Hematoma, Septic Joint, Infections, Lesions, and Masses (Lecture 5b)

What does 'equivocal' mean?

open to more than one interpretation; ambiguous

- term used when an imaging modality could not diagnose or rule out a pathology

Where are intramuscular hematomas most likely to occur?

MTJ

What does a intramuscular hematoma look like sonographically? (HINT: 3)

- Hypoechoic fluid that can become septated/complex depending on age of hematoma

- During healing, may form scar tissue or myositis ossificans = echogenic

TRUE or FALSE: Ossifications are more common than scar tissue to form after an intramuscular hematoma.

FALSE: SCAR TISSUE is MORE common than ossifications to form after a hematoma.

What is heterotopic ossification?

Bone formation in location other than bone

- ex. occurs when body send healing factors to hematoma, causing osteoblasts to dissolve blood and deposit calcium

What is the difference between an intratendinous or extratendinous tear?

- INTRA = within a tendon

- EXTRA = outside of tendon

What is the difference between primary and secondary synovitis?

- Primary = occurs due to chronic overuse, friction, or underlying inflammatory process

- Secondary = occurs due to trauma, injection, foreign body, infection elsewhere in the body, or RA

TRUE or FALSE: Synovitis increases production of synovial fluid.

TRUE

What is a septic joint?

infection of the joint (reactive synovitis within a joint)

How do you tell the difference between a septic joint and joint effusion?

1. Clinical hx

- If pt presents with infection-like symptoms = septic joint

- Septic joint presents with more pain than joint effusion

2. U/S

- Inc fluid in synovium = septic joint

- Septic joint = hyperemic

- Joint effusion = no vasc

TRUE or FALSE: Septic joints affect bone.

TRUE: Inflammation/pathogens can degrade the smooth cortex of bone, causing cortical irregularities (like acid slowly wearing down bone). Once the outer layer of compact bone is compromised, it can spread to the underlying spongy bone.

What is osteomyleitis? What are its causes? (HINT: 3) What is its sonographic appearance?

- Infection of bone

Causes:

- Trauma

- Foreign objects

- Hematogenic spread (spread thru bloodstream)

SF: (preferred imaging is w/ MRI)

- Erosion of cortex

- Coritcal irregularities

- Possible localized abscess

What is inflammatory myositis? What are its causes? (HINT: 3) What are its SF?

Infection of muscle tissue

Causes:

- Trauma

- Iatrogenic

- Hematogenic spread (spread thru bloodstream)

SF:

- Diffusely echogenic muscle tissue

- Possible atrophy

What is the CP and SF of abscesses?

- CP: infection-like symptoms (local or diffuse)

- SF: complex/mixed appearance w/ echogenic wall

What do lipomas appear as sonographically? (HINT: 2)

- Usually echogenic, but can be isoechoic

- Low to no flow

What are the SF for peripheral nerve sheath tumours (Schwannoma)?

- Continuous w/ nerve sheath but come off one side (asymmetry)

- May have flow w/ Doppler

What are the SF for ganglions?

- Cystic appearance (small outpouching of synovium from joint space)

- Round/irregular shape

- Look for tail/connection to joint space

How can you differentiate between a paralabral cyst and effusion?

- Paralabral cyst = NO movement w/ dynamic assessment

- Effusion = fluid MOVES during dynamic assessment

TRUE or FALSE: Paralabral cysts demonstrate flow, allowing differentiation to an effusion.

FALSE: Paralabral cysts and efffusion DON'T demonstrate flow w/ Doppler. Therefore, the main way to differentiate them is to perform a dynamic assessment. If there is movement, it is an effusion. If not, it is most likely a paralabral cyst.