Salter Harris Fracture

Salter Harris fractures are fractures involving the growth plate (physis) in a child, classified into five types by the path of the fracture line, and they carry a risk of growth disturbance.

• The physis is the weakest part of the immature skeleton, weaker than the surrounding ligaments.
• They make up about 15 to 30 percent of childhood fractures. The distal radius, distal tibia and fibula, and phalanges are the commonest sites.
• Type I: fracture through the physis only. Type II: through the physis and metaphysis (the commonest, about 75 percent). Type III: through the physis and epiphysis into the joint. Type IV: across the metaphysis, physis and epiphysis. Type V: crush injury to the physis, often found only in retrospect.
• Higher types (III, IV, V) have a higher risk of premature physeal closure, angular deformity and limb length discrepancy.
• Peak incidence is in early adolescence in boys.

Findings follow trauma near a joint.

• Pain, swelling and tenderness over the physis, with reluctance to bear weight or use the limb.
• Deformity if displaced; neurovascular compromise in displaced injuries.
• Tenderness over the physis with normal X-ray suggests type I or an occult injury.
• Joint effusion in intra-articular (type III and IV) fractures.
• Differential diagnosis: ligament sprain, metaphyseal fracture, osteomyelitis, septic arthritis, slipped capital femoral epiphysis, avulsion fracture, torus fracture and non-accidental injury.
• Complications: premature physeal closure, growth arrest, angular deformity, limb length discrepancy, joint incongruity and early osteoarthritis, avascular necrosis (femoral head, radial head), non-union, compartment syndrome and neurovascular injury.

Diagnosis is by X-ray, and a high index of suspicion is needed.

• Two orthogonal views of the affected bone including adjacent joints; add oblique views for the ankle and wrist.
• Radiographs may show widening of the physis, metaphyseal fragment (the Thurston Holland fragment in type II), or epiphyseal fracture.
• Comparison views of the opposite side if uncertain.
• Computed tomography to define intra-articular fractures and plan surgery. MRI to assess physeal injury or bone bridges.
• Ultrasound for occult type I injuries in young children.
• Tenderness over the physis with normal X-ray: presume a type I fracture, immobilise and repeat X-ray in 7 to 10 days.

Treatment depends on the type, displacement and site.

• Supportive: analgesia, elevation, splintage, and neurovascular observation.
• Pharmacological: paracetamol 15 mg/kg every 6 hours and ibuprofen 5 to 10 mg/kg every 8 hours. Oral morphine 0.1 to 0.2 mg/kg for severe pain. Sedation for reduction with ketamine 1 mg/kg intravenously or nitrous oxide 50 percent.
• Types I and II undisplaced: cast immobilisation for 3 to 6 weeks.
• Displaced types I and II: gentle closed reduction under sedation (one gentle attempt only, because repeated forceful attempts damage the physis), then cast.
• Types III and IV: anatomic reduction is needed, usually with open reduction and internal fixation (smooth pins or screws that avoid crossing the physis).
• Type V: protected weight bearing, with surveillance for growth arrest.
• Procedures: surgical bar resection or corrective osteotomy for growth arrest or deformity.
• Special groups: children close to skeletal maturity have less risk of deformity. Distal femoral and proximal tibial physeal fractures have a high rate of growth arrest and neurovascular injury.
• Red flags: open fracture, vascular compromise, compartment syndrome, intra-articular displacement, type III to V injuries, distal femoral physeal fracture and suspected abuse.
• Follow-up: X-ray at 1 to 2 weeks to detect displacement. Review growth at 6 months, 1 year and up to 2 years (Harris growth arrest lines, leg length measurement), as arrest may appear late.