The anterior band of the inferior glenohumeral ligament - Assessment of its permanent deformation and the anatomy of its glenoid attachment

Surgical treatment for traumatic, anterior glenohumeral instability require s repair of the anterior band of the inferior glenohumeral ligament, usuall y at the site of glenoid insertion, often combined with capsuloligamentous plication. In this study, we determined the mechanical properties of this l igament and the precise anatomy of its insertion into the glenoid in fresh- frozen glenohumeral joints of cadavers, Strength was measured by tensile te sting of the glenoid-soft-tissue-humerus (G-ST-H) complex. Two other specim ens of the complex were frozen in the position of apprehension, serially se ctioned perpendicular to the plane containing the anterior and posterior ri ms of the glenoid, and stained with Toluidine Blue, On tensile testing, eight G-ST-H complexes faded at the site of the glenoid insertion, representing a Bankart lesion, two at the insertion into the hu merus, and two at the midsubstance, For those which failed at the glenoid a ttachment the mean yield load was 491.0 N and the mean ultimate load, 585.0 N. At the glenoid region, stress at yield was 7.8 +/- 1.3 MPa and stress a t failure, 9.2 +/- 1.5 MPa, The permanent deformation, defined as the diffe rence between yield and ultimate deformation, was only 2.3 +/- 0.8 mm. The strain at yield was 13.0 +/- 0.7% and at failure, 15.4 +/- 1.2%; therefore permanent strain was only 2.4 +/- 1.1%. Histological examination showed that there were two attachments of the ante rior band of the inferior glenohumeral ligament at the site of the glenoid insertion. In one, poorly organised collagen fibres inserted into the labru m, In the other, dense collagen fibres were attached to the front of the ne ck of the glenoid.