Subscapularis

This is “…the secondary landmark of shoulder arthroscopy”. [7] It extends between its origin at the humeral head to the lesser tuberosity of the humerus. [6] The superior border of the tendon is intra-articular, “…lying in a recess between the superior and middle glenohumeral ligaments”. [8]

Snyder [6] described the intra-articular appearance of the tendon, with it most commonly having “…a smoothly rolled edge…” Variants include the leading edge having a split or bifid type appearance, with no associated fraying and a prevalence of 3%. [6]

In an arthroscopic study, Wright et al [74] reported only 26% ± 11% of the entire tendon could be seen through arthroscopy. This represents 44% of the mean height of the tendon. [74] Poor visualisation of the tendon occurs as a result of its position in which it covered by the middle and inferior glenohumeral ligaments. [74]

A separate arthroscopic study showed the average height and width of the intra-articular subscapularis tendon to be 5mm and 11mm respectively. [75]

From our study:

A subscapularis tendon was noted in all 132 cases, with all having “…a smoothly rolled edge…” [6] A 3% prevalence of a bifid subscapularis tendon noted in the present study is similar to that previously documented. [6] Examples of previously undescribed double and triple subscapularis tendons were also noted.

Table 15 – Prevalence and variation in the appearance of the Subscapularis tendon

Prevalence	No.	%
Present	132	100
Absent	0	0
Appearance – smooth rolled up edges
Present	132	100
Absent	0	0
Prevalence of Variations
Present	7	5.3
Absent	125	94.7
Variation in the appearance of the Subscapularis tendon
Split / Bifid subscapularis tendon	3	3
Double tendon appearance	2	2
Triple tendon appearance	2	2