Abstract
Complete or partial disruption of the collateral ligament during total knee arthroplasty in severe deformities is a devastating complication which sometimes remains unnoticed at the time of surgery. We analysed 280 knees in 150 patients with over 30° varus with flexion (196 knees), flexion deformity alone (60 knees) & valgus deformity (24 knees) treated with primary total knee arthroplasty from January 2002 to January 2008. The mean age of patient was 65 years (ranging from 54 years to 78 years).
Problems encountered were avulsion of MCL from tibial attachment in 26 knees, femoral attachment avulsion with a bony fragment in 9 knees. Lateral collateral ligament was injured in 5 knees. In 12 knees with varus of >30° with element of tibial rotation medial release alone was not enough to balance the joint. Lateral collateral ligament tightening was needed in these cases using lateral epicondylar osteotomy. In 4 cases the medial collateral ligament was reconstructed using semi-tendinosus graft. Direct repair was not done in any case. Constrained knee prosthesis was used in only 22 knees to provide added stability. The mean duration of follow-up was 42 months. Stability of the knee was assessed clinically and on fluoro-radiography in full extension, 30°flexion and at 90° flexion of the knee. Seventy three percent (38/52) patients regained stability within 2 mm, 25% (13/52) had instability upto 4 mm and only one patient had gross instability needing hinge knee prosthesis. On the side of ligament reconstruction the ROM remained 10 to 15° less than the opposite side. Range of motion knee-brace was needed for 3 weeks in all cases. In cases with ligament reconstruction using Hamstring tendon, brace was used up to 12 weeks.
In conclusion identification of ligamentous insufficiency and its management will not only prevent unstable joint but also minimize the risk of revision in future. Lateral collateral ligament tightening is needed in certain select extreme varus deformities in addition to medial release.
