Midwest Orthopaedics at Rush, Rush University Medical Center Chicago, IL, U.S.A..
Department of Orthopedic Surgery, University of Illinois at Chicago, Chicago, IL, U.S.A.
Arthroscopy. 2020 Nov;36(11):2875-2884. doi: 10.1016/j.arthro.2020.06.006. Epub 2020 Jun 15.
(1) To determine the area of posterior cruciate ligament (PCL) insertion sites on the lateral wall of the medial femoral condyle (LWMFC) that demonstrates the least amount of length change through full range of motion (ROM) and (2) to identify a range of flexion that would be favorable for graft tensioning for single-bundle (SB) and double-bundle (DB) PCL reconstruction.
Six fresh-frozen cadaveric knees were obtained. Three-dimensional computed tomography point-cloud models were obtained from 0° to 135°. A point grid was placed on the LWMFC and the tibial PCL facet. Intra-articular length was calculated for each point on the femur to the tibia at all flexion angles and grouped to represent areas for bone tunnels of SB and DB PCLR. Normalized length changes were evaluated.
Femoral tunnel location and angle of graft fixation were significant contributors to mean, minimum, and maximum normalized length of the PCL (all p < .001). Tibial tunnel location was not significant in any case (all p < .22). A femoral tunnel in the location of the posteromedial bundle of the PCL resulted in the least length change at all tibial positions (maximum change 13%). Fixation of the anterolateral bundle in extension or at 30° flexion resulted in significant overconstraint of the PCL graft. The femoral tunnel location for a SB PCLR resulted in significant laxity at lower ranges of flexion.
PCL length was significantly dependent on femoral tunnel position and angle of fixation, whereas tibial tunnel position did not significantly contribute to observed differences. All PCL grafts demonstrated anisometry, with the anterolateral bundle being more anisometric than the posteromedial bundle. For DB PCLR, the posteromedial bundle demonstrated the highest degree of isometry throughout ROM, although no area of the LWMFC was truly isometric. The anterolateral bundle should be fixed at 90° to avoid overconstraint, and SB PCLR demonstrated significant laxity at lower ranges of flexion.
Surgeons can apply the results of this investigation to surgical planning in PCLR to optimize isometry, which may ultimately reduce graft strain and the risk of graft failure. Additionally, DB PCLR demonstrated superiority compared with SB PCLR regarding graft isometry, as significant laxity was encountered at lower ranges of flexion in SB PCLRs. Fixation of the ALB at 90° flexion should be performed to avoid overconstraint in knee extension.
（1）确定在股骨内侧髁的外侧壁（LWMFC）上的后交叉韧带（PCL）插入点的区域，该区域在整个运动范围（ROM）中表现出最小的长度变化，（2）确定一个有利于单束（SB）和双束（DB）PCL 重建的移植物张紧的弯曲范围。
获得了 6 个新鲜冷冻的尸体膝关节。从 0°到 135°获得了三维计算机断层扫描点云模型。在 LWMFC 和胫骨 PCL 关节面上放置了一个点网格。在所有弯曲角度下，计算了股骨上每个点到胫骨的关节内长度，并将其分组以代表 SB 和 DB PCLR 的骨隧道区域。评估了归一化长度变化。
股骨隧道位置和移植物固定角度是 PCL 平均长度、最小长度和最大长度的重要决定因素（均<.001）。胫骨隧道位置在任何情况下均无显著意义（均<.22）。PCL 后内侧束位置的股骨隧道导致所有胫骨位置的长度变化最小（最大变化 13%）。前外侧束在伸展或 30°弯曲时固定会导致 PCL 移植物过度约束。SB PCLR 的股骨隧道位置导致较低弯曲范围的明显松弛。
PCL 长度主要取决于股骨隧道位置和固定角度，而胫骨隧道位置对观察到的差异没有显著贡献。所有 PCL 移植物均表现出各向异性，前外侧束比后内侧束的各向异性更大。对于 DB PCLR，尽管 LWMFC 没有真正的等距区，但在后内侧束在整个 ROM 中表现出最高的等距程度。为避免过度约束，应将前外侧束固定在 90°，并且 SB PCLR 在较低弯曲范围出现明显松弛。
外科医生可以将本研究的结果应用于 PCLR 的手术计划中，以优化等距性，这可能最终降低移植物的应变和移植物失效的风险。此外，与 SB PCLR 相比，DB PCLR 在移植物等距性方面具有优势，因为在 SB PCLR 中，较低弯曲范围会出现明显松弛。应在 90°弯曲时固定 ALB，以避免在膝关节伸展时过度约束。
