CLINICAL RELEVANCE OF THE TUNNEL POSITION AND THE POSITION OF THE INTERFERENCE SCREW AFTER ACL REPLACEMENT WITH A PATELLAR LIGAMENT TRANSPLANT

Fifty-eight patients had a prospective followup examination 1 year aft er arthroscopic ACL replacement. Stability measurement was done using a KT-1000 arthrometer. The side-to-side difference was less than 2 mm in 40 patients, 2-4 mm in 11 patients and more than 4 mm in 7 patients . The position of the tibial and femoral tunnels and interference scre w was measured from the postoperative X-ray. The positions of screws a nd tunnels were highly variable. However, there was no statistical cor relation between the position of the femoral interference screw and st ability measurement or between the position of the femoral interferenc e screw and flexion contracture or between the position of the tibial interference screw and the extension contracture. However, out of six patients with the femoral tunnel in an extremely anterior position (>2 0 mm anterior of the over the top position). only one patient had a st able joint (<2 mm difference in KT 1000 with 89 N anterior shear load) at follow-up. A screw divergence of more than 10 degrees was found in 18 patients. A tibial interference screw with more than 30 degrees of divergence was seen in seven patients. The primary fixation strength of the bone block could be diminished in these cases. This may have an impact on the early rehabilitation protocol.