Pelvic obliquity. Its causes and its treatment.

Pelvic obliquity can be caused by leg length inequality, contractures about the hips, as part of a structural scoliosis, or as a combination of two or more of these causes. Careful physical and radiologic evaluations are necessary to establish the correct diagnosis. Treatment is then directed toward the specific cause, ie, leg length balancing, release of hip contractures, or scoliosis correction. Structural scolioses with pelvic obliquity may be either congenital or paralytic. If a traction roentgenogram reveals the curve to be flexible enough that the pelvis can be fully leveled, then a posterior fusion only is necessary. If the pelvis will not level with traction, then anterior convex wedge excisions (discectomies for the paralytic, hemivertebra excision for the congenital) are necessary for achieving adequate correction. Posterior instrumentation and fusion must follow the anterior procedure. Various forms of internal correction and fixation devices are now available, and there is no single best procedure. Anterior internal fixation devices are being used less and less, while posterior segmental fixation with Luque rods are wires is being used more and more.