Even though half a million knee replacements are done each year in the United States, there are other treatment options for some patients. If one side of the joint has worn down from problems with alignment, an osteotomy is one possible alternative choice. In this review article, the uses and types of osteotomies available are presented. The authors also discuss when to perform an osteotomy and when to avoid using this technique.
What’s an osteotomy? Basically, an osteotomy is a surgical procedure whereby a bone is cut to shorten, lengthen, or change its alignment. Around the knee, it’s the tibia (the lower leg bone) that is involved. The various kinds of osteotomies are often named for their location. The two most basic types are opening wedge and closing wedge osteotomies.
When is an osteotomy a good idea? The purpose of the osteotomy is to shift the patient’s body weight off the damaged area to the other side of the knee. This makes better use of the cartilage that is still healthy.
The surgeon removes a wedge of the tibia from the healthy side of the knee. It might be taken from the inside (medial) of the tibia (meaning the side of the knee closest to the other knee). That’s an opening wedge osteotomy or medial opening wedge HTO. HTO refers to high tibial osteotomy meaning the wedge is removed right at the upper end of the tibia just under the knee joint.
A closing wedge osteotomy (also known as a lateral closing wedge HTO) takes the piece from the lateral tibia and allows the remaining edges of bone to collapse toward each other to close the gap. Once the wedge is removed, the bones are brought together and held in place with a metal plate or pins.
Whether it’s an opening or closing wedge procedure, an osteotomy allows the tibia and femur to bend away from the damaged cartilage. A tibial osteotomy can enable younger, active osteoarthritis patients to continue using the healthy portion of their knee. The procedure can delay the need for a total knee replacement for up to ten years.
There are some advantages and disadvantages to the osteotomy approach to unilateral (one-side of the joint) arthritis. As mentioned, it can help patients put off joint replacement. And unlike joint implants, with an osteotomy, it’s still possible to engage in high-impact activities like jumping and running.
The disadvantage is that there is a risk of continued knee pain. It’s a trade-off: with osteotomy, there is a greater activity level but more discomfort. With a joint replacement, the pain is gone (or very minimal) but limited activity.
Patients recover faster from a closing wedge procedure since there’s no need for bone grafting. There are fewer potential complications and patients walk (bear weight) sooner after a closing wedge osteotomy.
Opening wedge osteotomies major disadvantage is the fact that the open space has to be filled in with bone graft. It takes longer to heal and there can be pain at the donor site if the patient uses his or her own bone. But the opening wedge procedure has one advantage the closing wedge doesn’t — it allows the surgeon to make precise changes in the angle of the bone, which, in turn, directly affects the alignment of the joint.
More and more surgeons are using computer navigation to give the most accurate realignment possible. Injuries to the nerves and blood vessels in and around the knee can also be avoided with arthroscopic computer navigation. Bleeding into the muscles along the front of the leg can cause a potentially serious condition called anterior compartment syndrome.
There are some complications from osteotomies that can’t be prevented by using arthroscopic or computer navigated technique. For example, sometimes there is a loss of correction before the osteotomy even heals. Once it’s cut into, the bone can fracture with either an opening or a closing wedge procedure. Infection, blood clots (deep vein thrombosis or DVT), and failure to heal are other possible post-operative problems.
Today, osteotomy as a procedure has expanded in its uses and combined with other joint sparing techniques like cartilage preservation, soft tissue reconstruction, and meniscal transplantation. Anyone who is a candidate for these other procedures who also has some alignment problems can have a realignment osteotomy done.
Studies have shown improved results when surgeons look for and treat knee malalignment along with these other procedures. Placing the knee in neutral alignment, reducing alignment deformities, and restoring the weight-bearing axis through the center of the knee is the final goal. The use of osteotomy to correct leg alignment will continue to increase as surgeons treat ligament-deficient, unstable knees before signs of arthritis develop.