Relationship between subscapularis tears and injuries to the biceps pulley

The most important finding of the present study was that in approximately 10% of cases, the bicipital reflection pulley remains intact even in the case of subscapularis tear, confirming our hypothesis. This study also showed that in cases of subscapularis tear, the SGHL/CHL complex remains intact in 25% of cases with a LHBT usually centred. Nevertheless, we observed in these patients macroscopic tendinosis or a tear of the LHBT due to a lesion of the medial wall of the bicipital sheath below the SGHL/CHL complex.

Cadaveric studies have shown the CHL to be the key ligament responsible for keeping the LHBT aligned within the tubercular groove [10, 25]. Werner et al. [32] and Habermeyer et al. [14] found that the orientation of the fibres of the SGHL towards the LHBT seemed to withstand anterior shearing forces in the lateral rotator interval, indicating that the most important function of the SGHL was the stabilization of the LHBT in its intra-articular course.

The findings of the current study have several important implications. A standard assessment of the bicipital groove with a 30° arthroscope through the posterior portal seems insufficient for fully evaluating the LHBT. Previous authors have reported that the vast majority of clinically relevant LHBT and bicipital groove lesions occur proximally and may be found and subsequently treated with standard diagnostic arthroscopic techniques [11‐13, 18]. Some authors have pointed to the utility of pulling the LHBT into the joint with an arthroscopic probe through the anterior working portal. However, this manoeuvre appears insufficient based on the findings in the current study as medial sidewall lesions would be missed. Several recent researches have called into question whether arthroscopy provides an adequate view of the LHBT and bicipital groove [20, 26, 27]. Consequently, when a subscapularis tear is suspected and the SGHL/CHL complex appears normal during arthroscopic assessment, the LHBT in its intertubercular groove and the medial wall of the groove must be checked. This assessment can be performed either with an intra-articular view with the usage of a 70° arthroscope that significantly increases the length of bicipital groove visualized [24] or after opening the transverse ligament with an anterolateral extra-articular inspection (Fig. 4).

The subscapularis has a crucial role in shoulder function. First, in combination with the anterior supraspinatus, the upper subscapularis is the anterior insertion of the rotator cable [7, 29]. Second, the subscapularis stabilizes the LHBT. In an anatomical, clinical, and MRI study, Sakurai et al. [23] showed that most of the pathologic changes of the subscapularis tendon occurred on the articular side of the subscapularis tendon. In the specimens with such an articular-sided incomplete tear, the height of the medial wall of the bicipital groove was decreased, potentially being more susceptible to medial subluxation or dislocation of the LHBT. Arai et al. [1] described the “tendinous slip”. Anatomically, the most superior part of the subscapularis tendon is attached to the upper margin of the lesser tuberosity and extends as a thin tendinous slip to the fovea capitis of the humerus. The SGHL runs spirally along the biceps tendon, and histologically the SGHL attaches to the tendinous slip. The SGHL attaches to the tendinous slip of the subscapularis insertion as if it was a fold of loose connective tissue and directly supports the LHBT. The CHL, which is also a part of the same loose connective tissue, is considered to provide tension to the SGHL. The most superior insertion point of the subscapularis tendon supports the LHBT from behind the SGHL. Bennett confirmed this with an arthroscopic study that shows that the outer surface of the subscapularis tendon is intimately associated with the CHL and the SGHL with interdigitating fibres [2]. This pulley system protects the biceps tendon from subluxation. Third, it is the key to anterior elevation [4]. Finally, it has been demonstrated that subscapularis repair provides good long-term results and preservation of shoulder function [6].

According to previous studies, simple debridement, biceps tenotomy, and tenodesis concomitant to rotator cuff repair all have good clinical/functional outcomes and patient satisfaction [5, 21]. However, these studies did not focus specifically on subscapularis pathology. The results of the present study demonstrate that an action on the biceps is indicated in case of a subscapularis tear. Given that more than 90% of patients with a subscapularis tear have associated LHBT lesions or instability, we believe that preservation of the intra-articular biceps will jeopardize a subscapularis tendon repair. Indeed, Edwards et al. demonstrated that the outcomes of subscapularis repair were inferior when the biceps was preserved. Consequently, simple debridement of the biceps does not seem to be a reasonable option in the setting of subscapularis repair.

This study has several limitations. First, we did not correlate arthroscopic findings with preoperative images. Nevertheless, magnetic resonance imaging has low sensitivity, specificity, PPV, and NPV to detect this condition and arthroscopic evaluation remains the gold standard [19]. Second, the surgeries were performed by a large group of surgeons, leading to some missing values. Third, a few of the criteria used during dynamic evaluation, such as “stretch” or “subluxation”, are subjective and do not represent by definition a pathological condition and might have been interpreted differently by other surgeons. However, they are part of commonly used descriptions and have been classified in the present study under the appreciation of senior surgeons. Finally, we do not have long-term clinical outcomes or healing data to determine the best surgical option related to biceps pathology and whether subscapularis repair is systematically required. However, this study analysed prospectively the prevalence of lesions of LHBT and adjacent structures in a large cohort of patients with a subscapularis tear. The videos of all procedures were analysed by four senior surgeons, and discrepancies regarding analysis of videos were observed in only 11 cases. Although previous studies have described pathology of the LHBT, the correlations observed during this study between biceps pathology and lesions of the sheath, pulley, and SGHL/CHL complex are unique and the findings have several important implications including the necessity to address the biceps.