Superior labral dimension of the glenohumeral joint on direct MR arthrography (MRA): Relationship with presence of SLAP

Abstract

PURPOSE To evaluate the relationship between superior labral dimension of the glenohumeral joint on direct MRA and presence of SLAP lesion

MATERIALS AND METHODS Direct MRA of the shoulder was performed in 296 patients (300 shoulders) for chronic pain or instability, who underwent arthroscopic shoulder surgery. Arthroscopic operation records of all patients were reviewed. MR images were analyzed by two radiologists

superior labral dimension was measured on coronal T1-weighted images, at the plane where long head of biceps tendon disappeared and labrum appeared the largest. Transverse and longitudinal dimensions were measured as base and height of the inverted triangular-shaped superior labrum and compared between patients who had SLAP on arthroscopy (SLAP group) vs. those who did not (non-SLAP group). Statistical analysis was done using unpaired t-test.

RESULTS 17 patients were excluded due to immeasurable image quality. Among 279 patients (283 shoulders), 122 patients (43.1%) had SLAP lesions, whereas 161 patients (56.9%) did not. The mean base/height of superior labrum in SLAP and non-SLAP patients measured on T1-weighted MR image were 8.8mm / 5.2 mm and 8.5mm / 4.9mm for radiologist 1, 8.2mm / 4.9mm and 8.1mm / 4.5mm for the session 1 of radiologist 2, 8.0mm / 4.8mm and 7.6mm / 4.3mm for the session 2 of radiologist 2. In the SLAP group, the mean labral height tended to be larger than that of non-SLAP group with statistically significant difference.

CONCLUSION In SLAP patients, the height of the superior glenoid labrum on oblique coronal image of MR arthrography was significantly larger than that of non-SLAP patients, and thus larger superior labral dimension could be predisposing factor of SLAP.