Ueli Studler, Presenter: Nothing to Disclose

Fabian Kalberer MD, Abstract Co-Author: Nothing to Disclose

Michael Leunig, Abstract Co-Author: Nothing to Disclose

Marco Zanetti MD, Abstract Co-Author: Nothing to Disclose

Juerg Hodler MD, Abstract Co-Author: Research Consultant, Smith & Nephew plc Research Consultant, Bayer AG

Claudio Dora, Abstract Co-Author: Nothing to Disclose

Christian W.A. Pfirrmann MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To retrospectively evaluate the imaging characteristics of surgically proven sublabral recesses and labral tears in the anterior portion of the acetabulum on MR arthrography and to determine whether the characteristics of recesses were different from those of tears.

The study included 57 consecutive patients (36 women [mean age 37 years], 21 men [mean age 32 years]) who all had both MR arthrography and surgery or arthroscopy. The presence and location of anterior recess or labral tear was noted during hip arthroscopy or open surgery. On MR images, the presence and location of sublabral contrast interposition were recorded on a clock face. The depth, shape and extension into the labral substance of contrast interpositions were described. Abnormal labral signal intensity, acetabular cartilage lesions, osseous abnormalities and perilabral cysts adjacent to sublabral contrast interposition were noted. MR imaging findings were compared with the surgical findings which served as the reference standard.

Surgical procedures revealed 10/57 (18%) recesses and 44/57 (77%) tears. The location of recesses/tears were 7/0 in the 8-o’clock position, 2/2 in the 9-o’clock position, 1/22 in the 10- and 0/20 in the 11-o’clock position. None of the recesses extended through the full thickness of the labral base, whereas 49% of tears extended along the entire labral base. The shape of sublabral contrast interposition was linear in 83%/49% (recess/tear), gaping in 17%/16% and complex in 0%/35%. None of the recesses extended into the substance of the labrum, while 51% of tears did. Recesses were not associated with abnormal signal intensity of the labrum, cartilage lesions, osseous abnormalities, or perilabral cysts. Tears were associated with abnormal signal of the labrum in 74%, with cartilage damage in 54%, osseous abnormalities in 26%, and with perilabral cysts in 19%.

Sublabral recesses occur as a normal variant in the anteroinferior part of the acetabulum. The location in the 8-o’clock position, the linear shape of contrast interposition, partial separation of the labrum and the absence of perilabral abnormalities are characteristics of a recess on MR arthrography.

Sublabral recesses are quite common (18%) normal variants in the anteroinferior portion of the acetabulum and should be distinguished from labral tears to prevent unnecessary surgery.

Studler, U, Kalberer, F, Leunig, M, Zanetti, M, Hodler, J, Dora, C, Pfirrmann, C, et al, , How to Differentiate between an Anterior Sublabral Recess as Normal Variant and a Labral Tear at MR Arthrography of the Hip.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6016869.html