Paediatric Monteggia Fractures

• Monteggia fracture first described by Giovanni Monteggia in 1814.
• 16-50% of paediatric Monteggia fractures are missed initially at presentation.

Anatomy

• Annular ligament and quadrate ligament are primary static stabilizers of proximal radioulnar joint.
• Weitbrecht ligament or oblique cord which extend from just distal to radial notch on the ulna to the bicipital tuberosity and the interosseous ligament are the other stabilizers.
• These ligaments are most taut in supination because of radial bow and elliptical shape of radial head, and the longer axis of the elliptical radial head is perpendicular to radial notch of ulna in supination.
• 80% of load from carpus is carried by radius.
• 33% of valgus stability of elbow provided by radial head.

Classification

Letts Classification

1. Anterior dislocation with apex anterior plastic bowing of ulna
2. Anterior dislocation with apex anterior green stick fracture of ulna.
3. Anterior dislocation with apex anterior complete fracture
4. Posterior dislocation with apex-posterior fracture of ulna
5. Lateral dislocation with apex-lateral fracture of ulna

75% of acute paeditric Monteggia injuries and 85% of missed paediatric Monteggia fractures are anterior dislocation types.

Bado classification

1. Anterior dislocation with apex-anterior fracture of ulna. Due to hyperextension (hyperextension theory of Tompkins)
2. Posterior dislocation with apex-posterior fracture of ulna. Due to fall with elbow flexed to 60 degrees.
3. Lateral dislocation with apex-lateral fracture of ulna. Due to varus stress.
4. Radial head dislocation with fracture of radius and ulna. Due to hyper-pronation.

Natural history

• Ulnar fracture unites.
• The annular ligament and anterior capsular structures fall into radiocapitellar joint producing block to reduction.
• Dysplastic changes develop in the radial head, capitellum and the radial notch of ulna.
• Valgus instability of elbow develops.
• Cubitus valgus develops.
• Secondary osteoarthritis of elbow develops.
• Late paralysis of ulnar nerve can develop due to cubitus valgus.
• Late median nerve and posterior interosseous nerve palsy can develop due to tenting by the anteriorly dislocated radial head.

Diagnosis

• Storen line – The axis of radius passes through the centre of the capitellum.
• Head neck ratio- Ratio between widest part of head and narrowest part of neck. Normal is less than 1.5.
• Lincoln and Mubarak method- The line drawn along the subcutaneous border of ulna is within <2-3mm of the ulnar shaft. if more, the ulna is deformed.

Treatment

• In acute setting, treatment is by closed reduction and long arm casting in supination.
• Closed reduction can be attempted up to 4 weeks.
• Contraindications for surgery are duration more than 3 years and age > 12 years.
• Generally reduction is successful if done within one year of injury irrespective of age.
• Depending on the chronicity and the severity of changes, adjunct procedures are required to maintain the reduction.
• Treatment needs 3 strategies
  • Reduction of radial head
  • Reconstruction of ligamentous stabilizers
  • Correction of ulnar deformity
• Bell Tawse procedure
  • Described in 1968.
  • Posterolateral approach
  • Excision of interposed tissue
  • Reduction of radial head
  • Reconstruction of annular ligament by passing the central slip of triceps circumferentially around the neck of radius.
  • According to Seel and Peterson, the reconstructed ligament produces a posterolateral pull and hence is useful for anteromedial dislocations, but not for other types of dislocations.
• Seel and Peterson developed a 2-drill hole technique that produces a centrally directed force.
• Lloyd Roberts and Bucknill added radio-capitellar pinning to Bell Tawse procedure to protect the reconstructed ligament for 6 weeks.
• To avoid intra-articular pin breakage, Letts described radioulnar pinning instead of radio-capitellar pinning.
• Kalamchi procedure
  • Osteotomy of ulna using multiple passes of K wire and open reduction of radial head.
• Ladermann procedure
  • Closed reduction of radial head after ulnar osteotomy and lengthening of ulna.
• Bor technique
  • Using Ilizarov technique to lengthen the ulna, angulate the ulna and reduce the radial head.
• According to Delpont (2014) annular ligament reconstruction is not beneficial in conjunction with ulnar osteotomy.  (Delpont M, Jouve JL, Sales de Gauzy J, Louahem D, Vialle R, Bollini G, Accadbled F, Cottalorda J. Proximal ulnar osteotomy in the treatment of neglected childhood Monteggia lesion. Orthop Traumatol Surg Res. 2014 Nov; 100(7):803-7. Epub 2014 Oct 7.)
• Osteotomy is useful in Bado 1 lesions but less effective in Bado 3 lesions.
• Ulnar osteotomy can be corrective (Straightens the posterior cortical line), over-corrective (reverses original deformity) or stabilizing (reduces the radial head).
• Overcorrection has been shown to produce significantly better outcomes. (Inoue G, Shionoya K. Corrective ulnar osteotomy for malunited anterior Monteggia lesions in children. 12 patients followed for 1-12 years. Acta Orthop Scand. 1998 Feb;69(1):73-6.)
• Osteotomy can be at the CORA or at the proximal metaphyseal area. Osteotomy at the proximal metaphyseal area have better healing and can be performed through the same incision.