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Updated: May 24 2021

Isolated Ulnar Shaft Fracture

Images
https://upload.orthobullets.com/topic/422969/images/malunion_ulna..jpg
https://upload.orthobullets.com/topic/422969/images/ulnar_shaft_fracture..jpg
https://upload.orthobullets.com/topic/422969/images/orif_isolated_ulna..jpg
https://upload.orthobullets.com/topic/422969/images/masquelet_ulna..jpg
  • Summary
    • Isolated ulnar shaft fractures are rare fractures of the forearm caused by either direct blow to the forearm ("nightstick" fracture) or indirect trauma (fall).
    • Diagnosis can be made primarily by physical exam and plain radiographs.
    • Minimally displaced (< 50% displacement and < 10° of angulation) are often treated nonsurgically, while treatment has historically been surgical open reduction and internal fixation with compression plating for displaced fractures.
  • Epidemiology
    • Incidence
      • rare
        • < 1% of upper extremity fractures
    • Demographics
      • highest incidence in
        • men between age 10 and 20
        • women over age of 60
  • Etiology
    • Pathophysiology
      • mechanism of injury
        • direct trauma
          • direct blow to forearm ("nightstick" fracture)
        • indirect trauma
          • motor vehicle accidents
          • falls from height
            • axial load applied to the forearm through the hand
    • Associated conditions
      • elbow and DRUJ injuries
        • Monteggia fractures
        • Essex-Lopresti injuries
      • compartment syndrome
        • evaluate compartment pressures if concern for compartment syndrome
  • Anatomy
    • Osteology
      • axis of rotation of forearm runs through radial head (proximal) and ulna fovea (distal)
        • distal radius effectively rotates around the distal ulna in prono-supination
        • the ulna and radius form a functional unit; mal-angulation of ulna fractures can lead to limitation of forearm rotation
    • Ligaments
      • Interosseous membrane (IOM)
        • occupies the space between the radius and ulna
          • permits rotation of the radius around the ulna
        • comprised of 5 ligaments
          • central band is key portion of IOM to be reconstructed
          • accessory band
          • distal oblique bundle
          • proximal oblique cord
          • dorsal oblique accessory cord
  • Classification
    • Descriptive
      • closed versus open
      • location
      • comminuted, segmental, multi-fragmented
      • displacement
      • angulation
      • rotational alignment
    • OTA Classification
      • OTA classification
      • Type A
      • Simple fracture
      • Spiral (A1)
      • Oblique (A2)
      • Transverse (A3)
      • Type B
      • Wedge fracture
      • Intact (B2)
      • Fragmentary (B3)
      • Type C
      • Multifragmentary fracture
      • Intact segmental (C2)
      • Fragmentary (C3)
  • Presentation
    • Symptoms
      • pain and swelling
      • loss of forearm and hand function
    • Physical exam
      • inspection
        • gross deformity
        • open injuries
        • check for tense forearm compartments
      • neurovascular exam
        • assess radial and ulnar pulses
        • document median, radial, and ulnar nerve function
      • provocative tests
        • pain with passive stretch of fingers
          • alert to impending or present compartment syndrome
  • Imaging
    • Radiographs
      • recommended views
        • AP and lateral views of the forearm
      • additional views
        • oblique forearm views for further fracture definition
        • ipsilateral AP and lateral of the wrist and elbow
          • to evaluate for associated fractures or dislocation
          • radial head must be aligned with the capitulum on all views
  • Treatment
    • Nonoperative
      • cast or brace immobilization, soft compression dressing
        • indications
          • isolated nondisplaced or distal 2/3 ulna shaft fx (nightstick fx) with
            • < 50% displacement and
            • < 10° of angulation
        • modality
          • bracing
            • functional fracture brace
          • casting
            • Muenster cast with good interosseous mold
          • soft compression dressings
            • allowing immediate mobilization
        • outcomes
          • union rates > 92% if above criteria met
          • similar union and functional outcomes with casting and bracing/soft compression dressings
    • Operative
      • external fixation
        • indications
          • severe soft tissue injury (Gustilo IIIB)
      • ORIF
        • indications
          • displaced distal 2/3 isolated ulna fractures
          • proximal 1/3 isolated ulna fractures
          • Gustilo I, II, and IIIa open fractures may be treated with primary ORIF
        • outcomes
          • goal is for cortical opposition, compression, and restoration of forearm anatomy
      • ORIF with bone grafting
        • indications
          • open fractures with significant bone loss (bone grafting often performed in a delayed fashion)
        • outcomes
          • use of autograft is critical to achieve fracture union
        • technique
          • cancellous autograft
            • indications
              • ulnar fractures with significant bone loss
          • vascularized fibula grafts
            • indications
              • can be used for large defects and have a lower rate of infection
          • Masquelet technique
            • indications
              • utilized in cases of non-union or open fractures with significant bone loss
      • IM nailing
        • indications
          • poor soft-tissue integrity 
        • outcomes
          • recent studies have shown similar union rates compared to ORIF for isolated ulnar shaft fractures
  • Techniques
    • Cast or brace immobilization, soft compression dressing
      • technique
        • cast/brace may extend just above elbow to control forearm rotation, however, randomized studies have shown no difference in outcomes between above elbow and below elbow immobilization
          • monitor very closely (~1 week) for displacement
          • should be worn for at least 6 weeks
          • Some authors have advocated for immediate mobilization as tolerated
    • External fixation
      • technique
        • 2nd and 3rd metacarpal shaft can both be utilized for distal pin placement
        • pin diameter should not exceed 4 mm
    • ORIF
      • approach
        • subcutaneous approach to ulna shaft
      • technique
        • 3.5 mm DCP plate (AO technique) is standard
          • 4.5 plates no longer used due to increased rate of re-fracture following removal
        • compression mode preferred when the fracture allows to achieve anatomic primary bony healing
          • to minimize strain, six cortices proximal and distal to fracture should be engaged
        • locked plates are increasingly indicated over conventional plates in osteoporotic bone
        • bridge plating may be used in extensively comminuted fractures
        • interfragmentary lag screws (2.0 or 2.7 screws) if necessary
        • open fractures
          • irrigation and debridement should be performed to remove any contaminated tissue or bony fragments without soft tissue attachments
      • postoperative care
        • early ROM unless there is an injury to proximal or distal joint
        • should be managed with a period of non-weight bearing due to risk of secondary displacement of the fracture
          • generally 6 weeks
    • ORIF with bone grafting
      • technique
        • bone graft options
          • cancellous autograft
            • iliac crest, proxmial tibia, reamer-irrigator-aspirator (RIA)
          • vascularized fibula grafts
          • Masquelet technique ("induced-membrane" technique) can also be utilized in cases of non-union or open fractures with significant bone loss
            • 2 stage technique
              • 1st stage: I&D, cement spacer and temporizing fixation
              • 2nd stage: placement of bone graft into "induced membrane" and definitive fixation
                • Studies show optimal time frame for bone grafting to be 4-6 weeks after placement of cement spacer
    • IM nailing
      • approach
        • inserted through the posterior olecranon
      • technique
        • may use a small incision at fracture site to facilitate passing of nail
  • Complications
    • Infection
      • incidence
        • 3% incidence with ORIF
      • risk factors
        • open fractures
    • Compartment syndrome
      • incidence
        • up to 15% depending on mechanism and fracture characteristics
      • risk factors
        • high energy crush injury
        • open fractures
        • low velocity GSWs
        • vascular injuries
        • coagulopathies (DIC)
    • Nonunion
      • incidence
        • < 5% after compression plating
        • up to 12% in extensively comminuted fractures treated with bridge plating
      • risk factors
        • extensive comminution
        • poorly applied plate fixation
      • treatment
        • atrophic nonunions can be treated with 3.5 mm plates and autogenous cancellous bone grafting
        • Infection and atrophic nonunions can also be treated with the Masquelet technique
        • Hypertrophic nonunions treated with debridement and compression plating
    • Malunion
      • risk factors
        • direct correlation between restoration of radial bow and functional outcome
    • Neurovascular injury
      • risk factors
        • PIN injury with Monteggia fxs
        • Type III open fxs
      • treatment
        • observe for three months to see if nerve function returns
          • explore if no return of function after 3 months
    • Refracture
      • incidence
        • up to 10% with early hardware removal
      • risk factors
        • removing plate too early
          • plates should not be removed < 1 year from implantation
        • large plates (4.5 mm)
        • comminuted fractures
        • persistent radiographic lucency
      • treatment
        • wear functional forearm brace for 6 weeks and protect activity for 3 months after plate removal
  • Prognosis
    • For minimally displaced and angulated fractures (< 50% displacement and < 10° of angulation), nonoperative management has equivalent clinical outcomes to surgical treatment.
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