Preventing Leg Length Discrepancy and Instability After Total Hip Arthroplasty.

Restoration of equal leg lengths and dynamic hip stability are essential elements of a successful total hip arthroplasty. A careful clinical examination, a preoperative plan, and appropriate intraoperative techniques are necessary to achieve these goals. Preoperative identification of patients at risk for residual leg length discrepancy allows surgeons to adjust the surgical approach and/or the type of implant and provide better preoperative patient education. The use of larger femoral heads, high-offset stem options, and enhanced soft-tissue repairs have improved impingement-free range of motion as well as dynamic hip stability and have contributed to an overall reduction in dislocation. Methods for accurate leg length restoration and component positioning include anatomic landmarks, intraoperative radiographs, intraoperative calipers, stability testing, and computer-assisted surgery. If recurrent instability occurs after total hip arthroplasty, the underlying cause for dislocation should be identified and treated; this may include the use of semiconstrained dual-mobility or fully constrained liners, depending on abductor function. Surgeons should be aware of the clinical and surgical techniques for achieving leg length equalization and dynamic hip stability in total hip arthroplasty.