title: Biomechanical comparison of bioabsorbable sutureless screw anchor versus suture anchor fixation for rotator cuff repair.
abstract: OBJECTIVE
  Anchors that directly fix the rotator cuff to bone without using sutures may simplify the challenges associated with arthroscopic rotator cuff repair. This study compared a bioabsorbable screw fixation device to a standard suture anchor fixation method.
  
  
  METHODS
  Randomized trial.
  
  
  METHODS
  A poly-L-lactide acid (PLLA), bioabsorbable screw anchor was compared with a metallic suture anchor loaded with No. 2 braided polyester suture in 12-week-old fresh-frozen bovine shoulders. Twelve specimens were randomly assigned to the 2 repair groups (6 per group). A 1 x 2-cm defect was created at the insertion site of the infraspinatus tendon. Two anchors were implanted 1 cm apart in the anatomic insertional area of the infraspinatus tendon. After preconditioning to 10 N, each construct was cycled between 10 and 180 N for up to a maximum of 2,500 cycles at a rate of 33 mm/second using a materials testing machine. The number of cycles to 5- and 10-mm gap formation at the repair site and mode of failure were recorded. Clinically, 10-mm gap formation defines complete fixation failure. Data were evaluated using an analysis of variance with significance set at P < .05.
  
  
  RESULTS
  Mattress suture fixation had significantly higher number of cycles to 10-mm failure compared with the PLLA device (P = .015). Failure occurred by tissue pullout in half the specimens and by device failure in the other half, without differences in failure modalities between groups.
  
  
  CONCLUSIONS
  This anchor provides low-profile fixation of the rotator cuff and eliminates suture placement and knot tying during arthroscopic and mini-open cuff repair. However, these data suggest that this anchor may not perform adequately under cyclic loading conditions in patients during postoperative rehabilitation.
  
  
  CONCLUSIONS
  This bioabsorbable anchor may not provide sufficient fixation for rotator cuff repair in humans.
authors.affiliation: Department of Orthopaedics, University of California San Diego, San Diego, California, USA.
authors.forename: Steve
authors.initials: S
authors.lastname: Lee
authors.forename: Andrew
authors.initials: A
authors.lastname: Mahar
authors.forename: Kelly
authors.initials: K
authors.lastname: Bynum
authors.forename: Robert
authors.initials: R
authors.lastname: Pedowitz
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws; D002417:Cattle; D004867:Equipment Design; D008422:Materials Testing; D019637:Orthopedic Procedures / Q000379:methods; D011100:Polyglycolic Acid; D011897:Random Allocation; D017006:Rotator Cuff / Q000503:physiopathology / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D013536:Suture Techniques
chemical_list: D011100:Polyglycolic Acid