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9/6/2005 12:40:44 PM - Where are the bionics?
A few years ago I had surgery performed on my left knee. Decades of playing soccer on the hard, uneven fields of Texas had apparently taken their toll.
The doctor had told me that I had a "Grade 4" defect...as it was explained to me, there are only four grades, and the higher the number the worse the problem. In my case, I had worn the cartilage away entirely in one area...in others, the cartilage had been fractured so much that it looked like a bomb had exploded.
Given that cartilage does not regenerate, this was obviously a huge problem. It meant that I often had bone touching bone whereas normally the cartilage would act as a sort of shock absorber to minimize the stress upon impact. That was causing pain, swelling, and various other problems. Playing soccer became impossible and I had to curtail all sorts of other physical activities.
That doctor recommended a procedure known as "microfracture". I read about it and wasn't impressed. The basic operation would involve clearing out the loose cartilage fragments and smoothing out the remainder. The doctor would then drill into the bone and cause it to bleed. That blood would then harden and form a type of weaker, softer "fibrous cartilage."
The long-term success rate of this procedure varies depending on a variety of parameters, but it's rarely a good solution for someone with significant cartilage damage.
When my right knee began to develop problems, I began hunting for something more technically advanced than microfracture. My father mentioned that he had heard of a company called Genzyme that could regrow cartilage for reimplantation. After checking into it further, I became convinced that "autologous chondrocyte implantation" (ACI) was a much more viable long-term solution.
Most orthopaedic surgeons aren't yet able to perform this surgery, but I managed to find a surgeon in Austin that had a significant amount of experience with it.
An initial arthroscopic examination (wherein the doctor is able to use thin tools to minimize the intrusion to the affected area) is typically performed to ensure that the patient is a viable candidate for the procedure. The defects have to be of a certain size, be surrounded by good cartilage, and meet various other requirements. Assuming these criteria are met, the doctor would then extract a small sample of your own cartilage from a non-load-bearing area. That sample would then be sent to Genzyme where it would be cultured and grown into a fluid-like substance.
A subsequent (non-arthroscopic, so it's much more invasive) surgery then has the doctor making two incisions. The first and smaller one is (in my case) near the top of the shin bone. A section of the bone's periosteum is shaved away to serve as a cap. A larger incision is then made over the knee itself. In my case, the defect lay in the trochlear groove so the doctor needed to use a clamp to hold the kneecap away during the procedure so that he could get to the area with the problem.
Any damaged articular cartilage near the affected area is drilled away in order to leave a clear path to the bone. The hole is then capped with the section of extracted periosteum and sutured to the neighboring good cartilage. The suturing process is complex enough that special training is required before a surgeon is allowed to perform the procedure.
Typically, the periosteum cap is placed over the defect and sutures are then sewn every 2 millimeters along the circumference. The sutures are linked into the neighboring good cartilage (which is, again, one of the pre-requisites for this particular procedure.) I had a 2.5 centimeter defect - about an inch in diameter - and that therefore required roughly 70-80 sutures. A small area is left unsutured so that the fluid from Genzyme (which contains the cells that will grow into your replacement cartilage) will be able to be inserted. Biological glue is then placed over the sutures to provide an even tighter seal. Saline solution is inserted into the defect (via the small, unsutured area) to ensure that the seal is tight enough to keep the cells in place over the months they will take to harden. When the surgeon is satisfied that the area is properly sealed, the fluid from Genzyme is inserted, the last small area is sutured shut, and biological glue is then used to seal it as well.
In theory, the inserted fluid should harden into actual cartilage that is as tough and durable as regular cartilage. The periosteum cap serves to keep the fluid in place until it attaches to the neighboring cartilage and hardens. That process takes about a year and is one of the reasons why the doctors will tell you that you should not over-exert yourself during the 12-18 month rehabilitation phase. If you dislodge the cap before the fluid has had a chance to mature, you will significantly reduce the likelihood of a successful procedure.
I just completed the implantation process and have been connected to a passive motion machine for the last several days (meaning that it simply bends my knee without any physical effort on my part.) I'll post more on how this procedure seems to be going as I experience it.
For now, here are some pictures...
Here's the knee before the implantation procedure...it's always a bit swollen nowadays because of the aggravation caused by the hole in the cartilage.
Getting ready for the implantation...
Removing the bandages...
The whole knee area - and even the upper leg - is pretty swollen two and a half days after surgery...
A side shot to show off some more of the swelling...and the staples.
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