Objectives : Muscle imbalance poses a problem for adequate motor function in patients with cerebral palsy. The adductor and flexor muscles around the hip become dominant, leading to a high risk of hip dislocation. When left untreated, flexion and adduction contracture progresses, leading to various impairments ; hence, it is important to undertake preventive measures at an early stage. Selective muscle release is one form of surgical treatment that has been proven effective, but there is no consensus on the timing of the surgery. Here, we investigated the difference in outcome after muscle release surgery with respect to age. Subjects and methods : The subjects were 26 patients (52 hips) from our medical center who underwent muscle release (partial modification of Matsuo's method) around the hip and were followed up for at least 6 months. Abduction was retained postoperatively by using a cast or prosthetic device. Migration percentage (MP) was measured by simple hip radiography image, and the rates of improvement (preoperative MP . final MP during observation/preoperative MP ×100%) were compared. Results : Higher rates of improvement were observed among patients aged 5 years or less at the time of surgery than those among patients aged 6 years or more. Conclusion : We consider that surgery performed at the age of 5 years or less could lead to favorable results.

Introduction : We examined the characteristics of paralytic scoliosis using plain radiography.Subjects and methods : We recruited fourteen patients aged ≥ 15 years old with no history of bone surgery at the time of their final observation. Participants included those who had cerebral palsy or those who had a history of encephalitis and underwent spinal frontal plain radiography in the supine position at different time points. We evaluated gross motor function, position and direction of the curve, Cobb angle, rate of variability, and degree of progression at 5-year intervals. We measured the percentage of migration using hip frontal plain radiography to assess hip dislocation.Results : The final Cobb angles were 82.0°, 118.4°, and 92.3°for the thoracic, thoracolumbar (TL), and lumbar curvatures, respectively. TL curvatures showed the greatest progression, although this was not statistically significant. The progression was greatest in the 10-15-year age group (12.5°annually). The final Cobb angles in the hip dislocation, subluxation, and no dislocation groups were 102.8°, 108.8°, and 87.5°, respectively；the difference was not statistically significant. No relationship was observed between the location or progression of curvature and the state of the hip location.Discussion : Paralytic scoliosis progressed most rapidly in 10-15-year-old patients, especially in those with TL lesions. We did not detect any relationships between hip dislocation and Cobb angle, but these parameters progressed at different rates in different patients.