Identification of the reference length (L0) for the coracohumeral ligament. Reference length was the length at which the angle-strain curve of the ligament started to indicate a sudden decrease in strain. Photographs (a), (b), (c) indicate the coracohumeral ligament during external rotation at 0° elevation in the scapula plane of the glenohumeral joint; (a) the slack ligament, (b) the ligament at L0, and (c) tight ligament. This arrow is point of change in strain ratio from slack to tight in Figure 4. True strain of the joint capsule can be obtained from this point.