Can an Aggressive Knee Surgical Implant Regrow Cartilage?
POSTED ON 9/5/2013 IN Knee BY Christopher Centeno
Can a super brace regrow cartilage? This past few years we've seen a proliferation of knee unloader braces for patients with knee arthritis on one side of the knee. We've used these as part of knee stem cell treatments to keep weight off of the arthritic side and to allow some controlled pressure, but less than the usual amount. However, if you view arthritis as a disease were the wear and tear on joint cartilage outpaces the normal stem cell mediated repair process in the joint, what if you could reduce the wear and tear by much more? Would the normal repair process be enough to regrow cartilage? Well, two small studies published last week and in 2011 would argue that this is exactly what happens. The first was a study performed in the Netherlands in 2011. Twenty patients who were on average 48 years of age with mild to severe arthritis underwent a surgical implant where the device distracted the bones on the arthritic side and produced space between the bones (see torture device above). The patients couldn't bend the knee due to the device, so every two weeks they came back to the hospital to get the device removed for a few hours for range of motion. This wasn't trivial as the device had pins that were drilled into bone and these had to be removed for a few hours and then reimplanted. After two months of this, despite the every two week range of motion drills, the knees were pretty stiff, so the patients were given a machine to range the knee at home and told to build up their muscle strength. What was the result? By one year, pain went down about 2/3rds and function doubled. More interesting was that they gained about 1/3 more joint width (which collapses in arthritis) and MRI analysis showed about 20-25% thicker cartilage. A second follow-up study showed that most of the gains were still there at two years. However, two patients (10%) also had blood clots while wearing the super brace (because they weren't moving their knee) and had to be hospitalized. The upshot? While encouraging, this is a pretty darn invasive way to treat a knee. Having said that it provided an interesting thought experiment that may teach us quite a bit about helping cartilage. For example, the results are consistent with those obtained after high tibial osteotomy where a section of bone is cut out to off load one side of the knee. While new cartilage doesn't grow, the MRI appearance of cartilage gets better. It was disappointing that I couldn't find a similar study with a knee unloader brace to see if taking weight off the damaged side through bracing may have a similar effect. On the con side, the authors really didn't quantify what was produced, so the cartilage quality may not be great. However, it's still fascinating how well the body responded to reduced wear and tear. This again brings up that reducing the extra loading on an area is a critical part of healing. We discuss this further in our e-book Orthopedics 2.0 in the symmetry section.
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