I.     Relationship of radius and ulna important for pronation/supination of forearm and extremity function
II.    Often high-energy trauma; frequently open fractures or large soft tissue zone of injury
III.   Anatomic Principles
        a.  Ulna is subcutaneous at posterior apex, with slight apex posterior bow
        b.  Radius rotates about stationary ulna (axial rotation proximally, axial rotation/translation distally)
        c.  Interosseous membrane/ligament (IOL) extends from radius proximally to ulna distally; transfers forces between
bones of forearm. Radius bears 80% of compressive load at DRUJ, 60% at PRUJ
       d.  PRUJ stabilized by annular and quadrate ligaments
and interosseous membrane
       e.  DRUJ stabilized by TFCC: including articular disc, dorsal and volar radioulnar ligaments (deep ligamentum ubcruentum, prevents rotation), ulnar carpal ligaments, and ECU sheath
IV.   Operative Exposures
       a.  Ulna is subcutaneous at posterior apex–elevate muscle
extraperiosteally in one plane
       b.  Dorsal approach to radius (Thompson)–skin incision in line with Lister’s and lateral epicondyle; internervous plane between EDC (PIN) and ECRB (radial n.); dissect from distal to proximal starting at 1st extensor compartment.
                 i.  Proximally - protect PIN between heads of supinator, expose radius in maximal supination
                ii.  Mid-radius - mobilize and retract APL and EPB
               iii.  Distally - interval between EPL and ECRL/ECRB
       c.  Volar approach to radius (Henry)–skin incision in line with lateral margin of biceps at elbow and radial styloid; internervous plane between brachioradialis (radial n.) and flexor carpi radialis and pronator teres (median n.); dissect from distal to proximal, ligating perforators and mobilizing the radial artery medially with FCR and the superficial radial nerve (undersurface of BR) laterally
                 i.  Deep dissection begins proximally, with forearm in maximal supination to protect PIN. Follow lateral edge of biceps tendon to insertion of supinator and elevate supinator from radius. Pronator teres can be detached or plate can be placed over insertion
                ii.  Mid-radius, must elevate body of FDS to expose bone
               iii.  Distally, elevate pronator quadratus and FPL extraperiosteally
       d.  Forearm compartment release - three compartments (volar, dorsal, and mobile wad) usually all decompressed with volar. Should do concurrent release of lacertus fibrosis and carpal tunnel.
V.     Fracture Treatment
       a.  Goal is to achieve anatomic reduction and stable fixation to permit early forearm mobilization.
       b.  Treatment of choice is a 3.5-mm LCDC plate with three bicortical screws proximally and distally to fracture. Intramedullary implants cannot control rotation and may not restore radial bow.
       c.  Isolated ulnar (“nightstick”) fractures non-operatively if <50% translation and <10° angulation
       d.  Immediate ORIF of forearm fractures is acceptable in open fractures unless grossly contaminated
       e.  Removal of plates associated with risk of refracture
(especially if less than 1 year post-op) due to stress-shielding and disruption of vascular supply. Indicated if plate is definite
source of discomfort
VI.   Fracture-Dislocations
       a.  Galeazzi–radial diaphyseal fracture and DRUJ dislocation. Check radiographs for ulnar styloid fracture, DRUJ widening, dislocation of radius on true lateral, or >5 mm shortening of radius with loading. Consider temporary DRUJ pinning if unstable. Repair ulnar styloid if fractured at base.
       b.  Monteggia–proximal ulna fracture with dislocation radial head. Radial shaft bisects capitellum in all radiographics. Bado classification describes direction of displacement (I: Anterior, II: Posterior, III: Lateral, IV: with radial head fx). Instability after reduction associated with ulnar malreduction.
       c.  Essex-Lopresti–radial head fracture with disruption of IOL and DRUJ. If missed, radius can migrate proximally, causing motion limitations, weakness, and pain.
       d.  Bipolar forearm fracture-dislocation / radioulnar dissociation–fractures with disruption of IOL.