Anterior staple capsulorrhaphy for recurrent dislocation of the shoulder: a clinical and biomechanical study.

Thirty-three anterior staple capsulorrhaphies of the shoulder were reviewed at an average 49.7 months postoperatively (range 12 to 127 months); one postoperative dislocation occurred. The patients' quality of athletic participation improved with surgical therapy in 50%, remained the same in 38%, and was lowered in 12%. Average loss of external rotation was 11.4 degrees with the arm adducted and 13.9 degrees with the arm abducted 90 degrees. A positive apprehension sign persisted in 50%. Shoulder function was good or excellent in 84%. Mild pain was admitted by 55%, moderate pain by 6%, and severe pain by 3%. Staple malpositioning or loosening was identified in 12 shoulders; six of these patients had attributable clinical problems. Biomechanical studies in porcine bone were used to demonstrate that predrilling facilitates proper staple positioning without compromising staple fixation strength and, in a synthetic trabecular model, that a 5 degrees variance in the alignment of the staple holder during staple insertion weakens the fixation strength by 51% (P less than .001). The operation usually prevents recurrent dislocation, permits recovery of normal (or near normal) shoulder motion, and allows satisfactory return to competitive athletics. If staple malpositioning and loosening occur, they may cause clinical problems, including degenerative arthritis. Though most patients (92%) stated they would again have the operation, when practical, we recommend other methods of repair of capsule and labral detachment.