Features December, 2006 Issue

New Life For Old Knees

Replacing just part, rather than all, of a painful knee can reduce surgical complexity, recovery time and your hospital bill.

For the past 30 years, countless osteoarthritis patients have gained relief from persistent knee pain by having the entire joint replaced. After trying and failing with everything from prescription drugs and over-the-counter pain relievers to aquatic therapy and massage, you may conclude that total knee replacement is your only alternative as well. But thereís another option: unicompartmental knee arthroplasty, also known as partial knee replacement.

"Itís a less-invasive procedure than total knee replacement," says Wael Barsoum, M.D., an orthopaedic surgeon at Cleveland Clinic. "Itís quicker, it usually requires only a one-night stay in the hospital, and the rehab period is much shorter."

A total knee replacement involves the surgical removal and replacement with artificial parts of all three bony components of the joint the inner compartment, the outer compartment, and the kneecap. "It also requires the removal of at least one, and sometimes two, of the knee ligaments," says Dr. Barsoum.

Partial knee replacement involvesthe resurfacing of only one bone compartment and insertion of ametal/plastic implant. Ligaments are retained for joint flexibility.

"In partial knee replacement, we treat only one of the compartments. We resurface the ends of the bones and cap them with metal and plastic, which allows the compartment to function without cartilage. We donít have to remove the ligaments, so the joint functions more like a normal knee after the surgery."

Shorter rehab, less cost

A partial knee replacement takes approximately an hour. "Most patients stay in the hospital overnight and go home the next day," says Dr. Barsoum. "The majority will use a walker for the first week or so, then a cane for another week, and then nothing at all." By contrast, he notes, most patients who undergo total knee replacement will remain in the hospital for up to three days and may then go to an extended rehabilitation facility for up to two weeks. "It usually takes about six weeks for a patient who has undergone a partial replacement to walk normally," says Dr. Barsoum, "compared to approximately three months for patients who have had a total replacement."

Following the rehabilitation period, patients who have undergone either a partial or total knee replacement can, for example, swim, play tennis (doubles), and even ski. However, Dr. Barsoum notes, "Very high-demand sports, such as aggressively competitive singles tennis, are hard to do after any kind of knee arthroplasty."

On the downside, partial knee replacements do not relieve pain as effectively as total knee replacements. Nor do they last as long. A total knee replacement has an 80-90 percent chance of lasting for 20 years, whereas a partial replacement has an 80-90 percent chance of lasting for 10 to 12 years. In addition, partial knee replacements have a higher failure rate, in which case the patient would be considered for a total-knee procedure.

Best candidates

The ideal candidates for unicompartmental knee arthroplasty are patients in their 70s, for whom the partial procedure considering the normal human lifespan is likely to last the rest of their lives.

The ideal patient is also typically thin (no more than 20 percent over normal weight), at least moderately active, and has limited lower-limb deformity, such as severe knock-knees or bowlegs.

Poor candidates for partial knee replacement, says Dr. Barsoum, are "very heavy people" and those who hold high-demand jobs, such as factory workers and laborers, that may place excessive strain on the knees.

Although knee replacements, both total and partial, can effectively relieve arthritis pain, Dr. Barsoum advises patients to delay such knee procedures for as long as possible by taking advantage of proven and readily available approaches such as physical therapy, anti-inflammatory medications, and weight loss.