Variants of the superior labrum and labro-bicipital complex: a comparative study of shoulder specimens using MR arthrography, multi-slice CT arthrography and anatomical dissection

Abstract

The purpose of the present study was to evaluate the anatomical variability of the superior labrum and to compare the value of MR arthrography and multi-slice CT arthrography in the diagnosis of variants of the labro-bicipital complex. Forty-three human shoulder specimens (age range and mean age at death, 61-89 years and 78.3 years) were examined with the use of MR arthrography and multi-slice CT arthrography prior to joint exploration and macroscopic inspection of the superior labrum and labro-bicipital complex. Two radiologists evaluated MR and CT arthrograms, and the results were compared with macroscopic assessments. Anatomical dissection of all shoulder specimens revealed a sublabral recess in 32/43 (74%) cases. The attachment of the superior labrum was categorised as type 1 in ten (23%) cases, as type 2 in eight (19%), as type 3 in ten (23%), and as type 4 in 14 (33%) cases. One superior labrum showed detachment consistent with a superior labral anteroposterior (SLAP) type 3 lesion. On MR arthrography and CT arthrography the attachment of the superior labrum was categorised in concordance with macroscopic assessments in 79% and 84% of cases, respectively. The anteroposterior extension of sublabral recesses was accurately determined with MR and CT arthrography in 59% and 81% of cases, respectively. The attachment of the superior labrum shows considerable variability. Thus, exact depiction of variants is essential in order to avoid the false positive diagnosis of a superior labral tear (SLAP or Andrews lesion). Both, MR arthrography and multi-slice CT arthrography were effective in the detection and classification of sublabral recesses.

The anatomy of the superior labrum and biceps origin in the fetal shoulder

“…In this instance, the labrobicipital complex has been described as loosely attached to the glenoid rim in a fashion analogous to the lateral meniscus in the knee. There have been varying depths of medial extension of the cleft observed (Smith et al, 1996;Waldt et al, 2006). The incidence of this anatomical variation may be more common than previously thought (Smith et al, 1996;Kreitner et al, 1998;Waldt et al, 2006).…”

“…There have been varying depths of medial extension of the cleft observed (Smith et al, 1996;Waldt et al, 2006). The incidence of this anatomical variation may be more common than previously thought (Smith et al, 1996;Kreitner et al, 1998;Waldt et al, 2006). In a cadaveric study in which CT arthrogram and MR imaging were compared with macroscopic dissection of the labrobicipital complex, Waldt et al (2006) observed significant variability in the attachment of the superior labrum to the glenoid and a sublabral recess in 74% of cases.…”

“…The incidence of this anatomical variation may be more common than previously thought (Smith et al, 1996;Kreitner et al, 1998;Waldt et al, 2006). In a cadaveric study in which CT arthrogram and MR imaging were compared with macroscopic dissection of the labrobicipital complex, Waldt et al (2006) observed significant variability in the attachment of the superior labrum to the glenoid and a sublabral recess in 74% of cases. Other studies have demonstrated similar findings in up to 73% of specimens (Smith et al, 1996;Harzmann et al, 2003).…”

“…However, a variant of biceps-labral complex anatomy has been described. In this variant, a cleft has been observed beneath the superior and anterosuperior portion of the labrum (Cooper et al, 1992;Smith et al, 1996;Waldt et al, 2006), and this cleft has been termed as ''sublabral recess'' (Smith et al, 1996) (Fig. 1).…”

“…From a clinical standpoint, differentiating between normal and abnormal anatomy can sometimes be difficult, particularly as a loosely attached superior labrum can resemble a detachment of the superior labrum of traumatic etiology (Waldt et al, 2006).…”