Olaf Magerkurth MD, Presenter: Nothing to Disclose

Jon A. Jacobson MD, Abstract Co-Author: Consultant, BioClinica, Inc Royalties, Reed Elsevier Grant, Harvest Technologies Corporation

Yoav Morag MD, Abstract Co-Author: Nothing to Disclose

Elaine M. Caoili MD, Abstract Co-Author: Nothing to Disclose

Jon Sekiya, Abstract Co-Author: Royalties, Orthodynamix, LLC Stockholder, Orthodynamix, LLC Consultant, Orthodynamix, LLC Royalties, Arthrex, Inc Consultant, Arthrex, Inc Royalties, Reed Elsevier

To retrospectively describe MRA findings associated with capsular laxity of the hip joint found at surgery.

IRB approval was obtained. Patients with MRA and surgically assessed presence or absence of laxity of the hip joint were included. Axial T1w Images were randomized and reviewed twice by 2 independent, blinded readers. The widths of the anterior joint space lateral to the zona orbicularis and of the posterior joint space were measured. The angle between femoral neck and ischium was measured to assess hip rotation. Volumes of contrast injected into the joint were obtained from MRA reports. Statistical differences between these two groups were calculated with a t-test. Inter- and intra-reader agreement as well as correlation of widths of joint spaces with angles and volume of contrast was evaluated with a Pearson test.

The study group consisted of 27 subjects (10 males, 17 females; age: 15–61) of which 17 were positive and 10 negative for hip laxity at surgery. The mean width of the anterior joint space was 6mm (range 3–10) in the laxity group and 4mm (range 2–5) in the group without laxity, which was significantly different (p<0.0001). The mean width of the posterior joint space was 6mm (range 4–11) in the laxity group and 5mm (range 3–8) in the group without laxity, which was significantly different (p=0.0029). There was no difference in mean femoral neck/ischium angles between the groups (p=0.3) or mean volume of contrast (12ml) (p=0.2). There was no correlation between the angle/volume to the widths of the joint spaces (r2:0.001-0.1). Inter- and intra-reader agreement was high (r2:0.78-0.9).

Distention of the anterior and posterior joint space was greater with hip laxity, independent of intra-articular contrast volume and hip rotation. Distention of the anterior joint space >5mm is suggestive for capsular laxity of the hip joint.

Repetitive injuries of the hip joint can cause painful atraumatic instability, which can be treated with arthroscopic capsulorraphy. We present MR arthrographic (MRA) findings that indicate hip laxity

Magerkurth, O, Jacobson, J, Morag, Y, Caoili, E, Sekiya, J, Capsular Laxity of the Hip: Findings at MR Arthrography.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034627.html