Essex-Lopresti Injuries: Biomechanics, Diagnosis, and Management

Anatomical & Biomechanical Foundation

• Forearm rotation is an evolutionary specialization unique to humans.
• Patients tolerate wrist fusion well. They do not tolerate loss of pronation and supination.
• Load distribution at the wrist is 80% through the radius and 20% through the ulna.
• Load shifts across the forearm. It reaches 40% radius and 60% ulna at the elbow level.
• The central band of the interosseous membrane (IOM) transfers this axial load.
• Central band fibers originate at the pronator teres insertion.
• Fibers run distally toward the ulna at an angle of 21 degrees.
• Simple radial head excision allows roughly 7 mm of proximal radial migration if the IOM is intact.
• Combined rupture of the IOM and Triangular Fibrocartilage Complex (TFCC) causes 15 mm of proximal migration.
• Complete migration leads to radiocapitellar impingement, ulnocarpal abutment, and severe wrist pain.

Historical Context & True Pathology

• Brockman (1931): First described distal radioulnar joint (DRUJ) subluxation after radial head excision.
• Peter Essex-Lopresti (1951): Reported two post-mortem cases of combined radial head fracture and DRUJ dislocation.
• Pathoanatomy involves a three-part longitudinal injury:
  • Radial head fracture (often comminuted).
  • Complete rupture of the forearm interosseous membrane (central band).
  • Disruption of the DRUJ with tearing of the TFCC.

Diagnostic Approach & Clinical Signs

• Mechanism: High-energy fall on an outstretched hand (FOOSH).
• Clinical Red Flag: Proximal elbow pain combined with forearm tenderness and wrist/DRUJ pain.
• Wrist pain may be absent initially. It manifests prominently if the radial head is mistakenly excised.
• Radiography: Always obtain wrist X-rays for any comminuted radial head fracture.
• Frequency: Michael Hausman (New York) noted that 60% of radial head fractures show IOM tears on MRI.
• Complete Essex-Lopresti dissociations occur in approximately 10% of cases.

Intraoperative Radial Pull Test

• Perform under fluoroscopy after preparing or removing the broken radial head.
• Apply longitudinal traction along the radius using a bone reduction clamp.
• Measure proximal translation relative to the distal ulna on wrist views.

Acute Management Algorithm

• Never excise the radial head: Complete excision leads to chronic proximal migration and joint collapse.
• Mason Type II: Stable internal screw fixation (tripod screw technique or low-profile plate).
• Comminuted (Mason Type III/IV): Replace with a metallic radial head arthroplasty as a rigid spacer.
• Fixation choices:
  • Smooth, loose-fitting stems (Graham King concept) function as rotating spacers.
  • Press-fit, porous-coated stems (Shawn O’Driscoll concept) achieve bony ingrowth.
  • Both approaches report successful outcomes; sizing head diameter and neck height correctly is critical.
• Stabilizing the DRUJ:
  • Transfix the radius and ulna using temporary K-wires in supination.
  • Perform an open or arthroscopic TFCC repair using suture anchors.
• Acute outcomes: Approximately 83% good-to-excellent results with early radial head replacement and DRUJ stabilization.

Chronic Essex-Lopresti Reconstruction

• Missed diagnosis occurs in roughly 50% of all cases.
• The Darrach Pitfall: Do not perform a simple Darrach distal ulna excision. The radius will continue migrating proximally, worsening forearm shortening.
• Failed Radial Head Excision: Insert a metallic radial head implant to restore length, combined with an open TFCC repair.
• Secondary Capitellar Arthrosis: If cartilage wear prevents placing a metallic head, excise the painful implant and perform formal IOM reconstruction.

IOM Reconstruction: Pronator Teres Transfer Technique

• Tendon Harvest: Elevate a longitudinal strip of the pronator teres tendon.
• Leave the distal tendon footprint attached to the radius.
• Orientation: Pass the tendon strip deep to the extensor tendons toward the ulna at a 21-degree angle.
• Measure the 21-degree angle intraoperatively using a sterile goniometer.
• Fixation: Pass the tendon through an ulnar drill hole and secure it under tension.
• Salvage Option: If multiple reconstructions fail, perform a one-bone forearm fusion in functional semi-pronation.