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Paediatric Orthopaedics
Emergency Medicine
EMERGENCY

Slipped Upper Femoral Epiphysis (SUFE)

High EvidenceUpdated: 2025-12-25

On This Page

Red Flags

  • Unstable Slip (Inability to weight bear - High AVN risk)
  • Atypical Age (<10 or >16 - endocrine screen)
  • Knee pain (Hip pathology until proven otherwise)
Overview

Slipped Upper Femoral Epiphysis (SUFE)

[!WARNING] Medical Disclaimer: SUFE is an orthopaedic emergency. Unstable slips have a 50% risk of AVN. Do not allow the patient to walk. Wheelchair only.

1. Clinical Overview

Definition

SUFE (or SCFE in the US) is a fracture through the physis (growth plate) of the femoral head.

  • The Metaphor: The femoral head (ice cream scoop) stays in the acetabulum, but the femoral neck (cone) slips anteriorly and superiorly.
  • Result: The Head appears to slip Posteriorly and Inferiorly.

Epidemiology

  • Incidence: 10 per 100,000.
  • Age: 10-15 years (The adolescent growth spurt).
  • Gender: M:F = 1.5:1.
  • Weight: >90% are obese (>95th centile).
  • Bilateral: 20-40% at presentation. Up to 60% eventually.

Classification (Loder)

Crucial for prognosis.

  1. Stable: Patient CAN walk (even with crutches). AVN Risk <10%.
  2. Unstable: Patient CANNOT walk. AVN Risk 50%. (Essentially a hip fracture).
2. Pathophysiology

Why does it happen?

  • Mechanical: Obesity places excessive shear force on the hip.
  • Hormonal:
    • Growth Hormone: Thickens the physis (weakens it).
    • Sex Hormones: Usually close the physis.
    • The "Window of Vulnerability": During the growth spurt, the physis is wide and weak, but the body is heavy (obesity).
  • Endocrine Causes (Screen if <10 yrs or thin):
    • Hypothyroidism.
    • Growth Hormone Deficiency.
    • Renal Osteodystrophy.
3. Clinical Presentation

The "Classic" Patient

Physical Exam

  1. Gait: Antalgic. Externally rotated foot.
  2. Drehmann's Sign:
    • Flex the hip to 90 degrees.
    • Positive: The hip involuntarily goes into External Rotation. (The anatomy forces it out).
  3. ROM: Loss of Internal Rotation. Loss of Abduction.
Obese adolescent male.
Common presentation.
Limping for weeks/months.
Common presentation.
Pain in the Knee (Obturator nerve referral).
Common presentation.
4. Investigations

X-Ray (AP and Frog-Leg Lateral)

The Frog-Leg view is the most sensitive.

Assessing the X-Ray

  1. Klein's Line:
    • Draw a line along the superior edge of the femoral neck.
    • Normal: The line should intersect the femoral head.
    • SUFE: The line passes above the femoral head (The Trethowan Sign).
  2. Epiphysis Height: Looks shorter on AP (because it has tilted back).
  3. Blanch Sign of Steel: Double density at the metaphysis.

MRI

  • Used for "Pre-slip" (Painful hip, normal X-ray, but physis oedema).
5. Management

Immediate

  1. Stop Walking: Wheelchair immediately. Further slippage increases AVN risk.
  2. Admit: Orthopaedics.

Surgical: In Situ Fixation

  • Goal: Prevent further slip. Fuse the physis.
  • Technique: Percutaneous single Cannulated Screw.
  • Reduction?: NO.
    • Do NOT attempt to force the hip back into place (Manipulation). This stretches the retinacular vessels -> AVN.
    • Accept the deformity. (The neck remodels over years).
  • Surgical Dislocation (Dunn Procedure):
    • Open surgery to realign the head.
    • High risk, specialised centres only. Used for severe slips.

The Contralateral Hip

  • Controversy: Should we pin the other side?
  • Pro: Prevents a future slip (substantial risk). Complication rate of prophylactic pinning is low.
  • Con: Overtreatment.
  • Consensus: Pin both if:
    • Endocrine cause.
    • Very young (<10).
    • Open Triradiate cartilage (lots of growth left).
    • Unreliable follow-up.
6. Complications

1. Avascular Necrosis (AVN)

  • The death of the femoral head.
  • Cause: Tearing of the lateral retinacular vessels during the slip or surgery.
  • Result: Hip collapse -> Early total hip replacement.

2. Chondrolysis

  • Rapid destruction of articular cartilage.
  • Cause: Screw penetrating the joint surface (recognized too late).
  • Result: Stiff, painful hip.

3. Femoro-Acetabular Impingement (FAI)

  • Even if healed, the "pistol grip" deformity of the neck can jam against the acetabulum later in life -> Early Arthritis.
7. Patient Explanation

"Your son has a condition called SUFE. It's like the ice cream ball of the hip joint has slipped off the cone. It is a serious condition because the blood supply to the ball is fragile. We need to perform surgery to put a screw across it, to stop it slipping further. We will not try to force it back straight, as that might damage the blood supply."

8. Glossary
  • Drehmann's Sign: Involuntary external rotation on flexion.
  • Frog-Lateral: X-ray View with hips abducted and flexed. (Looks like a frog).
  • Klein's Line: The line along the femoral neck.
  • Metaphysis: The neck bone.
  • Physis: The growth plate (The weak point).
  • Trethowan's Sign: Klein's line fails to intersect the head.
9. References
  1. Loder RT, et al. Acute slipped capital femoral epiphysis: the importance of physeal stability. J Bone Joint Surg Am. 1993.
  2. Klein A, et al. Slipped capital femoral epiphysis. Am J Roentgenol. 1951. (Original description of the line).
  3. Kocher MS, et al. Slipped capital femoral epiphysis. J Am Acad Orthop Surg. 2004.
13. Technical Appendix A: The Contralateral Hip Debate

"To pin or not to pin?" This is the biggest debate in paediatric orthopaedics.

The Statistics

  • Risk: If a child presents with a unilateral slip, the risk of the other hip slipping later is 20-80% (depends on follow-up length).
  • Timing: Most contralateral slips happen within 18 months.
  • The Silent Slip: Many slips are asymptomatic until seen on X-ray.

The Scoring System (Oxford)

Predictors of contralateral slip:

  1. Age: Younger children (<10) have more "growth time" remaining -> Higher risk.
  2. Endocrinopathy: 100% risk of bilateral slip eventually. Always pin.
  3. The Posterior Sloping Angle: Radiological measurement. If the unaffected hip has a steep posterior tilt (>14 degrees), it is mechanically primed to slip.

The Consensus (BOAST Guidelines)

  • Offer Prophylactic Pinning: To all patients. Discuss risks (infection, fracture) vs benefits (preventing severe deformity).
  • Strongly Recommend if:
    • Endocrine cause.
    • Radiation therapy history.
    • Unreliable family (won't come to follow-up).
14. Technical Appendix B: Advanced Biomechanics

1. The "Ice Cream Cone" Physics

  • Shear Stress: The physis (growth plate) is oblique. Weight bearing creates a shearing force attempting to slide the head off.
  • Resistance:
    • Perichondrial Ring: A fibrous band around the physis. (Thins out during puberty).
    • Mammillary Processes: Bumps on the physis that lock together. (Flatten out during growth spurt).
  • Why Obesity Matters: Increase Load + Oblique Angle = Shear Force > Resistance.

2. The Vascular Anatomy (Why AVN happens)

  • Lateral Epiphyseal Vessels: The main blood supply.
  • Course: They run along the posterior-superior neck in a retinacular fold (Weitbrecht).
  • The Limit: In a severe slip, the neck moves anteriorly, stretching these posterior vessels to their breaking point ("Kinking").
  • Emergency: Reducing the slip (forceful manipulation) kinks them further. This is why we accept the deformity.
15. Technical Appendix C: Detailed Case Studies

Case 1: The "Knee Pain" Miss (Medical Negligence)

  • Patient: 13M. Obese. Complain of Left Knee pain.
  • GP: Examined knee. Normal. Diagnosis: "Growing Pains".
  • 3 Months Later: Patient falls. Cannot walk.
  • X-ray: Severe, unstable SUFE.
  • Outcome: AVN. Total Hip Replacement at age 15.
  • Lesson: ALWAYS EXAMINE THE HIP IN KNEE PAIN. The obturator nerve supplies both.

Case 2: The "Unstable" Slip

  • Patient: 12F. Acute pain. Cannot weight bear.
  • Management:
    • Strict Bed Rest.
    • Urgent surgery (<24 hours).
    • Double Screw fixation? (To provide rotational stability).
    • Capsulotomy? (To release pressure - controversial).
  • Outcome: Healed without AVN.
16. Extended Glossary
  • Chondrolysis: Dissolution of cartilage. (Joint space narrowing).
  • Coxa Vara: Deformity where the neck-shaft angle is reduced (<120 degrees). Result of severe slip.
  • Epiphysiolysis: The pathological process of the slip.
  • Impingement: Abnormal contact between bones.
  • Osteotomy: Cutting bone to realign it. (Used for severe healed slips to fix mechanics).
  • Southwick Angle: Using the Lateral X-ray to measure the severity of the slip.
    • Mild: <30 deg.
    • Mod: 30-50 deg.
    • Severe: >50 deg.
17. Detailed Bibliography (Top 10)
  1. Loder RT. The demographics of slipped capital femoral epiphysis. An international multicenter study. Clin Orthop Relat Res. 1996.
  2. Klein A, et al. Roentgenographic features of slipped capital femoral epiphysis. Am J Roentgenol. 1951.
  3. Kocher MS, et al. The value of the frog-leg lateral radiograph in the diagnosis of slipped capital femoral epiphysis. J Pediatr Orthop. 2005.
  4. Sankar WN, et al. The unstable slipped capital femoral epiphysis: risk factors for osteonecrosis. J Pediatr Orthop. 2013.
  5. Carney BT, et al. Long-term follow-up of slipped capital femoral epiphysis. J Bone Joint Surg Am. 1991.
  6. Goyal N. The Vascular Anatomy of the Adolescent Hip. Paediatric Orthopaedics. 2023.
  7. British Orthopaedic Association (BOAST). The Management of SUFE. 2020.
  8. NICE CKS. Limp in Children. 2022.
  9. Millis MB. Slipped capital femoral epiphysis: an instructional course lecture. J Bone Joint Surg. 2011.
  10. Fahey JJ, O'Brien ET. Acute slipped capital femoral epiphysis. J Bone Joint Surg Am. 1965.

(End of File)

Last updated: 2025-12-25

At a Glance

EvidenceHigh
Last Updated2025-12-25
Emergency Protocol

Red Flags

  • Unstable Slip (Inability to weight bear - High AVN risk)
  • Atypical Age (&lt;10 or &gt;16 - endocrine screen)
  • Knee pain (Hip pathology until proven otherwise)

Clinical Pearls

  • **Medical Disclaimer**: SUFE is an orthopaedic emergency. Unstable slips have a 50% risk of AVN. Do not allow the patient to walk. Wheelchair only.
  • ## 1. Clinical Overview
  • Early total hip replacement.

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines