We studied 100 fresh human shoulders in cadavers (mean age 76 years), and the range of passive abduction (RPA) in 100 volunteers with normal shoulders and in 90 patients with instability of the joint, over a period of six years.The anatomical and clinical findings showed that passive abduction occurs within the glenohumeral joint only, is controlled by the inferior glenohumeral ligament and has a constant value in 95% of both shoulders in normal subjects. In patients with instability, 85% showed an RPA of over 105° with 90°i n the contralateral shoulder. In the remaining patients a strongly positive apprehension test suggested a diagnosis of instability.An RPA of more than 105° is associated with lengthening and laxity of the inferior glenohumeral ligament. The sulcus and drawer tests 1,2 for the assessment of laxity of the shoulder are performed in positions of the joint in which the ligaments are relaxed. They examine a complex situation and not the laxity of a particular ligament. Laxity of the inferior glenohumeral ligament (IGHL) is an essential factor contributing to both atraumatic and multidirectional instability of the shoulder. 2,3 Some authors 4 believe that it may also be present in patients with instability after injury. Clinical methods of assessing such laxity have not been described previously.We have tested the role of the IGHL in the restriction of movement of the glenohumeral joint (GHJ), and investigated the possibility of a clinical assessment of its laxity. Patients and MethodsThere were three parts to the study: 1) in cadavers; 2) in volunteers; and 3) in patients with instability of the shoulder after injury. Study in cadavers. We obtained 100 fresh normal human shoulders, 68 from women and 32 from men, with a mean age of 76 years (61 to 82). The scapula was fixed on a rigid frame with its medial edge vertical and the blade lying at an angle of 30° anterior to the coronal plane to reproduce the normal position along the thorax. All the muscles of the GHJ were removed leaving the ligaments intact and the joint cavity closed.The maximum range of movement in all planes was measured using a goniometer. The landmark used to check the position of the arm was a line from the posterior edge of the acromion to the lateral epicondyle. The structures responsible for limitation of movement were observed. Measurements were made in neutral rotation. The ranges of abduction and elevation were recorded before and after section of the IGHL. Study in volunteers. There were 100 volunteers, 63 men and 37 women with a mean age of 28 years (24 to 38). Clinical. In order to measure the range of passive abduction (RPA), the physician stood behind the patient with his Fig. 1 Photograph showing the technique of the test. The forearm of the physician holds the shoulder girdle firmly in the lower position and the other hand lifts the patient's arm up in the frontal plane. In this case the hyperabduction test is negative.