A novel suture anchor constructed of cortical bone for rotator cuff repair: a biomechanical study on sheep humerus specimens.

Abstract

The aim of this study was to evaluate biomechanical properties of a new type of suture anchors constructed of human cortical allograft bone and compare it with the similar standard titanium screw anchor for rotator cuff tears in sheep humerus model. Twenty-four paired sheep humeri were harvested from 12 male sheep aged 18months. Specimens were divided into cortical bone anchor group and titanium screw anchor group. The anchors loaded with two sutures were placed at the footprint of infraspinatus tendon. Cyclic loading test was performed from 10 to 60N at 1Hz for 500cycles and followed by a load-to-failure test at 33mm/sec. A paired t-test was used to compare the biomechanical properties of the anchors of each type. No anchors failed during the cyclic phase, and the cortical bone anchors were all pulled out intact. The cyclic displacement of the cortical bone anchor was not significantly greater than that of the titanium screw anchor (P > 0.05). Student's t test showed no statistically significant difference between anchors in terms of failure load (cortical bone anchor: 304.74 ± 64.46N versus titanium screw anchor: 328.45 ± 89.58N; P = 0.213), ultimate load (cortical bone anchor: 325.82 ± 76.45N versus titanium screw anchor: 345.61 ± 83.56N; P = 0.183), yield load (cortical bone anchor: 273.78 ± 44.75N versus titanium screw anchor: 284.72 ± 56.37N; P = 0.326) or stiffness (cortical bone anchor: 52.97 ± 14.28N/mm versus titanium screw anchor: 62.38 ± 18.35N/mm; P = 0.112). In vitro, this experimental study suggested no statistically significant difference in initial fixation stability between the new type anchor and titanium screw anchor at a chosen level of significance (P < 0.05). The new type of suture anchor constructed of cortical bone provides comparable initial fixation strength to a similar metallic anchor for rotator cuff repair.