Purpose

First-time lateral patellar dislocation (LPD) is a common injury in physically active adolescents and may lead to recurrent LPD. Management for first-time traumatic LPD is controversial. Surgical management may result in a lower risk for recurrent LPD, though majority of first-time dislocators are suitable for nonoperative management. There is no consensus about the most preferable method for nonoperative treatment after first-time LPD. Main purpose of this study was to evaluate the efficacy of patellar stabilizing, motion restricting knee brace vs non-hinged sham brace in non-operative treatment for first-time LPD. Primary outcome was patellar redislocation rate in a three-year follow-up.

Methods

101 skeletally mature patients with first-time traumatic LPD were enrolled to the study. After verification for the diagnosis by MRI, nine patients were excluded because of concomitant injury in affected knee. Additional ten patients were excluded because of primary MPFL reconstruction or surgical repair of osteochondral fracture was performed, based on discretion by the surgeon. Eventually 79 patients with first-time traumatic LPD were randomized and allocated to two study groups; group A with patellar stabilizing, motion restricted knee brace (hinged to allow knee range of motion between 0-30 degrees only) and group B with non-hinged sham brace (neoprene sleeve brace not restricting any knee motion, but similar in size than group A brace). Both groups received similar physiotherapeutic instructions and were advised to use the brace continuously for four weeks, after which they were allowed to regain their physical activity freely. 15 patients were lost from the follow-up or failed to use the study brace as supervised and were excluded. Altogether 64 patients completed the trial.

Results

For primary outcome measure, the reported LPD redislocation rate in group A (restricted ROM brace) was 11 out of 32 patients (34.4%) and 12 out of 32 patients (37.5%) in group B (sham brace) (p=0.794). Patients in group B (sham brace) had better knee ROM than patients in group A (restricted ROM brace) at four weeks (115 vs. 90 degrees, p=0.000) and at 3 months (133 vs 125 degrees, p=0.028). At six-month follow-up no difference was seen. Patients in group B (sham brace) had less quadriceps muscle atrophy than patients in group A (restricted ROM brace) at four weeks (16/32 vs. 24/32, p=0.048) and at 3 months (16/32 vs. 24/32, p=0.048). At six month follow-up patients in group B (sham brace) reported better functional outcome than patients in group A (restricted ROM brace) (Kujala score 93.6 vs. 89.0, mean difference 4.6, p=0.012), though no difference was found at three years.

Conclusions

According to this randomized controlled study, motion restricting patellar stabilizing brace for four weeks after first-time traumatic LPD does not decrease redislocation rate in a three-year follow-up. More importantly, knee immobilization has harmful effect on knee function, presented as more quadriceps muscle atrophy, slower regain of knee range of motion and lower functional outcome.