The Limited Reliability of Physical Examination and Imaging for Diagnosis of Iliopsoas Tendinitis

Purpose: To determine if any association exists between physical examination, imaging findings [ultrasound (US) and magnetic resonance imaging (MRI)], and iliopsoas tendinitis (IPT) to characterize the reliability of these diagnostic modalities. Methods: Patients who had undergone US-guided iliopsoas tendon sheath injection (of lidocaine and a corticosteroid agent) as well as MRI performed within 1 year of injection from 2014 to 2019 were retrospectively reviewed. Demographic data, response to physical exam maneuvers, and response to injection were queried from patient records. US and MRI were reviewed by 2 independent musculoskeletal-trained radiologists. Response to injection was considered positive if the patient improved by >2 points on a 0- to 10-point VAS score. Chi-squared and Fisher exact testing were used to assess for any associations. Sensitivities, specificities, positive predictive values, and negative predictive values were calculated. Results: Sixty-three patients, age 52.3 ? 17.3 years (mean ? standard deviation), body mass index 27.4 ? 4.3 kg/m2, and follow-up 33.6 ? 20.6 months, met inclusion criteria. No physical exam maneuvers, sonographic features, or MRI findings were significantly associated with response to iliopsoas tendon injection (P > .05). Groin pain had a sensitivity of 100% but a specificity of 7%. Snapping hip had a specificity of 82% but a sensitivity of 24%. Pain with resisted straight leg raise (SLR) (sensitivity 62%, specificity 25%) and weakness with resisted SLR (sensitivity 15%, specificity 71%) both were nonreliable. Sonographic bursal distension and tendinosis had low sensitivities (67% and 63%, respectively) and specificities (35% and 32%). Bursal distension on MRI had sensitivity and specificity of 64% and 45%, respectively. Tendon thickening had sensitivity and specificity of 55% and 60%, respectively, and heterogeneity had sensitivity and specificity of 52% and 65%. Conclusion: Neither physical examination nor US or MRI findings were associated with a positive response to peritendinous iliopsoas corticosteroid injections in patients with suspected IPT. Level of Evidence: III, retrospective comparative trial limited by lack of a reference standard for iliopsoas tendonitis diagnosis.