Deformation and strain characteristics along the length of the anterior band of the inferior glenohumeral ligament

Efficacious surgical treatment of anterior glenohumeral instability often r equires repair of the anteroinferior capsulolabral structures, including th e glenoid origin of the anterior band of the inferior glenohumeral ligament . Rupture in this location, the Bankart lesion, may be accompanied by nonre coverable stretching of the anterior band. The purpose of this study was to evaluate the amount and location of nonrecoverable stretching with tensile testing. Twelve glenoid-soft tissue-humerus complexes from fresh-frozen gl enohumeral joints were studied by means of a custom jig, an Instron machine , and a video digitizing system. The joints were positioned to simulate tha t known to cause apprehension for anterior instability. Nonrecoverable defo rmation differed along the length of the anterior band but was slight in al l locations. For those that failed at the glenoid insertion region, the mea n nonrecoverable deformation was 0.10 +/- 0.16 mm (mean +/- SEM) at the bon e-labral junction of the glenoid insertion region and 0.38 +/- 0.23 mm at t he labral-ligament junction of the glenoid insertion region. It was 0.53 +/ - 0.23 mm at the ligament midsubstance and 0.04 +/- 0.10 mm at the humeral insertion region. For those that failed at the glenoid insertion region, th e nonrecoverable stretching was 1.4% +/- 7.9% at the bone-labral junction o f the glenoid insertion region and 3.5% +/- 2.0% at the labral-ligament jun ction of the glenoid insertion region. It was 2.3% +/- 1.1% at the ligament midsubstance and 0.0% +/- 1.4% at the humeral insertion region. Rupture of the anterior band resulted in little nonrecoverable stretching at both the site of failure and elsewhere along the length, remote from the failure si te. Surgical repairs after initial dislocation may restore the length of th e anterior band of the inferior glenohumeral ligament with little shortenin g.