Recurrent Patellar Instability Research Articles

Trends in Lateral Retinacular Release from 2010 to 2017.

Historically, lateral retinacular release (LRR) procedures have been utilized in the treatment of a variety of patellofemoral disorders, including lateral patellar instability. However, in the past decade, there has been an increasing awareness of the importance of the lateral stabilizers in patellar stability, as well as the complications of LRR, such as recurrent medial patellar instability. The purpose of this study was to investigate current trends in LRR procedures from 2010 through 2017 using a large national database. The American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database was queried for arthroscopic LRR procedures (the Current Procedural Terminology [CPT] code, 29873) from 2010 to 2017. The number and incidence of lateral release procedures, both isolated and nonisolated, were analyzed and separated into cohorts for analysis. Age and gender of the LRR cohort was investigated and compared with all other orthopaedic procedures during the same time period in the NSQIP database. In addition, concomitant procedures and associated International Classification of Disease-9th Revision (ICD-9) and ICD-10th Revision (ICD-10) codes were analyzed over time and between LRR groups. From 2010 to 2017, 3,117 arthroscopic LRRs were performed. The incidence for LRR was 481.9 per 100,000 orthopaedic surgeries in 2010 and significantly decreased to 186.9 per 100,000 orthopaedic surgeries in 2017 (p < 0.01). LRR was more commonly performed in females (66%) and 58% of patients were under 44 years of age. In addition, LRR was most commonly performed with a concomitant meniscectomy (36%), synovectomy (19%), or microfracture (13%), and for a diagnosis of pain (22%). The overall incidence of LRR procedures significantly decreased from 2010 to 2017. LRRs were more commonly performed in younger, female patients for a diagnosis of pain with the most common concomitant procedure being meniscectomy, synovectomy, or microfracture.

Outcomes of MPFL reconstruction with tibial tubercle transfer for recurrent patellar instability with high grade trochlear dysplasia in Indian population

BackgroundPatellar instability is a painful condition which affects the quality of life and mobility of young individuals. The aim of this study is to observe the results of medial patello-femoral ligament reconstruction with hamstring autograft along with a modified Fulkerson osteotomy, for recurrent instability of patella with high-grade trochlear dysplasia in Indian population. Materials & methodsWe conducted a prospective observational study of 26 knees (21 patients) who attended our outpatient department from June 2014 to February 2019, with recurrent instability of the patella and high-grade trochlear dysplasia. All knees were treated with MPFL reconstruction with hamstring autograft and modified Fulkerson osteotomy. ResultsThe mean follow-up period was 30 months (range: 24–50). The mean Lysholm scores improved from 49.9 (range: 30–63) preoperatively to 82.5 (range: 51–100) (p < 0.05), Kujala scores from 55.5 (36–67) to 85.9 (55–100) and International Knee Documentation Committee (IKDC) scores from 50.2 (31.6–62.3) to 82.9 (54.7–98.3) (p < 0.05) at 2 years follow-up. TT-TG distance decreased from 21.2 mm (18–25) to 11.6 mm (10–13) (p < 0.05) and patellar tilt angle decreased from 24.2° (18°-35°) to 7.2° (5°-10°) (p < 0.05). One knee had superficial skin infection in immediate post-operative period. Three knees had postoperative stiffness, which improved on manipulation under anesthesia. Six knees had implant irritation from the osteotomy screws which were removed after bony union was achieved. Functional scores were low in two knees due to patello-femoral pain, but they did not have recurrent instability. ConclusionMPFL reconstruction with tibial tubercle transfer gives good functional outcomes in 92.3% patients with recurrent patellar instability, associated with high-grade trochlear dysplasia in Indian population.

MPFL Reconstruction in the Pediatric Population: Does Skeletal Maturity Matter?

Objectives:Patellar instability requiring medial patellofemoral ligament reconstruction (MPFL) in the pediatric population poses a challenge in that the isometric point of femoral fixation (Schottle’s point) is in close proximity to the distal physis. As a result, various alternative fixation techniques have been described to avoid physeal damage, however the consequences of this are unclear. Continued growth and altered graft mechanics in the growing child are areas of concern. The objective of the current study was to evaluate short to midterm outcomes, including redislocation rates, following MPFL reconstruction in skeletally immature versus mature pediatric patients.Methods:Patients under age 18 with recurrent patellar instability that underwent primary MPFL reconstruction by a single surgeon from 2013 to 2019 were identified using current procedural terminology (CPT) codes. Patients who were a minimum of 1 year from surgery were contacted to complete questionnaires. Questions pertained to knee pain and function, including International Knee Documentation Committee (IKDC) score, as well as further injury or surgery. Further data included chart and imaging review. Based on radiographic appearance of the distal physis, patients were placed into either the skeletally mature or immature cohort for comparison. Statistical analysis included chi-square, fisher’s exact, and Mann-Whitney U tests. Significance was determined by p-value <0.05.Results:There were 103 primary MPFL reconstructions in 94 patients: 70 skeletally mature and 24 immature. As expected, the skeletally mature group was older (15.5 vs. 13.1 years). Skeletally immature patients had a higher incidence of trochlear dysplasia (88 vs. 63%, p=0.04). No other baseline differences were identified. Average follow-up was similar at 4.1 years for the mature group and 3.5 years in the immature. Skeletally immature patients were more likely to sustain a subsequent dislocation or any ipsilateral knee injury (15 vs. 3%, p=0.03; 35 vs. 16%, p=0.04 respectively). Skeletally immature patients underwent more revision instability procedures, which trended towards but did not reach significance (23 vs. 9%, p=0.06). No significant difference was observed in IKDC score (80 each), perceived percent of normal for that knee (85% each), frequency of instability events, current sport participation (42 vs. 31%), sport avoidance (46 vs. 35%), or subjective stiffness (38 vs. 41%). Visual analog scale pain scores for skeletally immature compared to mature patients were not different at rest, with activities of daily living, or with sport (0.9 vs. 0.8, 1.5 vs. 1.7, 2.5 vs. 3 respectively). Significantly fewer patients in the skeletally immature group were satisfied (79 vs. 97%, p<0.05) and would undergo the surgery again (68 vs. 100%, p<0.05).Conclusions:In pediatric patients undergoing MPFL reconstruction, both skeletally immature and mature patients have good and comparable outcomes. However, those that are skeletally immature are more likely to have a subsequent ipsilateral injury or dislocation. These patients are also less likely to be satisfied with their results. Of note, there was a higher incidence of trochlear dysplasia in skeletally immature patients which may predispose them to subsequent injury.

SURGICAL MANAGEMENT OF PATELLAR INSTABILITY IN ADOLESCENTS WITH BODY MASS INDEX GREATER THAN 30

Background:Recurrent patellar instability is a common condition often requiring surgical stabilization in adolescents. Obesity, defined as body mass index (BMI) greater than 30 kg/m2 in adults, has been associated with poorer outcomes with many procedures including ACL reconstruction, spinal fusion, and joint arthroplasty. Data is limited regarding the results of surgery for patellar instability in adolescent patients with BMI > 30 kg/m2.Purpose:The purpose of this study was to report on rates of recurrent patellar instability following surgical management in adolescents with BMI >30 kg/m2 and to compare the rates of recurrent instability between different surgical procedures.MethodsA retrospective review of patients who underwent surgical management of patellar instability at our institution was performed. Inclusion criteria included patients aged 19 and younger, with BMI >30 kg/m2 who were followed for least 12 months post procedure. Patients with underlying collagen or systemic disorders, a history of prior ipsilateral knee surgery, or an osteochondral fragment greater than 10mm were excluded. Complications were defined as any recurrent subluxation or dislocation, or need for subsequent instability surgery. A subgroup analysis was performed to compare recurrent instability rates within our cohort between patients who underwent medial retinacular plication versus all other procedures. Categorical variables were compared using Fisher’s exact test. Statistical significance of p<0.05 was applied.Results:Fifty-five patients were identified. Mean age was 15.6±2.4 years. Mean BMI for this cohort was 34.9± 4.3 kg/m2. 72.7% of patients were female. All patients underwent either medial retincular plication, tibial tubercle osteotomy, MPFL reconstruction or combined procedures (Table 1). At a mean of 3.8 years, 16.4% of all patients had any recurrent subluxation or dislocation including 12.7% who had a recurrent dislocation, and 7.3% who required a revision patellar stabilization procedure. Subgroup analysis revealed that obese patients who underwent isolated medial retinacular plication had higher rates of recurrent subluxation or dislocation (24% vs 10%, p=0.272) including recurrent dislocation (20% vs 6.7%, 0.226), and had significantly higher rates of subsequent instability surgery (16% vs 0%, p=0.037) (Table 2).Conclusion:Adolescents with BMI > 30 who undergo patellar stabilization surgery have notable rates of recurrent subluxation or dislocation and subsequent instability surgery though comparable to results in non-obese patients. Obese patients who underwent medial retinacular plication had higher rates of postoperative instability and significantly higher rates of revision instability surgery compared to those who underwent MPFL reconstruction, tibial tubercle osteotomy or combined procedures.Tables/Figures:

CLINICAL OUTCOMES AFTER MEDIAL PATELLOFEMORAL LIGAMENT RECONSTRUCTION UTILIZING ALLOGRAFT TISSUE IN PEDIATRIC AND ADOLESCENT PATIENTS: MINIMUM 2-YEAR FOLLOW-UP

Background:Medial patellofemoral ligament (MPFL) reconstruction has gained popularity as a tool to manage recurrent patellar instability. The use of allograft for reconstruction includes benefits of quicker surgical time and obviating donor-site morbidity. In anterior cruciate ligament (ACL) reconstruction hesitancy exists to use allograft in younger patients based on data demonstrating higher graft failure rates. However, a similar trend of allograft failure has not been demonstrated for reconstruction of the MPFL, which has a lower tensile strength than that of the ACL.Hypothesis/Purpose:The purpose of this study is to evaluate outcomes including recurrent instability after MPFL reconstruction utilizing allograft tissue in pediatric and adolescent patients.Methods:A retrospective review was performed to identify patients of a single surgeon with MPFL reconstructions with allograft for recurrent patellar instability with minimum two-year follow-up. Surgical management was recommended after minimum six weeks of nonoperative management including bracing, physical therapy, and activity modification. Pre-operative x-rays were evaluated to assess physeal closure, lower extremity alignment and trochlear morphology, and Insall-Salvati and Caton-Deschamps ratios. MRIs were reviewed to evaluate the MPFL, trochlear morphology, and tibial tubercle trochlear groove distance (TT-TG). The allograft was fixed with a bioabsorbable screw. Descriptive statistics were used to characterize data. The primary outcome was recurrent instability.Results:20 patients (23 knees) 14 females (17 knees) with average age 15.8 years (range: 11.5-19.6 years) underwent MPFL reconstruction with allograft with average follow-up of 3.6 years (range: 2.2-5.9 years). Physes were open in 8 knees. Average Insall-Salvati ratio was 1.08 ± 0.16 and Caton-Deschamps index was 1.18 ± 0.15. Eighteen patients were noted to have trochlear dysplasia pre-operatively and TT-TG was 15.4 ± 3.9 mm. The three knees (13.0%) with complications had open physes – two (8.7%) had recurrent instability requiring subsequent operation and one sustained a patella fracture requiring open reduction internal fixation. The average Insall-Salvati of these three patients was 1.26 ± 0.21, Caton-Deschamps was 1.18 ± 0.21, and TT-TG was 18.3 ± 3.5mm. There were no growth disturbances noted post-operatively.Conclusion:MPFL reconstruction using allograft tissue may be performed safely in the pediatric and adolescent population with good outcomes at mid-term follow-up with few complications and low rate of recurrent instability. Anatomic factors for may contribute to recurrent instability and complications post-operatively, though larger numbers are needed for statistical analyses. Further prospective and randomized evaluation comparing autograft to allograft reconstruction is warranted to understand graft failure rates.

Medial patellofemoral ligament reconstruction for patellofemoral instability: a new surgical technique

&lt;p class="abstract"&gt;&lt;span lang="EN-US"&gt;The purpose of this study was to present new surgical technique for MPFL reconstruction. We also describe its functional outcome, complications, and the advantages of the procedure. This study is a prospective analysis of collected data during the period of august 2018 to January 2020. Ten cases of patients with recurrent symptomatic patellar instability and who underwent isolated MPFL reconstruction were included in the study. Kujala scoring and lysholm scoring was done to assess the functional outcome at follow-up. Post-operative dislocation and apprehension were recorded in each case along with any complication. Pre-operative Kujala score was 36.80 which improved to 89.80 postoperatively at the time follow-up. Pre-operative lysholm score was 36.80 which improved to 92.70 postoperatively at the time follow-up. The improvement in Kujala score and Lysholm score was found to be highly significant (p&amp;lt;0.01). We have done a simple technique where MPFL is reconstructed anatomically to restore kinematics and stability. Consistent good results with early rehabilitation can be obtained using the described technique.&lt;/span&gt;&lt;/p&gt;

Portuguese Translation and Cross-Cultural Adaption of the Banff Patella Instability Instrument.

Objective To translate into Brazilian Portuguese and to cross-culturally adapt the Banff Questionnaire for Patellar Instability. Methods The translation and cross-cultural adaptation followed the linguistic validation process proposed by international guidelines, which consists of six steps: translation, synthesis, back-translation, review by an expert committee, pretest, and final report presentation to the authors of the original questionnaire. Literate patients with recurrent patellar instability, older than 12 years of age, who signed the informed consent form or had it signed by a legal guardian were included in the study. Patients with neurological or systemic comorbidities were excluded from the study. Results A total of 62 patients (18 males and 44 females) were included in the study. Discrepancies observed during the processes of translation and harmonization of the back-translations were modified with no need for reformulation. No pretest version replacements were required. Conclusion The Banff Questionnaire for Patellar Instability has been successfully translated and cross-culturally adapted into Brazilian Portuguese, so it can be used to assess patients with patellar instability who speak this language.

Influence of tibial tuberosity position and trochlear depth on patellar tracking in patellar instability: Variations with Patella Alta

BackgroundPatella alta reduces articular constraints acting on the patella from the trochlear groove with the knee extended. The current study was performed to address how patella alta alters the influence of tibial tuberosity position and trochlear depth on patellar tracking in patients being treated for patellar instability. MethodsFifteen subjects with recurrent patellar instability participated in knee extension within a dynamic CT scanner. Computational models were reconstructed from the motions to characterize patellar lateral shift, patellar tilt, patellar height, trochlear depth and lateral position of the tibial tuberosity at 0° and 30° of knee flexion. Linear regressions were used to correlate patellar tracking with anatomy for an alta group (7 knees, Caton-Deschamps index > 1.2) and a non-alta group. FindingsFor the alta group, lateral patellar shift and tilt increased with increasing lateral position of the tibial tuberosity at 0° (r2 > 0.8, P < 0.005). For the non-alta group, lateral patellar shift and tilt increased as depth of the groove decreased at 0° (r2 > 0.8, P = 0.001). Lateral patellar tilt also increased with increasing lateral position of the tibial tuberosity at 30° for the non-alta group (r2 = 0.55, P = 0.04). InterpretationFor patients with patellar instability, lateral patellar maltracking with the knee extended can be largely attributed to either a shallow trochlear groove or a combination of patella alta and a lateral position of the tibial tuberosity. These relationships should be considered in both conservative and surgical treatment planning.

Failures and Complications with MPFL reconstruction: Our experience in 215 patients

Introduction:Chronic lateral patellar instability is one of the commonly seen clinical conditions encountered by knee surgeons. Medial patellofemoral ligament (MPFL) reconstruction has become mainstay treatment over the last three decades. Upto 26% complication rates have been reported in literature with MPFL reconstruction. The purpose of this study is to analyse failure rates, complications of surgery for PF instability and to identify the predictive factors for failure.Methods:A retrospective analysis of prospectively collected data was performed of all 215 (234 knees) patients who had undergone MPFL reconstruction between October 2007 and August 2018. All the cases with any postoperative complications or failures were included. A failure was defined by a postoperative patellar dislocation or surgical revision for recurrent patellar instability or anterior knee pain not resolving with conservative methods. Other complications such as stiffness, infection, neurological deficit and deep vein thrombosis were also included. Lysholm, Kujala, Tegner and radiographic features, such as trochlear dysplasia according to Dejour classification, patellar height with the Caton-Deschamps index (CDI), tibial tubercle-trochlear groove distance were analysed pre and post operatively.Results:Ten patients (4.27%) had a revision of MPFL reconstruction, seven patients (3%) had removal of their metal work. Post-operative stiffness was in only three patients (1.28%) and required manipulation under anesthesia. Six patients (2.56%) had patellofemoral replacement over time while three patients had arthroscopic debridement for cartilage related pathology. There was also one case each of femoral nerve palsy(related to the nerve block), post-operative deep infection, deep vein thrombosis?.Conclusion:To our knowledge, this is the only study recording the failures and complications of MPFL reconstruction on a large patient database. Age above 30, obesity, cartilage lesions, hyperlaxity and female gender are predictors of a poor subjective outcome. Identifying the potential risk factors preoperatively can prevent future complications.

Radiographic and Clinical Outcomes After Tibial Tubercle Osteotomy for the Treatment of Patella Alta: A Systematic Review and Meta-analysis

Background: Patella alta is a known risk factor for patellar instability and, in the setting of recurrent patellar instability with significant patella alta, correction of patellar height with a tibial tubercle osteotomy (TTO) may help decrease the failure of soft tissue–based stabilization. Purpose: To perform a systematic review and meta-analysis of radiographic and clinical outcomes after TTO for patella alta. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: PubMed, OVID/Medline, and Cochrane databases were queried in June 2020 for studies reporting outcomes of TTO for patella alta. Data pertaining to study characteristics and design, radiographic and clinical outcome values, and incidence of complications and reoperations were extracted. DerSimonian-Laird continuous and binary random-effects models were constructed to (1) perform subgroup-based analysis of mean changes in radiographic indices after TTO and (2) quantify the pooled incidence of complications and reoperations. Results: Eight studies including 340 patients (420 knees) with a mean age of 24.7 ± 8.4 years were included. The mean follow-up was 53.1 months (range, 3-120 months), with 1 study reporting a mean follow-up of less than 2 years. The pooled mean anterior transfer was 5.6 mm; the mean medial transfer was 8.7 ± 1.3 mm; and the pooled mean distalization of the tibial tubercle was 12.2 ± 4.5 mm. Continuous random-effects meta-analysis determined that significant reductions in the mean Insall-Salvati ratio (1.40 vs 0.98, P < .001), Caton-Deschamps index (1.26 vs 0.97, P < .001), and tibial tubercle to trochlear groove ratio (18.27 vs 10.69, P < .001) were observed after TTO. The overall incidence of complications was 7.6% (95% CI, 4.8%-10.5%), while the overall incidence of reoperations was 14.3% (95% CI 6.2%-22.4%). Conclusion: TTO for patellar instability in the setting of patella alta results in a significant decrease in patellar height with varying degrees of medialization depending on the utilized technique. A mean postoperative complication rate of 7.6% was reported with a reoperation incidence of 14.3%, related primarily to hardware removal.

Age at surgery is correlated with pain scores following trochlear osteotomy in lateral patellar instability: a cross-sectional study of 113 cases

BackgroundA trochlear osteotomy aims to restore patellar stability in patients with recurrent patellar instability and trochlear dysplasia. The age of patients at time of surgery could be a relevant factor which influences outcome. We hypothesized that lower age at time of surgery is associated with better patient-reported outcomes.MethodsA retrospective study was conducted on patients with patellar instability and trochlear dysplasia. Patients were contacted by phone for informed consent and were then asked to complete online patient-reported outcome measurements (PROMs). The PROMs consisted of the Kujala Knee Score (KKS) (Kujala et al., Arthroscopy 9(2):159-63, 1993; Kievit et al. Knee Surg Sports Traumatol Arthrosc. 21(11):2647-53, 2013), the Short Form 36-item health survey (SF-36v1) (Ware, Med Care 73-83, 1992; Aaronson et al., J Clin Epidemiol. 51(11):1055-68, 1998), and visual analog scale (VAS) scoring pain, instability, disability, and satisfaction on a 0–100 scale. Multivariable linear regression models were used to study the effect of age on the PROM scores.ResultsFor this study, 125 surgical procedures in 113 patients were included. Mean VAS pain at rest was 19 and at activity 38; mean Kujala score was 73. Multivariable regression analysis revealed that age at the time of surgery was correlated with VAS pain at rest, with a 0.95 increase of VAS score (scale 0–100) for every year of age. Recurrence of instability was observed in 13 (10%) knees.ConclusionIn this cross-sectional study, pain scores of 113 patients who have undergone a lateral facet elevating trochlear osteotomy for patellar instability were reported. Age at time of surgery was correlated with an increased pain score at rest with an average of 9.5 points (scale 0–100) for every 10 years of age. Age at time of surgery was not correlated with overall satisfaction.

Allograft Medial Patellofemoral Ligament Reconstruction in Adolescent Patients Results in a Low Recurrence Rate of Patellar Dislocation or Subluxation at Midterm Follow-Up

To evaluate rates of recurrent instability in adolescent patients with medial patellofemoral ligament (MPFL) reconstruction with allograft and associations of anatomic risk factors with complications. A retrospective review identified patients of a single surgeon who underwent MPFL reconstruction with allograft for recurrent patellar instability with minimum 2-year follow-up. Surgical management was recommended after a minimum 6 weeks of nonoperative management and included MPFL reconstruction with gracilis allograft using a double-bundle technique. Preoperative radiographs were evaluated to assess physeal closure, lower-extremity alignment, trochlear morphology, and Insall-Salvati and Caton-Deschamps ratios. Magnetic resonance images were reviewed to evaluate the MPFL, trochlear morphology, and tibial tubercle trochlear groove distance (TT-TG). Descriptive statistics were used to characterize data. The primary outcome was recurrent instability. 20 patients (24 knees; 18 knees in 14 females and 6 knees in 6 males; average age 15.7 years; range 11.5 to 19.6) underwent MPFL reconstruction with allograft (mean ± standard deviation follow-up 5.2 ± 1.7 years; range 2.2 to 8.1). Physes were open in 9 knees. The Insall-Salvati ratio was 1.09 ± 0.16, and the Caton-Deschamps index was 1.17 ± 0.15. Preoperatively, 19 patients were noted to have trochlear dysplasia, and TT-TG was 15.3 ± 3.9 mm. Three of 4 knees (16.7%) with non-hardware-related complications had open physes: 3 (12.5%) had recurrent instability, 2 of which underwent subsequent operation, and 1 sustained a patella fracture after a fall, requiring open reduction and internal fixation. The average Insall-Salvati ratio of these 4 patients was 1.21 ± 0.20, Caton-Deschamps index was 1.18 ± 0.17, and TT-TG was 17.5 ± 3.3 mm, none of which were statistically different from the group without complications. There were no clinically noted growth disturbances postoperatively. MPFL reconstruction using allograft tissue may be performed safely in the pediatric and adolescent population with good outcomes at midterm follow-up, few complications, and a low rate of recurrent instability. IV, case series.

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

Background: Medial patellofemoral ligament (MPFL) reconstruction is a common surgical treatment for patients with recurrent patellar instability. A variety of risk factors, such as age, trochlear dysplasia, patella alta, and increased tibial tubercle–trochlear groove (TT-TG) distance, have been identified and may lead to postoperative failure or poor outcomes. Purpose: While a large number of risk factors have been identified, significant heterogeneity exists in evaluating and reporting these risk factors in the literature. The goal of this study was to perform a systematic review to determine risk factors associated with worse outcomes after MPFL reconstruction and their consistency of being controlled for or analyzed among studies. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic review of the literature was performed using the MEDLINE database to identify relevant clinical outcome studies after MPFL reconstruction for recurrent patellar instability. Eligible studies were evaluated for risk factors that were associated with MPFL failure, defined as recurrent instability or lack of improvement on patient-reported outcome (PRO) scores. Each study was then evaluated for inclusion of these risk factors. Results: Ten studies were included in the final analysis, comprising 1287 knees from 1275 patients who underwent isolated MPFL reconstruction. Of these 10 studies, 8 defined outcomes based on PROs and 3 defined outcomes based on postoperative recurrent instability (1 study included both outcomes). In the PRO failure group, 12 risk factors were found across all studies: trochlear dysplasia, trochlear bump height, elevated TT-TG, patellar tilt, hyperlaxity, age at first dislocation, age at surgery, body mass index, bilateral symptoms, WARPS/STAID score (weak atraumatic, risky anatomy, pain, and subluxation/strong, traumatic, anatomy normal, instability, and dislocation), femoral tunnel malposition, and femoral tunnel widening. In the recurrent instability failure group, 7 risk factors were found across all studies: trochlear dysplasia, bump height, patella alta, higher sulcus angle, higher congruence angle, preoperative J sign, and femoral tunnel malposition. Trochlear dysplasia and femoral tunnel malposition were consistently cited in several studies as risk factors for worse PROs and higher rates of recurrent instability. Patella alta was indicated as a significant risk factor for recurrent instability in 1 of 2 studies analyzing postoperative instability failures and was not associated with worse PROs in any of the studies analyzed. Similarly, elevated TT-TG distance was not a significant risk factor in any of the studies that analyzed recurrent instability as the failure endpoint. Conclusion: While various risk factors are postulated to affect outcomes after MPFL reconstruction, there remains inconsistency within the literature regarding the inclusion of all risk factors in a given analysis. Furthermore, the significance of these risk factors varies among studies in terms of whether they affect postoperative outcomes. We found that more severe trochlear dysplasia (types C and D) and femoral tunnel malposition (>10 mm from Schöttle’s point) appear to have the most consistent effect on producing higher rates of recurrent dislocation as well as worse PROs. Despite this, the role of concomitant bony procedures to adjust certain pathoanatomic risk factors in addition to MPFL reconstruction remains unknown. Future high-level studies must be conducted that respect the multifactorial nature of patellar instability and should analyze all risk factors (demographic, anatomic, and radiographic) reported to affect outcomes.

Outcomes of MPFL Reconstruction Utilizing a Quadriceps Turndown Technique in the Adolescent/Pediatric Population.

Recurrent instability following a lateral patellar dislocation is a common indication for surgical intervention. Several surgical procedures are described in the literature to address recurrent patellar instability. Medial patellofemoral ligament (MPFL) reconstruction utilizing the quadriceps turndown technique attempts to restore medial stability. Results of the quadriceps turndown technique have previously only been reported in adult populations. The purpose of this study was to assess the safety, efficacy, and patient-reported outcomes following a quadriceps turndown MPFL reconstruction in the pediatric and adolescent population. Records of all patients who underwent MPFL reconstruction using a quadriceps turndown technique between 2011 and 2018 were reviewed for demographics, risk factors, complications, mechanism of injury, and concomitant procedures. Return to activities of daily living (ADLs), return to presurgery level of sport, length of bracing, and recurrent instability were assessed with the administration of the Kujala Anterior Knee Pain Score. All analyses were completed using IBM SPSS Statistics 26. Thirty-six knees [14 female (39%), 22 male (61%)] from 34 patients met inclusion/exclusion criteria. The average follow-up length was 35.9±15.2 months. The average age was 16.3±1.8 years at the time of surgery. The average time for resumption of ADLs was 8.1±6.0 weeks after surgery. Ninety-four percent of patients returned to preinjury level of sport at an average of 23.6±12.0 weeks after surgery. Mean Kujala Anterior Knee Pain Score was 90.7±10.3. Female patients (P<0.001) reported significantly lower Kujala scores. Three patients (8%) experienced recurrent instability during ADLs and an additional 4 (11%) reported subjective feelings of instability only during sport or elevated activity. One knee required a return to the operating room for irrigation and debridement due to infection. This study demonstrates that the quadriceps turndown technique for MPFL reconstruction is a safe and effective procedure for the management of recurrent patellar instability in pediatric and adolescent patients. Level III-therapeutic.

MPFL Reconstruction, 3 Years After the Goldthwait Patellar Tendon Hemi-transfer and Vastus Medialis Oblique Advancement, Performed to Treat Recurrent Patellar Instability: A Case Report

The treatment of patellar instability in skeletally immature patients is challenging for an orthopedic surgeon. We report a case of a 14 years old girl who after an acute traumatic dislocation of the left patella and the failed initial conservative treatment underwent medial patellofemoral ligament (MPFL) reconstruction, using the fascia lata as an autograft. At the age of 10, the Roux-Goldthwait patellar tendon hemi-transfer combined with lateral retinacular release and the advancement of the vastus medialis oblique was performed for the treatment of the recurrent patella dislocation of both her knees. The patient evaluated for re-dislocation risk factors using the patellar instability severity score proposed by Balcarek et al. The clinical evaluation of the patient included the modified Cincinnati rating system and the Kujala score. The imaging assessment included knee MRI for the identification of anatomical risk factors. The four anatomical risk factors, trochlear dysplasia, increased tibial tubercle to trochlea groove offset, patella alta, and patellar tilting > 20°, were identified on MRI. At the final follow-up, the mean modified Cincinnati score increased from 49 to 90 points 6 years postoperatively. The mean Kujala scores increased from 49 to 91 points postoperatively. The MPFL reconstruction is an effective treatment to restore patellar stability in skeletally immature patients who underwent less successful surgeries to treat a recurrent patella dislocation.

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 Reconstruction Using Quadriceps Tendon Autograft, Tibial Tubercle Osteotomy, and Sulcus-Deepening Trochleoplasty for Patellar Instability

Recurrent patellar dislocations have been correlated with an elevated risk of further patellar dislocations, often requiring surgical treatment. Risk factors include medial patellofemoral ligament (MPFL) tears, patella alta, trochlear dysplasia, and an increased tibial tubercle–trochlear groove distance. Surgical management must be based on a patient’s unique joint pathoanatomy and may require MPFL reconstruction with tibial tubercle osteotomy or trochleoplasty either alone or in combination. This article discusses our preferred technique for surgical treatment of recurrent patellar instability with MPFL reconstruction using a quadriceps tendon autograft, an open trochleoplasty, and a tibial tubercle osteotomy for patients with patella alta, trochlear dysplasia, and an increased tibial tubercle–trochlear groove distance.

Does femoral anteversion and internally rotated gait correlate in subjects with patellofemoral instability?

BackgroundPatellar instability is a considerable problem that leads to pain and anxiety during simple functional tasks. Femoral derotational osteotomy has become a common surgical procedure to improve patella mechanics, stability and loading. However, it remains unclear if static (MRI measured) femoral anteversion is sufficient to capture the dynamic femoral rotation during walking and represents a good indication for the surgical procedure. This research investigates the relationship between static femoral anteversion and internally rotated gait in adolescents with patellofemoral instability. MethodsThis retrospective study included 30 adolescents with recurrent patella instability (minimum three patella dislocations) aged 12 to 18 years (28 female/2 male; 22 unilateral/8 bilateral). All participants were assessed with 3D gait analysis and the femoral anteversion was examined using a rotational MRI. Multiple kinematic parameter were correlated with the ipsilateral femoral anteversion and tibia torsion using the Pearson coefficient. FindingsThe correlation between parameters of dynamic hip rotation (e.g. maximum and mean internal hip rotation in stance and swing) and MRI measured femoral anteversion (mean 26.5° ± 9°) was weak and did not reach statistical significance. We found 47% (14 out of 30) subjects with increased femoral anteversion but normal hip rotation in stance. InterpretationThere was no relationship between increased femoral anteversion and dynamic hip rotation. Consequently, femoral anteversion should not be used as the only indication for femoral derotational osteotomy. Three-dimensional gait analysis might be necessary to assess the appropriate surgical intervention in adolescents with patello femoral instability.

Functional outcomes of paediatric medial patellofemoral ligament (MPFL) reconstruction surgery with or without patella distalisation and medialisation for recurrent patella instability

BackgroundNo studies to date have compared the outcome of isolated medial patellofemoral ligament reconstruction (MPFLR) surgery with MPFLR plus re-alignment procedures (MPFLR+) in the paediatric population, making it unclear when additional re-alignment procedures are required.By retrospectively reviewing and comparing our MPFLR patient cohorts’ we aim to generate guidance to aid surgical planning. MethodsUniversity of Salford ethical approval was secured and theatre records were retrospectively reviewed, identifying all patients less than 18 years-of-age who received MPFLR surgery between October 01, 2015 and October 01, 2019.All patients were contacted for documented consent. Pre-operative and post-operative outcome questionnaires were reviewed in conjunction with patient’s medical records and radiological imaging. ResultsA total of 75 MPFLR surgeries were identified and 33 patients (40 knees) consented for inclusion in the study; 23 MPFLR and 17 MPFLR+. Mean improvement in outcome scores achieved statistical significance (P < 0.05) in almost all questionnaire subtypes for both groups. A greater improvement in Quality of life (QoL) correlated with an increased tibial tuberosity–trochlear groove distance (TT-TG) in the MPFLR group 0.557 (P = 0.025) and a lower Patellotrochlear index (PTI) - 0.549 (P = 0.034) in the MPFLR + group.Increased Body Mass Index (BMI) correlated with worse outcomes in numerous questionnaire subtypes (P = 0.05 and P = 0.01) for the MPFLR + group.Increased Trochlear dysplasia correlated – 0.541 (P = 0.03) with less improvement in symptoms following MPFLR + surgery and an increased need for revision surgery 0.312 (P = 0.053) in both groups. ConclusionsBoth groups achieved good outcomes and statistically significant improvements in almost all mean outcome scores following MPFLR surgery, suggesting that our current described selection criteria are appropriate. While we were unable to identify any absolute radiological cut off figures in this diverse population with changing anatomy, we recommend additional procedures be considered for high TT-TG distances and or significant patella alta.Patients with a high BMI should be supported in losing weight prior to surgery and patients with trochlear dysplasia need counselling with regard to potential lesser improvements in symptoms, a higher risk of failure and need for revision surgery. Additional realignment procedures did not appear to offer any improved outcome in the presence of trochlear dysplasia.Level of Evidence IV: Case series.

Predicting Risk of Recurrent Patellofemoral Instability With Measurements of Extensor Mechanism Containment

Background: Identifying risk factors for recurrent patellar dislocation after a primary dislocation may help guide initial treatment. Magnetic resonance imaging (MRI) measurements relating the alignment of the extensor mechanism to trochlear morphology have been shown to distinguish patients with dislocations from controls, but their usefulness in predicting the risk of a second dislocation is not known. Purpose: To identify the association of novel MRI measures of patellar containment with recurrent instability in pediatric patients presenting with a first-time patellar dislocation. Study Design: Cohort study (Prognosis); Level of evidence, 3. Methods: The study was conducted at a tertiary care children’s hospital (2005-2014) on patients (age, 8-19 years) with a first-time patellar dislocation. MRI measurements were made by 2 independent raters. Interobserver reliability was assessed for all measurements via an intraclass correlation coefficient (ICC). Only measurements with an ICC >0.8 were included. Univariable and multivariable logistic regression analyses were used to evaluate variables associated with recurrence. Results: A total of 165 patients with a median age of 14 years and a slight (57.6%) female predominance was identified. The median follow-up length of the whole cohort was 12.2 months (interquartile range, 1.6-37.1 months). Subsequent instability was documented in 98 patients (59.4%). MRI measurements with excellent correlation (ICC > 0.8) were the tibial tubercle to trochlear groove distance (TT-TG), the tangential axial width of the patella, the tangential axial trochlear width, the axial width of the patellar tendon beyond the lateral trochlear ridge (LTR), and the tibial tubercle to LTR distance. In univariate analysis, all mentioned MRI measurements had significant association with recurrent instability. However, after both backward and forward stepwise regression analyses, the tibial tubercle to LTR distance was the only independent predictor of recurrent instability (P = .003 in both). Patients with a tibial tubercle to LTR distance value greater than –1 mm had a significantly higher rate of recurrent patellar dislocation (72%). Conclusion: Of numerous axial view MRI parameters, only the tibial tubercle to LTR distance demonstrated a statistically significant association with recurrent patellar instability upon multivariable logistic regression analysis during short-term follow-up of a pediatric population presenting with initial lateral patellar dislocation. Interobserver correlation of the tibial tubercle to LTR distance was good (ICC > 0.8) and similar to that of TT-TG.