Epidemiology

Incidence between 0.2-10/100 000
M>F 60%:40%
Mean age of diagnosis 13.5 in boys, 12 in girls
Obesity can lead to earlier age of presentation
18-50% of cases can be bilateral
- Of the unilateral cases that go on to develop contralateral SUFE, second slip usually occurs within 18 months of the first

Aetiology

Mechanical factors
- Obesity–> increased shear stress across the physis (obesity is associated with decreased femoral anteversion)
- Femoral Retroversion
- Increased physeal obliquity

Rapid longitudinal growth during puberty due to increased levels of growth hormone
Rapid growth associated with increased chondrocyte proliferation and increased height of zone of hypertrophy. Increased height may contribute to decreased physeal strength
Oestrogen reduces physeal height and increases physeal strength while testosterone reduces physeal strength–> May explain increased incidence in males

Traditional (temporal) classification

Type	Presentation	Examination
Pre-slip	Lower limb weakness, limp and exertional groin, hip or knee pain. AP pelvis and frog leg lateral may show disuse osteopenia	Reduced internal rotation and guarding
Acute (10 to 15%)	Under 3 weeks, usually too painful to weight bear. Most have 1 to 3 months of prodromal knee, hip or thigh pain or limp	External rotation deformity, shortening and painful restricted motion
Chronic (about 85%)	Groin or thigh pain with a limp, with exacerbations and remissions over months to years	Antalgic gait, loss of internal rotation, abduction and flexion
Acute on chronic	Acute worsening of a chronic slip	As for an acute slip

Loder classification (physeal stability)

Type	Definition	Osteonecrosis
Stable	Can weight bear, with or without crutches	Almost 0%
Unstable	Unable to weight bear, pain limits any attempt to move the limb	Up to 50%

Stable SUFE
- In situ fixation
  - Single Screw fixation- Most accepted treatment
    - Advantage: Percutaneous placement with minimal soft tissue trauma. High success rate, low incidence of slip progression, osteonecrosis and chondrolysis
  - Multiple screw/pin fixation
    - Higher rate of unrecognised screw penetration compared to single screw
- Bone graft Epiphysiodesis
  - Avoid complications associated with internal pin fixation inc unrecognized pin penetration and damage to lateral epiphyseal vessels, although larger scar and increased blood loss and surgical time compared to in situ fixation
- Hip Spica Cast
  - Immobilisation in bilateral hip spica avoids complications associated with surgical management. Risk of pressure sores, chondrolysis and further slip
Unstable SUFE
- Risk of osteonecrosis higher than stable SUFE
- Consider urgent hip joint haematoma aspiration, closed reduction and single screw fixation
- Followed by 6-8/52 non-weightbearing
Prophylactic fixation of contralateral side
- Risk of contralateral side becoming affected reported as 2335 times higher than the risk of the initial SUFE

Osteonecrosis; increased with unstable SUFE, over-reduction, attempted reduction of stable SUFE, pin placement in the posterosuperior quadrant and cuneiform osteotomy
Chondrolysis- usually secondary to unrecognised pin penetrations through the femoral head

Reference: Aronsson et al ‘Slipped Capital Femoral Epiphysis: Current Concepts’. J Am Acad Orthop Surg 2006; 14:666-679

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.