title: Anatomic and radiographic analysis of arthroscopic tack placement into the superior glenoid.
abstract: OBJECTIVE
  To anatomically and radiographically describe tack location within the anterosuperior (AS) and posterosuperior (PS) aspects of the glenoid when performing simulated repairs of type II SLAP lesions.
  
  
  METHODS
  Cadaveric anatomic and radiographic analysis.
  
  
  METHODS
  Arthroscopy was performed on 7 fresh-frozen cadaveric shoulders and bioabsorbable tacks were placed in the AS and PS aspects of the glenoid to simulate repair of a type II SLAP lesion. The PS tack was placed through an accessory portal 1 cm lateral and 1 cm anterior to the posterolateral corner of the acromion. Dissection was then performed, and the incision made in the rotator cuff when creating the posterolateral accessory portal (PLAP) was identified and measured. Tack location within the glenoid was visually studied after removal of all soft tissues and recorded as being either completely within bone or partially within bone. The tacks were recannulated with guide pins and 3 radiographs were then taken of each specimen (true anteroposterior, axillary, and en face glenoid views) and angles of entry determined. In addition, the angle of deviation from the orthogonal at the point of entry of each tack was measured on the en face glenoid view.
  
  
  RESULTS
  The average incision made in the rotator cuff for creation of the PLAP measured 10.3 mm in maximum diameter. In 6 of 7 specimens, this incision was made through muscle and not tendon. Seven of 7 AS tacks were completely within bone, and only 5 of 7 PS tacks remained completely within bone. On the true anteroposterior view, the average angle of entry from the vertical for the AS tack was 64 degrees. For the PS tack, this angle measured 86 degrees. On the axillary view, the angle of placement from the coronal averaged 22 degrees for the AS tack and 42 degrees for the PS tack. For the en face glenoid view, the angle of entry from the vertical was 34 degrees for the AS tack and 93 degrees for the PS tack. Lastly, the angle of deviation from the orthogonal on the en face glenoid view was 12 degrees and 35 degrees for the AS and PS tacks, respectively. This difference was statistically significant at P <.001.
  
  
  CONCLUSIONS
  This study provides quantitative data on the angle of placement and location of tacks within the superior glenoid when performing repairs of type II SLAP lesions. It also shows the PLAP to be a safe portal for the placement of devices into the posterosuperior aspect of the glenoid. Furthermore, the data show the AS tack to be more reliably placed than the PS tack.
authors.affiliation: Department of Orthopaedic Surgery, Baylor College of Medicine, Houston, Texas, USA.
authors.forename: Marshall L
authors.initials: ML
authors.lastname: Trusler
authors.forename: William J
authors.initials: WJ
authors.lastname: Bryan
authors.forename: Omer A
authors.initials: OA
authors.lastname: Ilahi
mesh_terms: D020341:Absorbable Implants; D001182:Arthroscopy / Q000379:methods*; D006801:Humans; D017746:Joint Capsule / Q000000981:diagnostic imaging / Q000293:injuries; D007593:Joint Instability / Q000601:surgery*; D009984:Orthopedic Fixation Devices; D011859:Radiography; D017006:Rotator Cuff / Q000033:anatomy & histology / Q000601:surgery; D000070636:Rotator Cuff Injuries; D012540:Scapula / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000601:surgery; D012785:Shoulder Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000601:surgery; D016896:Treatment Outcome