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The Ideal Patient for Unicompartmental Knee Implant

Doctors have found the ideal patient for a unicompartmental knee replacement (UKR). But first, what's a UKR? It's half of a knee replacement. In a UKR, usually only the inside (medial part) of the joint is replaced. It isn't always necessary to replace the entire joint when only one side is worn out or damaged. Unicompartmental implants work quite well for some patients with an uneven wear pattern.

Who are these patients? In other words, who is the ideal patient for a UKR? Someone over 65 years of age with a fairly quiet lifestyle. Doctors call this a lifestyle with low physical demands. The patients must have good knee motion and knee alignment.

What if you're not the right age, but you still need the operation? This is the focus of this study. This is only the third study to report the results of UKR in "younger" older adults (60 or younger). Patients were followed for an average of 11 years, so this is a long-term study. The study showed that height, weight, and body-mass index (BMI) didn't affect the results. The authors report a 93 percent success rate for UKR.

This means that this younger range of patients has more treatment options. In the past, a tibial osteotomy was the only real choice. Tibial osteotomy is the surgical removal of a wedge-shaped piece of bone from the lower leg bone (the tibia). The osteotomy is done where the tibia meets the knee. Taking out this piece changes the weight-bearing angle of the bone and joint. The goal is to change the force on the joint by shifting the pressure to the opposite side.

This study suggests that UKR may be useful for active middle-aged adults. It may eventually replace the need for tibial osteotomy procedures. These results are as good as with a total knee replacement.

References: Donald W. Pennington, DO, et al., Unicompartmental Knee Arthroplasty in Patients Sixty Years of Age or Younger. In Journal of Bone and Joints Surgery. October 2003. Vol. 85-A. No. 10. Pp. 1968-1973.

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