title: Evidence of healing of partial-thickness rotator cuff tears following arthroscopic augmentation with a collagen implant: a 2-year MRI follow-up.
abstract: BACKGROUND
  partial-thickness rotator cuff tears frequently enlarge due to increased local strain and often progress to full-thickness tears. Studies suggest the addition of new tendinous tissue to injured cuff tendons would significantly decrease peak strain, possibly protecting against tear progression. The aim of this study was to assess the ability of a highly-porous collagen implant to induce new tissue formation and limit tear progression when placed on the bursal surface of partial-thickness cuff tears.
  
  
  METHODS
  following arthroscopic subacromial decompression, the implant was attached to the bursal surface of the supraspinatus tendon in a prospective series of 13 consecutive patients with intermediate - (3-6 mm) to high-grade (>6 mm) partial - thickness cuff tears (5 articular, 3 bursal, 5 intra-substance). Tendon thickness, defect size, and tendon quality were evaluated using magnetic resonance imaging (MRI) preoperatively and at 3, 6, 12, and 24 months postoperatively. Clinical outcomes were assessed using the Constant and American Shoulder and Elbow Society scores at the same preoperative and follow-up times. All 13 patients completed all follow-up exams (mean length of follow-up 27.0 months, range 23.3-32.0); no patients were lost to follow-up.
  
  
  RESULTS
  the implant induced significant new tissue formation in all patients by 3 months (mean increase in tendon thickness 2.2 ± 0.26 mm). This tissue matured over time and became radiologically indistinguishable from the underlying tendon. The partial-thickness cuff tears showed consistent filling of the defects, with complete healing in 7 patients at 12 months, and a progressive improvement in tendon quality in the remaining patients. No tear progression was observed by MRI in any of the patients at 24 months. All clinical scores improved significantly over time. At 24 months, 12 of 13 patients (92%) had satisfactory or better results.
  
  
  CONCLUSIONS
  the results of this clinical study demonstrated the ability of a highly-porous collagen implant to induce new tendon-like tissue formation and create an environment conductive to the healing of partial-thickness cuff tears.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine and Health Sciences, Macquarie University, Australia.
authors.forename: Desmond John
authors.initials: DJ
authors.lastname: Bokor
authors.affiliation: Department of Orthopaedic Surgery, Royal North Shore Hospital, St Leonards, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Sonnabend
authors.affiliation: Alfred Imaging & Alfred Advanced Sports Imaging Centre, Drummoyne, Australia.
authors.forename: Luke
authors.initials: L
authors.lastname: Deady
authors.affiliation: Sydney Shoulder Specialists, St. Leonards, Australia.
authors.forename: Ben
authors.initials: B
authors.lastname: Cass
authors.affiliation: Sydney Shoulder Specialists, St. Leonards, Australia.
authors.forename: Allan
authors.initials: A
authors.lastname: Young
authors.affiliation: Rotation Medical, Inc, Plymouth, USA.
authors.forename: Craig
authors.initials: C
authors.lastname: Van Kampen
authors.affiliation: College of Veterinary Medicine Michigan State University, East Lansing, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Arnoczky
keywords: MRI; collagen implant; partial-thickness rotator cuff tear; tendon healing