysplasia. We hypothesized that a simulated anteromedialization (AMZ) TTO would improve PF contact mechanics as compared with a pure medialization TTO.

STUDY DESIGN

Controlled laboratory study.

METHODS

PF dysplasia with Dejour type D classification was simulated in 7 cadaveric knees by replacing the native patellar and trochlear surfaces with synthetic polymeric patellar and trochlear implants. On each specimen, a flat TTO was fixed in 3 distinct positions simulating a pathologic lateralized tubercle (pathologic condition), a medialized tubercle (Elmslie Trillat), and an AMZ tubercle. The sum of forces acting on the medial and lateral patellar facet and patellar kinematics was computed for each knee for each condition from 0° to 70° of flexion at 10° increments.

RESULTS

Relative to the pathologic condition, AMZ TTO decreased contact forces across the lateral facet (20°-50° and 70° of flexion). Relative to the pathologic condition, Elmslie Trillat TTO had no effect on contact forces on either compartment. Relative to the Elmslie Trillat TTO, the AMZ TTO had significantly decreased contact forces across the medial facet (at 40°, 60°, and 70° of flexion). No significant differences in joint kinematics occurred across any groups.

CONCLUSION

Of all groups studied, AMZ TTO resulted in significantly decreased patellar contact forces in simulated dysplastic PF joints. AMZ may be considered in certain patients with PF dysplasia to avoid medial compartment PF chondral overload.

CLINICAL RELEVANCE

PF dysplasia is common in patients with recurrent patellar instability who warrant surgical intervention to prevent subsequent recurrence. Numerous interventions to treat this condition, including various TTOs, have been proposed without a clear consensus. This cadaveric biomechanical study demonstrates that AMZ TTO resulted in more favorable PF contact mechanics than Elmslie Trillat TTO in a model representing PF dysplasia. AMZ TTO may be considered for patients in the setting of recurrent instability with PF dysplasia to avoid cartilage overload on the medial compartment of the PF joint.

Lateral Patellofemoral Ligament Reconstruction: A Biomechanical Comparison of 2 Techniques

BACKGROUND

The importance of maintaining lateral patellar stabilizing structures has been demonstrated by the presence of iatrogenic medial patellar instability after lateral retinacular release (LRR) procedures. In patients with medial patellar instability, lateral patellofemoral ligament (LPFL) reconstruction has been clinically shown to restore patellar stability while improving patient-reported outcomes. However, the biomechanics associated with different LPFL reconstruction techniques remain largely unknown.

PURPOSE

To (1) investigate whether LPFL reconstruction restores medial patellar translation compared with the intact state after LRR and (2) evaluate for any biomechanical differences between soft tissue and osseous LPFL reconstruction techniques.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 7 knees were included in the final analysis. The knees were dissected, and the tibia and femur were potted. An eye screw was then placed at the midpoint of the patella perpendicular to the medial surface. A custom jig was constructed to allow for a 1-kg load to be applied to the quadriceps muscle. Medial patellar displacement was investigated at 0°, 10°, 20°, 30°, 45°, 60°, and 90° of knee flexion using a tensile testing machine with a 20-N medial force applied to the patella. Medial patellar displacement was assessed in 4 states: intact, LRR, soft tissue LPFL reconstruction (inserted through incisions in the iliotibial band, quadriceps tendon, and patellar tendon), and osseous LPFL reconstruction.

RESULTS

The LRR group had significantly greater medial patellar translation compared with the intact group throughout flexion (P < .01 to P = .029). The soft tissue LPFL reconstruction group demonstrated significantly greater medial patellar translation at 30° (P = .020) and 45° (P = .025) compared with the intact group, with less translation compared with the LRR group at all degrees of knee flexion except for 45° (P = .065). The osseous LPFL reconstruction group demonstrated significantly greater medial patellar translation compared with the intact group at 30° of flexion (P = .036), with significantly less translation compared with the LRR group from 0° to 30° (P < .01 to P = .013). The soft tissue LPFL reconstruction group (15.94 ± 2.55 mm) demonstrated significantly greater medial patellar translation at 10° of flexion compared with the osseous LPFL reconstruction group (14.16 ± 2.34 mm) (P = .033).

CONCLUSION

Soft tissue LPFL reconstruction led to significantly greater medial patellar translation at 30° and 45° compared with the intact state, while osseous LPFL reconstruction produced significantly greater translation only at 30°. Both the soft tissue and the osseous reconstruction techniques resulted in comparable medial patellar translation at all degrees of knee flexion except for 10°, in which osseous reconstruction was more similar to the intact state.

CLINICAL RELEVANCE

Compared with LRR, soft tissue LPFL reconstruction was able to restore stability against medial patellar translation at most degrees of knee flexion, while osseous LPFL reconstruction did not provide adequate stabilization beyond 30° of flexion. While the LPFL does appear to have osseous insertions, soft tissue reconstruction functioned more similarly to the intact state after LRR.

Anatomic Factors Associated With Osteochondral Allograft Matching for Trochlear Cartilage Defects: A Computer-Simulation Study

BACKGROUND

Articular step-off between the donor and recipient in osteochondral allograft transplant has been shown to alter contact pressures. Currently, commercial allograft donor selection is primarily based on simple anatomic parameters such as trochlear length, trochlear width, and tibial width.

PURPOSE

To identify anatomic factors associated with optimal graft matching by using a 3-dimensional simulation model.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Computed tomography images of 10 cadaveric trochlear specimens were obtained to generate 3-dimensional models. Circular defects were created virtually in the recipient trochleae at both superolateral (18.0 mm and 22.5 mm) and central (18.0 mm, 22.5 mm, 30.0 mm) locations. The donor models were virtually projected onto the defect models, and the most optimal graft from any location of the donor specimen was selected. Cartilage incongruity, subchondral bone incongruity, and peripheral articular step-off were calculated for each graft-defect combination. Linear regression models were generated to identify predictors of incongruity, step-off, and the effect of sulcus and sagittal angle mismatch. Akaike information criterion-driven stepwise regression models were generated to identify multivariate predictors.

RESULTS

Ideal matches were found for 100% of superolateral defects but for only 15% to 53% of central defects, depending on the defect size. Multivariate stepwise regression identified laterality (odds ratio [OR], 0.54; P = .081), sulcus angle (OR, 0.79; P < .001), sagittal angle (OR, 0.83; P = .001), lateral radius of curvature (OR, 0.81; P < .001), and medial facet width (OR, 0.86; P = .155) as predictors of ideal graft matching. In central defects with proud grafts, increasing sagittal angle and sulcus angle resulted in significantly (P < .001) increased articular step-off, which became sequentially larger with defect size.

CONCLUSION

Sagittal angle, sulcus angle, and lateral radius of curvature mismatch should be used to determine optimal donor allografts, especially in the setting of large (30-mm) central defects. Increasing sulcus angle and sagittal angle mismatch correlated with increasing step-off in proud grafts, whereas sulcus angle and sagittal angle inconsistently correlated with step-off in recessed grafts.

CLINICAL RELEVANCE

Additional descriptive trochlear measurements should be incorporated into the algorithm for donor selection. These findings can be used to identify acceptable mismatch parameters.

YouTube provides insufficient information on patellofemoral instability

OBJECTIVE

Videos uploaded to YouTube do not go through a review process, and therefore, videos related to patellofemoral instability may have little educational value. The purpose of this study was to assess the educational quality of YouTube videos regarding patellofemoral instability.

METHODS

A standard search was performed on the YouTube database using the following terms: "unstable kneecap," "patellar instability," "patellofemoral instability," "kneecap dislocation," and "patellar dislocation," and the top 50 videos based on the "relevance" assignment of the YouTube algorithm were included for analysis. The properties, content, and source of each video were recorded. The educational quality of videos was analyzed according to scores obtained using DISCERN, the criteria of Journal of the American Medical Association, Global Quality Score, and Patellofemoral Instability Specific Score, and the quality of the videos was evaluated according to the groupings of these scoring systems.

RESULTS

A total of 250 videos were identified, of which 89 were included in the study for analysis. The mean video duration was 11.72 ± 22.03 minutes. The median number of views was 4516.5 (range, 3-6 044 971). The content of the videos was disease-specific in 60%, 20% were related to surgical technique or approach, and 14.1% were exercise videos. Most of the videos were uploaded by physicians (33.7%). The Global Quality Score and DISCERN scores were significantly correlated with video duration. The Patellofemoral Instability Specific Score was significantly correlated with video duration, number of views, view rate, likes, and Video Power Index. According to the DISCERN classification, 69.9% of the videos were very insufficient or insufficient. According to the Patellofemoral Instability Specific Score, 65.2% of videos were evaluated as very low or low. According to the Global Quality Score, 60.7% of videos were rated as poor quality.

CONCLUSION

The quality of YouTube videos about Patellofemoral instability is insufficient. It was found that viewers tend to watch short and low-quality videos.

Articular contact motion at the knee during daily activities

We combined mobile biplane X-ray imaging and magnetic resonance imaging to measure the regions of articular cartilage contact and cartilage thickness at the tibiofemoral and patellofemoral joints during six functional activities: standing, level walking, downhill walking, stair ascent, stair descent, and open-chain (non-weight-bearing) knee flexion. The contact centers traced similar paths on the medial and lateral femoral condyles, femoral trochlea, and patellar facet in all activities while their locations on the tibial plateau were more varied. The translations of the contact centers on the femur and patella were tightly coupled to the tibiofemoral flexion angle in all activities (r²  > 0.95) whereas those on the tibia were only moderately related to the flexion angle (r²  > 0.62). The regions of contacting cartilage were significantly thicker than the regions of non-contacting cartilage on the patella, femoral trochlea, and the medial and lateral tibial plateaus in all activities (p < 0.001). There were no significant differences in thickness between contacting and non-contacting cartilage on the medial and lateral femoral condyles in all activities, except open-chain knee flexion. Our results provide partial support for the proposition that cartilage thickness is adapted to joint load and do not exclude the possibility that other factors, such as joint congruence, also play a role in regulating the structure and organization of healthy cartilage. The data obtained in this study may serve as a guide when evaluating articular contact motion in osteoarthritic and reconstructed knees.

Factors Associated With Pain and Function Before Medial Patellofemoral Ligament Reconstruction

Background:

Medial patellofemoral ligament (MPFL) reconstruction is performed to treat recurrent patellar instability. Measurement of joint pain and function at the time of surgery has been demonstrated to be a predictor of the final outcomes in many surgical procedures.

Purpose/Hypothesis:

The purpose of this study was to evaluate the relationship between baseline patient characteristics, mental health, and intraoperative findings and patient-reported knee pain and function at the time of MPFL reconstruction. We hypothesized that patient characteristics and associated pathology would be associated with the degree of pain and dysfunction.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Included were skeletally mature patients who underwent unilateral open MPFL reconstruction between 2015 and 2020 at a single institution. Baseline descriptive information was collected, and the following outcome measures were administered preoperatively: the Veterans RAND 12-Item Health Survey Mental Component Score (VR-12 MCS) and the Knee injury and Osteoarthritis Outcome Score (KOOS) Pain, Physical Function Short Form (PS), and Quality of Life (QoL) subscales. Intraoperative findings were collected in a standardized format. Patient characteristics, preoperative variables, intraoperative findings, and VR-12 MCS were used as risk factors, and multivariate analysis was conducted to assess for relationships with the KOOS subscale scores.

Results:

In total, 201 patients with patella dislocations were included in this analysis. Intraoperatively, 122 patients (60.7%) had either normal cartilage or grade 1 or 2 cartilage injury, 79 patients (39.3%) had grade 3 or 4 cartilage injury, 35 patients (17.4%) had a loose body, and 3 patients (1.49%) had evidence of synovitis. Younger age (P = .012), male sex (P < .001), never having smoked (P = .029), and lower baseline VR-MCS (P < .001) were significantly associated with higher baseline KOOS Pain scores. Older age (P = .035), female sex (P = .003), higher body mass index (P = .005), and lower baseline VR-12 MCS (P < .001) were significantly associated with higher baseline KOOS PS scores. Younger age (P = .003), male sex (P < .001), lower baseline VR-12 MCS (P < .001), and no dysplasia (P = .023) were significantly associated with higher baseline KOOS QoL scores.

Conclusion:

Patient age, sex, and baseline VR-12 MCS were associated with all 3 baseline KOOS subscale scores, whereas intraoperative findings outside of trochlear dysplasia were not associated with any of the KOOS subscale scores.

Cemented Patellar Implant Malposition: A Non-Issue for the Painful Total Knee Arthroplasty

BACKGROUND

Non-optimal patellofemoral relationships may influence treatment decisions during revision total knee arthroplasty (TKA). We performed this study to determine whether patellar implant malposition or patellar tilt is associated with inferior patient-reported outcome scores or patient satisfaction after primary TKA.

METHODS

We identified 396 TKA patients (439 knees) from an institutional registry who had undergone patellar resurfacing, with preoperative and 6-week postoperative radiographs available, and patient-reported outcome measures (PROMs) completed at least 1 year after surgery (mean 505 days). Preoperative patient demographic characteristics, patient-reported expectations, National Institutes of Health - Patient Reported Outcomes Measurements Instrument Systems global health, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, and University of California Los Angeles activity scores were compared between 60 TKAs performed with non-optimal patellofemoral relationships (36 patellar implant malposition, 24 patellar tilt) and 379 TKAs performed with optimal patellar implant placement.

RESULTS

There were no differences between the 2 cohorts regarding demographic features, preoperative radiographic disease severity, expectations, and PROMs; or postoperative tibiofemoral component alignment, PROMs, and patient-reported satisfaction (P = .48). Knee Injury and Osteoarthritis Outcome Score for Joint Replacement improved similarly (P = .62) for patients with optimal resurfacing (48.5-77.6 points) and non-optimal resurfacing (47.7-76.6 points). A similar proportion of optimal and suboptimal resurfaced patients reported being satisfied with their TKA (92.7% vs 88.1%, P = .29).

CONCLUSION

Although suboptimal patellofemoral relationships may prompt treatment considerations during revision TKA, the data obtained from this study do not suggest that patellar implant malposition or patellar tilt independently contribute to postoperative pain, functional limitation, or dissatisfaction.

LEVEL OF EVIDENCE

This is a level III, retrospective cohort study.

Utility of Diagnostic Ultrasound in the Assessment of Patellar Instability

Background

The use of imaging to diagnose patellofemoral instability is often limited by the inability to dynamically load the joint during assessment. Therefore, the diagnosis is typically based on physical examination using the glide test to assess and quantify lateral patellar translation. However, precise quantification with this technique remains difficult.

Purpose

To quantify patellar position using ultrasound imaging under dynamic loading conditions to distinguish between knees with and without medial patellofemoral complex (MPFC) injury.

Study Design

Controlled laboratory study.

Methods

In 10 cadaveric knees, the medial patellofemoral distance was measured to quantify patellar position from 0° to 40° of knee flexion at 10° increments. Knees were evaluated at each flexion angle under unloaded conditions and with 20 N of laterally directed force on the patella to mimic the glide test. Patellar position measurements were made on ultrasound images obtained before and after MPFC transection and compared for significant differences. To determine the ability of medial patellofemoral measurements to differentiate between MPFC-intact and MPFC-deficient states, area under the receiver operating characteristic (ROC) curve analysis and the Delong test were used. The optimal cutoff value to distinguish between the deficient and intact states was determined using the Youden J statistic.

Results

A significant increase in medial patellofemoral distance was observed in the MPFC-deficient state as compared with the intact state at all flexion angles (P = .005 to P < .001). When compared with the intact state, MPFC deficiency increased medial patellofemoral distance by 32.8% (6 mm) at 20° of knee flexion under 20-N load. Based on ROC analysis and the J statistic, the optimal threshold for identifying MPFC injury was 19.2 mm of medial patellofemoral distance at 20° of flexion under dynamic loading conditions (area under the ROC curve = 0.93, sensitivity = 77.8%, specificity = 100%, accuracy = 88.9%).

Conclusion

Using dynamic ultrasound assessment, we found that medial patellofemoral distance significantly increases with disruption of the MPFC.

Clinical Relevance

Dynamic ultrasound measurements can be used to accurately detect the presence of complete MPFC injury.

Dynamic Mediolateral Patellar Translation Is a Sex- and Size-Independent Parameter of Adult Proximal Patellar Tracking Using Dynamic 3 Tesla Magnetic Resonance Imaging

PURPOSE

To provide normal values for physiological patellofemoral tracking in a representative group of healthy individuals, as well as sex differences, using real-time 3T-magnetic resonance imaging (MRI) and to test for the reliability of the presented technique.

METHODS

One hundred knees of healthy individuals with no history of patellofemoral symptoms were scanned with dynamic MRI sequences, during repetitive cycles of flexion (40°) and full extension. Within a 30-seconds time-frame, three simultaneous, transverse slices were acquired. Dynamic mediolateral patellar translation (dMPT) and dynamic patellar tilt (dPT) were measured on two occasions by two independent examiners. Common radiological parameters were measured using static MRI, and correlations were calculated.

RESULTS

100 knees (53 right, 47 left; age: 26.7 ± 4.4 years; BMI: 22.5 ± 3.1) of 57 individuals (27 females, 30 males) were included. Mean height was 170.1 ± 7.7 cm in women and 181.8 ± 6.4 cm in men. Average patella diameter was 37.9 ± 2.7 (95% CI 37.1-38.7) mm in women and 42.4 ± 3.2 (95% CI 41.5-43.3) mm in men. In females, the patellar diameters and intercondylar distances were significantly smaller than in males (P < .001). Radiological parameters for patellar maltracking were within the normal range. During the range of motion, mean dMPT was 1.7 ± 2.4 (95% CI .9-2.5) mm in females and 1.8 ± 2.7 (95% CI 1.1-2.6) mm in males (P = .766). Mean dPT was 1.3 ± 2.9° (95% CI .4-2.1°) in females and -0.2 ± 3.8° (95% CI -1.2-.9°) in males (P = .036). Neither dMPT nor dPT was correlated with height, BMI, or patellar diameter. Intercondylar distance correlated weakly with dPT (r = -.241; P = .041). Intra- and interrater reliability were excellent for dMPT and dPT.

CONCLUSION

Dynamic mediolateral patellar translation is a size- and sex-independent parameter for proximal patellar tracking. In healthy individuals without patellofemoral abnormalities normal dMPT proximal to the trochlea groove was 1.7 ± 2.5 (1.2-2.2) mm, independent of size or sex. Normal dPT showed a dependency on sex and was 1.3 ± 2.9 (.4-2.1)° in women and -0.2 ± 3.8 (-1.2-0.9)° in men.

LEVEL OF EVIDENCE

Level II, diagnostic study.

Variation in the patellar tendon moment arm identified with an improved measurement framework

The mechanical advantage of the knee extensor mechanism depends heavily on the patellar tendon moment arm (PTMA). Understanding which factors contribute to its variation may help improve functional outcomes following arthroplasty. This study optimized PTMA measurement, allowing us to quantify the contribution of different variables. The PTMA was calculated about the instantaneous helical axis of tibiofemoral rotation from optical tracked kinematics. A fabricated knee model facilitated calculation optimization, comparing four data smoothing techniques (raw, Butterworth filtering, generalized cross-validated cubic spline-interpolation and combined filtering/interpolation). The PTMA was then measured for 24 fresh-frozen cadaveric knees, under physiologically based loading and extension rates. Combined filtering/interpolation enabled sub-mm PTMA calculation accuracy throughout the range of motion (root-mean-squared error 0.2 mm, max error 0.4 mm), whereas large errors were measured for raw, filtered-only and interpolated-only techniques at terminal flexion/extension. Before scaling, the mean PTMA was 46 mm; PTMA magnitude was consistently larger in males (mean differences: 5 to 10 mm, p < .05) and was strongly related to knee size: larger knees have a larger PTMA. However, while scaling eliminated sex differences in PTMA magnitude, the peak PTMA occurred closer to terminal extension in females (female 15°, male 29°, p = .01). Knee size accounted for two-thirds of the variation in PTMA magnitude, but not the flexion angle where peak PTMA occurred. This substantial variation in angle of peak PTMA has implications for the design of musculoskeletal models and morphotype-specific arthroplasty. The developed calculation framework is applicable both in vivo and vitro for accurate PTMA measurement.

Inconsistencies in Reporting Risk Factors for Medial Patellofemoral Ligament Reconstruction Failure: A Systematic Review

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction is a common surgical treatment for patients with recurrent patellar instability. A variety of risk factors, such as age, trochlear dysplasia, patella alta, and increased tibial tubercle-trochlear groove (TT-TG) distance, have been identified and may lead to postoperative failure or poor outcomes.

PURPOSE

While a large number of risk factors have been identified, significant heterogeneity exists in evaluating and reporting these risk factors in the literature. The goal of this study was to perform a systematic review to determine risk factors associated with worse outcomes after MPFL reconstruction and their consistency of being controlled for or analyzed among studies.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic review of the literature was performed using the MEDLINE database to identify relevant clinical outcome studies after MPFL reconstruction for recurrent patellar instability. Eligible studies were evaluated for risk factors that were associated with MPFL failure, defined as recurrent instability or lack of improvement on patient-reported outcome (PRO) scores. Each study was then evaluated for inclusion of these risk factors.

RESULTS

Ten studies were included in the final analysis, comprising 1287 knees from 1275 patients who underwent isolated MPFL reconstruction. Of these 10 studies, 8 defined outcomes based on PROs and 3 defined outcomes based on postoperative recurrent instability (1 study included both outcomes). In the PRO failure group, 12 risk factors were found across all studies: trochlear dysplasia, trochlear bump height, elevated TT-TG, patellar tilt, hyperlaxity, age at first dislocation, age at surgery, body mass index, bilateral symptoms, WARPS/STAID score (weak atraumatic, risky anatomy, pain, and subluxation/strong, traumatic, anatomy normal, instability, and dislocation), femoral tunnel malposition, and femoral tunnel widening. In the recurrent instability failure group, 7 risk factors were found across all studies: trochlear dysplasia, bump height, patella alta, higher sulcus angle, higher congruence angle, preoperative J sign, and femoral tunnel malposition. Trochlear dysplasia and femoral tunnel malposition were consistently cited in several studies as risk factors for worse PROs and higher rates of recurrent instability. Patella alta was indicated as a significant risk factor for recurrent instability in 1 of 2 studies analyzing postoperative instability failures and was not associated with worse PROs in any of the studies analyzed. Similarly, elevated TT-TG distance was not a significant risk factor in any of the studies that analyzed recurrent instability as the failure endpoint.

CONCLUSION

While various risk factors are postulated to affect outcomes after MPFL reconstruction, there remains inconsistency within the literature regarding the inclusion of all risk factors in a given analysis. Furthermore, the significance of these risk factors varies among studies in terms of whether they affect postoperative outcomes. We found that more severe trochlear dysplasia (types C and D) and femoral tunnel malposition (>10 mm from Schöttle's point) appear to have the most consistent effect on producing higher rates of recurrent dislocation as well as worse PROs. Despite this, the role of concomitant bony procedures to adjust certain pathoanatomic risk factors in addition to MPFL reconstruction remains unknown. Future high-level studies must be conducted that respect the multifactorial nature of patellar instability and should analyze all risk factors (demographic, anatomic, and radiographic) reported to affect outcomes.

A Comprehensive Description of the Lateral Patellofemoral Complex: Anatomy and Anisometry

BACKGROUND

The lateral patellofemoral complex (LPFC) is an important stabilizer of the patella composed of the lateral retinacular structures including the lateral patellofemoral ligament (LPFL), the lateral patellomeniscal ligament (LPML), and the lateral patellotibial ligament (LPTL). While the isolated anatomy of the LPFL has been previously described, no previous study has investigated the entirety of the LPFC structure, length changes, and radiographic landmarks. An understanding of LPFC anatomy is important in the setting of LPFL injury or previous lateral release resulting in iatrogenic medial instability requiring LPFC reconstruction.

PURPOSE

To both qualitatively and quantitatively describe the anatomy and length changes of the LPFC on gross anatomic dissections and standard radiographic views.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired cadaveric specimens were utilized in this study. Specimens were dissected to identify distinct attachments of the LPFL, LPML, and LPTL. Ligament lengths, footprints, and centers of each attachment were described with respect to osseous landmarks using a 3-dimensional coordinate measuring device. Ligament length changes were also assessed from 0° to 90° of flexion. Radiopaque markers were subsequently utilized to describe attachments on standard anteroposterior and lateral radiographic views.

RESULTS

The individual elements of the LPFC were identified in all specimens. The LPFL patellar attachment had an average total length of 22.5 mm (range, 18.3-27.5 mm), involving a mean of 59% (range, 50%-75%) of the sagittal patella. Based on the average patellar size, a mean of 63% of the LPFL attached to the patella, and the remainder (11.1 ± 1.4 mm) inserted into the patellar tendon. The femoral attachment of the LPFL had a mean maximum length of 24.4 ± 4.3 mm. The center of the LPFL femoral attachment was a mean distance of 13.5 ± 3.2 mm anterior and distal to the lateral epicondyle. The LPFL demonstrated significant shortening, especially in the first 45° of flexion (7.5 ± 5.1 mm). In contrast, the LPTL (5.5 ± 3.0 mm) and LPML (10.0 ± 3.3 mm) demonstrated significant shortening from 45° to 90°. On lateral radiographs, the center of the femoral attachment of the LPFL was a mean total distance of 19.2 ± 7.2 mm from the lateral epicondyle.

CONCLUSION

The most important findings of this study were the correlative anatomy of 3 distinct lateral patellar ligaments (LPFL, LPML, and LPTL) and their anisometry through flexion. All 3 components demonstrated significant shortening during flexion. The quantitative and radiographic measurements detailed the LPFL osseous attachment on the patella; soft tissue attachment on the patellar tendon; and finally, the osseous insertion on the femur distal and anterior to the lateral epicondyle. Similarly, the authors documented the meniscal insertion of the LPML and defined a patellar insertion of the LPTL and LPML as a single attachment. These data allow for reproducible landmarks to aid in the understanding and reconstruction of the lateral patellar restraints.

CLINICAL RELEVANCE

The data produced from this investigation provide a comprehensive description of these 3 lateral patellar stabilizers (LPFL, LPML, LPTL). These data can be used intraoperatively to facilitate anatomic reconstructions of the lateral patellar stabilizers.

Relationship of Patellofemoral Osteoarthritis to Changes in Performance-based Physical Function Over 7 Years: The Multicenter Osteoarthritis Study

OBJECTIVE

To determine the relationship of patellofemoral osteoarthritis (PFOA) to changes in performance-based function over 7 years.

METHODS

There were 2666 participants (62.2 ± 8.0 yrs, BMI 30.6 ± 5.9 kg/m2, 60% female) from the Multicenter Osteoarthritis Study with knee radiographs at baseline who completed repeated chair stands and a 20-meter walk test (20MWT) at baseline, 2.5, 5, and 7 years. Generalized linear models assessed the relation of radiographic PFOA and radiographic PFOA with frequent knee pain to longitudinal changes in performance-based function. Analyses were adjusted for age, sex, BMI, tibiofemoral OA, and injury/surgery.

RESULTS

Linear models demonstrated a significant group-by-time interaction for the repeated chair stands (P = 0.04) and the 20MWT (P < 0.0001). Those with radiographic PFOA took 1.01 seconds longer on the repeated chair stands (P = 0.02) and 1.69 seconds longer on the 20MWT (P < 0.0001) at 7 years compared with baseline. When examining the relation of radiographic PFOA with frequent knee pain to performance-based function, there was a significant group-by-time interaction for repeated chair stands (P = 0.05) and the 20MWT (P < 0.0001). Those with radiographic PFOA with frequent knee pain increased their time on the repeated chair stands by 1.12 seconds (P = 0.04) and on the 20MWT by 1.91 seconds (P < 0.0001) over 7 years.

CONCLUSION

Individuals with radiographic PFOA and those with radiographic PFOA with frequent knee pain have worsening of performance-based function over time. This knowledge may present opportunities to plan for early treatment strategies for PFOA to limit functional decline over time.

Infrapatellar fat pad volume and Hoffa-synovitis after ACL reconstruction: Association with early osteoarthritis features and pain over 5 years

Infrapatellar fat pad (IPFP) morphology and Hoffa-synovitis may be relevant to the development and progression of post-traumatic osteoarthritis (OA). We aimed to compare IPFP volume and Hoffa-synovitis in participants with anterior cruciate ligament reconstruction (ACLR) and uninjured controls, and to determine their association with prevalent and worsening early knee OA features and pain in participants post-ACLR. We assessed IPFP volume and Hoffa-synovitis from magnetic resonance imaging (MRI) in 111 participants 1-year post-ACLR and 20 uninjured controls. Patellofemoral and tibiofemoral cartilage and bone marrow lesions (BMLs) were assessed from MRIs at 1 and 5 years post-ACLR, and worsening defined as any longitudinal increase in lesion size/severity. IPFP volume and Hoffa-synovitis prevalence were compared between groups with analysis of covariance and χ ² tests, respectively. Generalized linear models assessed the relation of IPFP volume and Hoffa-synovitis to prevalent and worsening features of OA and knee pain (Knee injury and Osteoarthritis Outcome Score-Pain Subscale, Anterior Knee Pain Scale). No significant between-group differences were observed in IPFP volume (ACLR 34.39 ± 7.29cm³ , Control 34.27 ± 7.56cm³ ) and Hoffa-synovitis (ACLR 61%, Control 80%). Greater IPFP volume at 1-year post-ACLR was associated with greater odds of patellofemoral BMLs at 1-year (odds ratio [OR] [95% confidence intervals]: 1.104 [1.016, 1.200]) and worsening tibiofemoral cartilage lesions at 5-year post-ACLR (OR: 1.234 [1.026, 1.483]). Hoffa-synovitis at 1-year post-ACLR was associated with greater odds of worsening patellofemoral BMLs at 5-year post-ACLR (OR: 7.465 [1.291, 43.169]). In conclusion, IPFP volume and Hoffa-synovitis prevalence are similar between individuals 1-year post-ACLR and controls. Greater IPFP volume and Hoffa-synovitis appear to be associated with the presence and worsening of some early OA features in those post-ACLR, but not pain.

Cartilage Restoration of Patellofemoral Lesions: A Systematic Review

PURPOSE

This study aimed to systematically analyze the postoperative clinical, functional, and imaging outcomes, complications, reoperations, and failures following patellofemoral cartilage restoration surgery.

METHODS

This review was conducted according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). PubMed, EMBASE, and Cochrane Library databases were searched up to August 31, 2018, to identify clinical studies that assessed surgical outcomes of patellofemoral cartilage restoration surgery. The Methodological Index for Non-Randomized Studies (MINORS) was used to assess study quality.

RESULTS

Forty-two studies were included comprising 1,311 knees (mean age of 33.7 years and 56% males) and 1,309 patellofemoral defects (891 patella, 254 trochlear, 95 bipolar, and 69 multiple defects, including the patella or trochlea) at a mean follow-up of 59.2 months. Restoration techniques included autologous chondrocyte implantation (56%), particulated juvenile allograft cartilage (12%), autologous matrix-induced chondrogenesis (9%), osteochondral autologous transplantation (9%), and osteochondral allograft transplantation (7%). Significant improvement in at least one score was present in almost all studies and these surpassed the minimal clinically important difference threshold. There was a weighted 19%, 35%, and 6% rate of reported complications, reoperations, and failures, respectively. Concomitant patellofemoral surgery (51% of patients) mostly did not lead to statistically different postoperative outcomes.

CONCLUSION

Numerous patellofemoral restoration techniques result in significant functional improvement with a low rate of failure. No definitive conclusions could be made to determine the best surgical technique since comparative studies on this topic are rare, and treatment choice should be made according to specific patient and defect characteristics.

LEVEL OF EVIDENCE

Level IV, systematic review of level II to IV studies.

Internal Fixation of Lateral Trochlear Groove Osteochondritis Dissecans With Simultaneous Lateral Retinacular Lengthening in Adolescent Athletes

BACKGROUND

The goals of operative treatment for the adolescent athlete with unstable osteochondritis dissecans (OCD) lesion are rigid fixation and prevention of recurrence.

PURPOSE

To evaluate clinical and radiological outcomes of internal fixation of lateral trochlear groove OCD with simultaneous lateral retinacular lengthening.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Adolescent athletes who had undergone internal fixation and simultaneous lateral retinacular lengthening for an unstable OCD lesion of the lateral trochlear groove were retrospectively reviewed. Subjective assessments included the Lysholm score, International Knee Documentation Committee (IKDC) subjective score, Tegner activity scale, and an athletic questionnaire. Functional tests included isokinetic muscle strength, single-leg hop for distance, single-leg vertical jump, and Y-balance. Pre- and postoperative radiographs and magnetic resonance images were reviewed.

RESULTS

The mean ± SD age of the 17 patients included in this study was 15.9 ± 0.9 years; last clinical follow-up duration was 37.7 ± 8.1 months. At the last follow-up, the Lysholm score improved from 68.7 ± 15.3 to 93.4 ± 12.4 and the IKDC subjective score from 60.2 ± 14.7 to 88.7 ± 12.7 (P < .001). The mean Tegner activity scale score was 9.4 ± 0.5 before injury and 8.9 ± 1.2 at the last follow-up (P = .059). The limb symmetry indices of isokinetic muscle strength, single-leg hop for distance, single-leg vertical jump, and Y-balance improved at the last follow-up; the mean limb symmetry index was ≥85% in each functional test. Regarding the athletic questionnaire, 16 (94.1%) patients were satisfied with the surgery. At the last follow-up, 2 patients had higher ability after returning to sports, 11 had the same ability, and 3 had lower ability than the preinjury level. Postoperative magnetic resonance imaging at 12-month follow-up showed that the OCD lesion appeared healed in 7 (41.2%) patients and partially healed in 9 (52.9%).

CONCLUSION

Internal fixation of lateral trochlear groove OCD with simultaneous lateral retinacular lengthening in adolescent athletes achieved satisfactory clinical and radiological outcomes. Therefore, this combined surgical technique could be considered an effective treatment for lateral trochlear groove OCD, with a high rate of return to sport.

Treatment of Patellofemoral Chondral Lesions Using Microfractures Associated with a Chitosan Scaffold: Mid-Term Clinical and Radiological Results

OBJECTIVE

To assess the clinical and radiological results of patellofemoral osteochondral lesions treated with microfractures associated with a chitosan scaffold.

DESIGN

A retrospective observational analytical study was performed. Fifteen patients with full-thickness patellofemoral osteochondral lesions were included. Quantity and quality of the reparation cartilage was assessed with the MOCART 2.0 score on a postoperative magnetic resonance imaging (MRI), and clinical outcomes were evaluated with pre- and postoperative Kujala score tests. Shapiro-Wilk test for normality was applied as well as Wilcoxon's signed rank test and Kruskal-Wallis H test for clinical scores within subjects and patella versus trochlea subgroups comparisons. Analysis of variance test was used for imaging subgroups comparison, with P < 0.05 defined as statistical significance.

RESULTS

Mean follow-up was 33.36 months (range 24-60 months). Postoperative Kujala scores improved an average of 19 points compared with the preoperative state (SE = 17.6; P < 0.001). No statistical difference was found through the clinical location assessment (P = 0.756), as well as the cartilage imaging assessment (P = 0.756). The mean MOCART 2.0 scale was 67.67 (range 50-85).

CONCLUSIONS

Treating full-thickness patellofemoral osteochondral lesions with microfractures associated with a chitosan scaffold proved to be effective regarding defect filling and symptomatic improvement.

Dysplastic Patellofemoral Joints Lead to a Shift in Contact Forces: A 3D-Printed Cadaveric Model

BACKGROUND

The distribution of contact forces across the dysplastic patellofemoral joint has not been adequately quantified because models cannot easily mimic the dysplasia of both the trochlea and the patella. Thus, the mechanical consequences of surgical treatments to correct dysplasia cannot be established.

PURPOSE/HYPOTHESIS

The objective of this study was to quantify the contact mechanics and kinematics of normal, mild, and severely dysplastic patellofemoral joints using synthetic mimics of the articulating surfaces on cadavers. We tested the hypothesis that severely dysplastic joints would result in significantly increased patellofemoral contact forces and abnormal kinematics.

STUDY DESIGN

Controlled laboratory study.

METHOD

Patellofemoral dysplasia was simulated in 9 cadaveric knees by replacing the native patellar and trochlear surfaces with synthetic patellar and trochlear implants. For each knee, 3 synthetic surface geometries (normal, showing no signs of dysplasia; mild, exemplifying Dejour type A; and severe, exemplifying Dejour type B) were randomized for implantation and testing. Patellar kinematics and the sum of forces acting on the medial and lateral patellar facets were computed for each knee and for each condition at 10° increments from 0° to 70° of flexion.

RESULTS

A pronounced lateral shift in the weighted center of contact of the lateral facet occurred for severely dysplastic knees from 20° to 70° of flexion. Compared with normal geometries, lateral patellar facet forces exhibited a significant increase only with mild dysplasia from 50° to 70° of flexion and with severe dysplasia at 70° of flexion. No measurable differences in medial patellar facet mechanics or joint kinematics occurred.

CONCLUSION

Our hypothesis was rejected: Severely dysplastic joints did not result in significantly increased patellofemoral contact forces and abnormal kinematics in our cadaveric simulation. Rather, severe dysplasia resulted in a pronounced lateral shift in contact forces across the lateral patellar facet, while changes in kinematics and the magnitude of contact forces were not significant.

CLINICAL RELEVANCE

Including dysplasia of both the patella and trochlea is required to fully capture the mechanics of this complex joint. The pronounced lateralization of contact force in severely dysplastic patellofemoral joints should be considered to avoid cartilage overload with surgical manipulation.

Correlation between Chondromalacia Patella and Patellofemoral Factors in Middle-Age Population: A Clinical, Functional, and Radiological Analysis

Background Despite higher incidence of patellofemoral pain (PFP) and consequently morbidity, the understanding about PF factors leading to PF arthritis is way lacking.

Material and Methods A prospective study of first 80 patients who were diagnosed with chondromalacia patella (CMP) on magnetic resonance imaging (MRI) divided into early and late CMP groups were evaluated clinically, radiologically, and in terms of functional outcome.

Results : Quadriceps angle, Clark’s test, and Insall–Salvati ratio results were nonsignificant despite greater values were observed in late CMP group, whereas trochlear morphology results (sulcus angle: 153:138 degrees and sulcus depth 3.9:5.4 mm) and clinical scores were significant in late CMP group (Kujala’s score: 61:78, whereas PF pain score: 43:25). Type-C patellar morphology was found in greater number in late CMP cohort.

Conclusion Trochlear and patellar morphologies along with clinical scores play a key role in understanding of the CMP.

Photobiomodulation as an Adjunctive Treatment to Physiotherapy for Reduction of Anterior Knee Pain in Combat Soldiers: A Prospective, Double-Blind, Randomized, Pragmatic, Sham-Controlled Trial

BACKGROUND AND OBJECTIVES

Anterior knee pain (AKP) is the most common knee pathology in athletes and occurs in 15% of army recruits of elite units during basic training. Of these, 50% are symptomatic 6 years later. Photobiomodulation (PBM) is a nonthermal red-to-near-infrared irradiation used for pain reduction of a variety of etiologies. This study was designed to determine whether addition of PBM to physiotherapy (PT) for AKP in combat soldiers is superior to PT alone.

STUDY DESIGN/MATERIALS AND METHODS

In this prospective, double-blind, sham-controlled, randomized clinical trial (NCT02845869), 26 combat soldiers/policemen (male:female, 15:11; body mass index [BMI] = 24.2 ± 3.9, n = 46 knees), with AKP due to overuse/load, received 4 weeks of PT + sham (PT + Sham) or active PBM (wavelength = 660 and 850 nm, pulsing = 2.5 Hz, LED power = 50 mW/cm² [local tissue/regional lymph nodes]; 810 nm continuous beam, laser cluster 6 W/cm² [analgesia] and laser pointer 4.75 W/cm² [trigger points]) (PT + PBM). The main outcome measures were subjective pain by visual analog scale (VAS) (0 [none]-100 [intolerable]) and functional disability by Kujala score (0 [worst]-100 [best]). Evaluations were carried out at baseline, end of treatments, and 3-month follow-up.

RESULTS

All participants completed the treatment protocol without any reported adverse device effects. Post-treatment pain was significantly reduced in the PT+PBM group, compared with baseline and sham (Δpain, VAS, mean ± SD: PT + PBM = -19 ± 23, P = 0.002; PT + Sham = -6 ± 21, P = 0.16; between groups, P = 0.032). At 3-month follow-up, pain reduction was similar between groups; however, the Kujala score was significantly improved only in the PBM-treated group (ΔKujala: PT + PBM = 11 ± 10, P = 0.003; PT + Sham = 5 ± 7, P = 0.059).

CONCLUSIONS

Addition of PBM to PT for AKP resulted in earlier reduction in pain and improved functionality, compared with PT alone. This noninvasive, nonpharmacologic, adjunctive therapeutic modality can be easily incorporated into team healthcare frameworks or end units and may lead to earlier return to competition or combat-level service. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Knowledge, confidence and learning needs of physiotherapists treating persistent knee pain in Australia and Canada: a mixed-methods study

Aim: To determine the knowledge and confidence of physiotherapists in managing knee osteoarthritis (OA) and patellofemoral pain (PFP); and explore their learning behaviors and preferences related to the management of these knee conditions.Methods: One hundred and sixteen Australian and Canadian Physiotherapists were recruited via social media, e-mail, and an online course. Part 1: Quantitative involved an online survey evaluating knowledge of evidence and confidence in providing treatments for knee OA and PFP. Part 2: Qualitative involved semi-structured interviews with 13 participants exploring current practice and learning needs, that were analyzed using an initial framework structured on interview questions, followed by inductive approach to identify additional themes.Results: Awareness regarding evidence supporting exercise for knee OA and PFP was good (89-96%), and qualitative themes indicated physiotherapists emphasized exercise-therapy and education. Perceived value of passive treatments and surgery varied. Preference for face-to-face workshops to address learning needs, alongside describing time and cost barriers to access them, emerged from qualitative findings. Online learning formats were viewed as convenient, but not as effective as face-to-face learning.Conclusion: Knowledge and confidence related to interventions for knee OA and PFP of Australian and Canadian physiotherapist participants broadly aligns with guidelines. Knowledge translation strategies focused on face-to-face workshops, supported by online education may help to bridge evidence-to-practice gaps.

Isolated Arthroscopic Lateral Retinacular Release for Lateral Patellar Compression Syndrome

Introduction: Evidence concerning the role of isolated lateral retinacular release (LRR) for lateral patellar compression syndrome (LPCS) dates back at least three decades. Appropriate indications, execution and outcomes still remain unclear and controversial. The present investigation analyzed the midterm result of isolated and arthroscopic LRR for LPCS in a cohort of patients who underwent such procedure at our institution. Material and methods: Patients undergoing isolated arthroscopic LRR for LPCS were identified retrospectively from our electronic database. All procedures were performed by two experienced surgeons. Patients with bony and/or soft tissues abnormalities, patellofemoral instability, moderate to severe chondral damage were not included. Patients with previous surgeries were not included, as were those who underwent combined interventions. Clinical scores and complications were recorded. Results: 31 patients were recruited in the present investigation. The mean follow-up was 86.0 ± 22.8 months. The mean age of the patients at the index operation was 34.2 ± 13.1 years. A total 55% (17 of 31) were women, and 58% (18 of 31) had involved the right knee. The mean hospitalization length was 3.5 ± 1.4 days. At a mean follow-up of 86.0 ± 22.8 months, the numeric rating scale (NRS) was 1.2 ± 0.8, the Kujala score was 91.3 ± 11.3, the Lysholm score was 93.1 ± 15.0, and the Tegner score was 5.0 ± 1.8. At the latest follow-up, 9 of 31 (29.0%) of patients experienced compilations. One patient (3.2%) had a post-operative hemarthrosis which was managed conservatively. Six patients (19.4%) reported a persistent sensation of instability, without signs of patellar dislocation or subluxation. One patient underwent an arthroscopic meniscectomy, and another patient an anterior cruciate ligament (ACL) reconstruction. Conclusion: isolated arthroscopic lateral retinacular release for lateral patellar compression syndrome is feasible and effective, achieving satisfying results at more than seven years following the procedure.

Longitudinal analysis of the contribution of 3D patella and trochlear bone shape on patellofemoral joint osteoarthritic features

To explore bone shape features that are associated with patellofemoral joint (PFJ) osteoarthritic features. Thirty subjects with PFJ degeneration (six males, 53.2 ± 9.8 years) and 23 controls (12 males, 48.1 ± 10.6 years) were included. Magnetic resonance (MR) assessment was performed to provide bone segmentation, morpholgocial grading, and cartilage relaxation times. In addition, subject self-reported symptoms were reported. Logistic regressions were used to identify the shape features that were associated with the presence and worsening of PFJ morphological lesions over 3 years, and worsening of self-reported symptoms. Statistical parametric mapping was used to evaluate the associations between shape features and cartilage relaxation times at 3 years. Results indicated that subjects with PFJ degeneration exhibited a trochlea with longer lateral condyle and shallower trochlear groove (adjusted odds ratio [OR] = 0.30; 95% confidence interval [CI]: 0.10, 0.86; P = .025). Subjects with worsening of PFJ degeneration exhibited a patella with equally distributed facets (adjusted OR = 3.14; 95% CI: 1.05, 9.37; P = .040) and lateral bump (adjusted OR = 0.14; 95% CI: 0.02, 0.83; P = .030). No shape features were associated with worsening of self-reported symptoms. Elevated T_1ρ and T₂ times at 3 years were associated with a patella with a lateral hook, equally distributed facets, round and thick as well as a trochlea larger in size (R = 0.38~0.46, P = .015~.025). The study demonstrated the ability of 3D statistical shape modeling to quantify patella and trochlear bone shape features that are associated with the presence and progression of PFJ osteoarthritic features.

Patellar Apprehension Is Reduced in Most but Not All Patients After Successful Patellar Stabilization

BACKGROUND

The clinical sign of patellar laxity and the associated symptom of apprehension are mainstays of the physical examination of patellofemoral instability. The apprehension test is widely used as a diagnostic tool and also as an outcome following patellofemoral stabilization surgery. Despite widespread use, the validity, reliability, and responsiveness of the apprehension test have not been established.

PURPOSE

The primary purpose was to evaluate patellar apprehension in patients with recurrent patellofemoral instability to determine if the apprehension test is valid, reliable, and responsive to change after medial patellofemoral ligament (MPFL) reconstruction. The secondary purposes were to concurrently validate patient-rated to surgeon-rated apprehension and to correlate patient-rated apprehension with pathoanatomic characteristics and quality-of-life scores.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 3.

METHODS

A total of 89 patients underwent an MPFL reconstruction and were assessed preoperatively and at 6, 12, and 24 months postoperatively. The patellar apprehension test was performed in neutral extension and 30° of knee flexion. Patient- and surgeon-rated apprehension were graded on a 10-cm visual analog scale (VAS), and the quality of the apprehension symptoms were recorded. Risk factors for patellofemoral instability were documented, and the Banff Patellofemoral Instability Score 2.0 (BPII 2.0) was used to measure disease-specific quality of life.

RESULTS

The patient-rated and surgeon-rated apprehension VAS scores were statistically significantly reduced from pre- to postoperatively (P < .001, large effect size) for the neutral extension and 30° of flexion apprehension tests. Postoperatively, over 56% of patients reported a negative apprehension test. Up to 15.7% of patients with positive preoperative apprehension did not demonstrate a reduction postoperatively. Patients consistently graded their apprehension symptoms higher in both quantity and quality than the surgeon. The intraclass correlation coefficient (ICC [2, k]) assessing the preoperative patient and surgeon VAS scores revealed moderate interrater reliability in neutral extension (r = 0.60) and weak interrater reliability in 30° of flexion (r = 0.42). The postoperative ICC (2, k) demonstrated strong interrater reliability for both neutral extension (r = 0.74) and 30° of flexion (r = 0.73). The symptoms of apprehension (physical, emotional, and/or physiological) decreased substantially after surgery. The correlation of postoperative patient-rated apprehension VAS and BPII 2.0 scores demonstrated that less residual patellar apprehension was associated with higher BPII scores in neutral extension (r = -0.35, P = .001). There were no statistically significant correlations revealed between the patient-rated postoperative apprehension VAS and pathoanatomic risk factors. BPII 2.0 scores improved pre- to postoperatively from a mean of 27.6 (SD, 15.7) to 74.3 (SD, 18.3). Three patients (3.4%) sustained a patellar dislocation postoperatively.

CONCLUSION

The patellar apprehension test demonstrated strong validity and responsiveness to change. Interrater reliability ranged from weak to strong. There was a statistically significant reduction in apprehension after patellofemoral stabilization in the majority of patients. Patients graded their apprehension symptoms significantly higher in both quantity and quality than the surgeon. Persistent patellar apprehension after stabilization was correlated with lower quality-of-life scores. No relationship could be found between persistent apprehension and patellofemoral risk factors. These results suggest that use of the apprehension tests as an outcome is inappropriate until further validation is performed.

Moment arm function dictates patella sagittal height anatomy: Rabbit epiphysiodesis model alters limb length ratios and subsequent patellofemoral anatomical development

Patellofemoral anatomical dysplasia is associated with patellofemoral instability and pain. The closure of the knee physis occurs at the same age as the peak incidence of patellofemoral dislocation. This study determined the effect on the patellofemoral anatomical development in a rabbit epiphysiodesis model. Twenty-four skeletally immature New Zealand White rabbits were divided into three groups (a) distal femur epiphysiodesis (FE) (b) proximal tibia epiphysiodesis (TE) (c) control; no epiphysiodesis (C) performed at 6 weeks of age. The primary endpoint was shape analysis using three-dimensional reconstructions of micro-computed tomographys (CTs) performed at 30 weeks of age. The limb length ratios (femur:tibia) were significantly different for both FE (mean 0.72, SD 0.0381, P < .001) and TE (mean 0.91, SD 0.0383, P < .001) treatment groups compared to control (mean 0.81, SD 0.0073). Patella height, as measured from the most distal point of the patella to the tibial joint surface (modified Caton-Deschamps measurement), was lower (baja) in the FE and higher (alta) for the TE, compared with the control group. Our findings suggest femoral and tibial shortening can influence the development of the patellofemoral joint, which may be dictated by moment arm function and is potentially responsible for the etiology of patella alta. Future studies are warranted to explore this association further with the view for the development of treatment options for patella alta in human patients.

A Validated, Automated, 3-Dimensional Method to Reliably Measure Tibial Torsion

BACKGROUND

Tibial torsion is a twist in the tibia measured as an angle between a proximal axis line and a distal axis line. Abnormal torsion has been associated with a variety of painful clinical syndromes of the lower limb. Measurements of normal tibial torsion reported by different authors vary by 100% (ranging from 20° to 42°), making it impossible to determine normal and pathological levels.

PURPOSE

To address the problem of unreliable measurements, this study was conducted to define an automated, validated computer method to calculate tibial torsion. Reliability was compared with current clinical methods. The difference between measurements of torsion generated from computed tomography (CT) and magnetic resonance imaging (MRI) scans of the same bone, and between males and females, was assessed.

STUDY DESIGN

Controlled laboratory study.

METHODS

Previous methods of analyzing tibial torsion were reviewed, and limitations were identified. An automated measurement method to address these limitations was defined. A total of 56 cadaveric and patient tibiae (mean ± SD age, 37 ± 15 years; range, 17-71 years; 28 female) underwent CT scanning, and 3 blinded assessors made torsion measurements by applying 2 current clinical methods and the automated method defined in the present article. Intraclass correlation coefficient (ICC) values were calculated. Further, 12 cadaveric tibiae were scanned by MRI, stripped of tissue, and measured using a structured light (SL) scanner. Differences between torsion values obtained from CT, SL, and MRI scans, and between males and females, were compared using t tests. SPSS was used for all statistical analysis.

RESULTS

When the automated method was used, the tibiae had a mean external torsion of 29°± 11° (range, 9°-65). Automated torsion assessment had excellent reliability (ICC, 1), whereas current methods had good reliability (ICC, 0.78-0.81). No significant difference was found between the torsion values calculated from SL and CT (P = .802), SL and MRI (P = .708), or MRI and CT scans (P = .826).

CONCLUSION

The use of software to automatically perform measurements ensures consistency, time efficiency, validity, and accuracy not possible with manual measurements, which are dependent on assessor experience.

CLINICAL RELEVANCE

We recommend that this method be adopted in clinical practice to establish databases of normal and pathological tibial torsion reference values and ultimately guide management of related conditions.

Can radiographic patellofemoral osteoarthritis be diagnosed using clinical assessments?

INTRODUCTION

The aim of this study was to determine whether participant characteristics and clinical assessments could identify radiographic osteoarthritis (OA) in individuals with clinically diagnosed, symptomatic patellofemoral osteoarthritis (PFOA).

METHODS

Participant characteristics and clinical assessments were obtained from 179 individuals aged 50 years and over with clinically diagnosed symptomatic PFOA, who were enrolled in a randomised trial. Anteroposterior, lateral, and skyline X-rays were taken of the symptomatic knee. The presence of radiographic PFOA was defined as "no or early PFOA" (Kellgren and Lawrence [KL] grade ≤1 in the PF compartment) or "definite PFOA" (KL grade ≥2). Diagnostic test statistics were applied to ascertain which participant characteristics and clinical assessments could identify the presence of definite radiographic PFOA.

RESULTS

A total of 118 participants (66%) had definite radiographic PFOA. Univariate analysis identified that older age (>61 years), female sex, higher body mass index (BMI) (>29 kg/m² ), longer pain duration (>2.75 years), higher maximum knee pain during stair ambulation (>47/100 mm), and fewer repeated single step-ups to pain onset (<21) were associated with the presence of definite radiographic PFOA. Multivariate logistic regression indicated that BMI, pain duration, and repeated single step-ups to pain onset were independently associated with radiographic PFOA and identified the presence of definite radiographic PFOA with an overall accuracy of 73%.

CONCLUSION

In individuals over 50 years of age with a clinical diagnosis of PFOA, higher BMI, longer pain duration, and fewer repeated single step-ups to pain onset increased the likelihood of radiographic PFOA. However, overall diagnostic accuracy was modest, suggesting that radiographic PFOA cannot be confidently identified using these tests.

A 3D-CT Analysis of Femoral Symmetry-Surgical Implications

BACKGROUND

Mirroring the image of the affected side is a widely used technique for surgical planning in orthopedic surgery, especially for fractures and custom-made prostheses. Our objective is to evaluate the three-dimensional symmetry of the femurs using finite element analysis and manual alignment.

METHODS

Using the computed tomography of 15 patients without lower limb pathology, 30 3D biomodels of their femurs were obtained. The error obtained through image manipulation was calculated and broken down into a rendering error and a manual overlay error. The Hausdorff-Besicovitch method was applied to obtain the total asymmetry. The manipulation error was theb subtracted from it to obtain the intrapersonal asymmetry.

RESULTS

The mean intrapersonal asymmetry was 0.93 mm. It was obtained by subtracting the error derived from rendering and alignment of 0.59 mm (SD 0.17 mm) from the overall mean error of 1.52 mm (SD 1.45).

CONCLUSIONS

Intrapersonal femoral asymmetry is low enough to use the mirror image of the healthy side as a reference for three-dimensional surgical planning. This type of planning is especially useful in deformity surgery when the objective of the surgery is not to restore only one specific parameter but to obtain a general functional morphology when a healthy contralateral femur is available.

Bipolar Osteochondral Allograft Transplantation of the Patella and Trochlea

OBJECTIVE

To evaluate clinical, functional, and radiographic outcomes of patients who underwent bipolar osteochondral allograft transplantation (OCAT) of the patellofemoral joint (PFJ).

DESIGN

Prospectively collected data on 18 knees who underwent fresh osteochondral allograft transplantation of the patella and trochlea by a single surgeon were reviewed. Inclusion criteria were: high-grade chondral lesions of PFJ (5 knees), or recurrent patella dislocations with trochlear dysplasia and chondral injury to the patella and/or trochlea (13 knees). Functional scores were obtained preoperatively and at follow-up appointments included Knee injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), Oxford, Cincinnati, Tenger-Lysholm, visual analogue scale (VAS)-pain, and Single Assessment Numeric Evaluation (SANE). Grafts were also evaluated using Osteochondral Allograft MRI Scoring System (OCAMRISS).

RESULTS

Three patients were lost to follow-up, leaving 4 knees in group 1, and 11 knees in group 2. Average age was 28.9 years (range 16-52 years). The average follow-up was 33.2 months (range 12-64 months). There was significant improvement of KOOS (from 38.7 to 83.1), IKDC (from 28.2 to 76.6), Tegner-Lysholm (from 38.3 to 88.3), Oxford (from 22.7 to 42.9), Cincinnati (from 35.1 to 83.6), VAS (from 71 to 17.9.), and SANE (from 43.3 to 83) (P < 0.0001). The OCAMRISS score for patella was 2.23 and for trochlea 4.69. There were no revisions or conversions to arthroplasty.

CONCLUSION

Bipolar OCAT of the patella and trochlea provide significant improvement in functional outcomes, relief from pain, activity level, and prevent recurrent instability.

Patellofemoral Cartilage Degeneration After Closed- and Open-Wedge High Tibial Osteotomy With Large Alignment Correction

BACKGROUND

Previous studies have reported patellofemoral cartilage degeneration and analyzed the factors affecting degeneration after open-wedge high tibial osteotomy (OWHTO). However, no studies have evaluated patellofemoral cartilage degeneration or examined the factors affecting degeneration after closed-wedge high tibial osteotomy (CWHTO).

PURPOSE

To investigate and compare patellofemoral cartilage degeneration after CWHTO and OWHTO via arthroscopic evaluation and to analyze the factors affecting the degeneration.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 54 CWHTOs and 50 OWHTOs were performed with first-look arthroscopy between 2013 and 2017 at one institution. Hardware removal and second-look arthroscopy were performed, on average, 30.2 months after CWHTO and 26.8 months after OWHTO (P = .178). Patient characteristics did not differ significantly between the groups. Radiographically, the mechanical axis, posterior tibial slope, and modified Blackburne-Peel ratio were evaluated. Arthroscopically, the percentage of patient with patellofemoral cartilage degeneration was evaluated according to the International Cartilage Repair Society grading system. Logistic regression analysis was used to identify the factors affecting patellofemoral cartilage degeneration in terms of demographics and the change of mechanical axis (correction angle), tibial posterior slope angle, and modified Blackburne-Peel ratio. The Anterior Knee Pain Scale was used for clinical comparison between the patellofemoral degenerative and nondegenerative groups.

RESULTS

No significant differences were observed in pre- and postoperative radiographic results between the CWHTO and OWHTO groups, except that the postoperative modified Blackburne-Peel ratio was significantly smaller among the OWHTOs. The percentage of patients with patellofemoral cartilage degeneration were 29.6% in the CWHTO group and 44% in the OWHTO group (P = .156) at second-look arthroscopy. The correction angle was the only significant factor affecting cartilage degeneration in the CWHTO group (odds ratio, 2.324; P = .013; cutoff value, 9.6°) and the OWHTO group (odds ratio, 1.440; P = .041; cutoff value, 10.1°). The postoperative Anterior Knee Pain Scale score was significantly lower in the patellofemoral degenerative group as compared with the nondegenerative group among the OWHTO group (81.6 vs 76.4; P = .039); among the CWHTO group, there was a lower tendency in the degenerative group, but this was without significance (81.1 vs 79.6; P = .367).

CONCLUSION

Patellofemoral cartilage degeneration progressed after CWHTO and OWHTO with large alignment correction. High tibial osteotomy should be selected with careful consideration of the osteoarthritic status of the patellofemoral joint and required correction angle, regardless of applying a closed- or open-wedge technique.

Anatomical femoral tunnel positioning in the medial patellofemoral ligament reconstruction: is the free-hand technique accurate?

Background

During medial patellofemoral ligament (MPFL) reconstruction, achieving anatomical positioning of the femoral and patellar origins is important for restoration of patellofemoral biomechanics. Although visual and manual detection can also be used to determine the femoral point of the MPFL, minimal research exists regarding accuracy of this method. Our aim was to evaluate the accuracy of free-hand method in determining the femoral point of the MPFL during surgery.

Methods

A prospective analysis was completed with 19 patients (20 knees), age ranging 15 to 39 years, in whom, three orthopedic surgeons with experience in knee procedures performed surgical reconstruction of the MPFL. MPFL femoral origin was accessed in a free-hand technique and a strict lateral view of the knee was then obtained. If the selected point was not considered appropriate, a better position was identified following the criteria set forth by Schottle.

Results

In a mean clinical follow-up of 2.3±1.3 years, anatomical point was achieved using the free-hand palpation method in seven knees (28.5%). Among the thirteen knees for whom the anatomical point was not attained without fluoroscopy, the mean error pattern found was 27.5%±8.6% for proximal (P-D axis) and 24%±6.3% for anterior in the posterior-anterior axis. The average error (difference between the marked point and the anatomical point) was 20.6%±5.9% (P=0.98) for the distal-proximal axis and 15.9%±6.1% (P=0.77) for the posterior-anterior axis.

Conclusions

The anatomical palpation technique showed low accuracy, even when performed by experienced surgeons. The most common error pattern observed was proximal and anterior.

Comparison of Patellofemoral Kinematics and Stability After Medial Patellofemoral Ligament and Medial Quadriceps Tendon-Femoral Ligament Reconstruction

BACKGROUND

There is a lack of evidence regarding the optimum extensor-sided fixation method for medial patellofemoral ligament (MPFL) reconstruction. There is increased interest in avoiding patellar drilling via soft tissue-only fixation to the distal quadriceps, thus reconstructing the medial quadriceps tendon-femoral ligament (MQTFL). The biomechanical implications of differing extensor-sided fixation constructs remain unknown.

HYPOTHESIS

The null hypothesis was there would be no differences between traditional MPFL reconstruction and MQTFL reconstruction with respect to resistance to lateral translation, patellar position, or patellofemoral contact pressures.

STUDY DESIGN

Controlled laboratory study.

METHODS

Nine adult knee specimens were mounted on a jig that applied static, physiologic loads to the quadriceps tendons. Patellar position and orientation, knee flexion angle, and patellofemoral pressure were recorded at 8 different flexion angles between 0° and 110°. Additionally, a lateral patellar excursion test was conducted wherein a load was applied directly to the patella in the lateral direction with the knee at 30° of flexion and subjected to 2-N quadriceps loads. Testing was conducted under 4 conditions: intact, transected MPFL, MQTFL reconstruction, and MPFL reconstruction. For MQTFL reconstruction, the surgical technique established by Fulkerson was employed. For MPFL reconstruction, a traditional technique was utilized.

RESULTS

The patellar excursion test showed no significant difference between the MQTFL and intact states with respect to lateral translation. MPFL reconstruction led to significantly less lateral translation (P < .05) than all other states. There were no significant differences between MPFL and MQTFL reconstructions with respect to peak patellofemoral contact pressure. MPFL and MQTFL reconstructions both resulted in increased internal rotation of the patella with the knee in full extension.

CONCLUSION

Soft tissue-only extensor-sided fixation to the distal quadriceps (MQTFL) during patella stabilization appears to re-create native stability in this time 0 cadaver model. Fixation to the patella (MPFL) was associated with increased resistance to lateral translation.

CLINICAL RELEVANCE

Evolving anatomic knowledge and concern for patellar fracture has led to increased interest in MQTFL reconstruction. Both MQTFL and MPFL reconstructions restored patellofemoral stability to lateral translation without increasing contact pressures under appropriate graft tensioning, with MQTFL more closely restoring native resistance to lateral translation at the time of surgery.

Effect of Trochlear Dysplasia on Commonly Used Radiographic Parameters to Assess Patellar Instability

BACKGROUND

Trochlear dysplasia (TD) is an important anatomic risk factor for patellar instability (PI). Several imaging-based risk factors for PI have been established, but it is unclear what effect TD has on these measurements, and the Dejour method of categorizing TD has been shown to be unreliable. The lateral trochlear inclination (LTI) is a quantifiable measurement of proximal trochlear morphology. Recently, a modified technique for measuring LTI referencing the posterior condylar angle has demonstrated near-perfect reliability and may serve as a new standard for quantifying TD.

PURPOSE/HYPOTHESIS

The purpose of this study was to evaluate how TD, expressed in terms of LTI, affects historically used measures of PI, including the sulcus angle (SA), tibial tuberosity to trochlear groove (TT-TG) distance, lateral patellar inclination (LPI), and Caton-Deschamps (CD) ratio. We hypothesized that lower LTI (ie, more dysplastic trochlea) will correlate with higher SA and TT-TG distances, increased patellar tilt, and more patella alta.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients aged 9 to 18 years treated for PI between January 2014 and August 2017 were queried. On magnetic resonance imaging (MRI), LTI, SA, LPI, and the TT-TG measured at the most proximal (pTT-TG) and distal (dTT-TG) aspects of the fully formed trochlear groove were measured on axial images. CD ratio was measured using sagittal MRI as well as lateral radiographs. All measurements were performed by 2 independent observers. Patients were included if there was a diagnosis of PI that was confirmed with a chart review and if there were appropriate imaging studies to analyze.

RESULTS

A total of 65 patients met inclusion criteria for this study. Average pTT-TG distance (15.7 ± 4.5 mm) was not significantly different from dTT-TG distance (15.7 ± 4.2 mm) (P = .94). LTI had a weak but significant inverse correlation with pTT-TG (r = -0.40; β = -0.15 mm; P < .001) and SA (r = -0.43; β = -0.478°; P < .001). There was a moderate and significant inverse correlation of LTI with dTT-TG (r = -0.593; β = -0.21 mm; P < .001) and with LPI (r = -0.69; β = -0.54°; P < .001). There was a weak but significant correlation between LTI and the MRI-based CD ratio (r = 0.279; β = 0.149; P = .005). Radiograph-based CD ratio did not show a significant correlation with LTI (r = -0.189; P = .135).

CONCLUSION

Smaller (ie, more dysplastic) LTI values correlated significantly with larger TT-TG, SA, LPI, and MRI-based CD ratio measurements. The relationship between SA and LTI is intuitive, but the relationship between LTI and the other analyzed variables suggests that they are dependent variables to TD and may not be consistent independent risk factors for PI. Together, these suggest that TD alters the radiographic interpretation of TT-TG and patellar tilt. The correlation between TD and patellar height is unclear and warrants further investigation.

Patellofemoral Cartilage Restoration: A Systematic Review and Meta-analysis of Clinical Outcomes

BACKGROUND

Many surgical options for treating patellofemoral (PF) cartilage lesions are available but with limited evidence comparing their results.

PURPOSE

To determine and compare outcomes of PF cartilage restoration techniques.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines were followed by utilizing the PubMed, EMBASE, and Cochrane Library databases. Inclusion criteria were clinical studies in the English language, patient-reported outcomes after PF cartilage restoration surgery, and >12 months' follow-up. Quality assessment was performed with the Coleman Methodology Score. Techniques were grouped as osteochondral allograft transplantation (OCA), osteochondral autograft transfer (OAT), chondrocyte cell-based therapy, bone marrow-based therapy, and scaffolds.

RESULTS

A total of 59 articles were included. The mean Coleman Methodology Score was 71.8. There were 1937 lesions (1077 patellar, 390 trochlear, and 172 bipolar; 298 unspecified). The frequency of the procedures was as follows, in descending order: chondrocyte cell-based therapy (65.7%), bone marrow-based therapy (17.2%), OAT (8%), OCA (6.6%), and scaffolds (2.2%). When compared with the overall pooled lesion size (3.9 cm²; 95% CI, 3.5-4.3 cm²), scaffold (2.2 cm²; 95% CI, 1.8-2.5 cm²) and OAT (1.5 cm²; 95% CI, 1.1-1.9 cm²) lesions were smaller (P < .001), while chondrocyte cell-based therapy lesions were larger (4.7 cm²; 95% CI, 4.1-5.3 cm²; P = .039). Overall, the instability pool was 11.9%, and the anatomic risk factors pool was 32.1%. Statistically significant improvement was observed on at least 1 patient-reported outcome in chondrocyte cell-based therapy (83%), OAT (78%), OCA (71%), bone marrow-based therapy (64%), and scaffolds (50%). There were no significant differences between any group and the overall pooled change in International Knee Documentation Committee score (30.2; 95% CI, 27.4-32.9) and Lysholm score (25.2; 95% CI, 16.9-33.5). There were no significant differences between any group and the overall pooled rate in minor complication rate (7.6%; 95% CI, 4.7%-11.9%) and major complication rate (8.3%; 95% CI, 5.7%-12.0%); however, OCA had a significantly greater failure rate (22.7%; 95% CI, 14.6%-33.4%) as compared with the overall rate (6.8%; 95% CI, 4.7%-9.5%).

CONCLUSION

PF cartilage restoration leads to improved clinical outcomes, with low rates of minor and major complications. There was no difference among techniques; however, failures were higher with OCA.

Prediction of patellofemoral joint kinematics and contact through co-simulation of rigid body dynamics and nonlinear finite element analysis

Joint-level rigid body dynamics simulations, when coupled with tissue-level finite element analyses, can simultaneously provide movement and tissue deformation metrics to understand mechanical interactions within the joint on a multi-scale level. In this study, a co-simulation workflow of a joint-level rigid body model that predicts the relative motion as a function of the non-linear cartilage response predicted by a non-linear implicit finite element solver is presented. Predictions are compared to in-vitro measurements (The Open Knee(s) project) in terms of the mean error and level-of-agreement: pressure_error = 0.46 MPa (level-of-agreement, -0.23 - 1.1 MPa); area_error = -89 mm² (level-of-agreement, -280 - 98 mm²) and contact force_error = 93 N (level-of-agreement, 7.8 - 180 N). The automated co-simulation control algorithm enables multiscale coupling between joint and tissue-level models with real-time two-way communication as opposed to the traditional feed-forward approach of multi-scale models.

An Expert Consensus Statement on the Management of Large Chondral and Osteochondral Defects in the Patellofemoral Joint

Background

Cartilage lesions of the patellofemoral joint constitute a frequent abnormality. Patellofemoral conditions are challenging to treat because of complex biomechanics and morphology.

Purpose

To develop a consensus statement on the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint using a modified Delphi technique.

Study Design

Consensus statement.

Methods

A working group of 4 persons generated a list of statements related to the functional anatomy, indications, donor graft considerations, surgical treatment, and rehabilitation for the management of large chondral and osteochondral defects in the patellofemoral joint to form the basis of an initial survey for rating by a group of experts. The Metrics of Osteochondral Allografts (MOCA) expert group (composed of 28 high-volume cartilage experts) was surveyed on 3 occasions to establish a consensus on the statements. In addition to assessing agreement for each included statement, experts were invited to propose additional statements for inclusion or to suggest modifications of existing statements with each round. Predefined criteria were used to refine statement lists after each survey round. Statements reaching a consensus in round 3 were included within the final consensus document.

Results

A total of 28 experts (100% response rate) completed 3 rounds of surveys. After 3 rounds, 36 statements achieved a consensus, with over 75% agreement and less than 20% disagreement. A consensus was reached in 100.00% of the statements relating to functional anatomy of the patellofemoral joint, 88.24% relating to surgical indications, 100.00% relating to surgical technical aspects, and 100.00% relating to rehabilitation, with an overall consensus of 95.5%.

Conclusion

This study established a strong expert consensus document relating to the functional anatomy, surgical indications, donor graft considerations for osteochondral allografts, surgical technical aspects, and rehabilitation concepts for the management of large chondral and osteochondral defects in the patellofemoral joint. Further research is required to clinically validate the established consensus statements and better understand the precise indications for surgery as well as which techniques and graft processing/preparation methods should be used based on patient- and lesion-specific factors.

Risk Factors for Opioid Use After Patellofemoral Stabilization Surgery: A Population-Based Study of 1,316 Cases

BACKGROUND

Orthopaedic surgeons remain the third-highest group of opioid prescribers among physicians in the United States, accounting for 8% of all opioid prescriptions. The purpose of this study was to identify risk factors for opioid consumption and opioid prescription refills after patellofemoral stabilization surgery. We hypothesized that preoperative opioid use and younger age would be independent risk factors for postoperative opioid use.

METHODS

Patients undergoing primary patellar stabilization surgery between 2007-2017 in the Humana Inc. administrative claims database were identified using Current Procedural Terminology (CPT) codes for patellofemoral stabilization procedures (CPT-27420, 27422, 27427,27418). Patients were categorized into opioid naive (N-OU) and those who filled opioid prescriptions within 3 months prior to surgery (OU). Patients in the OU cohort were further categorized into those who filled prescriptions at 1-3 months before surgery (C-OU) and those who filled opioid prescriptions only in the month preceding surgery (A-OU). Descriptive statistics and multivariate analyses were performed to identify risk factors for postoperative opioid use at 3 and 12 months using the open-source R software (www.r-project.org) housed within PearlDiver.

RESULTS

A total of 1,316 eligible patients were included. One year postoperatively, there was a greater risk of opioid consumption in the OU cohort (OU vs N-OU: 22.2% vs 4.1%; Relative Risk [RR]: 1.233; 95% CI: 1.172- 1.298; P< 0.0001). C-OU (OR: 5.74; 95% CI: 3.75- 8.9; P< 0.0001), obesity (OR: 1.76; 95% CI: 1.14- 2.69; P = 0.0099), and preoperative diagnosis of depression or anxiety (OR: 1.83; 95% CI: 1.01- 3.25; P = 0.0435) were independent risk factors for opioid use at 12 months postoperatively. Younger age (age <30) was associated witha lower risk of opioid use at 3 months (OR: 0.3, 95% CI: 0.21- 0.44; P< 0.0001) and 12 months (OR: 0.29; 95% CI: 0.17- 0.46; P< 0.0001) postoperatively.

CONCLUSIONS

Preoperative opioid utilization significantly increased opioid prescription filling following patellofemoral stabilization surgery. Patient-specific variables including obesity and preoperatively diagnosed depression or anxiety also increased the risk of postoperative opioid utilization. Given the relatively young age and high activity level of patients undergoing patellofemoral stabilization surgery, heightened awareness of patient-specific factors must be considered when selecting appropriate pain management regimens postoperatively.Level of Evidence: III.