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

Abstract PURPOSE To determine if any association exists between physical examination and/or imaging findings [ultrasound (US) and magnetic resonance imaging (MRI)] and IPT in order 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 one year of injection between 2014-2019 were retrospectively reviewed. Demographic data, response to physical exam maneuvers, and response to injection were queried from patient records. US and MRIs were reviewed by 2 independent musculoskeletal-trained radiologists. Response to injection was considered positive if the patient improved by >2 points on a 0-10 VAS score. Chi-square and Fischer exact testing was utilized to assess for any associations. Sensitivities, specificities, positive predictive values, and negative predictive values were calculated. RESULTS Sixty-three patients, with mean age 52.3 years +/- 17.3, with average BMI 27.4 +/- 4.3, and average follow-up was 33.6 months +/- 20.6 met inclusion criteria. No physical exam maneuvers, sonographic features, or MRI findings were significantly associated with response to iliopsoas tendon injection (p>0.05). Groin pain had a sensitivity of 100%, though a specificity of 7%. Snapping hip had a specificity of 82%, though a sensitivity of 24%. Pain with resisted SLR (sensitivity 62%, specificity 25%), and weakness with resisted SLR (sensitivity 15%, specificity 71%) both were non-reliable. Sonographic bursal distension and tendinosis had low sensitivities (67% and 63%, respectively) and specificities (35% and 32%, respectively). Bursal distension on MRI had sensitivity and specificity of 64% and 45% respectively. Tendon thickening had sensitivity and specificity of 55% and 60%, respectively, while heterogeneity had sensitivity and specificity of 52% and 65%, respectively. CONCLUSION Neither physical examination, nor US, nor MRI findings were associated with a positive response to peritendinous iliopsoas corticosteroid injections in patients with suspected IPT.