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Unicondylar Knee Replacement

Dr.A.K.Venkatachalam, MS, DNB, FRCS, MCH Orth

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Partial or unicondylar knee replacement is an effective surgical procedure to cure partial knee osteoarthritis in middle aged patients in India.

Many middle-aged men and women develop osteoarthritis of the knee. In Indians and Caucasians, Osteoarthritis of the knee affects the inner half or medial compartment to start with and then proceeds to affect the outer half or lateral compartment. The erect posture of man and a few other animals contributes to 60 percent of weight transmission through the inner side of the joint which contributes to wear. Localized attrition occurs in the beginning as a so called "lesion." Later it gradually affects the front and inner portion of the inner half of the lower end of the thigh and leg bones (antero medial wear). This is obvious on standing x rays as a pit or depression. Clinically these individuals may be bow legged since childhood.

The standard permanent orthopedic surgical treatment for osteoarthritis knee has been a total knee replacement. However the ideal candidate for a TKR is a person beyond 65 years, when he can live out the life of an artificial joint which is about 15 years. Clearly someone in their fifties is not suited for a TKR as his/her life span would exceed that of the joint and he would need a revision knee replacement later on. Surgical alternatives include an osteotomy and a Uni condylar knee replacement. In an osteotomy, the thigh or leg bone is divided and re aligned so that the abnormal weight bearing axis is normalized. Pain relief is provided for a period of up to 10 years but is not total. It is suited for manual laborers whose work demands would wear out an artificial joint.

A unicondylar knee replacement substitutes the inner worn half of the joint with prosthesis. The bony resection is restricted to the affected half alone sparing the outer half and the patella unlike a total knee replacement. The operation can be done by a minimally invasive technique sparing the quadriceps muscle. The pre requisites are that the inner half alone must be worn as seen on x- rays and the anterior cruciate ligament should be intact. The technique of insertion is demanding but the rewards to the patient are numerous. Shorter hospital stay, quicker recovery, small incisions, no blood transfusion, less pain, less cost (vs. TKR) and better function (squatting, kneeling, climbing stairs) are the much acclaimed benefits. The knee feels more natural as sensations carried by the ligaments are intact.

The Oxford unicompartmental knee is a representative type and is a mobile bearing uni knee. Survivorship analysis is 98 percent at 15 years. The wear of the mobile polyethylene insert is minimal.

In the US uni compartmental knee replacements are making a come back on patient demand in this decade after a revival in the 1990’s. In India, the procedure is available in Chennai.

Visit www.kneeindia.com for further information on knee disorders.


Consultant Orthopedic surgeon,Chennai

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