Forearm Fractures, Study notes of Anatomy

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Forearm Fractures

Sean T. Campbell, MD

Assistant Attending

Orthopedic Trauma Service

Hospital for Special Surgery, New York, NY

Objectives

• Understand rationale for surgery for forearm fractures
• Understand which segment is unstable based on injury pattern
• Identify goals of surgery based on injury pattern
• Review surgical techniques

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Anatomy

• Two bones that function as a forearm joint to allow rotation
  • Radius
    • Radial bow in coronal plane
  • Ulna
    • Proximal dorsal angulation in sagittal plane
    • Not a straight bone
    • Distinct bow in coronal plane (see next slides)
  • Proximal radioulnar joint (PRUJ)
    • Articulation of radial head with proximal ulna
  • Distal radioulnar joint
    • Articulation of ulnar head with distal radius
  • Interosseous membrane Hreha J+, Snow B+ Image from: Jarvie, Geoff C. MD, MHSc, FRCSC; Kilb, Brett MD, MSc, BS,†; Willing, Ryan PhD, BEng‡; King, Graham J. MD, MSc, FRCSC‡; Daneshvar, Parham MD, BS* Apparent Proximal Ulna Dorsal Angulation Variation Due to Ulnar Rotation, Journal of Orthopaedic Trauma: April 2019 - Volume 33 - Issue 4 - p e120-e123 doi: 10.1097/BOT.

Anatomy

• Radial bow allows for pronosupination
  • Must be restored surgically when compromised
  • Multiple methods for assessment of radial bow
    • Comparison to contralateral images
    • Direct anatomic reduction of simple fractures
    • Biceps tuberosity 180 degrees of radial styloid
• Note opposite apex medial bow of ulna
  • Not a straight bone

Image from: Rockwood and Green, 9e, fig 41-

Initial Presentation

• Antibiotics for open fractures
• Careful attention to neurovascular status
• Physical and radiographic exam of wrist and elbow joints
• Temporizing splint immobilization above the elbow
• High risk for compartment syndrome - Especially high energy mechanisms - Be familiar with technique for forearm compartment release: OTA video library

Surgical Indications

• Most fractures are operative in adults
  • Both bone fractures- inherently unstable
  • Loss of radial bow interferes with pronosupination
  • Single bone diaphyseal injuries
    • Often result in
      • PRUJ instability (Monteggia)
      • DRUJ instability (Galeazzi)
• Exceptions
  • Some nondisplaced single bone injuries (i.e. nightstick fracture of ulna)
    • With intact PRUJ/DRUJ
• Outcomes
  • In general good
  • Moderate decrease in perceived strength*

• Droll+

Surgical Goals for All Forearm Fractures

• Restoration of forearm anatomy
  • Length/alignment/rotation (L/A/R) + correct bow
• Stable and congruent elbow and wrist joints
  • Address fracture of sigmoid notch or radial head
• Robust fixation to allow early motion
  • Avoid thin/tubular plates
• Intelligent fixation based on fracture pattern
  • Simple patterns- anatomic reduction and compression
  • Comminuted patterns- restoration of L/A/R/bow with bridge

plating

Surgical Toolbox: Diaphyseal Both Bone

Positioning

• Supine, radiolucent hand table
  • Preferred: Most diaphyseal and distal fractures
  • Disadvantage: must flex (and hold flexed) elbow to approach ulna
  • Addressing radius first typically easier in this position
    • Gives stability to forearm for treatment of ulna in the elbow-flexed position
• Lateral with elbow flexed 90 degrees
  • Advantage: Complex proximal ulna fracture; transolecranon fracture-dislocation
  • Disadvantage: unfamiliar positioning for radius- may require repositioning
  • Indications:
    • Difficult/segmental proximal ulna fracture
    • Ipsilateral humerus fracture to be addressed with same anesthetic

Surgical Toolbox: Diaphyseal Both Bone

Clinical photos demonstrating the volar approach to the radius.

Middle: Elevator is pointing at the superficial branch of the radial nerve.

Right: The fracture has been exposed (elevator at fracture line). The white structure just ulnar to the elevator is the pronator teres tendon. White arrow points to radial artery.

Surgical Toolbox: Diaphyseal Both Bone

Ulnar Exposure

• ECU/FCU split
  • Be aware of ulnar bow
  • Ulna is not truly “subcutaneous” throughout full length
    • ECU/FCU interval may “cross” over border of the bone
    • Utilize correct interval to preserve muscle as possible
  • Extensile proximally into posterior approach to humerus
  • OTA video library example

Surgical toolbox: Fixation of Diaphyseal BBFF

• Simple fractures
  • Lag screw/neutralization plating for obliquity fracture
    • Countersink volar 2.4mm lag screws if under plate
  • Dynamic compression plating for transverse fracture
    • Mini-fragment plate can be used for provisional reduction
  • Plate selection
    • 3.5mm LCDCP or similar on radius and ulna
      • 2.7 DCP in smaller patients on ulna
      • Avoid tubular or flexible plates
    • Slight prebend needed if compression plating
  • Comminuted/Segmental bone loss fractures
    • Long contoured plates with well balanced screw spread preferred
  • Full length films (flat plates) can be useful for assessing radial bow - Consider comparison views of contralateral side

Case Example: Both Bone Forearm Fracture

• Bridge plating due to comminution
• Eccentric straight plate highlights restored radial bow

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Surgical Toolbox: Galeazzi

• Preoperative examination of contralateral DRUJ
• Clinical exam after radius fixation to determine next

steps

• Restoration of radius length and bow often

restores DRUJ stability

• if unstable: TFCC repair, splinting in position of

reduction/stability, pinning in position of

reduction/stability (usually supination)

• Typically dorsal instability, but volar instability

possible

• Author’s protocol for DRUJ
  • If lax compared to contralateral, splint in

stable position x2 weeks

• If dislocating with pronosupination, pin in

reduced position x4 weeks

• In general, good outcomes if anatomy restored* *Giannoulis+

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Monteggia Fracture

• Ulna shaft fracture with radial head dislocation (PRUJ

instability)

• Classification system based on direction of

dislocation (next slide - diagram of classification)

• Associated injuries:
  • LUCL injury, radial head fracture, coronoid

fracture

• Outcomes
  • In general, good
  • Poorer with Bado type II fractures (see next

slide), associated radial head and coronoid

fractures*

*Sreekumar+