Kocabey Y, Klein S, Nyland J, Caborn D
Department of Orthopaedic Surgery, Frazier Rehabilitation Institute, Suite 1003, University of Louisville, 210 East Gray Street, Louisville, KY 40202, USA.
Knee Surg Sports Traumatol Arthrosc. 2004 Mar;12(2):88-93. doi: 10.1007/s00167-003-0370-y. Epub 2003 Jul 4.
Tibial fixation remains the weak link of ACL reconstruction over the first 8-12 weeks postoperatively. This study compared the biomechanical properties of tibial fixation for a bone-patellar tendon-bone (BPTB) graft and a novel semitendinosus-bone composite (SBC) allograft with mixed cortical-cancellous bone dowels at each end. Seven paired, fresh frozen cadaveric knees (20-45 years) were stripped of all soft tissue attachments and randomly assigned to receive either the BPTB graft or SBC allograft. Grafts were placed into tibial tunnels via a standard protocol and secured with either a 10 mmx28 mm bioabsorbable (SBC) or titanium (BPTB) screw. Grafts were cycled ten times in a servo hydraulic device from 10-50 N prior to pull to failure testing at a rate of 20 mm/min with the force vector aligned with the tibial tunnel ("worst case scenario"). Wilcoxon Signed Rank Tests were used to evaluate biomechanical differences between graft types ( p<0.05). Tibial bone mineral density and interference screw insertion torque were statistically equivalent between graft types. The mode of failure for all constructs was direct screw and graft construct pullout from the tibial tunnel. Significant differences were not observed between graft types for maximum load at failure strength (BPTB=620.8+/-209 N vs. SBC=601.2+/-140 N, p=0.74) or stiffness (BPTB=69.8 N/mm+/-29 N/mm vs SBC=47.1+/-31.6 N/mm, p=0.24). The SBC allograft yielded significantly more displacement prior to failure than the BPTB graft (15.1+/-4.9 mm vs 9.2+/-1.3 mm, p=0.04). Increased construct displacement appeared to be due to fixation failure, with some evidence of graft tissue tearing around the sutures: Bioabsorbable screw (10 x 28 mm) fixation of the SBC allograft produced unacceptable displacement levels during testing. Further study is recommended using a titanium interference screw or a longer bioabsorbable screw for SBC graft fixation under cyclic loading conditions.
在术后最初的8 - 12周内，胫骨固定仍是前交叉韧带重建的薄弱环节。本研究比较了骨 - 髌腱 - 骨（BPTB）移植物和一种新型两端带有皮质 - 松质骨销的半腱肌 - 骨复合材料（SBC）同种异体移植物的胫骨固定生物力学特性。选取7对（20 - 45岁）新鲜冷冻尸体膝关节，去除所有软组织附着，随机分配接受BPTB移植物或SBC同种异体移植物。通过标准方案将移植物置入胫骨隧道，并用10 mm×28 mm的生物可吸收（SBC）或钛质（BPTB）螺钉固定。在伺服液压装置中，将移植物以10 - 50 N的力循环10次，然后以20 mm/min的速率进行拉伸至破坏测试，力矢量与胫骨隧道对齐（“最坏情况”）。采用Wilcoxon符号秩检验评估移植物类型之间的生物力学差异（p<0.05）。移植物类型之间的胫骨骨矿物质密度和干涉螺钉插入扭矩在统计学上相当。所有构建物的失效模式均为螺钉和移植物构建物直接从胫骨隧道拔出。在破坏强度下的最大载荷（BPTB = 620.8±209 N vs. SBC = 601.2±140 N，p = 0.74）或刚度（BPTB = 69.8 N/mm±29 N/mm vs SBC = 47.1±3l.6 N/mm，p = 0.24）方面，未观察到移植物类型之间存在显著差异。SBC同种异体移植物在破坏前产生的位移明显多于BPTB移植物（15.1±4.9 mm vs 9.2±1.3 mm，p = 0.04）。构建物位移增加似乎是由于固定失败，有一些证据表明移植物组织在缝线周围撕裂：在测试过程中，SBC同种异体移植物的生物可吸收螺钉（10×28 mm）固定产生了不可接受的位移水平。建议在循环加载条件下，对SBC移植物固定采用钛质干涉螺钉或更长的生物可吸收螺钉进行进一步研究。
