Adam C. Zoga MD, Presenter: Nothing to Disclose

George Paul Hobbs MD, Abstract Co-Author: Nothing to Disclose

Andrew S. Chi MD, MS, Abstract Co-Author: Nothing to Disclose

Suzanne Sundborg Long MD, Abstract Co-Author: Nothing to Disclose

William Clark Meyers MD, Abstract Co-Author: Nothing to Disclose

William B. Morrison MD, Abstract Co-Author: Consultant, General Electric Company Consultant, AprioMed AB Patent agreement, AprioMed AB

We sought to establish the incidence of unilateral or asymmetric psoas muscle atrophy in subject group with groin pain and a history of ipsilateral hip or lower abdominal surgery, and then correlate with the prevalence of psoas atrophy in a population without prior surgery.

A database of patients with pelvic MR for hip/groin pain was queried for a history of prior hip or abdominal surgery, generating 109 subjects; demographics, surgical history, and pain situs were recorded. 2 MSK radiologists independently reviewed MR exams retrospectively for the presence and degree of psoas muscle atrophy (mild = intramuscular signal abnormality, moderate = <50% volume loss, severe = >50% loss), atrophy within other core muscles, postsurgical lesions and native muscle, tendon or intrinsic hip injuries. A control group of 180 subjects with MR for groin pain but no history of regional surgery was reviewed for asymmetric psoas muscle atrophy. Potential causes of this phenomenon were then explored.

Asymmetric psoas atrophy was present in 24/109(22%) study subjects with reader consensus but only 5/180(2.7%) control subjects (p<0.001). 21/109 study subjects (19.3%) were graded as moderate or severe in consensus compared with 3/180(1.7%) in the control group (p<0.001).  The mean interval between surgery and MRI in study subjects with atrophy was 18.9 months. The majority (88%) of study subjects with psoas atrophy had prior hip arthroscopy, while 3 had hip arthroplasty (2 THR, 1 resurfacing).  33% had at least two hip arthroscopies and 1 had a prior psoas release. 61% of the arthroscopy subjects had a femoral osteotomy. Other surgeries in the psoas atrophy group included spigelian repair(1), inguinal herniorrhaphy(3), caesarian section(1) and pelvic floor (pubalgia) repair(4). 9 subjects with postoperative psoas atrophy had a preoperative MR pelvis, and all (9/9) had normal and symmetric psoas musculature on the preoperative MR.

We have documented a significant incidence of asymmetric psoas muscle atrophy at MR patients with hip/groin pain after ipsilateral hip or abdominal surgery. The majority of these subjects had hip arthroscopy and preoperative MRs showed normal psoas bulk when available.

The cause and significance of postoperative psoas atrophy warrants further investigation. Potential contributors include traction during arthroscopy, surgical exposure and perioperative trauma.

Zoga, A, Hobbs, G, Chi, A, Long, S, Meyers, W, Morrison, W, Psoas Muscle Atrophy in Patients with Ipsilateral Groin Pain: Is there an Association with Prior Hip Surgery and Why?.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13021138.html