title: Effect of pretension and suture needle type on mechanical properties of acellular human dermis patches for rotator cuff repair.
abstract: BACKGROUND
  Dermal grafts are used for rotator cuff repair and augmentation. Although the in vitro biomechanical properties of dermal grafts have been reported previously, clinical questions related to their biomechanical performance as a surgical construct and the effect of surgical variables that could potentially improve repair outcomes have not been studied.
  
  
  METHODS
  This study evaluated the failure and fatigue biomechanics of acellular dermis constructs tested in a clinically relevant size (4 × 4 cm patches) and manner (loaded via sutures) for rotator cuff repair. Also investigated were the effect of 2 surgical variables: (1) the fixation of grafts under varying magnitudes of pretension (0, 10, 20N), and (2) the use of reverse-cutting vs tapered needles for suturing grafts.
  
  
  RESULTS
  Dermis constructs stretched ∼25% before bearing significant loads in the high stiffness region. Although 91% of the patches withstood 2500 cycles of loading to 150 N, the constructs stretched 13 to 19 mm after fatigue loading. This elongation could be reduced by 20% to 32% when reverse-cutting needles were used to prepare constructs or by applying 20 N of in situ circumferential pretension to the constructs before loading.
  
  
  CONCLUSIONS
  Although dermis patches demonstrated robustness for use in rotator cuff repair, the patches underwent significant, substantial, and presumably nonrecoverable elongation, even at low physiologic loads. This study indicates that use of reverse-cutting needles for suture passage, preconditioning (cyclically stretching several times), and/or surgical fixation under at least 20 N of circumferential pretension could be developed as strategies to reduce compliance of dermis for its use for rotator cuff repair.
authors.affiliation: Department of Biomedical Engineering and Orthopedic and Rheumatologic Research Center, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Sambit
authors.initials: S
authors.lastname: Sahoo
authors.forename: Clay B
authors.initials: CB
authors.lastname: Greeson
authors.forename: Jesse A
authors.initials: JA
authors.lastname: McCarron
authors.forename: Ryan A
authors.initials: RA
authors.lastname: Milks
authors.forename: Amit
authors.initials: A
authors.lastname: Aurora
authors.forename: Esteban
authors.initials: E
authors.lastname: Walker
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Iannotti
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Derwin
mesh_terms: D062088:Acellular Dermis; D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D008875:Middle Aged; D019637:Orthopedic Procedures / Q000379:methods*; D017006:Rotator Cuff / Q000601:surgery*; D013536:Suture Techniques / Q000295:instrumentation*; D013537:Sutures; D013718:Tensile Strength; D055815:Young Adult