Normalisation of Patella Alta with MPFL Reconstruction Reduces the Prevalence of Risk Factors Associated With Recurrent Patella Dislocations - A Prospective Cross Sectional Study
Background: Patella alta is a well-established risk factor for recurrent lateral patella dislocations. Medial patellofemoral ligament (MPFL) reconstruction has been shown to consistently reduce patella height. Our hypothesis is that MPFL reconstruction reduces the number of risk factors for recurrent dislocations through the correction of patella alta, resulting in a decreased risk of recurrence.Methods: A prospective cross-sectional case series of 33 knees which underwent MPFL reconstruction
... FL reconstruction for lateral patella dislocations. Information on patellar height utilising the Insall-Salvati (IS) and Caton-Deschamps (CD) ratios, Tibial Tuberosity–Trochlear Groove (TT-TG) distance, trochlear dysplasia, and outcome scores were recorded pre-operatively and post-operatively. The mean change in patella height and the number of knees which achieved normalisation of patella alta were determined. Student's paired samples T-tests were used to compare the differences in the means scores of the groups pre-operatively and post-operatively. The McNemar test for paired categorical data was used to compare the number of the patella alta corrected after MPFL reconstruction. A pre-determined significance of alpha level of 0.05 was used.Results: The mean age of 33 patients included in the study was 21.5 years (range, 16 – 34 years). There was statistically significant reduction in patella height between pre-operative and post-operative measurements using the various patella height indices for all patients (p<0.001), and normalisation of patella alta (CD ≥1.3) for 90% of patients post-operatively (p<0.004). One third of patients 33.3% had at least 3 risk factors pre-operatively. This was reduced to 18.2% after MPFL reconstruction, representing a 45.5% decrease. A statistically significant improvement in the outcome scores was found – Kujala score 57.1 ± 14.1 pre-operatively to 94.8 ± 5.1 post-operatively (p<0.0001). The recurrent dislocation rate was 3.0%.Conclusion: MPFL reconstruction for lateral patella dislocation results in a statistically significant improvement in clinical outcomes and decrease in patellar height ratios. Normalisation of abnormal patella height culminated in the reduction of anatomical risk factors associated with recurrent dislocations.