[Congenital hypoplasia of the lower portion of the left psoas muscle].

We are presenting a case of a 58-year-old-male patient with a congenital hypoplasia of the lower portion of his left psoas muscle. This rare anomaly, which should be differentiated from other pathological conditions (destructive processes, tumors, metastases, inactivate atrophy), was discovered during the MRI examination of his lumbosacral (LS) spine which the patient underwent due to deterioration of chronic low back pain. His right psoas muscle was hypertrophic. CT examination of his abdomen has shown the identical finding. The MRI examination of his LS spine has shown the intensive and extensive degenerative changes. Besides the hypoplasia of the lower portion of his left psoas muscle, the radiological examinations of the LS spine (MRI) and abdomen (CT) have not shown any other congenital anomalies. Taking into consideration the patient history, the clinical finding, the results of the radiological and other examinations (EMNG) as well as the well known facts about psoas muscle anatomy and function (a stabilizer of the lumbar spine, pelvis and hip; the hip and trunk flexor; the lateral trunk flexor), in this case report, we analysed the clinical manifestations (lateral deviation of lumbar spine; pelvic asymmetry--elvic torsion; increased hip extension on the side of the hypoplastic psoas muscle) and also the late consequences of the unilateral hypoplasia of the psoas muscle (unilateral hypoplasia of the psoas muscle--the overloading of the LS spine and the other psoas muscle--the chronic low back pain--the compensatory hypertrophy of the other psoas muscle-->the intensive and extensive degenerative changes of the LS spine).