title: Effect of Arthroscopic Stabilization on In Vivo Glenohumeral Joint Motion and Clinical Outcomes in Patients With Anterior Instability.
abstract: BACKGROUND
  Glenohumeral joint (GHJ) dislocations are common, and the resulting shoulder instability is often treated with arthroscopic stabilization. These procedures result in favorable clinical outcomes, but abnormal GHJ motion may persist, which may place patients at risk for developing osteoarthritis. However, the effects of shoulder instability and arthroscopic stabilization on GHJ motion are not well understood.
  
  
  OBJECTIVE
  GHJ motion is significantly influenced by anterior instability and arthroscopic stabilization, but postsurgical measures of GHJ motion are not different from those of control subjects.
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  In vivo GHJ motion was measured by applying a computed tomographic model-based tracking technique to biplane radiographic images acquired during an apprehension test in healthy control subjects (n = 11) and anterior instability patients (n = 11). Patients were tested before surgery and at 6 months after surgery. Control subjects were tested once. Shoulder strength, active range of motion (ROM), and the Western Ontario Shoulder Instability (WOSI) index were also measured.
  
  
  RESULTS
  Before surgery, the humerus of the instability patients during the apprehension test was located significantly more anteriorly on the glenoid (7.9% of glenoid width; 2.1 mm) compared with that of the controls (P = .03), but arthroscopic stabilization moved this joint contact location posteriorly on the glenoid (4.7% of glenoid width; 1.1 mm; P = .03). After surgery, GHJ excursion during the apprehension test was significantly lower (14.7% of glenoid width; 3.6 mm) compared with presurgical values (19.4% of glenoid width; 4.7 mm; P = .01) and with that of the controls (22.4% of glenoid width; 5.7 mm; P = .01). The external and internal rotation strength of patients was significantly lower than that of the controls before surgery (P < .05), but differences in strength did not persist after surgery (P > .17). External rotation ROM in patients was significantly lower than that in control subjects both before and after arthroscopic stabilization (P < .01). The WOSI score improved significantly, from 48.3 ± 13.1 presurgery to 86.3 ± 16.5 after surgery (P = .0002).
  
  
  CONCLUSIONS
  In patients with anterior instability, arthroscopic stabilization significantly improves measures of strength, ROM, and clinical outcome. However, GHJ excursion is not fully restored to levels seen in the control subjects.
  
  
  CONCLUSIONS
  Although arthroscopic stabilization satisfactorily restores most clinical outcome measures, GHJ excursion and external rotation ROM remain compromised compared with healthy control subjects and may contribute to the development of osteoarthritis in patients with anterior instability.
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, Michigan, USA cpeltz1@hfhs.org.
authors.forename: Cathryn D
authors.initials: CD
authors.lastname: Peltz
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Baumer
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Veronica
authors.initials: V
authors.lastname: Mende
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: Ramo
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Nima
authors.initials: N
authors.lastname: Mehran
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Vasilios
authors.initials: V
authors.lastname: Moutzouros
authors.affiliation: Bone and Joint Center, Henry Ford Health System, Detroit, Michigan, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bey
mesh_terms: D000293:Adolescent; D000328:Adult; D001182:Arthroscopy / Q000379:methods*; D016022:Case-Control Studies; D006801:Humans; D006811:Humerus; D007593:Joint Instability / Q000601:surgery*; D017063:Outcome Assessment, Health Care; D016059:Range of Motion, Articular; D012399:Rotation; D012540:Scapula; D012783:Shoulder Dislocation / Q000601:surgery*; D012785:Shoulder Joint / Q000601:surgery*; D055815:Young Adult
keywords: anterior instability; arthroscopic stabilization; clinical outcomes; glenohumeral joint motion