title: Biomechanical comparison of expanded polytetrafluoroethylene (ePTFE) and PTFE interpositional patches and direct tendon-to-bone repair for massive rotator cuff tears in an ovine model.
abstract: BACKGROUND
  Massive irreparable rotator cuff tears are a difficult problem. Modalities such as irrigation and debridement, partial repair, tendon transfer and grafts have been utilized with high failure rates and mixed results. Synthetic interpositional patch repairs are a novel and increasingly used approach. The present study aimed to examine the biomechanical properties of common synthetic materials for interpositional repairs in contrast to native tendon.
  
  
  METHODS
  Six ovine tendons, six polytetrafluoroethylene (PTFE) felt sections and six expanded PTFE (ePTFE) patch sections were pulled-to-failure to analyze their biomechanical and material properties. Six direct tendon-to-bone surgical method repairs, six interpositional PTFE felt patch repairs and six interpositional ePTFE patch repairs were also constructed in ovine shoulders and pulled-to-failure to examine the biomechanical properties of each repair construct.
  
  
  RESULTS
  Ovine tendon had higher load-to-failure (591 N) and had greater stiffness (108 N/mm) than either PTFE felt (296 N, 28 N/mm) or ePTFE patch sections (323 N, 34 N/mm). Both PTFE felt and ePTFE repair techniques required greater load-to-failure (225 N and 177 N, respectively) than direct tendon-to-bone surgical repairs (147 N) in ovine models.
  
  
  CONCLUSIONS
  Synthetic materials lacked several biomechanical properties, including strength and stiffness, compared to ovine tendon. Interpositional surgical repair models with these materials were significantly stronger than direct tendon-to-bone model repairs.
authors: University of New South Wales, Sydney, NSW, Australia.
authors: Andrew Dj
authors: ADj
authors: McKeown
authors: University of New South Wales, Sydney, NSW, Australia.
authors: Rebekah F
authors: RF
authors: Beattie
authors: University of New South Wales, Sydney, NSW, Australia; Orthopaedic Research Institute, St George Hospital Campus, Kogarah, NSW, Australia.
authors: George Ac
authors: GA
authors: Murrell
authors: University of New South Wales, Sydney, NSW, Australia; Orthopaedic Research Institute, St George Hospital Campus, Kogarah, NSW, Australia.
authors: Patrick H
authors: PH
authors: Lam
keywords: PTFE patch; biomechanics; interpositional patch; irreparable rotator cuff; ovine; synthetic patch repair