Hand Flexor Tendon Injuries

HPI: 
Approximately 30 y/o right handed male presents with a laceration to base of the left thumb and inability to move his thumb.

EXAM:
Left hand: Laceration extends along the volar base of the thumb, no other injuries noted. Thumb is held in extension with limited opposition of the thumb. Complete inability to flex the thumb at the ITP. Ability to extend the thumb is preserved. When the wrist is extended, the thumb remains in extension. Decreased two point discrimination distal to the laceration. Ability to cross 2nd and 3rd digits is preserved. Remainder of sensation and motor function of the digits is intact.

IMAGES:
X-rays are needed only if underlying fracture is suspected (malalignment of digits)

MANAGEMENT
#ED Management
- Assessment for other injuries
- Thorough irrigation of wound and closure of skin
- Splint in slight flexion
- One dose of Ancef preferred
- Very close follow up with hand specialist (1-3 days)

#Non-Operative
- <60% of tendon width affected
- Wound care and hand rehab

#Operative
- >60% of tendon width affected
- Ideally within 2 weeks of injury
- Extensive hand rehab starting immediately after repair
- Lots of repair techniques available depending on zone of injury. Outside the scope of this post

DISCUSSION
- This patient had a complete FPL transection. Laceration repaired, given 2 day f/u.
- Flexor tendons need to be fixed ASAP but not emergently
- More urgency than extensor tendon repairs
- High suspicion with any volar laceration
- Outcomes very variable depending on zone of injury and time until surgery
- Hand rehabilitation is paramount to prevent scarring and loss of function
- FDP inserts in the DIP. FDS inserts in the PIP.
- High probability of concomitant neurovascular injury, associated with worse outcomes
- Tenodesis effect - naturally, the digits flex when the wrist is extended. If abnormal very high likelihood of flexor tendon injury.

KEY POINTS
- High suspicion with volar lacerations and digits in extension
- Remember the tenodesis effect
- Always check for neurovascular injury
- Higher urgency than extensor tendon injuries
- Urgent but not emergent surgery required
- Can close in the ED and arrange very close hand follow up
- Splint in flexion
- Be aware of the different different zones of the hand but extensive detail not needed.

by Dr. Mohamed El-Kara

REFERENCES:
http://www.orthobullets.com/hand/6031/flexor-tendon-injuries