Causes / typical injury mechanism:

• Volar lacerations over the wrist, palm, and individual digits. Penetrating hand trauma represents 10% of all emergency department (ED) visits, with soft tissue defects comprising over 80% of all hand injuries presenting to the ED.
• These types of injuries often involve the tendons of the hand and wrist. The main flexors of the hand are the flexor digitorum superficialis (FDS), flexor digitorum profundus (FDP), and flexor pollicis longus (FPL).
• Disruption of the tendons, either partial or full lacerations, ultimately results in flexion deficits in the digits and wrist.

Classic history and presentation: Patients present with varying types of obvious traumatic injuries, from small, single digit lacerations to much larger injuries spanning multiple digits, the palm, or wrist. They may endorse numbness or weakness in particular portions of the hand, or loss of normal flexion cascade of the hand.

Prevalence:

• Age – The highest incidence is in patients aged 20-30 years.
• Sex / gender – Injuries of this nature are more common in males than females.

Classification system: Injuries may be classified based on the flexor tendon zones I-V that progress from the distal fingertips (I) to the proximal wrist (V).

• Zone I: Jersey finger. Distal to the insertion of the FDS.
• Zone II: From the FDS insertion on the middle phalanx to the proximal portion of the A1 pulley. "No man's land."
• Zone III: In the palm from the A1 pulley to the distal portion of the transverse carpal ligament.
• Zone IV: Injury within the carpal tunnel.
• Zone V: Carpal tunnel to the forearm. This location has the highest incidence of neurovascular injury.