The Case Files

Abstract

An 11-year-old boy was brought into the ED by wheelchair complaining of left hip pain after slipping and falling on the floor at home just prior to arrival. He was not able to get up. The patient also reported that he had fallen two weeks earlier while running, and had had ongoing left hip discomfort since then. He denied any other injuries or complaints, and had no significant past medical history. He de-nied prior surgeries, allergies, and medications. His temperature was 98.4°F, pulse 103 bpm, blood pressure 128/71 mm Hg, respiratory rate of 20 breaths per minute with O2 saturation of 99% on room air. He reported his pain as 10/10. This overweight boy was lying uncomfortably on the stretcher, moaning in pain. His pupils were equally round and reactive to light. He had a normal pharynx with no erythema or tonsil-lar hypertrophy; his neck was supple and nontender without lymphadenopathy. His heart rate was regular with no murmurs, rubs, or gallops, and his lungs were clear to auscultation with no wheezes, rhonchi, or rales. His abdomen was soft with normal bowel sounds, nondistended and nontender. He was lying with his left leg externally rotated, and he had left hip tenderness and limited range of motion due to pain. He was unable to bear weight but had good distal pulses, capillary refill <2 seconds, and no clubbing, cyanosis, or edema. He was awake, alert, and oriented, his deep tendon reflexes were intact, and he had normal strength and normal sensation. An emergency bedside ultrasound was performed with the patient in the supine position. A high-frequency linear probe was placed parallel to the femoral neck and perpendicular to the groin line. Ultrasound of the right hip appeared normal. (Fig. 1.) The ultrasound of the left hip revealed a physeal step-off with posterior displacement of the proximal portion. (Fig. 2.) A plain AP radiograph of hips and pelvis was performed to confirm the diagnosis, and showed moderate slippage of the left capital femoral epiphysis. (Fig. 3.)Figure 1: Normal right hip: epiphysis (star), epiphyseal plate (arrow), metaphysis (triangle).Figure 2: Anterior ultrasonogram of left hip: a broadened epiphyseal plate with physeal step (arrow), epiphysis (star), metaphysis (triangle).Figure 3: AP pelvis with hips showing moderate slippage of left capital femoral epiphysis.The patient underwent left hip in situ pinning of his slipped capital femoral epiphysis that day before staying the night in the pediatric unit. Day one post-surgery, he received physical ther-apy and was discharged with outpatient follow-up with his orthopedist. The incidence of slipped capital femoral epiphysis (SCFE) in the United States is 10 cases per 100,000 children. The left hip is more commonly affected than the right, and it is twice as com-mon among boys as girls, although incidence is changing as more girls are participating in sports. (Hosp Med 1999; 60[11]:788.) The disorder is mainly characterized by hip pain, inability to bear weight or limp, and decreased range of motion. (Pediatr Ann 2006;35[2]:102.) Its clinical manifestation is caused by the instability of the proximal femoral growth plate. Swift diagnosis and definitive treatment are critical in preventing complications such as avascular necrosis, chondrolysis, and degenerative arthritis. (Curr Opin Pediatr 1998;11[1]:80.) The diagnosis on plain radiography is made by visualizing a displaced femoral epiphysis and a fracture through the physis. Radiographic imaging can prove inaccurate because of projectional errors from the difficulty in positioning painful affected hips. (J Bone Joint Surg Br 1991;73[6]:884.) Plain radiographs have traditionally been the gold standard for diagnosis, but this case and multiple other studies demonstrate that ultrasound is a safe and ac-curate modality for the prompt clinical diagnosis of SCFE.ImageNo step is seen between the metaphysic and epiphysis in a normal hip. A physeal slip and broadened epiphyseal plate can be visualized in a hip with SCFE using ultrasound. Some studies even suggest that measuring the anterior physeal slip can be used to grade the severity and to assess even minimal slippage. (Acta Orthop Scand 1992;63[6]:653; Radiol Med 1998;95[1–2]:16.) Ultrasound is increasingly being used as the imaging modality of choice in the diagnosis of SCFE because of its sensitivity, repeatability, and safety because it does not impart ionizing radiation to the patient. Studies suggest that a skilled ultrasonographer, such as a trained emergency physician, is able to diagnose SCFE reliably and efficiently using ultrasound. It is essential that emergency physicians remain aware of possible alternative and supplemental imaging modalities to ensure prompt patient diagnosis and disposition for SCFE.