The relationship of suture anchor failure and bone density to proximal humerus location: a cadaveric study

The purpose of this study was to evaluate spatial variations in the pullout strength of a suture anchor in the proximal humerus, and to correlate any differences with the local mineral density (BMD). Screw-type suture anchors threaded with wire sutures were inserted at six different anchor insertion sites in 11 human cadaveric humeri (average age, 80 years). Load to failure tests with forces applied in line with the axis of insertion were performed, and bone mineral density measurements were then made at these sites. The greater tuberosity showed anterior and posterior differences in anchor pullout force (P = .03), with the posterior portion showing higher strength (154 N) than the anterior area (96 N). Neither the lesser tuberosity (185 N anterior area and 177 N posterior area) nor the humeral neck (170 N anterior and 174 N posterior area) showed significant differences, and they were statistically equivalent to the greater tuberosity. There was no demonstrable difference in BMD at any of the six sites tested. There is no support for the hypothesis that significant differences in load to failure exist among the lesser tuberosity, humeral neck, and greater tuberosity. Also, there is no support for the hypothesis that the load to failure variations for the proximal humerus are dependent on BMD. Bone mineral density appears to have no correlation with the pullout strength of a screw-type suture anchor.