Medial patellofemoral ligament reconstruction is superior to active rehabilitation in protecting against further patella dislocations

Abstract

Purpose: Isolated reconstruction of the medial patellofemoral ligament (MPFL-R) has become the predominant stabilizing procedure in the treatment of recurrent lateral patellar dislocation (LPD). To minimize the risk of re-dislocations, isolated MPFL-R is recommended in patients with no significant trochlea dysplasia and tibial tuberosity trochlear groove distance < 20 mm on computed tomography (CT). Incidentally, these criteria are the same that are used to identify first time LPD patients where conservative treatment is recommended. The purpose of this study was therefore to compare MPFL-R with active rehabilitation for patients with recurrent LPD (RLPD) in absence of the above mentioned underlying anatomical high-risk factors for further patellar dislocations.

Methods: RLPD-patients aged 12-30 without underlying anatomical high-risk factors for further LPD were randomized into treatment either with isolated MPFL-R or active rehabilitation provided and instructed by a physiotherapist. All patients underwent diagnostic arthroscopy for concomitant problems. The main outcome measure was persistent patellar instability at 12 months. Knee function at baseline and 12 months was asses using the following patient reported outcomes measures (PROMS); KOOS, Kujala, Cincinnati knee rating, Lysholm score and Noyes sports activity rating scale.

Results: Between 2010 and 2019, 61 patients were included in the study (MPFL-R, N = 30, Controls, N = 31). Persistent patellar instability at 12 months was reported by 13 (41.9%) controls, versus 2 (6.7%) in the MPFL-group (RR 6.3 (95% CI 1.5-25.5). No statistically significant differences in activity level were found between the MPFL-group and the Controls at neither baseline nor follow up. The patients with persistent instability at 12 months did not score significantly lower on any of the PROMs compared to their stable peers, regardless of study group.

Conclusion: Patients with recurrent patellar dislocations have a six-fold increased risk of persistent patellar instability if treated with active rehabilitation alone, compared to MPFL-R in combination with active rehabilitation, even in the absence of significant anatomical risk factors. Active rehabilitation of the knee without MPFL-R improves patient reported knee function after one year, but does not protect against persistent patellar instability.

Keywords: Active rehabilitation; Adolescence; Conservative treatment; Functional outcome; MPFL reconstruction; Medial patellofemoral ligament reconstruction; Patellar dislocation.

Conflict of interest statement

None of the authors report any conflict of interest.

© 2022. The Author(s).

Figures

Fig. 1

Schematic drawing of the medial patella femoral ligament reconstruction technique modified from Deie et al. [8]. The ST (semitendinosus) graft is left fixed at the tibia insertion, flipped under the adductor tendon and weaved into the periosteum of the patella at 30 degrees of knee flexion. MCL medial collateral ligament, AT adductor tendon, MPFL medial patellofemoral ligament, P patella, VMO vastus medialis oblique

Fig. 2

Flow chart of patient selection, randomization and follow up

Fig. 3

Mean PROMs results (error bars = confidence interval) for the MPFL-R group and Control group at baseline and 12 months follow up (F12). Maximum score for all PROMs was 100 (Excellent function). All improvements from baseline to follow up were significant (paired t test, p < 0.05), but no significant differences between the two groups were found