Week 2 Muscle, Tendon & Nerve Pathology

Question 1

Briefly describe 3 types of muscle trauma and ultrasound appearances

Answer 1

1. Direct / crack injury: Haematoma, town fascia, scar tissue periphery then central, tear, discontinuous fibres, hypoechoic gap, echogenic debris in tear, shaggy margins
2. Indirect / stretch: tear occurs when tension applied to the muscle the is more than the forces the muscle can withstand. MTJ weakest part. Partial or complete year
3. Myositis ossification (HBF): this is a complication of a muscle tear. Can occur after an intramuscular haematoma, which May calcify and therefore ossify.
   HBF is tissue inflammation and bone ossification and can develop with no trauma for example arthroplasty

Question 2

Brevity describe 3 types of intramuscular turnouts

Answer 2

1. Malignancy tumours: fibrous histiocytoma. Rare but most common type of MSK and accounts for less than 1% all carcinomas. Is hypoechoic, unioculated with increased vascularity
2. Cysts: rare, conforms to the normal characteristics of cysts found elsewhere in the body
3. Angioma: is a relatively common soft tissue mass that can appear either hypoechoic or hyperechoic, uni or multioculated and can change in response to muscle contraction and exercise

Question 3

Compare tendinosis and Tendinopathy

Answer 3

Tendinosis: specifically related to degenerative condition caused by microscopy changes in collage eg repeative stress, without inflammation

Tendinopathy: is a broader term and includes a range of tend related pathologies including tendinosis but not limited to only degenerative. Can be degenerative and inflammatory

Question 4

List the 4 stages of tendinosis and briefly describe

Answer 4

1. Early stage: mild to no ultrasound change
2. Reactive stage: hyp/anaechoic areas due to increased water content or mucous degeneration, mild swelling, increased vascularity due to early response to trauma
3. Tendon dysrepair: increased thickness, disorganisation of collagen fibres
4. Degenerative stage: loss fibrilar patter, hypoechoc areas, calcification, spurs, further disorganisation

Question 5

What is enthesitis

Answer 5

Inflammatory enthesopathy
1. Dense fibrous connection tissue
2. Uncalcified Fibrocartilaginous
3. Calcified Fibrocartilage
4. Bone

Question 6

Briefly describe the 3 main focal neurallesions that can be found in MSK

Answer 6

1. Mortons neuroma: benign mass, perineural fibrosisinvolving plantar digital nerve between 2 metatarsal heads. Multiple / bilateral, develop due to friction against transverse intermetatarsal ligament, seen as ovoid hypoechoic compressible mass with fluid in intermetatarsal bursae
2. Traumatic neuroma: proliferative mass that represent a disorganised attempt at muscle regeneration, palpable endear firm lump, common in lower limbs after amputation, fibrous capsule, well defined, hypoechoi
3. Neural fibrolipoma: unknown origin, causes infiltration of perineurium and epinerieium with fibrofatty tissue, 80% include median nerve, others are ulnar or radial, thickened hypoechoic

Question 7

What is the main difference between a schwannoma and a neurobribroma

Answer 7

Schwannoma: grows eccentrically to the nerve
Neurofibroma: centrally located mass

US hard to differentiate as both are discrete homogenous ovoid hypoechoic with health nerve at proximal and distal ends

Schwannoma: - encapsulated tumours grows with axis of epineurium therefore allows surgical removal without loss of function
Neurofibroma: - commonly sporadic, diffuse or focal

Question 8

Briefly discuss nerve entrapment

Answer 8

Nerves that pass through a tunnel and is vulnerable to compression due to a variety of extrinsic causes like ganglions, synovitis, congenital, traumatic, tumours etc

Neural compression can lead to ischaemia and venous congestion and if chronic can cause fibrosis and loss of function with atrophy of muscles

Clinical history and nerve conduction test can provide diagnosis

Ultrasound: change in shape, echo texture, oedema, congestion, fibrosis, flattening

Question 9

List some important information about nerves on ultrasound

Answer 9

Compressible (unlike tendons)
Change shape depending on anatomatic space that surrounds nerve
Nerves course very close to tendons
Fasicular patternm multiple hypoechic parallel lines with hyperechoic bands

Question 10

What is a osteofibrosis tunnel

Answer 10

Narrow pathway to redirect nerves
In the absence of retinaculum, holding tendons
Can lead to possible instability, subluaxation or dislocation from the grove
Become thinner as the contents in the tunnel increases

Common places for tendon dislocation include long head biceps, peroneal,flexordigitorum

Common places for nerve dislocation include ulnar nerve at elbow

Question 11

Briefly discuss ulnar nerve osteofibrous tunnel

Answer 11

The ulnar nerve lies in an steofibrous ring in the Subiaco tunnel which is formed by the olecranon and the medial epicondyl

Question 12

What are some pathology related to osteofibrous tunnels

Answer 12

Chronic tendons against walls can lead to tenosynovitis
Tenosynovitis - pain, reduced function, triggering
Swollen, texture disarrangement, focal/diffuse thickening of synovial sheath

Question 13

Main malignant never tumour

Answer 13

Malignant peripheral nerve sheath tumor
Main signs of malignancy: >5cm, ill defined possibly due to oedema, heterogenous, central necrosis

Clinically there will be neurological symptoms, muscle atrophy

Question 14

Briefly discuss tendon anatomy

Answer 14

Dense connective tissue - densely packed collagen fibres that are arrange in parallel bundles
Peritenon is loose connective tissue that wraps around the tendon
Small tendons are generally avascular
Larger tendons are generally vascular and have lymphatics, blood and nerve endings
Tendons can attach to tuberosities, spinal, trochanters,ridges or process
Blood supply to tendons is poor and occurs through ground substance.
ground substances decreases with aging, fibres/fat increases

Question 15

Fibrous Sheath vs Synovial Sheath

Answer 15

both fibrous sheaths and synovial sheaths are protective structures that play important roles in the functioning of tendons. Fibrous sheaths provide mechanical support and reduce friction, while synovial sheaths add the additional benefit of lubrication through the production of synovial fluid, allowing for even smoother movement

Question 16

Discuss a synovial sheath in detail

Answer 16

A synovial sheath, also known as synovial tendon sheath or synovial membrane, is a specialized structure found around certain tendons, primarily in the hands and feet. Unlike the fibrous sheath, the synovial sheath is lined with a synovial membrane that produces synovial fluid. Synovial fluid is a lubricating substance that reduces friction between the tendon and its surrounding tissues during movement.

The synovial sheath allows the enclosed tendon to glide smoothly as it moves through the confined space within the sheath. This smooth movement is crucial for efficient and painless motion in areas with complex and intricate movements, such as the fingers and toes.

Larger tendonslack a synovial sheath eg patella, achillies

Question 17

Discuss a fibrous sheath in detail

Answer 17

A fibrous sheath, also known as a fibrous tendon sheath or tendon sheath, is a strong, dense, and fibrous layer that surrounds some tendons in the body. Its primary function is to protect and provide support to the enclosed tendon as it moves within it. The fibrous sheath is like a tough, flexible tube that prevents friction and reduces wear and tear on the tendon during movement.

Fibrous sheaths are commonly found in regions where tendons pass through narrow spaces or tight channels near joints. They are especially common in areas where tendons cross over bony prominences, such as the wrist and ankle. The fibrous sheath helps maintain the position of the tendon and reduces the risk of injury.

Question 18

Describe Peritendinitis

Answer 18

Inflammation of the paratenon - which is the connective tissue surrounding the tendon in the absence of a synovial sheath
It is seen in achillies
Ultrasound shows hypoechouc thickening of the paratenon with renaming tendon unaffected, increased vascularity

Question 19

Describe tenosynovitis

Answer 19

This is inflammation of the tendon sheath by tendons that are surrounded by a synovial sheath, especially in hand, wrist and ankle
Can be caused by trauma, repetitive micro trauma, pygogenic infection, foreign body
Can be see as fluid in the sheath
De Quervain - ABL or EPL thumb
Rheumatoid arthritis

Question 20

What are 2 non-articular osteochondroses onditions

Answer 20

1. Osgood Schlatter
2. Sending Larsen-Johanson

Question 21

Briefly describe Osgood-schlatter (non articular osteochondroses)

Answer 21

This is osteochondroses of the tibial tuberosity (distal insertion of patella tendon). Can be seen as swelling of anaechoic cartilage, patella tendon thickening, infrapatella bursitis

Question 22

Briefly describe Sinding Larsen-johanson (non articular osteochondroses)

Answer 22

This is osteochondroses of accessory ossification centre of the lower pole of the patella where the proximal patella origin is. This is seen as an echogenic ossification centre, swollen hypoecho cartilage/surround soft tissue

Question 23

What are some post operative tendon patterns

Answer 23

Can appear enlarged, hypoechoic, heterogenous, irregular margins, internal linear echoes that may appear shorter
Difficult to differentiate post op changed from a tear/tendinitis

Question 24

Brevity discuss a bakers cyst

Answer 24

This is a cyst adjacent to the posterior knee joint.
It is caused by abnormal distension of gastrocnemiosemembraneous bursa which communicates with the posterior knee joint (posterioromedially)
It is often seen in conditions that increased intra articular pressure through overproduction of synovium.
A ruptured bakers cyst can mimic thrombophlebitis and can be filled with pannus - which mimics a solid mass