Everyday clinical practice frequently leads us to suspect a close relationship between the lumbar spine and the hip-joints. Sagittal balance fundamentally expresses a postural strategy mobilizing the dynamic structure of the lumbar-pelvic-femoral complex in an authentic balance by which obligatory coupled movements transmit stresses in a single structure, the spine, to the two-part structure of the lower limbs, and vice-versa. Flexion contracture is a frequent hip pathology, but congenital dislocation and ankylosis of the hip have the greatest impact on the spine, due to excessive mechanical strain and/or spinal malalignment, which is initially supple but becomes fixed. Clinical analysis, backed up if necessary by infiltration tests and imaging, guides indications for surgical management. These considerations suggest a general attitude that considers not just the hip itself, for which the patient is consulting, but the lumbar-pelvic-femoral complex as a whole (and also the knee) before undertaking total hip replacement. Femoro-acetabular impingement is a recently described pathology associating morphological hip-joint abnormality and labral and joint cartilage lesions, leading to early osteoarthritis of the hip. Abnormal spinal or pelvic parameters have not been found associated with femoro-acetabular impingement. Congenital pelvic tilt is a benign and often overlooked pathology in children. Supra- and infra-pelvic pelvic tilt in childhood palsy raises the difficult strategic issue of how to get these children in their wheelchair with a well-balanced spine over a straight pelvis and frontally and sagittally balanced hips.