[Total knee arthroplasty for extension ankylosing deformity].

OBJECTIVE

To discuss the outcomes and complications of total knee arthroplasty (TKA) for extension ankylosing deformity of the knee.

METHODS

From January 1996 to June 2006, total knee arthroplasty was performed on 8 patients (9 knees) with extension ankylosing deformity. The preoperative ROM of all patients was 0 degrees . Preoperative knee and function score of KSS were 44 points (from 10 to 68) and 17 points (from -10 to 55) respectively.

RESULTS

The complications of all TKAs included patellar tendon avulsion in 1 knee, partial fracture of inferior patella in 1 knee, hematoma in 1, superficial infection in 1. All patients were followed up for an average of 40.4 months (from 7.0 to 120.0). The average postoperative ROM was 89 degrees (from 50 degrees to 120 degrees ). Postoperative knee and function score of KSS were 81 points (from 55 to 93) and 79 points (from 50 to 90) respectively. Extension lag occurred in 2 knees, one was 10 degrees and the other was 25 degrees . One knee had undergone re-revision of changing the thicker tibial spacer for the reason of instability of joint 1 year after revision.

CONCLUSIONS

TKA performed in extension ankylosing deformity can get less satisfactory clinical results comparing with fixed flexion deformity. Exposure of the knee joint and separation of the fused bones, providing a mobile joint space plays crucial procedure for the next step of surgery. Preservation of sufficient bone stock of patella, protection of patellar tendon and blood supply of the knee and proper soft tissue balance are the key to TKA for extension ankylosing deformity.