Putting the Problem of Dislocation Following Total Hip Arthroplasty into Perspective by Recalling the Past

When discussing early dislocation following total hip arthroplasty (THA), one must recognize how much the procedure has changed. Sir John Charnley in the 1960s insisted that the procedure be called a “low-friction arthroplasty” and not just a total hip replacement. He instructed his many fellows to view THA as an all-inclusive process, involving preoperative patient expectations, surgical approach and technique, hip biomechanics, implant design and materials, implant fixation, postoperative protocols, rehabilitation, postoperative limitations, and long-term restrictions. All of these elements have changed dramatically over the past 50 years, resulting in a variety of factors contributing to the problem of postoperative dislocation. Dislocation was rare following Charnley’s THA—with 2 exceptions: (1) failed trochanteric fixation and (2) polyethylene wear causing premature impingement. Postoperatively, patients were restricted to bedrest with both legs suspended in mild flexion and abduction. By today’s standards, these were extreme precautions. The problem of early dislocation following THA first became evident to us after reviewing 2 consecutive series of THAs performed at The Hospital for Special Surgery from 1972 to 1978. This was a time of transition from performing the classic Charnley lateral trans-trochanteric THA to the newer and less disruptive posterolateral THA, which allowed surgeons to avoid trochanteric osteotomy. Alarmingly, the incidence of early dislocations jumped from 0% to 7.5%1, and new postoperative restrictions were designed to prevent early postoperative dislocation while pursuing less invasive surgical approaches. Many innovations followed, improving prosthetic hip-joint stability and reducing the risk of postoperative dislocation. These included changes in soft-tissue preservation and repair; increased offset options; improved head-to-neck diameter ratios; variable acetabular component constraints; new materials to reduce wear, allowing larger and more stable femoral heads; and improved knowledge regarding component position. As a result, postoperative precautions were gradually reduced. Still, some remained, such as avoiding lying on the side without a pillow between the knees; using elevated chairs and toilets; requiring crutches for extended periods of time; avoiding hip flexion of >90°; and avoiding combined hip flexion, adduction, and internal rotation. These restrictions have particularly been recommended following THA performed with use of a posterior approach. Klaassen et al. compared the rates of dislocation before and after the discontinuation of strict movement restrictions following THA in patients treated for osteoarthritis. The authors showed that there was no significant difference between cohorts, emphasizing that the additional relaxation of precautions not only improved the patient experience but also helped to reduce the cost of the “all-inclusive process” of THA.