Biomechanical properties of the biceps-labral complex submitted to mechanical stress.

PURPOSE To determine biomechanical properties of the superior labrum-biceps tendon complex submitted to continuous and sudden mechanical strain. METHODS Eighteen shoulder specimens from 15 unclaimed corpses, ages ranging from 20 to 40 years, were submitted to continuous or sudden tensile tests using 3 different traction machines. Shoulders presenting signs of degenerative diseases or preexisting traumatic lesions were excluded. RESULTS Rupture of the distal portion of the long hand of the biceps occurred when stretching forces reached 290N in continuous traction and 384N in sudden traction. No labral-complex lesions were observed. CONCLUSION Either a simple continuous or a sudden uniaxial traction of the arm do not play a role in the genesis of superior labrum anterior-posterior (SLAP) lesions in the shoulder joint.