Emergent Care / Stabilization:

• Reduction
• Immobilization

Causes / typical injury mechanism: Ulnar shaft fractures typically result from direct trauma to the medial forearm, such as with blocking a blow from a bat or a nightstick. These are commonly called "nightstick fractures." This fracture can also be seen after a fall.

Classic history and presentation: Patients present with localized tenderness and swelling of the forearm following a blow to the medial forearm or a fall.

Prevalence: Bimodal distribution.

• Younger, active men
• Older women

Risk factors:

• Athletic participation or an active lifestyle
• Increased age in women, due to osteopenia / osteoporosis
• Living in an area with a higher prevalence of violence

Pathophysiology: A direct blow to the ulna or axial load across the ulna leads to this type of fracture.

Grade / classification system: 
Stability

• Stable –
• Displacement of less than 50%
• Angulation of less than 15 degrees
• Location in middle and distal third of ulna

• Unstable –
• Displacement of more than 50%
• Angulation of more than 15 degrees
• Ipsilateral instability of distal radial ulnar joint or proximal radial ulnar joint

AO / Orthopaedic Trauma Association (OTA) Classification
Ulna fractures are classified as 2U fractures, and then further classified as:

• 2U2: Diaphyseal segment of ulna fracture

Ulna fractures are further classified by type:

• Type A: Simple fractures
  • A1: Spiral
  • A2: Oblique (greater than or equal to 30 degrees)
  • A3: Transverse (less than 30 degrees)
• Type B: Wedge fracture
  • B2: Intact wedge
  • B3: Fragmentary wedge
• Type C: Multifragmentary
  • C2: Intact segmental
  • C3: Fragmentary segmental

Ulnar shaft fractures should also be classified as open or closed.