The Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, SW7 2AZ, UK.
Basingstoke and North Hampshire Hospital, Basingstoke, UK.
Knee Surg Sports Traumatol Arthrosc. 2018 Aug;26(8):2430-2437. doi: 10.1007/s00167-018-4932-4. Epub 2018 Apr 5.
A common problem during ACL reconstruction is asymmetry of proximal-distal graft diameter leading to tunnel upsizing and graft-tunnel mismatch. Compression downsizing provides a graft of uniform size, allowing easy passage into a smaller tunnel. The purpose of this study was to quantify the graft compression technique and its effects on graft biomechanics and stability. It was hypothesised that compression downsizing would significantly reduce cross-sectional area (CSA); that no significant changes in graft biomechanics would occur; graft fixation stability would be improved.
Sixty-eight non-irradiated peroneus longus (PL) tendons were investigated. Twenty were halved and paired into ten four-strand grafts, 20 strands were compressed by 0.5-1 mm diameter and changes in CSA recorded using an alginate mould technique. The following properties were compared with 20 control strands: cyclic strain when loaded 70-220 N for 1000 cycles; stiffness; ultimate tensile load and stress; Young's modulus. 24 PL tendons were quadrupled into grafts, 12 were compressed and all 24 were submerged in Ringer's solution at 37 °C and the CSA recorded over 12 h. Twelve compressed and 12 control quadrupled grafts were mounted in porcine femurs, placed in Ringer's solution for 12 h at 37 °C and graft displacement at the bone tunnel aperture recorded under cyclic loading.
Mean decreases in CSA of 31% under a stress of 471 kPa and 21% under a stress of 447 kPa were observed for doubled and quadrupled grafts, respectively. Compressed grafts re-expanded by 19% over 12 h compared to 2% for controls. No significant differences were observed between compressed and control grafts in the biomechanical properties and graft stability; mean cyclic displacements were 0.3 mm for both groups.
No detrimental biomechanical effects of graft compression on allograft PL tendons were observed. Following compression, the grafts significantly increased in size during in vitro joint simulation. No significant difference was observed in graft stability between groups. Graft compression did not cause adverse mechanical effects in vitro. Smaller tunnels for compressed grafts reduce bone loss and ease anatomical placement.
ACL 重建过程中的一个常见问题是移植物近端-远端直径的不对称，导致隧道扩大和移植物-隧道不匹配。压缩缩径可提供均匀直径的移植物，便于进入较小的隧道。本研究的目的是量化移植物压缩技术及其对移植物生物力学和稳定性的影响。假设压缩缩径会显著减小横截面积（CSA）；移植物生物力学不会发生显著变化；移植物固定稳定性会得到改善。
研究了 68 根未经辐照的腓骨长肌（PL）肌腱。20 根肌腱被对半切开并配对成 10 根四股移植物，20 根肌腱用 0.5-1mm 直径的压缩，并用藻酸盐模具技术记录 CSA 的变化。与 20 根对照肌腱相比，比较了以下特性：在 70-220N 下循环加载 1000 次时的循环应变；刚度；极限拉伸载荷和应力；杨氏模量。24 根 PL 肌腱被四股化，12 根被压缩，所有 24 根肌腱都被浸泡在 37°C 的林格氏溶液中，并在 12 小时内记录 CSA。12 根压缩和 12 根对照四股化的移植物被安装在猪股骨中，在 37°C 的林格氏溶液中放置 12 小时，并在循环加载下记录骨隧道开口处的移植物位移。
在 471kPa 的应力下，双股和四股移植物的 CSA 平均分别减少了 31%和 21%。与对照组的 2%相比，压缩后的移植物在 12 小时内重新扩张了 19%。在生物力学特性和移植物稳定性方面，压缩和对照移植物之间没有观察到显著差异；两组的平均循环位移均为 0.3mm。
对同种异体 PL 肌腱进行移植物压缩没有观察到不利的生物力学影响。在体外关节模拟后，移植物的尺寸显著增大。两组之间的移植物稳定性没有差异。移植物压缩在体外没有造成不良的力学影响。对于压缩后的移植物，较小的隧道可以减少骨质丢失并便于解剖放置。
