Pediatric Forearm Fractures

J.J. Prosser

Incidence

• 3.4% of all children’s fractures

• Bimodal peak with boys – 9 and 13 years old

• Girls – 5 years old

0ssification

Radial and ulnar shafts ossify during the eighth week of gestation

Distal radial epiphysis – age 1

Distal ulnar epiphysis – age 6

Radial head – age 5-7

Olecranon – age 9-10

They all close between the ages of 16-18

Anatomic Area

Distal third – 75%

Middle third – 18%

Proximal third – 7%

Osteology

The periosteum is very strong and thick in a child

It is generally disrupted on the convex side, while an intact hinge remains on the concave side

This is an important point when considering closed reduction

Biomechanics

The radius shortens with pronation and lengthens with supination

Malreduction of 10 degrees in the middle third limits rotation by 20-30 degrees

Bayonet apposition does not reduce forearm rotation

Deforming Muscle Forces

Proximal third Biceps and supinator – flexion and supination of proximal

fragmentPronator teres and quadratus – pronate distal fragment

Middle thirdSupinator, biceps, and pronator teres – proximal fragment is

neutralPronator quadratus – pronates distal fragment

Distal thirdBrachioradialis – dorsiflex and radial deviate distal

fragment

Mechanism of injury

Indirect – fall onto an outstretched hand

Direct – blow from an object onto the radial and ulnar shaft

Rotation Pronation – flexion injury(posterior angulation)

Supination – extension injury(anterior angulation)

Clinical evaluation

History – age, mechanism of injury, and other areas of pain

Physical exam – skin integrity, neurovascular status, and examination of elbow and wrist joints

Radiographic evaluation

AP and lateral of forearm, wrist, and elbow

The bicipital tuberosity is the landmark for identifying rotation

Description

Location – proximal, middle, distal

Type Plastic deformation

Incomplete(greenstick)

Compression(torus or buckle)

Complete

Salter-Harris

75% in children 10-16 years old

Uncommon in children < 5 years old

Type II most common – Thurston-Holland fragment

Monteggia

Proximal ulna fracture with dislocation of the radial head0.4% of all forearm fractures in children

Peak incidence between 4 and 10 years old

Ulna fracture usually at junction of proximal/middle thirds

Galeazzi

Middle to distal third radius fracture with disruption of the distal radioulnar jointRare in children

Peak incidence between 9 and 12 years old

Initial management

Correct gross deformityPerform closed reduction and application of a well

molded long arm castForearm reduction after rotation

Proximal third – supinationMiddle third – neutralDistal third – pronation

Split cast if concerned about swelling(uni-valve, bi-valve)

Acceptable deformity

Patients > 10 years old, treat like adult – no deformity accepted

Patients < 10 years old;Angular deformities – 1 degree/month

- 10 degrees/year

Rotational deformities – none

Bayonet apposition – 1cm

Undisplaced fractures

Long arm cast – 4-6 weeks until nontender

Elbow at 110-120 degrees of flexion

Plastic deformation

Children < 4 years old or with deformities < 20 degrees, same as undisplaced

Greenstick fractures

Complete the fracture to decrease risk of angular deformity

Carefully crack the intact cortex while preventing displacement

Well molded long arm cast

Complete displacement

Attempt closed reduction and long arm cast with pancake molding

If the fracture is irreducible, ORIF may be indicated

Operative management

IM fixation – Enders nail, K-wires

- limited exposure at fracture site may be required for reduction

Plate fixation – prime indication is one of refracture in which the intramedullary canal has a high risk of being obstructed

Problems

Malunion – over 60% have rotational losses >20 degrees

Refracture – incidence of 12% - refrain from sports 1 month after cast

removalNonunion – rare in children - high energy, open, infection - ulnar > radialNeurovascular injuries – posterior interosseous nerve

damage with Monteggia Type III

Problems continued

Compartment syndrome – pain aggravated by passive motion - pressure > 30mmHg - fasciotomyInfection - > 6 hours before debridement(exponential growth)RSD – rare in children - burning pain, hyperesthesia, and swelling - resolves 6-12 months after injuryOvergrowth – 6-8 months after injury - averages 6-7mm