Ortho Hors D'oeuvres (Answer):
To review, this is a 10 year-old boy brought in to the emergency department for one day of atraumatic left hip pain.
Questions and Answers:
1) what is the key finding on x-ray?
In this film, there is posterior and inferior slippage of the proximal femoral epiphysis on the metaphysis (femoral neck), which occurs through the epiphyseal plate (growthplate).This orthopedic injury is commonly known as slipped capital femoral epiphysis (SCFE).
SCFE are categorized radiographically by degree of slippage using Klein’s line, which is a line drawn along the superior border of the femoral neck. This line should intersect with the femoral head in a normal child and the percentage of uncovered femoral neck corresponds with the severity of the SCFE.
2) What are the common risk factors and exam findings?
Common risk factors include male gender and adolescent age. Average age is 13.5 years for boys, 12.0 for girls. Obesity is also a risk factor, although only 63% of patients will have a weight in the 90th percentile or higher. Exam findings include a limp and inability to bear weight. Pain from SCFE injury is often poorly localized pain to the hip, groin, thigh, or knee. This injury may occur bilaterally in 18% to 50% of patients. Limitations in internal hip rotation and increased passive external hip rotation on knee flexion, as seen in this patient, are very specific.
3) What is the management?
In the emergency department, the patient should be made non-weightbearing (crutches or wheelchair). If the patient can bear weight on the affected extremity even partially, the fracture is considered a stable fracture and require as little as a single screw for fixation.
If the patient is unable to even partially bear weight the fracture is considered unstable and will require operative fixation, with possible reduction or traction prior to open reduction internal fixation.
SCFEs have a high rate of osteonecrosis so need to be managed emergently and require immediate orthopedics consultation.
Loder RT, Richards BS, Shapiro PS, Reznick LR, Aronson DD. “Acute slipped capiral femoral epiphysis: the importance of physeal stability. J Bone Joint Surg Am. 1993;75(8):1134.
Peck D. "Slipped Capital Femoral Epiphysis: Diagnosis and Management." American Family Physician 82.3 (2010): 258-62.
Thanks to Eric Silman for the plain film image!