Overview of Knee Osteotomy

Knee osteotomy is a surgical procedure in which structures of the knee are shifted to relieve pressure. You may need this operation to correct the weight-bearing forces of an unbalanced knee joint, which can occur with issues such as bow legs.

Osteoarthritis commonly causes deformities of the knee such as genu varum (bowlegged) or genu valgum (knock-kneed). Some studies suggest that these deformities increase the risk of developing osteoarthritis.

What Causes a Bowlegged or Knock-Kneed Deformity in Arthritis?

As arthritis progresses, the cartilage of the affected joint wears thin. This includes the meniscus or joint cushions, two wedge-shaped pieces of cartilage—located at the outside (lateral side) and inside (medial side) of each knee.

If the damage is worse on one side of the joint than the other, as is usually the case, then the knee can become deformed. When the medial side of the joint is worn thin, a varus deformity will result. When the lateral side of the joint wears thin, a valgus deformity results.

What Is the Problem with This Type of Deformity?

When there's more wear on one side of the knee, the forces transmitted across the joint are altered.

The force of body weight re-centers on the worn part of the joint, so the less damaged part of the knee is spared the burden of body weight and the damaged portion receives the brunt of the body weight. This becomes a cycle that leads to the further progression of arthritis.

How Does an Osteotomy of the Knee Help?

The idea of an osteotomy is to shift the weight-bearing forces so that the worn part of the joint (usually the inside) is under less pressure and the greater weight-bearing force is on the healthier side of the joint.

Who Is an Ideal Candidate for a Knee Osteotomy Surgery?

If you are younger than 60 years old or your osteoarthritis is limited to only one compartment of your knee, an osteotomy might be beneficial for you.

Good candidates for this surgery are typically required to fit the following criteria:

• Significant pain and disability
• Able to fully straighten the knee and bend it at least 90 degrees
• X-rays showing the involvement of only one side of the knee joint
• A body mass index (BMI) lower than 30
• The ability to participate in physical therapy and rehabilitation—rehabilitation after this surgery is lengthy and difficult

You might find lasting relief with an osteotomy, but most people will have a knee osteotomy as a means to delay eventual knee replacement surgery. An osteotomy around the knee is expected to be effective for up to ten years, after which another procedure—usually a knee replacement—might be necessary.

Who Is Not a Good Candidate for a Knee Osteotomy?

Although many people want to avoid knee replacement surgery, knee osteotomy is not right for everyone. An osteotomy is not always the best option for treating knee osteoarthritis and you can have a poor outcome if this procedure isn't right for you.

In general, you should not consider this knee osteotomy if you have:

• Widespread arthritis of your knee (not confined to one side)
• Instability of the knee (tibial subluxation)
• Significant limitations of knee motion
• Inflammatory arthritis (such as rheumatoid arthritis)

Knee replacement surgery, both partial (PKR) and total (TKR), is often very successful. Unless you have a contraindication to the procedure, a TKR is usually favored, especially if you are older or have advanced osteoarthritis.

Because knee replacements wear out over time, if you are younger, alternative procedures would be considered.

How is an Osteotomy Done?

During an osteotomy, your surgeon would cut the high end of your tibia (shinbone) and then reorient it.

Which procedure your surgeon chooses for you depends on the type of deformity of your knee.

The two basic types of osteotomies are:

• A closing wedge, in which a wedge-shaped piece of the bone is removed and the bone is realigned by closing the gap
• An opening wedge, in which the bone is gapped open on one side to realign the bone

Once the bone is cut and subsequently realigned, your surgeon may install a metal plate and screws to hold the bones in their new positions.

How Long Is the Recovery From a Knee Osteotomy?

Recovery from a knee osteotomy can be difficult. A bone is cut during the procedure, and it needs time to heal. You may be able to resume normal activities between three to six months after your surgery. You will need physical therapy to regain full knee motion.

What Are the Complications of Knee Osteotomy Surgery?

The most common problem with this surgery is that it almost always fails over time. Now, if you can feel better for nearly a decade and delay knee replacement surgery, it may be well worth it. However, a knee replacement may be necessary within a few years of an osteotomy procedure.

Other potential, but unlikely, complications include problems with healing (nonunion), injuries to vessels and nerves, continued pain from arthritis, stiffness of the knee joint, blood clots, and infection.

How Successful Is This Surgery?

A knee osteotomy is usually effective for reducing knee pain caused by arthritis. More than 80% of patients can return to their normal daily routines within a year after surgery. Scientific studies put the ten-year success rate between 51% and 93%, including those requiring later TKR surgery.

Because of these results, knee osteotomy is generally reserved for young, active patients who want to delay knee replacement surgery.