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Knee Replacement

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Picture #1 is the original "unispacer" designed by Dr. Duncan McKeever of Houston, Texas. Dr. McKeever abandoned this design as the results of total knee replacement were superior.

Picture #2 is the "modern unispacer" produced by the Sulzer Corporation recently with results no better than those of Dr. McKeever. "Those who cannot remember history are condemned to repeat it" - George Santayana (1863-1952).

Knee replacement may be total or partial. As discussed before, sometimes only the patellofemoral joint is replaced. In some instances, either the inside half or the outside half of the knee is replaced. In Houston in the 1960s, Dr. Duncan McKeever developed a type of replacement in which half of the knee was replaced. This was a metal wedge that was placed into the worn side of the joint.

This device was helpful for patients, but as total knee replacements improved and those results in patient satisfaction with total knee proved to be superior to the partial knee replacement, this knee replacement fell out of favor. In the early 2000s, the Sulzer Corporation released and aggressively marketed a device known as the "unispacer" (see image at right) which was based off of Dr. McKeever's and other designs of the '60s.

Unfortunately, because Dr. McKeever had FDA approval for his device, and because the FDA allows for new products which are similar to old products be introduced without further FDA testing, this unispacer was released to the market without additional clinical studies. Subsequently, clinical studies using this device have shown that its use is ill-advised. Although there are rare reports of success, infections and other failures have led most joint replacement specialists (Dr. Clyburn included) to recommend against this procedure.

	This set of pictures are of a truly modern unicompartmental knee replacement patient. The first is an x-ray showing loss of joint space on the inside (medial) joint space. The second is an intra-operative picture of the unicompartmental knee replacement in the knee. The third is an x-ray of the unicompartmental knee replacement in the knee.