Markolf K L, Burchfield D M, Shapiro M M, Cha C W, Finerman G A, Slauterbeck J L
Department of Orthopaedic Surgery, Biomechanics Research Section, University of California at Los Angeles, 90024-1795, USA.
J Bone Joint Surg Am. 1996 Nov;78(11):1728-34. doi: 10.2106/00004623-199611000-00014.
Seventeen fresh-frozen knee specimens from cadavera were instrumented with a load-cell attached to a mechanically isolated cylinder of subchondral bone containing the tibial insertion of the anterior cruciate ligament. The forces in the intact anterior cruciate ligament were recorded as the knee was passively extended from 90 degrees of flexion to 5 degrees of hyperextension without and with several constant tibial loads: 100 newtons of anterior tibial force, ten newton-meters of internal and external tibial torque, and ten newton-meters of varus and valgus moment. The anterior cruciate ligament was resected, and a bone-patellar ligament-bone graft was inserted. The knee was flexed to 30 degrees, and the graft was pre-tensioned to restore normal anterior-posterior laxity. The knee-loading experiments were repeated at this level of pre-tension (laxity-matched pre-tension) and at a level that was forty-five newtons greater than the laxity-matched pre-tension (over-tension). During passive extension of the knee, the forces in the graft were always greater than the corresponding forces in the intact anterior cruciate ligament. Over-tensioning of the graft increased the forces in the graft at all angles of flexion. At full extension, the mean force in the anterior cruciate ligament was fifty-six newtons; the mean force in the graft at laxity-matched pre-tension was 168 newtons, and it was 286 newtons in the over-tensioned graft. Greater pre-tensioning may be required when the knee demonstrates apparent tightening of the graft in flexion. The mean forces in the graft generated during all constant loading tests were greater than those for the intact anterior cruciate ligament over the range of flexion. When the graft was over-tensioned, the forces generated by the anterior tibial force and by varus and valgus moment increased but those generated by internal and external tibial torque did not. There was no significant change in the mean tibial rotation as a function of the angle of flexion of the knee after insertion of the graft; normal tibial rotation of the knee during passive extension (the so-called screw home mechanism) was eliminated.
对17个来自尸体的新鲜冷冻膝关节标本进行了检测，在包含前交叉韧带胫骨止点的软骨下骨机械隔离圆柱体上连接一个测力传感器。在膝关节被动从90度屈曲伸展至5度过伸时，分别在无以及施加几种恒定胫骨负荷的情况下记录完整前交叉韧带中的力，这些负荷包括：100牛顿的胫骨前向力、10牛顿·米的胫骨内外扭矩以及10牛顿·米的内翻和外翻力矩。切除前交叉韧带，插入骨-髌腱-骨移植物。将膝关节屈曲至30度，对移植物进行预张紧以恢复正常的前后松弛度。在这个预张紧水平（松弛度匹配预张紧）以及比松弛度匹配预张紧大45牛顿的水平（过度张紧）下重复膝关节加载实验。在膝关节被动伸展过程中，移植物中的力始终大于完整前交叉韧带中的相应力。移植物过度张紧会在所有屈曲角度下增加移植物中的力。在完全伸展时,前交叉韧带中的平均力为56牛顿；在松弛度匹配预张紧时移植物中的平均力为168牛顿，在过度张紧的移植物中为286牛顿。当膝关节在屈曲时移植物明显收紧时，可能需要更大的预张紧。在所有恒定负荷测试过程中，在屈曲范围内移植物产生的平均力大于完整前交叉韧带产生的平均力。当移植物过度张紧时，胫骨前向力以及内翻和外翻力矩产生的力增加，但胫骨内外扭矩产生的力没有增加。插入移植物后，平均胫骨旋转角度随膝关节屈曲角度没有显著变化；膝关节被动伸展过程中的正常胫骨旋转（即所谓的旋内机制）消失。
