Orthopaedic Surgery - Slipped Capital Femoral Epiphysis

Basics

Slipped capital femoral epiphysis, or:

SCFE

is an adolescent hip disorder in which the:

Femoral head remains seated within the acetabulum

while the:

Femoral neck and metaphysis displace relative to the epiphysis through the proximal femoral physis.

Clinically, this produces:

External rotation of the lower extremity

and often a:

Limp.

Classification

SCFE can be classified according to:

Stability

Duration of symptoms

and

Degree of displacement.

Stable SCFE

A slip is considered:

Stable

when the patient can still bear some weight on the affected limb, with or without:

Crutches.

Stable slips have a substantially better prognosis.

Historical series report satisfactory results in approximately:

95% of appropriately treated stable cases.

Unstable SCFE

A slip is:

Unstable

when the patient is unable to bear weight, even with assistance.

This form carries a much higher risk of:

Avascular necrosis

and often represents a more severe:

Physeal injury.

Historical series have reported satisfactory outcomes in only about:

50% of unstable cases.

Chronologic Classification

SCFE may also be categorized by symptom duration.

Acute: symptoms present for less than approximately 3 weeks

Chronic: symptoms present for more than approximately 3 weeks

Some patients have an:

Acute-on-chronic presentation

with sudden worsening of longstanding symptoms.

Anatomic Severity

Displacement can be graded by the percentage of slip.

Grade 0 – Preslip: no visible displacement, but clinical or MRI evidence of impending physeal failure

Grade I – Mild: approximately 1–33% displacement

Grade II – Moderate: approximately 33–50% displacement

Grade III – Severe: more than 50% displacement

Epidemiology

SCFE occurs predominantly during the:

Adolescent growth spurt.

Approximately:

80% of cases

occur during adolescence.

Typical Age

The usual age range is approximately:

10–16 years in boys

and

9–14 years in girls.

Sex

Boys are affected more often than girls, historically at approximately a:

2.4:1 male-to-female ratio.

Incidence

The incidence in the general population has been reported at approximately:

2–10 cases per 100,000 persons per year.

Seasonal Variation

Historical studies have suggested seasonal variation, with higher incidence around:

September

and lower incidence around:

March.

Possible explanations have included:

Seasonal activity patterns

and potential effects of:

Vitamin D status, although the clinical significance remains uncertain.

Risk Factors

Important risk factors include:

Adolescence

Male sex

Obesity

Delayed skeletal maturation

and

Previous contralateral SCFE.

Obesity

Obesity is one of the strongest risk factors.

Approximately:

50–75% of patients

have historically had a BMI above the:

90th percentile.

Bilateral Disease

SCFE may affect both hips.

Approximately:

25%

have bilateral disease at initial presentation, and up to approximately:

50%

may eventually develop involvement of the:

Contralateral hip.

Race and Population Variation

Incidence differs among populations.

Historically, higher rates have been reported in:

Black adolescents

compared with some other groups.

Genetics

Familial clustering occurs more often than expected by chance.

Historical reports suggest SCFE in approximately:

5–7% of family members

of affected patients.

However, most cases do not follow a simple:

Mendelian inheritance pattern.

Etiology

SCFE is most likely:

Multifactorial.

The proximal femoral growth plate becomes susceptible when:

Physeal strength decreases

while

Shear forces increase.

Growth-Plate Vulnerability

During rapid growth, the proximal femoral physis becomes relatively:

Weaker

and more vulnerable to:

Shear stress.

Mechanical Stress

Increased mechanical stress may result from:

Obesity

Activity

Minor trauma

or altered:

Hip biomechanics.

Endocrine and Metabolic Causes

Less commonly, SCFE may be associated with disorders that weaken the:

Physis.

Examples include:

Hypothyroidism

Panhypopituitarism

Hypogonadism

Hyperparathyroidism

Renal osteodystrophy

and

Chronic renal failure.

Radiation

Previous:

Pelvic radiation therapy

may also weaken the proximal femoral physis and predispose to:

SCFE.

Associated Conditions

Important associated conditions include:

Hypothyroidism

Hyperparathyroidism

Chronic renal disease

Renal osteodystrophy

and

Previous pelvic irradiation.

Diagnosis

Diagnosis requires a high index of suspicion because symptoms are often:

Mild

Insidious

or referred away from the hip.

Signs and Symptoms

The most common symptom is:

Pain.

Pain Location

Pain may be located in the:

Groin

Medial thigh

or

Knee.

Referred Knee Pain

Some patients present almost entirely with:

Knee pain.

This is an important cause of delayed diagnosis.

A child or adolescent with unexplained knee pain should therefore have the:

Hip examined.

Limp

Common gait abnormalities include:

Antalgic gait

Trendelenburg gait

and

Externally rotated gait.

Antalgic Gait

The patient spends as little time as possible bearing weight on the:

Affected limb.

External Rotation

The affected lower extremity often rests in:

External rotation.

History

SCFE frequently develops without a major traumatic event.

The onset is often:

Spontaneous and gradual.

Trauma

Some patients report:

Minor trauma

but this is not required for diagnosis.

Delayed Presentation

Pain may be relatively mild, and patients may delay seeking medical attention.

Some report only:

Fatigue

Limping

or difficulty keeping up with peers.

Endocrine Symptoms

Features suggesting an associated endocrine disorder include:

Cold intolerance

Lethargy

Delayed skeletal maturity

Coarse hair

and abnormalities of:

Growth or puberty.

Physical Examination

Groin and Proximal Femur Tenderness

There may be mild tenderness over the:

Groin

or

Proximal femur.

Internal Rotation

Loss of:

Hip internal rotation

is one of the most characteristic examination findings.

Many patients have:

Little or no internal rotation.

Painful Motion

Pain is typically greatest with:

Internal rotation

and sometimes:

Abduction.

Obligatory External Rotation

A classic finding is:

Obligatory external rotation during hip flexion.

As the hip is flexed, the leg automatically rotates:

Externally.

This is sometimes called:

Drehmann sign.

Resting Position

The affected limb often rests in more:

External rotation

than the opposite side.

Endocrine Screening

History and examination should assess for evidence of:

Hypothyroidism

Pituitary disease

Hypogonadism

and

Renal osteodystrophy.

Laboratory Tests

Routine laboratory testing is not required in every patient.

Endocrine Evaluation

An endocrine workup is appropriate when there is:

Marked delay in skeletal maturity

Atypical age

Short stature

or symptoms suggesting:

Endocrine or metabolic disease.

Imaging

Plain Radiographs

Standard radiographs are usually sufficient to establish the diagnosis.

Typical views include:

AP pelvis

and

Lateral view of the affected hip.

Lateral View

The slip is often most apparent on the:

Lateral projection.

Frog-Leg Lateral

A frog-leg lateral may be useful in a:

Stable SCFE.

It should generally be avoided in an unstable slip because positioning may theoretically worsen:

Displacement.

A cross-table lateral can be used instead.

Radiographic Appearance

The epiphysis remains in the acetabulum while the metaphysis and femoral neck move:

Anteriorly and superiorly

relative to the head.

This produces the classic appearance of:

Ice cream slipping off its cone.

Kline Line

Kline line is drawn along the superior border of the:

Femoral neck.

Normally, this line should intersect part of the:

Femoral head epiphysis.

Loss or reduction of this intersection suggests:

SCFE.

Physeal Changes

Other radiographic findings include:

Widening of the physis

Physeal lucency

Physeal irregularity

and

Blurring of the growth plate.

Epiphyseal Height

There may be a relative decrease in:

Epiphyseal height

compared with the:

Contralateral hip.

Varus Relationship

The epiphysis may appear relatively:

Varus

with respect to the femoral neck.

Pistol-Grip Deformity

Chronic remodeling can produce a:

Pistol-grip deformity

from prominence of the:

Anterolateral femoral neck or metaphysis.

This can predispose to:

Femoroacetabular impingement.

MRI

MRI is useful when a:

Preslip

is suspected despite normal or equivocal radiographs.

Preslip MRI Findings

MRI may show:

Physeal widening

and

Bone marrow edema adjacent to the physis.

These findings can precede visible displacement.

CT

CT may define:

Severe deformity

or help with complex preoperative planning, but is not routinely required for straightforward diagnosis.

Differential Diagnosis

Important alternatives include:

Perthes disease

Proximal femoral fracture

Femoral neck stress fracture

Transient synovitis

Septic arthritis

and other causes of adolescent:

Hip or knee pain.

Perthes Disease

Perthes disease typically affects younger children, often approximately:

4–8 years old.

It may present with:

Limp

and relatively mild pain.

Radiographs distinguish it from:

SCFE.

Proximal Femoral Fracture

True proximal femoral fractures in children and adolescents are usually associated with:

High-energy trauma.

Femoral Neck Stress Fracture

Femoral neck stress fractures are more common near or after:

Skeletal maturity.

They occur more distally along the:

Femoral neck

rather than through the physis.

Treatment

General Principles

Once SCFE is suspected or diagnosed:

Weight bearing should stop immediately.

The central goal is to:

Prevent additional displacement.

Initial Management

The patient should be placed on:

Strict non-weight-bearing precautions

and referred urgently for:

Orthopaedic surgical management.

Admission

Many patients are admitted for:

Prompt operative stabilization.

In Situ Fixation

The standard treatment for most stable slips is:

Percutaneous in situ screw fixation.

Goal of Fixation

The purpose is to:

Prevent further slipping

and allow the:

Physis to close.

Surgical Technique

A guidewire is placed percutaneously from the:

Anterior or anterolateral femoral neck

into the center of the:

Femoral epiphysis.

Cannulated Screw

A cannulated screw, historically approximately:

6.5–7.3 mm

is advanced over the guidewire.

Screw Position

The screw should achieve secure fixation while avoiding penetration of the:

Subchondral articular surface.

Joint Penetration

Screw penetration into the:

Hip joint

can damage cartilage and increase the risk of:

Chondrolysis.

Number of Screws

For most stable SCFE cases, a:

Single centrally positioned screw

is typically sufficient.

Unstable or Severe SCFE

Management of unstable severe slips is more controversial because of the high risk of:

Osteonecrosis.

Reduction

Some surgeons use:

Gentle positioning

or cautious reduction.

Forceful manipulation should be avoided because it may further damage the:

Retinacular blood supply.

Modified Dunn Procedure

In selected severe slips, an open realignment procedure such as the:

Modified Dunn procedure

may be considered by experienced surgeons.

This permits correction while directly protecting the:

Femoral head blood supply.

Corrective Osteotomy

Residual severe deformity may sometimes be treated with:

Proximal femoral osteotomy

to improve:

Alignment

and

Hip mechanics.

Contralateral Prophylactic Fixation

Prophylactic fixation of the opposite hip remains:

Selective rather than routine.

Possible Indications

It may be considered in:

Very young patients

Endocrine or metabolic disorders

Renal disease

Marked skeletal immaturity

or situations in which reliable:

Follow-up is uncertain.

Screw Removal

Routine screw removal after successful fixation is generally:

Not recommended.

Physical Therapy

After surgery, patients require instruction in:

Crutch or walker use.

Weight Bearing

Patients with stable slips may progress to:

Partial weight bearing

according to the surgeon’s protocol and evidence of:

Healing and stability.

Rehabilitation

Physical therapy may address:

Gait

Hip motion

Strength

and safe progression of:

Weight bearing.

Late Degenerative Disease

Patients who later develop severe hip degeneration may require:

Reconstructive procedures.

Historically these have included:

Hip fusion in selected young patients

or

Total hip arthroplasty in adults.

Follow-Up

Long-term follow-up is important because of the risk of:

Contralateral SCFE

and later:

Hip degeneration.

Contralateral Hip Monitoring

The opposite hip should be monitored clinically and radiographically when appropriate, particularly in patients with:

High bilateral risk.

Prognosis

Outcome depends primarily on:

Slip severity

Stability

and presence of:

Complications.

Stable Slips

Stable slips generally have a:

Favorable prognosis

when treated promptly.

Unstable Slips

Unstable slips have a much worse prognosis because of the greater risk of:

Femoral head osteonecrosis.

Degenerative Joint Disease

Even without major early complications, altered proximal femoral shape may predispose to:

Early degenerative joint disease.

Weight Management

Weight reduction in patients with obesity may decrease:

Mechanical load

on the hip and improve long-term:

Joint health.

Metabolic Health

Patients with SCFE and obesity may also have increased risk of:

Type 2 diabetes

Hypertension

and other obesity-related conditions.

Complications

Osteonecrosis

Osteonecrosis is one of the most serious complications.

It results from loss of blood supply to the:

Femoral head.

Consequences of Osteonecrosis

The femoral head may:

Collapse

leading to:

Severe pain

Stiffness

and

Early degenerative arthritis.

Risk of Osteonecrosis

Risk is greatest in:

Unstable SCFE.

Historical estimates have reported rates approaching:

40% in unstable slips

compared with approximately:

5% in stable slips.

Chondrolysis

Chondrolysis is:

Rapid loss of articular cartilage

leading to:

Pain

Joint-space narrowing

and

Hip stiffness.

Causes of Chondrolysis

Potential contributors include:

Severe disease

Inflammation

and especially:

Intra-articular hardware penetration.

Femoroacetabular Impingement

After SCFE, the metaphysis may remain relatively prominent and anterior to the:

Femoral head.

During hip flexion and internal rotation, this prominence can contact the:

Acetabular rim.

Consequences of Impingement

This may produce:

Pain

Labral damage

Cartilage injury

and progressive:

Femoroacetabular impingement.

Treatment of Residual Impingement

Selected patients may be treated with:

Osteoplasty

or

Corrective osteotomy

depending on deformity severity.

Degenerative Joint Disease

Untreated or severely deformed SCFE may result in:

Early osteoarthritis

and can eventually lead to:

Total hip arthroplasty.

Patient Monitoring

Follow-up should assess:

Pain

Gait

Hip range of motion

Radiographic healing

Slip progression

and the status of the:

Contralateral hip.

Key Principle

Slipped capital femoral epiphysis is an adolescent disorder in which the femoral neck and metaphysis displace relative to the femoral head through a weakened proximal femoral growth plate.

The most important clinical clues are:

Limp, loss of internal rotation, obligatory external rotation with hip flexion, and groin, thigh, or referred knee pain.

Once suspected:

Weight bearing should stop immediately, and urgent orthopaedic assessment is required.

Most stable slips are treated with:

Percutaneous in situ screw fixation to prevent further displacement and promote physeal closure.

The most serious complications are:

Osteonecrosis, chondrolysis, femoroacetabular impingement, and premature degenerative arthritis, with unstable slips carrying the highest risk of poor outcome.