eMedicine Specialties > Radiology > Pediatrics

Slipped Capital Femoral Epiphysis

Brent Adler, MD, Chief of Musculoskeletal Imaging, Department of Radiology, Children's Hospital

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 ]}

Related eMedicine topics:
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 ]}

Related eMedicine topics:
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

Radiography

Findings

Diagnosis is made using AP pelvis and lateral frog-leg radiographs. Abduction of the femur for the frog-leg view may result in increased slippage and should be performed with caution (see Images 1-6).

On AP radiographs, close attention should be paid to the physis. Early in SCFE, the physis may widen. Increased opacity in the metaphysis, described as blanching, may occur as an early healing response, and the epiphysis may appear smaller because it is tilted dorsally.

The lateral radiograph demonstrates slippage earliest because the slippage begins with posterior displacement and progresses with medial rotation.

The Southwick method can be used by creating an axis for the femoral neck and determining whether the epiphysis is tilted (see Image 4).

An additional method is to draw a line along the lateral aspect of the femoral neck on the AP view; this line, known as the line of Klein, should intersect a portion of the femoral head.^{[11 ]}

Degree of Confidence

Degree of confidence in radiographic findings of SCFE is high.

False Positives/Negatives

When the aforementioned constellation of findings is present, false-positive and false-negative findings do not occur.

Computed Tomography

Findings

CT is a sensitive method for measuring the degree of tilt and detecting disease, but it is rarely needed. Usually, CT is performed only at the request of the treating physician for documenting the severity of the tilt.

Magnetic Resonance Imaging

Findings

The earliest way to detect SCFE is by using MRI. With MRI, early marrow edema and slippage can be demonstrated. This is demonstrated with increased signal on T2-weighted and water-sensitive images. MRI can be considered in patients for whom the clinical suspicion of SCFE is high and in whom the radiographs appear normal. MRI can be considered for follow-up imaging of the contralateral hip.

False Positives/Negatives

Marrow edema is a nonspecific finding, and while it can indicate early bone changes in SCFE, it has numerous other causes, such as infection or even tumor. Those diagnoses are rarely considered with the proper clinical evaluation.

Ultrasonography

Findings

Ultrasonographic findings are rarely specific, and the sensitivity of sonography is unknown. Hip effusions of blood often have been reported and are suggestive of fracture.

Nuclear Imaging

Findings

The radionuclide bone scan is sometimes used during workup but prior to diagnosis. Accumulation of the bone scanning agents can be decreased after fixation and in patients with an acute slip and significant displacement. The decrease is usually limited to the epiphysis. The decreased accumulation is associated with increased incidence of chondrolysis.

Intervention

Patient Education: For excellent patient education resources, visit eMedicine's Foot, Ankle, Knee, and Hip Center and Sports Injury Center. Also, see eMedicine's patient education article Repetitive Motion Injuries.

Medicolegal Pitfalls

• The frequency of a missed diagnosis of SCFE is high.
• Often, children present with vague knee or hip complaints weeks prior to the occurrence of complete slippage.
• Because the clinical signs are not helpful, meticulous technique and evaluation of hip and pelvis images are important in the adolescent age group.

See also the Medscape topic Medical Malpractice and Legal Issues.

Multimedia

Media file 1: Slipped capital femoral epiphysis. A 13-year-old female adolescent with acute-onset right hip pain. She had presented to the emergency department 1 week prior with right knee pain. On this anteroposterior pelvic view, note the increased opacity of her right metaphysis and the subtle widening of the physis.

Media file 2: Slipped capital femoral epiphysis. A 13-year-old female adolescent with acute-onset right hip pain had presented to the emergency department 1 week prior with right knee pain (detailed view, same patient as in Image 1). The patient has blanching of the metaphysis and only subtle widening of the physis. The epiphysis is yet to be displaced.

Media file 3: Slipped capital femoral epiphysis. This child had undergone radiation treatment for a pelvic malignancy. On this anteroposterior hip image, the pathologic slippage is not subtle.

Media file 4: Slipped capital femoral epiphysis. Frog-leg pelvic image in a child with bilateral slipped capital femoral epiphysis. A line perpendicular to the epiphyseal axis and another along the axis of the femoral neck demonstrate the degree of tilt by using the Southwick method.

Media file 5: Slipped capital femoral epiphysis. Image in a 14-year-old male adolescent who came to the emergency department with complaints of thigh and knee pain. A relatively subtle medial slip is pictured here.

Media file 6: Slipped capital femoral epiphysis. Image of a 14-year-old male adolescent who came to the emergency department with complaints of thigh and knee pain (same patient as in Image 5). A more obvious posterior slip is noted on this frog-leg lateral view.

References

1. Ballas MT, Tytko J. Commonly Missed Orthopedic Problems page. American Academy of Family Physicians Web site. 1998. Available at: http://www.aafp.org/afp/980115ap/ballas.html. Accessed March 13, 2008. [Full Text].

2. Boles CA, el-Khoury GY. Slipped capital femoral epiphysis. Radiographics. Jul-Aug 1997;17(4):809-23. [Medline].

3. 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].

4. 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].

5. 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].

6. 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].

7. 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].

8. 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].

9. 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].

10. Resnick D. Diagnosis of Bone and Joint Disorders. 3rd ed. Philadelphia: WB Saunders Co;1995.

11. 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].

Keywords

SCFE, hip abnormality, early osteoarthritis, proximal femoral physis, Salter-Harris type 1 fracture, hip pain

Contributor Information and Disclosures

Author

Brent Adler, MD, Chief of Musculoskeletal Imaging, Department of Radiology, Children's Hospital
Brent Adler, MD is a member of the following medical societies: American College of Radiology, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.

Medical Editor

Beverly P Wood, MD, MS, PhD, Professor, Departments of Radiology and Pediatrics, Division of Medical Education, Keck School of Medicine, University of Southern California
Beverly P Wood, MD, MS, PhD is a member of the following medical societies: American Academy of Pediatrics, American Association for Women Radiologists, American College of Radiology, American Institute of Ultrasound in Medicine, American Medical Association, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, and Society for Pediatric Radiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

Marta Hernanz-Schulman, MD, FAAP, Professor, Radiology, Radiological Sciences, and Pediatrics, Director, Department of Pediatric Radiology, Radiologist-in-Chief, Director, Department of Diagnostic Imaging, Vanderbilt University Medical Center, Vanderbilt Children's Hospital
Marta Hernanz-Schulman, MD, FAAP is a member of the following medical societies: American Institute of Ultrasound in Medicine and American Roentgen Ray Society
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, The Angeles Clinic and Research Institute
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington
Felix S Chew, MD, MBA, EdM is a member of the following medical societies: American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

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