Flexor tendon injuries

Question 1

what is the Leddy and packer classification?

Answer 1

1. Tendon end in palm - rupture of vinculae - BS disruption
2. Tendon held at PIPJ level by long vinculus - BS moderately disrupted
3. Bony avulsion - held at A4 pulley
4. Profundus avulsed off bony fragment - goes to palm - double avulsion - smith modification

Mechanism of injury
- forced hyperextension of actively flexed DIPJ

Question 2

What stops the tendon going into the palm in FDP avulsions?

Answer 2

• pulleys
• vinaeculae

Question 3

how would you treat a delayed presentation of an FDP avulsion gone to the palm?

Answer 3

Key determinant:
flexible vs stiff DIPJ

• flexible DIPJ - 2 stage
• stiff DIPJ - DIPJ arthrodesis

Question 4

management of acute FDP avulsions?

Answer 4

Goal of surgery
- restore flexion at DIPJ
- ensure correct tension and gliding of tendon

Operative management
- Volar brunner incision
- identify avulsed tendon and site core suture early
- pass FDP between FDS slips
- deliver through pulley system to foot print
- minimal handling

Pulleys
- vent, fully release A3, preserve A2 or A4 to stop bowstringing

Bone anchoring
- 2 x hollow needles through phalanx
- tie suture over front of nail with button

Rehabilitation
- early range of motion
- reduce adhesions

Question 5

complications of FDP avulsions?

Answer 5

Lumbrical plus finger
- origin of lumbricals on FDP
- lumbricals - flex MCPJ and extend IPJs
- origin of lumbrical migrates proximally - intrinsic tightness - applies an extension moment at IPJs
- finger extends when trying to flex

Quadregia effect
- FDP common muscle belly
- operated finger repaired too tight
- making a fist - operated finger contacts palm first, other fingers are unable to achieve maximal flexion

Question 6

What is the anatomy of the flexor mechanism to the ring finger?

Answer 6

FDP
- originates from common muscle belly on the ulna and interosseous membrane
- inserts on base of distal phalanx

FDS
- origin from the medial elbow and radius
- each tendon has it’s own muscle belly
- inserts into the base of middle phalanx

Camper’s chiasm
FDP passes from deep to superficial through the two slips of FDS at camper’s chiasm

Innervation
- Median nerve (AIN) - all FDS and 2 radial FDP
- Ulnar nerve - ulnar FDPs