What is hip impingement? The concept sounds scary enough. A bone spur is slowly damaging the joint cartilage and thus it needs to be removed surgically. However, is this the whole story?
A recent study published last year really questioned the wisdom of this hip arthroscopy procedure. It found that pincer hip impingement (a bone spur on the socket of the ball and socket hip joint), wasn’t associated with the hip getting more arthritis, but less arthritis! In fact, the formation of the bone spur seemed to protect the joint over time. This got me thinking about ways to relay this message to patients.
First, a bone spur forms because the body detects that it needs to shore up the area. This can be due to instability in a joint and the spur is the body’s attempt at stabilizing the joint. It can also happen because of forces going where they shouldn’t. This is common in hips and knees. The video above shows that small changes in how the foot/ankle hit the ground or in knee stability can cause large issues in the part of the hip joint that has to absorb that shock. In the case illustrated, a slight inward movement of the knee results in forces hitting the outside of the hip where there is no joint. The body then grows an extension of the joint to compensate. This is why the bone spur (the extension of that joint) is so helpful. It forms to handle those forces and thus protects the joint from further arthritis. So is whacking it off surgically a good idea? Not so much. While there may be a few instances where this accomplishes a short term goal (like a figure skater who needs an extra 10 degrees of leg out and above the head motion), it doesn’t seem to be a good idea.
The upshot? Removing a bone spur that’s helping to protect the joint is likely not a good idea. We also don’t have any high level evidence saying this helps patients. So why has this become common surgical practice? Your guess is as good as mine!