New, updated techniques used to perform osteotomies make this procedure one to consider for younger, more active patients with unicompartmental knee arthritis. Osteotomy is a surgical procedure designed to realign the knee and even out the weight-bearing forces from side to side. A wedge-shaped piece of bone is removed from one side of the bone. Then the bone above and below the space is adjusted to correct the joint alignment. The two sides of the bone can be held open with a special opening-wedge metal device screwed into the bone. Or the two sides of the bone can be collapsed down toward each other in a closing-wedge procedure.
Once the joint is realigned to create a more normal load distribution, painful symptoms go away, and the knee is stable again. The best use of this procedure is for patients who have abnormal joint alignment and uneven weight-bearing that has led to arthritis on one side of the joint. That's what is meant by unicompartmental (one-sided) knee arthritis. Usually the medial side (or compartment closest to the other knee) is affected but lateral unicompartmental arthritis can develop instead. The type of unicompartmental arthritis that develops is based on how the knee is put together, where the alignment problem is, and how the uneven load affects the joint.
In the past, osteotomies were more commonly used with older adults. But their use in younger adults has become the focus of closer attention in the last few years. That's why orthopedic surgeons wrote this review article from the University of Pennsylvania. They offer surgeons a second look at high tibial and distal femoral osteotomies for young patients with unicompartmental arthritis of the knee. Anyone who is too active, too young (less than 50 years old), and unwilling to protect the total knee replacement by modifying and limiting activities might be a good candidate for an osteotomy.
High tibial osteotomies are done in the upper portion of the tibia (the lower leg bone) -- usually just below the knee joint and above the shaft or long portion of the bone. Distal femoral osteotomy is done along the lower portion of the femur (thigh bone) -- above the knee joint but below the long shaft of the femur. Tibial osteotomies are done much more often than femoral osteotomies.
The surgeon based on X-rays and clinical observations of the bony alignment determines the exact location of the procedure and whether an opening-wedge or closing-wedge approach is used. Full-length hip to ankle X-rays are recommended. MRIs may be ordered to give surgeons a better preoperative idea of the condition of the surrounding soft tissues (ligaments, cartilage, other knee compartments) Each patient is evaluated individually. There's no set formula of X, Y, Z to guide the surgeon.
There are some general guidelines based on the results of studies done so far. For example, anyone who has had the meniscus (knee cartilage) removed from the knee or who has severe degenerative disease on the other side of the joint is not a good candidate for an osteotomy. Osteotomy buys the patient some time before having a total knee replacement. During that interim, activities are not restricted. The person can be as active as he or she would like.