Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Institute of Biomechanics, TUHH Hamburg University of Technology, Hamburg, Germany.
Knee Surg Sports Traumatol Arthrosc. 2021 Jul;29(7):2212-2219. doi: 10.1007/s00167-020-06004-6. Epub 2020 Apr 24.
To evaluate the influence of cortical and cancellous bone structure on the biomechanical properties of all-suture and conventional anchors and compare the morphological bone damage after their failure. The hypothesis of the study is that all-suture anchor pullout is less invasive and that the pullout force is influenced by the cortical thickness.
Thirty human humeri were biomechanically tested as follows: starting with a load cycle from 20 to 50 N, a stepwise increase of the upper peak force by 0.05 N for each cycle at a rate of 1 Hz was performed. Analysis included maximum pullout strength for three different anchor implantation angles (45°, 90°, 110°) of the two anchor types. After anchor pullout, every sample underwent micro-CT analysis. Bone mineral density (BMD) and cortical thickness were determined at the anchor implantation site. Furthermore, the diameter of the cortical defect and the volume of the bone cavity were identified.
The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness (r = 0.82, p ≤ 0.05) with at least 0.4 mm needed to withstand 200 N. No correlation could be seen in conventional anchors. Moreover, no correlation could be detected for local BMD in both anchors. All-suture anchors show a significantly narrower cortical defect as well as a smaller bone cavity following pullout (4.3 ± 1.3 mm vs. 5.3 ± 0.9 mm, p = 0.037; 141 mm vs. 212 mm; p = 0.009). The cortical defect is largest if the anchors are placed at a 45° angle.
In contrast to conventional anchors, the pullout force of all-suture anchors depends on the thickness of the humeral cortex. Furthermore, all-suture anchors show a significantly smaller cortical defect as well as decreased bone damage in the case of pullout. Therefore, the clinical implication of this study is that all-suture anchors are advantageous due to their bone preserving ability. Also, intraoperative decortication should not be performed and cortical thickness should be preoperatively evaluated to decrease the risk of anchor failure.
评估皮质骨和松质骨结构对全缝线锚和传统锚的生物力学特性的影响，并比较它们失效后的形态学骨损伤。本研究的假设是全缝线锚钉的拔出损伤较小，且拔出力受皮质厚度的影响。
对 30 个人肱骨进行生物力学测试，具体如下：首先进行 20-50 N 的负荷循环，然后以 1 Hz 的速率逐步增加每个循环的上峰值力 0.05 N。分析包括两种锚钉类型在两种不同植入角度（45°、90°、110°）下的最大拔出强度。拔出锚钉后，对每个样本进行微 CT 分析。在锚钉植入部位测量骨矿物质密度（BMD）和皮质厚度。此外，确定皮质缺损的直径和骨腔的体积。
全缝线锚的最大拔出强度与相邻皮质厚度呈强相关（r=0.82，p≤0.05），至少需要 0.4mm 才能承受 200N 的力。传统锚钉则无相关性。此外，两种锚钉的局部 BMD 均无相关性。与传统锚钉相比，全缝线锚钉在拔出后皮质缺损更窄，骨腔更小（4.3±1.3mm 比 5.3±0.9mm，p=0.037；141mm 比 212mm，p=0.009）。如果将锚钉放置在 45°角，皮质缺损最大。
与传统锚钉相比，全缝线锚钉的拔出力取决于肱骨皮质的厚度。此外，全缝线锚钉在拔出时皮质缺损较小，骨损伤也较小。因此，本研究的临床意义是，全缝线锚钉具有保留骨的优势。此外，术中不应进行皮质骨切开术，应在术前评估皮质厚度，以降低锚钉失效的风险。
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