Iliacus muscle injury in a young athlete with hip dysplasia

Traumatic iliacus muscle injury has been rarely reported in literature as its incidence is very low compared to other muscle injuries. It is usually caused by trauma or inadequate exercise involving the pelvic girdle. It can produce a hematoma with femoral nerve neuropathy. Spontaneous muscle hematomas occur in patients with coagulation disorders. Hip dysplasia is associated with muscle-tendon abnormalities: the reduced acetabular coverage of the femoral head leads to an increased mechanical load on the hip joint and the acting hip muscles. A 14-year-old girl presented to our emergency department complaining left groin pain after sport activity, after the usual warm up routine before an exhibi¬ tion of rhythmic gymnastics. At the clinical exam presented a complete hip range of motion with a positive F A D D I R sign and pain at the flexion of the hip and at the extension of the leg against resistance. The X-rays showed a bilateral mild hip dysplasia. The magnetic resonance imaging (MRI) scan showed an extensive iliacus muscle detachment from the proximal insertion at the iliac fossa with a hematoma lying between the iliacus and the ilium. After 3 months from the injury the patient was completely asymptomatic. A new MRI scan was performed: it showed an almost complete regression of the hematoma and the detachment of iliacus muscle. Groin pain in hip dysplasia frequently has a muscle-tendon-related cause, especially in case of trauma during sports activity, and one of the structures that is most frequently involved is the iliopsoas muscle. A positive clinical evaluation correlates with instrumental evidence (ultrasonography, MRI, computed tomography); in case of hematoma of the psoas muscle, coagulative disorders must be excluded. If there is no functional involvement of vascular and nervous structures adjacent to the hematoma, conservative treatment is recommended.