STUDY DESIGN: The influence of the pathologic state of the hip joint on the total sagittal alignment of the spine was investigated in patients with congenital hip dislocation retrospectively OBJECTIVE: The purpose of this study was to analyze the total sagittal alignment of the spine and the clinical symptoms in patients with bilateral congenital hip dislocation. SUMMARY OF BACKGROUND OF DATA: Abnormality in the hip joint causes abnormal curvature of the sagittal alignment of the spine and induces lumbago or lower leg pain. However, there have been no reports on the influence of bilateral congenital hip dislocation on the sagittal alignment of the spine. MATERIALS AND METHODS: A total of 9 patients (8 females and 1 male) were analyzed. Their average age was 57 years (range, 46-68 years). We measured the thoracic kyphosis (T1-T12), the lumbar lordosis (L1-S), the sacral inclination (SI), the femoral flexion angle (FFA), pelvic angulation (PA), and the distances from the pelvic hip axis (HA) to the C7 plumb line and from the promontorium to the C7 plumb line. To evaluate clinical symptoms, we used the Japanese Orthopedic Association (JOA) score of low back pain (full score is 29 points) and Visual Analog Scale (VAS) for lower back pain and lower leg pain, and the possible time of walking without rest. RESULTS: The average thoracic kyphosis, lumbar lordosis, SI, and PA were 42 degrees , -78 degrees , 68 degrees , and 27 degrees , respectively. The FFA averaged 10 degrees , leading to a duck-like posture. The distances from HA and, promontorium to the C7 plumb line averaged -2 cm and 4 cm, respectively. A posterior shift of the gravity line with respects to the hips was compensated for by lumbar hyperlordosis, which led to a posterior shift of the center of the spine. Regarding the clinical symptoms, the JOA score averaged 20 points and the VAS for lower back pain (lumbago) and lower leg pain averaged 6.4 and 3.1, respectively. The average possible walking time without rest was 20 minutes. CONCLUSION: The total sagittal alignment of the spine in patients with bilateral hip dislocation was compensated for by anterior angulation of the pelvis and by lumbar hyperlordosis. The main clinical symptoms were lower back pain, and not lower leg pain.