Florian Schmaranzer, Presenter: Nothing to Disclose

Michael Kogler MD, Abstract Co-Author: Nothing to Disclose

Markus Reichkendler, Abstract Co-Author: Nothing to Disclose

Ehrenfried Schmaranzer, Abstract Co-Author: Nothing to Disclose

Though direct MR arthrography (MRA) improved assessment of labral defects, tight anatomy of the hip restricts the visualization of labrum lesions in some cases. Therefore application of traction during MR imaging has been proposed to overcome femoroacetabular coaptation. It was aimed to assess the diagnostic performance of MRA of the hip under axial leg traction in the detection and grading of labrum lesions in patients with femoroacetabular impingement (FAI) and arthroscopy as reference.

Method and Materials: Over a period of 5 months, 53 symptomatic patients underwent preoperative MRA of the hip according to the institutional routine protocol on a 1.5 T unit and hip arthroscopy at our institution. The protocol included: coronal, sagittal, axial planes with traction and a coronal plane without traction and an intra articular injected volume of up to 27 ml. A dedicated traction device was used with weight load ranging from 15-23 kg according to patients constitution. After exclusion of 15 hips (1 LCE < 25°, 4 Tönnis 3, 3 previous surgery, 7 delay >6 months), 38 hips/patients (mean age; 34a, 14 cam-, 4 pincer-, 20 mixed-type FAI) remained in the study cohort. On coronal MR arthrograms obtained ± traction it was evaluated whether the chondro-labral interface could be differentiated. Lesions were graded as labral-chondral separations, partial/complete tears, flap tears and complex tears. Sensitivity, specifity and agreement within one grade of traction MRA in detection of labrum lesions was calculated with arthroscopy as reference.

With, without traction the chondro-labral interface could be differentiated in 37 (P =97%) respectively 10 hips (P =26%). 1/2 (P = 50%) intact labra, 2/5 (P = 40%) labral-chondral separations, 16/18 (P = 89%) partial tears, 2/2 (P = 100%) complete tears, 2/2 (P = 100%) flap tears and 9/9 (P = 100%) complex tears were correctly identified. Sensitivity, specifity, agreement within one grade was 97%, 50%, 84% respectively.

Traction MRA enabled delineation of the chondro-labral interface and was highly accurate in detection and grading of labrum lesions. Future trials should assess a potential benefit of traction MRA over conventional MRA.

The labrum ensures the dynamic stability of the hip joint. Traction MRA showed encouraging results in detection and grading of these lesions which should facilitate targeted therapy planning.

Schmaranzer, F, Kogler, M, Reichkendler, M, Schmaranzer, E, Diagnostic Performance of MR Arthrography of the Hip under Axial Leg Traction in the Detection and Grading of Labrum Lesions in FAI Patients: Preliminary Results.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14006696.html