Conor Patrick Shortt MBBCh, Presenter: Nothing to Disclose

William B. Morrison MD, Abstract Co-Author: Medical Advisory Board, ONI Medical Systems, Inc

Adam C. Zoga MD, Abstract Co-Author: Speakers Bureau, Bayer AG

Angela Gessner Gopez MD, Abstract Co-Author: Nothing to Disclose

Javad Parvizi MD, Abstract Co-Author: Nothing to Disclose

ABER (abduction and external rotation) of the shoulder puts traction on the labral-capsular complex and can make labral tears more conspicuous. We propose to utilize a similar technique in the hip and assess its efficacy in diagnosing labral tears.

Eighty-three patients [47 males, 36 females, mean age 35 years (range 15-76)] underwent 87 hip MR arthrograms for suspected labral tear. Direct MR arthrography of the hip was performed at 1.5T post intra-articular dilute gadolinium contrast injection. First, each patient was imaged with the leg in the neutral position using a standard protocol. Next, the affected leg was abducted and externally rotated. In this position a repeat coronal T1W fat suppressed sequence was acquired. Images were reviewed retrospectively by 3 musculoskeletal radiologists in consensus for confidence level (1-5) of visualization of labral tear with and without FABER positioning. Secondary signs were also recorded including: paralabral cyst, cartilage loss, subchondral edema/cyst, bump at femoral head/neck junction and alpha angle. Tear location and optimal plane of visualization was also recorded. Correlation was made with surgical findings where available.

All patients tolerated MRI in the FABER position. Compared to images acquired in a neutral position, FABER images identified new findings in 18/87 (18%) of cases including 5 additional anterosuperior labral tears. Confidence level for labral tear diagnosis was increased in an additional 16/87(18%). In 27/36 (75%), FABER improved visualization of femoral neck bumps. Labral tear was significantly associated with increasing age, cartilage loss, bump formation and increased alpha angle. Of 15 cases with surgical correlation, MR arthrography correctly diagnosed labral tear in 13 (87%).

Direct MR arthrography of the hip performed in the FABER position improves visualization of labral tears and femoral neck bumps.

Shortt, C, Morrison, W, Zoga, A, Gopez, A, Parvizi, J, Use of Femoral Abduction External Rotation (FABER) Positioning for the Diagnosis of Acetabular Labral Tear during MR Arthrography.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6011142.html