It’s Probably Over for Bo : Prognosis: Expert says the replacement parts won’t be able to stand the stress of most pro athletics.

Hip replacement surgery, the procedure Bo Jackson apparently has chosen to treat a crippling injury, probably won’t leave the two-sport star in position to continue to play baseball and football competitively, specialists say.

The surgery is relatively unusual in younger patients, whose activity levels can strain the replacement parts. Those who do have the operation while young are advised to avoid high-impact activities that could shorten the artificial joint’s life span.

“In general, for the type of activities that a high-quality athlete does, these operations are not designed to return them to a competitive level,” said Gerald Finerman, acting chiefof orthopedic surgery at UCLA Medical Center.

“The forces placed upon a prosthetic joint--for example in football--would be enormous,” added Finerman, who is also director of sports medicine at UCLA. “It would not hold up for a significant length of time in those activities.”

However, Finerman conceded that some patients might choose to run the risk of jeopardizing the new joint. In such a case, he said, a professional athlete, having recovered, might be able to continue in baseball as a designated hitter.

Jackson’s hip was injured in January of 1991 while he was playing for the Raiders. The blood supply to the injured area was disrupted, causing severe deterioration of the cartilage that serves as a cushion between the hip socket and thigh bone.

Hip replacement is common, with what Finerman estimated to be perhaps 100,000 done each year. It is done most often in those whose joints have been damaged by osteoarthritis or rheumatoid arthritis.

In the operation, the surgeon removes the head of the thigh bone--or femur--and implants a cup-shaped socket into the pelvis. An artificial ball and shaft are attached to the femur; the ball is placed in the artificial socket, and the muscles and tendons are reattached.

The joint, made of metal and plastic, might remain unstable for several weeks after the operation. According to the American Medical Assn., during that period, patients are advised to sleep on their backs and not cross their legs, and are taught how to get in and out of the bathtub without disrupting the joint.

Recovery from the operation usually takes about three months. But it might take up to six months to regain full strength and to return to moderate activity levels.

According to Finerman, who performs the operation, most patients regain their ability to walk and conduct what he called “normal . . . activities.” For example, he said that some can play golf and limited amounts of tennis, “but not at the levels that (a professional) athlete would require.”

Younger patients pose particular problems because of their higher activity levels and the need for the joint to last, ideally, for the rest of their lives. For that reason, Finerman said, a surgeon might recommend an even greater restriction of activity for a younger patient than for an older one.