The Effects of Early Range of Motion Versus Immobilization Following Acute First-Time Lateral Patellar Instability Episode: Randomized Control Trial

BACKGROUND: The acute management of lateral patellar dislocations (LPD) typically consists of placing the patient in a knee immobilizer for 2 to 6 weeks, but it is not clear on how long these patients should be immobilized, if at all. HYPOTHESIS/PURPOSE: The purpose of this study is to compare outcomes for patients following a rehabilitation protocol that is initiated with or without a short period of immobilization after sustaining a LPD. METHODS: An IRB-approved prospective study was performed at a children’s hospital which included patients <18 years of age (mean = 14.22) diagnosed with LPD (<10 days). A total of 18 (14 females, 4 males) patients diagnosed with LPD were consented and enrolled in the study (Early ROM group = 11, Immobilization group = 7). Inclusion criteria for the study was history of knee instability, effusion or history of effusion, and (+) apprehension. Subjects were followed for 4 weeks and the following outcomes were assessed: knee ROM, isokinetic strength, Kujala, Pedi-IKDC, and Y balance scores. Split-plot (2x2) ANOVAs were conducted for each of the dependent variables with an alpha level set at .05 for the global tests and independent t-tests were run at baseline and 4 weeks. RESULTS: There were no significant differences between groups at baseline. Knee flexion ROM showed a significant main effect of time (p≤.0005) and group (p=.012). Pedi-IKDC showed a significant main effect of time (p≤.0005) and group (p=.026). When comparing groups at 4 weeks, the early ROM group had significantly better scores in both the Kujala (means for both groups: 76.78 and 52.67), p=.049)), and the Pedi-IKDC (means for both groups: 68.85 and 40.88), p=.025)). There were no significant differences in isokinetic strength measures between the groups except for affected side knee flexion at 60 degrees/sec (p=.039) with the early ROM demonstrating higher strength. In addition, the affected side composite Y-balance scores were significantly better for the early ROM group (as compared to the immobilization group) at p=.031. CONCLUSION: Patients that underwent early ROM following LPD scored significantly better across patient derived outcome measures and functional outcomes at 4 weeks following the initial physical therapy evaluation when compared to a group that underwent a 2 week period of immobilization. Future studies should analyze longer term comparisons between groups to determine if this short term difference leads to long term differences or improved re-injury rates.