Tendons are made up of collagen fibres arranged in bundles or fascicles. The main collagen fibre type is type I. Surrounding them is a CT sheath where BV, nerves and lymphatics are found.
Describe the arrangement of collagen fibrils in a tendon
Collagen fibrils follow a zig zag waveform in a longitudinal orientation known as a crimp. This helps tendons to stretch.
What are fibroblasts within tendons called?
Tenocytes
How are tenocytes arranged in tendons?
They are aligned in longitudinal rows alongside the collagen fibrils
What is the function of tenocytes?
They respond to mechanical signals and synthesise/degrade all of the collagenous and non collagenous matrix
How are tenocytes connected to each other?
By gap junctions
What is one of the most common injuries in racing thoroughbreds?
SDFT injury
What is micro damage?
The accumulation of subclinical changes to the tendon at the microscopic level
True or false: the accumulation of micro damage is being accelerated in younger horses with the use of high intensity exercise?
True
What exercise associated factors are thought to cause death or dysfunction of tenocyes?
Mechanical overload, hyperthermia, hypoxia and stress deprivation
Why will the loss of tenocytes result in poor tendon healing?
As the tenocytes are responsible for tendon repair
How does the SDFT act as an energy storing tendon?
By converting both potential and kinetic energy into elastic energy
What is the failing point of a tendon?
The more force you apply the more the tendon will stretch. Eventually you can apply so much force that the tendon will just snap - this is the failing point.
Describe why hyperthermia occurs in the tendon core and why it can cause tenocyte death
Heat is inefficiently dissipated within the tendon core due to its poor vascular supply. Gap junctions are known to spread 'death messengers' between tenocyte cells.
What are the three phases in tendon injury
Actue (inflammatory)phase , subacute (proliferation) phase and chronic (remodelling and maturation) phase
What gross changes can be seen in a tendon during the acute, subacute and chronic stages?
