Current concepts of lateral patella dislocation

Hoffa's Fracture with Associated Injuries Around the Knee Joint: An Approach to a Rare Injury

Fractures of the distal femur typically occur in the axial and sagittal planes. A Hoffa fracture is a coronal plane fracture of the femoral condyle, which accounts for 8.7% to 13% of distal femoral fractures. It is usually associated with other injuries around the knee joint and hence is often missed. We conducted a comprehensive systematic review of papers published in the English language using PubMed, Web of Science, Scopus, and the Cochrane Database, which reported Hoffa's fracture associated with other injuries around the knee joint. We selected 11 eligible papers for final analysis and review. These papers had 12 patients with Hoffa’s fracture, with associated injuries around the knee joint. The associated injuries with Hoffa’s fracture were in the ipsilateral distal femur, proximal tibia fractures, patellar dislocation, patella fracture, and patellar tendon incarceration. The management principles for Hoffa's fracture with associated injuries around the knee joint are: having a high clinical index of suspicion for these injuries, obtaining all trauma series radiographs and computed tomography of the knee, achieving complete articular incongruity, and restoring the functions of the knee joint.

Unilateral anterior knee pain is associated with increased patellar lateral position after stressed lateral translation

PURPOSE

To objectively compare side-to-side patellar position and mobility in patients with idiopathic unilateral anterior knee pain (AKP) using a stress-testing device concomitantly with magnetic resonance imaging. It is hypothesized that the painful knees present greater patellar mobility than the contralateral non-painful knees.

METHODS

From a total sample of 359 patients, 23 patients with idiopathic unilateral AKP (30.9 years, 23.4 kg/m², 43% males) were included within the present study. Both knees of all the patients were examined by conventional imaging, including the measurement of trochlear sulcus angle, Caton-Deschamps index, tibial tuberosity to trochlear groove distance, patellar tilt angle and patellar subluxation (both at rest and upon quadriceps contraction). Additionally, the same patients underwent stress testing (Porto Patella Testing Device); these measurements were taken with the patella at rest, after lateral patellar translation and after lateral patellar tilt. Clinical and functional outcomes were obtained using physical examination and the Kujala and Lysholm scores.

RESULTS

Painful knees showed statistically significant higher patellar lateral position after stressed lateral translation than non-painful knees (p = 0.028), 9.8 ± 3.6 mm and 7.1 ± 6.3 mm, respectively. The adjusted multivariate logistic model identified the patellar position after lateral displacement to be significantly associated with AKP (OR = 1.165) and the model (AUC = 0.807, p < 0.001) showed reasonable sensitivity (67%) and specificity (73%).

CONCLUSION

Patients with idiopathic unilateral AKP with morphologically equivalent knees showed statistically significant increased patellar lateral position after stressed lateral displacement in their painful knee. The greater lateral patellar mobility quantified by the PPTD testing brings more objectivity to the diagnosis.

LEVEL OF EVIDENCE

II.

Surgical treatment is better than non-surgical treatment for primary patellar dislocation: a meta-analysis of randomized controlled trials

BACKGROUND

At present, the best treatment for primary patellar dislocation (PPD) has not been unified. Moreover, meta-analyses comparing the non-surgical and surgical treatments of PPD are lacking. Thus, we aimed to compare the clinical efficacy of surgical or non-surgical treatment of PPD.

METHODS

Randomized controlled studies of surgical and non-surgical treatments of PPD from 1966 to 2018 were retrieved from the following databases: PubMed, EMBASE, Cochrane Library, Wanfang Database, China Knowledge Network, Google Scholar, and Weipu Database. We screened for literature that met the inclusion criteria and extracted useful data for our meta-analysis.

RESULTS

Nine studies, involving 492 patients, met the inclusion criteria and were analyzed in this study. The recurrence rate of patellar dislocation in the surgical group was lower than that in the non-surgical group (P = 0.04]). Subgroup analysis according to the follow-up time showed that the Kujala score (P < 0.001) and lower recurrence rate of dislocation (P = 0.05) than the non-surgical group in the short term. Subgroup analysis according to surgical year showed that the surgical group get higher Kujala score (P < 0.001) and lower recurrence rate of dislocation (P = 0.01) than the non-surgical group in recent years.

CONCLUSION

Surgical treatment can provide better clinical results in a short period of time, and patients may achieve good results within 10 years owing to the advances in surgical techniques and instruments. Thus, we recommend surgical treatment as the preferred treatment for primary patellar dislocation.

Management of the First Patellar Dislocation: A Narrative Review

First patellar dislocation is a common injury of the knee, involving often adolescents and the active population. The consequences of the first episode can be various and potentially disabling. Among these, acute patellar dislocation can often result in recurrent patellar instability. Recurrent patellar instability is certainly multifactorial but depends primarily on the injury of the medial patellofemoral ligament (MPFL), the major soft-tissue stabilizer of the patella. Some classifications are extremely useful in establishing the diagnosis and therapy in patellofemoral disease, in particular in terms of instability. Among those, Henri Dejour and WARPS (weak atraumatic risky anatomy pain and subluxation)/STAID (strong traumatic anatomy normal instability and dislocation) classifications are certainly the most frequently used. There is no clear agreement on the management of the first patellar dislocation. A conservative approach seems to be the first choice in most of cases, but the presence of patellar displacement or osteochondral fractures makes surgery mandatory at the beginning. In addition, there is no clear consensus on which surgical strategy should be used to approach first dislocation, in relation to the possible variation in location of the MPFL injury, and to the eventual presence of preexisting predisposing factors for patellar instability. MPFL reconstruction may theoretically be more reliable than repair, while there is no clear evidence available that osseous abnormality should be addressed after the first episode of patellar dislocation. A narrative review was conducted to report the etiology, the diagnosis and all the possible treatment options of the first patellar dislocation. Modern classifications of the patellofemoral instability were also presented.

Concepts of the Distal Medial Patellar Restraints: Medial Patellotibial Ligament and Medial Patellomeniscal Ligament

The important medial patellar ligamentous restraints to lateral dislocation are the proximal group (the medial quadriceps tendon femoral ligament and the medial patellofemoral ligament) and the distal group [medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML)]. The MPTL patellar insertion is at inferomedial border of patella and tibial insertion is in the anteromedial tibia. The MPML originates in the inferomedial patella, right proximal to the MPTL, inserting in the medial meniscus. On the basis of anatomy and biomechanical studies, the MPTL and MPML are more important in 2 moments during knee range of motion: terminal extension, when it directly counteracts quadriceps contraction. In a systematic review on MPTL reconstructions 19 articles were included detailing the clinical outcomes of 403 knees. All were case series. Overall, good and excellent outcomes were achieved in >75% of cohorts in most studies and redislocations were <10%, with or without the association of the medial patellofemoral ligament. The MPTL is a relevant additional tool to proximal restraint reconstruction in select patient profiles; however, more definitive clinical studies are necessary to better define surgical indications.

Medial patellofemoral ligament (MPFL) reconstruction technique using an epiphyseal femoral socket with fluoroscopic guidance helps avoid physeal injury in skeletally immature patients

PURPOSE

The purpose of this study was to assess the physeal safety associated with the use of an epiphyseal femoral socket for paediatric medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Fifty-four knees in 49 skeletally immature patients underwent physeal-sparing MPFL reconstruction performed by 1 surgeon at a tertiary care academic medical centre from 2007 to 2016. A femoral socket distal to the femoral physis was used for graft fixation in all the patients. To assess physeal safety, all included patients either had post-operative MRIs of the operative knee or standing hip-to-ankle radiographs. Physeal safety was assessed on MRI, and the distance between the femoral socket relative to the physis was measured at both the aperture and the end of the socket. Development of lower limb angular deformities and/or limb length discrepancy (LLD) was evaluated using post-operative standing hip-to-ankle radiographs, patient records, and clinical assessments.

RESULTS

The mean age at time of surgery was 13.3 ± 1.6 years. The median length of radiographic follow-up was 2.2 years (range 1.0-5.7 years). At most recent clinical follow-up, five patients (9.3%) had recurrent patellar instability, with three patients (5.6%) undergoing subsequent tibial tubercle osteotomy or revision MPFL reconstruction. There was no statistically significant difference in leg length between operated and non-operated extremities (n.s.). There was no statistically significant difference between non-operated and operated mMPTA (n.s.) and mLDFA (n.s.) measurements. On post-operative MRI, there was no evidence of physeal arrest. The median distance from the physis to the socket at the aperture and distal end of the femoral socket were 5.9 mm (range 1.9-12) and 7.1 mm (1.3-12.4), respectively.

CONCLUSION

These results demonstrate that with fluoroscopic guidance, placing the femoral socket distal to the distal femoral physis is an effective method for avoiding physeal injury and subsequent growth disturbances in children with patellar instability. Clinically, this information is essential in optimal surgical management of these patients, as this technique allows for femoral fixation of the MPFL reconstruction graft within the epiphysis while also preserving normal growth.

LEVEL OF EVIDENCE

Level IV-case series.

Relationship Between Lateral Patellar Stability Following Tibial Tubercle Osteotomy for Varying Patellofemoral Geometries

The geometry of the patellofemoral joint affects function and pathology. However, the impact of trochlear groove depth on treatments for patellar instability and pain is not clear. Tibial tubercle osteotomy is a common surgical intervention for patellar instability where the tibial insertion of the patellar tendon is translated to align the extensor mechanism and stabilize the joint. The aim of this work was to investigate the interaction between trochlear groove depth and patellar tendon insertion and their effect on patellar stability. Patellofemoral geometry was modified based on a statistical shape model to create knees with a range of trochlear groove depths. A Monte Carlo approach was used and 750 instances of a musculoskeletal model were generated with varying geometry and anterior and medial transfer of the patellar tendon. Stability was assessed by applying a lateral perturbation force to the patella during simulation of overground walking. In knees with deep trochlear grooves, a medialized patellar tendon increased stability. However, in knees with shallow trochlear grooves, stability was maximized for tendon insertion ~1 mm medial to its neutral location. This patellar tendon insertion also corresponded to the best alignment of the patella in the trochlear groove in these knees, indicating that good alignment may be important to maximizing stability. Anterior patellar tendon transfer had minimal effect on stability for all geometries. A better understanding of the effects of articular geometry and tubercle location on stability may aid clinicians in patient-specific surgical planning.

Influence of Risky Pathoanatomy and Demographic Factors on Clinical Outcomes After Isolated Medial Patellofemoral Ligament Reconstruction: A Regression Analysis

BACKGROUND

Multiple studies have demonstrated that a number of demographic and pathoanatomic characteristics are associated with patellofemoral instability, recurrence of instability, and less satisfactory results following medial patellofemoral ligament reconstruction (MPFL-R). Despite the growing volume of research, the relationship of risk factors to patient-reported outcome after MPFL-R is unclear.

PURPOSE

To determine if certain pathoanatomic and demographic factors predict disease-specific quality-of-life outcome after isolated MPFL-R for symptomatic patellofemoral instability.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The study analyzed 224 isolated MPFL-Rs. Demographic data were collected, including age at first dislocation, sex, and presence of bilateral instability. Pathoanatomic risk factors included the presence of high-grade trochlear dysplasia, tibial tubercle-trochlear groove (TT-TG) distance, patella alta ratio, Beighton score, and patellar tilt. Other factors included femoral tunnel position accuracy and WARPS/STAID score. Descriptive analyses were conducted, followed by calculation of individual Spearman rank correlation coefficients for the predictor variables versus the Banff Patellofemoral Instability Instrument (BPII) scores. A multivariable regression with stepwise selection was employed to establish the final model predicting BPII score, with all significant variables for alpha ≤ .05 included in the final model.

RESULTS

The cohort of 224 patients included 66 (29.5%) males and 158 (70.5%) females, with a mean age of 24.1 years and a mean body mass index of 23.9 kg/m². The mean age of first patellar dislocation was 15.7 years, and 41.4% of patients had bilateral instability. Pathoanatomic variables within the cohort included the following: high-grade trochlear dysplasia = 41%; mean TT-TG = 14.6 mm, with 16.8% of patients demonstrating a TT-TG ≥18 mm; mean Caton-Deschamps ratio = 1.09, with 22% of patients demonstrating a ratio ≥1.2; and positive Beighton score = 37.5%. The mean BPII score at postoperative 2 years was 67.1 out of 100. A stepwise elimination in the regression model demonstrated no statistically significant 3- or 2-way relationships. Assessment of individual variables indicated that bilateral symptoms (P = .004), higher age at first dislocation (P = .024), and femoral tunnel position >10 mm from the Schöttle point (P = .042) were statistically significant predictors of lower quality-of-life scores. The R² value for the regression analysis model was 0.07.

CONCLUSION

In this large cohort of patients undergoing isolated MPFL-R for symptomatic lateral patellofemoral instability, a multivariable forward stepwise regression demonstrated that bilateral symptoms, femoral tunnel position, and age at first dislocation were statistically significant predictors of lower postoperative BPII scores. No anatomic risk factors were predictive of quality-of-life outcome score 2 years after MPFL-R surgery. The R² value indicated that there were many other important contributing factors affecting BPII outcome scores than those explored in this study.

Traumatic bilateral medial patellar instability in a 15-year-old girl

Introduction:

Patellar dislocation encompasses the 2–3% of the knee joint injuries, and lateral patellar luxation is by far more common than the medial one. Medial patellar dislocation is described only by few reports and generally as a consequence of previous surgeries. The purpose of this case report is to describe the surgical management of a rare case of traumatic bilateral medial patellar dislocation in a 15-year-old girl with no previous patellofemoral surgeries.

Case Report:

The patient underwent a traumatic medial patellar dislocation on the left knee, and 18 months later also on the right one. In both cases, the first proposed treatment was a conservative therapy, encompassing the use of a brace and muscular imbalance correction. After a 6-month period, the patient still referred to the persistent sensation of “giving away,” so surgery was advised. The surgical operation consisted of an open medial retinacular release with complete dissection of the hypertrophic medial patellofemoral ligament and a transfer of the vastus medialis oblique to the superior border of the patella. Seven years after surgery, the patient declared to be satisfied with the procedure, referring only slight difficulty in squatting, jumping, and running. So far, no further episodes of dislocation occurred.

Conclusions:

The present case report showed the favorable result of surgical correction of a unique case of bilateral non-iatrogenic medial patellar luxation, in the absence of any underlying bony-structural abnormality. No other papers dealing with medial traumatic bilateral patellar dislocation are found in current literature.

Anatomic Magnetic Resonance Imaging Measurements in First-Time Patellar Dislocators by Sex and Age

CONTEXT

Anatomic differences of the knee in first-time patellar dislocators have not been clearly elucidated.

OBJECTIVE

To compare structural differences of the knee in those who have sustained an acute first-time patellar dislocation resulting in a medial patellofemoral ligament (MPFL) tear by sex and age (≤17 years old, ≥18 years old).

DESIGN

Case series.

SETTING

Retrospective magnetic resonance imaging analysis.

PATIENTS OR OTHER PARTICIPANTS

Thirty-five acute first-time patellar dislocators with an associated MPFL tear.

MAIN OUTCOME MEASURE(S)

Patellar height using 3 methods, patellar alignment using congruency angles, and trochlear morphology using the sulcus angle. We compared the means of these variables by sex and age. The intraclass correlation coefficient was then calculated to assess the agreement of the independent reviewers.

RESULTS

A total of 21 left and 14 right knees were analyzed. The MPFL tear location did not differ by sex (P = .34) or age (P = .43). Patellar height did not differ as measured by the Caton-Deschamps ratio (P = .29 for sex, P = .49 for age), Insall-Salvati index (P = .15 for sex, P = .33 for age), or patellotrochlear index (P = .67 for sex, P = .49 for age). The congruence angle (P = .81 for sex, P = .06 for age) and trochlear morphology as measured by the sulcus angle (P = .64 for sex, P = .45 for age) were similar between groups.

CONCLUSIONS

Patellar height and trochlear morphology did not differ by sex or age among patients whose first-time patellar dislocations resulted in an MPFL tear. In addition, the location of the tear did not appear to vary by sex or age.

Surgical management for recurrent patellar dislocations in skeletally immature patients

BACKGROUND

Due to his multifactorial aetiology, treating patellofemoral instability can be a challenge for the orthopaedic surgeon. The incidence of patellofemoral instability shows a peak during adolescence, especially from 11 to 14 years old.

AIM

Several clinical studies focusing on recurrent patellar dislocations in skeletally immature patients have been published, reporting inconsistent or controversial results. Currently, there is a lack of consensus regarding the surgical management of these patients. The purpose of this study is to update current evidence and systematically review indications, treatments, and outcomes of surgical management for recurrent patellar dislocations in skeletally immature patients.

METHODS

A comprehensive review of the literature was performed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis, the PRISMA Statement. The following electronic databases were accessed in February 2019: PubMed, Scopus, Google Scholar, CINAHL, EMBASE. All the articles treating surgical management for recurrent patellar dislocations in skeletally immature patients were considered for inclusion. For the methodological quality assessment, we referred to the Coleman Methodology Score (CMS). For the statistical analysis, we referred to the unpaired t-test to establish whether the results are statistically significant.

RESULT

The overall CMS resulted in 52.78 points, attesting a satisfactory methodological quality assessment to this systematic review. A total of 21 articles including 623 patients (577 knees) were evaluated. The overall mean age was 13.02 years. The mean follow-up was 46.61 months. The mean Kujala score improved from 58.94 ± 10.38 to 87.07 ± 7.68 points. The Lysholm score reported a pre- and post-operative mean values of 49.54 ± 14.20 and 88.32 ± 8.80, respectively. The mean Tegner Activity Scale scored 4.28 ± 1.22 at baseline, improving to 5.26 ± 0.83 post-operatively. A total of 4.19% of patients incurred into a major complication, while 9.6% sustained a minor one. We observed a total of 89 re-dislocations above 692 treated knees (12%).

CONCLUSION

The main findings of this study are that surgical procedures for skeletally immature patients affected by recurrent patellar dislocations are feasible and effective. Complications and re-dislocations occurred infrequently. It is of fundamental importance to treat precociously these patients in order to reduce the risk of further recurrences, to increase the level of sporting activity and improving the quality of life.

Distal alignment procedures for patellofemoral instability: comprehensive review of the literature

Patellofemoral disorders are a common cause of complaint in adolescent patients. Several distal realignment procedures performed in isolation or combination with proximal alignment have been described. To clarify the role of distal alignment for patellofemoral instability, a systematic review of the literature was conducted. Two independent reviewers accessed the following databases: PubMed, Medline, CINAHL, Cochrane, EMBASE and Google Scholar. A total of 1478 patients with a mean age of 22.78 years were included. The mean follow-up was 86.53 months. The average Kujala score improved from 57.66 to 82.73. The average Lysholm score improved from 63.25 to 87.87, and the average Tegner score from 3 to 4.16. VAS score improved from an average 8 to 2.56. We account a total of 46 major complications, 45 minor complications and 95 recurrences. The risk of a recurrence is 6.42%. A total of 122 additional surgeries were performed during the follow-up. This systematic review of literature suggests the importance to identify the pathological background that predisposes patients for developing patellofemoral instability and its implications for the decision-making process. The optimal treatment for patellofemoral instability should be individualized to address the specific anatomical abnormalities that contribute to patellofemoral dislocations. Distal alignments are a feasible solution to restore correct patellar biomechanics and tracking, leading to an improvement of patients' quality of life.

Plaster, splint, brace, tape or functional mobilization after first-time patellar dislocation: what's the evidence?

With an incidence of 5.8 per 100,000 per year, patellar dislocations are commonly seen in the emergency department. Surprisingly, there are only a few studies available that focus on the results of the different non-surgical treatment options after first-time patellar dislocation. The aim of this review is to provide an overview of the most recent and relevant studies on the rationales and results of the non-surgical treatment for first-time patellar dislocation.

Patellar instability mainly affects young and active patients, with a peak incidence of 29 per 100 000 per year in adolescents. The medial patellofemoral ligament, a main passive restraint for lateral translation of the patella, is torn in lateral patellofemoral dislocations. Treatment of first-time patellar dislocation can be either conservative or surgical.

There are two options in conservative management of first-time patellar dislocation: immobilization using a cylinder cast or removable splint, or, second, functional mobilization after applying a brace or patellar tape.

The current available literature of conservative treatment after a first-time patellar dislocation is little and of low quality of evidence. Conclusions should be drawn with care, new research focussing on non-surgical treatment is therefore strongly needed.

Cite this article: EFORT Open Rev 2019;4:110-114. DOI: 10.1302/2058-5241.4.180016

Patellofemoral Instability in Children: Correlation Between Patellofemoral Incongruence, Mechanism of Injury, and Cartilage Damage

OBJECTIVE. The objective of our study was to assess correlation between patellofemoral incongruency and injury mechanism, recurrence, bilaterality, and cartilage damage in patients with patellofemoral instability (PFI). MATERIALS AND METHODS. Ninety-four knee MRI examinations (10 bilateral) of 84 patients with PFI (47 female and 37 male patients; mean age ± SD, 15.0 ± 2.5 years) who had patella dislocation and medial patellofemoral ligament reconstruction (MPFLR) and 66 examinations of age- and sex-matched control subjects were reviewed. The PFI group was subclassified on the basis of injury, recurrence, and bilaterality. Patellofemoral congruence was assessed in both groups with the following MRI measurements: lateral femoral trochlear inclination angle, femoral sulcus depth, medial-to-lateral facet ratio, distance between tibial tuberosity (TT) and trochlear groove (TG), and patellar tendon ratio. Patella cartilage damage was assessed in the PFI group using conventional MRI (International Cartilage Repair Society grade 0-4) and T2 relaxation time mapping at three locations. MRI measurements were compared between groups and subgroups (Wilcoxon rank sum test) and were correlated with cartilage damage (Spearman correlation). RESULTS. All MRI measurements were significantly different between the group with PFI and the group without PFI (p < 0.0001). The bilateral PFI group had significantly increased TT-TG distance (mean, 15.9 vs 13.1 mm, p < 0.05) and patellar tendon ratio (mean, 1.6 vs 1.4, p < 0.05) compared with the unilateral PFI group. The TT-TG distance positively correlated with T2 values of medial and lateral patella cartilage. There were no differences between other subgroups and no correlation between other MRI measurements and the severity of cartilage damage. CONCLUSION. In patients with PFI, the severity of patellofemoral incongruence was not associated with injury mechanism or cartilage damage. However, increased lateralization of the patellar tendon (TT-TG distance) and patella alta (patellar tendon ratio) correlated with injury to the contralateral knee requiring bilateral MPFLR.

Early functional rehabilitation after patellar dislocation-What procedures are daily routine in orthopedic surgery?

INTRODUCTION

Patellar dislocation and rupture of the medial patellofemoral ligament (MPFL) are frequently seen in daily orthopedic practice. Besides initial non-surgical treatment, surgery and subsequent rehabilitation are crucial for restoring stability in the femoropatellar joint. This study investigated current rehabilitation strategies after patellar dislocation because knowledge on this topic has been severely limited so far.

MATERIALS AND METHODS

The current rehabilitation protocols of 42 orthopedic and trauma surgical institutions were analyzed regarding their recommendations on weight bearing, range of motion (ROM), and use of movement devices and orthosis. All protocols for conservative treatment and postoperative rehabilitation after MPFL reconstruction were compared. Descriptive and statistical analyses were carried out when appropriate.

RESULTS

The different rehabilitation strategies for conservative and surgical treatment after patellar dislocation showed a tendency towards earlier functional rehabilitation after surgical MPFL reconstruction than after conservative treatment. Both surgical and conservative treatment involved initial restrictions in weight bearing, ROM, and use of movement devices and orthosis at the beginning of rehabilitation. The rehab protocols showed a significant earlier full weight bearing after surgical MPFL reconstruction (p > 0.001). Due to the presence of other parameters for early functional treatment, the absence of an indication for using orthosis (surgical: 44%, conservative: 33%; p = 0.515) or start of unlimited ROM of the knee (surgical: 4.9 weeks, conservative: 5.7 weeks; p = 0.076) showed by trend an earlier functional strategy after MPFL reconstruction than after conservative therapy.

CONCLUSIONS

Both conservative and surgical treatment after patellar dislocation showed restrictions in the early phase of the rehabilitation. Earlier functional therapy was more common after MPFL reconstruction than after conservative treatment. Further clinical and biomechanical studies on rehabilitation strategies after patellar dislocation are needed to improve patient care und individualized therapy.

The Recurrent Instability of the Patella Score: A Statistically Based Model for Prediction of Long-Term Recurrence Risk After First-Time Dislocation

PURPOSE

To describe the clinical history of a series of primary, lateral patellar dislocations and determine long-term predictors of recurrent instability while accounting for patients undergoing early operative management.

METHODS

A large geographic database of more than 500,000 patients was used to identify patients who sustained a first-time lateral patellar dislocation between 1990 and 2010. Charts were individually reviewed to document demographics, radiographic measures including tibial tubercle to trochlear groove distance (TT-TG) and patellar length (PL), recurrent episodes of instability, and patellar stabilization surgery. A risk score that accounted for early surgical management was calculated using Fine and Gray competing risk regression, and its ability to stratify patients was examined using cumulative incidence curves.

RESULTS

Eighty-one patients (mean age 19.9 ± 9.4 years, 38 male, 43 female) were identified and followed for a mean of 10.1 years (range 4.1-20.2). Thirty-eight patients (46.9%) experienced an episode of recurrent instability and 30 (37.0%) underwent patellar stabilization surgery, including 7 who did so before recurrent dislocation. A multivariate, statistically derived scoring system, the Recurrent Instability of the Patella Score (RIP Score), that employed age, skeletal maturity, trochlear dysplasia, and TT-TG/PL ratio to predict recurrent instability while accounting for patients managed surgically, was generated. The resulting RIP score stratified patients into low-, intermediate-, and high-risk categories, with 0.0%, 30.6%, and 79.2% 10-year recurrent instability rates, respectively (P = .000004), and an area under the curve of 0.875 (P = .00002).

CONCLUSIONS

Patients who sustain a first-time, lateral patellar dislocation can be readily classified into low-, intermediate-, and high-risk categories employing the RIP score based on age, skeletal maturity, trochlear dysplasia, and TT-TG/PL ratio. This long-term risk stratification holds significant potential clinical utility for determination of patients who are at high risk for recurrent instability after primary patellar dislocation. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Autologous mesenchymal stem cell application for cartilage defect in recurrent patellar dislocation: A case report

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This is a novel management of a 21-year-old male with recurrent patellar dislocation.

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Fulkerson procedure was to realign the patella.

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Mesenchymal stem cell application was used for the articular cartilage defect.

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The outcome of this combination treatment was satisfying.

Introduction

Recurrent patellar dislocation can lead to articular cartilage injury. We report a 21-year old male with left patella instability and articular cartilage defect.

Presentation of case

A 21-year-old male presented with left patellar instability and pain. Knee range of motion (ROM) was limited when patella was dislocated (0–20°). The J-sign positive, patellar apprehension test was positive, with medial patella elasticity/patellar glide >2 quadrants. The Q angle, in the 90° flexed knee position was still normal. The plain radiograph imaging showed no abnormality. Insall-Salvati index was 1.12. The patient was diagnosed with recurrent patellar dislocation and cartilage lesion of the left knee, and was treated with combining Fulkerson osteotomy with the lateral retinacular release and percutaneous medial plication, followed by microfracture procedure and MSCs implantation.

Discussion

Recurrent patellar dislocation is uncommon problem while cartilage lesions following recurrent patellar dislocations are quite common, but still no consensus on the management.

Conclusion

Combination of Fulkerson osteotomy with the lateral retinacular release and percutaneous medial plication was effective in treating chronic patellar instability. The microfracture procedure and MSCs implantation was safe and could improve the cartilage regeneration in patients with articular cartilage defect due to recurrent patellar dislocation.

Recurrent Patellar Instability: Implications of Preoperative Patellar Crepitation on the Status of the Patellofemoral Articular Cartilage

BACKGROUND

The purpose of the study was to quantify the frequency, severity, and location of patellofemoral (PF) articular cartilage changes recurrent patellar instability treated surgically in patients with preoperative clinical patellar crepitation.

METHODS

A single-surgeon database was queried for all knees with recurrent patellar instability between 3/2000 and 6/2012 (n=214). Only knees which underwent knee arthroscopy during the surgical treatment were included (n=148). PF articular cartilage condition was assessed arthroscopically.

RESULTS

There were 148 knees in 130 patients (mean age, 16 y), which met inclusion criteria. There were 93 females and 37 males. Diagnoses were dislocations [122 (82.4%)] and subluxations (26). Preoperatively 28 knees (18.9%) had PF crepitation. Statistical analysis demonstrated preoperative PF crepitation was correlated with medial patellar facet lesions (P=0.0022) and were 3.6 times more likely to have medial patellar facet lesions. Crepitation was correlated with the higher outerbridge (OB) patellar grades (P<0.0001) and larger patellar lesion size (P=0.0021). At arthroscopy 89 knees (60.5%) had patellar articular cartilage damage with a mean OB grade of 1.3 (0 to 4) and mean size of 93.2 mm (0 to 750). The femoral articular cartilage was identified in 29 knees (19.7%) with a mean OB grade of 0.44 (0 to 4).

CONCLUSIONS

PF articular damage was present in 63% of knees, which were surgically treated for patellar instability. The patella was involved in 61% (mean, 129 mm) and femoral trochlea in 20% (mean 166 mm) of knees. Knee with preoperative PF crepitation (20% of cohort) more commonly had medial patellar facet lesions with higher OB grades, and larger patellar lesion size than knees without preoperative crepitation. Because of the high frequency of patellar (83%) and femoral (36%) articular damage documented at the time of surgical reconstruction, visualization of the PF joint is recommended when knees have preoperative PF crepitation.

LEVEL OF EVIDENCE

Level IV.

Individualizing the tibial tubercle to trochlear groove distance to patient specific anatomy improves sensitivity for recurrent instability

PURPOSE

An initial episode of patellar instability poses a treatment challenge given the absence of a valid, reproducible, and universally applicable predictor of recurrence. Recently, a series of patellar instability ratios (PIRs) were described. Each ratio consisted of the traditional tibial tubercle to trochlear groove (TT-TG) distance normalized to patient-specific measures. The purpose of this study was to investigate the reliability and validity of these novel measures.

METHODS

Eighty-seven patients experiencing a first-time lateral patellar dislocation were identified in a retrospective manner. Magnetic resonance imaging (MRI) studies obtained at the time of injury were reviewed. The TT-TG distance, patellar width (PW), trochlear width (TW), patellar length (PL), and trochlear length (TL) were obtained by two observers in a blinded, randomized fashion. Measurement reliability was assessed using intra-class correlation coefficients (ICCs). Patients were divided into those having a single dislocation (Group 1) and those experiencing recurrent instability (Group 2). The ability of the TT-TG distance and each PIR to predict recurrent instability was assessed by calculating odds ratios (ORs) with 95% confidence intervals (CIs). Sensitivity and specificity were also calculated for each measure.

RESULTS

Excellent inter-rater agreement was observed with ICCs > 0.75 for all patellofemoral joint measurements obtained on MRI. The TT-TG distance alone was predictive of recurrent patellar instability with an OR of 8.9 (p < 0.001). However, the isolated TT-TG distance had the lowest sensitivity at 25.6%. Among ratios, a TT-TG/PL ≥ 0.5 was the most predictive of recurrent instability with an ORs of 6.1 (p = < 0.001). A TT-TG/TL ≥ 0.8 was also predictive of recurrence (OR 4.9, p = 0.027) and had the highest sensitivity of any measure at 94.9%.

CONCLUSION

The results of the current study support the reproducibility and predictive ability of PIRs. While a TT-TG ≥ 20 mm was the strongest predictor of recurrent patellar instability, it was a relatively insensitive measure. Sensitivity may be improved by normalizing the TT-TG distance to patient-specific axial and sagittal plane patellofemoral measurements on MRI. Ultimately, PIRs are reproducible measures that may serve as an additional tool when clinically assessing the unstable patellofemoral joint.

LEVEL OF EVIDENCE

III.

Operative Repair of Medial Patellofemoral Ligament Injury Versus Knee Brace in Children With an Acute First-Time Traumatic Patellar Dislocation: A Randomized Controlled Trial

BACKGROUND

A lateral patellar dislocation (LPD) is the most common traumatic knee injury with hemarthrosis in children. The redislocation rate is high. Varying operative and nonoperative treatments have been advocated with no consensus on the best treatment.

PURPOSE

(1) To evaluate if arthroscopic-assisted repair of the medial patellofemoral ligament (MPFL) in patients with an acute first-time traumatic LPD would reduce the recurrence rate and offer better objective/subjective knee function compared with a knee brace without repair. (2) To study the presence of anatomic patellar instability risk factors (APIFs) and their association with a redislocation.

STUDY DESIGN

Randomized controlled trial; Level of evidence, 1.

METHODS

This was a prospective series of 74 skeletally immature patients aged 9 to 14 years (38 girls and 36 boys; mean age, 13.1 years) with a first-time traumatic LPD, with clinical examinations, radiographs, magnetic resonance imaging, and diagnostic arthroscopic surgery performed within 2 weeks of the index injury. The child was randomized to either (1) a knee brace (KB group) for 4 weeks and physical therapy or (2) arthroscopic-assisted repair (R group) of the MPFL with anchors, 4 weeks with a soft cast splint, and physical therapy. The follow-up time was 2 years.

RESULTS

The redislocation rate was significantly lower in the R group than in the KB group at final follow-up: 8 patients (22%) versus 16 patients (43%), respectively ( P = .047). The Knee injury and Osteoarthritis Outcome Score for children sport/play and quality of life subscales had lower scores in the R group compared with the KB group; the significant differences were among those with redislocations. The mean Kujala score was excellent in the KB group (95.9) and good in the R group (90.9). An impaired Limb Symmetry Index (median, 83%) for concentric quadriceps torque at 90 deg/s was found only in the R group. Eighty-one percent of the study patients had ≥2 APIFs. Trochlear dysplasia (trochlear depth <3 mm) had the highest odds ratio for redislocations (2.35 [95% CI, 0.69-8.03]), with no significant association between APIFs and a redislocation.

CONCLUSION

Operative repair of an MPFL injury in the acute phase in skeletally immature children with a primary traumatic LPD significantly reduced the redislocation rate but did not improve subjective or objective knee function compared with a knee brace without repair. The majority of the patients in both groups were satisfied with their knee function. There was a high representation of APIFs, which needs to be considered when evaluating the risk of redislocations. Registration: ISRCTN 39959729 (Current Controlled Trials).

Femoral tunnel widening is associated with tunnel malposition but not with clinical failure after medial patellofemoral ligament reconstruction with a free gracilis tendon graft

INTRODUCTION

MPFL reconstruction is widely and successfully used for treating patella instability, either as a standalone procedure or in combination. Although different techniques allow for MPFL reconstruction, the use of a free tendon graft is one of the most commonly used. The phenomenon of tunnel widening or tunnel enlargement is well described in ACL reconstruction, but so far only little effort has been put into evaluating this phenomenon after MPFL reconstruction.

MATERIALS AND METHODS

Patients who received an MPFL reconstruction with a free gracilis tendon graft were identified by review of patient files. Additional clinical examination and magnetic resonance imaging were performed to assess tunnel enlargement and clinical outcome.

RESULTS

Fifty-one knees of 49 patients (34 female, 17 male) with a mean follow-up of 3.0 ± 1.4 years were included in this study. Mean age at the time of surgery was 22.6 ± 8.5 years. Mean Tegner score decreased from preoperative 5.3 ± 2.0 to 4.0 ± 1.4 postoperative. Postoperative IKDC and Kujala scores were 74 ± 16 and 80 ± 15, respectively. Twenty-three patients showed a tunnel enlargement at follow-up examination. Of these 23 patients, 20 showed a tunnel that was positioned too proximal, whereas only 13 of the 28 patients showing no enlargement had a tunnel that was positioned too proximal (p = 0.0033). Interestingly, patients showing a tunnel enlargement at follow-up examination also showed significantly better Kujala (84 ± 12 vs. 75 ± 16; p = 0.03) and IKDC scores (80 ± 7 vs. 70 ± 19; p = 0.02) when compared to the non-enlarged group.

CONCLUSION

Tunnel enlargement after MPFL reconstruction with a free gracilis tendon graft seems to be connected to mechanical overload due to a proximal malposition of the femoral tunnel. Interestingly, this did not influence clinical outcome as patients with tunnel enlargement showed better Kujala and IKDC scores.

Biomechanical Evaluation of the Medial Stabilizers of the Patella

BACKGROUND

Quantification of the biomechanical properties of each individual medial patellar ligament will facilitate an understanding of injury patterns and enhance anatomic reconstruction techniques by improving the selection of grafts possessing appropriate biomechanical properties for each ligament.

PURPOSE

To determine the ultimate failure load, stiffness, and mechanism of failure of the medial patellofemoral ligament (MPFL), medial patellotibial ligament (MPTL), and medial patellomeniscal ligament (MPML) to assist with selection of graft tissue for anatomic reconstructions.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Twenty-two nonpaired, fresh-frozen cadaveric knees were dissected free of all soft tissue structures except for the MPFL, MPTL, and MPML. Two specimens were ultimately excluded because their medial structure fibers were lacerated during dissection. The patella was obliquely cut to test the MPFL and the MPTL-MPML complex separately. To ensure that the common patellar insertion of the MPTL and MPML was not compromised during testing, only one each of the MPML and MPTL were tested per specimen (n = 10 each). Specimens were secured in a dynamic tensile testing machine, and the ultimate load, stiffness, and mechanism of failure of each ligament (MPFL = 20, MPML = 10, and MPTL = 10) were recorded.

RESULTS

The mean ± SD ultimate load of the MPFL (178 ± 46 N) was not significantly greater than that of the MPTL (147 ± 80 N; P = .706) but was significantly greater than that of the MPML (105 ± 62 N; P = .001). The mean ultimate load of the MPTL was not significantly different from that of the MPML ( P = .210). Of the 20 MPFLs tested, 16 failed by midsubstance rupture and 4 by bony avulsion on the femur. Of the 10 MPTLs tested, 9 failed by midsubstance rupture and 1 by bony avulsion on the patella. Finally, of the 10 MPMLs tested, all 10 failed by midsubstance rupture. No significant difference was found in mean stiffness between the MPFL (23 ± 6 N/mm²) and the MPTL (31 ± 21 N/mm²; P = .169), but a significant difference was found between the MPFL and the MPML (14 ± 8 N/mm²; P = .003) and between the MPTL and MPML ( P = .028).

CONCLUSION

The MPFL and MPTL had comparable ultimate loads and stiffness, while the MPML had lower failure loads and stiffness. Midsubstance failure was the most common type of failure; therefore, reconstruction grafts should meet or exceed the values reported herein.

CLINICAL RELEVANCE

For an anatomic medial-sided knee reconstruction, the individual biomechanical contributions of the medial patellar ligamentous structures (MPFL, MPTL, and MPML) need to be characterized to facilitate an optimal reconstruction design.

Avoiding Complications with MPFL Reconstruction

PURPOSE OF REVIEW

To discuss the potentially significant complications associated with medial patellofemoral ligament (MPFL) reconstruction. Additionally, to review the most current and relevant literature with an emphasis on avoiding these potential complications.

RECENT FINDINGS

Multiple cadaveric studies have characterized the anatomy of the MPFL and the related morphologic abnormalities that contribute to recurrent lateral patellar instability. Such abnormalities include patella alta, excessive tibial tubercle to trochlear grove (TT-TG) distance, trochlear dysplasia, and malalignment. Recent studies have evaluated the clinical outcomes associated with the treatment of concomitant pathology in combination with MPFL reconstruction, which is critical in avoiding recurrent instability and complications. Although there remains a lack of consensus regarding various critical aspects of MPFL reconstruction, certain concepts remain imperative. Our preferred methods and rationales for surgical techniques are described. These include appropriate work up, a combination of procedures to address abnormal morphology, anatomical femoral insertion, safe and secure patellar fixation, appropriate graft length fixation, and thoughtful knee flexion during fixation.

Synthetic versus autologous reconstruction (Syn-VAR) of the medial patellofemoral ligament: a study protocol for a randomised controlled trial

Background

Recurrent patellar instability incidence is 5.8/100,000 population, and recurrent dislocations are reported in the range of 15–80%. Recurrent instability is multifactorial and can be associated with disorder of limb alignment, osseous development, congruity of the patella in the trochlea and soft tissue static and dynamic constraints. The multifactorial aetiology makes management challenging, and a lack studies in a heterogeneous population with robust clinical outcomes compounds this further. The options for medial patellofemoral ligament (MPFL) reconstruction include autologous graft reconstruction with semitendinosus tendon, or synthetic polyester woven grafts. In theory, in the young active patient, the surgeon may wish to preserve the hamstring tendons to reduce postoperative morbidity to the patient, reduce delay in recovery from donor site morbidity and preserve the hamstring tendons. There have been no randomised controlled trials (RCTs) to date that directly compare autologous hamstring and synthetic reconstruction methods. This trial aims to assess the functional outcomes in those undergoing MPFL reconstruction with either autologous hamstring graft reconstruction, or a commercially available synthetic polyester open woven tape.

Methods

Following a power calculation using previous studies as the pilot data, a total of 30 patients will be included in the study. Enrolment is based upon strict inclusion/exclusion criteria outlined in the “Methods”. Participants will be randomized to receive either autograft or synthetic graft reconstruction. We aim to recruit 15 patients to each arm of the study. Surgery is performed by a single consultant surgeon experienced in both reconstructive options, using the default surgical technique for each. A postoperative physiotherapist-directed rehabilitation protocol will be implemented, as is routine. The primary outcome is the Kujala functional score and its change over the study period. Data on further secondary outcomes using validated outcomes scores will also be collected, specifically the Tegner and Lysholm, Banff Patellar Instability Index, and ACL Quality of Life Score. Secondary outcomes are complications and revision for any reason. The patient follow-up time is 2 years. The first patient will be recruited in January 2018. The expected trial deadline for recruitment is December 2018, with records and results being held for 5 years.

Discussion

This RCT study is the first to directly compare the efficacy of autograft versus synthetic allograft in MPFL reconstruction and the graft effects on patient-reported clinical outcomes.

Trial registration

ISRCTN, 16657952. Registered on 3 March 2017.

The study protocol has been approved by the Office for Research Ethics Committees of Northern Ireland (ORECNI 17/NI/0129).

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2622-7) contains supplementary material, which is available to authorized users.

Clinical outcomes after revision surgery for medial patellofemoral ligament reconstruction

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is the standard surgical intervention for patella instability. However, limited knowledge exists concerning the causes for failure, and outcome after revision MPFL-R. The purpose of this study is to evaluate the causes of primary MPFL-R failure and clinical outcomes after revision MPFL-R.

METHODS

Twenty-three patients (6 males and 17 females) with failed primary MPFL-R underwent isolated revision MPFL-R or combined revision MPFL-R with tibial tuberosity osteotomy (TTO). The mean age was 23 (SD 8.6). Prior to surgery, dysplasia of the patellofemoral joint, sulcus angle, Insall-Salvati index, cartilage lesions, tibial tuberosity trochlear groove (TTTG) distance, and tunnel placement were evaluated by magnetic resonance imaging (MRI). Their scores on the Kujala Anterior Knee Pain Scale and pain scores were assessed prior to surgery, 1 year post-operatively and at final follow-up. The mean follow-up time was 44 months (median range 39). The radiographic characteristics and clinical outcomes were compared with a 224 primary MPFL-R patient cohort (240 knees).

RESULTS

Non-anatomical fixation of the graft at the medial femoral condyle after primary MPFL-R was seen in 67% of revision patients with anterior/proximal misplacement in most cases. Severe trochlear dysplasia Dejour types C and D were seen in 36% of the patients compared to 30% of primary MPFL-R patients (NS). The mean Kujala Anterior Knee Pain Scale score at final follow-up was 61.7 (SD 18.8) compared to 80.3 (SD 18) in primary MPFL-R patients (P < 0.01). The mean pain score at rest was 2.3 (SD 2.5) for revision MPFL-R patients compared to 1.7 (SD 2.5) in primary MPFL-R patients (NS) and their mean pain score during activity was 5.0 (SD 3.2) compared to 1.3 (SD 2.2) in primary MPFL patients (P < 0.001).

CONCLUSION

Although revision MPFL-R establishes acceptable patellar stability, the subjective outcomes after revision MPFL-R do not improve significantly, and are poorer than after primary MPFL-R. Non-anatomical graft position can be an important cause of MPFL-R failure. The clinical relevance of this study is that it shows that it may be difficult to improve self-reported outcomes in revision MPFL-R patients.

LEVEL OF EVIDENCE

III.

Medial patellotibial ligament and medial patellomeniscal ligament: anatomy, imaging, biomechanics, and clinical review

PURPOSE

The purpose of this article is to review anatomical, biomechanical, and clinical data of the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML), as well as studies focusing on the medial patellofemoral ligament (MPFL) but with relevant data about the MPTL and MPML.

METHODS

A literature search of articles specifically addressing the MPTL and/or MPML was included along with studies focusing on the MPFL but with relevant data about the MPTL and MPML.

RESULTS

The medial patellar ligaments responsible for maintaining the stability of the patellofemoral (PF) joint include the MPFL, the MPTL, and the MPML. The MPFL is considered the primary restraint to lateral patellar translation, while the latter two are considered secondary restraints. There is robust literature on the anatomical, imaging, and biomechanical characteristics of the MPFL, and also the clinical outcome of its injury and surgical reconstruction; much less is known about the MPTL and MPML. Isolated MPFL reconstruction has good clinical and functional outcomes, with a low failure rate when defined as frank re-dislocation. Complications, including continued episodes of patellar apprehension and subluxation, remain present in most series. In addition, the current literature primarily includes a homogeneous population with few excessive anatomic dysplastic factors. There is lack of knowledge on the role of MPTL and MPML in (potentially) aiding patella stabilization and improving clinical outcomes. Understanding the role of the medial-sided patellar ligaments, in particular the role of the secondary stabilizers, in PF function and injury will aid in this goal.

CONCLUSION

MPTL and MPML have consistent basic science literature, as well as favorable clinical outcomes of surgical patellar stabilization with reconstruction of the MPTL. However, there is much heterogeneity among clinical case series and lack of comparative studies to allow clear indication for the role of isolated or combined surgical reconstruction in patellar stabilization. Therefore, this comprehensive review helps understand the current knowledge and the possible applications in the orthopedic clinical practice.

LEVEL OF EVIDENCE

V.

Distal Femoral Valgus and Recurrent Traumatic Patellar Instability: Is an Isolated Varus Producing Distal Femoral Osteotomy a Treatment Option?

BACKGROUND

Genu valgum, a risk factor for recurrent patellofemoral instability, can be addressed with a varus producing distal femoral osteotomy (DFO). The purpose of this study is to report 3-year clinical and radiographic outcomes on a series of skeletally mature adolescents with traumatic patellofemoral instability and genu valgum who underwent a varus producing DFO.

METHODS

Consecutive patients (n=11) who underwent an isolated DFO for recurrent traumatic patellar instability over a 4-year study period (2009 to 2012) were reviewed. All patients were below 19 years of age, skeletally mature, had ≥2 patellar dislocations, genu valgum (≥ zone II mechanical axis) and failed nonoperative treatment. Exclusion criteria included less than three-year follow-up, congenital or habitual patellar instability, osteotomy indicated for pathology other than patellar instability, or biplanar osteotomies. Demographic, clinical, and radiographic data were retrospectively analyzed. Recurrence of instability and outcome measures (Kujala and Tegner Activity Scale) were collected at final followed-up prospectively.

RESULTS

Ten of 11 patients (average age, 16 y; range, 14 to 18 y; 4 male individuals: 7 female individuals) with an average follow-up of 4.25 years (range, 3.2 to 6.0 y) met inclusion criteria. The average body mass index (BMI) of all patients was 31.3 (range, 19.7 to 46.8) with 91% considered overweight (BMI>25) and 55% obese (BMI>30). The average preoperative lateral distal femoral angle was 75.4 degrees with an average correction of 10.4 degrees (range, 7 to 12 degrees) (P<0.001). Mean patellar height ratios were reduced; with Caton-Deschamps Index significantly reduced to 1.08 (range, 0.86 to 1.30) (P<0.005). The average postoperative Kujala score was 83.6 (range, 49 to 99) with 7 subjects (70%) reporting good to excellent function (Kujala > 80) and 8 (80%) having no further episodes of instability. The mean postoperative Tegner activity score was 5.5 (range, 3 to 7).

CONCLUSIONS

A distal femoral varus producing osteotomy may change radiographic parameters associated with patellar instability and improve clinical outcomes by reducing symptomatic patellofemoral instability in this patient population.

LEVEL OF EVIDENCE

Level IV.

Quantitative and Qualitative Analysis of the Medial Patellar Ligaments: An Anatomic and Radiographic Study

BACKGROUND

The qualitative and quantitative anatomy of the medial patellar stabilizers has been reported; however, a quantitative analysis of the anatomic and radiographic attachments of all 4 ligaments relative to anatomic and osseous landmarks, as well as to one another, has yet to be performed.

PURPOSE

To perform a qualitative and quantitative anatomic and radiographic evaluation of the medial patellofemoral ligament (MPFL), medial patellotibial ligament (MPTL), medial patellomeniscal ligament (MPML), and medial quadriceps tendon femoral ligament (MQTFL) attachment sites, with attention to their relationship to pertinent osseous and soft tissue landmarks.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Ten nonpaired fresh-frozen human cadaveric knees were dissected, and the MPFL, MPTL, MPML, and MQTFL were identified. A coordinate measuring device quantified the attachment areas of each structure and its relationship to pertinent bony landmarks. Radiographic analysis was performed through ligament attachment sites and relevant anatomic structures to assess their locations relative to pertinent bony landmarks.

RESULTS

Four separate medial patellar ligaments were identified in all specimens. The center of the MPFL attachments was 14.3 mm proximal and 2.1 mm posterior to the medial epicondyle and 8.3 mm distal and 2.7 mm anterior to the adductor tubercle on the femur and 8.9 mm distal and 19.9 mm medial to the superior pole on the patella. The MQTFL had a mean insertion length of 29.3 mm on the medial aspect of the distal quadriceps tendon. The MPTL and MPML shared a common patellar insertion and were 9.1 mm proximal and 15.4 mm medial to the inferior pole. The MPTL attachment inserted on a newly identified bony ridge, which was located 5.0 mm distal to the joint line. The orientation angles of the MPTL and MPML with respect to the patellar tendon were 8.3° and 22.7°, respectively.

CONCLUSION

The most important findings of this study were the correlative anatomy of 4 distinct medial patellar ligaments (MPFL, MPTL, MPML, MQTFL), as well as the identification of a bony ridge on the medial proximal tibia that consistently served as the attachment site for the MPTL. The quantitative and radiographic measurements, while comparable with current literature, detailed the meniscal insertion of the MPML and defined a patellar insertion of the MPTL and the MPML as a single attachment. The data allow for reproducible landmarks to be established from previously known bony and soft tissue structures.

CLINICAL RELEVANCE

The findings of this study provide the anatomic foundation needed for an improved understanding of the role of medial-sided patellar restraints. This will help to further refine injury patterns and/or soft tissue deficiencies that result in lateral patellar instability, which can then be addressed with an anatomic-based reconstruction or repair technique and potentially lead to improved outcomes.

Origin and insertion of the medial patellofemoral ligament: a systematic review of anatomy

PURPOSE

The medial patellofemoral ligament (MPFL) is the major medial soft-tissue stabiliser of the patella, originating from the medial femoral condyle and inserting onto the medial patella. The exact position reported in the literature varies. Understanding the true anatomical origin and insertion of the MPFL is critical to successful reconstruction. The purpose of this systematic review was to determine these locations.

METHODS

A systematic search of published (AMED, CINAHL, MEDLINE, EMBASE, PubMed and Cochrane Library) and unpublished literature databases was conducted from their inception to the 3 February 2016. All papers investigating the anatomy of the MPFL were eligible. Methodological quality was assessed using a modified CASP tool. A narrative analysis approach was adopted to synthesise the findings.

RESULTS

After screening and review of 2045 papers, a total of 67 studies investigating the relevant anatomy were included. From this, the origin appears to be from an area rather than (as previously reported) a single point on the medial femoral condyle. The weighted average length was 56 mm with an 'hourglass' shape, fanning out at both ligament ends.

CONCLUSION

The MPFL is an hourglass-shaped structure running from a triangular space between the adductor tubercle, medial femoral epicondyle and gastrocnemius tubercle and inserts onto the superomedial aspect of the patella. Awareness of anatomy is critical for assessment, anatomical repair and successful surgical patellar stabilisation.

LEVEL OF EVIDENCE

Systematic review of anatomical dissections and imaging studies, Level IV.

Treatment of Primary Acute Patellar Dislocation: Systematic Review and Quantitative Synthesis of the Literature

PURPOSE

The aim of this study was to evaluate clinical outcomes, rate of redislocation, and complications after conservative or surgical procedures used to treat primary acute patellar dislocation.

METHODS

A comprehensive search of PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases using various combinations of the keywords "patella," "dislocation," "treatment," "acute," "primary" was performed. The following data were extracted: demographics, chondral defects and soft tissue lesions, outcome measurements, type of management, recurrence of instability, and complications.

RESULTS

A total of 2134 knees in 2086 patients were included, with an average age at dislocation of 20.3 years. The average Kujula score was 75.6 for patients treated conservatively and 88.7 for patients undergoing surgical treatment in the short-medium follow-up (less than 5 years); the average Kujula score was 87.5 for patients treated conservatively and 86.6 for patients undergoing surgical treatment in the long-term follow-up (more than 5 years). The rate of recurrence was significantly lower in the surgical group (25%) than in the conservative group (36.4%). The overall complication rate was 6.5% (29 of 441 knees) in the surgical management group. No complications were reported for patients treated conservatively.

CONCLUSIONS

Surgical treatment of primary acute patellar dislocation leads to significantly lower rate of redislocation and provides better short-medium clinical outcomes, whereas in the long-term follow-up, results of patients treated conservatively were as good as those of surgical patients. Further randomized controlled trials, describing anatomical abnormalities and soft-tissue integrity that may influence the choice of treatment, are needed.

LEVEL OF EVIDENCE

Systematic review, level IV.

The contribution of the tibial tubercle to patellar instability: analysis of tibial tubercle-trochlear groove (TT-TG) and tibial tubercle-posterior cruciate ligament (TT-PCL) distances

PURPOSE

The purpose of this study is to assess the reliability of measuring the tibial tubercle to posterior cruciate (TT-PCL) distance compared to the tibial tubercle to trochlear groove (TT-TG) distance on magnetic resonance imaging (MRI), establish baseline TT-PCL values in patellar instability patients, and determine the predictive value of an excessive TT-PCL distance (≥24 mm) for recurrent patellar instability compared to a TT-TG distance ≥20 mm.

METHODS

TT-TG and TT-PCL distances were calculated on MRI in a randomized and blinded fashion by two reviewers on 54 patients (59 knees) with patellar instability. Interobserver reliability was assessed using interclass correlation coefficients (ICC). TT-PCL distances were also assessed to establish mean values in patellar instability patients. The ability of excessive TT-PCL and TT-TG distances to predict recurrent instability was assessed by comparing odds ratios, sensitivities, and specificities.

RESULTS

Interobserver reliability was excellent for both TT-TG (ICC = 0.978) and TT-PCL (ICC = 0.932). The mean TT-PCL in these 59 knees was 21.7 mm (standard deviation 4.1 mm). Twelve (20 %) of 59 knees had a single dislocation, and 47 (80 %) exhibited 2 or more dislocations. The odds ratios, sensitivities, and specificities of a TT-TG distance ≥20 mm for identifying patients with recurrent dislocation were 5.38, 0.213, and 1.0, respectively, while those of a TT-PCL distance ≥24 mm were 1.46, 0.298, and 0.583, respectively. Of the 10 knees with a TT-TG distance ≥20 mm, all 10 (100 %) had recurrent instability, while 14 (73.7 %) of the 19 knees with a TT-PCL ≥24 mm experienced multiple dislocations (n.s.).

CONCLUSION

Both TT-PCL and TT-TG can be measured on MRI with excellent interobserver reliability. In this series, the mean TT-PCL value in patients with patellar instability was 21.8 mm, but the range was broad. A TT-PCL distance ≥24 mm was found to be less predictive of recurrent instability in this series. For patients experiencing multiple episodes of patellar instability in the setting of a normal TT-TG distance, obtaining the TT-PCL measurement may provide a more focused assessment of the tibial contribution to tubercle lateralization.

LEVEL OF EVIDENCE

III.

Femoral articular geometry and patellofemoral stability

BACKGROUND

Patellofemoral instability is a major cause of anterior knee pain. The aim of this study was to examine how the medial and lateral stability of the patellofemoral joint in the normal knee changes with knee flexion and measure its relationship to differences in femoral trochlear geometry.

METHODS

Twelve fresh-frozen cadaveric knees were used. Five components of the quadriceps and the iliotibial band were loaded physiologically with 175N and 30N, respectively. The force required to displace the patella 10mm laterally and medially at 0°, 20°, 30°, 60° and 90° knee flexion was measured. Patellofemoral contact points at these knee flexion angles were marked. The trochlea cartilage geometry at these flexion angles was visualized by Computed Tomography imaging of the femora in air with no overlying tissue. The sulcus, medial and lateral facet angles were measured. The facet angles were measured relative to the posterior condylar datum.

RESULTS

The lateral facet slope decreased progressively with flexion from 23°±3° (mean±S.D.) at 0° to 17±5° at 90°. While the medial facet angle increased progressively from 8°±8° to 36°±9° between 0° and 90°. Patellar lateral stability varied from 96±22N at 0°, to 77±23N at 20°, then to 101±27N at 90° knee flexion. Medial stability varied from 74±20N at 0° to 170±21N at 90°. There were significant correlations between the sulcus angle and the medial facet angle with medial stability (r=0.78, p<0.0001).

CONCLUSIONS

These results provide objective evidence relating the changes of femoral profile geometry with knee flexion to patellofemoral stability.

I.S.Mu.L.T. first-time patellar dislocation guidelines

Primary traumatic patellar dislocation is common, particularly in young active individuals. A consensus on its management is still lacking. The present work provides easily accessible guidelines to be considered as recommendations for a good clinical practice developed through a process of systematic review of the literature and expert opinion, to improve the quality of care and rationalize the use of resources.

LEVEL OF EVIDENCE

Ia.

Traumatic Patellar Dislocation and Cartilage Injury: A Follow-up Study of Long-Term Cartilage Deterioration

BACKGROUND

Patellofemoral cartilage deterioration and osteoarthritis are reported to be associated with recurrent patellar dislocation. However, the association between first-time traumatic patellar dislocation and cartilage deterioration is unknown.

PURPOSE

The aim of this study was to assess long-term cartilage deterioration in the patellofemoral and tibiofemoral joint after conservatively treated traumatic lateral patellar dislocation.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Twenty patients (mean age, 25 years) who sustained first-time traumatic lateral patellar dislocation with no previous patellofemoral instability symptoms were initially scanned with 1.5-T magnetic resonance imaging (MRI). A follow-up 3-T MRI was conducted, on average, 8 years after first-time lateral patellar dislocation. Subjective instability symptoms and Knee injury and Osteoarthritis Outcome Score were also assessed.

RESULTS

In the primary MRI, patellofemoral cartilage injury was seen in 14 of 20 patients (70%). Most (14/15) of the injuries were seen in the patellar cartilage, especially at the medial facet. On the follow-up MRI, patellofemoral cartilage deterioration was visible for all patients. The central patella ( P = .005) seemed especially prone to cartilage deterioration during the follow-up. Half of the patients (10/20) had grade 3-4 cartilage lesions in the patellofemoral joint in the follow-up MRI. In the primary MRI, only 1 patient exhibited tibiofemoral joint cartilage lesions, whereas at the time of follow-up, 10 of 20 patients exhibited tibiofemoral cartilage lesions. The majority of these lesions were considered clinically nonsignificant (International Cartilage Repair Society = 1) and were seen in the lateral compartment (6/10, 60%). Of the 14 patients (36%) with injury to the patellar cartilage, 5 reported subsequent instability of the patellofemoral joint, but this was not associated with more significant cartilage deterioration in the follow-up MRI compared with patients without redislocation.

CONCLUSION

While recurrent lateral patellar dislocation is known to lead to degenerative process, a single first-time or infrequently recurring traumatic lateral patellar dislocation also seems to be associated with gradual cartilage deterioration. Traumatic lateral patellar dislocation might initiate gradual degeneration of the cartilage in the patellofemoral joint and can lead to the development of generalized knee osteoarthritis. Instability symptoms of the patellofemoral joint, however, were not related to the severity of the deterioration.

Predictors of Recurrent Patellar Instability in Children and Adolescents After First-time Dislocation

BACKGROUND

Patellar dislocations are one of the most common knee injuries in children and adolescents and are challenging to treat. Recurrence rates are relatively high and many patients have functional limitations, even in the absence of a recurrent instability episode. The purpose of this study was to examine the risk factors in patients with first-time patellofemoral dislocations to develop a prediction model of recurrence.

METHODS

A single institution retrospective review of all patients with a first-time patellofemoral dislocation from 2002 to 2013 was performed. Demographic risk factors (age, sex, laterality, mechanism of injury, and history of contralateral patellar dislocation) and radiographic risk factors (increased patella height, trochlear dysplasia, and skeletal immaturity) were examined. Patella height was measured using Caton-Deschamps index (CDI). Trochlear dysplasia was assessed using the 2-grade Dejour classification and skeletal immaturity was assessed based on the distal femur and proximal tibia physis (open, closing, or closed).

RESULTS

In total, 266 knees in 250 patients were included in the study. Of these, 222 (83.5%) were treated nonoperatively and 44 (16.5%) were treated surgically. Of the knees treated nonoperatively, 77 (34.7%) had a recurrence. Significant risk factors for recurrence on univariate analysis were age 14 years and below, history of contralateral patellar dislocation, trochlear dysplasia, skeletal immaturity, and a CDI>1.45. Multivariate analysis was performed and trochlear dysplasia and skeletal immaturity were the most significant factors with odds ratios of 3.56 and 2.23, respectively. The presence of all 4 multivariate risk factors (CDI>1.45, history of contralateral patellar dislocation, trochlear dysplasia, and skeletal immaturity) had a predicted risk of recurrence of 88%. The presence of any 3 risk factors had a predicted risk of about 75% and the presence of any 2 risk factors had a predicted risk of about 55%.

CONCLUSIONS

Trochlear dysplasia, skeletal immaturity, CDI>1.45, and a history of contralateral patellar dislocation were all significant risk factors for recurrence in patients with first-time patellar dislocations. A predictive model for calculation of recurrence risk was developed for any combination of the different risk factors. This information is useful when counseling patients and their families after first-time patellar dislocation about prognosis and potential outcomes.

LEVEL OF EVIDENCE

Level IV-retrospective case series.

Current Concepts in the Management of Patellar Instability

Patellar instability is a common presenting clinical entity in the field of orthopedics. This not only can occur from baseline morphologic variability within the patellofemoral articulation and alignment, but also from traumatic injury. While conservative management is many times employed early in the treatment course, symptomatic patellar instability can persist. This article reviews the available indexed published literature regarding patellar instability. Given the debilitating nature of this condition and the long term sequelae that can evolve from its lack of adequate recognition and treatment, this article details the most current methods in the evaluation of this entity as well as reviews the most up-to-date surgical treatment regimens that are available to address this condition.

Medial patellofemoral ligament reconstruction using a bone groove and a suture anchor at patellar: a safe and firm fixation technique and 3-year follow-up study

Background

Graft fixation is critical to the restoration of the medial patella of femoral ligament function and long-term success. Numerous fixations at the patella have been described, while the complications including patellar fractures, violation of the posterior patella and delay of tendon-to-bone healing remain significant challenges. Here, we describe a safe and firm fixation at the patellar for medial patellofemoral ligament (MPFL) reconstruction and explore the safety angle of drilling the suture anchor at different morphology of the patellar. Moreover, we evaluate the results at a 3-year follow-up.

Methods

Combined bone groove and suture anchor fixation at the patella was performed on 26 patients (16 females, 10 males; mean age 26.3 ± 4.7 years) diagnosed with recurrent patellar dislocation. The drilling direction of the suture anchor referred to the safety angle according to the Wiberg type classification. The safety angle was defined as the angle between the drill tunnel and a line that connected the medial and lateral margins of the patella and was established following computed tomography assessment of 117 patients who were diagnosed with patellar dislocation in our hospital according to the Wiberg type classification (I:29, II:65, III:23). X-ray, Lysholm, Kujala and Tegner scores were obtained preoperatively and at the time of final follow-up.

Results

There were no patellar complications, including fracture and redislocation. Average congruence, patella tilt angles and lateral patella angle were significantly changed (P < 0.01). The Lysholm, Kujala and Tegner scores were significantly increased (P < 0.01). The safe angles of male and female patients according to the patellar Wiberg type classification were less than 45.32 ± 1.76 and 41.20 ± 1.33, 69.74 ± 1.38 and 63.66 ± 1.45 and 84.11 ± 1.67 and 80.26 ± 1.73, respectively.

Conclusions

We achieved encouraging results with this fixation at the patellar. When drilling from Wiberg type I to type III patellar, the suture anchor should be more vertical. When fixing the patellar of female patients, the drilling suture anchor should be more sloping.

Adolescent Patella Instability Extensor Mechanics: Insall Extensor Realignment Versus Medial Patellofemoral Ligament Reconstruction

BACKGROUND

A plethora of surgical procedures have been promoted in the literature regarding the treatment of patella instability in the adolescent population; yet, none have compared the joint reaction forces of knee extensor mechanics after extensor mechanism realignment (Insall) or medial patellofemoral ligament reconstruction (MPFLR). The purpose of this study was to determine if there was a difference in knee extensor mechanics between these techniques.

METHODS

Three cohorts of 10 age-matched adolescents (normal control, Insall, and MPFLR) were compared using preoperative magnetic resonance imaging and postoperative x-ray in the 2 surgical groups. Patella and patella tendon length were measured and the actual moment arm calculated. Compression angles were estimated and the effective moment arms determined. Patellofemoral and quadriceps joint reaction forces were calculated. Comparisons within and between the 3 groups were determined and the dependent variables analyzed for statistical differences.

RESULTS

Mean ages (15.6±2.2 y), preoperative measures and dependent variables were not different between the groups (P>0.05). Postoperatively, there was a significant difference for the patellofemoral joint reaction force with respect to the quadriceps force (Fr/Fq), being larger within the Insall group (1.08±0.08) than the MPFLR group (0.92±0.09) (P<0.001). The postoperative MPFLR group variables were not significantly different to the control group. In contrast, the postoperative Insall group yielded larger joint reaction forces compared with control (1.08±0.08 vs. 0.83±0.11, P<0.001), as well as different effective moment arms, Insall versus control (51.23±8.8 vs. 41.9±5.9, P<0.001).

CONCLUSIONS

Not all surgical interventions for recurrent patella instability affect knee mechanics similarly. Although an extensor realignment procedure may still have indications in children, the treating surgeon should be aware that it does not appear to restore normal joint mechanics.

CLINICAL RELEVANCE

The Insall-type procedure may increase the patellofemoral joint reaction forces beyond normal without fully restoring the effective moment arms; whereas, MPFL reconstruction appears to restore the effective moment arm without excessive joint reaction forces.

Patella dislocations

The patellofemoral joint relies on muscular, ligamentous and bony support for normal stability and function. Dislocations commonly occur due to simultaneous rotational force with contraction of the quadriceps. Bony, muscular and ligamentous factors predispose to dislocations although no single factor causes more dislocations than any other. The diagnosis is based on the history combined with physical examination and radiological investigations. A careful scrutiny of the radiographs is necessary to determine the presence of osteochondral fractures in acute patellar dislocations. Special views and further imagining is indicated especially in those with recurrent symptoms. The treatment of acute dislocations is most commonly non operative. Surgery in acute patellar dislocations is indicated for intra articular fragments or those with large osteochondral fractures. Various soft tissue and bony realignment procedures have been described for recurrent dislocations. No single procedure is superior to another. Factors such as the patient’s age, functional needs, extent of malalignment and the condition of the joint are important factors to be considered prior to operative intervention. In this paper we discuss an overview of the diagnosis and management of patella dislocations with a literature review on the current concepts in treatment.

Operative Management of Patellar Instability in the United States: An Evaluation of National Practice Patterns, Surgical Trends, and Complications

Background:

Treatment of patellofemoral instability has evolved as our understanding of the relevant pathoanatomy has improved. In light of these developments, current practice patterns and management trends have likely changed to reflect these advancements; however, this has not been evaluated in a formal study.

Purpose:

To determine nationwide patient demographics, surgical trends, and postoperative complications associated with the operative management of patellar instability surgery.

Study Design:

Descriptive epidemiological study.

Methods:

A large private-payer database (PearlDiver) comprising patients covered by Humana and United Healthcare insurance policies was retrospectively reviewed using Current Procedural Terminology (CPT) codes to identify patients who underwent surgery for patellar instability. The study cohort was established by querying for patients billed under CPT codes 27420, 27422, or 27427 while satisfying the diagnostic requirement of patellar instability (International Classification of Diseases–9th Revision codes 718.36, 718.86, or 836.3). Patient demographics, surgical trends, concomitant procedures, and postoperative complications were determined.

Results:

A total of 6190 patients underwent surgical management for patellar instability. Adolescents (age range, 10-19 years) represented 51.5% of cases, and 59.6% were female. The number of patellar instability procedures increased annually over the study period in both the Humana (P = .004, R² = 0.76) and United Healthcare (P = .097, R² = 0.54) cohorts. The most common concomitant procedures were lateral retinacular release (43.7%), chondroplasty (31.1%), tibial tubercle osteotomy (13.1%), removal of loose bodies (10.5%), osteochondral grafting (9.5%), and microfracture surgery (9.5%). Manipulation under anesthesia was required in 4.6% of patients within 1 year. Patellar fracture within 1 year and infection within 30 days occurred in 2.1% and 1.2% of patients, respectively.

Conclusion:

Patellar instability surgery has increased over the past decade. This finding may be attributed to growing clinical evidence to support these procedures as well as increased surgeon familiarity and comfort with these specific techniques. We observed an unexpectedly high rate of concomitant lateral retinacular release. Overall, the rates of commonly recognized complications (stiffness, patellar fracture, and postoperative infection) were similar to those observed in smaller case series.

The Efficacy of Medial Patellofemoral Ligament Reconstruction Combined with Tibial Tuberosity Transfer in the Treatment of Patellofemoral Instability

A systematic review of the literature was undertaken to evaluate the efficacy of medial patellofemoral ligament (MPFL) reconstruction combined with tibial tuberosity transfer (TTT) in the treatment of patellofemoral instability. Using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, a systematic search was carried out to identify and review the published literature pertinent to MFPL reconstruction combined with TTT. Relevant studies were critically appraised with narrative data synthesis. Studies that met the eligibility criteria were suitable for appraisal and consisted of case series and therapeutic series (levels IV & III). All studies had inherent variations in outcomes reporting and limited follow-up. Combined treatment offers restoration of normal anatomy, thus adding clinical value to the currently recommended anatomic approach to MPFL reconstruction. Nevertheless, the current body of evidence does not determine the threshold at which patellofemoral axis requires the need for adjunctive distal realignment as opposed to MPFL reconstruction alone. This review highlighted numerous recurring limitations in the conduct and presentation of the studies, which inadvertently mitigated the interpretation of their results. Future priority should be awarded to larger randomised controlled trials utilising validated patient reported outcome measures.

An Algorithmic Approach to the Management of Recurrent Lateral Patellar Dislocation

High-level evidence supports nonoperative treatment for first-time lateral acute patellar dislocations. Surgical intervention is often indicated for recurrent dislocations. Recurrent instability is often multifactorial and can be the result of a combination of coronal limb malalignment, patella alta, malrotation secondary to internal femoral or external tibial torsion, a dysplastic trochlea, or disrupted and weakened medial soft tissue, including the medial patellofemoral ligament (MPFL) and the vastus medialis obliquus. MPFL reconstruction requires precise graft placement for restoration of anatomy and minimal graft tension. MPFL reconstruction is safe to perform in skeletally immature patients and in revision surgical settings. Distal realignment procedures should be implemented in recurrent instability associated with patella alta, increased tibial tubercle-trochlear groove distances, and lateral and distal patellar chondrosis. Groove-deepening trochleoplasty for Dejour type-B and type-D dysplasia or a lateral elevation or proximal recession trochleoplasty for Dejour type-C dysplasia may be a component of the treatment algorithm; however, clinical outcome data are lacking. In addition, trochleoplasty is technically challenging and has a risk of substantial complications.

Minimally invasive medial patellofemoral ligament reconstruction for patellar instability using an artificial ligament: A two year follow-up

BACKGROUND

Recurrence of acute patellar dislocation affects approximately 30% of individuals, and up to 75% of those with grade IV instability. The medial patellofemoral ligament (MPFL) is considered to be critical for patellar stabilization. MPFL reconstruction with allografts has been proposed to reduce risk of recurrence, but there is limited evidence about the safety and effectiveness of techniques using synthetic allografts.

METHODS

We present a retrospective case series of 29 individuals who underwent a MPFL reconstruction between 2009 and 2012, using an artificial ligament for patellar instability by a single surgeon. Clinical, radiological and functional outcomes were measured at a minimum of 24 months.

RESULTS

31 knees (29 individuals) were followed up for a median of 43 (range: 24-68) months. Using the Crosby and Insall grading system, 21 (68%) were graded as excellent, nine (29%) were good, one (3%) as fair and none as worse at 24 months. The mean improvement in Lysholm knee score for knee instability was 68 points (standard deviation 10). Ligamentous laxity was seen in 17 (55%) of individuals. In this subset, 12 were graded as excellent, four as good and one as fair. The mean improvement in patellar height was 11% at three months follow-up. All knees had a stable graft fixation with one re-dislocation following trauma.

CONCLUSIONS

We propose a minimally invasive technique to reconstruct the MPFL using an artificial ligament allowing early mobilization without bracing. This study indicates the procedure is safe, with a low risk of re-dislocation in all grades of instability.

LEVEL OF EVIDENCE

Level IV Case Series.

Combined Reconstruction of the Medial Patellofemoral Ligament With Quadricipital Tendon and the Medial Patellotibial Ligament With Patellar Tendon

Although the medial patellotibial ligament (MPTL) has been neglected regarding its function in patellar stability, recently, its importance in terminal extension and during flexion has been recognized. Indications for reconstruction of the medial patellofemoral ligament combined with the MPTL are extension subluxation, flexion instability, children with anatomic risk factors for patellar instability, and knee hyperextension associated with generalized laxity. We describe a combined reconstruction of the medial patellofemoral ligament with quadricipital tendon and reconstruction of the MPTL with patellar tendon autografts.

Management of Acute Patellar Dislocation: A Case Report

OBJECTIVE

The purpose of this case study is to describe the evaluation and management of patellar dislocations and the different approaches used from providers in different countries.

CLINICAL FEATURES

An individual dislocated her left patella while traveling abroad and received subsequent care in Thailand, China, and the United States.

INTERVENTION AND OUTCOME

Nonoperative treatment protocols including manual closed reduction of the patella, casting of the leg, and rehabilitation exercises were employed.

CONCLUSION

Receipt of care when abroad can be challenging. The patient's knee range of motion and pain continued to improve when she was diligent about performing the home exercise program. This case highlights the importance of a thorough examination, a proper regimen of care, and patient counseling to ensure a full recovery and minimize the chance of re-injury.

Reconstruction of medial patellofemoral ligament using quadriceps tendon combined with reconstruction of medial patellotibial ligament using patellar tendon: initial experience

OBJECTIVE

To describe a surgical technique for anatomical reconstruction of the medial patellofemoral ligament using the quadriceps tendon, combined with reconstruction of the medial patellotibial ligament using the patellar tendon; and to present the initial results from a case series.

METHOD

The proposed technique was used on a series of cases of patients with diagnoses of patellofemoral instability and indications for surgical treatment, who were attended by the Knee Group of HC-IOT, University of São Paulo. The following were evaluated before and after the operation: range of motion (ROM), apprehension test, lateral translation test, patellar inclination test, inverted J sign, subluxation upon extension, pain from compression of the patella and pain from contraction of the quadriceps. After the operation, the patients were asked whether any new episode of dislocation had occurred, what their degree of satisfaction with the surgery was (on a scale from 0 to 10) and whether they would be prepared to go through this operation again.

RESULTS

Seven knees were operated, in seven patients, with a mean follow-up of 5.46 months (±2.07). Four patients who presented apprehension before the operation did not show this after the operation. The lateral translation test became normal for all the patients, while the patellar inclination test remained positive for two patients. The patients with an inverted J sign continued to be positive for this sign. Five patients were positive for subluxation upon extension before the operation, but all patients were negative for this after the operation. None of the patients presented any new episode of dislocation of the patella. All of them stated that they were satisfied: five gave a satisfaction score of 9 and two, a score of 10. All of them said that they would undergo the operation again. Only one patient presented a postoperative complication: dehiscence of the wound.

CONCLUSION

Reconstruction of the medial patellofemoral ligament using the quadriceps tendon, combined with reconstruction of the medial patellotibial ligament using the patellar tendon, was technically safe and presented good objective and subjective clinical results in this case series with a short follow-up.

Medial Patellofemoral Ligament Injuries in Children With First-Time Lateral Patellar Dislocations: A Magnetic Resonance Imaging and Arthroscopic Study

BACKGROUND

A lateral patellar dislocation (LPD) is the most common knee injury in children with traumatic knee hemarthrosis. The medial patellofemoral ligament (MPFL), the important passive stabilizer against LPDs, is injured in more than 90% of cases. The MPFL injury pattern is most often defined in adults or in mixed-age populations. The injury pattern in the skeletally immature patient may be different.

PURPOSE

To describe MPFL injuries in the skeletally immature patient by magnetic resonance imaging (MRI), and to compare the results with the injury pattern found at arthroscopic surgery.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This was a prospective series of patients aged 9 to 14 years with acute, first-time traumatic LPDs in whom clinical examinations, radiographs, MRI, and arthroscopic surgery were performed within 2 weeks from the index injury. The MPFL injury was divided into 3 different groups according to the location: patellar site, femoral site, or multifocal. The MPFL injury site was confirmed on MRI by soft tissue edema. The length of the MPFL injury at the patellar site was measured at arthroscopic surgery, and those ≥2 cm were defined as total ruptures.

RESULTS

A total of 74 patients (40 girls and 34 boys; mean age, 13.1 years) were included; 73 patients (99%) had an MPFL injury according to MRI and arthroscopic surgery. The MRI scans showed an isolated MPFL injury at the patellar attachment site in 44 of 74 patients (60%), a multifocal injury in 26 patients (35%), an injury at the femoral site in 3 patients (4%), and no injury in 1 patient (1%). Arthroscopic surgery disclosed an isolated MPFL injury at the patellar site in 60 of 74 patients (81%) and a multifocal injury in 13 patients (18%); the MPFL injury at the patellar site was a total rupture in 49 patients (66%). Edema at the patellar attachment site on MRI was proven to be an MPFL rupture at the same site at arthroscopic surgery in 99% of the patients. A patellar-based injury, isolated or as part of a multifocal injury, was present on MRI in 95% (n = 70) of the patients, with a false-negative rate of 5% (n = 4) of patients compared with arthroscopic surgery.

CONCLUSION

Skeletally immature children are more prone to sustaining an MPFL injury at the patellar attachment site. Arthroscopic surgery and MRI complement each other in the investigation of MPFL injuries.