exerts a lot of frictional pressure on the cartilage on both the head of the femur and the hip socket into which it fits. So instead of swiveling smoothly, the two can start to grind painfully, like a pestle in a mortar. Well into the 1950s, there wasn’t much medical science could do to relieve the problem. Complications from hip surgery were so great that the usual procedure was to “fuse” the hip, an operation that relieved the pain but left the person with a permanently stiffened leg. Surgical relief was always short-lived because every
