As you’ve pointed out osteopetrosis is a rare condition. Not much is known about the treatment of osteoarthritis in older adults with this problem. In fact there have only been about a dozen cases reported.
Doctors from the Mayo Clinic recently presented the results of five cases of osteopetrosis and joint replacement. They also reviewed the results of seven other cases previously reported.
The most recent cases all had a good result. Three were hip replacements and two were knee replacements. There were no major problems after the operations. Patients were followed for up to 20 years.
The surgeons point out that the operation takes longer in patients with osteopetrosis. The bone is dense and must be cut with special instruments. Often the bone marrow canal is missing. This is where the stem of the implant goes. The surgeon must cut a canal in the bone for the implant.
All in all these cases show that patients with osteopetrosis can have a successful joint replacement. If you are thinking about having this done, you may want to consider going to the Mayo Clinic where the surgeons have experience with this special problem.