eMedicine Specialties > Radiology > Pediatrics
Slipped Capital Femoral Epiphysis
Updated: Mar 18, 2008
Introduction
Background
Slipped capital femoral epiphysis (SCFE) is the most common hip abnormality presenting in adolescence and is a primary cause of early osteoarthritis. Unfortunately, SCFE frequently is misdiagnosed, and it has symptoms that can be misleading.1 Early treatment leads to better outcome but is confounded by frequent delays in diagnosis.2
Pathophysiology
SCFE is a Salter-Harris type 1 fracture through the proximal femoral physis. Stress around the hip causes a shear force to be applied at the growth plate. Certainly, trauma has a role in the manifestation of the fracture, but an intrinsic weakness in the physeal cartilage also is present. The almost exclusive incidence of SCFE during the adolescent growth spurt indicates a hormonal role. Obesity is another key predisposing factor in the development of SCFE.3
The fracture occurs at the hypertrophic zone of the physeal cartilage. Stress on the hip causes the epiphysis to move posteriorly and medially. By convention, position and alignment in SCFE is described by referring to the relationship of the proximal fragment (capital femoral epiphysis) to the normal distal fragment (femoral neck). Because the physis has yet to close, the blood supply to the epiphysis still should be derived from the femoral neck; however, this late in childhood, the supply is tenuous and frequently lost after the fracture occurs. Manipulation of the fracture frequently results in osteonecrosis and chondrolysis because of the tenuous nature of the blood supply.4,5,6
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Fracture, Hip
Femoral Neck Fracture
Salter-Harris Fractures
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Frequency
United States
The incidence is 1 case per 100,000 people. SCFE occurs most frequently in adolescents, with a slightly greater incidence in males than in females. SCFE typically occurs just after the onset of puberty, frequently in overweight and slightly skeletally immature boys. African American children are affected slightly more commonly than are others. Additional underlying risks include malnutrition, endocrine abnormalities, and prior developmental dysplasia of the hip. Chemotherapy, irradiation, and renal failure also predispose individuals to SCFE. Slippage is bilateral in 20-37% and synchronous in 9-18% of patients, and they almost always appear in the first 2 years after initial presentation.
Mortality/Morbidity
SCFE is a fracture through the physis. Unlike typical Salter-Harris type I fractures, SCFE has a high propensity for morbidity. The nutrient vessels of the epiphysis are beginning to penetrate the physis as it closes, and when the physis is disrupted, avascular necrosis of the head may result, particularly if the head is manipulated. The tilted epiphysis is mechanically unfavorable and increases weight bearing on the lateral edge.
- Severe degrees of varus may limit abduction and lead to further slippage and eventual acetabular arthrosis. In some series, 40% chondrolysis has been reported, which occurs more frequently in African Americans and in patients whose hips have been manipulated.
- Premature closure of the physis may lead to limb shortening.
Race
African American children are affected slightly more often than others.
Sex
The incidence is slightly greater in boys than in girls.
Age
SCFE typically occurs just after the onset of puberty, frequently in overweight and slightly skeletally immature boys. It is often seen in children in whom puberty is delayed. Girls who present are slightly younger than boys who present, and the condition is never seen in children who have a closed growth plate. The inclination of the growth plate from the horizontal toward the vertical also leads to an increase in vertical shear forces, promoting slippage.
Anatomy
SCFE is a disease exclusively of the proximal femur. The fracture occurs through the hypertrophic zone of physeal cartilage. Abductors around the hip tend to pull the femur laterally and anteriorly. The epiphysis remains in place, and when the femur moves back to neutral, the epiphysis appears to have slipped medially and posteriorly.
Presentation
Clinical presentation often is misleading, with only 50% of patients presenting with hip pain and 25% presenting with knee pain. Diagnostic errors are typical, and 26% of patients experience delay in treatment. The most common misdiagnoses include muscle strain, Osgood-Schlatter disease, and flat feet. Moderate-to-severe slips are present 50% of the time; the outcome of SCFE is related directly to the severity of the slip at treatment.
The treatment of SCFE entails stabilizing the hip. Pins, screws, and wires have been used to cross the physis and fix the epiphysis.7 The goal is to avoid further damage to the penetrating vessels by stabilizing the fracture. The physis always closes after treatment. Most patients will not lose much growth potential since this physis would soon have closed. Most frequently, the bones are left with the tilt seen at presentation, and manipulation is attempted only in patients in whom the tilt impedes function. Manipulation almost always results in avascular necrosis. Chondrolysis also occurs frequently, more often in African-American children. Some complications appear to arise from synovitis, which may accompany the slip. These complications may result in early development of osteoarthritis of the hip.8
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Osteoarthritis
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Preferred Examination
Diagnosis is made using anteroposterior (AP) pelvis and lateral frog-leg radiographs.9
CT is a sensitive method of measuring the degree of tilt and detecting early disease, but it is rarely needed. CT may be performed with low doses, and reconstructions may allow viewing of the relationship of the femoral head to the metaphysis in three planes.
MRI depicts the slippage earliest, and MRI can demonstrate early marrow edema and slippage. MRI may be helpful in follow-up studies of the contralateral hip.10
Limitations of Techniques
Radiographs are the easiest images to obtain and provide an excellent screening examination for hip pain in any patient. In patients with SCFE, advanced stages of the disease are easy to identify; however, subtle changes early in the course are more difficult to detect. Before the femoral epiphysis actually has become displaced, only a slight widening of the affected physis may be evident. A metaphyseal blanch is an increase in density in the proximal metaphysis. It is presumed that metaphyseal blanch represents an attempt at healing that occurs before there is visible displacement of the epiphysis. MRI or CT may be able to detect SCFE in early cases.
Differential Diagnoses
Other Problems to Be Considered
Flat feet
Muscle strain
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References
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Murray AW, Wilson NI. Changing incidence of slipped capital femoral epiphysis: A RELATIONSHIP WITH OBESITY?. J Bone Joint Surg Br. Jan 2008;90(1):92-4. [Medline].
Yildirim Y, Bautista S, Davidson RS. Chondrolysis, osteonecrosis, and slip severity in patients with subsequent contralateral slipped capital femoral epiphysis. J Bone Joint Surg Am. Mar 2008;90(3):485-92. [Medline].
Lim YJ, Lam KS, Lim KB, Mahadev A, Lee EH. Management outcome and the role of manipulation in slipped capital femoral epiphysis. J Orthop Surg (Hong Kong). Dec 2007;15(3):334-8. [Medline].
Odgers CJ, Dabney K. Bilateral Slipped Capital Femoral Epiphysis. 1996. Available at: http://gait.aidi.udel.edu/res695/homepage/pd_ortho/educate/clincase/scfe.htm. Accessed March 13, 2008. [Full Text].
Miyanji F, Mahar A, Oka R, Pring M, Wenger D. Biomechanical comparison of fully and partially threaded screws for fixation of slipped capital femoral epiphysis. J Pediatr Orthop. Jan-Feb 2008;28(1):49-52. [Medline].
Yamamoto LG. Thigh and Knee Pain in an Obese 10-Year Old. Radiology Cases in Pediatric Emergency Medicine. 1995. Available at: http://www2.hawaii.edu/medicine/pediatrics/pemxray/v2c10.html. Accessed March 13, 2008. [Full Text].
Keiser V, Berlin S, Myers M, et al. Slipped Capital Femoral Epiphysis. Pediatric Imaging Teaching Files. Available at: http://www.uhrad.com/pedsarc/peds049.htm. Accessed March 13, 2008. [Full Text].
Resnick D. Diagnosis of Bone and Joint Disorders. 3rd ed. Philadelphia: WB Saunders Co;1995.
Gekeler J. Radiology of adolescent slipped capital femoral epiphysis: measurement of epiphyseal angles and diagnosis. Oper Orthop Traumatol. Oct 2007;19(4):329-44. [Medline].
Further Reading
Keywords
SCFE, hip abnormality, early osteoarthritis, proximal femoral physis, Salter-Harris type 1 fracture, hip pain
