title: Subscapularis muscle function and structure after total shoulder replacement with lesser tuberosity osteotomy and repair.
abstract: BACKGROUND
  Recent studies have suggested that tenotomy and repair of the subscapularis tendon carried out for anterior approaches to the shoulder can be followed by failure of the tendon repair and by changes resulting in permanent loss of subscapularis function. We hypothesized that release of the subscapularis with use of a superficial osteotomy of the lesser tuberosity followed by repair of the two opposing bone surfaces would lead to consistent bone-to-bone healing, which would be possible to monitor radiographically, and would lead to satisfactory clinical and structural outcomes.
  
  
  METHODS
  Thirty-nine shoulders in thirty-six consecutive patients who, at an average age of fifty-seven years, had undergone total shoulder replacement through an anterior approach involving an osteotomy of the lesser tuberosity were evaluated at an average of thirty-nine months. Assessment included a standardized interview and physical examination, scoring according to the system described by Constant and Murley, and imaging with conventional radiography and computed tomography to assess healing of the osteotomy site and changes in the subscapularis.
  
  
  RESULTS
  The osteotomized tuberosity fragment healed in an anatomical position in all shoulders, and no cuff tendon ruptures were observed. At the time of follow-up, thirty-three (89%) of thirty-seven shoulders evaluated with a belly-press test had a negative result and twenty-seven (75%) of thirty-six shoulders evaluated with a lift-off test had an unequivocally normal result. Fatty infiltration of the subscapularis muscle increased after the operation (p < 0.0001) and was at least stage two in eleven (32%) of thirty-four shoulders. The fatty infiltration had progressed by one stage in eight (24%) of the thirty-four shoulders, by two stages in five shoulders (15%), and by three stages in two shoulders (6%).
  
  
  CONCLUSIONS
  Osteotomy of the lesser tuberosity provides an easy anterior approach for total shoulder replacement and is followed by consistent bone-to-bone healing, which can be monitored, and good subscapularis function. In the presence of documented anatomical healing of the osteotomy site, postoperative fatty infiltration of the subscapularis muscle remains unexplained and needs to be investigated further as it is associated with a poorer clinical outcome.
authors.affiliation: Department of Orthopedic Surgery, Balgrist Hospital, Forchstrasse 340, 8032 Zurich, Switzerland. christian.gerber@balgrist.ch
authors.forename: Christian
authors.initials: C
authors.lastname: Gerber
authors.forename: Edward H
authors.initials: EH
authors.lastname: Yian
authors.forename: Christian A W
authors.initials: CA
authors.lastname: Pfirrmann
authors.forename: Matthias A
authors.initials: MA
authors.lastname: Zumstein
authors.forename: Clément M L
authors.initials: CM
authors.lastname: Werner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D006811:Humerus / Q000601:surgery; D007595:Joint Prosthesis; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000601:surgery*; D010027:Osteotomy / Q000379:methods; D016059:Range of Motion, Articular; D012785:Shoulder Joint / Q000503:physiopathology / Q000601:surgery*