Every coin has two sides. Total knee replacements (TKRs) are a lot like that, too. On one side are the results of advances and improvements over the years. This side shows TKRs as a good and reliable operation for arthritic knees. On the other side are the reports of complications after the operation. These include infection, fracture, blood clots, and loss of muscle control. On more rare occasions this side of the TKR coin also includes heterotropic ossification (HO).
HO is the formation of bone in and around soft tissues such as muscles. HO can develop along the front of the thigh above the knee joint after TKR. But how often does it really happen? And what are its effects? These are the questions Japanese researchers studied. Sixty-three TKRs for rheumatoid and osteoarthritis were included. X-rays were taken before and after the operation to compare the changes in bone.
The researchers were surprised to find HO present in nearly 40 percent of the patients. The changes were seen within four weeks of the operation. However, the changes went away over time for two-thirds of these patients. HO was more common in the patients with osteoarthritis in this study.
The authors suspect one of the reasons HO isn’t seen after TKR has to do with the X-rays. Doctors reading the X-rays are looking for signs of infection or implant loosening. They may not see the small changes in the shadows of the bone that occur with HO.
If a coin could have three sides, here’s what the TKR coin would show. HO after TKR takes care of itself over time. By the end of 12 months, motion in the joint is the same in patients with and without HO. Treatment for the HO may not even be needed.