The biomechanics of the conjoined tendon(the short head of the biceps and the coracobrachialis muscle) to anterior stability was investigated in 8 cadaver shoulders.Translation tests at 90°abduction and 90°external rotation of the arm were performed by a 1.5 Kg anterior force.The position of the humeral head was monitored by a trimensional tracking device with the conjoined tendon at the original position of transfered under the subscapularis muscle;with 0 Kg,1.5 Kg Or 3 Kg loads applied on the conjoined tendon;and with the capsule intact or damaged by a Bankart lesion.the anterior displacement of the humeral head under 1.5 Kg force was significantly decreased with increasing conjoined tendon loading,especially when the conjoined tendon transfered in the capsular-damaged shoulder.