There is often a question of how long it’s safe to postpone PAO surgery during the early stages of hip dysplasia in adolescents and adults. Sometimes there’s a labral tear that is tempting to repair with arthroscopy in the hopes of postponing PAO surgery. However, arthroscopic repair does not correct the shallow socket that caused the labral tear in the first place. (click here to view the IHDI arthroscopy statement). PAO surgery is a pretty big surgery that is currently the best way to re-shape the socket and support the hip better. Mild pain from hip dysplasia can often be tolerated or managed instead of proceeding directly to major surgery like the PAO, but waiting too long may increase the chances of needing a total hip replacement. Now, there’s some new research that sheds some light on waiting or not.
A study about waiting or proceeding with PAO surgery was published in a May 2019, issue of the prestigious Journal of Bone and Joint Surgery. https://www.ncbi.nlm.nih.gov/pubmed/31094985 This study was unique because it looked at all stages of arthritis caused by hip dysplasia and compared the patients who had PAO surgery to those who had not undergone PAO surgery. The period of follow-up was as long as 20 years for both groups.
It’s not too surprising that the PAO surgery performed earlier made the biggest difference in avoiding total hip replacement. However, there were some interesting details. The benefits of PAO surgery were less pronounced when there was only dysplasia without any thinning of the cartilage space and no signs of early arthritis on x-ray. However, as soon as the earliest signs of arthritis showed up – mild thinning of the joint space, or small bone spurs – then PAO surgery had the greatest benefit. This was stage 1 of arthritis by the Tönnis classification. Patients who avoided surgery at this stage had more than twice the risk of total hip replacement within ten years. The benefit of PAO surgery was present for Stage 2 of arthritis – moderate joint space thinning, presence of cysts, and moderate loss of roundness of the hip. However, approximately half of these people needed total hip replacement within 10 years compared to three fourths of people who had not undergone PAO surgery. Advanced arthritis in the presence of hip dysplasia only helped for a short period of time and by ten years, 93% of PAO patients had a total hip replacement compared to all the patients who avoided PAO surgery.
What this seems to say is that it may be OK to wait at first if there’s no sign of any arthritis on the x-ray, but as soon as the first sign of arthritis is visible on x-ray, then the PAO surgery has the most benefit. After the arthritis has gotten a little worse, then PAO surgery can help but not as much as when it’s performed during the early stage of arthritis. The people who can safely consider postponing PAO surgery for a little while are those who are discovered to have a shallow socket when they don’t have much pain, and there is no visible arthritis on regular x-rays.