874 Pull-out strength of suture anchors for rotator cuff and Bankart lesion repairs AARON T. HECKER, MS, MARIE SHEA, MS, JOHN O. HAYHURST, MD, ELIZABETH R. MYERS, PhD, LOUIS W. MEEKS, MD, AND WILSON C. HAYES,* PhD From the Orthopaedic Biomechanics Laboratory, Department of Orthopaedic Surgery, Charles A. Dana Research Institute, Beth Israel Hospital and Harvard Medical School, Boston, Massachusetts ABSTRACT Surgical reconstructions of anterior-inferior shoulder instabilities and rotator cuff injuries require secure fix- ation of soft tissue to bone. Sutures are inserted directly through transosseous tunnels in current techniques, which are surgically complex and not always adequate for fixation strength. Using fresh-frozen cadaveric hu- man specimens, our objectives were 1) to compare immediate pull-out strength of two versions of polyace- tal suture anchors (wedge and rod) with conventional suture-only attachment techniques in Bankart lesion and rotator cuff repairs, and 2) to compare pull-out strength of the two polyacetal suture anchors with a metallic suture anchor. Our results indicate no signifi- cant differences in fixation strength of Bankart lesions or rotator cuff repairs using sutures only, or using wedge or rod polyacetal suture anchors (P = 0.70). Pull-out force did not differ significantly (P = 0.37) between the two polyacetal anchors. Polyacetal an- chors exhibited higher pull-out forces than metallic an- chors when inserted into metaphyseal regions of the tibia and significantly higher pull-out forces (P < 0.001) when inserted into metaphyseal regions with thicker cortical walls. Our results indicate that both polyacetal suture anchors provide adequate immediate fixation for soft tissue repairs in the human shoulder. The shoulder is dislocated more frequently than any other human joint, causing limitation of motion and pain in ath- letes and nonathletes of all ages.8,14 Bankart lesions’ and rotator cuff tears, two of the major injuries associated with dislocations, often require surgical repair.5,6,10,14,20 These injuries involve tears at the sites of tendon, articular capsule, and ligament attachment to bone. Surgical reconstruction requires secure soft tissue fixation to bone; techniques that employ staples, screws and washers, or sutures have been proposed. However, the staples used for repairing rotator cuff tears often prove inadequate in the thin cortical bone of the humeral head and may be easily dislodged by gleno- humeral motion.14,22 The classic Bankart procedure,’ a widely accepted method of treating anterior-inferior gleno- humeral instability, uses sutures that are inserted directly through transosseous tunnels. Although the surgical expo- sure involves minimal trauma and skin incision&dquo; and leads to excellent clinical results with reported recurrence rates of 3.5% to 4%, 7,19 the procedure of reattaching the torn liga- ment or tendon can be time-consuming and difficult.’ While modifications that decrease the operating time for standard rotator cuff&dquo;,&dquo; and Bankart lesion4,12,17 repairs are available, these approaches also are technically demanding. The strength of various repair techniques has been ex- amined by many investigators. France et a1.8 compared the initial strength and the mode of failure of simulated rotator cuff repairs in cadaveric specimens. They used standard sutures, reinforced sutures such as expanded polytetraflu- oroethylene (PTFE) (W. L. Gore & Associates, Flagstaff, AZ) and polydioxanone bands (Ethicon PDS, Ethicon Inc., Somerville, NJ), and two stapling methods. The sutures reinforced with a PTFE patch were significantly stronger than the nonaugmented repairs. While there were no statis- tically significant differences in strength between the non- arthroscopic staple repairs and nonaugmented or patch- augmented suture repairs, the use of staples was discouraged because of their tendency to migrate into the joint, which results in cartilage damage and arthritis, and their tendency to cut through the bone and tendon. Paulos et al.16 conducted in vivo studies on primates to determine the biomechanical and histologic effects of a synthetic soft tissue patch and a high molecular weight hyaluronic acid on the success of a . Address correspondence and reprint requests to: Wilson C. Hayes, PhD, Orthopaedic Biomechanics Laboratory, Beth Israel Hospital, 330 Brookline Avenue, Boston, MA 02215.