Digital tendon sheath lacerations can lead to a septic tendon sheath if the laceration communicates with the sheath. A septic tendon sheath is very painful and has a guarded prognosis. It is important to diagnose digital tendon sheath lacerations early through knowledge of anatomy and checking for fluid communication, in order to provide appropriate treatment and the best chance of recovery. The digital tendon sheath is a thin-walled synovial structure that surrounds the superficial and deep digital flexor tendons from the distal third of the metacarpus to the distal phalanx.

1. Digital Tendon Sheath
Lacerations

2. Digital Tendon Sheath Lacerations
• Lacerations that enter
the digital tendon
sheath= Septic tendon
sheath
• Septic tendon sheath
– Very painful
– Guarded prognosis
– Best chance with early
diagnosis and
appropriate treatment

3. How Do I Know if a Laceration Enters the Digital
Tendon Sheath ????

4. • How Do I Know if a Laceration Enters the
Digital Tendon Sheath ????
– Knowledge of anatomy- index of suspicion – (link to
anatomy slides and saggital section video)
– Checking for communication between the
laceration and digital tendon sheath by fluid
distension (link to video of checking for synovial structure involvement)

5. Digital Synovial Sheath Anatomy
• Thin walled structure
that encompasses
the majority of the
SDFT and the entire
DDFT.

6. Digital Synovial Sheath Anatomy
• Proximal extent ~ distal
third of metacarpus
• Distal extent= T
ligament (intersection of
navicular bursa, palmar
coffin joint and digital
sheath)

7. Digital Synovial Sheath Anatomy
• Synovial structure- similar to joints and bursae
• Outer fibrous layer and inner synovial layer.
Image from Moyer et al Equine Joint Injection and Regional Anesthesia

8. Digital Synovial Sheath Function
• Decreases build up of friction and heat as
tendons change direction around the palmar
aspect of the fetlock and glide along side each
other