Physical examination

The physical examination was performed at both pre and postoperative gait analysis visits. Knee flexion contracture was defined as not fully extending the knee joint to neutral position (i.e., 0° of knee extension). It was measured, while the child supine, with the hip in full extension and the ankle in plantarflexion, by a goniometer on to the lateral side of the thigh and shank. The hip was always in maximum extension to measure the knee flexion contracture to avoid the influence of the hamstring contracture. Figure 1. The inter-rater reliability for passive knee extension (knee flexion contracture) was 3.5 degrees_. The popliteal angle was measured supine with the hip flexed to 90 degrees, and the knee was extended until the pelvis starts to rotate and at this position, the goniometer measurement was assessed. The hamstring muscle spasticity is measured by the modified Ashworth Scale, a 6-point rating scale for the level of muscle resistance to passive movement [27]. The Gross Motor Function Measure, dimension D (GMFM-D), which is a functional assessment of standing ability developed for children with CP, was evaluated as well as the GMFCS level [6, 28].

Examination position of knee flexion contracture. By using a goniometer on to the lateral side of the thigh and shank

No difference was found in knee flexion contracture (p = 0.375) between the right side (11.0° [SD 8.2]) and left side (10.4° [SD 8.6]) on preoperative physical examination. Results from the right side were used as the representative data of each individual except GMFM-D, which evaluates the bilateral standing function.