Hand and finger tendon injuries

Background

Tendons of the upper extremity anatomy

• Fingers
  • FDP (DIP flexion)
  • FDS (PIP flexion)
  • Extensor dig communis (extension)
    • Mallet = DIP
    • Boutonniere = PIP
• Thumb
  • Flx pollicis longus (flexion)
  • Ex poll longus (DIP ext)
  • Ex poll brevis (MCP ext)
  • Abductor poll longus (abduction)
• Wrist
  • Flexor carpi ulnaris (flx + ulnar deviation)
  • Flexor carpi radialis (flx + radial dev)
  • Extensor carpi ulnaris (ext + ulnar dev)
  • Extensor carpi radialis (ext + radial dev)

Flexor

Flexor zones

Management

• Primary repair should occur within 12hr; secondary repair can occur up to 4wk after injury
• Hand surgeon should repair all flexor tendon lacerations
• If hand surgeon is not immediately available:
  • Irrigate open wounds and close with 5-0 nylon
  • Most advocate antibiotics
  • Splint hand with:
    • Wrist in 30 deg of flexion
    • MCP joints in 70 deg of flexion
    • IP joint flexed 10-15 deg of flexion

Extensor

Background

• Most common site of tendon injuries b/c of superfical location on dorsum of hand
• If tendon lac suspected but unable to be located it is ok to refer to specialist within 3d
  • Delayed repair up to 7-10d usually has equal outcome to immediate repair
• Zones V-VII Splinting (after repair)
  • Requires splinting with:
    • Wrist in 15 deg extension
    • MCP joint in 15 deg flexion
    • IP join in 15 deg flexion in involved and adjacent digit

Zones

Extensor zones

• Zone I
  • Area over distal phalanx and DIP joint
  • Complete laceration at this level will result in DIP joint flexed 40 degrees
  • "Mallet finger" refers to closed disruption of distal extensor apparatus
    • Occurs due to sudden forceful flexion of extended finger (finger gets "jammed")
    • May occur due to tear of tendon itself or avultion fracture of dorsal base of phalanx
    • Most common tendon injury in athletes
  • Immobilize DIP joint only in continuous slight hyperextension for 6-8wks
• Zone II
  • Area over middle phalanx
  • Treatment is similar to zone I injuries
• Zone III
  • Area over the PIP joint
  • Central tendon is most commonly injured structure
  • Controversial whether conservative or operative management is best
    • Closed injuries are initially treated with PIP joint immobilized in extension for 5-6wks
    • Must be followed closely by hand specialist
• Zone IV
  • Involves area over proximal phalanx
  • Clinical findings are similar to zone III injuries
• Zone V
  • Area over MCP joint
  • Open injuries to this area should be considered human bites until proven otherwise
    • If it is human bite performed delayed repair following course of antibiotic
• Zone VI
  • Area over dorsum of hand
  • Tendons in this area are superficial; even minor-appearing lacs are associated with tendon injuries
  • Treatment typically requires operative fixation with K wires
• Zone VII
  • Area over the wrist
  • Repair can be difficult because of presence of extensor retinaculum
• Zone VIII
  • Area of the distal forearm
  • Tendons frequently retract into the forearm and must be retrieved and repaired
  • Lac <25%: does not require repair
  • Lac 25-50% requires simple suture repair
  • Lac >50% requires specialized repair

See Also

• Hand and Finger Diagnoses (Main)
• Tendons of the upper extremity

References

Authors

Jordan Swartz, Ross Donaldson, Neil Young, Claire, Daniel Ostermayer, Christopher Kim