A Biomechanical Study of Replacement of the Posterior Cruciate Ligament with a Graft. Part I: Isometry, Pre-Tension of the Graft, and Anterior-Posterior Laxity*

摘要: Twelve fresh-frozen knee specimens from cadavera were subjected to anterior-posterior laxity testing with 200 newtons of force applied the tibia; was performed before and after a femoral load-cell connected mechanically isolated cylindrical cap subchondral bone containing origin posterior cruciate ligament. The ligament then removed, proximal end thin trial isometer wire attached one four points designated on femur, displacement distal relative tibia measured over 120-degree range motion. potted ten-millimeter-wide bone-patellar ligament-bone graft centered load-cell. Isometry measurements repeated block free in tibial tunnel. Force recorded at (representing intra-articular portion graft) as pre-tension applied, use calibrated spring-scale, graft. A laxity-matched determined such that reconstructed 90 degrees flexion within millimeter installation Anterior-posterior insertion pre-tension. least amount change occurred when point femur (a margin ligament, midway between anterior borders ligament). greatest associated borders). mean displacements it center not significantly different corresponding this point. At flexion, by averaged 64 74 per cent (as load-cell) ranged six 100 (mean standard deviation, 43.0 ± 33.4 newtons). With numbers available, laxities different, any angle values CLINICAL RELEVANCE: Isometer readings provided an accurate indication length subsequently Anteriorly placed tunnels should be avoided, indicated increased tension, knee, region. always less than Therefore, tensioned avoid frictional losses severe bend passes plateau. correct pre-tensioning graft, normal 0 can restored. However, because considerable pre-tensions, we recommend greater forty-three for all patients ensure is