Chao T T, Lew W D, Lewis J L, Lindquist C, Hong B, Arendt E
Navy General Hospital, Taiwan, Republic of China.
J Orthop Res. 1992 Nov;10(6):868-77. doi: 10.1002/jor.1100100616.
The objective of this study was to analyze the biomechanical effect of varying the level of prescribed load sharing between two segments of an anterior cruciate ligament (ACL) graft, and of separating the femoral attachments of these segments. Total anterior-posterior (AP) laxity was measured using an instrumented spatial linkage. Forces in graft segments were measured using buckle transducers. The two-segment graft was formed using the middle third of the patellar tendon with bone blocks and a synthetic augmentation device. Proximal fixation was obtained using a fixture which allowed changing the individual locations of the femoral attachments of the tendon and augmentation segments. Distal fixation was achieved using a force-setting device which allowed the loads in each segment to be set to prescribed levels. Total graft force, load sharing, and total AP laxity were recorded during the application of 100-N AP tibial loads at 0 degrees, 30 degrees, 60 degrees, 90 degrees, and 110 degrees flexion, for various combinations of load sharing set at extension and locations of femoral attachment sites. The load sharing, total graft force, and AP laxity during AP loading at the five test flexion angles were not significantly affected by changing the prescribed level of load sharing set at extension for a given femoral attachment configuration. However, varying the separate hole locations of the graft segments for a given level of load sharing significantly affected load sharing, total graft force, and AP laxity. If the tendon graft was located posteriorly (on the medial surface of the lateral femoral condyle) and the augmentation segment proximally, the augmentation carried a greater portion of the total force in flexion. If the augmentation segment was changed to a more posterosuperior location and the tendon posteroinferior, the tendon carried a higher percentage of the total force in flexion. AP laxity in most reconstruction states was significantly greater than in the normal joint with an intact ACL. The nature of the load sharing between the graft segments under AP tibial load over the flexion range can be controlled by the appropriate choice of the segments' femoral attachment locations.
本研究的目的是分析改变前交叉韧带（ACL）移植物两段之间规定的负荷分担水平以及分离这些段的股骨附着点的生物力学效应。使用仪器化的空间连杆测量前后（AP）总松弛度。使用带扣换能器测量移植物段中的力。两段移植物由带骨块的髌腱中间三分之一和一个合成增强装置形成。近端固定通过一个固定装置实现，该装置允许改变肌腱和增强段的股骨附着点的个体位置。远端固定通过一个力设定装置实现，该装置允许将每个段中的负荷设定到规定水平。在0度、30度、60度、90度和110度屈曲时施加100 N的AP胫骨负荷期间，记录总移植物力、负荷分担和总AP松弛度，这是针对伸展时设定的负荷分担和股骨附着点位置的各种组合。对于给定的股骨附着配置，改变伸展时设定的规定负荷分担水平，在五个测试屈曲角度的AP加载期间，负荷分担、总移植物力和AP松弛度没有受到显著影响。然而，对于给定的负荷分担水平，改变移植物段的单独孔位置会显著影响负荷分担、总移植物力和AP松弛度。如果肌腱移植物位于后方（在外侧股骨髁的内侧表面）且增强段位于近端，则增强段在屈曲时承担总力的更大比例。如果将增强段改变到更后上方的位置且肌腱位于后下方，则肌腱在屈曲时承担总力的更高百分比。大多数重建状态下的AP松弛度明显大于ACL完整的正常关节。在屈曲范围内AP胫骨负荷下，移植物段之间的负荷分担性质可以通过适当选择段的股骨附着位置来控制。
