title: Rotator cuff repair with bioabsorbable screws: An in vivo and ex vivo investigation.
abstract: OBJECTIVE
  The purpose of this study was to evaluate in vivo the clinical outcomes of rotator cuff repairs with bioabsorbable screws compared with metal suture anchors, and to compare the ex vivo initial load to failure of rotator cuff repairs using 3 different bioabsorbable screws, suture anchors, and transosseous sutures.
  
  
  METHODS
  In vivo clinical outcomes investigation, and ex vivo biomechanical study.
  
  
  METHODS
  Three cohorts of patients with rotator cuff tears that measured less than 4 cm(2), were sequentially repaired with Mitek Rotator Cuff QuickAnchors (Mitek Surgical Products, Norwood, MA) (n = 9), Arthrex Headed Bio-Corkscrews (n = 9) (Arthrex, Naples, FL), and Mitek Rotator Cuff QuickAnchors (n = 9). Patients were systematically assessed with a specific shoulder questionnaire and 23 shoulder tests performed preoperatively and at 1 and 6 weeks, 3 and 6 months, and 1 year postoperatively. A correlative ex vivo biomechanical study was performed on 53 ovine shoulders to evaluate the initial failure load properties of bioabsorbable screws compared with fixation with suture anchors and transosseous sutures.
  
  
  RESULTS
  In the in vivo portion of the study, the cohort treated with the Headed Bio-Corkscrew demonstrated no improvement on any measured parameter until 1-year after rotator cuff repair. In contrast, shoulders repaired with Mitek Rotator Cuff QuickAnchors demonstrated improved overall shoulder function as early as 6 weeks postoperatively (P =.002), had a better constant score at 1-year after repair (88 +/- 9 v 73 +/- 17; P =.016), and a lower rate of revision rotator cuff repair (P =.029). In the ex vivo portion of the study, the bioabsorbable headed screws, Headed Bio-Corkscrew (100 +/- 30 N) and BioTwist (76 +/- 35 N), had inferior initial failure load properties compared with suture anchors (140 +/- 36 N) and transosseous sutures (147 +/- 68 N). In contrast, the BioCuff (190 +/- 56 N), a bioabsorbable implant that used a screw and serrated washer design, had equivalent initial failure load properties as the suture repairs.
  
  
  CONCLUSIONS
  This investigation had poorer early outcomes, a lower shoulder functional score 1-year after repair, and a higher rate of repeat surgery in patients who had their rotator cuff repaired with a bioabsorbable screw than in patients who had their shoulders repaired with a standard metal suture anchor. Furthermore, the biomechanical testing demonstrated a lower tensile load to failure in the tendons repaired with a simple screw design compared to suture anchors with a mattress stitch. Of note, the implant that used a screw and washer design demonstrated a greater ability to resist initial tensile load.
authors.affiliation: Orthopaedic Research Institute, Kogarah, Australia. craigacummins@hotmail.com
authors.forename: Craig A
authors.initials: CA
authors.lastname: Cummins
authors.forename: Sabrina
authors.initials: S
authors.lastname: Strickland
authors.forename: Richard C
authors.initials: RC
authors.lastname: Appleyard
authors.forename: Zoltan L
authors.initials: ZL
authors.lastname: Szomor
authors.forename: Jeanette
authors.initials: J
authors.lastname: Marshall
authors.forename: George A C
authors.initials: GA
authors.lastname: Murrell
mesh_terms: D020341:Absorbable Implants; D000368:Aged; D000818:Animals; D001182:Arthroscopy; D001863:Bone Screws; D015331:Cohort Studies; D003646:Debridement; D004868:Equipment Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020007:Implants, Experimental; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000453:epidemiology / Q000209:etiology; D011446:Prospective Studies; D020127:Recovery of Function; D012086:Reoperation / Q000706:statistics & numerical data; D017006:Rotator Cuff / Q000601:surgery*; D000070636:Rotator Cuff Injuries; D012756:Sheep; D020069:Shoulder Pain / Q000453:epidemiology / Q000209:etiology; D013045:Species Specificity; D013314:Stress, Mechanical; D013536:Suture Techniques / Q000295:instrumentation*; D016896:Treatment Outcome