title: Lengthening of the subscapularis tendon as a sign of partial tearing in continuity.
abstract: BACKGROUND
  The quantification of a subscapularis tendon lesion may be difficult on magnetic resonance imaging, as well as during arthroscopic inspection. Consequently, the surgical decision of whether to only debride a degenerated tendon or to lateralize the more intact tendon portion may be arbitrary. This study aims to quantify the length of the subscapularis tendon as a sign of partial tendon tearing.
  
  
  METHODS
  We retrospectively identified 92 magnetic resonance arthrography studies of suspected rotator cuff lesions obtained 3 months before shoulder arthroscopy. The myotendinous junction was identified, and the subscapularis tendon and muscle lengths were measured. Findings on arthroscopy performed later were used as the diagnostic gold standard for tendon integrity and compared with the magnetic resonance data.
  
  
  RESULTS
  Arthroscopy showed an intact subscapularis tendon in 43 patients, tendinopathy in 21 patients, and a partial rupture in 28 patients. The mean subscapularis tendon lengths were 40 mm in cases of intact subscapularis musculotendinous units, 45 mm in cases of tendinopathy, and 53 mm in cases of partial tears, whereas the mean subscapularis muscle lengths were 105 mm, 94 mm, and 95 mm, respectively, in these groups.
  
  
  CONCLUSIONS
  Partial tears of the subscapularis tendon lead to muscle shortening by approximately 10% and elongation of the tendon by approximately 32%, which may be interpreted as muscle retraction and a tendon rupture in continuity. If the subscapularis tendon has an apparent length of greater than 60 mm, the probability of a tear is 98%. Determination of the tendon length may therefore be a useful additional tool to quantify the integrity of the subscapularis tendon and degree of myotendinous retraction.
authors.affiliation: Department of Orthopaedics, Balgrist University Hospital, University of Zürich, Zürich, Switzerland. Electronic address: dominik.meyer@balgrist.ch.
authors.forename: Dominik C
authors.initials: DC
authors.lastname: Meyer
authors.affiliation: Department of Orthopaedics, Balgrist University Hospital, University of Zürich, Zürich, Switzerland.
authors.forename: Stefan M
authors.initials: SM
authors.lastname: Zimmermann
authors.affiliation: Department of Orthopaedics, Balgrist University Hospital, University of Zürich, Zürich, Switzerland.
authors.forename: Karl
authors.initials: K
authors.lastname: Wieser
authors.affiliation: Department of Radiology, Balgrist University Hospital, University of Zürich, Zürich, Switzerland.
authors.forename: Susanne
authors.initials: S
authors.lastname: Bensler
authors.affiliation: Department of Orthopaedics, Balgrist University Hospital, University of Zürich, Zürich, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Gerber
authors.affiliation: Department of Orthopaedics, Balgrist University Hospital, University of Zürich, Zürich, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Germann
mesh_terms: D001182:Arthroscopy / Q000379:methods; D005260:Female; D006801:Humans; D022125:Lacerations / Q000175:diagnosis* / Q000601:surgery; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D012189:Retrospective Studies; D017006:Rotator Cuff / Q000473:pathology*; D000070636:Rotator Cuff Injuries; D012421:Rupture / Q000175:diagnosis / Q000601:surgery; D052256:Tendinopathy / Q000175:diagnosis / Q000601:surgery; D013708:Tendon Injuries / Q000175:diagnosis* / Q000601:surgery
keywords: MR arthrography; Rotator cuff tear; arthroscopy; muscle shortening; myotendinous retraction; partial subscapularis lesion; tendon lengthening