summary Extensor Tendon Injuries are traumatic injuries to the extensor tendons that can be caused by laceration, trauma, or overuse. Diagnosis is made clinically by physical examination and performing various provocative tests depending on the location of the injury. Treatment can be nonoperative or operative depending on the zone of injury. Epidemiology Anatomic location most commonly injured digit is the long finger zone VI is the most frequently injured zone Etiology Mechanism Zone I login to view 1 more bullet Zone II login to view 1 more bullet Zone V login to view 4 more bullets Classification Zones of Extensor Tendon Injuries Zone I Disruption of terminal extensor tendon distal to or at the DIP joint of the fingers and IP joint of the thumb (EPL) Mallet Finger Zone II Disruption of tendon over middle phalanx or proximal phalanx of thumb (EPL) Zone III Disruption over the PIP joint of digit (central slip) or MCP joint of thumb (EPL and EPB Boutonniere deformity Zone IV Disruption over the proximal phalanx of digit or metacarpal of thumb (EPL and EPB) Zone V Disruption over MCP joint of digit or CMC joint of thumb (EPL and EPB) "Fight bite" common Sagittal band rupture Zone VI Disruption over the metacarpal Nerve and vessel injury likely Zone VII Disruption at the wrist joint Must repair retinaculum to prevent bowstringing Tendon repair followed by immobilization with wrist in 40° extension and MCP joint in 20° flexion for 3-4 weeks Zone VIII Disruption at the distal forearm Extensor muscle belly Usually from penetrating trauma Often have associated neurologic injury Tendon repair followed by immobilization with elbow in flexion and wrist in extension Presentation Zone I Inability to extend at the DIP joint Zone III Elson test login to view 3 more bullets Zone V extensor lag and flexion loss common junctura tendinae may allow partial/temporary extension by connecting with intact adjacent extensor tendons sagittal band rupture login to view 2 more bullets Imaging Radiographs AP and lateral of digit to verify no bony avulsion (bony mallet) Treatment Nonoperative immobilization with early protected motion login to view 2 more bullets DIP extension splinting login to view 11 more bullets PIP extension splinting login to view 6 more bullets MCP extension splinting login to view 4 more bullets Operative immediate I&D login to view 5 more bullets tendon repair login to view 2 more bullets fixation of bony avulsion login to view 6 more bullets tendon reconstruction login to view 2 more bullets central slip reconstruction login to view 6 more bullets EIP to EPL tendon transfer login to view 2 more bullets Techniques Tendon Repair incision technique login to view 2 more bullets suture technique login to view 3 more bullets circumferential epitendinous suture login to view 1 more bullet repair failure login to view 2 more bullets Tendon Reconstruction usually done as two stage procedure login to view 2 more bullets available grafts include login to view 5 more bullets Tenolysis indications login to view 2 more bullets postoperative follow with extensive therapy Rehabilitation Early active short-arc motion (SAM) indications login to view 1 more bullet advantages over static immobilization login to view 4 more bullets Relative motion splint (yoke splint) positions the involved MCP joint in hyperextension relative to adjacent digits Indications login to view 1 more bullet advantages over static immobilization and dynamic splinting login to view 4 more bullets Complications Adhesion formation leads to loss of finger flexion common in zone IV and VII and older patients prevented with early protected ROM and dynamic splinting (zone IV) treatment login to view 2 more bullets Tendon rupture causes include poor suture material or surgical technique, aggressive therapy, and noncompliance incidence login to view 2 more bullets treatment login to view 2 more bullets Swan neck deformity caused by prolonged DIP flexion with dorsal subluxation of lateral bands and PIP joint hyperextension treatment login to view 2 more bullets Boutonniere deformity (DIP hyperextension) caused by central slip disruption and lateral band volar subluxation treatment login to view 2 more bullets