Christian W. A. Pfirrmann MD, Presenter: Nothing to Disclose

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

Claudio Dora MD, Abstract Co-Author: Nothing to Disclose

Juerg Hodler MD, Abstract Co-Author: Nothing to Disclose

To evaluate magnetic resonance (MR) imaging findings of abductor tendons and muscles in asymptomatic and symptomatic patients after total hip arthroplasty (THA) using a lateral transgluteal approach.

Triplanar MR images of the greater trochanter of 25 asymptomatic patients (14 men, mean age 60.4 years, 11 women, mean age 60.2) after THA and 49 patients with trochanteric pain after THA (19 men, mean age 62.7 years, 20 women, mean age 64.3) were independently analyzed by two blinded musculoskeletal radiologists. Tendon defects, tendon quality, muscle quality and bursal fluid collections were assessed. In 14 symptomatic patients MR imaging was correlated to surgical findings.

Tendon defects were rare in asymptomatic patients and significantly more frequent in symptomatic patients (gluteus minimus defects in asymptomatic 8% vs. 56% in symptomatic patients, p<0.001; lateral gluteus medius tendon defects 16% vs 62%, p<0.001; posterior gluteus medius tendon defects 0% vs18%, p<0.025). Signal changes within tendons were very frequent in both groups except for the posterior gluteus medius tendon which demonstrated this finding more frequently in symptomatic patients (20% vs 59%, p=0.002). Changes in tendon diameter are very frequent in both groups but significantly (p=0.001-009) more frequent in symptomatic patients for all tendon parts. Fatty atrophy was evident in the anterior two thirds of the gluteus minimus muscle in both asymptomatic and symptomatic patients without significant differences. Fatty atrophy of the gluteus medius muscle was only present in symptomatic patients. Bursal fluid collections were more frequent in asymptomatic (32%) compared to symptomatic patients (62%, p=0.021). The MR diagnosis was confirmed in all 14 patients undergoing revision surgery.

Many MR findings such as signal and diameter changes of the abductor tendons, fatty atrophy of the anterior gluteus minimus muscle and bursal fluid collections are frequently found in asymptomatic patients after THA. However, defects of the abductor tendons and fatty atrophy of the gluteus medius and the posterior part of the gluteus minimus muscle are rare in asymptomatic patients.

Pfirrmann, C, Zanetti, M, Dora, C, Hodler, J, MR Imaging of the Abductor Tendons and Muscles after Total Hip Arthroplasty in Asymptomatic and Symptomatic Patients.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4412837.html