TENDON INJURIES Horses

Question 1

Explain the structure and function of the SDFT

Answer 1

FUNCTION:

SDFT and SL;

• reduces hyptoension of the fetlock joint
• springs to store and release energy during stretching
• main energy storing structures

Question 2

explain the structure and function of tendons

Answer 2

Structure

Specialised molecular composition –> high strength structure Dense fibrous ECM - High water content - Collagen I predominant - Non-collagenous proteins (GAG, COMP)

Function

• Postion limb durring locomotion
• Viscoelastic properties
• Max stress = tendon rupture

Question 3

describe collagen

Answer 3

Hierachical Struture, fibrils orientated in direction of force application

• collagen molecules stabilised by chemical crosslinks, hgih tensile strength

Question 4

Draw a tendon.

(learn this diagram..)

Answer 4

should look like this

Question 5

describe two non-collagenous proteins

Answer 5

1. Proteoglycans
   - regulate fibrillogensis
   - organise matrix
2. Glycoproteins
   - COMP most abundant; older horses tend to have a lower amound of COMP hench wby there is a higher rate of tendon injuries in older horses.

Question 6

explain tendon/ ligament epidemiology

Answer 6

most common cause of MSI (muscle skeltal injury)

• 46% of all MSI involve ligamets/tendons
• SDFT most commonly injured

risk of injury increses with

• increased age
• increased speed
• male horses

Question 7

what are the two ways tendon injury occurs?

Answer 7

occurs in one ot two ways:

1. overstrain injury (most common)
2. Truma

Question 8

explain the mechanisms of overstrain injury

Answer 8

1. accumulation of microdamage overtime
   - increased MMP gene expression
   - limited ability to repair
2. increased age
   - reduced crimp; reduces strain needed to cause damage
   - reduced tendon fascicle sliding
3. Hysteresis
   - temperature within core of tendon, recent evidence suggests increased pro-inflammatory mediators greater then 45 celsius
4. muscle fatigue
   - most tendon injuries occur later in the race
   - muscle fatigue late in race leads to abnormal loading
   - DDFT fatigue; destabilisation of fetlock joint
   - never been followed up in studies if this is true.

Question 9

List and describe methods for diagnosis

Answer 9

1. Clinical examination
   - palpation
   - lameness examination; but horse may only appear lame for a couple of days following injury and then be sound
2. Ultrasound examination
   - appearance varies depending of severity of lesion

Question 10

list and describe rehabilitation programs

Answer 10

1. Initial treatment
   - reduce inflammation; ice/cold water hosing, bandaging, NSAIDs, confinement
2. Excercise programs
   - uncontrolled excercise; not a good option, tendons will not be conditioned and re-injury rate is high
   - controlled excercise; accompanied by regular ultrasounds, still about 50% re-injury when returned to racing
3. surgical management
   - not done too often these days
4. intralesional therapy
   - regenerative medicine
   - stem cells, bone marrow or adipose derived
   - Platelet Rich Plasma; limited evidence that it is of any benefit
5. shockwave therapy
   - some evidence that it may be harmful not used often.