J. Koh (Evanston, US)
NorthShore University Health System Department of Orthopaedic SurgeryPresenter Of 1 Presentation
23.1.7 - Tibial tubercle distalization can reduce articular cartilage contact pressures in the patellofemoral joint of patients with patella alta
Abstract
Purpose
Tibial tuberosity distalization with normal patella height increases articular contact pressures; however, it is unknown what is the biomechanical effect of distalization in patients with patella alta. There is concern that distalization in these cases can result in iatrogenic increases in contact pressure. We sought to characterize the effect of distalization on contact pressure in patients with patella alta.
Methods and Materials
High resolution 3T MRI scans of eight patients (1 male, 7 female, mean age 17, range 13-21) being treated for patellar instability were used to create individual multibody dynamic computer simulation models with patella alta (Caton-Deschamps index ≥ 1.3). Dynamic knee squatting was simulated for 3 conditions: the native knee with patella alta; following distalization (Caton-Deschamps index = 1.0); and following distalization combined with patellar tendon tenodesis. Patellofemoral contact pressures and distribution were based on discrete element analysis. Repeated measures comparisons were used to identify significant (p < 0.05) differences between the conditions.
Results
Tuberosity distalization significantly decreased the maximum pressure applied to cartilage at 15°, 20°, 30°, and 35° of flexion, with the decrease more than 20% of the pre-operative pressure. Distalization also significantly increased contact area from 15° to 40° of flexion. Tenodesis had a relatively small influence on the kinematics and pressure, compared to distalization.
Conclusion
Tibial tuberosity distalization is associated with a reduction in peak patella contact pressure at low flexion angles. Distalization may help decrease the risk of patellofemoral arthritis in patients witha alta.