Slipped Upper Femoral Epiphysis (SUFE), also known as Slipped Capital Femoral Epiphysis (SCFE), is an acute or chronic displacement of the proximal femoral epiphysis through the growth plate. The femoral head slips in a posteromedial direction relative to the femoral neck.

SUFE is a surgical emergency requiring urgent orthopedic intervention. Delay in diagnosis and treatment significantly increases morbidity, including avascular necrosis and chondrolysis. Incidence is approximately 2 per 100,000 children, with bilateral involvement in 20-40% of cases.

SUFE results from instability of the growth plate due to:

• Endocrine risk factors: Hypothyroidism, growth hormone deficiency, hypogonadism, diabetes mellitus, panhypopituitarism
• Metabolic bone disease: Renal osteodystrophy, hypophosphatemic rickets
• Obesity: Major risk factor; associated with metabolic and mechanical factors leading to physeal weakness
• Rapid growth: Adolescent growth spurt creates mechanical stress on growth plate
• Genetic factors: Familial clustering reported; increased risk in first-degree relatives
• Mechanical factors: Hip varus, retroversion, increased femoral anteversion

Two clinical presentations:

• Acute SUFE: Sudden onset with acute trauma; severe pain; inability to weight-bear
• Chronic SUFE: Insidious onset over weeks to months; mild symptoms; positive Drehmann sign

Acute slips on chronic slips (acute-on-chronic) represent acute decompensation of previously asymptomatic chronic slip — particularly high-risk for complications.

Classic presenting complaint: Groin, hip, thigh, or knee pain (often referred to knee) with limp in adolescent, frequently obese.

Physical examination findings:

• Gait: Antalgic limp or inability to bear weight
• Hip position: Hip held in flexion and external rotation
• Range of motion: Severe loss of internal rotation; hip flexion contracture
• Drehmann sign: POSITIVE — when hip is flexed passively, it obligatorily externally rotates (pathognomonic sign)
• Trendelenburg sign: Positive; indicates hip muscle weakness
• No systemic symptoms: Absence of fever distinguishes from infection

Important: SUFE must be distinguished from:

• Septic arthritis (fever, elevated inflammatory markers, toxic appearance)
• Femoral shaft fracture (history of significant trauma, very acute onset)
• Developmental dysplasia (diagnosed in infancy, different age group)

Plain Radiography (First-line, required before any other intervention):

• Anteroposterior (AP) view of pelvis: shows posteromedial femoral head displacement relative to femoral neck
• Frog-lateral view (internal rotation): mandatory — sensitivity much higher than AP alone. Shows slip clearly
• Klein's line: On AP view, draw line along superior femoral neck margin. Normal femoral head intersects this line; in SUFE, femoral head lies below the line (pathognomonic)
• Bilateral films essential — 20-40% bilateral involvement; contralateral hip may show early asymptomatic slip

Magnetic Resonance Imaging (MRI):

• Excellent for detecting pre-slip changes in contralateral hip
• Shows marrow edema and physeal widening before radiographic changes
• Not required for diagnosis but useful for prophylactic evaluation

Laboratory tests: Check for endocrine abnormalities:

• Thyroid function tests (TSH, free T4)
• Growth hormone assessment if indicated by growth history
• Fasting glucose, metabolic markers
• ESR/CRP — normal; elevated suggests infection rather than SUFE

Severity also classified by degree of slip:

• Mild: <50% epiphyseal width displaced
• Moderate: 50-99% displacement
• Severe: >100% displacement (femoral head slips beyond opposite femoral neck margin)

Immediate management:

• Non-weight-bearing status: Immediate cessation of weight-bearing to prevent acute-on-chronic conversion and reduce AVN risk
• Orthopedic referral: Emergent referral to orthopedic surgery. Do NOT send child home or to ED observation
• Imaging: AP and frog-lateral radiographs mandatory before surgery; bilateral films to assess contralateral hip
• Avoid manipulation: Forceful reduction increases AVN risk

Surgical treatment:

• Stable SUFE: Percutaneous in-situ pinning with single cannulated screw. Gold standard. Performed within 24-48 hours
• Unstable SUFE: Emergency in-situ pinning. Perform within 6-12 hours when possible. Extensive preoperative AVN risk
• Severe slip with complications: May require open reduction and internal fixation or subtrochanteric derotation osteotomy if significant deformity develops

Contralateral hip prophylaxis (Controversial):

• 15-25% risk of SUFE in asymptomatic contralateral hip
• Prophylactic pinning vs. observation: varies by surgeon and institution
• MRI can identify pre-slip changes to guide prophylaxis decision
• Close radiographic monitoring (X-rays every 4-6 weeks) if observation chosen

Note: SUFE is a surgical condition. Medical therapy is perioperative analgesia only.

Diagnostic algorithm:

• Take weight-bearing history: can child ambulate? Can child weight-bear on affected side?
• Check for Drehmann sign (obligate external rotation with hip flexion) — highly specific for SUFE
• Obtain STAT AP and frog-lateral pelvis radiographs (bilateral) if SUFE suspected
• Review Klein's line on AP view — is femoral head below the line?
• Contact orthopedic surgery immediately if diagnosis confirmed or highly suspected

Do NOT:

• Allow weight-bearing (increases slip and AVN risk)
• Perform hip manipulations or aggressive range of motion testing
• Delay surgical referral for additional imaging
• Discharge home pending orthopedic appointment
• Assume this is "growing pain" or soft tissue injury

Endocrine screening: Check thyroid function (TSH), growth hormone status, fasting glucose, metabolic markers. Many SUFE patients have underlying endocrine abnormalities requiring treatment.

Post-operative monitoring:

• Pain trajectory: Pain should improve post-operatively; persistent or increasing pain suggests AVN or infection
• Limb perfusion: Monitor for calf swelling, cyanosis, coolness suggesting DVT or vascular compromise
• Radiographs: Assess screw position, degree of slip correction. Additional imaging (CT, MRI) if AVN suspected
• Hip range of motion: Gradual improvement in internal rotation and abduction; contractures should resolve
• Contralateral hip assessment: Radiographs every 4-6 weeks if observation chosen; immediate imaging if symptoms develop

Obese adolescents: Markedly increased risk of SUFE. Metabolic syndrome, insulin resistance, and endocrine abnormalities common. Requires aggressive weight management post-operatively and endocrine assessment.

Endocrine disorders: Hypothyroidism, growth hormone deficiency, hypogonadism, diabetes all increase SUFE risk. Requires endocrine specialist input for hormone replacement or thyroid management.

Renal disease: Secondary hyperparathyroidism and renal osteodystrophy increase SUFE risk. Requires close collaboration with nephrology for mineral metabolism management.

Bilateral SUFE (20-40% of cases): Usually sequential presentation; contralateral hip may be asymptomatic but at risk. Prophylactic pinning vs. serial monitoring decision made by orthopedic surgeon. Excellent outcome if bilateral slips treated appropriately.

Diagnostic stewardship: Plain radiography (AP and frog-lateral) is diagnostic and sufficient. MRI reserved for contralateral hip assessment or complications. CT not needed for uncomplicated SUFE. Avoid delays in diagnosis for advanced imaging.

Surgical stewardship: In-situ pinning is gold standard; simple, effective, single-stage procedure. Reserve open reduction and osteotomy for severe slips or failed in-situ fixation. Avoid aggressive reduction techniques that increase AVN risk.

Medication stewardship: Paracetamol is first-line perioperative analgesia. NSAIDs used cautiously and briefly post-operatively only. Avoid prolonged use post-operatively; healing prioritized over analgesia.

Endocrine stewardship: Screen all SUFE patients for underlying endocrine abnormalities. Refer to endocrinology for identified disorders. Address metabolic risk factors (obesity, insulin resistance) to reduce contralateral SUFE risk.

Immediate post-operative outcomes: Most children recover well after in-situ pinning. Pain resolves over 2-4 weeks. Weight-bearing progresses to full capacity by 8-12 weeks.

Major complications and their incidence:

• Avascular Necrosis (AVN): 0-5% in stable slips; up to 20-40% in unstable slips. Risk highest with unstable presentation or delayed fixation. AVN may be clinically silent initially
• Chondrolysis: Arthritis and joint space narrowing; can occur post-operatively even with appropriate surgery. Incidence 5-10%
• Contralateral SUFE: 20-40% bilateral involvement; may occur weeks to years later
• Early osteoarthritis: Can develop in adolescence/early adulthood, particularly with residual deformity or AVN

Long-term functional outcomes: With appropriate prompt surgical fixation, most adolescents return to normal activities including sports. Severe complications (AVN, chondrolysis) may limit activities and require activity modification into adulthood.

Contralateral hip surveillance: If prophylactic pinning not performed, patient requires radiographic monitoring (every 4-6 weeks for 1 year, then 6-monthly) for development of slip. Any symptoms warrant immediate radiographs.

Transition to adulthood: SUFE patients entering adulthood require transition to adult orthopedic care. Discuss long-term hip health, impact of obesity and metabolic factors, hip OA risk factors, and sport/activity limitations if any.

Prevention in future generations: Counsel on modifiable risk factors (obesity, metabolic syndrome) for their own children. Screen first-degree relatives if endocrine conditions identified.

• American Academy of Orthopaedic Surgeons (AAOS): Guidelines on Slipped Capital Femoral Epiphysis
• Pediatric Orthopedic Society of North America (POSNA): SCFE diagnosis and management standards
• International Hip Dysplasia Institute: Evidence-based SCFE treatment recommendations
• Australian Orthopaedic Association: SUFE emergency management and surgical protocols
• eTG - Therapeutic Guidelines: Slipped upper femoral epiphysis in adolescents