Current concepts of lateral patella dislocation

ABCA6 Regulates Chondrogenesis and Inhibits Joint Degeneration via Orchestrated Cholesterol Efflux and Cellular Senescence

Patellar dysplasia (PD) can cause patellar dislocation and subsequent osteoarthritis (OA) development. Herein, a novel ABCA6 mutation contributing to a four-generation family with familiar patellar dysplasia (FPD) is identified. In this study, whole exome sequencing (WES) and genetic linkage analysis across a four-generation lineage presenting with six cases of FPD are conducted. A disease-causing mutation in ABCA6 is identified for FPD. Further analyses reveal a consistent correlation between ABCA6 expression downregulation and PD occurrence, chondrocyte degeneration, and OA onset. Moreover, ABCA6-KO mice demonstrate severe knee joint degeneration and accelerated OA progression. Besides, synovial mesenchymal stem cells (SMSCs) are extracted from WT, ABCA6-/+, and ABCA6-/- mice to create chondrogenic organoids in vitro, confirming ABCA6 deficiency can lead to chondrocyte degeneration via modulating cell cycle and activating cellular senescence. Moreover, transcriptome and metabolomic sequencing analysis on ABCA6-KO chondrocytes unveils that the ABCA6 deficiency inhibits cholesterol efflux, leading to intracellular cholesterol accumulation and subsequent cellular senescence and impaired chondrogenesis.A disease-causing mutation of ABCA6 is identified for FPD. ABCA6 is correlated with PD occurrence and subsequent OA progression. ABCA6 can serve as a potential target in chondrogenesis and OA treatment by orchestrated intracellular cholesterol efflux and delayed cellular senescence.

Predicting Surgical Outcomes in Patients With Recurrent Patellar Dislocations

Background

A lateral dislocation of the patella is a common injury in adolescents and young adults that is largely caused by underlying anatomic risk factors. Surgically managed patients have a significantly lower risk of recurrent dislocations. However, determining the optimal surgical treatment remains a challenge, with patients sometimes undergoing multiple surgical procedures before achieving successful stabilization.

Purpose

To computationally evaluate patients who have undergone multiple surgical procedures to treat recurrent lateral patellar dislocations and predict their clinical outcomes.

Study Design

Controlled laboratory study.

Methods

Our cohort consisted of 16 patients with trochlear dysplasia and recurrent lateral patellar dislocations. We used magnetic resonance imaging to create 3-dimensional patient-specific finite element models of the knee joint and evaluated patellofemoral stability before and after surgery. We applied these models to computationally predict the clinical outcome of each surgical procedure. We simulated a knee extension activity coupled with external tibial torsion to assess patellofemoral stability. We also included a healthy control group of 12 participants in the computational evaluation. Finally, we developed and trained a logistic regression model based on anatomic risk factors and applied this model to classify whether patients had a likelihood of a dislocation to efficiently differentiate between surgical outcomes.

Results

Of 12 control, 12 preoperative, and 9 postoperative scans, the finite element model correctly predicted 29 of 33 surgical outcomes (87.9% accuracy). Postoperative simulations predicted patellofemoral stability metrics similar to those of the control group. Specifically, patients after trochleoplasty were associated with increased constraint force on the patellar lateral facet and lower involvement of the medial patellofemoral ligament. The logistic regression model demonstrated 81.8% accuracy in classification.

Conclusion

Preliminary results are promising, but an improvement of the model and a larger clinical dataset are necessary to increase accuracy and comprehensively validate model performance.

Clinical Relevance

The aim of this study was to provide surgeons with a useful computational tool that can predict the likelihood of a patellar dislocation and differentiate, before a clinical intervention, between successful versus unsuccessful surgery to determine the optimal treatment pathway for individual patients.

Age Is a Key Factor Influencing the Choice of Treatment for Primary Patellar Dislocation: A Systematic Review and Meta-analysis

Primary patellar dislocation has a certain recurrence rate after either conservative or surgical treatment, and the optimal treatment for patients with primary patellar dislocation of different ages remains unclear. This study aims to compare the clinical efficacy of surgical and conservative treatments for primary patellar dislocation across different age groups. According to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) checklist, we conducted a systematic search for randomized controlled trials. We searched the PubMed, EMBASE, Cochrane Library, and Web of Science databases for randomized controlled trials of primary patellar dislocation treated surgically or conservatively up to January 2023. Data searching, extraction, analysis, and quality assessment were carried out in accordance with the Cochrane Collaboration guidelines. A total of nine studies with 433 patients were included in our study. There was no statistically significant difference between the two treatment modalities in terms of Kujala score, pain score, patient satisfaction, reoperation, and Tegner score. The rate of re-dislocation after surgical treatment is lower than that after conservative treatment. Subgroup analysis based on mean age showed that when the age was >20 years, Kujala scores were higher after surgical treatment than after conservative treatment (p < 0.0001, 95% confidence interval [CI] = 10.41-21.30). When the age was ≤20 years, the difference in Kujala scores between the two treatment modalities was not statistically significant. When the age was >20 years, the recurrence rate of patellar dislocation was lower after surgical treatment than after conservative treatment (p = 0.009, 95% CI = 0.08-0.70). When the age was ≤20 years, the difference in the recurrence rate of patellar dislocation between the two treatment modalities was not statistically significant. When the age of patients with primary patellar dislocation is ≤20 years, both surgical and conservative treatments result in similar clinical outcomes. When the age is >20 years, better clinical outcomes can be achieved by opting for surgical treatment. Therefore, surgery may be a better option for patients with primary patellar dislocation whose age is >20 years.

The relationship between joint hypermobility and patellar instability: A systematic review

Introduction

Hypermobility describes the movement of joints beyond normal limits. Whether hypermobility predisposes to patellar instability is yet to be established. We aimed to determine if joint hypermobility leads to an increased risk of patellar instability, and to evaluate outcomes of treatment for patellar instability in those who exhibit hypermobility.

Methods

Published and unpublished literature databases were searched to September 7, 2023. Studies comparing prevalence of patellar dislocation/differences in treatment outcomes in patients with and without hypermobility were included.

Results

We identified 18 eligible studies (4,391 patients). The evidence was low in quality. A case series on 82 patients found that there was a relationship between generalised joint laxity and patellar instability. This was corroborated by a study comparing 104 patients with patellar dislocation to 110 patients without. Prevalence of generalised joint laxity was six time higher in the former (64.4% vs 10.9%, p < 0.001).Five studies found surgical intervention aimed at correcting patellar dislocation in patients with idiopathic hypermobility led to satisfactory outcomes. There was conflicting evidence regarding if hypermobile patients have worse outcomes than non-hypermobile patients following medial patellofemoral ligament reconstruction (MPFLR) in two studies. In addition, this procedure had a 19.1% failure rate in patients with Ehlers Danlos Syndrome (EDS), with hypermobility associated with a higher failure rate (p = 0.03). One study showed the type of graft used made no difference in outcome scores or re-dislocation rates (p > 0.5). Another study had 7/31 (22.6%) autografts which failed, compared to 2/16 allografts (12.5%) (p = 0.69).

Conclusion

Joint hypermobility is a risk factor for patellar instability. Identification of at-risk groups may aid prevention of dislocations and allow for appropriate treatment. Patients with EDS experience poor outcomes following patellar stabilization surgery, with post-operative monitoring required.

Long-term results after medial patellotibial ligament reconstruction for the treatment of patellofemoral instability

PURPOSE

To evaluate long-term clinical outcomes and redislocation rate after medial patellotibial ligament reconstruction.

MATERIALS AND METHODS

A total of 26 knees with mean age 26.3 ± 10.6 years (25 patients, 7 males and 18 females) treated for patellar instability (at least two objective dislocations) with medialization of the patellar tendon medial third were evaluated with an intermediate clinical follow-up (FU) at a mean of 6.5 ± 2.1 years and with a final telephone interview follow-up at mean of 15.6 ± 2.5 years (11.4-20.1). Western Ontario and MacMaster Universities Osteoarthritis Index (WOMAC), Kujala, Visual Analog Scale (VAS) for pain and Tegner activity scores were used. Information about further redislocation and knee surgery was also collected.

RESULTS

All the clinical scores had a significant improvement compared to preoperative status (WOMAC pre-op 55.9 ± 27.2 vs. WOMAC final FU 80.8 ± 22.2; KUJALA pre-op 41.0 ± 24.0 vs. KUJALA final FU 77.2 ± 24.1; VAS pre-op 6.0 ± 3.1 vs. VAS final FU 3.44 ± 2.35; TEGNER pre-op 2.1 ± 2.0 vs. TEGNER final FU 3.6 ± 1.8; p < 0.001), and the outcomes remained stable at the final follow-up compared to the intermediate follow-up (p > 0.05). A total of 4 knees had at least one redislocation at the final follow-up, while 3 knees underwent total knee replacement surgery. The redislocation-survival rate at 5 years is 92%, meanwhile is 84% at 10 and 15 years.

CONCLUSIONS

MPTL reconstruction produced good clinical results and a survival rate of 84% at a mean of 16 years follow-up and could be considered as associated procedure in case of patellofemoral instability.

LEVEL OF EVIDENCE

Level IV.

Normal values of the axial patellotrochlear overlap on MRI: Good correlation with patellotrochlear index in patients with no patellofemoral pathology

BACKGROUND

There are several imaging-based measurements for patellofemoral height, which are obtained from sagittal images. However, these methods can be misleading with sagittal oblique slices and when the patella is tilted and/or chronically subluxated. This study aimed to describe a simple method of measuring patellar height using axial patellotrochlear overlap (APTO) on MRI.

METHODS

A retrospective observational study of 97 knees from 251 patients, excluding those with fractures, massive effusion, or patellofemoral conditions. APTO was measured as follows: (1) patellar length (P) - expressed as the number of axial images showing patellar articular cartilage; (2) trochlear overlap (T) - the number of axial images showing the overlap between patellar articular cartilage and articular cartilage of the lateral trochlea. APTO is the ratio T/P. All measurements were performed independently by six raters on two separate occasions. The raters were two orthopaedic consultants, one knee surgery fellow, two consultant musculoskeletal radiologists, and one radiology fellow. The conventional patellotrochlear index (PTI) was measured as a control for all patients by a senior musculoskeletal radiologist.

RESULTS

The mean APTO value was 36.7% (range 14.2-66.6; standard deviation 11.4). There was a positive correlation with the PTI, Pearson correlation coefficient: 0.76, P < 0.001. Intra-observer reliability was good (intraclass correlation coefficient(ICC): 0.66, 95% confidence interval (CI) 0.54, 0.76, P < 0.001). Inter-observer reliability was fair (ICC: 0.51, 95% CI 0.41, 0.6, P < 0.001).

CONCLUSIONS

APTO was shown to be a reliable measurement of patellar height and correlated with existing PTI for patellar height. Measurement of APTO on MRI could be a reliable alternative for the evaluation of patellar height. However, further studies are required to assess its validity in patients with patellofemoral pathology.

Evaluation of Differences in Patellar Height After Patellar Stabilization Procedures Not Intended to Address Patella Alta: A Multicenter Study

Background

Recent studies have reported conflicting results as to whether isolated medial patellofemoral ligament reconstruction (MPFLr) leads to decreased patellar height.

Purpose

To investigate if patellar stabilization surgery not intended to address patella alta influences patellar height.

Study Design

Cohort study; Level of evidence, 3.

Methods

A multicenter retrospective chart review was conducted, and patients who underwent MPFLr, medializing tibial tuberosity osteotomy (TTO), and/or trochleoplasty between 2016 and 2020 were included. The Caton-Deschamps index (CDI) was calculated from radiographs obtained preoperatively, 2 weeks postoperatively, and 3 months postoperatively. The preoperative CDI value was compared with the 2-week postoperative and 3-month postoperative values according to stabilization procedure (isolated MPFLr, isolated TTO, MPFLr + TTO, MPFLr + trochleoplasty, and MPFLr + trochleoplasty + TTO) using the paired t test. Analyses of the 1-bundle versus 2-bundle MPFLr technique and the presence of lateral retinacular release or lateral retinacular lengthening were conducted on the isolated MPFLr and combined MPFLr + TTO cohorts.

Results

A total of 356 knees were included. Statistically significant pre- to postoperative decreases in CDI were seen in all stabilization procedures analyzed (P≤ .017 for all). Within the isolated MPFLr cohort, this significant decrease was seen at 2 weeks postoperatively with the 2-bundle technique (ΔCDI = -0.09; P < .001) but not with the 1-bundle technique (ΔCDI = -0.01; P = .621).

Conclusion

The different surgical techniques analyzed in the current study affected patellar height, even when a distalizing TTO was not performed. The decrease was dependent on surgical technique, with a 2-bundle MPFLr leading to a statistically significant decrease and a 1-bundle MPFLr effecting no change.

Double-Limb Graft Versus Single-Limb Graft Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation: A Meta-analysis of Randomized Controlled Trials and Cohort Studies

BACKGROUND

The medial patellofemoral ligament (MPFL) is the most important stabilizer of lateral dislocation of the patella. Single-limb (SL) and double-limb (DL) graft MPFL reconstructions have been increasingly used to treat recurrent patellar dislocations, but the clinical efficacy of SL versus DL graft MPFL reconstructions remains controversial owing to the inconsistent conclusions of previous studies.

PURPOSE

This study aimed to compare the clinical outcomes of SL and DL graft MPFL reconstructions for patients with recurrent patellar dislocation by conducting a meta-analysis of randomized controlled trials and cohort studies.

STUDY DESIGN

Meta-analysis; Level of evidence, 3.

METHODS

PubMed, Embase, Web of Science, and the Cochrane Library were searched for relevant studies. The retrieval time was up to July 25, 2022. Two evaluators independently screened the literature, extracted data, and assessed the methodological quality of the enrolled studies. Meta-analysis was conducted using RevMan 5.4 software.

RESULTS

A total of 4 randomized controlled trials and 3 cohort studies with 451 patients were included. The joint stability and functional scores in both groups improved significantly from baseline. When compared with SL graft reconstruction, DL graft reconstruction provided reduced recurrent instability (P = .01), anterior patella-related pain (P = .02), and patellar lateral shift rate (P = .02). Regarding functional recovery, patients undergoing DL graft reconstruction presented better scores on the Kujala (P < .001), Tegner (P = .009), and International Knee Documentation Committee (IKDC) (P < .001) but similar Lysholm scores as compared with SL graft reconstruction. No statistically significant difference was found between the techniques in the reduction of the patellar tilt angle, complications other than anterior patella-related pain, or postoperative pain.

CONCLUSION

When compared with SL graft MPFL reconstruction, DL graft MPFL reconstruction yielded better outcomes in terms of postoperative recurrent instability, anterior patella-related pain, patellar lateral shift rate, Kujala score, Tegner score, and IKDC score. The amount of high-quality evidence is insufficient, so this conclusion should be interpreted with caution.

Reliability of the TT-TG Index Versus TT-TG Distance on MRI: Morphometric Analyses in Asian Children and Adolescents

Background

The tibial tuberosity-trochlear groove (TT-TG) distance measured on magnetic resonance imaging (MRI) is commonly used to decide the treatment for patellar instability; however, the patient's joint size is not considered in this measurement. The TT-TG index has been proposed as a knee size-adjusted measurement for tibial tuberosity location.

Purpose

To evaluate the reliability of the TT-TG index compared with the TT-TG distance by analyzing variations in measurement according to age and sex in a pediatric Asian population.

Study Design

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

Methods

A total of 698 knee MRI scans were collected in patients between 4 and 18 years of age who did not have any patellofemoral problems. Patient age, sex, height, and weight were recorded. The scans were divided into 5 groups according to patient age (4-6 years, 46 scans; 7-9 years, 56 scans; 10-12 years, 122 scans; 13-15 years, 185 scans; and 16-18 years, 289 scans); MRI scans were also divided by sex (497 male, 201 female). Three independent observers measured the TT-TG distance and TT-TG index on each scan, and age- and sex-based differences in the measurements were evaluated after adjusting for body mass index (BMI). The reliability of the measurements was calculated with the intraclass correlation coefficient (ICC).

Results

Good to excellent inter- and intraobserver agreement was found for TT-TG distance (ICC, 0.74) and TT-TG index (ICC, 0.88). The TT-TG distance was significantly different among the groups and increased with age, while variations in the TT-TG index were minimal between age groups and sexes. This finding was also consistent after compensating for the effect of BMI.

Conclusion

The TT-TG distance changed with age, while the TT-TG index was relatively constant. Therefore, the TT-TG index may be more reliable and effective for diagnosing and planning treatment, especially in children and adolescents.

3D Printed Models of Trochlear Dysplasia and Trochleoplasty Simulation for Trainee Education

Trochlear dysplasia is a major contributor to patellofemoral instability and subsequent failure of isolated soft tissue reconstruction procedures in the treatment of recurrent patellar dislocation and/or subluxation. Trochleoplasty procedures aim to address abnormal osseous trochlear morphologic factors that contribute to patellar maltracking. However, teaching these techniques is limited by the lack of reliable training models for trochlear dysplasia and trochleoplasty simulation. Although a cadaveric knee model of trochlear dysplasia for trochleoplasty simulation has been recently described, cadaveric knees are less amenable for use in trochleoplasty planning and surgeon training because of the absence of reliable, natural dysplastic anatomic relationships, such as suprapatellar spurs due to the rarity of dysplastic cadavers and the high cost of cadaveric specimens. Furthermore, readily available sawbone models represent "normal" osseous trochlear morphology and are difficult to modify and bend due to their material composition. Given this, we have developed a cost-effective, reliable, and anatomically accurate three-dimensional (3D) knee model of trochlear dysplasia for trochleoplasty simulation and trainee education.

A Patella-Sided Tensioning Technique for Medial Patellofemoral Ligament Reconstruction

Reconstruction of the medial patellofemoral ligament (MPFL) is a common procedure for treatment of recurrent patellofemoral instability. Over the last two decades, multiple surgical techniques for MPFL reconstruction have been described with no clear consensus on a superior reconstruction technique. Appropriate graft tensioning is one of the most important factors for a successful MPFL reconstruction. Overtensioning of the MPFL graft can lead to patellofemoral joint overload and undertensioning can lead to recurrent instability. Current literature demonstrates descriptions of MPFL reconstruction with final graft tensioning performed off of the femoral side. We describe a technique in this article for performing final graft tensioning from the patellar side, which gives the surgeon an option for intraoperative tension adjustments after evaluating patellar tracking.

Is Patellar Instability a Contraindication to Semiextended Tibial Nailing?: A Case Report

CASE

We report a 40-year-old woman with undiagnosed patellofemoral instability that worsened 8 months after intramedullary nailing of a distal left tibia fracture in the semiextended position through a partial medial parapatellar approach. Patella stability and asymptomatic knee function were restored after IM nail removal, medial patellofemoral ligament repair, and left tibial tubercle transposition.

CONCLUSION

The optimal surgical approach for tibial IM nailing in patients with chronic patellar instability has not been described. Clinicians should be cognizant of the potential for worsening patellofemoral instability in these patients when using the medial parapatellar approach in the semiextended position.

Combined Medial Patellofemoral Ligament, Medial Quadriceps Tendon-Femoral Ligament, and Medial Patellotibial Ligament Reconstruction for Patellar Instability: A Technical Note

Lateral patellar dislocations often occur in a young, athletic population of recurrent dislocators with generalized laxity and an interest in returning to an active lifestyle. A recent appreciation for the distal patellotibial complex has directed surgeons toward attempting to re-create the native anatomy and knee biomechanics during medial patellar reconstructive procedures. By reconstructing the medial patellotibial ligament (MPTL) in addition to the medial patella-femoral ligament (MPFL) and medial quadriceps tendon-femoral ligament (MQTFL), the current article describes a potentially more stable construct that can be utilized in patients with subluxation with the knee in full extension, patellar instability with the knee in deep flexion, genu recurvatum, and generalized hyperlaxity. Additionally, the current technique utilizes a tibialis anterior allograft. The purpose of this Technical Note is to describe, in detail, the current authors' technique for a combined MPFL, MQTFL, and MPTL reconstruction.

Editorial Commentary: From Lateral Release and Medial Plication to Complex Medial Patellofemoral Ligament Reconstruction Techniques: Medial Quadriceps Tendon Femoral Ligament Reconstruction Is the Most Anatomic Repair

Patella instability and dislocation are common in younger patients, and 1 in 5 patients are at risk of recurrent dislocations. Conservative treatment should be considered for first dislocations unless other concomitant injuries are present. Historically, lateral patella release and medial plication techniques were used for repair but have been superseded by medial patellofemoral ligament reconstruction. Overconstraint is a potential problem and often related to nonanatomic femoral tunnel position and graft tension, which could result in increased patellar contact pressures and graft failure. The medial quadriceps tendon-femoral ligament reconstruction technique (MQTFL) avoids patellar tunnels without the risk of patella fracture. When comparing medial patellofemoral ligament, MQTFL, and the combination of both techniques in a cadaver model, MQTFL resulted in less constraint with no differences for patellar contact pressures. Medial quadriceps tendon femoral ligament reconstruction is the most anatomic repair.

Distal femur varus-producing osteotomy: An updated review of patellofemoral implications and clinical outcomes

Background: Recent evidence seems to suggest the effectiveness of distal femur varus osteotomy in the management of patellofemoral instability in the setting of genu valgum. However, literature on this subject remains scarce and consists mostly of small case series. Hypothesis: This study aims to systematically review the literature on varus-producing distal femur osteotomy and critically analyze its implications on patellofemoral kinematics and stability. Results: The statistical analysis revealed that this surgery is able to restore a mechanical angle (mean hip–knee–ankle (HKA): 0.22°) and to improve the main clinical outcomes (Kujala score, Knee injury and Osteoarthritis Outcome Score, visual analog scale) after a mean follow up of 2.5 years. An objective of the present review was to investigate the mechanical implications of femoral osteotomy on the patellofemoral biomechanics. Indeed, the statistical analysis demonstrated changes after surgery in the main patella-femoral radiological angles (modified Insall–Salvati index, Caton–Deschamps index, Blackburne–Peel index). Interestingly the overcorrection of the mechanical axis (HKA), resulting in varus, had similar outcomes compared to studies that obtained a mechanical axis. Level of Evidence: Level II study.

A 20-Year Retrospective Study of Children and Adolescents Treated by the Three-in-One Procedure for Patellar Realignment

BACKGROUND

Patellar instability is the most common disorder of the knee during childhood and adolescence. Surgical treatment significantly reduces the rate of redislocation, but the underlying pathologies and pattern of instability may affect the results. We aimed to report the clinical and functional outcomes of the three-in-one procedure for patellar realignment in a cohort of skeletally immature patients with or without syndromes and various patterns of chronic patellar instability.

METHODS

We retrospectively investigated 126 skeletally immature patients (168 knees) affected by idiopathic or syndromic patellar instability, who underwent patella realignment through a three-in-one procedure. We classified the instability according to the score proposed by Parikh and Lykissas.

RESULTS

Patellar dislocation was idiopathic in 71 patients (94 knees; 56.0%) and syndromic in 55 (74 knees; 44.0%). The mean age at surgery was 11.5 years (range 4-18) and was significantly lower in syndromic patients. Syndromic patients also exhibited more severe clinical pattern at presentation, based on the Parikh and Lykissas score. The mean follow-up was 5.3 years (range 1.0-15.4). Redislocation occurred in 19 cases, with 10 cases requiring further realignment. The Parikh and Lykissas score and the presence of congenital ligamentous laxity were independent predictors of failure. A total of 22 knees in 18 patients required additional surgical procedures. The post-operative Kujala score was significantly lower in patients with syndromic patellar instability.

CONCLUSIONS

The type of instability and the presence of underlying syndromes negatively affect the rate of redislocation and the clinical and functional outcome following patellar realignment through the three-in-one procedure. We recommend the consideration of alternative surgical strategies, especially in children with severe syndromic patellar dislocation.

Factors That Affect the Magnitude of Tibial Tubercle-Trochlear Groove Distance in Patients With Patellar Instability

BACKGROUND

Tibial tubercle-trochlear groove (TT-TG) distance is a risk factor for recurrent patellar dislocation and is often included in algorithmic treatment of instability. The underlying factors that determine TT-TG have yet to be clearly described in orthopaedic literature.

PURPOSE/HYPOTHESIS

The purpose of our study was to determine the underlying anatomic factors contributing to TT-TG distance. We hypothesized that degree of tubercle lateralization and knee rotation angle may substantially predict TT-TG.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

All patients evaluated for patellar instability at a single institution between 2013 and 2021 were included. Patients with previous knee osseous procedures were excluded. TT-TG and its anatomic relationship to patellofemoral measures, including dysplasia, femoral anteversion, tibial tubercle lateralization, knee rotation angle, and tibial torsion, were measured and subsequently quantified using univariate and multivariable analysis.

RESULTS

In total, 76 patients met the inclusion criteria (46 female, 30 male; mean ± SD age, 20.6 ± 8.6 years) and were evaluated. Mean TT-TG was 16.2 ± 5.4 mm. On univariate analysis, increasing knee rotation angle (P < .01), tibial tubercle lateralization (P = .02), and tibial torsion (P = .01) were associated with increased TT-TG. In dysplastic cases, patients without medial hypoplasia (Dejour A or B) demonstrated significantly increased TT-TG (18.1 ± 5.4 mm) as compared with those with medial hypoplasia (Dejour C or D; TT-TG: 14.9 ± 5.2 mm; P = .02). Multivariable analysis revealed that increased knee rotation angle (+0.43-mm TT-TG per degree; P < .01) and tubercle lateralization (+0.19-mm TT-TG per percentage lateralization; P < .01) were statistically significant determinants of increased TT-TG distance. Upon accounting for these factors, tibial torsion, trochlear width, and medial hypoplasia were no longer significant components in predicting TT-TG (P≥ .54). Of note, all patients with TT-TG ≥20 mm had tibial tubercle lateralization ≥68%, a knee rotation angle ≥5.8°, or both factors concurrently.

CONCLUSION

TT-TG distance is most influenced by knee rotation angle and tibial tubercle lateralization.

Magnetic resonance imaging overestimates patellar height compared with radiographs

PURPOSE

To evaluate the inter-observer and inter-method reliability for patellar height measurements between conventional radiographs (CR) and magnetic resonance imaging (MRI) using one or two slices.

METHODS

This was a reliability study, with 60 patients divided in two groups: 30 patients with patellar instability (patella group) and 30 patients with anterior cruciate ligament or meniscus injury (control group). CR and MRI were evaluated by two independent observers. Insall-Salvati index (IS) and Caton-Deschamps index (CD) were measured using three different methods: CR, one-slice MRI or two-slice MRI. Intra-class correlation coefficients (ICC) were calculated for inter-observer reliability and inter-method reliability. Bland-Altman agreement was also calculated.

RESULTS

The inter-observer reliability was very good for the IS with ICCs of 0.93, 0.84 and 0.82, for the CR, one-slice MRI and two-slice MRI, respectively. Similarly, for the CD the ICCs were good, 0.76, 0.80 and 0.75 for the CR, one-slice MRI and two-slice MRI, respectively. No differences were found between the patella and the control group. The inter-method analysis results were: ICCs for IS (0.83, 0.86, 0.93) and CD (0.72, 0.82, 0.83), for the comparisons of CR/one-slice MR, CR/two-slice MRI and one-slice MRI/two-slice MRI, respectively. The Bland-Altman mean differences showed an 8% and a 7% increase on IS values with one-slice MRI and two-slice MRI compared to CR results, while the increase was of 9% and 1% in CD for the respective comparisons with CR.

CONCLUSION

MRI can overestimate patellar height compared to CR, as much as an 8% increase in Insall-Salvati values when using one- or two-slice MRI measurements, and up to a 9% increase in Caton-Deschamps value when using the one-slice MRI method. It is recommended to use the CR as the preferred method when measuring patellar height.

LEVEL OF EVIDENCE

III.

[Evaluation and diagnosis of knee joint diagonal lesion and surgical strategy and effectiveness]

Objective

To investigate the evaluation, diagnosis, and surgical treatment of knee joint diagonal lesion and to observe its effectiveness.

Methods

A retrospective analysis was performed on 9 patients with knee joint diagonal lesion admitted between November 2011 and November 2019, including 7 males and 2 females, aged 18-61 years, with an average age of 38.3 years. According to the clinical staging criteria of multiple ligament injury of knee joint, 6 patients with acute stage injury (≤3 weeks), the time from injury to operation was 5-16 days, with an average of 9.3 days; 3 patients with old stage injury (>3 weeks), the time from injury to operation was 7, 12, 144 months, respectively. Posterolateral complex injuries were all type C according to Fanelli classification, and the posterior cruciate ligament injury was grade 3 according to American Medical Association (AMA) classification. According to the three columns classification of tibial plateau fracture, there were 2 cases of zero column fracture and 7 cases of medial column fracture. Patients with acute injury were treated with posterior cruciate ligament reconstruction, posterolateral complex repair and/or reinforcement reconstruction, and tibial plateau fracture was treated with conservative treatment or internal fixation. Patients with malunion of tibial plateau in old stage were treated with limited osteotomy, bone grafting, and internal fixation; the stability of the knee joint was further evaluated during operation, then the posterior cruciate ligament reconstruction and/or posterolateral complex repair and reconstruction were performed as needed. Lysholm score and the International Knee Documentation Committee (IKDC) score before and after operation were used to evaluate knee function and effectiveness.

Results

All patients were followed up 24-119 months, with an average of 51.7 months. All the incisions healed by first intention, and no complication such as incision infection, deep venous thrombosis of lower extremities occurred, and there was no reoperation during follow-up. The full-length X-ray films of both lower extremities at 6 months and 1, 2 years after operation showed that the alignment of both lower extremities returned to normal, and the stress position X-ray films showed that the stability in all directions recovered well. The X-ray films of the knee joint at 6 months after operation showed that the fracture of the tibial plateau healed well. At 1 year after operation, MRI showed that the signal of the repaired and reconstructed ligament was good, and there was no reconstruction failure such as ligament absorption or rupture occurred. At 1 year after operation, the muscle strength of the affected limbs was all rated as grade Ⅴ, and the active and passive range of motion of the knee joint recovered to 0°-130°. At 2 years after operation, the Lysholm score and IKDC score significantly improved when compared with those before operation (P<0.05).

Conclusion

Knee joint diagonal lesion is a special type of posterior cruciate ligament and posterolateral complex injury with anteromedial split and collapse fracture of tibial plateau, which requires correct evaluation and diagnosis of the injured structure, and detailed surgical and rehabilitation programs to achieve better effectiveness.

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.

Morphological Analysis of Hip Joint of Patients Suffering From Recurrent Patella Dislocation

The purpose was to investigate morphological changes of the hip joint in patients with recurrent dislocation of the patella combined with trochlear dysplasia. There was a retrospective analysis of 148 patients and 150 control subjects. The selection of participants was randomized. Hip and knee data for all participants were obtained from X-ray or computed tomography measurements. Nine values, that is, central edge angle (CEA), acetabulum index angle (AIA), femoral neck-shaft angle, sharp angle, the depth of the acetabulum, femoral anteversion angle (FAA), anterior acetabular section angle (AASA), posterior acetabular section angle (PASA), and sulcus angle, were measured to evaluate differences between the control group and the patient group and analyze the correlation of the sulcus angle in patients to FAA and CEA. Patients with recurrent dislocation of the patella had less acetabular coverage and are more likely to develop developmental dysplasia of the hip than the hips of patients with normal knees. For the patient group, three values, that is, CEA (27.68 ± 5.25 vs. 34.30 ± 3.51 degrees, p < 0.001), AASA (57.14 ± 6.17 vs. 63.08 ± 7.23 degrees, p < 0.001), and PASA (89.53 ± 6.51 vs. 99.63 ± 5.94 degrees, p < 0.001), were decreased. The sharp angle (43.77 ± 3.23 vs. 39.28 ± 3.19 degrees, p < 0.001), AIA (11.52 ± 4.41 vs. 3.73 ± 2.51 degrees, p < 0.001), and FAA (24.68 ± 3.44 vs. 18.49 ± 3.55 degrees, p < 0.001) were increased. The acetabulum became shallower in-depth (7.05 ± 2.18 vs. 10.45 ± 1.61 mm, p < 0.001). There was a weak correlation between the sulcus angle and CEA (r =  - 0.302, p < 0.001) and FAA (r = 0.212, p = 0.022). Recurrent patellar dislocation combined with trochlear dysplasia may be associated with the hip morphology. Developmental disorders of the knee joint, and hip joint should be considered in the treatment of patients with recurrent dislocation of the patella.

Anatomical Risk Factors for Anterior Cruciate Ligament Injury Are Not Important As Patellar Instability Risk Factors in Patients with Acute Knee Injury

To compare in magnetic resonance imaging the anatomical risk factors for anterior cruciate ligament (ACL) injury and patellar dislocation among patients who suffered acute knee injury, 105 patients with acute knee injury resulting in 38 patellar dislocations (patella group), 35 ACL injuries (ACL group), and 32 meniscus or medial collateral ligament injuries (control group) were included. These groups were compared for risk factors for patellar dislocation (patellar height, trochlear dysplasia, and quadriceps angle of action) and for ACL injury (intercondylar width, posterior inclination of tibial plateaus, and depth of the medial plateau). Univariate analysis found statistically significant differences (p < 0.05) between the patella and ACL groups in patellar height (Caton-Deschamps [CD] 1.23 vs. 1.07), trochlear facet asymmetry (55 vs. 68%), PTTG (13.08 vs. 8.01 mm), and the patellar tip and trochlear groove (PTTG) angle (29.5 vs. 13.71 degrees). The patella group also differed from control in medial plateau inclination (4.8 vs. 1.87 degrees), patellar height (CD 1.23 vs 1.08), trochlear facet asymmetry (55 vs. 69%), lateral trochlear inclination (17.11 vs. 20.65 degrees), trochlear depth (4.1 vs. 6.05 mm), PTTG (13.08 vs. 9.85 mm), and the PTTG angle (29.5 vs. 17.88 degrees). The ACL and control groups were similar in all measures. Multivariate analysis found the following significant determinants between the Patella and Control groups: patellar height (CD index, odds ratio [OR]: 80.13, p = 0.015), trochlear anatomy (asymmetry of facets M/L, OR: 1.06, p = 0.031) and quadriceps action angle (PTTG angle, OR: 1.09, p = 0.016); between the ACL and control groups: PTTG angle (OR: 0.936, p = 0.04) and female gender (OR: 3.876, p = 0.032); and between the patella and ACL groups, the CD index (OR: 67.62, p = 0.026), asymmetry of the M/L facets (OR: 1.07, p = 0.011) and PTTG angle (OR: 1.16, p < 0.001). In conclusion, in patients with acute knee injury, the anatomical factors patellar height, trochlear dysplasia, and quadriceps angle of action were related to the occurrence of patellar dislocation. None of the anatomical factors studied was related to the occurrence of anterior cruciate ligament injury.

Surgical Correction of Non-traumatic Patella Maltracking. Midterm Clinical Follow-up

BACKGROUND

Patellar instability comprises a group of pathologies that allow the patella to move out of its trajectory within the trochlear groove during walking. Symptomatic patients who need surgery commonly undergo soft tissue procedures such as medial patellofemoral ligament repair to strengthen the ligaments that hold the patella in place. However, soft-tissue repairs may be insufficient in patients suffering from patellar maltracking, which is characterized by an unbalanced gliding of the patella within its route. In these patients, a different approach is advised. We aim to provide the mid-term clinical outcomes of the Fulkerson distal realignment operation in selected patients with non-traumatic patellar maltracking.

METHODS

The clinical outcomes of the Fulkerson distal realignment operation performed in 22 knees of 21 patients were evaluated by a self-administered subjective International Knee Documentation Committee (IKDC) score and the Tegner-Lysholm knee scoring scale.

RESULTS

Before surgery, the median IKDC score was 52, and the median Tegner-Lysholm score was 56. Following surgery (mean follow-up 48 months, range 24-156), the median IKDC and the Tegner-Lysholm scores were 67 and 88, respectively. The improvement was statistically significant (P=0.001 and P=0.002 for IKDC and Tegner-Lysholm scores, respectively). Associated procedures included patella microfracture due to grade III-IV cartilage lesion (International Cartilage Repair Society grading system) in four patients, retinacular releases in three patients, medial capsular augmentations in two patients, and medial patellofemoral ligament reconstruction in two patients. One patient with Ehlers-Danlos disease required excessive medialization of the tibial tuberosity. Surgery-related complications occurred in three patients.

DISCUSSION

Surgical correction of patellar maltracking with Fulkerson distal realignment combined with associated procedures in individual patients was associated with an increase in subjective and functional clinical scores at medium-term follow-up. Particular attention should address pathologies associated with patellar maltracking and managed accordingly.

LEVEL OF EVIDENCE

4c (case series).

Multi-Stage Platform for (Semi-)Automatic Planning in Reconstructive Orthopedic Surgery

Intricate lesions of the musculoskeletal system require reconstructive orthopedic surgery to restore the correct biomechanics. Careful pre-operative planning of the surgical steps on 2D image data is an essential tool to increase the precision and safety of these operations. However, the plan’s effectiveness in the intra-operative workflow is challenged by unpredictable patient and device positioning and complex registration protocols. Here, we develop and analyze a multi-stage algorithm that combines deep learning-based anatomical feature detection and geometric post-processing to enable accurate pre- and intra-operative surgery planning on 2D X-ray images. The algorithm allows granular control over each element of the planning geometry, enabling real-time adjustments directly in the operating room (OR). In the method evaluation of three ligament reconstruction tasks effect on the knee joint, we found high spatial precision in drilling point localization (ε<2.9mm) and low angulation errors for k-wire instrumentation (ε<0.75∘) on 38 diagnostic radiographs. Comparable precision was demonstrated in 15 complex intra-operative trauma cases suffering from strong implant overlap and multi-anatomy exposure. Furthermore, we found that the diverse feature detection tasks can be efficiently solved with a multi-task network topology, improving precision over the single-task case. Our platform will help overcome the limitations of current clinical practice and foster surgical plan generation and adjustment directly in the OR, ultimately motivating the development of novel 2D planning guidelines.

Tape Augmentation Does Not Affect Mid-Term Outcomes of Medial Patellofemoral Ligament Reconstruction in Skeletally Mature Adolescent Patients

Purpose

To evaluate mid-term outcomes after medial patellofemoral ligament (MPFL) reconstruction with and without tape augmentation in the skeletally mature adolescent population.

Methods

All patients under age 18 with recurrent patellar instability treated with surgery at a single institution by a single surgeon from January 2013 through June 2017 were identified by current procedural terminology codes. Inclusion criteria were (1) primary MPFL reconstruction, (2) minimum 3 years’ follow-up, (3) skeletal maturity. Exclusion criteria were (1) bilateral MPFL reconstruction using different techniques on each knee, (2) prior surgery for patellar instability. Chart and imaging review was completed. Patients were contacted to complete a questionnaire, which included the International Knee Documentation Committee (IKDC) form.

Results

Fifty-one of 92 eligible patients completed questionnaires. Two patients were excluded. Twenty patients underwent 23 non-augmented MPFL reconstructions; 29 patients underwent 33 augmented MPFL reconstructions. Group demographics were similar. At 4.9 ± 1.2 years follow-up, mean IKDC scores were 77.4 and 79.4 in the nonaugmentation and augmentation groups, respectively. Significantly fewer patients in the augmentation group experienced further injury to their ipsilateral knee compared to the non-augmentation group (6% vs 30%, P = .019). Fewer knees in the augmentation group developed recurrent subjective instability or dislocation after initial surgery requiring surgical correction compared to knees in the nonaugmentation group, although this difference was not significant (6% vs 17%, P = 0.181). Overall patient-reported outcomes were similar between the 2 groups.

Conclusions

There were no significant differences in patient-reported outcomes after MPFL reconstruction with or without tape augmentation. Tape augmentation significantly decreased the risk of subsequent ipsilateral knee injuries, although it did not show a significant difference in recurrent dislocations.

Level of Evidence

IV, therapeutic case series.

Effect of Isolated Medial Patellofemoral Ligament Reconstruction in Patellofemoral Instability Regardless of Predisposing Factors

The purpose of this study was to evaluate the outcomes of isolated medial patellofemoral ligament (MPFL) reconstruction, regardless of the presence of predisposing factors. A total of 21 knees that underwent isolated MPFL reconstruction from March 2014 to August 2017 were included in this retrospective series. Radiographs of the series of the knee at flexion angles of 20, 40, and 60 degrees were acquired. The patellar position was evaluated using the patellar tilt angle, sulcus angle, congruence angle (CA), and Caton-Deschamps and Blackburne-Peel ratios. To evaluate the clinical outcome, the preoperative and postoperative International Knee Documentation Committee (IKDC) and Lysholm knee scoring scales were analyzed. To evaluate the postoperative outcomes based on the predisposing factors, the results were separately analyzed for each group. Regarding radiologic outcomes, 20-degree CA was significantly reduced from 10.37 ± 5.96° preoperatively to -0.94 ± 4.11° postoperatively (p = 0.001). In addition, regardless of the predisposing factors, delta values of pre- and postoperation of 20-degree CA were not significantly different in both groups. The IKDC score improved from 53.71 (range: 18-74) preoperatively to 94.71 (range: 86-100) at the last follow-up (p = 0.004), and the Lysholm score improved from 54.28 (range: 10-81) preoperatively to 94.14 (range: 86-100) at the last follow-up (p = 0.010). Isolated MPFL reconstruction provides a safe and effective treatment for patellofemoral instability, even in the presence of mild predisposing factors, such as trochlear dysplasia, increased patella height, increased TT-TG distance, or valgus alignment. This is a Level 4, case series study.

Are Patellofemoral Ligaments and Retinacula Distinct Structures of the Knee Joint? An Anatomic, Histological and Magnetic Resonance Imaging Study

There is disagreement regarding the description of the patellofemoral ligaments (PFLs), considered by some authors as capsular thickening and by others as independent ligaments. It was hypothesised that the PFLs and retinacula are structures with different histological features. The aim of this study was to describe the stabilising structures of the patella in detail and to determine if the PFLs and retinacula are different and separable structures from a macroscopic, microscopic and imaging viewpoint. An anatomical study was performed on eight knees from five cadavers (mean age, 56.2 years; range, 35–63 years), and a histological study was conducted on specimens from nine patients having a mean age of 65 years (range 35–84 years) who had undergone surgical knee procedures. The imaging study was based on 100 MRIs (96 patients). The mean age was 46 years (range 16–88), and the study analysed the capsular-ligamentous structures. In the medial compartment, the layers and structures were as follows: superficial layer, medial retinaculum; intermediate layer, Medial Collateral Ligament (MCL), Posterior Oblique Ligament (POL) and Medial Patellofemoral Ligament (MPFL); deep layer, deep part of the MCL and joint capsule. In the lateral compartment, the layers and structures were the following: superficial layer, lateral retinaculum; intermediate layer, Lateral Collateral Ligament (LCL) and Lateral Patellofemoral Ligament (LPFL); deep layer, joint capsule. All of the knees examined presented a clearly distinguishable MPFL and LPFL separable from the capsular layer. Histological study: there was a higher density of nerve fibres in retinacula compared to ligaments (p = 0.0034) and a higher content of elastic fibres in retinacula (p < 0.0005). In imaging, there was no difference between medial and lateral retinaculum thickness (p > 0.05). In conclusion, both the lateral and medial compartment can be described using the three-layer scheme. PFLs and retinacula are separate structures both macroscopically and according to imaging analysis. The retinacula respond to their specific function with a higher nerve fibre content and higher number of elastic fibres compared to the ligaments.

Chondral and Soft Tissue Injuries Associated to Acute Patellar Dislocation: A Systematic Review

INTRODUCTION

Chondral and soft tissue injuries can be associated with first time patellar dislocation, but it is unclear how common they are, and which tissues are affected. A systematic review of the literature was performed to investigate the frequency, location, and extent of chondral and medial patellofemoral ligament (MPFL) injuries in patients following first time patellar dislocation.

METHODS

This systematic review was conducted according to the PRISMA guidelines. PubMed, Google Scholar, Embase, and Web of Science databases were accessed in November 2021. All the published clinical studies reporting the frequency, location, and extent of soft tissue lesions following first time patellar dislocation were accessed. Studies reporting data on habitual, congenital, or recurrent patellofemoral instability were excluded.

RESULTS

Data from 42 articles (2254 patients, mean age 21.6 ± 7.3 years) were retrieved. Ninety-eight percent of patients who experienced first time patellar dislocation demonstrated MPFL rupture at MRI. Forty-eight percent of MPFL ruptures were located at the patellar side, 34% at the femoral insertion site, and 18% in the midportion. Eighty-five percent of patients showed signs of patellar chondral damage at MRI, and trochlear chondral injuries were evidenced in 47% of patients. Intra-articular loose bodies were observed in 11.5% of patients. At arthroscopy, the medial facet and the crest of the patella more commonly exhibited chondral lesions than the lateral facet and femoral trochlea.

CONCLUSIONS

Most patients suffer chondral damage and MPFL tears following after a first time patellar dislocation.

Older, Heavier, Arthritic, Psychiatrically Disordered, and Opioid-Familiar Patients Are at Risk for Opioid Use After Medial Patellofemoral Ligament Reconstruction

Purpose

To investigate which factors predispose patients for prolonged opioid use after medial patellofemoral ligament (MPFL) reconstruction.

Methods

A retrospective review of all patients who underwent MPFL reconstruction at a single institution between January 2013 and June 2020 was conducted. Opioid consumption before and after surgery was recorded and confirmed using Michigan Automated Prescriptions System monitoring program. Patients were classified into preoperative opioid users and nonusers. Risk factors for continued opioid use were assessed by collecting patient demographic variables, psychiatric history, number of previous patellar dislocations, and operative factors.

Results

A total of 102 patients were included during the time frame of interest. Patients were on average 21.6 ± 8.5 years old with a mean body mass index of 28.2 ± 7.9. Thirty patients (29.0%) sustained >10 dislocations preoperatively. Preoperative opioid use was present in 13 (12.7%) patients. Greater than 10 dislocations (odds ratio [OR] 5.00, 95% confidence interval [CI] 1.12-20.92) and psychiatric history (OR 3.33, 95% CI, 1.2-9.1; P = .016) significantly predicted opioid refills the first month after surgery. Risk factors for opioid refills at 2 to 12 months postoperatively included smoking (OR 4.50, 95% CI 1.13-17.96), preoperative opioid use (OR 7.32, 95% CI 1.88-28.47), psychiatric disorder (OR 3.77, 95% CI 2.3-6.2; P < .001), age >30 years (OR 7.03, 95% CI 3.63-13.61; P < .001), and obesity (OR 2.68, 95% CI 1.40-5.14; P = .002). Compared with Outerbridge 0, a greater percentage of patients with Outerbridge 1 or 2 and 3 or 4 continued using opioids 2 to 12 months after surgery (OR 3.06, 95% CI 1.33-7.02; P = .006 and OR 2.86, 95% CI 1.24-6.59; P = .010, respectively).

Conclusions

For patients undergoing MPFL reconstruction, preoperative opioid use, cartilage damage, age >30 years, smoking history, body mass index >30, and history of psychiatric disorder were found to be significantly associated with prolonged opioid use after surgery. Postoperative opioid refills in this cohort declined after 1 month.

Level of Evidence

Level III, retrospective cohort study.

Current practice trends in the surgical management of patellofemoral instability: a survey of the Paediatric Research in Sports Medicine (PRiSM) Society

PURPOSE

Patellofemoral instability (PFI) in young athletes presents both diagnostic and management dilemmas for which consensus often does not exist. The purpose of this study was to identify trends in management of PFI in children and adolescents in the United States and nationwide.

METHODS

A 27-question multiple choice survey was distributed in 2018 to the members of the Pediatric Research in Sports Medicine (PRiSM) Society regarding treatment of PFI in paediatric and adolescent patients.

RESULTS

In all, 56 of the respondents who were orthopaedic surgeons that manage patellar instability in children and adolescents and had performed PFI surgery more than five times in the past year completed the entire survey. A total of 41% of respondents reported that surgery for fragment refixation or loose body removal was indicated when a loose body or osteochondral fragment was evident, regardless of fragment size. Overall, 74% reported that if surgery was performed for an osteochondral loose body, primary repair (36%) or reconstruction (38%) of medial patellofemoral ligament (MPFL) was also completed. A total of 89% of members reported MPFL reconstruction in the absence of alignment or rotational abnormalities, tibial tubercle lateralization or trochlear dysplasia in skeletally immature patients; 59% reported performing the MPFL reconstruction with hamstring allograft, while 30% prefer autograft (hamstring, quadriceps). For patients with significant trochlear dysplasia, 87% reported no surgical management of trochlea in first-time or in revision surgery.

CONCLUSION

There is a lack of consensus regarding optimal diagnostic and treatment algorithms in the management of PFI, however, consistent trends have emerged among paediatric sports medicine surgeons.

LEVEL OF EVIDENCE

Level V - survey of expert opinion and experience.

Medial Patellofemoral Ligament Reconstruction Techniques and Outcomes: a Scoping Review

PURPOSE OF REVIEW

The purpose of this scoping literature review was to summarize the current evidence on techniques and outcomes following MPFL reconstruction including sources of evidence, key concepts, and gaps in the literature.

RECENT FINDINGS

A thorough electronic database search included studies published from 2016 to April 26, 2021, identified a total of 144 peer reviewed articles. Of the 144 identified clinical papers, 80 (56%) were of level IV evidence, 49 (34%) were of level III evidence, 11 (8%) were level II evidence, and 4 (3%) were level I evidence. Overall, 10,710 patients (11,466 knees) were included with 6871 (64%) female. The mean age of patients included in these studies was 23.5 years (range=5 to 59). In recent years, there has been a substantial quantity of evidence published on MPFL reconstruction from a variety of different countries and journals and of variable methodological design. Isolated MPFL reconstruction results in a decrease in patellar height postoperatively. Indications for isolated MPFL reconstruction versus concomitant procedures to address bony morphology is still incompletely defined. When failure does occur after MPFL reconstruction, femoral tunnel malposition is the most commonly cited cause. Despite several recent studies focused on optimal MPFL reconstruction techniques, there is currently no consensus on optimal graft type (most common being hamstring autografts, allografts, and recently synthetic grafts) or femoral fixation strategies, with similar results reported with each technique. Future studies should focus on optimal techniques for each patient population as well as specific indications for additional concomitant realignment procedures.

Clinical outcomes and predictive factors for failure with MPFL reconstruction combined with tibial tubercle osteotomy and lateral retinacular release for recurrent patellar instability

BACKGROUND

Medial patellofemoral ligament (MPFL) reconstruction combined with tibial tubercle osteotomy (TTO) and lateral retinacular release (LRR) is one of the main treatment methods for patellar instability. So far, few studies have evaluated the clinical effectiveness and assessed potential risk factors for recurrent patellar instability.

PURPOSE

To report the clinical outcomes of MPFL reconstruction combined with TTO and LRR at least three years after operation and to identify potential risk factors for recurrent patellar instability.

METHODS

A retrospective analysis of medical records for patients treated with MPFL, TTO and LRR from 2013 to 2017 was performed. Preoperative assessment for imaging examination included trochlear dysplasia according to Dejour classification, patella alta with the Caton-Deschamps index (CDI), tibial tubercle-trochlear groove distance. Postoperative assessment for knee function included Kujala, IKDC and Tegner scores. Failure rate which was defined by a postoperative dislocation was also reported.

RESULTS

A total of 108 knees in 98 patients were included in the study. The mean age at operation was 19.2 ± 6.1 years (range, 13-40 years), and the mean follow-up was 61.3 ± 15.4 months (range, 36-92 months). All patients included had trochlear dysplasia (A, 24%; B, 17%; C, 35%; D, 24%), and 67% had patellar alta. The mean postoperative scores of Tegner, Kujala and IKDC were 5.3 ± 1.3 (2-8), 90.5 ± 15.5 (24-100) and 72.7 ± 12.1 (26-86). Postoperative dislocation happened in 6 patients (5.6%). Female gender was a risk factor for lower IKDC (70.7 vs 78.1, P = 0.006), Tegner (5.1 vs 6.0, P = 0.006) and Kujala (88.2 vs 96.6, P = 0.008). Age (p = 0.011) and trochlear dysplasia (p = 0.016) were considered to be two failure factors for MPFL combined with TTO and LRR.

CONCLUSION

As a surgical method, MPFL combined with TTO and LRR would be a reliable choice with a low failure rate (5.6%). Female gender was a risk factor for worse postoperative outcomes. Preoperative failure risk factors in this study were age and trochlear dysplasia.

LEVEL OF EVIDENCE

Level IV; Case series.

Anterior and distal tunnel orientation for anatomic reconstruction of the medial patellofemoral ligament is safer in patients with open growth plates

PURPOSE

In patients with open growth plates, the direction of tunneling that avoids distal femoral physis (DFP) damage in anatomic reconstructions of the medial patellofemoral ligament (MPFL) has been a topic of discussion. The objective of this study was to determine the ideal orientation for anatomic reconstructions of MPFL tunneling that minimized DFP damage while avoiding breaching the intercondylar notch.

METHODS

Eighty magnetic resonance images of patients aged 10 through 17 were obtained, randomly sampled from the institutional database. A de novo software was developed to obtain 3D models of the distal femur and DFP. In each model, the anatomical insertion point of the MPFL was determined as defined by Stephen. A 20-mm-depth drilling was simulated, starting from the insertion point at every possible angle within a 90° cone using 5-, 6- and 7-mm drills. Physeal damage for each pair of angles and each drill size was determined. Damage was expressed as a percentage of total physis volume. Statistical analysis was conducted using Student's t test and one-way ANOVA.

RESULTS

Maximum physeal damage (5.35% [4.47-6.24]) was obtained with the 7-mm drill when drilling 3° cephalic and 15° posterior from insertion without differences between sexes (n.s.). Minimal physeal damage (0.22% [0.07-0.37]) was obtained using the 5-mm drill aimed 45° distal and 0° anteroposterior, not affected by sex (n.s.). Considering intra-articular drilling avoidance, the safest zone was obtained when aiming 30°-40° distal and 5°-35° anterior, regardless of sex.

CONCLUSION

Ideal femoral tunnel orientation, avoiding physeal damage and breaching of the intercondylar notch, was obtained when aiming 30°-40° distal and 5°-35° anterior, regardless of sex. This area is a safe zone that allows anatomic MPFL reconstruction of patients with an open physis.

Decreasing Thickness of Partial Lateral Trochlear Cartilage in Patients with Patellar Instability

Objective

To explore morphological characteristics of patellofemoral joint surface of patients with patellar instability by adopting the MRI‐based method.

Methods

A retrospective analysis was performed from March 2016 to January 2020 to assess morphological characteristics of the patellofemoral joint surface by Magnetic Resonance Imaging (MRI) scanning knees of 30 patients (24 females, six males) with patellar instability and trochlear dysplasia and knees of 30 subjects from a randomly selected control group (25 females, five males). The control group was matched as per age and sex. All participants had undergone MRI scans in the supine position and keep knees in or near full extension. Six parts were measured in total, including thickness of trochlear cartilage, thickness of patella cartilage, cartilaginous sulcus angle, cartilaginous Wiberg angle, contact range and frequency and distributions of the mean difference measurement of the femoral trochlea, to evaluate the difference of trochlear and patellar morphology between the patient group and the control group. The threshold for statistical significance was set at P < 0.05.

Results

There were significant differences in four values between the two groups (P < 0.05). The cartilage thickness two‐third along the lateral condyle in the patient group was significantly lower than that in the control group (LCT2,1.80 ± 0.37 vs 2.06 ± 0.52, 1.92 ± 0.36 vs 2.17 ± 0.50), but there was no significant difference in other sites. There was no significant difference in patella thickness between the patient group and the control group. The cartilaginous sulcus angle in the patient group was larger than that in the control group (157.90 ± 6.64 vs 142.23 ± 3.95, P < 0.001), but there was no significant difference in cartilaginous Wiberg angle. The patient group had a larger initial contact ratio (59.47 ± 6.13 vs 46.50 ± 3.67, P < 0.001), and a smaller contact range (16.55 ± 4.14 vs 27.55 ± 4.09, P < 0.001). The deepest part of the intercondylar suclus appears more often in the lateral of the deepest part of the osseous concavity of the femoral trochlea. Among the patient group, 18 cases (60%) were found with the deepest part of the intercondylar suclus lateral to the deepest point of the osseous concavity of the femoral trochlea while among the control group only 4 cases (13.33%) were found. The distribution of trochlear dysplasia of Dejour grades was type B (n = 22), type C (n = 5), and type D (n = 3).

Conclusion

Thickness of partial lateral trochlear cartilage decreases in patients with patellar instability and the trochlear cartilage develops abnormal morphological characteristics. Moreover, it also suggests that MRI can be used to further present the morphology of cartilage for the convenience of surgical planning.

Current Concepts Regarding Patellofemoral Trochlear Dysplasia

Optimal treatment of patients with patellofemoral trochlear dysplasia and recurrent patellar instability requires in-depth understanding of this complex structural anomaly. An extensive review of the literature suggests that dysplasia occurs as a result of aberrant forces applied to the patellofemoral joint in the majority of cases. Evidence supports surgical stabilization that reconstructs the medial patellofemoral and/or medial quadriceps tendon-femoral ligament without added trochleoplasty in the majority of patients with trochlear dysplasia and recurrent patellar instability. Adding tibial tubercle transfer distally, medially, or anteromedially in those who need it to treat specific deficits in alignment or articular cartilage can be beneficial in selected patients with trochlear dysplasia and recurrent patellar instability. Trochleoplasty may be appropriate in those few cases in which permanent stable patellofemoral tracking cannot be restored otherwise, but the indications are not yet clear, particularly as trochleoplasty adds risk to the articular cartilage. Improved understanding of imaging techniques and 3-dimensional reproductions of dysplastic patellofemoral joints are useful in surgical planning for patients with recurrent patellar instability and trochlear dysplasia.

Linear influence of distal femur osteotomy on the Q-angle: one degree of varization alters the Q-angle by one degree

PURPOSE

The effect of a distal femur varization osteotomy on patellofemoral biomechanics in genu valgum is unknown. The purpose of this study was to quantify the influence of frontal leg axis correction on the Q-angle with a novel three-dimensional (3-D) measurement method.

METHODS

3-D surface models of ten lower extremities were generated using patient computed tomography (CT) data. The preoperative 3-D Q-angle was measured using a novel defined and validated 3-D measurement method. Biplanar supracondylar osteotomies were simulated with different degrees of varus correction (from 1° to 15°) in one-degree steps beginning from the preoperative valgus deformity, resulting in a total of 150 simulations. Additionally, mechanical leg axis and 3-D Q-angle measurements were performed on 3-D surface models of the postoperative CT scans of the same individuals. Further, pre- and postoperative TT-TG distance was measured.

RESULTS

Mean preoperative Q-angle was 15.8 ± 3.9° (range 10°-21.4°) with a mean preoperative mechanical leg axis of 6.5° ± 2.4 valgus (range 3.8°-11.6° valgus). The Q-angle changed linearly 0.9 ± 0° per 1° of varization. No difference was detected between simulated 3-D Q-angles and effectively corrected postoperative values (n.s.). TT-TG distance changed irregularly and minimally, and with no correlation to the degree of varization.

CONCLUSION

Distal femur varization osteotomy has a linear effect on the Q-angle with a change of 1° per 1° of varization. The difference in TT-TG distance was mainly due to an unintentional rotational component implemented during surgery.

Tibial Tubercle Osteotomy With Distalization Is a Safe and Effective Procedure for Patients With Patella Alta and Patellar Instability

Background:

Tibial tubercle osteotomy with concomitant distalization for the treatment of patellar instability remains controversial, as it may cause anterior knee pain and chondral degeneration.

Purpose:

To evaluate radiographic, clinical, and functional outcomes in patients who had patellar instability with patella alta and underwent tibial tubercle osteotomy with distalization (TTO-d) as well as medial patellofemoral ligament reconstruction.

Study Design:

Case series; Level of evidence, 4.

Methods:

Included in this study were 25 patients (31 cases) (mean age at surgery, 28.7 years; range, 14-33 years) with patellar instability and patella alta who underwent TTO-d with minimum 1-year follow-up. The Caton-Deschamps index (CDI), tibial tubercle–trochlear groove (TT-TG) distance, and amount of distalization were assessed. Clinical and functional variables included J-sign, anterior knee pain, apprehension test, Tegner activity level, and Kujala score.

Results:

The mean follow-up period was 2.62 years. The mean TT-TG was 16.15 mm (range, 7-24 mm); the mean CDI changed from 1.37 (1.25-1.7) preoperatively to 1.02 (0.9-1.12) postoperatively (P = .001); and the mean amount of tibial tubercle distalization was 8.80 mm (range, 4-16 mm). Lateral release (22 cases; 71.0%), medialization of tibial tubercle (17 cases; 54.8%), and autologous chondrocyte implantation (4 cases; 12.9%) were other associated procedures. The J-sign improved in 30 cases (96.8%; P = .001), and there was a complete resolution of anterior knee pain in 22 cases (71.0%; P = .001). An exploratory analysis showed that patellar cartilage defect severity was correlated with persistent pain (P = .005). The apprehension test became negative in all cases (P = .001). The median Kujala score increased from 52 to 77 (P = .001), and the median Tegner activity level improved from 3 to 4 (P = .001). No cases of osteotomy nonunion were reported. One case (3.2%) of patellar instability recurrence and 3 cases (6.5%) with painful hardware were observed.

Conclusion:

TTO-d resulted in good radiographic, clinical, and functional outcomes providing proper patellar stability to patients with patella alta. TTO-d appears to be a safe and efficient procedure with low complication rates, providing an additional tool for the personalized treatment of patellar instability.

Assessment and Trends of the Methodological Quality of the Top 50 Most Cited Articles on Patellar Instability

BACKGROUND

Studies with a low level of evidence (LOE) have dominated the top cited research in many areas of orthopaedics. The wide range of treatment options for patellar instability necessitates an investigation to determine the types of studies that drive clinical practice.

PURPOSE

To determine (1) the top 50 most cited articles on patellar instability and (2) the correlation between the number of citations and LOE or methodological quality.

STUDY DESIGN

Cross-sectional study.

METHODS

The Scopus and Web of Science databases were assessed to determine the top 50 most cited articles on patellar instability between 1985 and 2019. Bibliographic information, number of citations, and LOE were collected. Methodological quality was calculated using the Modified Coleman Methodology Score (MCMS) and the Methodological Index for Non-Randomized Studies (MINORS). Mean citations and mean citation density (citations per year) were correlated with LOE, MCMS, and MINORS scores.

RESULTS

Most studies were cadaveric (n = 10; 20.0%), published in the American Journal of Sports Medicine (n = 13; 26.0%), published between 2000 and 2009 (n = 41; 82.0%), and conducted in the United States (n = 17; 34.0%). The mean number of citations and the citation density were 158.61 ± 59.53 (range, 95.5-400.5) and 12.74 ± 5.12, respectively. The mean MCMS and MINORS scores were 59.62 ± 12.58 and 16.24 ± 3.72, respectively. No correlation was seen between mean number of citations or citation density versus LOE. A significant difference was found in the mean LOE of articles published between 1990 and 1999 (5.0 ± 0) versus those published between 2000 and 2009 (3.12 ± 1.38; P = .03) and between 2010 and 2019 (3.00 ± 1.10; P = .01).

CONCLUSION

There was a shift in research from anatomy toward outcomes in patellar instability; however, these articles demonstrated low LOE and methodological quality. Higher quality studies are necessary to establish informed standards of management of patellar instability.

Good outcomes of modified Grammont and Langenskiöld technique in children with habitual patellar dislocation

PURPOSE

In this study, the functional mid-term outcomes of the modified Grammont and Langenskiöld technique was assessed in skeletally immature patients with habitual patellar dislocation, with emphasis on knee function, pain, and other possible post-surgical complications. This is the first study concerning the application of the modified Grammont and Langenskiöld technique in habitual patellar dislocations.

METHODS

This retrospective cohort study considered 10 patients (15 knees), ranging from 7 to 11 years old, who underwent the modified Grammont and Langenskiold procedure between 2015 and 2018. History of dislocation, patellar stability and range of motion (ROM) were analysed. To assess functional improvement and knee pain, the Kujala Anterior Knee Pain Scale and KOOS-Child Knee Survey were used before and after surgical treatment.

RESULTS

No history of dislocation was noted after surgical treatment. All 15 knees showed full ROM. There were no signs of genu recurvatum and no length discrepancies were found. The subjective assessment revealed significant improvement in the scores of the KOOS-Child questionnaire in all five sections (p < 0.001), as well as in The Kujala Anterior Knee Pain Scale (p = 0.001).

CONCLUSION

The modified Grammont and Langenskiöld technique yields remarkable results in terms of knee stability and knee function, while decreasing recurrence risk and intensity of pain in patients with challenging cases of patellofemoral joint dislocation. This surgical technique is most effective in cases where the patella remains dislocated continuously; however, it may also be used in immature patients with recurrent instability.

LEVEL OF EVIDENCE

IV.

Comparison of Ligament Isometry and Patellofemoral Contact Pressures for Medial Patellofemoral Ligament Reconstruction Techniques in Skeletally Immature Patients

BACKGROUND

Adult medial patellofemoral ligament (MPFL) reconstruction techniques are not appropriate for the skeletally immature patient given the proximity of the distal femoral physis. Biomechanical consequences of reconstructions aimed at avoiding the physis have not been adequately studied.

PURPOSE

To quantify the biomechanical effects of MPFL reconstruction techniques intended for skeletally immature patients.

STUDY DESIGN

Controlled laboratory study.

METHODS

Four MPFL reconstruction techniques were evaluated using a computationally augmented cadaveric model: (1) Schoettle point: adult-type reconstruction; (2) epiphyseal: socket distal to the femoral physis; (3) adductor sling: graft wrapped around the adductor tendon; (4) adductor transfer: adductor tendon transferred to patella. A custom testing frame was used to cycle 8 knees for each technique from 10° to 110° of flexion. Patellofemoral kinematics were recorded using a motion camera system, contact stresses were recorded using Tekscan pressure sensors, and MPFL length was computed using an inverse kinematics computational model. Change in MPFL length, patellar facet forces, and patellar kinematics were compared using generalized estimating equation modeling.

RESULTS

Schoettle point reconstruction was the most isometric, demonstrating isometry from 10° to 100°. The epiphyseal technique was isometric until 60°, after which the graft loosened with increasing flexion. The adductor sling and adductor transfer techniques were significantly more anisometric from 40° to 110°. Both grafts tightened with knee flexion and resulted in significantly more lateral patellar tilt versus the intact state in early flexion and significantly higher contact forces on the medial facet versus the epiphyseal technique in late flexion.

CONCLUSION

In this cadaveric simulation, the epiphyseal technique allowed for a more isometric ligament until midflexion, when the patella engaged within the trochlear groove. The adductor sling and adductor transfer grafts became tighter in flexion, resulting in potential loss of motion, pain, graft stretching, and failure. Marginal between-condition differences in patellofemoral contact mechanics and patellar kinematics were observed in late flexion.

CLINICAL RELEVANCE

In the skeletally immature patient, using an epiphyseal type MPFL reconstruction with the femoral attachment site distal to the physis results in a more isometric graft compared with techniques with attachment sites proximal to the physis.

Update on Patellar Instability

Patellar instability is a multifactorial clinical condition that affects a significant number of patients and occurs due to morphological variations of the joint and patellofemoral alignment. The present literature review study aimed to identify and summarize current concepts on patellar instability, in relation to associated risk factors, diagnostic criteria, and the benefits and risks of conservative and surgical treatments. For this purpose, a search was conducted in the following electronic databases: MEDLINE (via Pubmed), LILACS and Cochrane Library. It is concluded that the accurate diagnosis depends on the detailed clinical evaluation, including the history and possible individual risk factors, as well as imaging exams. The initial treatment of patellar instability is still controversial, and requires the combination of conservative and surgical interventions, taking into consideration both soft tissues and bone structures, the latter being the most common reason for choosing surgical treatment, especially lateral patellar instability.

Anatomy and biomechanics of the medial patellotibial ligament: A systematic review

BACKGROUND

The knowledge of the anatomy and biomechanics of patellar stabilizers is mandatory to achieve good clinical results with surgical reconstructive procedures. Few articles provide clear anatomical and biomechanical picture of medial patello-tibial ligament (MPTL).

METHODS

After a systematic review of the literature we selected in vivo or ex vivo studies providing anatomical or biomechanical measurements. We included 7 studies about MPTL anatomy for a total of 96 knees and 4 biomechanical studies.

RESULTS

The MPTL is a true ligament and important component of the medial patellar stabilizers, together with the medial patello-femoral ligament (MPFL) and medial patello-meniscal ligament. The contribution of MPTL on restriction forces of the patello-femoral joint is still unclear. Quadriceps, patellar, semitendinous and gracilis tendons are adequate grafts for surgical MPTL reconstruction.

CONCLUSIONS

MPTL is a well defined anathomical structure and histologically can be considered a ligament. It plays an important role in patellar stability especially it has a main role on patellar rotation and tilt instead on shift.

Isolated Medial Patellofemoral Ligament Reconstruction Can Be an Effective Procedure in Patellofemoral Instability with Risk Factors

Patellofemoral instability is a severe problem in young and active patients. This pathology is influenced by ligamentous, bony, and neuromuscular parameters. The reconstruction of the medial patellofemoral ligament (MPFL) evolved to a primary procedure, but combined procedures were more frequently performed in the past years. However, additional operative procedures are associated with increased morbidity and no absolute indication can be identified in the literature. This study is intended to clarify whether addressing only ligamentous influence factors (MPFL) in chronic patellofemoral instability is sufficient to produce good clinical outcomes, or whether other risk factors influence the results negatively and should also be treated at some point. In 52 patients with chronic patellofemoral instability patellar height according to Caton-Deschamps, trochlear dysplasia according to Dejour, the leg axis, the femoral antetorsion, tibial tubercle (TT)-trochlear groove, and TT-posterior cruciate ligament distance were evaluated. All patients were treated with isolated MPFL reconstruction. After a minimum follow-up period of 24 months (24-36 months), the clinical outcome results were calculated using the scoring system according to Lysholm and Tegner. Correlation between clinical outcome scores and anatomic risk factors were calculated. The analysis was performed using a standard statistical software package (JMP version 12, SAS Institute, Cary, NC). The average postoperative Lysholm score increased significantly from 57.23 ± 19.9 to 85.9 ± 17.2 points (p < 0.0001) after isolated MPFL reconstruction. Moreover, the Tegner and Lysholm scores significantly improved both in patients without and with different risk factors postoperative. There were no significant differences in the outcome sores between the groups. Even the degree of trochlear dysplasia (types I-III) did not influence the results. Finally, there was no significant correlation found between all collected risk factors and the postoperative outcome scores. Isolated MPFL reconstruction can be an effective procedure in patients with patellofemoral instability and mild to moderate risk factors.

Traumatic Patellar Dislocations in Childhood and Adolescents

Patellar instability and associated patellar dislocation can result in significant pain, disability, and associated injuries in young athletes. The patellofemoral joint is a complex articulation with stabilizing restraints, both medially and laterally, that help guide the patella into the corresponding trochlear groove as the knee cycles through an extension-to-flexion arc. In addition to soft tissue injuries, many osseous aberrancies can contribute to patellar instability in young athletes, including trochlear dysplasia, patella alta, and axial and coronal plane abnormalities. There is a role for nonoperative treatment in these young athletes; however, if recurrent or associated injuries are identified surgical intervention is warranted. Correct diagnosis of the underlying cause of the patellar instability is paramount to developing a surgical plan that will yield the most favorable outcome for these young athletes.

Initial conservative treatment of osteochondral fracture of the patella following first-time patellar dislocation

Background

There has been no gold standard of the initial treatment strategy for acute patellar dislocation (APD) with osteochondral fracture (OCF). Hence the study aim is firstly, to review and compare clinical outcomes of patients who underwent conservative treatment for APD with or without OCF. Secondly, to characterize the location and size of fracture fragment.

Methods

Sixty-nine consecutive patients who were retrospectively evaluated after first-time APD over a 2- year period were divided into two groups (group 1 (n = 24): APD with OCF and group 2 (n = 45): APD only). Magnetic resonance imaging (MRI) was used to assess patients with APD and OCF from the medial patella. All patients were treated with a supervised course of immobilization followed by progressive range of motion and strength exercise protocol. History of a recurrent dislocation, radiologic and functional scores were analyzed.

Results

Redislocation rate was 31.2% in group 1 and 26.6% in group 2, showing no significant difference between the two groups (p = 0.690). Intergroup differences in terms of final Kujala and IKDC scores were not significant (p = 0.117 and p = 0.283, respectively). Fracture sites of the patella in group 1 were classified as follows: patellar medial margin (12), inferomedial facet (7), and inferomedial facet involving central ridge (5). In the subgroup of patient with OCF of the inferomedial facet of the patella, the fragments were found in the lateral gutter and did not cause pain or mechanical symptoms. Thus, loose body removal was not performed. However, all five patients with large OCF involving the central ridge of the patella failed non-operative treatment with recurrent dislocations, ultimately requiring fragment refixation and medial retinacular imbrication.

Conclusions

First, APD patients with OCFs of medial margin or inferomedial facet showed similar redislocation rates and functional knee scores with those without OCFs after conservative treatment. Second, initial conservative treatment failed in some APD patients with large OCF, especially when OCFs were fractured from inferomedial facet involving central ridge. Surgery should be considered with this type.

Medial Patellotibial Ligament Reconstruction Improves Patella Tracking When Combined With Medial Patellofemoral Reconstruction: An In Vitro Kinematic Study

PURPOSE

To investigate the isolated and combined effects of medial patellofemoral ligament (MPFL) and medial patellotibial ligament (MPTL) deficiency and reconstruction on patellofemoral kinematics.

METHODS

Sixteen matched-paired female cadaveric knee specimens with a mean age of 53.5 years (range, 26-65) were tested in 5 conditions: (1) intact, (2) MPFL or MPTL cut, (3) MPFL and MPTL combined cut, (4) MPFL or MPTL reconstruction, and (5) MPFL and MPTL combined reconstruction. Dynamic testing allowed continuous analysis of kinematics from 0° to 90° of knee flexion. Knees were also tested statically using a lateral load of 45 N at 0°, 30°, 60°, and 90° of flexion. In both dynamic and static loading tests, a motion capture system detected patellar position for each testing state to distinguish changes in patellar kinematics. Random-intercepts linear mixed-effects models were used to compare patellar kinematics.

RESULTS

The MPFL is the primary restraint to lateral translation of the patella at all knee flexion angles. MPTL deficiency alone did not create significant patella instability, but further increased instability when the MPFL was deficient. Isolated MPFL and combined reconstruction provided improved stability. Through full range of motion native patella tracking was best recreated with combined ligament reconstruction.

CONCLUSIONS

The MPFL plays the greatest role in medial patellar stability, but the MPTL appears to have an influence on patella tracking. This study provides further understanding to the impact of the MPFL and MPTL on patellofemoral motion with implications for reconstruction to improve stability and optimize patellofemoral tracking.

CLINICAL RELEVANCE

This study provides further understanding of the role of the MPFL and MPTL on patellofemoral motion with implications for reconstruction to improve stability and optimize patellofemoral tracking.

Editorial Commentary: As Nature Intended: Will Inclusion of the Medial Patellotibial Ligament Create a Better Medial Patellofemoral Complex Reconstruction?

The medial patellofemoral complex, composed predominantly of the medial patellofemoral ligament, plays an important role in patellar tracking and stability. Medial patellofemoral ligament reconstruction is accordingly one of the most broadly applied surgical techniques for treating patellar instability. Orthopaedic research has demonstrated that surgeries that restore native anatomy are often more effective. The medial patellotibial ligament clearly serves an important supporting role in patellar tracking and stability, particularly in early flexion, and its inclusion in medial soft-tissue reconstructions more closely restores native patella tracking. Whether reconstructions incorporating the medial patellotibial ligament will translate to improved outcomes remains unclear.

Is Diagnostic Arthroscopy at the Time of Medial Patellofemoral Ligament Reconstruction Necessary?

Background:

Although medial patellofemoral ligament (MPFL) reconstruction is well described for patellar instability, the utility of arthroscopy at the time of stabilization has not been fully defined.

Purpose:

To determine whether diagnostic arthroscopy in conjunction with MPFL reconstruction is associated with improvement in functional outcome, pain, and stability or a decrease in perioperative complications.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients who underwent primary MPFL reconstruction without tibial tubercle osteotomy were reviewed (96 patients, 101 knees). Knees were divided into MPFL reconstruction without arthroscopy (n = 37), MPFL reconstruction with diagnostic arthroscopy (n = 41), and MPFL reconstruction with a targeted arthroscopic procedure (n = 23). Postoperative pain, motion, imaging, operative findings, perioperative complications, need for revision procedure, and postoperative Kujala scores were recorded.

Results:

Pain at 2 weeks and 3 months postoperatively was similar between groups. Significantly improved knee flexion at 2 weeks was seen after MPFL reconstruction without arthroscopy versus reconstruction with diagnostic and reconstruction with targeted arthroscopic procedures (58° vs 42° and 48°, respectively; P = .02). Significantly longer tourniquet times were seen for targeted arthroscopic procedures versus the diagnostic and no arthroscopic procedures (73 vs 57 and 58 min, respectively; P = .0002), and significantly higher Kujala scores at follow-up were recorded after MPFL reconstruction without arthroscopy versus reconstruction with diagnostic and targeted arthroscopic procedures (87.8 vs 80.2 and 70.1, respectively; P = .05; 42% response rate). There was no difference between groups in knee flexion, recurrent instability, or perioperative complications at 3 months. Diagnostic arthroscopy yielded findings not previously appreciated on magnetic resonance imaging (MRI) in 35% of patients, usually resulting in partial meniscectomy.

Conclusion:

Diagnostic arthroscopy with MPFL reconstruction may result in findings not previously appreciated on MRI. Postoperative pain, range of motion, and risk of complications were equal at 3 months postoperatively with or without arthroscopy. Despite higher Kujala scores in MPFL reconstruction without arthroscopy, the relationship between arthroscopy and patient-reported outcomes remains unclear. Surgeons can consider diagnostic arthroscopy but should be aware of no clear benefits in patient outcomes.

Patellar stabilization surgeries in cases of recurrent patellar instability: a retrospective clinical and radiological audit

BACKGROUND

Patellar instability is a disabling condition that limits the functional ability and physical aspirations of patients. There are multiple anatomical structures which stabilize the patella and surgical treatment is tailored to repair the underlying aetiology.

AIMS

To evaluate the clinical and radiological outcome of patellar stabilization procedures in patients with recurrent patellar instability.

METHODS

We analysed 34 patients (36 knees) (mean age, 26.6) with recurrent patellar instability who underwent patellar stabilization surgery from June 2009 to September 2014. Type of procedure was dependent on the concomitant aetiological factors; tibial tuberosity osteotomy (61.76%), medial patellofemoral ligament reconstruction (67.64%), lateral release (5.88%) and trochleoplasty (2.94%). Mean follow-up was 3 years (range 9 months-6 years).

RESULTS

At follow-up, 77% of patients were satisfied with the overall outcome of the procedure. The mean IKDC was 66.7, Lysholm 74.9. Mean patellar height decreased significantly (P < .05) to anatomical values. Pre-operatively, the mean tibial tuberosity-trochlear groove distance was 14.66 mm (55.6% at borderline/abnormal level) and 81% showed evidence of trochlear dysplasia. Complications were found in 3 patients (8.33%), 2 of which had further episodes of instability.

CONCLUSIONS

Patellar stabilization surgery is an effective method of treating patellar instability, resulting in stability of the knee in 94.4%. Despite this, patient dissatisfaction rates are quite high suggesting that this patient group, whilst mostly stable, remains significantly symptomatic from their knee. These positive results which are reflected in the recent literature represent a strong case for consideration of primary surgical stabilization in cases of patellar instability.

Combined medial patellofemoral and patellotibial reconstruction with soft tissue fixation in recurrent patellar dislocation

INTRODUCTION

The medial patellofemoral and patellotibial ligaments (MPFL and MPTL) are the main passive restraints to lateral patellar translation. When nonoperative management of patellofemoral dislocations fails, surgical options can be considered to restore patellofemoral stability. Several reconstruction procedures of the MPFL with semitendinosus, gracilis, quadriceps tendon, and synthetic grafts have been described. No clear superiority of one surgical technique over another is evident.

MATERIALS AND METHODS

Patients who suffered at least two documented episodes of unilateral patellar dislocation, confirmed radiographically and at clinical examination, underwent combined MPFL and MPTL reconstruction. Patients were regularly followed-up postoperatively at 2, 4, 8, 12, and 24 weeks, and then annually for a minimum of 2.5 years. Clinical and functional evaluations were performed using the modified Cincinnati rating system and the Kujala score, while anthropometry values including thigh volume and cross-sectional area of the thigh were measured before the operation and at the latest follow-up bilaterally.

RESULTS

There were 7 males and 27 females with a mean age of 26.5 ± 10.7 years (range, 13-39 years). The mean follow-up was 3.1 years (range, 2.5-4 years). The mean modified Cincinnati score Increased from 51 ± 22 preoperatively to 90 ± 19 (P = .001). The mean Kujala scores increased from 47 ± 17 preoperatively to 82 ± 17 (P = .02), with no significant differences between patients with or without osteochondral lesions (P ≥ .05), and between male and female patients (P ≥ .08). The Insall-Salvati index was 1.1 preoperatively and remained within normal range (P = .05) at the latest follow-up.

CONCLUSION

Combined reconstruction of MPFL and MPTL using an ipsilateral autologous gracilis tendon is satisfactory and effective and can be considered as suitable management option to treat recurrent dislocation of the patella. However, randomized studies are needed to compare different techniques.

STUDY DESIGN

Case series.