Hip joint replacements are watched very carefully in patients younger than 50 years old. This is because the implant may not last more than 10 to 15 years. Researchers are keeping track of which implants last the longest and recording the number and type of problems.
Thirteen doctors in several centers pooled their patients to create a larger study group. The first study included about six years of follow-up after the joint was replaced. This second report from the group reports on them after 10 years.
In both studies, information about the patients was gathered. Age, diagnosis, gender, and pain levels were recorded. Use of support during walking, walking distance, and ability to climb stairs were also measured. X-rays were taken, and failure rate was recorded.
The authors report a high rate of wear and loosening of the cup on the socket side of the hip. Almost half of the hips showed signs of failure. Results from other studies are very similar.
Researchers think the cup needs to be redesigned to decrease breakdown of the bone, called osteolysis. Osteolysis and wear on the implant lead to cup loosening. When the cup loosens, a new operation is needed to replace the cup and its liner.
Ongoing research such as this gives doctors and researchers helpful information. In this case, the high rate of hip joint revisions alerted doctors to the need for changes in the implant design. Redesign has already happened, including cups made using highly cross-linked polyethylene. The goal is to decrease polyethylene wear and osteolysis. Results of studies with the same group of patients will be reported at regular intervals in the future.