TOTAL KNEE ARTHROPLASTY FOR THE PATIENTS AFFECTING ANKYLOSING KNEE

Abstract

Between the year 1987 to 2005, 45 primary knee replacements were performed for 30 patients affecting ankylosing knee joint. 23 patients were having flexion fused deformities with 38 knee arthroplasty, ten of them were having flexion fused deformities over than 60 degrees. 18 cases were performed ipslateral THR & TKR. 2 AS patients undergone THR, TKR and total ankle replacement on the same anesthesia.

The other 7 patients were having extension ankylosing deformities with 9 primary TKR performed. All patients were post infection deformities with the exception of one Rheumatoid Arthritis and one hemophiliac patient with bilateral extension ankylosing deformities of the knee joint.

• Exposure of the knee joint and separation of the fused bones, providing a mobile joint space plays a crucial procedure for the next step of surgery for both flexion and extension ankylosing deformities. The following 2 points are important:

  1. First separate the fused bone between the femoral condyles and the patella, pay attention to the thickness of the patella button allowing sufficient bone stock with thickness and strength for patella replacement.

  2. Separate the fused bone between the femoral and tibial condyles allowing motion and space, pay attention that:

     1. the resection plane is 90 degrees perpendicular to the tibial axis and as proximal to the tibial plateau fused with the femoral condyles as possible.

     2. release and protect the blood supply and nerve of the posterior resection area avoiding damage to the nerve endings and the blood vessels.

• Soft tissue balancing is important, it is difficult to achieve the same flexion and extension gap. Usually the extension gap is narrow than flexion gap with flexion ankylosing deformities, on the contrary the flexion gap is narrow than extension gap with extension ankylosing deformities. Post operative rehabilitation and traction can gradually improve for the patients who less than 20 degrees flexion contracture deformities. For extension ankylosing deformities, post-operative rehabilitation can achieve better results even though the intra-operative ROM is less than 90 degrees but if the patient is stable in extension position.