Evaluation of preoperative hip range of motion under general anaesthesia

Hip range of motion (ROM) may be an important preoperative variable, however, measurement of hip ROM can be affected by various factors. The purposes of this study were to compare conventional preoperative ROM measurements with those measurements obtained under general anaesthesia, and to better define the associations between preoperative hip ROM, and demographic, functional, and diagnostic variables. Conventional preoperative hip ROM and ROM under general anaesthesia were prospectively measured in 471 hips. Harris pain score, the Crowe classification, and the diagnosis were also investigated. The hip ROM in all directions under general anaesthesia was significantly greater than conventional preoperative hip ROM. There were correlations between conventional preoperative hip ROM and the Harris hip pain score. Hip ROM with Crowe type I deformity under anaesthesia was significantly greater than in hips with type II, III or IV. ROM under anaesthesia of osteonecrosis hips was significantly greater than osteoarthritis and dislocated hips. Conventional preoperative ROM in men was greater in flexion and external rotation compared to women. Internal rotation motion in women in both conventional preoperative ROM and ROM under anaesthesia was greater than in men. Hip pain, Crowe classification and diagnosis could influence preoperative hip ROM. Measurement of hip ROM under general anaesthesia could better reflect true ROM compared to measurement without anaesthesia.