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Friday, March 17, 2000

Revision of components improves function

Soft tissue releases and revision of the components to correct malalignment improves function in patients who have had patellar dislocation after primary total knee replacement, according to co-author Kingsley R. Chin, MD, resident, Harvard Medical School, Boston. Dr. Chin presented his findings in poster exhibit 137.

"In the past, patient cases have been limited, resulting in only a small number of reports on these procedures," said Dr. Chin. "Risk factors for patella dislocation include intraoperative maltracking of the patella, malrotation of the femoral or tibial component, asymmetric patella preparation, increased composite patella thickness, and residual valgus alignment."

Forty-three patients (30 females and 13 males) were studied, and 33 patients presented with moderate to severe pain. Diagnoses included: osteoarthritis, 32; rheumatoid arthritis, 7; gout, 1; polio l; systemic lupus erythematosus, 1; and scleroderma, 1. The average age at revision was 68.5 years (range: 27 to 83 years). Multiple prosthetic designs were used for primary and revision surgeries. Treatment included: lateral release, 39; advancing the vastus medialis, 16; quadriceplasty, 11; tibial tubercle transfer, l, tendon transfer to reinforce the patella tendon, 1; and revision of the tibia and/or femoral components, 33. Patients were followed from 2 to 7 years (average: 4 years).

The average Knee Society Score for function and pain increased from 33.5 and 32.4 to 74.9 and 51.3 respectively. Average active extension lag decreased from 21 degrees to 8 degrees post-op. Eight patients had moderate to severe knee pain post-op. Knee flexion remained unchanged and there were no redislocations.

Co-authors of the study with Dr. Chin are: Richard D. Scott, MD, associate clinical professor, and Donald Bae, MD, resident, both from the Harvard Medical School.

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Last modified 28/February/2000 by IS