Monteggia Fractures - Trauma

Summary
- A Monteggia fracture is defined as a proximal 1/3 ulna fracture with an associated radial head dislocation.
- Diagnosis is made with forearm and elbow radiographs to check for congruency of the radiocapitellar joint in the setting of an ulna fracture.
- Treatment can be isolated closed reduction in the pediatric population (if radiocapitellar joint remains stable). Adults and unstable injuries generally require ORIF of the ulna.

Epidemiology
- Incidence
  - rare in adults
  - more common in children with peak incidence between 4 and 10 years of age
    
    different treatment protocol for children

Etiology
- Associated injuries
  - may be part of complex injury pattern including
    
    olecranon fracture-dislocation
    
    radial head fx
    
    coronoid fx
    
    LCL injury
    
    terrible triad of elbow

Anatomy
- Ligament
  - annular ligament

                        Classification
                    
                        Bado Classification
                    
                        Type I
                    
                        60%
                    
                        Fracture of the proximal or middle third of the ulna with anterior dislocation of the radial head (most common in children and young adults)
                    
                        Type II
                    
                        15%
                    
                        Fracture of the proximal or middle third of the ulna with posterior dislocation of the radial head (70 to 80% of adult Monteggia fractures)
                    
                        Type III
                    
                        20%
                    
                        Fracture of the ulnar metaphysis (distal to coronoid process) with lateral dislocation of the radial head
                    
                        Type IV
                    
                        5%
                    
                        Fracture of the proximal or middle third of the ulna and radius with dislocation of the radial head in any direction
                    
                        Jupiter Classification of Type II Monteggia Fracture-Dislocations
                    
                        Type IIA
                    
                        Coronoid level
                    
                        Type IIB
                    
                        Metaphyseal-diaphyseal junction
                    
                        Type IIC
                    
                        Distal to coronoid
                    
                        Type IID
                    
                        Fracture extending to distal half of ulna

Presentation
- Symptoms
  - pain and swelling at elbow joint
- Physical exam
  - inspection
    
    may or may not be obvious dislocation at radiocapitellar joint
    
    should evaluate skin integrity
  - ROM & instability
    
    may be loss of ROM at elbow due to dislocation
  - neurovascular exam
    
    PIN neuropathy
    
    radial deviation of hand with wrist extension
    
    weakness of thumb extension
    
    weakness of MCP extension
    
    most likely nerve injury

Imaging
- Radiographs
  - recommended view
    
    AP and Lateral of elbow, wrist, and forearm
- CT scan
  - helpful in fractures involving coronoid, olecranon, and radial head

Treatment
- Nonoperative
  - closed reduction
    
    indications
    
    more common and successful in children
    
    must ensure stabilty and anatomic alignment of ulna fracture
    
    technique
    
    cast in supination for Bado I and III
- Operative
  - ORIF of ulna shaft fracture
    
    indications
    
    acute fractures which are open or unstable (long oblique)
    
    comminuted fractures
    
    most Monteggia fractures in adults are treated surgically
  - ORIF of ulna shaft fracture, open reduction of radial head
    
    indications
    
    failure to reduce radial head with ORIF of ulnar shaft only
    
    ensure ulnar reduction is correct
    
    complex injury pattern
    
    Monteggia "variants" with associated radial head fracture
  - IM Nailing of ulna
    
    indications
    
    transverse or short oblique fracture

Techniques
- ORIF of ulnar shaft fracture
  - approach
    
    lateral decubitus position with arm over padded support
    
    midline posterior incision placed lateral to tip of olecranon
    
    develop interval between flexor carpi ulnaris and anconeus along ulnar border proximally, and interval between FCU and ECU distally
  - techniques
    
    with proper alignment of ulna radial head usually reduces and open reduction of radial head is rarely needed
    
    failure to align ulna will lead to chronic dislocation of radial head
- ORIF of radial head
  - approach
    
    posterolateral (Kocher) approach
  - technique
    
    annular ligament often found interposed in radiocapitellar joint preventing anatomic reduction after ulnar ORIF
    
    treatment based on involved components (radial head, coronoid, LCL)

Complications
- PIN neuropathy
  - up to 10% in acute injuries
  - treatment
    
    observation for 2-3 months
    
    spontaneously resolves in most cases
    
    if no improvement obtain nerve conduction studies
- Malunion with radial head dislocation
  - usually caused by failure to obtain anatomic alignment of ulna
  - treatment
    
    ulnar osteotomy and open reduction of the radial head

Prognosis
- If diagnosis is delayed greater than 2-3 weeks complication rates increase significantly

Action	Numeric Key	Letter Key	Function Key
Show Bullets		S	Enter (frontside only)
20%	1	N
40%	2	H
60%	3	F	Enter (backside only)
80%	4	E
100%	5	M
Toss	0	T

Bado Classification
Type I	60%	Fracture of the proximal or middle third of the ulna with anterior dislocation of the radial head (most common in children and young adults)
Type II	15%	Fracture of the proximal or middle third of the ulna with posterior dislocation of the radial head (70 to 80% of adult Monteggia fractures)
Type III	20%	Fracture of the ulnar metaphysis (distal to coronoid process) with lateral dislocation of the radial head
Type IV	5%	Fracture of the proximal or middle third of the ulna and radius with dislocation of the radial head in any direction

Jupiter Classification of Type II Monteggia Fracture-Dislocations
Type IIA	Coronoid level
Type IIB	Metaphyseal-diaphyseal junction
Type IIC	Distal to coronoid
Type IID	Fracture extending to distal half of ulna