Anterior Knee Pain in Patients with Cerebral Palsy

BACKGROUND: The aim of this study was to identify the risk factors for anterior knee pain in patients with cerebral palsy. METHODS: This prospective study investigated the risk factors for anterior knee pain in 127 ambulatory patients with spastic cerebral palsy in terms of walking pain, resting pain, and provocative pain. Demographic data analysis and physical examination for measuring the knee flexion contracture and unilateral and bilateral popliteal angles were performed. Patellar height was measured on radiographs, and patella alta was identified. The risk factors for anterior knee pain were analyzed using multivariate analysis with a generalized estimating equation. RESULTS: Seventy-seven patients were found to have patella alta based on the radiographic measurements (60.6%). Overall, sixteen patients (12.6%) had either unilateral or bilateral anterior knee pain. Of these, 6 patients showed a visual analogue scale (VAS) ≤ 3, 9 patients showed 3 < VAS ≤ 7, and one patient showed a VAS > 7. Age was found to be a significant risk factor for walking pain and resting pain with odds ratios (ORs) of 1.08 (95% confidence interval [CI], 1.02 to 1.14) and 1.09 (95% CI, 1.03 to 1.15), respectively. In the multivariate analysis, knee flexion contracture was a significant protective factor with an OR of 0.92 (95% CI, 0.85 to 0.98). CONCLUSIONS: Approximately 12.6% of ambulatory patients with spastic cerebral palsy were found to have anterior knee pain in our hospital-based cohort study. Age was found to be a significant risk factor for anterior knee pain while walking and resting.