Acute hip pseudoparalysis with calcific tendinitis at the insertion of the psoas muscle. Case report and first description of an atypical location

Calcific tendinitis is a common and widespread disease. It is most common in the rotator cuff especially in the supraspinatus tendon. In some cases it may also involve other locations such as the hips, particularly at the trochanter minor. In particular calcific tendinitis of the iliopsoas muscle tendon has not yet been described. Because of uncharacteristic symptoms and ambiguous diagnostic imaging the differentiation between traumatic, infectious and neoplastic genesis is often difficult. Because of artefacts the typical calcareous spots near the insertions are often underdiagnosed in conventional diagnostic x-ray images. In this case report the differentiation from an infection of the hip was only possible with positron emission tomography computed tomography (PET-CT) imaging and negative microbiological testing of an aspirate. There are various therapy options, such as systemic and local medication, extracorporeal shock wave therapy up to surgery. However, calcific tendinitis is a self-limiting tendinopathy that can be treated with conservative therapy to complete remission in most cases.