Severe varus and valgus deformities treated by total knee arthroplasty.

We report a prospective case-controlled study which compared the outcome of knee replacement in seriously deformed and slightly deformed knees. There were 51 knees with varus or valgus deformity greater than 20 degrees matched for age, gender, disease, type of prosthesis and time of operation with a control group in which the alignment of the leg was within 5 degrees of normal. The clinical outcome at a mean 5.5 years was similar in the two groups. Some deformity persisted in 14 patients in the first group, 13 of whom were initially in valgus. These patients had a significantly poorer mean clinical outcome. Lateral dislocation or subluxation of the patella was found in four knees, all of which had had valgus deformity of 30 degrees or more.