20° Anchor Insertion Technique Toward the Subchondral Bone in Rotator Cuff Repairs for Patients With Osteoporosis Compared With the Traditional 45° Deadman Angle

Background: Rotator cuff repair in patients with osteoporosis is challenging due to compromised bone anchor stability. While the traditional 45° Deadman angle is biomechanically favored in normal bone, its efficacy in osteoporosis remains uncertain, potentially contributing to complications such as anchor-related cysts and retears. This study compared the clinical outcomes and complication rates between a traditional 45° angle and a shallower 20° angle directed toward the denser subchondral bone in patients with osteoporosis undergoing double-row rotator cuff repair. Purpose: To compare the clinical outcomes of rotator cuff repair in patients with osteoporosis using the traditional 45° Deadman angle versus the insertion angle of approximately 20° directed toward the subchondral bone. Study Design: Cohort study; Level of evidence, 3. Methods: A retrospective analysis was conducted on patients diagnosed with rotator cuff tears and osteoporosis who underwent double-row suture anchor repair from January 2018 to January 2022. Patients were divided into 2 groups based on the angle of the medial row anchors, measured coronally, during intraoperative implantation and on postoperative magnetic resonance imaging (MRI). Group 1 (n = 62) had the medial row anchors inserted at an angle of approximately 45° (the Deadman angle) in the coronal direction, while group 2 (n = 65) had the inner row anchors inserted at an angle of approximately 20° in the coronal direction. A comparison of the general data between the 2 groups is presented. After a minimum follow-up of 2 years, postoperative clinical outcomes were compared with the American Shoulder and Elbow Surgeons (ASES), University of California, Los Angeles (UCLA), Constant Score (CS), and visual analog scale (VAS) scores, as well as the shoulder range of motion (ROM). Perianchor cyst and retear were evaluated through MRI. Results: Significant improvements were observed in all clinical outcomes for both groups, from baseline preoperative evaluations to the final follow-up assessments ( P = .001 for ASES score, UCLA score, CS, VAS score, and ROM), with no significant differences between the 2 groups ( P > .05). However, at the final follow-up, group 2 demonstrated significantly lower perianchor cyst grading and a significantly lower retear rate (13.84% vs 37.09%) compared with group 1 ( P < .05). Conclusion: Both anchor insertion techniques resulted in acceptable shoulder clinical outcomes for patients with osteoporosis undergoing rotator cuff repair. However, the 20° insertion angle toward the subchondral bone was associated with a significantly lower incidence of perianchor cysts and retears than the traditional 45° Deadman angle.