title: The influence of different footprint preparation techniques on tissue regeneration in rotator cuff repair in an animal model.
abstract: BACKGROUND
  Rotator cuff tears are common diseases of the upper extremity. There are no recommendations to the surgeon on how to prepare the footprint to ensure optimal tendon-to-bone healing. However, biologic augmentation using stem cells and growth factors is considered to encourage the healing process of the tendon. The aim of the study was to investigate the biomechanical and histological outcome of different footprint preparations in rotator cuff repair.
  
  
  METHODS
  One hundred and eighty-nine Sprague-Dawley rats were randomly assigned to either spongialization, radiofrequency ablation or an untreated control group. Rats were killed after 1 or 7 weeks for histological evaluation or after 7 weeks for biomechanical testing.
  
  
  RESULTS
  Histological evaluation showed better tissue organization in the control and spongialization group compared to the radiofrequency ablation group. The highest collagen I to collagen III quotient was found in the control group, followed closely by the spongialization group. Measured quotients showed a decrease in the values after 1 week compared to the values after 7 weeks, except in the radiofrequency ablation group, where an increase was detected. A significant difference was found in the load to failure test comparing the radiofrequency ablation group to the spongialization group (p= 0.0409) and control group (p= 0.014), but not comparing the spongialization group to the control group (p= 0.2456).
  
  
  CONCLUSIONS
  The results of this study suggest that spongialization of the footprint before attaching the torn supraspinatus tendon can lead to better structural properties and higher quality of tendon-to-bone restoration at the insertion area when compared with radiofrequency ablation.
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Munich, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Ficklscherer
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Munich, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Serr
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Munich, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Loitsch
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Munich, Germany.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Niethammer
authors.affiliation: Department of Orthopedic Sports Surgery, St. Josef-Hospital, Ruhr-University Bochum, Bochum, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Lahner
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Munich, Germany.
authors.forename: Matthias F
authors.initials: MF
authors.lastname: Pietschmann
authors.affiliation: Department of Orthopedic Surgery, University Hospital of Munich (LMU), Munich, Germany.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Müller
keywords: rotator cuff repair; tendon-to-bone healing; tissue engineering