Superior labrum and labral-bicipital complex: MR imaging with pathologic-anatomic and histologic correlation

The purpose of this study was to analyze the anatomic relationship between the superior labrum, the superior glenoid rim, the superior glenohumeral ligament, and the long head of the biceps tendon.

Seventeen cadaveric shoulder specimens underwent axial, oblique coronal, and oblique sagittal MR imaging on a 1.5-T imager. Unenhanced proton density- and T2-weighted spin-echo images with and without fat suppression, and T1-weighted fat-suppressed spin-echo images after intraarticular injection of gadolinium, were obtained of each specimen. The shoulders were then frozen and sectioned into 4-mm-thick slices, either transversely or oblique coronally. After gross anatomic correlation, histologic analysis was performed on 32 sections.

A sublabral recess was present in 12 (71%) of 17 shoulders. MR arthrography was significantly better at showing the sublabral recess than was unenhanced MR imaging. Histologically, the synovial recess in all cases was covered by synovial lining cells. Intralabral altered histologic patterns were found in 20 (63%) of 32 labral sections. In addition to signs of degeneration, five sections of two specimens showed proliferating fibroblasts and vessels, as well as fibrosis, suggesting trauma. The presence or absence of altered intralabral histologic patterns was better assessed with T1-weighted fat-suppressed arthrograms than with unenhanced MR images. We found a close association grossly and histologically between the superior labrum and the biceps tendon.

The attachment of the superior glenoid labrum to the glenoid rim shows great variability. In MR imaging, an overlap appears to exist between physiologic recesses of the superior labrum and a type 2 superior labrum anterior-posterior lesion. T1-weighted fat-suppressed MR arthrograms provided the best view of the superior labrum and the labral-bicipital complex.