Abstract
Objectives:
Lateral patellar instability is a debilitating condition not only to athletes, but also a broad range of highly active individuals. Many of these patients experience instability symptoms bilaterally. Medial patellofemoral ligament reconstruction (MPFLR) is indicated to prevent future recurrence and ideally facilitate a complete return to sports (RTS). While RTS has been examined following MPFLR, the rate and timing of RTS in patients that undergo MPFLR bilaterally is unknown. The purpose of this study is to compare patients who have received bilateral MPFLR to a matched unilateral cohort, to elucidate potential differences and eventually allow better prognostication of this unique population’s ability to return to sports.
Methods:
Patients who underwent primary MPFL reconstructions with minimum 12-months clinical follow-up were identified from a single institution from the years 2011 to 2021. Those who underwent non-simultaneous primary MPFL reconstruction of bilateral knees were identified, as well as cohort of unilateral MPFLR. Surveys were then disseminated, including the Visual Analog Scale (VAS) for pain and satisfaction, the Kujala Anterior Knee Pain Scale, the Tegner Activity Scale, and the MPFL-RSI assessing psychological readiness to RTS. Detailed baseline sport activity and RTS information was collected, which was modified for bilateral patients to report on each procedure. For analysis, bilateral and unilateral MPFLRs were matched in a 1:2 ratio based on age, sex, BMI, and status of concomitant tibial tubercle osteotomy (TTO). A sub-analysis was performed comparing patients who underwent concomitant TTO compared to isolated MPFLR. Outcomes were compared between cohorts using T-tests and Chi-square analyses when required. Bivariate linear regression and logistic regression were performed to assess correlation between RTS and outcome scores, as well as psychological readiness.
Results:
Surveys were completed by 24 patients who underwent bilateral MPFL reconstruction and 105 unilateral patients with a total mean follow-up time of 4.2 ± 2.4 years. Among the bilateral patients, average time between MPFL procedures was 19.3 ± 16.9 months; notably, 71.4% of patients had symptoms in the contralateral knee at the time of index procedure. Three bilateral patients were unable to be matched, resulting in a 21:42 match with respective bilateral and unilateral cohorts having a mean age (22.5 ± 5.7 vs 23.3 ± 6.6 years; p = 0.65), sex (males 9/21 vs 18/42; p = 1.00), BMI (25.87 ± 6.39 vs 25.21 ± 4.78 kg/m2; p = 0.65), and concomitant TTO (9/18 vs 18/42; p = 1.00) that did not significantly differ, indicating successful matching. When comparing matched cohorts, bilateral MPFLR patients returned-to-sport at a similar rate to unilaterals following both their first (61.1% vs 63.2%; p = 0.98) and second MPFLR (72.7% vs 63.2%; p = 0.82). After undergoing both procedures, 33.3% of the bilateral cohort was able to return to their preinjury level of sport, compared to 26.3% of unilaterals (p = 0.82). The mean time for bilateral patient to RTS following their first procedure was 24.3 ± 7.5 weeks and 22.5 ± 12.9 weeks after their second, compared to the unilateral time-to-return taking 38.5 ± 23.0 weeks, though this difference at each time point (bilateral index vs unilateral; bilateral contralateral vs unilateral) did not reach significance (p = 0.06; p = 0.08). All patients scored highly with respect to VAS surgery satisfaction (85.4 vs 82.8; p = 0.44). There were no significant differences found between bilateral and unilateral cohorts for the Kulaja score (79.0 vs 86.1; p = 0.14) or in psychological readiness to RTS as indicated by the MPFL-RSI (49.7 ± 24.2 vs 58.8 ± 26.7; p = 0.24). Regression analysis found both the Kujala score (β = 0.06, p = 0.01) and MPFL-RSI (β = 0.06, p < 0.01) to be weakly, but significantly associated with rate of RTS. Sub-analysis of MPFLR with and without concomitant TTO did not demonstrate any significant differences with respect to RTS, psychological readiness, or any other outcome score (p > 0.05).
Conclusions:
The results of this study suggest that patients who undergo MPFLR bilaterally are able to return to sports at a similar rate and to a similar level compared to a matched unilateral comparison group with equivalent satisfaction and functional outcome scores. These findings are particularly important due to the high prevalence of simultaneous bilateral symptomatic patellar instability. With no demonstrable differences in rate and timing of return-to-sport, knee function, and psychological readiness between patients who have undergone unilateral versus bilateral MPFLR, surgeons can more confidently report equivalent outcomes to patients particularly with respect to RTS rates.