title: The Influence of Surgical Stabilization on Glenohumeral Abduction Using 3-Dimensional Computed Tomography in Patients With Shoulder Instability.
abstract: This study compared the amount of glenohumeral abduction during arm abduction in the affected and unaffected shoulders of 3 groups of patients with shoulder instability: failed surgical stabilization, successful surgical stabilization, and unstable shoulder with no prior surgical intervention.
  
  
  
  All patients underwent bilateral shoulder computed tomography scans in 3 positions: 0° of abduction and 0° of external rotation (0-0 position), 30° of abduction and 30° of external rotation (30-30 position), and arms maximally abducted (overhead position). Three-dimensional computed tomography reconstruction was performed for both shoulders in all 3 positions. A specialized coordinate system marked specific points and directions on the humerus and glenoid of each model. These coordinates were used to calculate the glenohumeral abduction for the normal and affected sides in the 0-0, 30-30, and overhead positions.
  
  
  
  Thirty-nine patients with shoulder instability were included, of whom 14 had failed surgical repairs, 10 had successful surgical repairs, and 15 had unstable shoulders with no prior surgical intervention. In the overhead position, patients with failed surgical intervention had significantly less glenohumeral abduction in the failed shoulder (95.6° ± 12.7°) compared with the normal shoulder (101.5° ± 12.4°, P = .02). Patients with successfully stabilized shoulders had significantly less glenohumeral abduction in the successfully stabilized shoulder (93.6° ± 10.8°) compared with the normal shoulder (102.1° ± 12.5°, P = .03). Unstable shoulders with no prior surgical intervention (102.1° ± 10.3°) did not differ when compared with the normal shoulders (101.9° ± 10.9°, P = .95).
  
  
  
  Surgical intervention, regardless of its success, limits the amount of abduction at the glenohumeral joint.
  
  
  
  Level III, retrospective comparative study.
authors.affiliation: Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.
authors.forename: Neil K
authors.initials: NK
authors.lastname: Bakshi
authors.affiliation: Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.
authors.forename: Omar F
authors.initials: OF
authors.lastname: Jameel
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.
authors.forename: Zachary F
authors.initials: ZF
authors.lastname: Merrill
authors.affiliation: Department of Bioengineering, University of Pittsburgh, Pittsburgh, Pennsylvania, U.S.A.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Debski
authors.affiliation: Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, Michigan, U.S.A.. Electronic address: sekiya@med.umich.edu.
authors.forename: Jon K
authors.initials: JK
authors.lastname: Sekiya
mesh_terms: D000293:Adolescent; D000328:Adult; D001132:Arm; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006811:Humerus / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional; D007593:Joint Instability / Q000000981:diagnostic imaging* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012399:Rotation; D012540:Scapula / Q000000981:diagnostic imaging*; D012785:Shoulder Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed; D055815:Young Adult