Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients: A Systematic Review and Meta-analysis

Postoperative Access and Compliance Following Medial Patellofemoral Ligament Reconstruction in Hispanic Adolescents Mirrors the Non-Hispanic Adolescent Population

BACKGROUND

Disparity in surgical care of patellar instability patients has not been fully investigated in the adolescent Hispanic population. This demographic has been shown to have differences in their care, including a lower rate of surgical treatment for patellar instability. Socioeconomic factors have been cited as a factor that influences patient outcomes and its relationship with ethnicity in context of patellar instability has not been evaluated.

METHODS

Review performed of patients <19 years of age who underwent MPFL reconstruction between September 2008 and December 2015. Demographics, patient median household income data, and clinical variables were collected. Generalized linear mixed model (GLMM) with subject as random effects factor was utilized to evaluate differences between ethnicity groups due to nonindependence of data. It was then expanded to incorporate interactions between ethnicity and income.

RESULTS

Ninety-five patellar dislocation events met criteria in 85 adolescents (mean age: 15.5 y). Thirty-four (40%) adolescents identified as Hispanic. In univariate analysis no differences were found between Hispanic and non-Hispanic patients. The multivariate GLMM demonstrated a significant interaction between ethnicity and income. The Hispanic group in the >100% State median income category had the highest rate of postoperative clinic appointments attended (P=0.019). The Hispanic group in the <100% State median income category had the lowest rate of physical therapy appointments attended (P=0.044). No differences were observed for duration of follow-up (P=0.57) or final Kujala score (P=0.75).

CONCLUSIONS

Hispanic ethnicity alone is not associated with inferior postoperative management after MPFL reconstruction in adolescents. However, when socioeconomic status is considered, Hispanic patients of lower-income backgrounds are found to have lower compliance with postoperative rehab recommendations.

LEVEL OF EVIDENCE

Level III.

Outcomes of an All-Soft Tissue Fixation Technique for Reconstruction of the Medial Patellofemoral Complex Using Double-Bundle Quadriceps Tendon Autograft for Recurrent Patellar Dislocation in Skeletally Immature Patients

Background

Patellar fracture, femoral physis injury, and recurrent instability are concerning complications in medial patellofemoral ligament (MPFL) reconstruction (MPFLR) techniques for recurrent patellar dislocation in children and adolescents.

Purpose

To evaluate the outcomes of an anatomic all-soft tissue fixation technique for reconstruction of the medial patellofemoral complex (MPFC) using a double-bundle quadriceps tendon (QT) autograft for recurrent patellar dislocation in skeletally immature patients.

Study Design

Case series; Level of evidence, 4.

Methods

This retrospective study involved 24 skeletally immature patients (24 knees; 16 women and 8 men; age range, 9.5-15 years) with recurrent patellar dislocation who underwent MPFC reconstruction using a double-bundle QT autograft between September 2018 and January 2021. Only soft tissue suture fixation was used on the femoral and patellar sides of the 2 bundles of the QT. Radiographs, computed tomography, and magnetic resonance imaging were used to evaluate physeal status, lower limb alignment, patellar height and tilt, trochlear morphology, tibial tubercle-trochlear groove distance, and any associated knee pathology. Functional outcomes were assessed with the Kujala score, the visual analog scale (VAS) for pain, and the grading system of Insall et al.22.

Results

The mean follow-up time was 40 ± 9.6 months (range, 28-56 months). At the final follow-up, the Kujala and VAS pain scores showed a significant improvement versus preoperative scores (P < .001), and the passive lateral patellar glide showed a significant reduction (P < .001). All patients had negative apprehension and J signs. Of the 24 patients, 23 regained full range of motion, while 1 patient had a knee flexion deficit. The patellar tilt angle improved significantly at the final follow-up (P < .001). There was no patellar fracture, femoral physis injury, or recurrence of patellar dislocation. According to the grading system of Insall et al, the results were excellent in 15 knees (62.5%), good in 8 knees (33.3%), fair in 1 knee (4.2%), and no knees showed poor results.

Conclusion

Reconstruction of the MPFC using a double-bundle QT autograft with an all-soft tissue fixation technique was an effective method for treating patellar instability in skeletally immature patients.

Midterm Outcomes of Isolated Medial Patellofemoral Ligament Reconstruction for Patellar Instability in Ehlers-Danlos Syndrome

Background

Patellar instability is frequently encountered in patients with Ehlers-Danlos syndrome (EDS). The clinical outcomes of isolated medial patellofemoral ligament reconstruction (MPFLR) for patellar instability in patients with EDS are unknown.

Purpose

To evaluate midterm clinical outcomes of isolated MPFLR for patellar instability in patients with EDS and factors affecting these outcomes.

Study Design

Case series; Level of evidence, 4.

Methods

In a retrospective study, 31 patients (n = 47 knees) with EDS and patellar instability who underwent isolated MPFLR for recurrent patellar instability between 2008 and 2017 and had a minimum 2-year follow-up were identified. Preoperative radiographic images were measured for anatomic risk factors. Clinical outcomes-including postoperative complications-were evaluated. Factors associated with MPFLR failure were identified. Postoperative patient-reported outcomes (PROs)-including the pediatric version of the International Knee Documentation Committee, the Kujala score, the Hospital for Special Surgery Pediatric Functional Activity Brief Scale, the Banff Patellofemoral Instability Instrument 2.0, and the Knee injury and Osteoarthritis Outcome Score-were collected, and factors affecting PRO scores were analyzed.

Results

The mean age of the cohort was 14.9 ± 2 years. At a mean follow-up of 7.2 years, 18 of 47 (38.3%) knees required reoperations, of which 9 of 47 (19.1%) knees required revision stabilization for recurrent patellar instability. Also, 7 of 31 knees (22.6%) with autografts failed compared with 2 of 16 (12.5%) with allografts (P = .69). For autografts, 6 of 17 (35.3%) failures occurred with gracilis, but 0 of 13 (0%) occurred with semitendinosus (P = .02). Compared with patients without failures, patients with failed primary MPFLR were significantly younger (P = .0005) and were able to touch the palm to the floor with their knees extended (P = .03). For radiographic parameters, the patellar height and tilt were significantly higher in the failure group. The postoperative PROs were suboptimal at a mean follow-up of 5.2 years. All but 1 patient were satisfied with the final outcome.

Conclusion

At the midterm follow-up, 38.3% of patients with EDS required further surgery after isolated MPFLR for patellar instability; half of these revisions (19.1%) were to address recurrent instability. Recurrent instability after isolated MPFLR was more likely in younger patients and those who could touch the palm to the floor with their knees extended. Postoperative PROs were inferior; nonetheless, patient satisfaction was high.

Medial Patellofemoral Ligament Reconstruction With or Without Tibial Tubercle Osteotomy in Carefully Selected Patients Results in a 5% Revision Rate: A Preliminary Analysis

PURPOSE

The purpose was to assess the outcomes of medial patellofemoral ligament (MPFL) allograft reconstruction with or without tibial tubercle osteotomy (TTO) in adolescents, with a focus on evaluating demographic and imaging characteristics on outcomes.

METHODS

A single-institution retrospective study was performed of patients ages 12 to 19 years who underwent MPFL reconstruction +/- TTO for the treatment of lateral patellar instability. Demographic, clinical, surgical, and postoperative information was collected. All x-ray and magnetic resonance imaging measurements were completed independently by 2 surgeons. Patients were contacted to complete patient-reported outcomes at a minimum of 2 years following surgery. The primary outcome measure was recurrent instability resulting in revision surgery.

RESULTS

Seventy-eight knees in 74 patients, with a median age of 15.3 years (interquartile range: 14.4, 16.1), were included. Forty-five knees underwent isolated MPFL reconstruction and 33 knees had a combined MPFL + TTO. The knees that underwent MPFL + TTO had significantly greater tibial tubercle-trochlear groove distance (19.0 mm vs. 15.4 mm, P =0.015) and patellar tendon-lateral trochlear ridge distance (10.9 mm vs. 5.9 mm, P =0.018) than the knees treated with isolated MPFL reconstruction. Four knees (5.1%) underwent revision stabilization surgery, including 3 knees in the MPFL cohort (6.7%) and 1 knee in the MPFL + TTO cohort (3.0%). The rate of failure between the MPFL and MPFL + TTO knees was not significantly different, P =0.634. There were no differences in age, sex, body mass index, number of dislocations, or any imaging characteristics in patients who underwent revision versus those who did not. Patient-reported outcomes were collected on 50 knees at a median of 36 months (interquartile range: 24, 54) after surgery, and no differences were noted between cohorts.

CONCLUSIONS

Patellar stabilization surgery, including MPFL reconstruction and TTO in carefully selected patients, had excellent revision-free outcomes in 95% of this adolescent cohort. In this case series, those patients whose treatment included TTO had greater tibial tubercle-trochlear groove and patellar tendon-lateral trochlear ridge as compared to the isolated MPFL cohort. Despite previous literature suggesting demographic and imaging characteristics as risks for recurrent instability, we identified no characteristics within these two distinct surgical treatment groups to be predictive of the need for revision stabilization, regardless of the treatment group.

LEVEL OF EVIDENCE

Level III-retrospective comparison study.

Management of patellar instability in skeletally immature patients

Surgical intervention is the treatment of choice for recurrent lateral patellar instability. Surgery should be considered for first time lateral patella dislocations with osteochondral fractures or underlying anatomical risk factors. Primary repair and nonanatomical imbrications/reconstructions have fallen out of favor due to abnormal biomechanics and high rates of recurrence. Anatomical reconstruction of the MPFL using a variety of auto and allograft tissues have yielded good outcomes and low redislocation rates. Physeal sparing MPFL reconstruction techniques under radiological control are safe and do not cause growth disturbance. Allografts may be indicated for hyperlax patients. Although no clear cutoff points exist, correction of valgus and excessive femoral anteversion should be considered when indicated. Osteochondral and chondral injuries are common and should be addressed during surgery for instability.

A modified Delphi consensus statement on patellar instability: part I

Aims

The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach.

Methods

A total of 60 surgeons from 11 countries were invited to develop consensus statements based on their expertise in this area. They were assigned to one of seven working groups defined by subtopics of interest within patellar instability. Consensus was defined as achieving between 80% and 89% agreement, strong consensus was defined as between 90% and 99% agreement, and 100% agreement was considered to be unanimous.

Results

Of 27 questions and statements on patellar instability, three achieved unanimous consensus, 14 achieved strong consensus, five achieved consensus, and five did not achieve consensus.

Conclusion

The statements that reached unanimous consensus were that an assessment of physeal status is critical for paediatric patients with patellar instability. There was also unanimous consensus on early mobilization and resistance training following nonoperative management once there is no apprehension. The statements that did not achieve consensus were on the importance of immobilization of the knee, the use of orthobiologics in nonoperative management, the indications for MPFC repair, and whether a vastus medialis oblique advancement should be performed.

Concomitant Tibial Tubercle Osteotomy Reduces the Risk of Revision Surgery After Medial Patellofemoral Ligament Reconstruction for the Treatment of Patellar Instability

PURPOSE

To compare postoperative complication rates between patients who underwent medial patellofemoral ligament reconstruction (MPFLR) and those who underwent MPFLR with tibial tubercle osteotomy (TTO) in a large-scale study. A secondary goal was to investigate demographic associations with outcomes.

METHODS

Patients who underwent MPFLR (n = 3,480) or MPFLR-TTO (n = 615) for patellar instability were identified in the PearlDiver database. Rates of surgery for infection, procedures for knee stiffness, patellar fracture, and revision MPFLR within 2 years postoperatively were compared using multivariable logistic regression. Demographic associations with outcomes were also investigated.

RESULTS

The MPFLR-TTO cohort exhibited a significantly lower rate of revision surgery at 2 years (0.8% vs 1.9%; odds ratio [OR], 0.33; 95% confidence interval [CI], 0.10-0.80; P = .036) when compared with the MPFLR group. Independent of index procedure, patients younger than 21 years had significantly lower rates of requiring procedures for knee stiffness (OR, 0.35; 95% CI, 0.22-0.54; P < .001) and any complication at 2 years (OR, 0.59; 95% CI, 0.45-0.78; P < .001) when compared with older patients. Male patients displayed a significantly lower rate of requiring procedures for knee stiffness at 2 years than female patients (OR, 0.46; 95% CI, 0.25-0.78; P = .007). Tobacco use was associated with a significantly higher rate of postoperative infection at 2 years (OR, 2.35; 95% CI, 1.00-5.38; P = .046).

CONCLUSIONS

The MPFLR cohort exhibited higher rates of revision surgery at 2 years compared with the MPFLR-TTO cohort. Patient age under 21 years was associated with lower rates of any complication and requiring procedures for knee stiffness, male sex was associated with a lower rate of requiring procedures for knee stiffness, and tobacco use was associated with a higher rate of surgery for postoperative infection. This information can assist surgeons when counseling patients before these procedures are performed.

LEVEL OF EVIDENCE

Level III, retrospective, comparative prognostic trial.

The adductor magnus tendon is a viable option for medial patellofemoral ligament reconstruction, but with a busy surrounding neurovascular topography

PURPOSE

To describe the proximity of the neurovascular structures surrounding the adductor magnus (ADM), to delineate a safe boundary focusing on the techniques used during graft harvest and to evaluate whether the length of the ADM tendon is sufficient for safe medial patellofemoral ligament (MPFL) reconstruction.

METHODS

Sixteen formalin-fixed cadavers were dissected. The area surrounding the ADM, the adductor tubercle (AT) and the adductor hiatus was exposed. The following measurements were performed: the (1) total length of MPFL, (2) distance between the AT and the saphenous nerve, (3) the point where the saphenous nerve pierces the vasto-adductor membrane, (4) the point where the saphenous nerve crosses the ADM tendon, (5) the musculotendinous junction of the ADM tendon, and (6) the point where the vascular structures exit the adductor hiatus. Additionally, (7) the distance between the ADM musculotendinous junction and the nearest vessel (popliteal artery), (8) the distance between the ADM (at the level where the saphenous nerve crosses) and the nearest vessel, (9) the length between the AT and the superior medial genicular artery, and finally (10) the depth between the AT and the superior medial genicular artery were analyzed.

RESULTS

The in situ length of the native MPFL was 47.6 ± 42.2 mm. The saphenous nerve pierces the vasto-adductor membrane at a mean distance of 100 mm, although it crosses the ADM itself at an average of 67.6 mm. The vascular structures, on the other hand, become vulnerable at a distance of 89.1 ± 114.0 mm from the AT. After harvesting the ADM tendon, the mean length was found to be 46.9 mm, which was insufficient for fixation. Partial release from the AT resulted in a more adequate length for fixation (65.4 ± 88.7 mm).

CONCLUSION

The adductor magnus tendon is a viable option for the dynamic reconstruction of the MPFL. Knowledge of the surrounding busy neurovascular topography is paramount for a procedure typically performed in a minimally invasive way. The study results are clinically relevant, as they suggest that tendons should be shorter than the minimum distance from the nerve. If in some cases the length of the MPFL is longer than the distance of the ADM from the nerve, the results suggest that a partial dissection of the anatomical structures might be needed. Direct visualization of the harvesting region might be considered in such cases.

Interdisciplinary Orthopedic Management of Pediatric Patella Dislocation and Instability: An Educational Case Series

Pediatric patellar instability and/or dislocation is a challenging diagnosis category that requires an interdisciplinary team consisting of orthopedic surgeons and physical therapists for optimized patient outcomes. This educational case series outlines core concepts for three patients with unique patellar dislocation presentations. Case 1 is a 16-year-old male who presented with a history of five knee traumatic patellar dislocations with self-reduction and underwent knee arthroscopic surgery with debridement and microfracture of the patella chondral defect, arthroscopic lateral release to improve the patellar tilt, and medial patellofemoral ligament (MPFL) reconstruction. Case 2 is a 15-year-old female who presented with chronic knee pain and patella instability who underwent knee arthroscopic surgery with abrasion arthroplasty, microfracture of the patella, lateral release, tibial tubercle osteotomy medializing osteotomy, and MPFL reconstruction. Case 3 is a 14-year-old male who presented after a single episode of lateral patella dislocation and underwent open reduction and fixation of the lateral femoral condyle osteochondral fracture, a Grammont patellar medialization procedure, and MPFL reconstruction. All three patients received postoperative physical therapy (PT) to improve function and outcomes. These cases represent important concepts of patellar containment, risk factors for recurrent instability, associated pathology, and appropriate surgical care and postoperative rehabilitation. Furthermore, this case series highlights management decisions and pathways for three patients with different symptoms related to patellar instability, subsequent surgical correction, and postoperative physical therapy. Overall, interdisciplinary care of common pediatric orthopedic conditions can help improve patient outcomes and satisfaction. By understanding the biomechanics and decision-making surgical parameters regarding patellofemoral instability, clinicians can provide patients with better care.

Home ownership, full-time employment, and other markers of higher socioeconomic status are predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes among lateral patellar instability patients undergoing medial patellofemoral ligament reconstruction

BACKGROUND

The purpose of this study was to identify socioeconomic predictors of time to initial evaluation, time to surgery, and postoperative outcomes among lateral patellar instability patients undergoing medial patellofemoral ligament reconstruction (MPFLR).

METHODS

We conducted a retrospective review of patients at our institution who underwent primary MPFLR with allograft from 2011 to 2019 and had minimum 12-month follow-up. Patients were administered an email survey in January 2022 to assess symptom history, socioeconomic status, and postoperative outcomes including VAS satisfaction and Kujala score. Predictors of time to initial evaluation, time to surgery, and postoperative outcomes were identified using multivariable linear and logistic regression with stepwise selection.

RESULTS

Seventy patients were included in the cohort (mean age 24.8 years, 72.9% female, mean follow-up time 45.7 months). Mean time to evaluation was 6.4 months (range 0-221) and mean time to surgery was 73.6 months (range 0-444). Having a general health check-up in the year prior to surgery was predictive of shorter time to initial evaluation (β = - 100.5 [- 174.5, - 26.5], p = 0.008). Home ownership was predictive of shorter time to surgery (β = - 56.5 [- 104.7, 8.3], p = 0.02). Full-time employment was predictive of higher VAS satisfaction (β = 14.1 [4.3, 23.9], p = 0.006) and higher Kujala score (β = 8.7 [0.9, 16.5], p = 0.03).

CONCLUSION

Markers of higher socioeconomic status including having a general check-up in the year prior to surgery, home ownership, and full-time employment were predictive of shorter time to initial evaluation, shorter time to surgery, and superior postoperative outcomes.

LEVEL OF EVIDENCE

 IV, retrospective case series.

Long-Term Follow-Up of the Roux-Goldthwait Patellar Stabilization Procedure in a Predominantly Adult Population

Background The Roux-Goldthwait patellar stabilisation (R-G) involves the medial transfer of the distal attachment of the lateral half of the patellar tendon. This paper reviews the long-term results of the R-G in a predominantly adult population. Methodology This is a retrospective study looking at patients with recurrent patellar instability who were treated with an R-G technique by a single surgeon over a 36-year period from 1976 to 2012. The primary outcomes measured were further patella instability and further knee surgical procedures. Results A total of 202 knees in 170 patients were analysed in this study. Patients between the ages of 9 and 70 years old (average 21 years old) were included in this study. The operative procedure changed during the study period. Initially, patients did not undergo concurrent arthroscopy. Early patients were likely to have additional lateral releases and open medial reefing procedures. More recent patients were more likely to undergo an isolated R-G procedure via a minimally invasive incision. The most common further operative procedure was arthroscopy of the knee for chondral pathology at 13.9%. These were more common early in the study period when patients did not have an initial arthroscopy. Recurrent dislocation was reported at 12.9%, with 5.9% of patients having revision stabilisation surgery, at a mean of 5.58 years (range = 1-15 years) postoperatively. Conclusions The R-G procedure is effective in treating recurrent patellar instability in both the paediatric and adult population. It can be performed as an isolated and minimally invasive procedure which is technically simple and has low morbidity.

Medial patellofemoral ligament reconstruction in skeletally immature patients without correction of bony risk factors leads to acceptable outcomes but higher failure rates

OBJECTIVES

To report outcomes and re-dislocation rates of medial patellar stabilizers reconstruction without bone procedures for correction of anatomical risk factors for patellar instability in skeletally immature patients; to compare isolated medial patellofemoral ligament (MPFL) reconstruction to combined MPFL and medial patellotibial ligament (MPTL) reconstruction in this population.

METHODS

Patients with open physis and bone abnormalities including patella alta and/or increased tibial tubercle-trochlear groove (TT-TG) distance and/or trochlear dysplasia underwent MPFL reconstruction, either isolated or associated with MPTL reconstruction. Preoperative, 1-year follow-up and the latest follow-up (5 years minimum) data were collected. Radiological and clinical evaluations were conducted, with special attention to failure rate. Comparison of results from isolated MPFL and combined MPFL/MPTL reconstructions was performed.

RESULTS

Twenty-nine patients were included, 19 in the isolated MPFL group (median 14 years old; follow-up 5.8 ​± ​1.7 years) and 10 in the combined MPFL/MPTL group (median 13.5 years old; follow-up 5.2 ​± ​1.4 years). Kujala and Tegner scores increased over time, although without statistically significant differences between the two groups at the latest follow-up (p ​= ​0.840 and p ​> ​0.999, respectively). During follow-up, 5 of 19 (26.3%) isolated MPFL and 2 of 10 (20%) MPFL/MPTL reconstructions experienced recurrence of patellar dislocation (p ​> ​0.999). Trochlear dysplasia type D (p ​= ​0.028), knee rotation (p ​= ​0.009) and lateral patellar tilt angle (p ​= ​0.003) were associated with patellar instability recurrence. The isolated MPFL group showed increased laxity on physical exam at the latest follow-up compared to the 1-year follow-up (patellar glide test (p ​= ​0.002), patellar tilt test (p ​= ​0.042) and subluxation in extension (p ​= ​0.019). This increased laxity was not observed in the MPFL/MPTL group (p ​> ​0.999). Comparing both groups, the glide test was significantly better in the combined MPFL/MPTL group in comparison to the isolated MPFL reconstruction group at the latest follow-up (p ​= ​0.021).

CONCLUSION

MPFL reconstruction in isolation or combined with MPTL reconstruction in skeletally immature patients with additional uncorrected anatomical patellofemoral abnormalities leads to acceptable clinical outcomes within a minimum of 5 years follow-up, although has a high failure rate of 24.1%. Addition of a MPTL reconstruction to the MPFL may result in decreased patellar laxity on physical exams, as demonstrated by better patellar glide test, patellar tilt test and subluxation in extension.

LEVEL OF EVIDENCE

Level III; retrospective cohort study.

Allografts for Medial Patellofemoral Ligament (MPFL) Reconstruction in Adolescent Patients with Recurrent Patellofemoral Instability: A Systematic Review

This systematic review updates the currently available evidence on medial patella-femoral ligament (MPFL) reconstruction using allografts. The outcomes were measured with patient-reported outcome measures (PROMs), redislocation and complication rates. This study was performed according to the 2020 PRISMA guidelines using the PubMed, Scopus, Web of Science databases, accessed in February 2023. Studies examining the clinical outcomes of MPFL reconstruction with allografts in adolescents and children with recurrent patellofemoral instability (PFI) were included. Data from three trials, including 113 surgical procedures in 121 children, were retrieved. 40% (48/121) of the included patients were girls. The mean age of the patients was 14.7 ± 0.8 years, and the mean follow-up length was 38.1 ± 16.5 months. With MPFL allograft reconstruction, the Kujala score improved by 14.7% (p < 0.0001) and the IKDC by 38.8% (p < 0.0001). The rate of dislocations was 5% (6 of 121), reoperation for instability was 11% (13 of 121), and subluxation was 2% (1 of 47). Conclusion: These results encourage the use of allografts for MPFL reconstruction in adolescent patients with recurrent patellofemoral instability. Though patellofemoral instability is common in clinical practice, the current literature lacks clinical evidence on allograft MPFL reconstruction. Additional high-quality investigations are required to properly establish the long-term advantages of allograft MPFL and its complication rate.

Radiographic Changes After Medial Patellofemoral Ligament Reconstruction in Skeletally Immature Patients Compared With an Age- and Sex-Matched Cohort

BACKGROUND

Despite recent evidence that medial patellofemoral ligament reconstruction (MPFLR) in the skeletally immature patient is both safe and effective, there are limited data evaluating postoperative coronal- and sagittal-plane growth and radiographic patellofemoral parameters in this population.

PURPOSE

The primary purpose was to assess radiographic measures of coronal-plane alignment, longitudinal growth, patellar congruence, and trochlear dysplasia after MPFLR in a skeletally immature population. A secondary purpose was to assess this population compared with a matched cohort with a focus on trochlear dysplasia prevalence and the effect of MPFLR on patellar height.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 28 children with a minimum 1-year follow-up who underwent isolated MPFLR were identified. All patients were skeletally immature, defined as fully open physes on both sides of the knee joint, at the time of surgery. The development of a limb length discrepancy or angular growth abnormalities were assessed on standing hip-to-ankle radiographs, patellar tilt and congruence were measured on the Merchant view of the knee, and the grade of trochlear dysplasia and patellar height were assessed on lateral knee radiographs. A sex- and age-matched group of patients who underwent anterior cruciate ligament reconstruction was formed as a control for patellar height and trochlear dysplasia measurements.

RESULTS

The mean patient age was 11.71 ± 2.02 years at the time of surgery with a mean follow-up of 23.54 ± 12.49 months. All but 1 patient in the MPFLR group had preoperative features consistent with trochlear dysplasia. There was no significant difference in limb length or coronal-plane alignment at final follow-up (P = .725 and P > .999, respectively). Both the MPFLR and the anterior cruciate ligament reconstruction groups had a statistically significant decrease in the Caton-Deschamps index between the preoperative and postoperative time points (mean, 0.18 ± 0.20 and 0.11 ± 0.14, respectively; P = .161).

CONCLUSION

MPFLR may be safely performed utilizing an epiphyseal femoral socket in a skeletally immature cohort without affecting normal longitudinal growth or coronal limb alignment. The previously reported effect of MPFLR in reducing patellar height may be related to physiological growth based on similar changes noted in a comparison cohort that did not undergo the procedure.

Outcomes, Return to Sport, and Failures of MPFL Reconstruction Using Autografts in Children and Adolescents with Recurrent Patellofemoral Instability: A Systematic Review

INTRODUCTION

This study systematically reviews and updates the current evidence on the outcomes of medial patellofemoral ligament (MPFL) reconstruction using autografts in children and adolescents with recurrent patellofemoral instability. The outcomes of interest were improvements in patient reported outcomes measures (PROMs), return to sport rates, and the rates of surgical failure.

METHODS

This systematic review was performed according to the 2020 PRISMA guidelines. The following electronic databases were accessed in October 2022: PubMed, Scopus, Web of Science. All the clinical studies which investigated the outcomes of MPFL reconstruction using autografts in children and adolescents with recurrent patellofemoral instability were accessed. Only studies which included patients younger than 18 years were considered. Techniques, case reports, guidelines, comments, editorials, letters, protocols, reviews, and meta-analyses were excluded. Studies which included patients with congenital or acute patellofemoral instability were not eligible, nor were those which focused exclusively on hyperlaxity.

RESULTS

Data from 477 patients (510 procedures) were retrieved. Of the patients, 41% (196 of 477) were women. The mean length of follow-up was 33.7 ± 28.8 months. The mean age of the patients was 14.6 ± 1.6 years. At the last follow-up, all PROMs of interest were statistically improved. The mean time to return to sport was 6.1 ± 1.1 months. Of the patients, 27% reduced their level of activity after surgical stabilization. A total of 87% of patients returned to practice sport. A total of 5% (26 of 477) and 2% (9 of 363) of patients experienced further dislocations and subluxations, respectively, during the follow-up period. Moreover, 4% (16 of 403) of patients underwent a further surgical procedure for patellofemoral instability within the follow-up period.

CONCLUSION

MPFL reconstruction using autografts is effective in children and adolescents with recurrent patellofemoral instability.

Posterior Approach With Small Incision Is a Safe Alternative to Anterior Approach for Hamstring Autograft Harvest in Adolescents

Background

There are potential drawbacks and complications associated with using the anterior approach to harvest the hamstring tendon as an autograft source for anterior cruciate ligament (ACL) and medial patellofemoral ligament (MPFL) reconstruction. A posterior harvest technique has been described as an alternative to an anterior approach in skeletally mature patients. The 2 approaches have not been compared in adolescents.

Purpose

We sought to compare the incision size and harvested tendon length produced by anterior and posterior hamstring harvest techniques in an adolescent population.

Methods

After obtaining consent, we prospectively collected data on a consecutive series of 115 adolescents undergoing ACL or MPFL reconstruction, including the length of the incision and of the harvested hamstring tendon. Demographic information including age, sex, and body mass index (BMI) was collected at the time of surgery.

Results

The mean age at the time of surgery was 14.3 ± 1.8 years (range: 9-21 years), and 43% (N = 50) of participants were male. Of the 115 hamstring autografts, 26 were harvested anteriorly and 89 were harvested posteriorly. Neither mean semitendinosus length nor mean gracilis length was significantly different when harvested anteriorly versus posteriorly. The posterior harvest group had a mean incision length that was significantly smaller than that of the anterior harvest group. No iatrogenic nerve injuries or neurovascular complications were observed in either group.

Conclusion

A posterior incision for hamstring autograft harvest provided an alternative approach in adolescents, which resulted in a 20% smaller incision than an anterior approach. For procedures such as MPFL reconstruction that do not require concomitant anteromedial work, posterior hamstring harvest may be used to improve cosmesis while producing viable hamstring autograft tissue for surgical reconstruction.

Medial Patellofemoral Ligament Reconstruction in the Pediatric Population: Skeletal Immaturity Does Not Affect Functional Outcomes but Demonstrates Increased Rate of Subsequent Knee Injury

Purpose

To evaluate short- to mid-term-outcomes, including instability rates, following medial patellofemoral ligament (MPFL) reconstruction in skeletally immature versus mature pediatric patients.

Methods

Patients younger than age 18 with recurrent patellar instability who underwent primary allograft MPFL reconstruction by a single surgeon from 2013 to 2019 were identified. Skeletally immature patients underwent all-epiphyseal drilling and mature patients underwent metaphyseal drilling at the Schöttle’s point. Patients 1 year from surgery were contacted to complete questionnaires, which included the International Knee Documentation Committee score. Further data included chart and imaging review. Significance was determined by P < .05.

Results

Of 118 eligible patients, 88 completed questionnaires. There were 67 skeletally mature and 21 skeletally immature patients. The mature group was older (15 vs 13 years, P < .001), predominantly female (67 vs 43%, P = .046), and heavier (24.7 vs 18.9, P < .001). Trochlear dysplasia (P = .594), concomitant procedures (P = .336), graft choice (P = .274), and follow-up length (P = .107) did not differ, although mature patients more often underwent suture tape augmentation (68 vs 13%, P < .001). Immature patients had greater rates of ipsilateral injury (35 vs 16%, P = .043); redislocation rate did not differ (9 vs 3%, P = .225). Mature patients were more likely to respond “definitely yes or probably yes” when asked if they would undergo the same care if needed (96 vs 76%, P = .007). At minimum 2-year follow-up, subsequent ipsilateral injury rates did not differ, although willingness to undergo the same care remained significant (95 vs 69%, P = .010). In a multivariable elimination logistic regression model, skeletal maturity was the only variable associated with subsequent ipsilateral injury (P = .049).

Conclusions

Pediatric patients undergoing MPFL reconstruction have good and comparable outcomes regardless of skeletal maturity. However, younger age and lack of tape augmentation in skeletally immature patients may predispose them to subsequent injury.

Level of Evidence

III, case-control study.

Management of Patellar Instability: A Network Meta-analysis of Randomized Control Trials

BACKGROUND

Multiple surgical options exist for the treatment of patellar instability; however, the most common procedures involve either a reconstruction of the medial patellofemoral ligament (MPFL) or a repair/plication of the MPFL and medial soft tissues.

PURPOSE

To perform a network meta-analysis of the randomized controlled trials (RCTs) in the literature to compare MPFL reconstruction, MPFL repair, and nonoperative management for patellar instability.

STUDY DESIGN

Systematic review and network meta-analysis; Level of evidence, 1.

METHODS

The literature search was performed based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. RCTs comparing MPFL reconstruction, MPFL repair, and nonoperative management for patellar instability were included. Clinical outcomes included recurrent instability (including both dislocations and subluxations), redislocation, and Kujala score. Clinical outcomes were compared using a frequentist approach to network meta-analysis, with statistical analysis performed using the statistical software R. The treatment options were ranked using P scores.

RESULTS

There were 13 RCTs with a total of 789 patients, all with a minimum follow-up of 24 months. There were 150 patients treated using MPFL reconstruction, 353 treated using MPFL repair, and 286 treated nonoperatively. Overall, MPFL reconstruction had the highest P score (0.9967) and resulted in a significantly lower recurrence rate than did MPFL repair (odds ratio [OR], 0.42; 95% CI, 0.07-0.72) and nonoperative management (OR, 0.09; 95% CI, 0.03-0.32). In addition, MPFL repair resulted in a significantly lower recurrence rate than did nonoperative management (OR, 0.42; 95% CI, 0.25-0.70). MPFL reconstruction had the highest P score (0.9651) and resulted in a significantly higher Kujala score than did nonoperative management (mean difference, 10.45; 95% CI, 0.41-20.49) but not MPFL repair (mean difference, 0.15; 95% CI, 0.03-0.68). Subgroup analysis revealed that MPFL reconstruction had the highest P score for all outcomes in those with first-time dislocation.

CONCLUSION

The current study demonstrated that MPFL reconstruction results in the lowest rate of recurrent patellar instability and best functional outcomes as measured using the Kujala score.

Revision surgery for failed medial patellofemoral ligament reconstruction results in better disease-specific outcome scores when performed for recurrent instability than for patellofemoral pain or limited range of motion

PURPOSE

Medial patellofemoral ligament reconstruction (MPFL-R) is an important treatment for recurrent patellar instability. Although complications such as redislocation, patellofemoral pain (PFP) and restricted knee range of motion have been reported, few studies have investigated the results of revision surgery for failed MPFL-R. Thus, the aim of this study was to determine the results of the tailored revision surgery after considering the cause of the reconstruction failure.

MATERIALS AND METHODS

Between 2015 and 2019, 28 patients (male/female 9/19; age 26.2 ± 6.4 years) underwent revision surgery for failed MPFL-R. The patients were grouped into the "recurrent instability" (SG1) group and "PFP" and/or "restricted range of motion" (SG2) group. Preoperatively, the clinical data, anatomical risk factor profile, and position of the femoral MPFL tunnel were determined for each patient. The Banff Patella Instability Instrument 2.0 (BPII 2.0) and numerical analogue scale (NAS 0-10) were administered preoperatively and at the final follow-up for the subjective assessment of the PFP and knee joint function.

RESULTS

Overall, the BPII 2.0 score improved from 28.8 ± 16.6 points preoperatively to 68.0 ± 22.7 points (p < 0.0001) postoperatively. SG1 exhibited an increase in the BPII 2.0 score from 28.9 ± 20.2 points to 75.7 ± 23 points (p < 0.0001). PFP decreased from 6.8 ± 2.4 to 1.6 ± 1.9 (p < 0.0001), while the knee joint function increased from 4.3 ± 2.5 to 8.8 ± 1.6 (p < 0.0001). In SG2, the BPII 2.0 score increased from 28.7 ± 12.6 points preoperatively to 57.7 ± 19.7 points (p = 0.0002) postoperatively and was thus significantly lower than that in SG1 (p = 0.038). The intensity of PFP decreased from 6.6 ± 3.0 preoperatively to 2.1 ± 1.9 postoperatively (p = 0.0006), while the subjective knee joint function improved from 3.2 ± 1.4 preoperatively to 7.6 ± 2.3 postoperatively (p < 0.0001). The differences between the groups were not significant.

CONCLUSION

Tailored revision surgery for failed MPFL-R significantly improves the patient-reported disease-specific quality of life. The study results indicate that patients undergoing revision surgery as a consequence of patellar redislocation appear to benefit more from revision surgery than those patients undergoing revision due to postoperative PFP and/or a limited knee joint range of motion.

LEVEL OF EVIDENCE

Level IV.

Medial Patellofemoral Ligament Reconstruction Using Adductor-Transfer and Adductor-Sling at Nonanatomic Femoral Attachment Sites Leads to Unfavorable Graft-Length Change Patterns: A Descriptive Biomechanical Study

PURPOSE

To compare the graft length change patterns in nonanatomic adductor-transfer (AT) and adductor-sling (AS) medial patellofemoral ligament (MPFL) reconstruction with those in anatomic MPFL reconstruction (MPFLR) and to investigate the favorable isometric ranges (FIRs) of knee flexion.

METHODS

Eight small fresh-frozen cadaveric knees were mounted in a knee-customized jig with tensioned muscles to measure graft length changes from two patellar points to four femoral attachments using a linear variable displacement transducer. Femoral attachments were at the MPFL footprint center (MPFL-C) in anatomic MPFLR, adductor magnus (AM) footprint center (AM-C) in AT, and at 5-mm (AM-5) or 10-mm (AM-10) points proximal to AM-C in AS. The FIRs of these femoral attachments were determined after zeroing the graft length changes at different initial fixation angles.

RESULTS

Anatomic MPFL-C resulted in almost isometric graft length changes from 0° to 90°. At AM-C, the graft length changes displayed an increase from 0° to 45° and significantly greater length changes than those at MPFL-C from 60° to 90°. The graft length changes at both AM-5 and at AM-10 continuously increased with knee flexion angles and presented significantly larger graft length changes than those at MPFL-C and at AM-C from 30° to 90° and 60° to 90°, respectively. After zeroing graft length changes at different fixation angles, the FIRs of the MPFL-C covered all knee flexion angles, regardless of the patellar attachments and initial fixation angles. Moreover, with the smaller FIRs of AM-C observed at any fixation angle when compared with MPFL-C, fixing the graft at 0° to 30° in AT allowed the FIRs to cover the whole functional flexion range. However, the significantly larger graft length changes of both AM-5 and AM-10 resulted in extremely limited FIRs at any fixation angle.

CONCLUSION

Anatomic MPFL-C resulted in a favorable graft length change range (less than 2 mm) at 0° to 90° of knee flexion, which was close to the isometric graft behavior. However, nonanatomic attachments of AM-C in AT, and both AM-5 and AM-10 in AS caused significant anisometric graft length change patterns and limited FIRs. Moreover, AT had a smaller range of graft length change but wider FIRs compared to AS, indicating superior graft behavior for MPFLR.

CLINICAL RELEVANCE

Anatomic MPFLR is preferable for the treatment of in skeletally immature patients, followed in preference by nonanatomic AT. Nonanatomic AS should be performed cautiously.

Comparable outcome for autografts and allografts in primary medial patellofemoral ligament reconstruction for patellofemoral instability: systematic review and meta-analysis

PURPOSE

This study updates the current evidence on the role of allografts versus autografts for medial patellofemoral ligament (MPFL) reconstruction in patients with patellofemoral instability.

METHODS

The study was performed according to the PRISMA guidelines. In March 2021, a literature search in the main online databases was performed. Studies reporting quantitative data concerning primary MPFL reconstruction using an allograft were considered for inclusion. The Coleman Methodology Score was used to assess the methodological quality of the selected articles.

RESULTS

Data from 12 studies (474 procedures) were retrieved. The mean follow-up was 42.2 (15-78.5) months. The mean age was 21.1 ± 6.2 years. 64.9% (285 of 439) of patients were female. At the last follow-up, the Tegner (p < 0.0001), Kujala (p = 0.002) and the Lysholm (p < 0.0001) scores were minimally greater in the autografts. The similarity was found in the rate of persistent instability sensation and revision. The allograft group evidenced a lower rate of re-dislocations (p = 0.003).

CONCLUSION

Allografts may represent a feasible alternative to traditional autograft for MPFL reconstruction in selected patients with patellofemoral instability. Allograft tendons yielded similar PROMs, rates of persistent instability, and revision. Allograft reconstructions tended to have modestly lower re-dislocation rates.

LEVEL OF EVIDENCE

IV.

Midterm Results After Isolated Medial Patellofemoral Ligament Reconstruction as First-Line Surgical Treatment in Skeletally Immature Patients Irrespective of Patellar Height and Trochlear Dysplasia

BACKGROUND

Medial patellofemoral ligament reconstruction in skeletally immature patients who experience lateral patellar dislocation has been reported to yield good results. Whether bony abnormalities such as patellar height and trochlear dysplasia should be addressed additionally is a topic of discussion.

PURPOSE

To evaluate patient-reported outcomes and redislocation rates after isolated medial patellofemoral ligament reconstruction as first-line surgical treatment for lateral patellar dislocation in skeletally immature patients. Further, to analyze epidemiological, intraoperative, and radiographical factors influencing redislocation and clinical outcome.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Prospectively collected data were retrospectively analyzed for adolescent patients younger than 16 years who underwent medial patellofemoral ligament reconstruction between 2014 and 2018. Inclusion criteria were isolated medial patellofemoral ligament reconstruction with gracilis tendon and availability of accurate pre- and postoperative radiographs with the presence of open physes. The patients were questioned regarding further surgery, redislocation, and clinical outcomes using the Tegner Activity Scale, International Knee Documentation Committee (IKDC) Subjective Knee Form, Lysholm score, and Kujala score. The influence of diverse epidemiological, intraoperative, and radiographical parameters on the redislocation rates and clinical outcome was analyzed.

RESULTS

A total of 54 medial patellofemoral ligament reconstructions (49 patients) met the inclusion criteria. After 4.3 ± 1.7 years (range, 2.0-7.3 years), 45 reconstructions (83.3%) in 41 patients were available for follow-up. The distribution of trochlear dysplasia was as follows: type A and B, 19 cases (42.2%) each; type C, 6 cases (13.3%); and type D, 1 case (2.2%). Patellar redislocation occurred in 3 patients (6.7%). The mean Tegner, subjective IKDC, Lysholm, and Kujala scores at follow-up were 6.3 ± 1.6 (range, 3-9), 93.6 ± 8.8, 95.9 ± 7.4, and 97.9 ± 7.1, respectively. Patellar height and trochlear dysplasia had no influence on redislocation or clinical scores. The Lysholm score was lower in knees with intraoperative retropatellar chondral lesion grade ≥III versus grade <III (89.0 ± 19.2 vs 96.9 ± 3.6, respectively; P = .023); likewise, the Kujala score was lower in knees that were grade ≥III versus grade <III (90.0 ± 19.7 vs 98.1 ± 2.1, respectively; P = .015).

CONCLUSION

Isolated medial patellofemoral ligament reconstruction as first-line surgical treatment in skeletally immature patients yields excellent midterm results, irrespective of patellar height and trochlear dysplasia. Redislocation still occurs in a certain number of patients, and a higher degree of retropatellar chondral lesion is a predictor for a worse clinical outcome.

The Superficial "Swing-Down" Quadriceps Tendon Autograft Is a Viable Option for Medial Patellofemoral Ligament Reconstruction: A Systematic Review

PURPOSE

The purpose of this systematic review is to ascertain the reported clinical outcomes and complication profiles of medial patellofemoral ligament (MPFL) reconstruction performed using a superficial "swing-down" quadriceps tendon autograft.

METHODS

Three databases (PubMed, EMBASE, and MEDLINE) were searched from January 1, 2000, to April 06, 2020. Keywords used in the search included: "medial patellofemoral ligament" and "reconstruction". After screening based on inclusion and exclusion criteria, patient demographics, graft type, outcomes, and complications were extracted. Methodological Index for Non-Randomized Studies criteria were used to assess the quality of each included study.

RESULTS

Eleven studies were included, comprising data from 226 patients with mean follow up ranging from 12 to 38 months. All reconstructions used a superficial "swing-down" quadriceps tendon autograft fixed at 20-30 degrees of knee flexion where reported. Eight of eleven studies reported significant improvement in patient reported outcomes such as Kujala score, Lysholm score, and Tegner score. The mean preoperative Kujala score ranged from 35.8 to 82.1 (167 patients), while the mean postoperative Kujala score ranged from 88.4 to 94.8 (197 patients). The mean of the preoperative Lysholm score ranged from 43.3 to 79.3 (77 patients), while the mean of the postoperative Lysholm score ranged from 81.9 to 90.9 (99 patients). The I² statistic for Lysholm and Kujala scores was 94% and 97%, respectively. Across data reported on 194 patients, there was no incidence of patellar redislocation, patellar fracture, or graft site morbidity.

CONCLUSION

The quadriceps tendon produced improved clinical outcomes with low rates of recurrent postoperative patellar dislocation. These data suggest that the quadriceps tendon remains a suitable alternative for MPFL reconstruction and should remain part of the arsenal of knee ligament surgeons.

LEVEL OF EVIDENCE

Systematic review of Level III and IV studies.

Complications and Recurrence of Patellar Instability after Medial Patellofemoral Ligament Reconstruction in Children and Adolescents: A Systematic Review

Background: This study aimed to review the data available in the current literature concerning the complications and recurrence of instability following medial patellofemoral ligament (MPFL) reconstruction for patellar instability in young and adolescent patients (those <20 years old). Methods: A systematic review was performed based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. Two independent reviewers searched the PubMed, Scopus, EMBASE, and Cochrane databases. The terms “medial patellofemoral ligament” or “MPFL” and “reconstruction” and “young” or “adolescents” or “children” were used. The inclusion criteria for the literature review comprised studies that reported the complications and recurrences of instability in patients who had undergone MPFL reconstruction for patellar instability. Results: In all, 332 patients were included in the review, of which 195 were females (63.5%) and 112 were males (36.5%), and they totaled 352 treated knees. The mean age at the time of the surgery was 14.28 years, and the mean follow-up duration was 30.17 months. A total of 16 (4.5%) complications were reported: one (0.3%) patella fracture, one (0.3%) screw removal due to intolerance, one (0.3%) infection, five (1.4%) wound complications, six (1.7%) subluxations and two (0.6%) instances of post-operative stiffness. A total of 18 (5.1%) recurrences of patellar instability were recorded. Conclusions: MPFL reconstruction in young patients can be considered an effective and safe treatment leading to clinical improvement in terms of recurrence of dislocation. No major complications related to the technique were reported, but a high level of research evidence is required to better evaluate the clinical results in a long-term follow-up.

Medial Patellofemoral Ligament Reconstruction Using a Quadriceps Tendon Autograft in a Patient with Open Physes

Recurrent patellar dislocations are correlated with an elevated risk for further patellar dislocations. Chronic patellar instability is a disabling issue for some patients and may require surgical intervention for proper treatment. Risk factors for recurrent dislocations include medial patellofemoral ligament (MPFL) tears, patella alta, trochlear dysplasia, and increased tibial tubercle to trochlear groove distance. Surgical management must be based on a patient's unique joint pathoanatomy and typically requires medial patellofemoral ligament reconstruction, with or without accompanying procedures such as tibial tubercle osteotomy or sulcus-deepening trochleoplasty. Chronic patellar instability in minors with open growth plates, requires alternative MPFL reconstruction techniques to prevent physeal injury, because of the close proximity of the femoral physis to the MPFL insertion. This article discusses the authors' preferred technique for surgical treatment of recurrent patellar instability with a medial patellofemoral ligament reconstruction using a quadriceps tendon autograft.

Medial Patellofemoral Complex Advancement for Recurrent Lateral Patellar Instability and Selective Acute Primary Patellar Dislocations

Medial patellofemoral complex (MPFC) is considered as the primary medial patellar restraint and has a static, as well as dynamic, component. MPFL reconstruction (MPFL-R) restores only the static component of MPFC, is associated with multiple technical concerns, and has a steep learning curve. Need for physeal sparing techniques and relatively high rates of complications including patella fracture are some other concerns with MPFL-R. We propose a simple procedure for advancement of MPFC onto patella, which is indicated in most of the recurrent lateral instabilities (with a positive lateral glide test result and an intact MPFL on magnetic resonance imaging). The procedure is also indicated in selective acute primary dislocations-those with associated chondral lesions and magnetic resonance imaging-documented isolated patellar side avulsion/injury. MPFC advancement is a more anatomical procedure that also restores dynamic medial checkrein of patella and can be performed even by a novice surgeon. MPFC advancement is devoid of the multiple technicalities of MPFL-R, does not require intraoperative imaging or any postoperative immobilization, and renders complications like donor graft-site morbidity and patella fractures irrelevant. It requires no modifications in patients with open physes and can be performed in isolation or with other procedures as per à la carte principle.

Update on Patellar Instability

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

Medial Patellofemoral Ligament Reconstruction and Lateral Retinacular Lengthening in the Skeletally Immature Patient

Patellar instability remains a ubiquitous and troublesome problem in orthopaedics and represents a challenge in the pediatric population. Reconstruction of the medial patellofemoral ligament (MPFL) has become a mainstay of patellar instability management in recent years. As with any procedure at or around the physes, there is concern among surgeons regarding safe placement of hardware and drilled tunnels. The authors describe a technique for anatomic MPFL reconstruction with the aid of fluoroscopic guidance to maintain a "safe zone" without violating the distal femoral physis. This technique allows for reliable MPFL reconstruction in the skeletally immature population with concomitant lateral lengthening, while requiring only minor deviations from the procedure in a skeletally mature patient.

Editorial Commentary: Medial Patellofemoral Ligament Reconstruction: Are We Overtensioning the Graft?

While medial patellofemoral ligament reconstructions result in a high rate of return to sports, there is still a high reported complication rate. One area of controversy regarding the technique for the reconstruction is the knee flexion angle to use during graft fixation. Currently, more evidence is needed to determine whether there is a significant benefit to using a particular flexion angle during graft fixation.