Femur osteotomy – Knee wedge surgery
Femoral osteotomy—a wedge procedure on the knee—is the name of a surgical procedure performed on the femur itself to correct a misalignment in your leg. It is most often performed just above the knee. By angling the femur a few degrees, the load can be shifted away from the side of the knee that is worn out and causing pain. When the load is shifted from the sore side of the knee to the healthy side, the pain is significantly reduced. (This page does not cover “derotation osteotomy.”)
Femur osteotomy – Knee wedge surgery
Why undergo a wedge resection at all instead of just getting a new knee? The answer is simple. It’s always better to preserve your own knee, if possible. For one thing, about 20% of people who get new knees aren’t satisfied, and for another, knee replacements don’t last forever. A wedge osteotomy may be a better alternative. However, femoral osteotomy is not as common as tibial osteotomy, which you can read more about here. In wedge osteotomy, misalignments are corrected; in rarer cases, the misalignment is in the femur rather than the tibia, and in those cases, the wedge osteotomy is therefore performed on the femur. This is called a femoral osteotomy. The wedge surgery is performed by sawing a wedge into the femur to straighten the leg and fixing it with a splint that is attached with screws. This splint must remain in place until the bone has healed properly. Typically, however, the splint is left in place for ½-1 year. It is often necessary to remove the plate as it is a nuisance.
What is an osteotomy?
In an osteotomy, a bone is cut completely or partially to correct a misalignment. When performed on the femur, it is called a femoral osteotomy. Once the misalignment has been corrected, the bone is stabilized with a splint secured with screws. This splint must remain in place until the bone has healed properly. Typically, however, the splint is left in place for ½–1 year. It is often necessary to remove the splint because it causes discomfort.
Femur osteotomy – Knee wedge surgery is a joint-preserving surgery
Femurosteotomy—a wedge resection of the knee—is what’s known as a joint-preserving surgery. This means a surgery in which no part of the knee is removed. In a wedge resection, a wedge is either inserted into or removed from the femur. The deciding factor is primarily whether you have bowlegs or knock-knees. If you have osteoarthritis (as it is called today), you essentially have thinning of the cartilage. Cartilage is the lubricating layer that covers the bone. Your cartilage has been worn down due to the misalignment, but this can also be caused by other, partly unknown factors. Osteoarthritis affects the inner femur and/or tibia in bow-legged people. And outer femur and/or tibial tuberosity in knocked knees. If you’re up for it and curious, you can read more about knee osteoarthritis here.
Why have I never heard of wedge surgery?
I’m often asked that question, and it’s really sad. The reality is that many Danish orthopedic surgeons don’t really have experience with it and didn’t learn it during their training, so general practitioners don’t really have any experience with it either. So in Denmark, we don’t really have a tradition of performing these wedge osteotomies, but they’re very common in the rest of the world. There is a wealth of scientific evidence supporting osteotomies. Joint replacement surgeons have learned to perform joint replacements, and sports surgeons have learned to perform arthroscopic surgeries, but not many have learned to perform osteotomies.
The principle behind wedge surgery
By far the most common is osteoarthritis on the inside of the knee. That’s why there’s pain on the inside. This is usually because you are bow-legged. This can be remedied with a tibial osteotomy. It’s the other way around if the osteoarthritis is on the outside and you’re a calf knee. Wedge surgery corrects the angle in your knee. This is done by inserting a wedge into the bone at the top of the tibia. This causes the load in your knee to shift to the healthy side of your knee.
On the left, you can see a classic example of a wedge osteotomy of the femur—a so-called femoral osteotomy. This patient underwent surgery for a torn lateral meniscus and received a new cruciate ligament. She continued to experience pain on the outer side of her knee. She had a knock-knee deformity. This meant there was too much stress on the outer side. The image was taken one month after the osteotomy surgery. An incision was made into the outer side of the femur, and the bone was opened up. This created a wedge, which will fill in over time as bone grows into the wedge. The splint holds everything in place. If the splint causes discomfort, it can be removed during a minor procedure 6–12 months later. This patient made a full recovery.
Read more in general about osteotomies on the Tibiaostetomy page.
Femoral osteotomies are more rare than tibial osteotomies and the technique is slightly different. It doesn’t hurt quite as much. You’ll be allowed to quietly support right away. No outer splint/bandage is used either.
Local anesthesia and pain
During the surgery, I place a local anesthetic in your surgical field, which lasts for a few hours. Typically, the anesthesiologist will also place an additional nerve block. This means that the power in your thigh muscle is greatly reduced and typically doesn’t return until the following day. This means that you really need to be careful not to try to support yourself on the operated leg as long as there is no force, because you risk falling and breaking your leg. Unfortunately, this has happened to one patient!
Smoking
A special issue with this surgery is that you must stop smoking at least 2 weeks before and at least 4 weeks after. If you don’t stop, there is a high risk that the bone will not heal.
Complications
Inflammation may occur after the procedure. It happens very rarely, but is serious and needs to be treated. In rare cases, the osteotomy does not heal and needs to be operated on again.
To the right and left are examples of osteoarthritic changes on the outside of the knee. The reason is that in both cases there is a fairly pronounced calf knee in the left knee. The image on the left is a so-called long leg standing measurement where the patient is standing up. Here you can see the hip, knee and ankles.
The image on the right is an MRI scan image of a left knee from the front. On the outside, cartilage thinning and so-called bonebruise can be seen in both the outer femoral and tibial bones. Bonebruise is increased fluid formation and is often seen with the onset of osteoarthritis.
It should perhaps be added that both patients were treated successfully and returned to running.
