Slipped Capital Femoral Epiphysis

The clinical picture is sometimes confusing since the anatomical abnormality does not always reflect the location of the pain, which is observed in the groin, thigh, or knee. The latter is the most frequently affected site. In fact, most patients with SCFE are teenagers with knee or hip pain [6] who subsequently exhibit an intermittent limping gait. On presentation, the pain is of several weeks duration. Also, in the majority of cases, there is a minor trauma that highlights the limp and the pain.

On physical exam, there is a limited range of motion of the hip. The abnormal hip joint causes patients to walk with foot and hip facing outward. When evaluating the patient, SCFE is classified according to whether it is acute or chronic, stable versus unstable in terms of ability to bear weight on it, and radiographic findings.

Unstable acute SCFE will present with severe pain to the extent that patients cannot bear weight on leg. This is more common after trauma. MRI is helpful to diagnose this [7]. Furthermore, unstable patients tend to develop complications.  

An atypical patients exceed the usual age range. More specifically, the ages are younger than 10 years old or older than 16 years of age. Also physical characteristics such as short stature are considered atypical.

Complications

• Shortly after the onset of SCFE symptoms, chondrolysis may develop [8]. This consequently develops a stiff and painful hip regardless of whether surgery is performed.
• Another complication, avascular necrosis of the capital femoral epiphysis [9] occurs when SCFE progresses rapidly and blood vessels become damaged. This results in the degeneration and deformity of the epiphysis and hence the development of arthritis.
• Common presentations with older ages of SCFE patients include arthritis, and more specifically, osteoarthritis of the hips.

A thorough history and physical exam are necessary. Pain of the knee or hip in children or teenagers with no obvious cause should elevate suspicion for SCFE. Therefore these components along with pelvic radiographs are necessary for accurate diagnosis. X-rays depict the epiphyseal slip [10].

Physical findings include limited range of hip movement and external rotation of leg with hip flexion. Functionality of hip joints is correlated to the amount of epiphyseal slips. Greater difficulty is expected with pronounced slips.

Laboratory studies are not indicated to perform routine endocrine screening on SCFE patients. However, in patients with atypical presentations or manifestations suggestive of endocrine abnormalities, appropriate laboratory studies are indicated. Possible disorders include hypothyroidism, growth hormone deficiency, pituitary tumors, renal osteodystrophy and others as well.

Imaging

Specific lines are drawn on anteroposterior and frog-lateral X-ray views of pelvis and hips to determine anatomical abnormality. These provide critical findings indicative of SCFE. There are three types describing the level of slippage. Type I is associated with less than 33% displacement of head off the femoral neck, type II with 33-50% displacement, while type III is greater than 50% displacement.

In addition, X-rays will demonstrate any abnormalities of femoral neck and head that resulted from the modified mechanics of SCFE. Furthermore, preexisting medical conditions may be detected as well. The radiograph is the test of choice. Other modes of imaging such as bone scans, MRI [10], and CT scans can provide information on the percentage of slippage and blood supply to the epiphyseal plate. Experts advocate for the utilization of MRI in SCFE patients since it may detect certain features such as joint effusion and synovitis that a radiograph may not demonstrate [7]. It is thought that MRI can provide insight during the planning of surgical intervention [7].

The treatment of SCFE is surgery, which is crucial. It considered to be emergent and should be conducted soon after diagnosis. The surgical procedure consists of internal in situ fixation of the epiphysis with one cannulated screw. This fixation will stabilize and avoid further slippage [5]. In some cases, it may be advisable to prophylactically perform the fixation on the contralateral hip [11]. This will depend on the individual and the risk factors present. In cases with severe deformity, further surgical intervention may be necessary. In addition, some patients may need revisions if the initial screw is “outgrown.”

Symptomatic relief and conservative measures do not treat the underlying issues but are helpful for patient comfort. However, surgery is the ultimate treatment. Furthermore, SCFE patients have successful outcomes following immediate in situ fixation. It improves the quality of life and reduces morbidity [5] although complications may still arise in those with severe slippage and deformity. Avascular necrosis, chondrolysis, and osteoarthritis are some of the long term complications.

Patients with severe complications may need salvage hip arthrodesis. Individuals with partially damaged hips may benefit from proximal osteotomies which shift forces to undamaged areas of the femoral head.

While most cases of SCFE are idiopathic, there are risk factors attributed to SCFE. The strongest risk factor is obesity. In fact, most individuals affected with SCFE are obese [3]. The excess weight applies marked shear forces across the physis and weakens it.

Endocrine disorders and rapid growth spurts are also risk factors. Physiologically, the physis becomes weakened during puberty [3], likely due to the effects of hormones. For example, testosterone reduces the strength of the physis which reflects the higher incidence in males. In contrast, estrogen strengthens the shaft, explaining the lower incidence of SCFE in females. The disorder is not hereditary.

Prevalence is 10.8 cases per 100,000 children [2]. Furthermore, SCFE is more common in males than females. The average age of diagnosis differs in both genders, 13.5 years in males and 12 years of age in females. With regards to race, it is more common in African Americans and Pacific Islanders, which may be correlated to obesity in these populations.

In the northern region of the United States, there are higher rates of SCFE in summer and fall, which is likely related to increased physical activity. It is estimated that 18 to 50% of individuals with SCFE present with bilateral involvement. Some will present unilaterally initially but become bilateral over time [4]. 

Multiple factors play a role in the changes of the physis, including obesity, accelerated growth during puberty, and endocrine disorders. Any one of these factors apply stress on the hip joint by directing shear force at the growth plate. More specifically, the excess weight, stress from growth spurt and fluctuating hormones all lead to anterior and superior displacement of the metaphysis. The widened epiphysis in SCFE results from the enlargement of the hypertrophic zone. Furthermore, this zone in a normal physis is usually 15% to 30% whereas it can reach up to 80% in SCFE patients.

Arising from the hypertrophic zone is abnormal cartilage development, endochondral ossification, and perichondral ring instability. These all contribute to the weakened cartilage structure overall, which is the site where slippage emerges.

Normally during growth in children and teenagers, the physis shifts position from horizontal to oblique. This positional change replaces compression forces with shear forces. Hence, these mechanical shifts intensify shear forces on the hip joint and produce SCFE [4]. 

There is no prevention as most cases are idiopathic. However, children and adolescent with risk factors such as obesity are highly advised to reduce weight. In fact, weight loss is pertinent for improvement of overall health and reduces the risk of metabolic syndrome.  

Slipped capital femoral epiphysis (SCFE) is an anatomical hip disorder characterized by slippage of the proximal epiphysis through the epiphyseal plate. This affects preadolescents and adolescents in the age range of 8 to 15 years of age [1]. Most cases have no known cause, however, there are predisposing risk factors such as obesity, endocrine disorders, and rapid growth during puberty. Hence, it is likely that hormonal effects on the growth plate weakens it. 

Suspicion for SCFE should be elevated in children and adolescents with pain in the knee, hip or groin and/or a limp not attributed to any apparent etiology. Furthermore, SCFE can manifest unilaterally or bilaterally with sequential involvement as well.  Pelvic /hip radiographs and possibly other imaging modalities are used for diagnosis. Any delays in the diagnosis can be detrimental due to the potential complications.

SCFE is classified according to the the amount of stability, duration of symptoms and whether the patient can apply weight on the affected extremity. As expected, stable SCFE is correlated with a better prognosis [2]. Accurate and prompt recognition is essential to prevent further damage and subsequent complications. As soon as diagnosis is established, surgery should be performed. 

Slipped capital femoral epiphysis (SCFE) is a disorder that affects the hip(s) of teenagers. The anatomy of the hip is altered in which the upper thigh bone slips in the backward direction. This occurs with growth spurts in puberty or obese individuals. The cause in most patients is not known. It is more common in boys than girls, which may be due to hormone changes. 

While SCFE may develop slowly, in some cases it occurs rapidly after a fall or minor trauma. Patients present to the doctor with vague pain that could be located in hip, groin, or knee. Usually the pain is in the knee. Patients may also have a limp that comes and goes. In certain cases, the patient cannot bear weight on the leg. Patients may have one or both legs involved. Some will initially have one affected leg and then develop SCFE in the other leg at a later point. 

SCFE is diagnosed through a detailed history and physical exam. Patients do not have full range of motion of the affected hip(s) and the leg is usually tuned outwards. The doctor will order an X-ray of the hips and pelvis. Some patients that may have other diseases as well and therefore the doctor will order special laboratory tests. 

As soon as SCFE is diagnosed, a pediatric orthopedic surgeon will perform urgent surgery to avoid further damage or complications. The surgical procedure consists of a screw insertion on the hip bone to prevent any more slipping and provide stabilization. 

1. Gholve PA, Cameron DB, Millis MB. Slipped capital femoral epiphysis update. Current Opinion in Pediatrics. 2009; 21(1):39–45. 
2. Lehmann CL, Arons RR, Loder RT, Vitale MG. The epidemiology of slipped capital femoral epiphysis: an update. Journal of Pediatric Orthopaedics. 2006; 26(3):286–290.
3. Loder RT, Richards BS, Shapiro PS, et al. Acute slipped capital femoral epiphysis: the importance of physeal stability. Journal of Bone and Joint Surgery. 1993; 75(8):1134-1140.
4. Zupanc O, Krizancic M, Daniel M, et al. Shear stress in epiphyseal growth plate is a risk factor for slipped capital femoral epiphysis. Journal of Pediatric Orthopaedics. 2008 Jun; 28(4):444-51.
5. Aronson DD, Carlson WE. Slipped capital femoral epiphysis. A prospective study of fixation with a single screw. Journal of Bone and Joint Surgery. 1992; 74(6):810-9.
6. Reynolds RA. Diagnosis and treatment of slipped capital femoral epiphysis. Current in Opinion Pediatrics. 1999; 11(1):80–83.
7. Tins B, Cassar-Pullicino V, McCall I. The role of pre-treatment MRI in established cases of slipped capital femoral epiphysis. European Journal of Radiology. 2009;70(3):570-8.
8. Loder RT, Aronsson DD, Dobbs MB, et al. Instructional course lecture: slipped capital femoral epiphysis. Journal of Bone and Joint Surgery. 2000;82:1170-1188.
9. Nisar A, Salama A, Freeman JV, et al. Avascular necrosis in acute and acute-on-chronic slipped capital femoral epiphysis. Journal of Pediatric Orthopaedics. 2007; 16(6):393-398.
10. Dwek JR. The hip: MR imaging of uniquely pediatric disorders. Magnetic Resononance Imaging in Clinical North America. 2009; 17(3):509-20.
11. Loder RT. Controversies in slipped capital femoral epiphysis. Orthopedic Clinics of North America. 2006; 37(2):211-21.