1Department of Orthopaedic Surgery, Massachusetts General Hos- pital, 5 Longfellow Place, Suite 201, Boston, Massachusetts 02114
2Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
A pressure-measuring Moore-type endoprosthesis was implanted in a seventy-three-year-old patient who had sustained a displaced fracture of the femoral neck. The measurement and telemetry of contact pressures in the hip began in the operating room, and data were acquired periodically for more than thirty-six months. Unexpectedly high localized contact pressures between the acetabular cartilage and the prosthesis were recorded. Early in the period of recovery, activities such as using a bedpan or performing isometric exercise produced pressures that were close to those recorded during normal walking. The highest pressure, eighteen megapascals, was recorded one year postoperatively, while the patient was rising from a chair. High pressures occurred in the superior and posterior aspects of the acetabulum. A pressure-measuring Moore-type endoprosthesis was implanted in a seventy-three-year-old patient who had sustained a displaced fracture of the femoral neck. The measurement and telemetry of contact pressures in the hip began in the operating room, and data were acquired periodically for more than thirty-six months. Unexpectedly high localized contact pressures between the acetabular cartilage and the prosthesis were recorded. Early in the period of recovery, activities such as using a bedpan or performing isometric exercise produced pressures that were close to those recorded during normal walking. The highest pressure, eighteen megapascals, was recorded one year postoperatively, while the patient was rising from a chair. High pressures occurred in the superior and posterior aspects of the acetabulum.
CLINICAL RELEVANCE: We quantified the articular pressures during early and late rehabilitation therapy after replacement of the femoral head. The data indicated that traditional postoperative management and protocols for rehabilitation may not be optimum. The highest pressures were consistently localized to the superior and posterior regions of the acetabulum, corresponding to the sites of degenerative changes in the acetabulum that have been observed in studies on cadavera.