Perthes Lesion – Anterior Labral Separation

Horng

Clinical History:
26 year old man who presents clinically following an anterior inferior dislocation of the left shoulder, with subsequent ventral instability

Diagnosis:
Perthes lesion (a variant of the Bankart lesion)

MR Technique:
MR images were acquired on a 1.5 T 8 channel MR unit (Magnetom Sonata, Siemens Medical Solutions, Erlangen, Germany) using (A) a proton density sequence with fat saturation (PD fs) and (B) a dual-echo steady state sequence (DESS). Sequence details are: PD fs: TR/TE 4150/27, 120 Hz/Px bandwidth, 200×200 mm2 field of view, 256×512 matrix, 0.8×0.4×3 mm3 spatial resolution, 2:33min acquisition time and DESS: TR/TE 21.8/5.7, 130Hz/Px bandwidth, 200x200mm2 field of view, 512×512 matrix, 0.4×0.4×2 mm3 spatial resolution, 4:38min acquisition time.

Imaging Findings:
Avulsion of the anterior-inferior labrum is demonstrated, with the labrum also shifted slightly medially. In distinction to the ALPSA (Anterior Labrum Periosteal Sleeve Avulsion) lesion, there is no dislocation of the medial labrum. Thus detection by MRI or MR Arthrography can be difficult. The sensitivity of the exam can be increased by using the ABER position (abduction, external rotation). In this position stress is placed on the anterior inferior labrum and the lesion may thus become more evident.