Flexor Tendon Injuries Flashcards
Tendon composed of
70% Water
30% Dry mass - tenocytes and EC matrix (mainly collagen)
Collagen allows for
tensile strength and loading strength
How many tendons from forearm to hand?
9 flexor tendons
How many wrist flexors?
2 flexor tendons
Why is the flexor digitorum superficialis named vs flexor digitorum profundus
The muscle belly of the FDS is superficial to the FDP in the forearm
Where does the FDS split into two slips?
Metacarpal phalangeal joint
Where does the FDS attach?
Middle phalanx
Where does the FDP attach?
Distal phalanx
What is Camper’s chiasm?
Where FDS decussates/intersects around the FDP
What is the function of the pulley system?
Holds the flexor tendons down and prevents bowstringing when flexion occurs to allow for improved flexion.
What does a pulley stand for?
Annular pulley
How many A pulleys?
A1-A5
How are pulleys labeled?
Proximal to distal
What is the blood supply to the flexor tendons of the finger?
Relatively avascular, but receive blood from digital arteries dorsal blood supply to tendons
1) Branch to long vinculum (proximal)
2) Branch to short vinculum (distal)
Retinaculums also provide blood supply
What are the layers of the tendon sheaths?
Visceral
Parietal
How does the tendon receive its nutritional supply?
Synovial sheath, not directly from blood supply
How does the tendon receive its nutritional supply?
Some from the blood supply from vincular circulation
Synovial sheath and synovial fluid
Which flexor tendon does not have a vincular blood supply network?
Flexor Pollicis Longus - meaning that it can tolerate more advancement without disturbing blood supply
How many flexor tendon injury zones are there?
Zone 1-5
What constitutes Zone 1 for flexor tendon injury?
Distal to flexor digitorum superficialis tendon insertion
What constitutes Zone 2 for flexor tendon injury?
Fibrosseous tunnel, A1 pulley through Zone 1
What constitutes Zone 3 for flexor tendon injury?
Carpal tunel to A1 pulley
What constitutes Zone 4 for flexor tendon injury?
Carpal Tunnel
What constitutes Zone 5 for flexor tendon injury?
Proximal to Carpal tunnel
What do you call a Flexor Digitorum Profundus tendon avulsion and where does the avulsion occur?
Jersey finger
From the distal phalanx
Name the levels of Jersey finger and where they occur?
Zone 1/Type 1: Tendon retraction into the palm
Zone 2/Type 2: Tendon retraction to the PIP level
Zone 3/Type 3: large bony fragment blocks proximal retraction of FDP at A4 pulley
What is considered no man’s land with Jersey Finger tendon injury?
Zone 2/Type 2
What type of injury causes jersey finger?
Forced hyperextension usually from a flexed position
How many flexor tendons are there of the thumb?
Only one
Flexor pollicis longus
Which annular pulleys cover/cross joints?
A1, A3, A5
MCP, PIP and DIP respectively
How many cruciate pulleys?
C1-C3
Which pulleys are the most important for proper flexion tendon function?
A2 and A4
A2 and A4 proximal and middle phalanx
What is unique about the thumb pulley system?
Thumb only has 2 annular pulleys (A1 and A2) and an oblique pulley
Why is it recommended to theoretically repair flexor tendons volarly instead of dorsally?
Vincula blood supplies tendon on the dorsal aspect
What is considered no man’s land?
Zone 2 (A1 pulley to FDS)
When assessing for flexor FDS tendon injuries, why do you need to hold down the other fingers?
Because FDS tendons all share the same muscle belly
