|Year : 2015 | Volume
| Issue : 1 | Page : 72-76
Early diagnosis of slipped capital femoral epiphysis on magnetic resonance imaging: A case report with review of literature
Sanjay M Khaladkar, Preeti Sherawat, Mansi N Jantre, Dhaval K Thakkar, VM Kulkarni
Department of Radio-Diagnosis, Dr. D Y Patil Medical College, Hospital and Research Centre, Dr. D Y Patil Vidyapeeth, Pune, Maharashtra, India
|Date of Web Publication||8-Jan-2015|
Sanjay M Khaladkar
Flat No. 5, Plot No. 8, S. No. 26/A, Tejas Bldg, Sahawas Society, Karve Nagar, Pune - 411 052, Maharashtra
Source of Support: None, Conflict of Interest: None
Slipped capital femoral epiphysis (SCFE) is a common hip condition occurring in adolescents, with a prevalence of 10 cases per 100,000 children. It usually affects younger age group from 10 to 17 years. The condition is usually found to be coexistent with various other conditions such as obesity, growth surges, and endocrine disorders such as hypothyroidism, growth hormone supplementation, hypogonadism, and pan-hypopituitarism. Patients present with limping and a poorly localized pain in the hip, groin, thigh, or knee. Diagnosis of the condition is often delayed due to its nonassociation with trauma and hence increases the chances of developing various complications such as avascular necrosis, chondrolysis and deformity. Majority of researches of SCFE are from Europe and North America, while studies in Asian populations are rare. Delay in diagnosis of SCFE is usually due to patients presenting with knee pain. Imaging can thus aid in early diagnosis and appropriate treatment of the disease, which in turn reduces incidence of deformity and disability in the affected children. Bilateral hip radiography - anteroposterior and frog's-leg lateral views and magnetic resonance imaging (MRI) are the radiological techniques that help in early diagnosis. MRI detects early physeal changes of both preslip and SCFE even when radiographs and computed tomography are normal. MRI should be routinely used to diagnose early SCFE in preslip stage to avoid further complications.
Keywords: Magnetic resonance imaging, slipped capital femoral epiphysis, X-rays
|How to cite this article:|
Khaladkar SM, Sherawat P, Jantre MN, Thakkar DK, Kulkarni V M. Early diagnosis of slipped capital femoral epiphysis on magnetic resonance imaging: A case report with review of literature. Med J DY Patil Univ 2015;8:72-6
|How to cite this URL:|
Khaladkar SM, Sherawat P, Jantre MN, Thakkar DK, Kulkarni V M. Early diagnosis of slipped capital femoral epiphysis on magnetic resonance imaging: A case report with review of literature. Med J DY Patil Univ [serial online] 2015 [cited 2020 Sep 18];8:72-6. Available from: http://www.mjdrdypu.org/text.asp?2015/8/1/72/148855
| Introduction|| |
Slipped capital femoral epiphysis (SCFE) also known as slipped upper femoral epiphysis is one of the most common adolescent hip disorders and represents a unique type of instability of proximal femoral growth plate presenting with hip, thigh, or knee pain. Ernst Mueller (1889) was first to describe it pathologically using dissected specimens. The diagnosis depends on the age, clinical presentation and radiographic findings. SCFE is the most common hip disorder in adolescents, usually occurring between 10 and 17 years of age. The condition is defined as the posterior and inferior slippage of the proximal femoral epiphysis on the metaphysis (femoral neck), which occurs through the epiphyseal plate (growth plate). Any adolescent patient presenting with limp and complaints of pain in hip, groin, thigh, or knee should be considered to have SCFE unless proven otherwise. Both hips should be examined closely so as not to miss potential bilateral cases.
| Case Report|| |
The case we present here is a 15-year-old male patient presented with pain in right hip since 2 months. The onset of pain was insidious, radiating to right thigh which aggravated on movement and was not relieved on medication. Patient had a limping gait. There was however, no history of any antecedent trauma or fall. There was no history of fever, weight loss, and chronic cough. Routine laboratory investigations were normal. Following this, radiograph of pelvis with both hips anteroposterior (AP) view, frog's lateral view and right lateral view of the right hip joint was done.
Radiographs revealed subtle widening of the physis on the right side on AP view [Figure 1]a posterior and medial displacement of the epiphysis of the right femur with respect to femoral neck on lateral view and frog's lateral view [Figure 1]b and c. Diagnosis of SCFE was made on X-ray. Magnetic resonance imaging (MRI) was suggested for confirming the diagnosis.
|Figure 1: Radiographs showed subtle widening of the physis on the right side on anteroposterior view, (a) posterior and medial displacement of the epiphysis of the right femur with respect to femoral neck on lateral (b) and frog's lateral view (c)|
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Coronal T1-W1, T2-WI [Figure 2]a and b; Axial T1-WI, T2-WI [Figure 3]a and b]; short-tau inversion recovery (STIR), gradient-recalled echo, dual echo steady state; sagittal T1-WI and T2-WI [Figure 3]c and d MRI images were observed. Superior growth plate appeared widened with slightly ill-defined margins. Adjoining bone marrow revealed altered marrow signals appearing hypointense on T1-WI and hyperintense on STIR which was suggestive of bone marrow edema. Femoral capital epiphysis was displaced posteriorly and medially with respect to metaphysis. Hence, metaphysis appeared more anteriorly placed. Femoral capital epiphysis showed normal signal intensity. Grade II synovial effusion was noted. Hip joint space and acetabulum appeared normal. Periarticular soft-tissues were normal. Left acetabulum, hip joint space, femoral capital epiphysis, superior growth plate, and metaphysis appear normal with normal signal intensity. There was no synovial effusion. Periarticular soft-tissues appeared normal. Bilateral sacroiliac joints and visualized muscles and fat planes were normal. A diagnosis of right SCFE was made.
|Figure 2: Coronal TI-WI (a) and T2-WI (b) magnetic resonance imaging images reveals physeal widening with indistinct margins and adjoining bone marrow edema|
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|Figure 3: Axial TI-WI (a), T2-WI (b), Sagittal TI-WI (c) and T2-WI (d) magnetic resonance imaging images reveal posterior and medial displacement of femoral capital epiphysis with respect to metaphysis with physeal widening with indistinct margins and adjoining bone marrow edema|
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| Discussion|| |
In SCFE, epiphysis stays in the acetabulum while the neck displaces anteriorly and rotates externally (hence, epiphysis is posterior and medial with respect to metaphysis). It is most common hip disorder in adolescence. Its incidence is 10/100,000 children per year.  SCFE is uncommon in India, its exact incidence is unknown.  Incidence of SCFE is increasing and the age at presentation is decreasing worldwide. It commonly occurs in boys of 10-17 years of age.  Peak age is 13 years for boys and 11.5 years for girls. It is 3 times common on boys. Left hip is more commonly affected than the right; it is seen bilaterally in 20-40% of cases. Incidence of bilateral involvement is 37%.  Significant association between subnormal vitamin D level and SCFE in adolescence from India is found.
It is caused by increased force applied across the epiphysis, or a decrease in the resistance within the physis to shearing. Mechanical risk factors are obesity, coxa profunda, femoral, and acetabular retroversion.  Half of SCFE patients are at or above 90th percentile for weight, about 70% over 80th percentile. 51-77% of children with SCFE are obese. Endocrine diseases (seen in 5-8% of SCFE cases) are hypothyroidism, hypopituitarism, growth hormone deficiency, pseudohypoparathyroidism, vitamin D deficiency, renal failure, and renal osteodystrophy weakens the physis due to associated secondary hyperparathyroidism.  Endocrine workup should be done if child less than 10 years of age, post pubertal and weight less than 50th percentile. Diagnosis of SCFE in pre and postpubertal cases should raise suspicion for underlying metabolic or systemic abnormalities. Majority are idiopathic. Neglected septic arthritis may also cause SCFE.
Slipped capital femoral epiphysis is a Salter Harris type I fracture through proximal femoral physis and is due to repeated trauma on a background of mechanical and probably hormonal predisposing factors and an intrinsic weakness in hypertrophic zone of physeal cartilage. Stress around the hip causes a shear force to be applied across the growth plate. Slippage occurs through the hypertrophic zone of the physis. During growth spurt, there is widening of the physeal plate. The axis of the physis alters during growth and becomes oblique from horizontal. As the physis becomes more oblique shear force across the growth plate increases resulting in an increased risk of fracture with resultant slippage. This leaves the proximal femoral epiphysis located in the acetabulum displaced posteriorly and medially related to femoral neck. Because the physis has yet to close, the blood supply to the physis still should be derived from femoral neck, the supply is tenuous in the late childhood and frequently lost after the fracture occurs.  Manipulation of the fracture frequently results in osteonecrosis and chondrolysis because of tenuous nature of the blood supply. Osteonecrosis affects 17-47% cases of SCFE greater risk of arthritis of hip joint later in life.
Patient presents with discomfort, hip, groin pain, medial thigh or knee during walking (knee pain is referred from hip joint; pain is accentuated on running, jumping or pivoting activities). In preslip stage patient has slight discomfort. In acute phase, patient presents with severe pain, limited hip motion (especially reduced internal rotation, abduction and flexion of affected hip) due to pain and alteration in gait with external rotation of leg. In acute on chronic phase, patient presents with pain, limp, and altered gait occurring for several months, suddenly becoming very painful. In chronic phase, child is able to walk with altered gait, knee pain, external rotation of leg, while walking in mild cases, mild to moderate shortening of the affected leg and atrophy of thigh muscles. 20% of SCFE patient present with initial bilateral involvement, another 10-20% patients develop a contralateral slip on an average of 18 months after an initial one.
Differential Diagnosis includes Perthe's disease, acute transient synovitis, septic arthritis, osteomyelitis, and fracture neck femur, stress fracture of the femoral neck, apophyseal avulsion fracture, hip apophysitis, osteitis pubis, and injury to groin.
Complications include chondrolysis (degeneration of articular cartilage) seen in 5-8% of slips. Specific risk factors are - severe slips, African American race, female gender, body cast immobilization, screw penetration of articular cartilage, femoral neck osteotomy. Avascular necrosis (AVN) of epiphysis occurs in 10-25% of cases, associated with attempts to reduce displaced epiphysis before treatment and with osteotomy of femoral neck.  Severe varus deformity with femoral neck shortening and broadening leading to secondary osteoarthritis and premature epiphyseal fusion with resultant femoral shortening may also be seen.
| Classification|| |
- Loder classification - stable vs. unstable ([Table 1]) 
- Classification based on Duration (temporal classification, traditional clinical classification) - Fahey and O'Brian 
- Preslip (prodromal)
- Acute (symptoms that persist for <3 weeks) - 10% of SCFE
- Chronic (symptoms that persist for >3 weeks - 85% of SCFE
- Acute on chronic - chronic with sudden exacerbation
- [Table 2] shows classification based on anatomic displacement - Grading system: Linear and angular.
|Table 2: Classifi cation based on anatomic displacement-grading system: Linear and angular|
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Severity is slip correlates with amount of displacement of epiphysis measured in thirds of total width of femoral neck as described by Wilson and with angle of displacement on frog's lateral X-ray of hip. 
X-ray signs are widening and irregularity of the growth plate as compared to the uninvolved side, decreased epiphyseal height compared with the uninvolved side, steel sign (Steel's metaphyseal blanching) - seen on AP radiograph as a double density found at metaphysis caused by posterior slip of epiphysis being superimposed on metaphysis, lesser trochanter prominence - caused by external rotation of femur, Kleins line (Trethowan's sign) - on AP radiograph, a line drawn along superior edge of the femoral neck should normally cross the epiphysis. In SCFE, there is failure of Klein's line to intersect with femoral epiphysis, loss of triangular sign of Capener. No remodeling is seen in acute SCFE. Rounding of the superior portion of femoral neck, callus at epiphyseal and metaphyseal junction in chronic SCFE. Wilson method Southwick angle method are used for grading based on linear and angular displacement respectively. 
In a stable slip, standard X-ray requested is AP and frog's-leg view. In potentially unstable slip, care should be taken not to exacerbate the slip by placing the limb in frog's-leg position, in this situation; a shoot through lateral view is performed. A frog's-leg lateral view will be inaccurate in presence of pain and spasm of affected hip. In frog's lateral view, a line drawn through center of neck should meet the center of epiphysis proximally. If it meets anterior to it SCFE is likely. Early slip is difficult to diagnose on X-ray. AP view can detect only on inferior and medial slip. 
Diagnosis of SCFE may be missed or delayed if only AP radiographs are obtained. Kleins line is not a sensitive diagnostic test for SCFE. In 14 out of 23 hips (61%) with SCFE, Kleins line was normal on AP radiograph despite SCFE being evident by the Southwick angle on lateral radiograph. Early slips tend to occur in posterior direction and these are best seen on lateral view of hip, but these are difficult to obtain. When evaluating adolescents with hip or thigh pain, lateral radiograph is necessary.
The earliest way to detect SCFE is by using MRI. One of the risk factors for the incidence of SCFE in children of the age group of 10 years and more is the change of shape of proximal femoral growth plate from pleated to more spherical. Along with hormonal, biochemical and genetic reasons it leads to SCFE in children 10 years old and older.  MRI detects early physeal changes of both preslip and SCFE even when radiographs and computed tomography are normal.  With MRI early marrow edema, physeal widening and slippage can be demonstrated. Diagnosis of SCFE can be done with MRI with high clinical suspicion of SCFE in preslip stage when X-ray is inconclusive. It is useful in diagnosing complications (like chondrolysis and AVN, femoroacetabular impingement), detecting SCFE in contralateral asymptomatic hip, follow up imaging of contralateral hip, postoperatively to evaluate physeal closure and to rule out differential diagnosis in atypical presentation.
Signs on MRI are physeal widening on T1-WI, bone marrow edema in adjoining neck (appearing hypointense on T1-WI and hyperintense on T2-WI and STIR), posterior and medial displacement of femoral head with respect to neck. Degree of slippage can be assessed. Joint effusion appears hyperintense on T2-WI and STIR. Changes in contralateral hip can be detected even if only one hip is symptomatic. Bilateral changes are common. Complications of SCFE like AVN and chondrolysis, and metaphyseal impingement on anterior rim of acetabulum can be detected. ,,
Majority of researches of SCFE are from Europe and North America, while studies in Asian populations are rare. Delay in diagnosis of SCFE is usually due to patients presenting with knee pain. Hence, MRI should be routinely used to diagnose early SCFE in preslip stage to avoid further complications. 
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]