Functional outcome after recurrent patellar dislocation : Comparison of two surgical techniques-Medial patellofemoral ligament reconstruction (MPFL) vs. Elmslie Trillat procedure

Isokinetic Strength Profiles Among Youth after Medial Patellofemoral Ligament Reconstruction

Background

Knee strength is a critical measure of successful rehabilitation following medial patellofemoral ligament reconstruction (MPFLR). Yet, strength outcomes of youth following MPFLR are not widely reported.

Hypothesis/Purpose

The primary purpose was to profile isokinetic strength outcomes by sex and age among youth following MPFLR. A secondary purpose was to determine the relationship between normalized isokinetic strength values and patient-reported outcome scores by age and sex. The hypotheses were that 1) males would demonstrate higher normalized strength, and that 2) a higher proportion of males would achieve ≥90% limb symmetry when compared to females.

Study Design

Cross-sectional.

Methods

At 6.9±2.1 months after MPFLR, 162 patients completed isokinetic assessment of knee extension (KE) and flexion (KF) strength at 180°/s and 300°/s on both limbs (uninvolved [UN], involved [INV]). Strength data and patient-reported outcome scores, including the International Knee Documentation Committee (IKDC) Subjective Knee Form and Pediatric Quality of Life Inventory (PedsQL) were extracted from electronic medical records. Descriptive statistics were used to categorize data by age (Pre-adolescent, Early Adolescent, Late Adolescent, Young Adult) and sex. Independent-samples t-tests and chi-square analyses were used to determine sex-based differences in strength. Multiple linear regression analyses were used to determine the relationship between strength and patient-reported function.

Results

Among Early Adolescents, males demonstrated higher normalized KE strength at 300°/s compared to females (UN: 1.27±0.3 vs. 1.07±0.3 [p=0.01]; INV: 1.07±0.2 vs. 0.92±0.3 [p=0.03]). Among Late Adolescents, males demonstrated higher INV limb strength for KE 180°/s (1.55±0.53 vs. 1.24±0.5; p=0.02), KE 300°/s (1.25±0.4 vs. 1.00±0.4; p=0.01), and KF 180°/s (0.98±0.4 vs. 0.82±0.3; p=0.05). A higher proportion of Late Adolescent and Young Adult males achieved ≥90% LSI compared to females (p=<0.01-0.04). Regression models estimating IKDC and PedsQL scores were significant with INV KE strength as an independent variable (p=0.01-0.03).

Conclusions

Males demonstrated higher normalized strength and symmetry compared to females following MPFLR. Higher INV KE strength was associated with higher patient-reported function.

Level of Evidence

2b.

Is There a Strength Deficit of the Quadriceps Femoris Muscle in Patients Treated Conservatively or Surgically after Primary or Recurrent Patellar Dislocations? A Systematic Review and Meta-Analysis

Background: Patellar dislocation is a knee injury affecting generally young, active individuals, damaging joint ligaments and structures, and impacting sports activity and quality of life. Objective: This review aimed to evaluate the role of the quadriceps femoris muscle in knee extension and to consider whether extensor strength deficits are present in patients who have suffered from a primary or recurrent patellar dislocation and have been treated surgically or conservatively. Methods: This systematic literature review with meta-analysis was performed following the PRISMA Statement criteria. The search engines consulted to select studies were MEDLINE/PubMed, Scopus, and Web of Science/ISI. The JBI Critical Appraisal Checklist tools were applied for the quality assessment based on the specific study design. The outcomes were measurements of the knee extension force of the quadriceps femoris muscle, which were objectively quantifiable with an isokinetic or mobile dynamometer. Results: Of the 891 articles initially identified through the databases, 10 studies with a total of 370 patients were included in the analysis. The results indicated a strength deficit of the quadriceps in patients who had undergone a patellar dislocation, in comparison with the control group, when examining the uninvolved limb or in comparison with the pre-operative values. The overall effect size was large, with a value of -0.99. Conclusions: Our review concluded that after a primary or recurrent patellar dislocation, strength deficits of the quadriceps femoris muscle in the knee extension of the affected limb are frequently observed in surgically or conservatively treated patients. This deficit may persist even after a protracted follow-up of up to three years after injury.

Outcomes and reoperation rates after tibial tubercle transfer and medial patellofemoral ligament reconstruction: higher revision stabilization in patients with trochlear dysplasia and patella alta

PURPOSE

To determine the reoperation rate, risk factors for reoperation, and patient-reported outcomes after isolated or combined tibial tubercle transfer and medial patellofemoral ligament reconstruction, for patellofemoral instability surgery.

METHODS

Patient's records who underwent medial patellofemoral ligament reconstruction and/or tibial tubercle transfer for patellar instability by 35 surgeons from 2002 to 2018 at a single academic institution were retrospectively reviewed using CPT codes. Four-hundred-and-eighty-six patients were identified. Radiographic measurements, demographic parameters, and subsequent revision procedures and their indications were identified. A modified anterior knee pain survey was conducted by mail and with follow-up phone survey.

RESULTS

The overall rate of reoperation was 120/486 (24.7%). The most common cause for reoperation was removal of hardware 42/486 (8.6%). The rate of reoperation for isolated medial patellofemoral ligament reconstruction 43/226 (19%) was lower than that of isolated tibial tubercle transfer 45/133 (33.8%) or a combined procedure 32/127 (25.2%) (P = 0.007). Woman had a higher rate of reoperation (29.4%) compared to men (15.9%) (P = 0.002). Patients at risk for a revision stabilization procedure included those with severe trochlear morphology (C or D) (6.1%) and those with Caton-Deschamps index > 1.3 (7.3%). Patients who underwent reoperation of any kind had poorer patient-reported outcomes.

CONCLUSION

The overall reoperation rate after patellofemoral instability surgery remains high, and any reoperation portends worse patient-reported outcomes. Re-operations for instability are more likely in patients with trochlear dysplasia and patella alta and may benefit from more aggressive initial treatment, such as medial patellofemoral ligament reconstruction and tibial tubercle transfer in combination. Using the results of this study, surgeons will be able to engage in meaningful discussion with patients to counsel patients on expectations postoperatively.

LEVEL OF EVIDENCE

IV.

Objectively quantified lower limb strength recovery in people treated surgically or non-surgically after patellar dislocation: A systematic review

OBJECTIVE

Synthesize evidence on objectively quantified lower limb strength recovery in people treated surgically or non-surgically after patellar dislocation.

METHODS

MEDLINE, EMBASE, Cochrane Library, SPORTDiscus, PEDro, AMED and CINAHL databases were last searched on July 30th, 2020 for randomized controlled trials and observational studies that objectively quantified lower limb strength in people (any age or sex) treated surgically or non-surgically after patellar dislocation.

RESULTS

24 studies were included (877 participants, median age 20.7). All assessed knee extension strength, 11 knee flexion strength, three hip abduction strength, two hip external rotation strength, and one hip flexion, extension, adduction, and internal rotation strength. One randomized controlled trial judged at high risk of bias and two cohort studies with methodological limitations compared lower limb strength recovery between surgically and non-surgically treated people, with conflicting findings. After surgery, median long-term (>8 months) knee extension strength was 82.5% (IQR 78.5-88.2; 13 studies) of the unaffected leg and knee flexion strength was 91.5% (IQR 90.7-96.9; five studies). After non-surgical treatment, median long-term knee extension strength was 86% (IQR 79.3-87.4; four studies) and mean flexion strength ranged from 95.2 to 96.7% (two studies). Mean hip strength was always >90% (two studies). Two redislocations during eccentric isokinetic knee testing and knee pain during isokinetic knee extension testing were reported as adverse events.

CONCLUSIONS

Available evidence indicates that after patellar dislocation, knee extension strength deficits in the affected limb are frequently observed and can persist long term, but this remains uncertain due to the limitations of relevant included studies. Whether lower limb strength recovery differs between people treated surgically and those treated non-surgically after patellar dislocation also remains uncertain.

TRIAL REGISTRATION

(PROSPERO CRD42019139533).