Department of Orthopaedic Surgery, McGill University, Montreal, QC, Canada.
Knee Surg Sports Traumatol Arthrosc. 2011 Dec;19 Suppl 1:S77-85. doi: 10.1007/s00167-011-1527-8. Epub 2011 May 12.
Sixteen case reports of distal femur fractures as post-operative complications after anterior cruciate ligament (ACL) reconstruction have been described in the literature. The femoral tunnel has been suggested as a potential stress riser for fracture formation. Additionally, double bundle ACL reconstructions may compound this risk. This is the first biomechanical study to examine the significance of a stress riser effect of the femoral tunnel(s) after ACL reconstruction. The hypotheses tested in this study are that the femoral tunnel acts as a stress riser for fracture and that this effect increases with the size of the tunnel (8 mm vs. 10 mm) and with the number of tunnels (1 vs. 2).
Femoral tunnels simulating single bundle (SB) hamstring graft (8 mm), bone-patellar tendon-bone graft (10 mm), and double bundle (DB) ACL reconstruction (7, 6 mm) were drilled in fourth-generation saw bones. These three experimental groups and a control group consisting of native saw bones without tunnels were loaded to failure.
All fractures occurred through the tunnels in the DB group, whereas fractures did not consistently occur through the tunnels in the SB groups. The mean fracture load was 6,145N ± 471N in the native group, 5,691N ± 198N in the 8 mm SB group, 5,702N ± 282N in the 10 mm SB group, and 4,744N ± 418N in the DB group. The mean fracture load for the DB group was significantly lower when compared to the native, 8 mm SB, and 10 mm SB groups independently (P value = 0.0016, 0.0060, and 0.0038, respectively). The mean fracture loads for neither SB groups were not significantly different from the native group.
An anatomically placed femoral tunnel in single bundle ACL reconstruction in our experimental model was not a significant stress riser to fracture, whereas the two femoral tunnels in double bundle ACL reconstruction significantly decreased load to failure. The results support the sparsity of reported peri-ACL reconstruction femur fractures in single femoral tunnel techniques. However, the increased fracture risk in double bundle ACL reconstruction may be a cause for concern and impact patient selection.
已有文献报道了 16 例前交叉韧带（ACL）重建术后股骨远端骨折的病例报告。有人认为股骨隧道是导致骨折形成的潜在应力集中点。此外，双束 ACL 重建可能会增加这种风险。这是第一项研究股骨隧道（单隧道和双隧道）在 ACL 重建后是否具有应力集中效应的生物力学研究。本研究的假设是：股骨隧道是导致骨折的应力集中点，并且这种效应随着隧道的大小（8mm 与 10mm）和隧道数量（单隧道与双隧道）的增加而增加。
在第四代锯骨上模拟单束（SB）腘绳肌腱移植物（8mm）、骨-髌腱-骨移植物（10mm）和双束（DB）ACL 重建（7、6mm）的股骨隧道。将这三个实验组和一个不含有隧道的天然锯骨对照组进行失效负载测试。
所有骨折均发生在 DB 组的隧道中，而 SB 组的隧道中并未出现一致的骨折。天然组的平均骨折载荷为 6145N ± 471N，8mm SB 组为 5691N ± 198N，10mm SB 组为 5702N ± 282N，DB 组为 4744N ± 418N。与天然组、8mm SB 组和 10mm SB 组相比，DB 组的平均骨折载荷明显更低（P 值分别为 0.0016、0.0060 和 0.0038）。SB 组的平均骨折载荷与天然组无显著差异。
在我们的实验模型中，单束 ACL 重建的解剖学定位股骨隧道并不是导致骨折的显著应力集中点，而双束 ACL 重建的两个股骨隧道显著降低了失效负载。结果支持在单隧道技术中报告的 ACL 重建周围股骨骨折较少的观点。然而，双束 ACL 重建骨折风险的增加可能是一个令人担忧的问题，并会影响患者的选择。
