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Choosing a Joint Implant when Converting a Fused Knee

When a knee joint has been fused in place, doctors can sometimes convert the fusion and restore the hinge motion at the knee by implanting a new knee joint. The authors of this study review 36 cases of fused-knee conversion. Most of the patients were young (ranging from 23 to 58) and had a fused knee for many years.

The study took place in Korea, where childhood tuberculous arthritis is more common. More than half the patients studied were in this category. The rest had infectious arthritis. Some knees had fused naturally, while others were fused surgically.

The joint replacement used in this group of patients was different from the implant normally recommended. A constrained total knee is advised when collateral ligaments along the sides of the knee are absent or weak. However, doctors at the Joint Replacement Center of Korea used a nonconstrained, posterior stabilized total knee replacement.

Results were good. Sixty-one percent of all patients were free from pain, and the rest noted only mild pain after a long walk. The knees were stable, and all patients were pleased with the result. They all said they would do it again if given the choice.

There were some problems with muscle weakness and skin infections. The authors think that even with these problems, total knee replacement in fused knees is a good idea. More than one kind of joint implant can be used.

References: Young-Hoo Kim, MD, et al. Conversion of a Fused Knee with Use of a Posterior Stabilized Total Knee Prosthesis. In The Journal of Bone and Joint Surgery. June 2003. Vol. 85-A. No. 6. Pp. 1047-1050.

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