Overview of Knee Osteotomy

An Alternative to Total Knee Replacement Surgery

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Knee osteotomy is a surgery that can be performed instead of a total knee replacement to correct the weight-bearing forces in an unbalanced knee joint. But it is only the right choice for specific patients.

In patients with degenerative arthritis, or osteoarthritis, of the knee joint, deformities of the knee are common. These deformities include a bowlegged or knock-kneed appearance. More technically, these deformities are called genu varum (bowlegged) or genu valgum (knock-kneed). Some studies suggest that if a person already has one of these deformities, their risk of developing osteoarthritis may be higher than in those who do not.

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

As arthritis progresses, the cartilage of the affected joint wears thin, including the meniscus or joint cushions, two wedge-shaped pieces of cartilage. If the damage is worse on one side of the joint than the other, as is usually the case, then the knee will become deformed. When the inside (medial side) of the joint is worn thin, a varus deformity will result. When the outside (lateral side) of the joint wears thin, a valgus deformity results.

What Is the Problem with This Type of Deformity?

When a knee is experiences greater wear on one side, the forces transmitted across the joint are altered. When the medial side wears thin, 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 outside of the joint 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?

An osteotomy is not the best option for every patient with osteoarthritis of the knee. Knee replacement surgery, both partial (PKR) and total (TKR) has been very successful in many patients with this condition. Unless a provider sees a good reason not to perform a replacement, a TKR is usually favored, especially for older patients and those with more advanced osteoarthritis. Some patients, however, including those who are younger and those with osteoarthritis limited to only one compartment of the knee, tend to be better candidates for osteotomy. Because knee replacements wear out over time, younger patients are usually evaluated to see whether alternative procedures would bring greater success.

The ideal patient for a knee osteotomy is younger than 60 years, has a body mass index (BMI) lower than 30, and has arthritis limited to one side of the knee joint. The patient should be able to fully straighten the knee and bend it at least 90 degrees. An ideal patient must also have significant pain and disability to warrant surgery, and must understand that rehabilitation after this surgery is lengthy and difficult. Finally, osteotomies around the knee tend to be effective up to ten years, after which another procedure—usually a knee replacement—needs to be performed. Some patients find lasting relief with an osteotomy, but the majority will have a knee osteotomy as a means to delay eventual knee replacement surgery.

Good candidates for this surgery must fit the following criteria:

  • Significant pain and disability
  • X-rays showing the involvement of only one side of the knee joint
  • The ability to participate in physical therapy and rehabilitation

Who Is Not a Good Candidate for a Knee Osteotomy?

An osteotomy performed on the wrong patient will have a poor outcome. You should discuss with your doctor the potential risks of this type of surgery. Although many people want to avoid knee replacement surgery, the knee osteotomy is not right for every patient.

In general, you should not consider this surgery if you have:

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

How is an Osteotomy Done?

In an osteotomy, the surgeon cuts the high end of the tibia (shinbone) and then reorients it. 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; and an opening wedge, in which the bone is gapped open on one side to realign the bone. Which procedure your surgeon chooses depends on the type of deformity and the location of the osteotomy.

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 has been cut and needs time to heal. You may be able to resume normal activities from three to six months after 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, it is not uncommon for patients to require conversion to knee replacement within a few years of an osteotomy procedure.

Orthopedic surgeons also face the problem of performing an osteotomy in a manner that will not make a possible knee replacement surgery more difficult. It's important to find a doctor experienced in this 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?

With the right patients, knee osteotomies are usually successful at decreasing pain caused by arthritis. More than 80% of patients can return to their normal daily routines after a year. Scientific studies put the ten-year success rate anywhere 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.

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Article Sources

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