Attachment Types of the Long Head of the Biceps Tendon to the Glenoid Labrum and Their Relationships with the Glenohumeral Ligaments

Purpose: To clarify the attachment types of the long head of the biceps tendon to the glenoid labrum and their relationships with the glenoid attachment of the glenohumeral ligaments. Types of Study: Anatomic study in cadavers. Methods: Using 101 cadaver shoulders, the glenoid attachment types of the biceps tendon and the location of the glenoid origin of the glenohumeral ligaments were assessed macroscopically and then histologically on the sagittal section. Results: The glenoid attachment types of the biceps tendon were defined as entirely-posterior in 28 shoulders (27.7%), posterior-dominant in 56 shoulders (55.4%), equal in 17 shoulders (16.8%), and entirely anterior in none (0%). In all shoulders, the superior and middle glenohumeral ligaments were attached between 12 and 1 o'clock (average, 12:36 o'clock), whereas the inferior glenohumeral ligament (IGHL) showed greater variation. In the posterior-dominant and equal types, the IGHL was attached relatively high (average 2:49 o'clock for the posterior-dominant type and 1:49 o'clock for the equal type). In the entirely posterior type, the IGHL was attached low, between 4 and 5 o'clock (average, 4:32 o'clock). There was a significant difference between them (P < .001). Histologic examination showed that in the posterior-dominant and equal types, the fibers of the IGHL directly linked to the fibers of the biceps tendon, whereas in the entirely posterior type no such direct connections were observed. However, in all types, the fibers of the biceps tendon were attached to the posterior labrum. Conclusions: The labral attachment of the long head of biceps tendon was posterior regardless of its macroscopic appearance. The macroscopic attachment pattern of the biceps tendon resulted from the different attachment height of the IGHL. The attachment site of the IGHL is lower than 4 o'clock in the entirely posterior type, whereas it is higher than 4 o'clock in other types. Clinical Relevance: The present study provides useful information about the original attachment site of the IGHL during Bankart repair.