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Slipped Capital Femoral Epiphysis in an Obese Teenager

Edward W. Choung, MS; Frances Yang, DO

THE PHYSICIAN AND SPORTSMEDICINE - VOL 31 - NO. 7 - JULY 2003


In Brief: Adolescents are especially prone to develop slipped capital femoral epiphysis (SCFE). Hormonal changes in puberty, obesity, and hypogonadism suggest that endocrine dysfunction is a contributing factor. SCFE may be one of the most common disorders affecting the hip, yet the diagnosis is often missed or delayed as a result of inappropriate initial evaluation, as occurred in this report of a 13-year-old boy. Timely recognition and, typically, surgical intervention are critical to forestall progression and to prevent further complications.

An adolescent patient who is obese, demonstrates an antalgic limp, and reports hip, thigh, or knee pain may have several conditions, but the differential diagnosis should always include slipped capital femoral epiphysis (SCFE). The typical patient who has SCFE is obese and hypogonadic, but the condition also occurs in tall and thin adolescents who have had rapid linear growth.1 Prompt recognition of SCFE and immediate treatment are important to prevent progression and possible chronic disability from osteoarthritis later in life. Because the patient may have a long recovery period, treatment must address the orthopedic problem but also promote normal adolescent growth and development.

SCFE occurs when the shearing stress exerted on the femoral head is greater than the resistance provided by the mechanical stability of the growth plate. The femoral head displaces relative to the femoral neck, usually posteroinferiorly.2,3 Although the exact cause of SCFE is unknown, local trauma, inflammation, endocrine imbalances, and genetic features are possible contributing factors.3,4 The condition is fairly common in adolescents, especially boys, who have adiposogenital syndrome.

Case Report

A 13-year-old Hispanic boy came to our clinic because of increasingly acute left knee pain. He reported that he had been experiencing left thigh and knee pain for a year and a half. Another physician had previously told him that his knee pain was due to his obesity and that weight loss would relieve his symptoms. Because his family had no medical insurance, his parents had not sought further medical care.

The patient sustained trauma to the left knee while playing recreational football 1 week earlier; now the leg pain worsened whenever he attempted to bend the hip or knee. He was 4 ft 11 in. tall and weighed 184.5 lb (body mass index = 37 kg/m2). We noted an asymmetric and antalgic gait, and the left hip was externally rotated. A quick circumduction of the left hip was needed during midstride to complete forward motion. When lying supine, the patient held the left extremity in external rotation. Left hip range-of-motion testing revealed decreased internal rotation, abduction, and flexion. Moderate guarding was noted. Examination of the left knee demonstrated full range of motion, but pain referred to his left hip with movement. Exams of his right leg and back were normal.

Radiographs of the hips (figure 1) were consistent with SCFE. He was placed in a wheelchair to prevent further weight bearing on the affected joint and admitted to the hospital as an orthopedic patient. The next morning he had an open reduction and internal fixation of the slipped joint. The patient was discharged after an uncomplicated 1-week hospitalization. Long-term outcome for this patient is unavailable because he has been lost to follow-up.

Who Gets SCFE?

SCFE is a common condition affecting older children and adolescents that occurs twice as often in boys.4,5 The mean age at diagnosis is 13.5 for boys and 12.0 for girls, with a typical age range of 9 to 16 years.5 Hormonal factors may explain why SCFE is more common in boys and why it is rarely seen in girls after menarche.6 The vast majority of children who have SCFE are obese, and the added weight increases the shear stress across the physis.6 The African-American population shows increased incidence, and affected individuals tend to demonstrate adiposogenital syndrome characterized by obesity and hypogonadism.

The displacement takes place primarily at the hypertrophied cartilage layer of the physis where an increase in the thickness of the cell layer reduces its shear strength. Estrogens and androgens tend to decrease the thickness of the growth plate and, therefore, increase the shear strength. In contrast, growth hormone widens the growth plate and decreases shearing pressure. An adolescent who has adiposogenital syndrome has a deficiency of sex hormones and a greater risk for developing SCFE.7 The nature of the displacement may be gradual (chronic) and stable or sudden (acute or acute-on-chronic) and distinguished by instability.4,7

Clinical Evaluation

Patients who have SCFE commonly present with an antalgic limp characterized by a quick, short step on the involved side and a long step on the contralateral side. In addition, the lower limb is usually held in external rotation while standing, and limited internal rotation, flexion, and abduction of the hip are seen when supine.7 A hip that abducts and externally rotates upon passive flexion is suspected of SCFE until proven otherwise.7-10

In chronic SCFE, pain is usually dull and intermittent, lasts 3 weeks or more, is perceived in the anteromedial thigh, and frequently radiates to the medial knee. In acute SCFE, the clinical picture differs, with the onset of pain being sudden, sharp, severe, persistent, and often accompanied by an inability to bear weight on the affected leg.4,7 Up to 60% of patients have bilateral involvement, but the slips may not occur simultaneously.7,11 The actual diagnosis is confirmed by radiographic examination of the affected hip, with the displacement best visualized in a lateral projection, such as frog-leg, Lowenstein (frog-lateral), or true lateral.

Any older child or adolescent who demonstrates a limp or has pain in the hip, groin, thigh, or knee should be evaluated for SCFE, especially if the patient is overweight. SCFE has the potential for long-term, crippling sequelae. Early recognition is an important controllable factor that is often missed or delayed, resulting in progression of the slip. Common errors during the initial evaluation include not obtaining hip radiographs, misreading of hip radiographs, and failing to make a timely orthopedic referral. Early surgical intervention may greatly reduce complications.11

Treatment of SCFE

Following the diagnosis of either chronic or acute SCFE, the patient should be placed in a wheelchair to avoid any weight bearing and admitted to the hospital on an emergency basis. Surgery is the recommended treatment for SCFE. Before surgery, the patient may be placed in a Buck's or Russell traction device to correct internal rotation of the affected extremity and to reduce any accompanying muscle spasms.1

Surgical fixation of the slipped epiphysis is usually performed with one cannulated screw inserted perpendicular to the epiphyseal plate and through the center of the epiphysis.7 The objective of this procedure is to prevent further slippage by transfixing the epiphysis and promoting closure of the physis. In a thin individual, a percutaneous approach may be performed to lessen the dissection and size of scar. Moderate displacements between 30° and 50° had been corrected by femoral neck osteotomy, but this technique has a high risk of avascular necrosis and is no longer performed.7

The epiphyseal plate of the femoral head contributes less than 30% of the total length of the femoral shaft12; premature fusion of a physis resulting in growth retardation is uncommon when surgery is performed close to skeletal maturity.

Following internal stabilization with a cannulated screw, the patient may begin partial weight bearing with crutches, eventually advancing to full weight bearing as tolerated. Most patients are able to walk without crutches within 2 to 4 days. More important, when compared with femoral neck osteotomy, internal fixation significantly reduces the risk of morbid postoperative complications of avascular necrosis and chondrolysis.6

Historically, nonsurgical management of SCFE has demonstrated good results.13 One such treatment requires placing the patient in a bilateral hip spica cast to provide complete hip immobilization in the desired position for 8 to 16 weeks. Although a reduction in the risk of developing contralateral SCFE has been documented, more recent studies of the hip spica cast demonstrate the increased risk of chondrolysis, full-thickness cast pressure sores, and further slippage of the involved hip, discouraging spica cast use for the treatment of SCFE.6 Furthermore, the numerous cast removal and reapplication cycles necessary for radiologic exams were found to be cumbersome to the family, especially with an obese patient. Sex hormone therapy to achieve closure of the physis is another alternative that may be indicated for poor surgical candidates.

Prognosis

Untreated cases of SCFE may often result in progression of the slip with stabilization following physeal closure.7,11 The degree of slippage determines the extent of the deformity, and greater slippage increases the risk of osteoarthritis later in life.

The outcome of surgical intervention is usually good, with little or no restriction of hip function despite the residual deformity of the proximal femur. Occasionally, in a patient who has a severe slip and loss of motion, a subtrochanteric or intertrochanteric osteotomy may be required.7 Osteotomy, however, is usually delayed for a few years to permit remodeling of the femoral head and joint capsule.

Chondrolysis and avascular necrosis are the most common complications of surgical intervention and may also occur from untreated SCFE. Chondrolysis may be self-limiting and resolve after 1 to 2 years, but it more commonly progresses to ankylosis, requiring hip fusion or hip replacement. Although avascular necrosis is less common, it is a more serious complication that often results in irreversible deformity and eventual osteoarthritis, possibly requiring similar surgical intervention.11 For a patient who has surgery with the cannulated screw, the prognosis for activity depends on postoperative rehabilitation. Treatment restores mobility, no long-term restrictions are usually imposed, and the patient may do activities as tolerated. Patient education about exercise and healthy lifestyle choices is vital for maximum positive outcome.

Timely Identification Is Key

SCFE is a disorder that primarily affects adolescents and older children, especially those who are obese or have endocrine imbalances. SCFE has the potential for significant long-term morbidity. Differential assessment of a painful limp should focus on excluding conditions that entail significant morbidity and mortality (eg, from a fall or postoperative infection and sepsis). With early identification and timely surgical intervention, the prognosis of SCFE is good.

References

  1. Benchot R: The adolescent with slipped capital femoral epiphysis. J Pediatr Nurs 1996;11(3):175-182
  2. Kordelle J, Richolt JA, Millis M, et al: Development of the acetabulum in patients with slipped capital femoral epiphysis: a three-dimensional analysis based on computed tomography. J Pediatr Orthop 2001;21(2):174-178
  3. Pellecchia GL, Lugo-Larcheveque N, Deluca PA: Differential diagnosis in physical therapy evaluation of thigh pain in an adolescent boy. J Orthop Sports Phys Ther 1996;23(1):51-55
  4. Morrissy RT: Slipped capital femoral epiphysis, in Lovell WW, Winter RB, Morrissy RT, et al (eds): Pediatric Orthopaedics. Philadelphia, Lippincott-Raven, 1996, pp 993-1019
  5. Loder RT, Greenfield ML: Clinical characteristics of children with atypical and idiopathic slipped capital femoral epiphysis: description of the age-weight test and implications for further diagnostic investigation. J Pediatr Orthop 2001;21(4):481-487
  6. Loder RT, Aronsson DD, Dobbs MB, et al: Slipped capital femoral epiphysis. J Bone Joint Surg Am 2000;82(8):1170-1188
  7. Tachdjian MO: Slipped capital femoral epiphysis, in Clinical Pediatric Orthopedics: The Art of Diagnosis and Principles of Management. Stamford, CT, Appleton & Lange, 1997, pp 223-233
  8. Crawford AH: Slipped capital femoral epiphysis. J Bone Joint Surg Am 1988;70(9):1422-1427
  9. Kendig RJ, Field L, Fisher LC III: Slipped capital femoral epiphysis, a problem of diagnosis. J Miss State Med Assoc 1993;34(5):147-151
  10. Ledwith CA, Fleisher GR: Slipped capital femoral epiphysis without hip pain leads to missed diagnosis. Pediatrics 1992;89(4 pt 1):660-662
  11. Causey AL, Smith ER, Donaldson JJ, et al: Missed slipped capital femoral epiphysis: illustrative cases and a review. J Emerg Med 1995;13(2):175-189
  12. Gartland J: Fundamentals of Orthopedics, ed 4. Philadelphia, WB Saunders, 1979, p 346
  13. Betz, RR, Steel HH, Emper WD, et al: Treatment of slipped capital femoral epiphysis: spica-cast immobilization. J Bone Joint Surg Am 1990;72(4):587-600


Mr Choung is a second-year medical student and Dr Yang is the chair of pediatrics at Western University of Health Sciences in Pomona, California. Dr Yang is also an assistant clinical professor of pediatrics at Arrowhead Regional Medical Center in Colton, California. Address correspondence to Frances Yang, DO, Dept of Pediatrics, 309 E Second St, Pomona, CA 91766-1854; e-mail to [email protected].

Disclosure information: Mr Choung and Dr Yang disclose no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.


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