The iliopsoas is considered a major deforming force causing hip flexion deformity in children with cerebral palsy. Although iliopsoas release at the lesser trochanter is thought by many clinicians to cause excessive hip flexor weakness, we believe that it does not produce iatrogenic hip flexion weakness. We were unable to find a study in the literature that objectively studied this issue. Included in the study were 25 patients, all ambulators with cerebral palsy (any type). They underwent iliopsoas release at the lesser trochanter and multiple surgeries (soft tissue with or without bony procedures). Mean age at surgery was 11.4 years.

Motion analysis was performed to all patients prior to surgery and one year post-op. Hip and knee range of motion was improved with out significant decrease in hip flexion power. Maximum hip extension improved, no change in maximum and total flexion power generation was found. As expected, hip range of motion was improved significantly. We proved that when releasing the iliopsoas at the lesser trochanter, the change in power generation is statistically insignificant, as shown by maximum and total hip power generation in swing phase.