-To review the clinic symptoms and radiological features commonly associated to iliopsoas impingement, as a common complication in patients with THR (Total Hip Replacement) - To assess the clinical results of US-guided injection of corticosteroids in these patients, and their possible relation with iliopsoas changes and other possible pain causes detected in CT

Retrospective review of 41 consecutive patients treated by US-guided corticosteroid injections at our institution. Procedures performed from January 2014 to July 2017 were included. Clinical outcomes (complete pain resolution, partial pain resolution, no significant pain relief and therapeutical failure-need for a new surgical procedure) were obtained from radiologist follow-up visits 6 and 12 weeks after the procedures, and from medical records, with a follow-up of 9 to 51 months. The CT findings obtained were: Overhanging acetabular cup, fat infiltration and atrophy of psoas muscle, other...

Clinical improvement (partial or complete pain resolution) was obtained in 65,9% of patients (27 patients), of which complete resolution of pain was reached in 22% (9 patients) and partial resolution in 43,9% (18 patients) The percentage of patients not achieving pain relief was 34,1% (14 patients), of which therapeutical failure patients -whom needed a new surgical procedure- were 17,1% (7 patients) The 14 patients with other sources of pain detected on CT: heterotopic ossification (7 cases), screw malpositioning (3 cases), cement migration (1 case), prosthetic...

Corticosteroid US-guided injection led to clinical improvement in 65,9% of patients with clinically suspected iliopsoas impingement after total hip replacement. A low percentage of cases (17,1%) needed a new surgical procedure. Patients with other visible causes of pain in the CT got worse clinical results (statistically significant) Statistically significant differences were also found between genres, women getting better results. In this review, no statistically significant differences were found in clinical improvement depending on iliopsoas fat infiltration or atrophy, or overhanging of the acetabular cup.

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