Postoperative gait analyses for developmental dislocation of the hip

Objective To explore the gait function of surgical patients with developmental dislocation of the hip (DDH) via a three-dimensional (3D) biomechanical approach. Methods Twenty-two surgical patients of DDH were selected between May 2010 and November 2012. There were 9 males and 13 females with an average age of 5.3 (3-10) years. At 18 months post-operation, they were evaluated by 3D gait motion analysis system (Motion Inc., USA). And three step lengths at a constant gait speed were measured. Fifteen points were selected around pelvis, hip, knee and ankle and connected for acquiring 3D dynamic images. Results Compared with control group, the patient movements of pelvis, hip, knee and ankle were obviously different. In unilateral ones, postoperative pelvic heights were higher than contralateral counterparts and anterior pelvic tilt was slightly insufficient. Postoperative hip had those of less abduction and flexion and more external than those of control group. The postoperative flexion peak for both knees declined during swing phase. The postoperative ipsilateral foot had more internal rotation. Pelvis of triple pelvic osteotomy group was lower than those of Salter and Pemberton groups. And anterior pelvic tilt was worse in Pemberton group than that in Salter group. Walking speed, cadence and step showed no significant difference with normal children. And the extension moment of postoperative hips decreased and capacity declined. Conclusions Walking speed, cadence and step of DDH patients after operation show no significant difference compared with normal controls. However, during whole gait cycle, hip flexion is insufficient; pelvis was lower during weight-bearing period. Moreover, pelvis of triple pelvic osteotomy is lower than those of pemberton and salter groups. Key words: Dislocation of hip joint; Gait analysis; Osteotomy