Study: All-suture anchor pullout results in decreased bone d
The hypothesis is that the all-suture anchor pull is less invasive and the cortical thickness affects the pull force. A study to assess the influence of the cortical and cancellous bone structure on all-suture and conventional anchor biomechanical properties was carried out and morphological bone damage after failure was compared.

30 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.

Results:
--The maximum pullout strength of all-suture anchors demonstrates a strong correlation to the adjacent cortical thickness 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; 141 mm3 vs. 212 mm3).

--The cortical defect is largest if the anchors are placed at a 45° angle.

Finally, the pullout power of all-suture anchors depends on the thickness of the humeral cortex, contrary to traditional anchors. In addition, stitching anchors shows a significant reduction in cortical defect and bone injury in the event of pull-outs. The practical implications of this study therefore are, because of their bone preservations, that all-suture anchors are favorable. Intra-operative decortication should also not be carried out and cortical thickness pre-operatively assessed to minimize the possibility of failure of anchor.

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