Summary
In 37 valgus deformed knees, the changes of the balance had been evaluated upto12 months. The balances of the TKA in valgus knee were adjusted spontaneously even in the case whose balance was not ideal during the surgery.
Abstract
INSTRUCTION
Keeping good medial and lateral soft tissue balance in valgus deformed knee is one of the most important factors for successful total knee arthroplasty (TKA). But this theory was based on the hypothesis that the value of the balances would not change after TKA. We evaluated the hypothesis.
Material And Method
Thirty seven knees ( 33 RA, 4 OA) of valgus deformity in 37 women were treated with TKA. Median valgus deformity was 15 degrees. Lateral laxity were measured by stress radiograph immediately after TKA (IM), 3months (3M) , 6 months (6M) , and 12 months after surgery (12M).
RESULT
Valgus laxity was 5.0 degree (IM), 4.8 degree (3M), 4.1 degree (6M), and 4.2 degree (12M). In the cases whose laxity was 3 degrees or less immediately after TKA, the values increased along the course 2.4, 2.9, 3.0, and 3.6 degrees. On the contrary, in the cases whose laxity was 7 degrees or more immediately after TKA, the values decreased along the time, as 8.2, 7.0, 4.7 and 4.7 degrees, respectively. Varus laxity was 5.5 degree, 4.1, 4.2 and 3.9 degrees, respectively. In the cases whose laxity was 3 degrees or less immediately after TKA, the values increased along the time 1.9, 2.8, 3.2 and 3.6 degrees, respectively. On the contrary, in the cases whose laxity was 7 degrees or more immediately after TKA, the values decreased along the time, as 9.3, 5.4, 5.0 and 3.8 degrees, respectively.
Discussion
Keeping ideal coronal balance in TKA is not always possible especially severely deformed knees. From this study it became clear that the coronal soft tissue balance could be adjusted automatically even in the case whose balance was not ideal during the surgery, if we achieved appropriate coronal alignment in TKA.