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.