The Procedure:  Refrigerated Femoral Condyle Transplant James D. Bruckner, M.D., and associate professor of orthopaedics at the University of Washington performed the refrigerated femoral condyle transplant on Mat Martin. He explains the surgery here for RESOURCE.

When a portion of the knee joint is damaged by trauma, we have a number of ways to address the injury. If the cartilage is irreparably damaged, however, there are few good surgical options for restoring it. Cartilage does not heal well by itself; a full thickness defect in the femoral condyle requires “scar cartilage” to heal but it lacks the lubrication characteristics of normal joint cartilage. Then you have pain like Mat did.

One solution is mosaicplasty – transplanting cartilage plugs from other parts of the joint. The resulting “mosaic” of small round plugs fills the defect but is less than ideal because of the gaps between them and the small but real defects created where the plugs used to be.

As an alternative, we can recover allograft knee joints – distal femurs in this case – with cartilage on them. Through the Northwest Tissue Services, we’ve developed a protocol to store these allografts in such a way as to increase the number of cartilage cells that survive storage and transplant.

That involves not freezing them although freezing is the standard. Instead, the Tissue Services refrigerates them in a nutrient solution, until donor screening and testing is done and the allograft can be safely transplanted, typically about four weeks. So now, with a safe allograft rather than an autograft, we can repair essentially any size defect in bone and cartilage of a traumatized knee joint.

I usually affix the grafts with bio-absorbable pins. They’re 1.5 mm pins made of the same material as the sutures – they’re rigid but they dissolve.

COMPLICATIONS
We always worry about infection and in a major knee operation, there’s possible muscle weakness and scarring. We also worry that the cartilage graft won’t survive – that the cartilage on top of the graft will deteriorate. In the 3 1/2 years I’ve done this surgery, that’s not happened.

There’s not really a rejection problem for this type of graft because knee cartilage is relatively protected from the immune environment because it gets its nutrition from synovial fluid rather than blood.

So we don’t do tissue matching; we match size, which is a more critical issue. The geometry of the condyle of the knee is very complex. It’s not flat; it has an arc of curvature in two planes from front to back and the shape is irregular. So it’s more important to match the radius and curvature of the condyle.

REHABILITATION
The operation requires tremendous patient investment: three months on crutches including using a motion machine eight hours a day for the first six weeks. Full rehabilitation takes about nine months to get full weight-bearing and most muscle strength back.

Overall, patients have done quite well with this procedure. I saw Mat in March and he’s also doing fine with respect to his graft.