Abstract:Objective: To investigate the characteristics of functional jump test performance and lower limb muscle strength recovery in patients with patellar dislocation after medial patellofemoral ligament (MPFL) reconstruction, and to analyze the correlation between these parameters and their guiding value for return-to-sport decision-making. Methods: A total of 116 patients with recurrent patellar dislocation who underwent MPFL reconstruction were enrolled as study subjects. The study group was followed up for 12 months postoperatively to compare functional differences between 6 and 12 months after surgery. Functional jumping ability was assessed using the single-leg hop for distance (SLHD), triple hop for distance (THD), crossover hop for distance (CHD), and the 6-meter timed hop (6m-TH) test. Quadriceps and hamstring muscle strength were evaluated using an isokinetic dynamometry system at angular velocities of 60°/s and 180°/s, and the limb symmetry index (LSI) was calculated. The correlation between various functional indicators was analyzed. Results: The LSI values for SLHD, THD, and CHD at 12 months postoperatively were higher than those at 6 months postoperatively (P < 0.05), while the LSI value for 6m-TH was lower at 12 months than at 6 months (P < 0.05). At the 12-month follow-up, the LSI values for quadriceps peak torque at both 60°/s and 180°/s were higher than those at 6 months postoperatively (P < 0.05), and the hamstring LSI values were also higher than those at 6 months (P < 0.05). Using an LSI ≥ 90% on all four hop tests as the criterion for achieving functional symmetry, the rate was 21.55% at 6 months postoperatively and increased to 41.38% at 12 months postoperatively (P < 0.05). At 12 months postoperatively, quadriceps peak torque LSI values (at both 60°/s and 180°/s) showed positive correlations with the LSI values of SLHD, THD, and CHD (P < 0.05). No significant correlations were observed between the affected-side H/Q ratio and the LSI values of SLHD, THD, and CHD (P > 0.05). Conclusion: Functional jumping ability and muscle strength recovery in patients with patellar dislocation after MPFL reconstruction exhibit time-dependent improvement. However, residual deficits in functional jumping performance persist at 12 months postoperatively. Quadriceps strength recovery is closely associated with jumping performance, providing objective evidence for clinical rehabilitation and return-to-sport assessment.