Knee Osteotomy

Alternative to Total Knee Replacement Surgery for Some Arthritis Patients

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 bow-legged or knock-kneed appearance. More technically, these deformities are called genu varum (bow-legged) or genu valgum (knock-kneed).

What Causes a Bow-legged or Knock-kneed Deformity in Arthritis?

As arthritis progresses, the cartilage of the joint wears thin. The meniscus, or joint cushions, are also damaged and wear away. If the damage is more on one side of the joint than the other, as is usually the case, then the knee will take on a deformed appearance. When the inside, or medial side, of the joint is worn thin, a varus deformity (bow-legged) will result. When the outside, or lateral side, of the joint wears thin, a valgus deformity results (knock-knees).

What Is the Problem with This Type of Deformity?

When the knee is worn more on one side, the forces transmitted across the joint are altered. When the inside (medial side) wears thin, the force of your body weight becomes more centered on the worn out part of the joint. Therefore, the healthier part of the knee is spared the burden of your body weight, and the damaged portion gets the brunt of your weight.

This becomes a vicious cycle that leads to progression of arthritis.

How Does an Osteotomy of the Knee Help?

The idea of an osteotomy is to shift the weight-bearing forces to "unload" the worn out side of the joint, and place the forces on the healthier side of the joint.

Who Is an Ideal Candidate for a Knee Osteotomy Surgery?

The problem with knee osteotomies is that finding the right patient is very difficult.

Knee replacement surgery is very successful, and unless there is a good reason not to perform a replacement the total knee replacement is usually favored. Some patients, however, are not good candidates for knee replacement, especially patients who are young. Because knee replacements wear out over time, younger patients should be evaluated for alternative procedures.

The ideal patient for a knee osteotomy is a young, active person, who has arthritis limited to one side of the knee joint. The patient must have significant pain and disability such that surgery is warranted. The patient must understand that rehabilitation from this surgery is lengthy and difficult. Finally, osteotomies around the knee tend to last less than one decade. Then something more, usually a knee replacement, needs to be done. Some patients may find lasting relief with an osteotomy, but the majority of patients use a knee osteotomy surgery 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 involvement of only one side of the knee joint
  • The ability to cooperate with physical therapy and rehabilitation

Who Is Not a Good Candidate for a Knee Osteotomy?

Unfortunately, performing this surgery in the wrong patient can have poor outcomes. Therefore, you should discuss with your doctor the potential risks of this surgery. While many people want to avoid knee replacement surgery, the knee osteotomy is not right for everyone.

Patients generally should not consider this surgery if they have:

How is an osteotomy done?
An osteotomy uses is a procedure where the surgeon cuts the bone and then reorients the bone. There are two basic types of osteotomies: closing wedge, where a wedge of bone is removed to change the alignment of the bone; and, opening wedge, where bone is gapped open on one side to realign the bone. Depending on the type of deformity and the location of your osteotomy, your surgeon will choose one of these options.

Once the bone is cut and subsequently realigned, your surgeon may choose to use a metal plate and screws to hold the bones in the new position.

How long is the recovery from a knee osteotomy?
The recovery from a knee osteotomy can be difficult. Because the bone is cut, it needs time to heal. The total healing time is at least 8 weeks, and can take longer. Most patients need physical therapy to regain their 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 the surgery.

Orthopedic surgeons also face the problem of performing the surgery in a manner that will not make a subsequent knee replacement surgery more difficult. Finding a doctor experienced in this procedure is a good idea.

Other potential complications include problems with healing of the osteotomy (a nonunion), continued pain from arthritis, blood clots, and infection.

How successful is this surgery?
When done in the right patients, knee osteotomies are usually successful at decreasing pain caused by arthritis. They surgery tends to last about 8 to 10 years, and after that time, many patients will require total knee replacement. In a large group of patients, knee osteotomy gives good to excellent results in about:

  • 80% of patients for 5 years
  • 50% of patients for 10 years
  • 30% of patients for 20 years
Because of this, knee osteotomy is generally reserved for young, active patients, who want to delay the time until knee replacement.

References:
1. Naudie, D et al. "Survivorship of the high tibial valgus osteotomy" Clinical Orthopaedics and Related Research; 1999; 367:18-27.

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