Slipped Capital Femoral Epiphysis (SCFE)
Summary
Slipped Capital Femoral Epiphysis (SCFE), also known as Slipped Upper Femoral Epiphysis (SUFE), is a Hip Disorder of Adolescence characterised by Displacement of the Femoral Head (Epiphysis) Posteroinferiorly Relative to the Femoral Neck through the Physis (Growth Plate). SCFE is the Most Common Hip Disorder in Adolescents, typically affecting Obese Boys Aged 10-16 Years. The aetiology is multifactorial, involving Mechanical Overload of the physis during the adolescent growth spurt. SCFE presents with Hip, Groin, Thigh, or Knee Pain and Limp. A classic sign is Obligate External Rotation of the hip on flexion. Diagnosis is confirmed by Plain Radiographs (AP and Frog-Leg Lateral) showing the slip. SCFE is classified as Stable (Able to weight-bear) or Unstable (Unable to weight-bear – Higher Avascular Necrosis risk). Treatment is Urgent Surgical Pinning (In Situ Fixation) to prevent slip progression. The Contralateral Hip Must Be Examined as bilateral involvement occurs in ~20-40%. [1,2,3]
Clinical Pearls
"Obese Adolescent Boy with Hip/Knee Pain = Think SCFE": Classic demographic. Knee pain referred from hip.
"Obligate External Rotation on Hip Flexion": Pathognomonic sign.
"Frog-Leg Lateral X-Ray is Essential": AP may miss subtle slips.
"Unstable = High AVN Risk": Cannot weight-bear. Urgent surgical stabilisation, But still high complication rate.
Demographics
| Factor | Notes |
|---|---|
| Incidence | ~10 per 100,000 adolescents. |
| Age | Boys: 12-16 years (Peak ~13). Girls: 10-14 years (Peak ~12). During adolescent growth spurt. |
| Sex | Male > Female (2-3:1). |
| Side | Left > Right. Bilateral: ~20-40% (Often sequential – Second hip within 18 months). |
| Obesity | Strong association. >80% are overweight or obese. |
Risk Factors
| Risk Factor | Notes |
|---|---|
| Obesity | Increased mechanical load on physis. |
| Male Sex | |
| Adolescent Growth Spurt | Physis relatively weak during rapid growth. |
| Endocrine Disorders | Hypothyroidism, Growth Hormone deficiency, Hypogonadism, Renal osteodystrophy. Consider if atypical age (less than 10 years) or bilateral. |
| Radiation | Prior pelvic radiotherapy. |
| Genetics | Family history in ~5%. |
Anatomy
- Femoral Head (Epiphysis): Ball of hip joint.
- Physis (Growth Plate): Cartilaginous growth plate at junction of epiphysis and metaphysis (Femoral neck).
- SCFE: Epiphysis Slips Posteriorly and Inferiorly relative to the femoral neck (Which appears to "slip" anteriorly and superiorly).
Mechanism
- Physeal Weakness: Adolescent growth spurt → Physis widened and relatively weak. Hormonal factors (Oestrogen closes physis, Testosterone may weaken).
- Mechanical Overload: Shear forces across physis (Exacerbated by obesity).
- Displacement: Femoral head slips posteroinferiorly.
Classification
| Classification | Criteria |
|---|---|
| Loder (Stability) | |
| - Stable | Able to Weight-Bear (With or without crutches). ~90%. Lower AVN risk (~less than 5%). |
| - Unstable | Unable to Weight-Bear. ~10%. High AVN Risk (~20-50%). |
| Duration (Fahey) | |
| - Acute | Symptoms less than 3 weeks. |
| - Chronic | Symptoms >3 weeks. |
| - Acute-on-Chronic | Chronic symptoms with acute worsening. |
| Severity (Southwick Angle) | Angle of slip on Frog-Leg Lateral. Mild less than 30°. Moderate 30-50°. Severe >50°. |
Symptoms
| Symptom | Notes |
|---|---|
| Hip / Groin Pain | |
| Thigh Pain | |
| Knee Pain | Common (~15-50%). Referred Pain. Can be the ONLY complaint – DO NOT MISS. |
| Limp | Antalgic. |
| Decreased Activity | |
| Duration | Variable. Weeks to months (Chronic) or Acute. |
Examination Findings
| Finding | Notes |
|---|---|
| Antalgic Gait / Limp | |
| Trendelenburg Gait | Gluteal weakness from hip dysfunction. |
| Affected Leg Externally Rotated | At rest. |
| Limited Hip Range of Motion | Especially internal rotation and flexion. |
| Obligate External Rotation on Hip Flexion | Drehmann Sign. Pathognomonic. Hip automatically rotates externally as it is flexed. |
| Leg Length Discrepancy | Affected leg may appear shorter. |
| Thigh Atrophy | If chronic. |
Imaging
| Modality | Notes |
|---|---|
| Plain Radiographs (First-Line) | BOTH AP Pelvis AND Frog-Leg Lateral (Or Cross-Table Lateral). |
| AP Findings: Klein's Line (Line along superior femoral neck should intersect lateral epiphysis – In SCFE, Does not). Widened physis. Decreased epiphyseal height. | |
| Frog-Leg Lateral (Most Sensitive): Best view for detecting slip. Posterior displacement of epiphysis. Southwick angle. | |
| CT / MRI | Rarely needed for diagnosis. MRI may detect very early (Pre-slip) changes. CT for complex deformity assessment. |
Contralateral Hip
- Always image BOTH hips. Bilateral in ~20-40%.
Laboratory (If Atypical)
| Test | Notes |
|---|---|
| TFTs | Exclude hypothyroidism (If less than 10 years or bilateral). |
| GH / IGF-1 | Growth hormone deficiency. |
| Renal Function | Renal osteodystrophy. |
Management Algorithm
SUSPECTED SCFE
(Adolescent with Hip/Groin/Knee pain, Limp, Obesity)
↓
PLAIN RADIOGRAPHS
- AP Pelvis AND Frog-Leg Lateral (BOTH Hips)
↓
SCFE CONFIRMED?
┌────────────────┴────────────────┐
YES NO
(Slip visualised) (Clinical suspicion high)
↓ ↓
- MRI (Early slip)
- Repeat imaging
- Close follow-up
↓
CLASSIFICATION
- STABLE (Can weight-bear) vs UNSTABLE (Cannot weight-bear)
- Severity (Southwick angle)
↓
TREATMENT: SURGICAL STABILISATION (All Cases)
┌──────────────────────────────────────────────────────────┐
│ **GOAL**: Prevent FURTHER Slip. Stabilise Physis. │
│ │
│ **STABLE SCFE** │
│ - **In Situ Pinning with Single Cannulated Screw** │
│ (Percutaneous, Fluoroscopy-guided) │
│ - Do NOT attempt to reduce (Reduces AVN risk) │
│ - Non-weight-bearing → Partial → Full as tolerated │
│ - Excellent outcomes │
│ │
│ **UNSTABLE SCFE** │
│ - **Urgent Surgical Stabilisation** │
│ - Gentle reduction (Controversial – Some advocate │
│ in situ pinning without forced reduction to minimise │
│ AVN risk) │
│ - Capsulotomy may decompress intracapsular pressure │
│ - High AVN risk (~20-50%) even with optimal treatment │
│ │
│ **SEVERE SLIP (>50°)** │
│ - In situ pinning OR │
│ - Consider later corrective osteotomy if significant │
│ residual deformity causing impingement │
└──────────────────────────────────────────────────────────┘
↓
CONTRALATERAL HIP
- Examine and image.
- **Prophylactic Pinning** controversial:
- Consider if high-risk: Endocrine disorder, Very young,
Long duration before physeal closure.
- Close surveillance otherwise.
↓
POST-OPERATIVE CARE
- Protected weight-bearing initially
- Physiotherapy
- Follow-up until physeal closure
- Monitor for AVN, Chondrolysis, Femoral Acetabular
Impingement (FAI) sequelae
↓
IF ATYPICAL (Age less than 10, Bilateral, No Obesity)
- Screen for Endocrine Disorders (TFTs, GH, Renal)
| Complication | Notes |
|---|---|
| Avascular Necrosis (AVN) of Femoral Head | Most serious. Compromised blood supply. Higher in Unstable SCFE (~20-50%). Leads to collapse, Degenerative arthritis. |
| Chondrolysis | Acute cartilage necrosis. Rapid joint destruction. Rare but devastating. |
| Femoral Acetabular Impingement (FAI) | From residual deformity (Cam impingement). Can lead to early OA. May require later osteotomy. |
| Slip Progression | If untreated or delayed treatment. |
| Contralateral SCFE | ~20-40% bilateral. Monitor until physeal closure. |
| Leg Length Discrepancy | |
| Osteoarthritis | Long-term. From AVN, Chondrolysis, FAI. |
| Factor | Notes |
|---|---|
| Stable SCFE (Treated) | Excellent outcomes with in situ pinning. Low AVN risk. |
| Unstable SCFE | High AVN risk despite treatment. Poorer long-term outcomes. |
| Severity | Mild/Moderate slips have better outcomes. Severe slips may have more impingement/OA. |
| Bilateral | Prophylactic pinning or close surveillance needed. |
Key Guidelines
| Guideline | Notes |
|---|---|
| AAOS / POSNA | In situ pinning for stable SCFE. Urgent stabilisation for unstable. Image both hips. |
What is SCFE?
SCFE (Slipped Capital Femoral Epiphysis) is a hip problem that affects teenagers, Usually during growth spurts. The ball of the hip joint (Femoral head) slips backwards and downwards from its normal position.
Who gets it?
- Mostly teenagers aged 10-16.
- More common in boys and in those who are overweight.
What are the symptoms?
- Pain in the hip, Groin, Thigh, Or even the knee.
- Limping.
- Leg may look turned outwards.
- Stiffness in the hip.
How is it treated?
Surgery is needed to stop the hip from slipping further. The surgeon puts a screw through the bone to hold the hip in place. If treated early and before complications, Most teenagers do very well.
Why is it important to diagnose quickly?
If SCFE is not treated, It can lead to serious problems like damage to the blood supply of the hip (Avascular necrosis) and long-term arthritis.
Will the other hip be affected?
It can be (In ~20-40% of cases), So the other hip is also checked.
Primary Sources
- Loder RT. Slipped capital femoral epiphysis. Am Fam Physician. 1998;57(9):2135-2142. PMID: 9606306.
- Loder RT, et al. Acute slipped capital femoral epiphysis: The importance of physeal stability. J Bone Joint Surg Am. 1993;75(8):1134-1140. PMID: 8354671.
- Aronsson DD, et al. Slipped capital femoral epiphysis: Current concepts. J Am Acad Orthop Surg. 2006;14(12):666-679. PMID: 17077339.
Common Exam Questions
- Classic Demographic: "Who is the typical patient with SCFE?"
- Answer: Obese Adolescent Male (12-16 years).
- Classic Sign: "What is the pathognomonic clinical sign of SCFE?"
- Answer: Obligate External Rotation on Hip Flexion (Drehmann Sign).
- X-Ray View: "Which X-ray view is most sensitive for diagnosing SCFE?"
- Answer: Frog-Leg Lateral (or Cross-Table Lateral).
- Treatment: "What is the treatment for stable SCFE?"
- Answer: In Situ Pinning with Single Cannulated Screw.
Viva Points
- Knee Pain = Hip Pathology: Always examine the hip in a child with knee pain.
- Klein's Line: On AP, Line along superior femoral neck should intersect epiphysis. Doesn't in SCFE.
- Unstable = High AVN Risk: ~20-50%. Cannot weight-bear.
- Bilateral in 20-40%: Image both hips. Monitor contralateral until physeal closure.
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