II. Definitions
- Monteggia Fracture
- Proximal Ulna Fracture AND Radial Head Dislocation
III. Mechanism
- Fall on Outstretched Hand WITH
- Extended elbow AND Hyperpronated Forearm
IV. Signs
- Decreased elbow range of motion
- Proximal third ulna tenderness, swelling, deformity suggesting Fracture of shaft (typically displaced)
- Proximal Radial Head Dislocation
- Perform a careful Hand Neurovascular Exam
- Risk of Radial Nerve injury (including posterior interosseous nerve which branches from Radial Nerve)
- Evaluate extension of thumb, wrist and MCP joint
V. Types: Bado Classification
- Type 1: Extension (60-70% of Fractures, esp. children)
- Radial head dislocates anteriorly
- Type 2: Flexion (15% of Fractures, esp. adults)
- Radial head dislocates posteriorly or posterior-laterally
- Type 3: Lateral (20% of Fractures)
- Radial head dislocates laterally or anterior-laterally
- Type 4: Combined (1% of Fractures)
- Radial head dislocates anteriorly AND
- Radial Fracture (in addition to the proximal Ulna Fracture)
VI. Differential Diagnosis
VII. Imaging: Forearm XRay
- Images
- Ulna Fracture may not be obvious (greenstick Fracture)
-
Radial Head Dislocation may be subtle and overlooked
- Draw a radiocapitellar line using lateral Elbow XRay (with elbow at 90 degrees)
- Radiocapitellar line drawn down the longitudinal midline of the radius should pass through the capitellum
- Xray joint above and below Forearm (standard protocol)
VIII. Management
- Acute Management
- Most adult cases will require operative management with ORIF
- Emergent orthopedic consult for displaced Monteggia Fracture Dislocations (unstable)
- Closed reduction AND Long Arm Splint immobilization for stable, non-displaced Fractures
- Reduce BOTH the Ulna Fracture and the Radial Head Dislocation
- Follow-up with orthopedic surgery
- Child: Closed reduction may suffice
- Adult: Open reduction and internal fixation (ORIF)
IX. Complications
- Missed Radial Head Dislocation
- Chronic unreducible dislocated radial head
- Results in Chronic Pain and limited Forearm supination and pronation
- Posterior interosseous nerve palsy
- Results from Radial Head Dislocation
- Results in loss of thumb extension and loss of metacarpophalangeal joint (MCP) extension
- Preserved wrist extension
X. References
- Beutel (2012) Orthopedics 35:138-44
- Delpont (2018) Orthop Traumatol Surg Res 104(1):S113-20
- Hartman, Morrissey and Kiel (2020) Crit Dec Emerg Med 34(1): 16-17
- Johnson and Silberman (2021) Monteggia Fractures, StatPearls, Treasure Island, FL