Antero-medial Thigh Pain: An Enigmatic Cause Of Referred Pain In A Pediatric Patient.

HISTORY: A 9 year old female presents with left thigh pain that began one month prior after she fell while running and landing on her lateral left thigh. Pain has worsened, being unable to run and has antalgic limping. Patient localizes pain on the anterior and medial thigh. Pain has not improved with rest and over the counter analgesia. PHYSICAL EXAMINATION: BMI: 21.96 kg/m2. Antalgic gait. Tenderness to palpation on anteromedial left thigh. Positive FADIR with negative log roll and FABER. Straight leg raise neg. Slump test was equivocal. Left gastrocnemius equinus significantly worse than the right. DIFFERENTIAL DIAGNOSIS:Avascular necrosis of the femoral neck Femoral neck stress fracture SCFE Septic or reactive arthritis Spinal cord abnormality TEST AND RESULTS:Pelvis, hips, femur and lumbar xray: No evidence of fracture, subluxation or soft tissue abnormality. Incidental bone island in the right ischium. MRI hip without contrast: There is severe bone marrow edema in the femoral epiphysis with cartilage loss and possible flattening of the articular surface. There is bone marrow edema also noted in the acetabulum. There is no double line sign to suggest osteonecrosis. There is minimal joint effusion with no significant periarticular soft tissue swelling to suggest infectious process (image below). MRI of the lumbar spine without contrast: Small central disc protrusion L5 S1. Otherwise unremarkable exam. Inflammatory markers (WBC, ESR, CRP): within normal limits. FINAL WORKING DIAGNOSIS: Idiopathic Transitional Osteoporosis of the Hip. TREATMENT AND OUTCOMES: Conservative treatment with oral analgesics and non-weight bearing of left lower extremity. Symptoms improved initially with non weight bearing, but pain returned after increasing activity level against medical advice. Continuing to follow with ortho to track progress.