title: The effect of humeral avulsion of the glenohumeral ligaments and humeral repair site on joint laxity: a biomechanical study.
abstract: OBJECTIVE
  The aims of this cadaveric study were to assess the effect of different sizes of humeral avulsion of the glenohumeral ligament (HAGL) lesions on joint laxity and to investigate any difference between repairs with anchors placed in a juxtachondral position and repairs with anchors placed in the humeral neck.
  
  
  METHODS
  Glenohumeral specimens were tested on a shoulder laxity testing system with translations applied anteriorly up to 30 N, with the joint in 60° of glenohumeral abduction. Testing was conducted in neutral rotation and under 1-Nm external rotation for 5 specimen states: intact, medium HAGL lesion (4:30 to 5:30 clock-face position), large HAGL lesion (3:30 to 6:30 clock-face position), repair with juxtachondral suture anchors, and repair with humeral neck suture anchors.
  
  
  RESULTS
  Significant increases in translation were observed between the intact and large HAGL lesion states for neutral rotation (1.46 mm [SD, 2.33 mm] at 30 N; P = .049) and external rotation (0.81 mm [SD, 0.72 mm] at 30 N; P = .005). Significant reductions in translation were also observed between the large HAGL lesion and humeral neck repair states for neutral rotation (-1.78 mm [SD, 2.23 mm] at 30 N; P = .022) and external rotation (-0.33 mm [SD, 0.37 mm] at 30 N; P = .015).
  
  
  CONCLUSIONS
  Large HAGL lesions can increase the passive motion of the glenohumeral joint in both neutral and external rotation, although these differences are small and may be difficult to measure clinically. A repair using anchors placed in the humeral neck is more likely to restore the normal restraint to anterior translation than a juxtachondral repair.
  
  
  CONCLUSIONS
  Medium HAGL lesions are unlikely to show significant increases in joint translation, and repair of large HAGL lesions should be achieved with anchors placed in the humeral neck if possible.
authors.affiliation: Department of Bioengineering, Imperial College London, London, England. dominic.southgate@imperial.ac.uk
authors.forename: Dominic F L
authors.initials: DF
authors.lastname: Southgate
authors.forename: Desmond J
authors.initials: DJ
authors.lastname: Bokor
authors.forename: Umile Giuseppe
authors.initials: UG
authors.lastname: Longo
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Wallace
authors.forename: Anthony M J
authors.initials: AM
authors.lastname: Bull
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D008023:Ligaments, Articular / Q000293:injuries* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology*; D012399:Rotation; D000070599:Shoulder Injuries; D012785:Shoulder Joint / Q000601:surgery; D053441:Suture Anchors