Tendons and their conditions Flashcards
What is a tendon? What is a ligament?
Tendons connect muscles to bones
- Allows for movement
- only stretch a bit
- transmit forces from muscles to bones
- E.g.biceps contraction the force is transmitted to the humerus and the forearm and results in elbow flexion
Ligament connect bone to bone
-maintains joint stability by preventing bones from moving apart
- have a limited stretching ability thus limit how much a joint moves, & protects against injury
What is the function of tendons?
Bind structures & keep them stable
Elastic properties allow them to store energy & release it to muscle w/ no additional work
- results in smooth movement
- Reorientation of collagen type i fibres
- Straightening of the wavy fibrils
- Sliding between adjacent collagen fibrils and fibres
Transmit the mechanical force of muscle contraction to the bones
What is the structure of tendons?
Made up of mostly collagen type 1 & proteoglycan
Parallel rows of fibroblasts (tenoblasts) are organised into microfibrils & wavy fibrils
- provide non-linear strength
- fibroblasts are spindle-shaped immature tendon cells that give rise to tenocytes. highly proliferative & involved in synthesis of collagen
- tenocytes (fibrocytes)= mature tendon cells. Responsible for turnover of maintenance of the extracellular matrix & respond to mechanical load of tendon & make adaptations.
- both reside in tendon
collagen molecules consist of polypeptide chains
- 3 chains combine together to form a densely packed helical tropocollagen molecule.
- 5 of these combined together form a microfibril.
Primary collagen fibres
consist of many collagen fibrils
- fibrils have crimpled structure
Primary fibres are bunched together into primary fibre bundles (subfasicles)
- bundle is surrounded by a sheath of connective tissue called endotenon
- allows gliding of bundles against one another during tendon movement w/ little resistance
- primary fibres have crimped waveform
Groups of primary fibre bundles form secondary fibre bundles (fasicles).
- bundle surrounded by endotenon
Multiple secondary fibre bundles form tertiary fibre bundles
- bundle surrounded by endotenon
Groups of tertiary fibre bundles form the tendon unit.
- covered in connective tissue called epitenon
- Epitenon contains nerves & blood vessels which provide neurovascular supply to tendon.
Epitenon is covered in a connective tissue layer called paratenon
- allows tendon to move against neighbouring tissues.
Tendon is attached to bone by collagenous fibres (Sharpey fibres) that continue into the matrix of the bone.
In situations where tendon require extra freedom of movement, tendon separated from surroundings by synovial sheath
Vascular supply of tendons?
Sparse
Small arterioles from adjecent muscle tissue branch
- rterioles accompanied by vein, & lymphatic vessel
- Augmeneted by small vessels from addjacent loose connective tissue
Vessels rarely pass between bone & tendon except at achilles tendon
- Receives blood supply across osteotendinous junction
Nerve supply of tendons
innervation of tendons start from cutaneous, peritendinous & muscular nerves.
Nerve fibres cross & enter endotenon & paratenon.
- These fibres then enter & innervate the epitenon.
Nerves terminate & reside on surface of the tendon.
Largely sensory
no evidence of any capacity for vasomotor control
Myelinated nerve fibers are specialized mechanoreceptors (Golgi tendon organs) sensing tension & pressure in the tendon
- located close to the muscle
Unmyelinated fibres are responsible for sensing & transmitting pain (nocioceptors)
What determines the thickness and strength of tendons?
Thickness depends on size & strength of associated muscle
AND Degree of pennation of the muscle
Tendons can adapt their strength & stiffness to match mechanical demands - but process is slow & incomplete
- Deform slowly when exposed to external force
- Once the deforming force has been removed it returns to its original shape
- If you pull fast - snaps
- If you pull slow - stretches
How do muscles insert into bones?
Enthesis/Osteotendinous junctions = where bone & tendon meet
- Can be Fibrocartilaginous or fibrous
Fibrocartilaginous:
- no sharp boundaries between zones
- proportions of each component vary between entheses
- usually found where a tendon approaches bone at high angle
- Found at attachment of tendon to metaphysis or diaphysis
Fibrous Entheses
- found on shafts of long bones, & small bones of hands & feet
- tendon approaches bone at acute angle & merges at periosteum
- connects w/ dense fibrous conective tissue
- attach to greater area of bone compared to fibrocartilaginous entheses
What are the three main pathologies that affect tendons?
- tendinopathy- injury to tendon or overuse
- Or specifically enthesitis- inflammation of enthsis - tenosynovitis- Inflammation of synovial lining of the tendon sheath
- tendon rupture
Others:
- Tendonitis= inflammation of tendon
- Tendinosis= chronic degeneration of tendon without inflammation, due to failed healing of repeated minor injuries
Pathophysiology of Tendinopathy
Occurs as part of systemic inflammatory condition
Due to injury/overuse
Idiopathic
Mainly caused by
- Trauma
- Inflammatory Arthritis
Presentation of tendinopathy/ enthesitis
Pain
- Worse on active movement
- increased when active movement is performed against resistance
Tenderness at ethesis
Rubor, calor, dolor, tumor
Soft tissue swelling - not always present
Investigations for enthesitis
X ray - may see clacifiation at enthesis
Ultrasound scan - may see oedema, calcification, tears
MRI - - may see oedema, calcification, partial thickness tears
Give examples of tendiopathy/ enthesitis and their clinical presentation
Tennis elbow
- i.e. lateral epicondylitis
- inflammation of tendons & forearm muscles due to overuse i.e. playing tennis
- muscles & tenon responsible for extension of wrist & finger
- Most common tendon injured =
extensor carpi radialis brevis i.e. at common extensor region
- Pain + tenderness + stiffness + weakness + tingling
- pain on resisted extension
Golfer elbow
- i.e. medial epicondylitis
- less common
- inflammation of tendon due to overuse- flexion of wrist
- Pain + tenderness + stiffness + weakness + tingling
- Most common injured = flexor carpi radialis & pronator teres i.e. at common flexion region
- pain on resisted flexion
Jumpers knee
- i.e. patella tendinitis
- Pain at inferior pole of patella
or can also be at insertion of quads
- Overuse of patella tendon e.g. when jumping or running constant stress
- patella tendon role= extension of leg
- pain (when straightening leg or bending) + tenderness + swollen knee + stiffness
- different to Osgood Schlatter
Rotator cuff- specifically supraspinatus tendonitis
- caused by overload of rotator cuff tendon- due to repeated overhead activities e.g. weight lifting, swimming, tennis
- In subacromial space
- When subacromial space becomes narrowed = supraspinatus irritation
- area of poor blood supply
- Angiogenesis can occur whilst attempting to repair- causes congestion & pain
- pain at greater tuberosity+ pain radiates up neck & down deltoid + stiffness + inflammation + loss of strength
- Painful arc + weak shoulder abductions + drop arm sign
Achillies tendonitis:
- achilles attaches gastrocnemius & soleus to calcaneus
- Help go on tip toes
- injury due to inability to adapt to strain & overuse e.g. running & football
- Pain + morning stiffness
Bicep tendonitis
How is tendinopathy managed?
RICE
Avoid applying pressure
NSAID
Physio
Analgesics - paracetamol
NSAIDs
Local corticosteroid injection
Surgery
What is Osgood Schlatter disease?
Osgood Schlatter:
- occurs in children
- during contact sport e.g. rugby
- inflammation & irritation of patella tendon where it attaches to the growth plate of tibia
- As quadricep muscle stretches, it pulls on patellar tendon
- Repeated tension & irritation causes pain, swelling, inflammation, & formation of bump right below knee
Different to patella tendonitis:
- irritation originating where patella inserts onto growth plate of knees- Osgood-Schlatter
- Injury to patellar tendon- occurs slightly higher that OS- patella tendinitis
What are the main causes of tenosynovitis?
Inflammatory arthritis
Trauma
-Result of repetitive or
- unaccustomed movement
