Osteolysis or bone loss after total joint replacement (knee or hip) can be a problem. Tiny flecks of bone and debris from the backside of the implant lead to osteolysis. Over time the implant can come loose or the bone can fracture.
Not everyone with osteolysis has symptoms (pain, swelling, loss of motion), especially early on. The only way to know for sure if there is any bone loss is to take an X-ray. Osteolytic lesions look like someone took a bite out of the bone. But X-rays are only a two-dimensional view of a three-dimensional object. So although they show there is a problem, X-rays aren’t enough to tell the surgeon the full extent of the defect. More advanced imaging (CT scans or MRIs) may be needed.
Routine screening for osteolysis is recommended starting five years after total hip arthroplasty (THA or replacement). Follow-up X-rays are advised every two to three years after that for as long as the patient has the implant. Anyone at risk should be monitored even more closely.
The patients at greatest risk of osteolysis are those who are younger and more active. Men tend to fall into this category more often than women. Because this type of osteolysis is linked with wear debris, it takes time to develop. That’s why routine screening isn’t recommended until five years out. And, of course, as more time passes, the risk increases.
Certain types of implants are more likely to shed metal debris with use. The first ultra-high molecular-weight polyethylene (UHMWPE) implant components (parts) used tend to wear out faster than the newer highly cross-linked UHMWPE implants. So anyone with the conventional UHMWPE should be assessed for sure.
What happens if osteolysis is detected? Well, no immediate treatment is needed. The patient is followed more closely (every four to six months) instead of every two or three years. If there are signs that the lesion is getting larger or worse, then the patient may be a candidate for surgery. Serial (repeated) X-rays shows the rate of progression (how fast and how much worse the osteolysis is developing).
With the newer materials for hip implants, the risk of osteolysis is less. Talk with your surgeon about your concerns for this (and other) potential problem(s). It’s good to be realistic about what to expect but remember, most of the things we worry about never happen.