Abstract
Aim
The purpose of this study was to analyze the patellofemoral kinematics in neglected adult developmental dysplasia of the hip patients with patellofemoral symptoms and tried to clarify the affect of the severity of dislocation, the amount of limb length discrepancy, the deviation of mechanical axis and the changes in femoral anteversion on patellofemoral alignment.
Methods
The dynamic patellofemoral CT results of 39 patients with DDH suffering from knee pain were reviewed. The mean age was 40.07 (range: 22–61). 14 of them were bilateral and 25 were unilateral neglected DDH patients. The CT results of 12 patients suffering from unilateral patellofemoral pain following the treatment of locked intramedullary nailing was taken as control group. In this patients atraumatic and asymptomatic normal site was taken as control group.
Results
In unilateral neglected DDH patients there was significantly higher medial patellar displacement in 0, 15, 30, 60 degrees flexion in the knee at the site of dislocation. Again in uninvolved site medial patellar displacement in 15, 30, 60 degrees flexion was higher with respect to control group. In the involved extremity the PTA angle in 0, 15, 30, 60 degrees flexion were significantly higher than in control group. This increase in PTA angle corresponding to medial patellar tilt was observed only in involved extremity. In the knees of patients with bilateral DDH there was significant medial patellar displacement in every flexion degrees with respect to control group. Besides in bilateral DDH patients, the PTA angle in 15, 30, 60 degrees flexion were significantly higher than control group corresponding to medial patellar tilt. The amount of leg length discrepancy and the severity of dislocation as well as mechanical axis deviation were not affecting the patellofemoral parameters in both unilateral and bilateral DDH patients.
Conclusion
Both in unilateral and bilateral DDH patients there are major changes in patellar tracking on femur during knee flexion. Increased medial shift and medial patellar tilt were seen in these patient groups. The neglected DDH patients suffering from knee pain should be analyzed not only for tibiofemoral abnormalities but also for patellofemoral malignment.
