Pediatric Lateral Condyle Humerus Fracture : Review

A) Epidemiology:

1. 2nd commonest fracture around elbow after supracondylar fracture
2. Commonest age of occurrence: 5-10 years
3. Lateral condylar fracture is common than medial condylar fracture due to 2 reasons:
   • Radius articulates with the lateral part of the condyle and therefore the force from sudden impacts is primarily directed laterally.
   • Lateral epicondylar ridge is smaller and weaker than its medial counterpart.
4. It is the fracture of necessity i.e. needs ORIF
5. Most fractures are Type IV Salter Harris fractures

B) Mechanism of Injury:

• Pull-off theory (Jakob): Avulsion of lateral condyle by ECRL and brachioradialis during adduction of supinated forearm
• Push-off theory (Milch): Fall on outstretched hand causes impaction of radial head into the lateral condyle causing fracture

C) Classifications:

a. Milch: Fracture line based –

1. Milch Type I: Fracture line lateral to trochelar groove (Salter harris type IV; stable)
2. Milch Type II: Fracture line into trochlear groove (Salter harris type II; unstable; more common)

b. Jakob and Weiss: Displacement and articular congruency based –

1. Type I: <2mm displacement
2. Type II: ≥2mm displacement but intact articular cartilage
3. Type III: ≥2mm displacement but associated disruption of the articular surface

Modified Weiss classification: No need for arthrogram
1. Type I: <2 mm displacement
2. Type II: 2-4 mm displacement
3. Type III: >4 mm displacement (displacement of >4 mm correlated with disruption of cartilaginous hinge, shown by arthrogram)

c. Song: Stage of fracture progression based –

D) History and Examination:

1. Swelling and tenderness over lateral aspect of elbow
2. Reluctance to use the arm and resistance to passive motion
3. Can lead to minimal swelling and deformity, leading to delayed presentation
4. Increased pain with resisted wrist extension/flexion

E) X-ray examination:

1. AP and lateral views
2. Internal oblique view: detects minimally displaced fracture as the fractured fragment frequently lies posterolaterally

Lateral humeral condyle fracture plane is at a mean of 21+/-2 degrees to the anatomical axis on a lateral radiograph. Therefore, an AP radiograph of the humerus taken at 20 degrees elevation results in a view along the fracture plane and offers a view of maximal displacement of the fracture.

F) Treatment:

1. Weiss type 1, Song 1: Can be managed with long arm cast with forearm in supination and wrist in extension (to relax deforming muscles i.e. extensor-supinator complex)

• Duration: 4-6 weeks
• Follow up: Weekly out of cast X-rays (Internal oblique, AP, lateral and 20 degree AP)

2. Weiss type 2, Song 2-4: Closed reduction and percutaneous fixation can be performed if satisfactory reduction achieved (fracture gap <1-2 mm)

• Surgical Technique for Closed Reduction and Percutaneous Pin… : Techniques in Orthopaedics (lww.com)
• Can use K-wires or Cannulated screws
• Using 2 instead of 3 K-wires when stability is adequately achieved improves range of motion and reduces bone spur formation

3. Weiss type 3, Song 5, failed closed reduction: Open reduction and Internal fixation

• Lateral approach to the pediatric distal humerus (aofoundation.org)
• K-wires, Metaphyseal screw fixation or Transcapitellar screw fixation
• Surgical tips:
  • Slight anterior incision to reduce stretch of scar
  • Use of a dental mirror to see across the joint surface and confirm reduction.
  • Hockey stick arthrotomy in line with the fibres of the lateral radial collateral and annular ligament.
  • 20 degrees elevated distal humeral views to confirm reduction of the fracture intraoperatively.
  • Avoid dissection of the posterior aspect of the lateral condyle as this will result in damage to the only blood supply to the capitellum.
    • Lateral epicondylar artery (from radial collateral artery) and branch from medial collateral artery both enter posteriorly and anastomose.

K-wire configuration: 1.6 or 2 mm K-wires
1st K-wire: From center of capitellum, parallel to the joint line and advance to medial part of trochlea (to hold the joint surface aligned)
2nd K-wire: Inserted behind the first K-wire and advanced proximally along the lateral column of the humerus as far as the anterior cortex.

There should be atleast 60 degrees divergence between K-wires.
K-wires should have posterior to anterior angle on lateral view.

G) Complications:

1. Reduced range of motion
2. Avascular necrosis (AVN)/fish tail deformity: as a result of posterior dissection
3. Non-union/Malunion: due to wide fracture displacement due to constant extensor pull
   • May lead to cubitus valgus deformity (due to undergrowth of lateral condyle) and tardy ulnar nerve palsy
   • Cubitus valgus deformity is treated with wedge osteotomy if the angle is more than 20 degrees
4. Tardy ulnar nerve palsy: Ulnar nerve palsy seen after several years resulting from friction neuritis (after stretching) due to valgus deformity. It is treated with anterior interposition of the ulnar nerve.
5. Lateral overgrowth/prominence: sometimes, overgrowth of lateral condyle may occur due to overstimulation of lateral growth plate and parents should be counselled about this in advance; this may lead to cubitus varus (gunstock deformity)
6. Pin tract infections

References:

1. Stevenson, R. A., & Perry, D. C. (2018). Paediatric lateral condyle fractures of the distal humerus. Orthopaedics and Trauma. doi:10.1016/j.mporth.2018.07.013
2. Martins T, Marappa-Ganeshan R. Pediatric Lateral Humeral Condyle Fractures. [Updated 2022 Dec 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK560664/