Etiology
Peak age: 6 years
17% of all pediatric distal humerus fractures
2nd most common elbow fracture in children
Mechanism of Injury
Varus stress on a supinated forearm: supination puts supinator muscle on stretch causing avulsion mechanism
"Push vs. Pull": the former is an axial load transmitted through forearm / radial head / into capitellum and lateral condyle, "pushing" fragment off distal humerus
Milch Classification
Type I: fracture line extends from lateral condyle through capitulotrochlear groove
Stable elbow: trochlea intact
Salter-Harris IV
Less common type
Milch Classification
Type II: fracture line extends from lateral condyle through apex of trochlea
Unstable elbow
Salter-Harris II
More common type
Jakob Classification
Stage I: nondisplaced (<2mm), articular surface intact
Stage II: 2-4mm "hinged" displacement of metaphyseal fragment, articular surface intact
Stage III: completely displaced, distal fragment rotated; unstable elbow joint
Horn et al JPO 2002: "integrity of the cartilage hinge at the distal humeral epiphysis determines stability". Only metaphyseal component of lateral condyle fractures visualized on x-ray
Nonoperative Treatment
Jakob Stage I
Long arm cast with 90° elbow flexion, neutral forearm
Follow up with x-rays 2-3 times in first 3 weeks
D/C cast in 4 weeks
Finnobogason et al JPO 1995 followed 112 stage I lateral condyle fractures and found that fractures which did not extend into the elbow joint were stable and not at risk for displacement.
Jakob Stage II or III:
OR, Flouroscopy and/or arthrography to determine nature of fracture
Stage II: CRPP
Stage III: ORPP
CRPP Technique:
Two smooth 0.062 K-wires inserted into lateral condyle
Pins diverge in metaphysis
Range elbow, varus and valgus stress
Open technique:
Incision: anterior to lateral condylar ridge
Traumatic "rent" in extensor mass: enlarge traumatic opening to visualize fragment
DO NOT strip posterior aspect of fragment
Pin as mentioned above
Complications:
Overgrowth: 40% of lateral condyle fractures
Lateral spur: 28% of lateral condyle fractures
coronal rotation of distal fragment laterally displaces a periosteal flap on distal fragment
long-standing varus deformity associated with posterolateral instability of the elbow
Cubitus Valgus
Lateral physeal growth arrest
Delayed (>12 weeks) or Nonunion
More common in non operative treatment
Fishtail Deformity: persistent gap between lateral condyle and trochlea physes
Osteonecrosis:
Late ORIF (>3 weeks)
Iatrogenic
Tardy Ulnar nerve palsy: seen in valgus malunions