Bones and Cartilage

The xrays I took in July 2008 (right) show the faulty structure of my hips. Notice how the hip socket does not cup the femoral head on either side of body -- the sockets are shallow and thus all the upward, weight-bearing force of my femur slams right into the very edges of my hip sockets. You can see that the space there is much narrower than the space between the ball and socket in the rest of the joint. That is because I have spent 29 years pounding away at the cushioning of my hip joint in that one spot.

Dr. Su noted that my right hip is worse than my left, and therefore would need surgery before my left hip. One can see from the xray that more of my left femoral head ("ball" of hip) is inside the socket than my right. (In the xray, my right hip is on the left side of the film, as if you were looking at me standing in front of you.)

The next step was to ensure that I had enough cartilage left in my right hip to perform a successful PAO. If I'd worn away too much cartilage, even a PAO wouldn't necessarily keep me from having to have a total hip replacement relatively soon. Damaged cartilage has a limited ability to repair itself, and is very slow to repair. For this reason, humans suffer arthritis from a lifetime of wearing down the cartilage in their joints; if cartilage could quickly and effectively repair itself, arthritis would not be so prevalent. If I didn't have enough left to cushion the joint even after it had been reconstructed into the correct alignment, the PAO would not be an appropriate surgery. It would be too late.

Ideally, a dysplastic (dysplasia-afflicted) patient has a PAO -- reconstructing the natural joint -- rather than a hip replacement -- replacing the natural joint with a prosthetic joint. It is preferable to keep the natural joint since the body has the ability to dynamically maintain the health and function of the natural joint throughout life, whereas a prosthetic joint will wear out like any mechanical device and need to be replaced. A natural human joint generates less friction than even the most perfect ball bearing; in other words, we have never invented an equal substitute for a natural joint. Cartilage has not even been recreated in a lab yet, not via stem cells nor via synthetic materials. A prosthetic hip can only be expected to last 10 to 15 years in someone with my age and activity level, meaning the prosthetic would have to be surgically replaced one or more times over my lifetime. Clearly, one PAO in each hip now is preferable to several hip replacement surgeries for each hip over my lifetime.

On October 17, I had an MRI focusing on my right hip. An MRI is much more effective at showing the soft tissue of the body, and therefore could show the amount and state of my cartilage, as well as the other soft tissues in and around my joint, such as ligaments, tendons and musculature. It is worth reading the description of the MRI linked above -- I never really knew how the technology worked or why the machine had to make all that clunking throughout the procedure.

The MRI experience itself was not terribly scary if you don't mind napping in a farrier's shed. The scan took about an hour, with no physical effects other than an odd tingling from time to time. The lab had special MRI-compatible headphones so I could listen to the music of my choice during the scan. The clunking managed to drown out The Doors from time to time, but having music was better than listening to my thoughts.

On October 21, I went to Dr. Su's office for the MRI results. I was pretty worried that I might not have enough cartilage and would not be able to have the PAO in the right hip, but would instead have to have a replacement. As I discussed above, that was not the preferred option. My anxiety was fueled by the fact that my right hip had been hurting almost constantly since my xray-follow-up appointment earlier in the month -- it certainly didn't feel like there was enough cartilage in there!

Thankfully, there was. Dr. Su said I had a good amount of cartilage, but that it was beginning to "fibrillate," meaning soften and weaken, the early stages of arthritis. This just underscored the need to have the surgery as soon as possible.

My MRI report also explained why I felt so much pain in the front of my hip socket. There is a ring of cartilage called the acetabluar labrum that surrounds the lip of the hip socket, like an o-ring. Its function is to deepen the hip socket, keeping the head of the femur from popping out of the socket. Given my shallow hip sockets, it makes sense that my labrum was being put under intense strain holding my hip joints together.

The MRI report read: "The anterior [front of the body] labrum is chronically torn and degenerated, appearing hyperplastic [enlarged, stretched] and generating ganglion cysts [fluid-filled cysts caused by repetitive wear on the joint] that dissect outside the confines of the fibrocartilage, deep [into] the iliopsoas muscle-tendon junction." This means the cysts are intruding into the muscle-tendon junction of my iliopsoas, a muscle triad that are the strongest of the hip flexor muscles. This is causing "mild insertional iliopsoas tendinosis without tear," meaning degeneration without inflammation but damage to the tendon on a cellular level.

In short: ouch.