Missouri Orthopaedic Institute, Thompson Laboratory for Regenerative Orthopaedics, University of Missouri, Columbia, Missouri, USA.
Sports Medicine and Shoulder Service, Tissue Engineering, Regeneration, and Repair Program, Hospital for Special Surgery, New York, New York, USA.
Am J Sports Med. 2018 Mar;46(4):915-923. doi: 10.1177/0363546517745624. Epub 2018 Jan 3.
Anterior cruciate ligament (ACL) grafts that are placed for reconstruction are subject to complex forces. Current "anatomic" ACL reconstruction techniques may result in greater in situ graft forces. The biological effect of changing magnitudes of ACL graft force on graft-tunnel osseointegration is not well understood.
The research objective is to determine how mechanical force on the ACL graft during knee motion affects tendon healing in the tunnel.
Controlled laboratory study.
Male rats (N = 120) underwent unilateral ACL reconstruction with a soft tissue flexor tendon autograft. ACL graft force was modulated by different femoral tunnel positions at the time of surgery to create different graft force patterns with knee motion. External fixators were used to eliminate graft load during cage activity. A custom knee flexion device was used to deliver graft load through controlled daily knee motion. Graft-tunnel healing was then assessed via biomechanical, micro-computed tomography, and histological analyses.
ACL graft-tunnel healing was sensitive to dynamic changes in graft forces with postoperative knee motion. High ACL graft force with joint motion resulted in early inferior ACL graft load to failure as compared with knees that had low-force ACL grafts and joint motion and knees that were immobilized (mean ± SD: 5.50 ± 2.30 N vs 9.91 ± 3.54 N [ P = .013] and 10.90 ± 2.8 N [ P = .001], respectively). Greater femoral bone volume fraction was seen in immobilized knees and knees with low-force ACL grafts when compared with high-force ACL grafts at 3 and 6 weeks.
The authors were able to demonstrate that ACL graft-tunnel incorporation is sensitive to dynamic changes in ACL graft force with joint motion. Early high forces on the ACL graft appear to impair graft-tunnel osseointegration.
Current "anatomic" techniques of ACL reconstruction may result in greater graft excursion and force with knee motion. Our results suggest that the postoperative rehabilitation regimen may need to be modified during the early phase of healing to protect the reconstruction.
用于重建的前交叉韧带（ACL）移植物会受到复杂的力的作用。目前的“解剖”ACL 重建技术可能会导致移植物在原位产生更大的力。改变 ACL 移植物力的大小对移植物-隧道骨整合的生物学影响还不是很清楚。
本研究的目的是确定膝关节运动过程中 ACL 移植物上的机械力如何影响隧道内的肌腱愈合。
对照实验室研究。
雄性大鼠（N=120）行单侧 ACL 重建，使用软组织屈肌腱自体移植物。在手术时通过改变股骨隧道位置来调节 ACL 移植物力，以在膝关节运动时产生不同的移植物力模式。使用外固定器在笼活动期间消除移植物负荷。使用定制的膝关节弯曲装置通过受控的每日膝关节运动来传递移植物负荷。然后通过生物力学、微计算机断层扫描和组织学分析评估移植物-隧道愈合情况。
ACL 移植物-隧道愈合对术后膝关节运动中移植物力的动态变化很敏感。与关节运动中具有低力 ACL 移植物和关节运动以及固定膝关节的膝关节相比，高 ACL 移植物力导致早期 ACL 移植物失效的负荷较低（平均±标准差：5.50±2.30N 比 9.91±3.54N[P=0.013]和 10.90±2.8N[P=0.001]）。与高 ACL 移植物相比，在 3 周和 6 周时，固定膝关节和低 ACL 移植物的股骨骨体积分数更大。
作者能够证明 ACL 移植物-隧道结合对关节运动中 ACL 移植物力的动态变化很敏感。ACL 移植物上的早期高力似乎会损害移植物-隧道骨整合。
目前 ACL 重建的“解剖”技术可能会导致膝关节运动时移植物的伸展和力更大。我们的结果表明，在愈合的早期阶段，术后康复方案可能需要进行修改，以保护重建。
