Bano et al. Journal of Medical Case Reports 2010, 4:236 http://www.jmedicalcasereports.com/content/4/1/236 Page 2 of 4 Figure 1 MRI performed a few days after injury. (a) The transverse fat suppressed proton density turbo spin echo (TSE) and (b) the coronal short tau inversion recovery (STIR) images, show the hematoma formation in the quadratus femoris muscle (arrows) extending to the obturator internus muscle (open arrows). normal. Standard hip, lumbar spine and pelvis radio- graphs were unremarkable. The complete laboratory work-up did not reveal any indication for infection or coagulopathy. Based on the above, the initial clinical impression was piriformis syndrome. A new MRI exami- nation of our patient was requested for confirmation. This showed that the previous muscular strain showed only a minor degree of hematoma absorption compared to the previous study (Figure 2). Thus, hematoma for- mation was thought to be responsible for her persistent sciatica. A conservative approach, by means of strength- ening of our patient’s external rotators muscles, did not show any improvement for one month. The lack of obvious fluid effusion did not allow computed tomogra- phy (CT)-guided drainage. A surgical exploration of our patient was then performed through a posterolateral approach of the right hip. Intra-operatively, an atrophic quadratus femoris muscle was found, with complete detachment at the tendon-bone junction from the quad- rate tubercle of the femur (grade III strain) (Figure 3). An associated solid mass (5 cm × 2 cm × 3 cm), repre- senting chronic hematoma and fibrosis, was attached to and compressed the sciatic nerve. After decompressing the sciatic nerve from the fibrotic and granulation tissue, the newly formed mass was evacuated. The greater tro- chanteric bursa and contiguous structures were noted to be normal. The histological findings were compatible with degenerative muscular changes including fibrotic tissue, significant atrophy and fatty replacement (Figure 4). Post-operatively, management consisted of physical rehabilitation with emphasis on the strengthening of the external rotator muscles with pain-free isometric pro- gressive exercises. One month after surgery, our patient was free of symptoms and returned to work. At the one-year follow-up, she had no abnormal symptoms or signs. Discussion Post-traumatic pain located in the buttock area may develop following a pelvic or coccygeal fracture or a muscle strain, with hematoma resulting in sciatic nerve compression. A traumatic lumbar disc herniation may be found in patients with radicular pain. For a correct clinical evaluation it is essential to assess the osseous structures and the muscles around the hip joint. The quadratus femoris muscle is a flat quadrilateral muscle that arises from the upper external border of the ischial tuberosity and inserts at the quadrate tubercle of the femur [3]. It acts as a hip external rotator and assists adduction [3,4]. The quadratus femoris muscle is inner- vated by the quadratus femoris nerve which rises from the ventral roots of the L4, L5 and S1 nerves in 79.4% of patients [5]. In adults, the myotendinous junction is the most vulnerable location for injury [6,7]. The tendon insertion in the bone may also be affected. Only a few cases describing a quadratus femoris muscle injury have been reported in the literature. The incidence of the quadratus femoris muscle tear is unknown. O’Brien and Bui-Mansfield presented a review of seven cases [1]. In this study, this type of injury occurs predo- minantly in women (as in our case) with a female to male ratio of 6:1. The age of patients ranges from 17 to 43 years with an average age of 29.6 years. The symptoms were hip pain in three patients, groin pain in one patient and deep posterior thigh or gluteal pain in three patients. In none of the cases reported was there a correct clinical diagnosis of quadratus femoris muscle tear. Diagnosis was confused with a hamstring injury, snapping hip syn- drome or lumbar radiculopathy. The delay from time of injury to correct diagnosis varied from one day to five months [1]. In one case the injury was located at the ten- don insertion and in the rest at the musculotendinous part. All cases were evaluated by MRI examination.