MSK growth/injury and repair: tendons and ligaments Flashcards
What are ligaments?
Dense bands of collagenous tissue that span a joint
They are anchored to the bone at either end and provide joint stability through range of motion.
Often they are divided into segments with slightly different orientations and that results in different portions of the ligament tensioned at different joint positions
Multiple ligaments in any one joint
What makes up ligaments?
Collagen fibres (type 1)
Fibroblasts within them
Sensory fibres for proprioception, stretch and sensation/pain - first 2 are important for the brain to know where the joint is in time and space
Vessels on surface so they when they are damaged they bleed
Crimping - allows for stretch
What’s the difference between ligaments and tendons?
Ligaments have lower % of collagen and a higher % of proteoglycans and water
Less organised collagen fibres
Rounder fibroblasts
What is one of the most common joint that gets injured in ligament injuries?
The ankle joint - especially the lateral ligament
How does a ligament rupture?
If the force put on the joint exceeds the strength of the ligament then it can rupture
Can be a complete or incomplete rupture
This is sometimes expected
but can be unexpected too (if joint is an abnormally sensitive position and the muscles aren’t contraction)
How do ligaments heal?
There is an initial haematoma and as this is resorbed it creates an inflammatory hypertrophic vascular response and its replaced with a heavy cellular infiltrate
Proliferative phase - production of scar tissue. A disorganised collagenous connective tissue is laid down
Remodelling - the disorganised tissue is put under pressure and direction. The matrix becomes more ligament like however there is always a visual scar.
Who should get conservative treatment for ligament damage?
Partial tear
Complete tear with no instability
And those who are poor candidates for surgery - liable to get more complications from attempting repair than from leaving them with ligament disruption
Who should get operative treatment for ligament damage?
Instability of the joint resulting from ligament damage
Those with a high expectation of performance from their joint (sportsmen)
Compulsory - if you damage multiple ligaments around a joint the joint will be so unstable that it will need repaired
If it can’t be repaired then there should be replacement of the ligament
What makes up tendons?
Longitudinal arrangement of cells (mostly tenocytes) and fibres (Collagen type 1)
What does endotenon cover?
Collagen bundles
What are fascicles covered by?
Paratenon
The tendon itself is covered by what?
Epitenon
How does the blood supply enter into the tendon?
Through vincula
How are tendons connected to their tendon sheath?
By vincula and this is how the blood supply enters
The vincula
What are the functions of pulleys?
They hold the tendon down to the bone
Function of tendons
Flexible and very strong in tension - they pull on bones in order to bend joints and provide propulsion
Movement is life - if they become immobile the water content and glycosaminoglycan concentration and strength reduce
Degeneration of tendons
Most commonly associated with the Achilles tendon
The tissue changes (intrasubstance mucoid degeneration). It may be swollen, painful, tender or patient may be asymptomatic.
In some cases this is a precursor to rupture of the tendon
Inflammation of tendon
Most common = Quervain’s stenosing tenovaginitis
The tendons of EPB and APL passing through common tendon sheath at radial aspect of wrist - they become swollen, tender, hot and red.
What is Enthesiopathy?
Inflammation at insertion to bone of muscle or tendon
It’s thought to be caused by repetitive action (tennis etc)
Traction apophysitis?
Apophysitis results from a traction (movement of ligament or tendons over the bone) injury to the cartilage and bony attachment of tendons in children and adolescents.
Common type is Osgood Schlatter’s disease which is seen in adolescent active boys (not seen once growth plates have closed).
This affects the insertion of patellar tendon into the anterior tibial tuberosity. There’s an inflammatory component too.
What is tendon avulsion?
When a tendon is torn off by either trauma or surgery
This happens when the load exceeds the failure strength while the muscle is contracting
Mechanisms of rupture
Pushing off with weight bearing forefoot whilst extending knee joint e.g sprint starts or jumping movements
Unexpected dorsiflexion of ankle e.g slipping into hole
Violent dorsiflexion of plantar flexed foot e.g fall from height
Treatment of tendon rupture
Conservative - splint/cast, mobilisation
Operative - for high risk rupture or individuals with very high activity
Common causes of laceration of tendons
Handling sharp objects at work or injury whilst cutting food
