Boniello Michael R, Schwingler Paul M, Bonner Justin M, Robinson Samuel P, Cotter Andrew, Bonner Kevin F
Eastern Virginia Medical School, Norfolk, Virginia, U.S.A.
Jordan-Young Institute for Orthopedic Surgery & Sports Medicine, Virginia Beach, Virginia, U.S.A.
Arthroscopy. 2015 Jun;31(6):1084-90. doi: 10.1016/j.arthro.2014.12.023. Epub 2015 Feb 19.
The purpose of this study was to compare the tensile strength of hamstring grafts of varying combined pull-through diameters within the clinically relevant range of 6 to 9 mm.
We tested 44 non-irradiated allograft hamstring grafts (11 per group). Combined looped semitendinosus and gracilis grafts were allocated to the 6-, 7-, 8-, or 9-mm group based on the smallest-diameter lumen that the graft could be "pulled through" using a surgical sizing instrument. Testing was performed on an Instron materials testing machine (Instron, Norwood, MA). Samples were secured with cryoclamps, prestressed, and pulled to failure at a rate of 10% gauge length per second.
The mean load to failure was 2,359 ± 474 N, 3,263 ± 677 N, 3,908 ± 556 N, and 4,360 ± 606 N for the 6-, 7-, 8-, and 9-mm grafts, respectively. Minimum failure loads were as low as 1,567 N, 2,288 N, 2,874 N, and 3,720 N for each group, respectively. There were statistically significant differences between the 6- and 7-mm, 6- and 8-mm, 6- and 9-mm, and 7- and 9-mm groups (P = .01).
Statistically different increasing tensile strength was seen as graft diameter increased. Significant variability exists in the strength of multi-stranded hamstring allografts within the diameter range of 6 to 9 mm that often falls well below the commonly accepted value of 4,000 N for a hamstring graft.
Recent evidence suggests a higher early failure rate of hamstring autografts in subsets of patients with graft diameters of 8 mm or less. This study may increase awareness that hamstring grafts may not be nearly as strong as previously appreciated and that increasing tendon diameters by 1 to 2 mm may dramatically affect graft strength. These data may be helpful in preoperative discussions regarding variable hamstring size, strength, and potential intraoperative augmentation options.
本研究的目的是比较在6至9毫米这一临床相关范围内不同组合穿通直径的绳肌移植物的拉伸强度。
我们测试了44条未辐照的同种异体绳肌移植物（每组11条）。根据使用手术尺寸测量仪器时移植物能够“穿通”的最小内径，将半腱肌和股薄肌的联合环行移植物分配到6毫米、7毫米、8毫米或9毫米组。测试在英斯特朗材料试验机（英斯特朗公司，马萨诸塞州诺伍德）上进行。样本用低温夹固定，施加预应力，并以每秒10%标距长度的速率拉伸至破坏。
6毫米、7毫米、8毫米和9毫米移植物的平均破坏载荷分别为2359±474牛、3263±677牛、3908±556牛和4360±606牛。每组的最小破坏载荷分别低至1567牛、2288牛、2874牛和3720牛。6毫米与7毫米、6毫米与8毫米、6毫米与9毫米以及7毫米与9毫米组之间存在统计学显著差异（P = 0.01）。
随着移植物直径增加，观察到拉伸强度在统计学上呈不同程度增加。在6至9毫米直径范围内的多股绳肌同种异体移植物强度存在显著变异性，其强度通常远低于绳肌移植物普遍接受的4000牛的值。
最近的证据表明，在移植物直径为8毫米或更小的部分患者中，自体绳肌移植物的早期失败率较高。本研究可能会提高人们的认识，即绳肌移植物可能不像以前认为的那么强壮，并且将肌腱直径增加1至2毫米可能会显著影响移植物强度。这些数据可能有助于在术前讨论绳肌大小、强度的变化以及潜在的术中增强选择。
