UT 505 Quiz 1 Study Guide

UT 505 - MSK

What types of TDRs are used for MSK exams?

• “Hockey stick” TDR

• L12 MHz

Long axis (LAX)

Longest plane of longest anatomy

Short axis (SAX)

Shortest axis of longest anatomy

Anisotropy

• Structure appears differently depending on the angle of insonation

  • Greatly affects tendons → can make normal tendon look pathogenic

Isotropy

Uniformity in all orientations

Articular surface

Two bones forming a joint opposite one another

Joint capsule

Fibrous tissue encompassing a joint

Abduction

Moving away from the midline

Adduction

Moving toward the midline

Floating

TDR is hovering over an abundance of acoustic gel to make “contact” while avoiding excessive pressure on structure

Enthesis

Site of attachment of a ligament or muscle to bone

Retinaculum

Band-like structure that binds tissue or organs to hold them in place

Muscle

Expands and contracts to create motion

3 types of muscles

• Smooth (involuntary) 

• Cardiac striated

• Skeletal striated

Appearance of muscles on US

• LAX

  • Homogeneous with multiple parallel echoes

  • “Feather” appearance - striated pennate appearance

  • Hypoechoic muscle fibers arranged in columns interspersed by hyperechoic fibroadipose tissue

• SAX

  • Homogeneous with punctuate echoes

Muscle pathology that can be seen on US

• Contusion/hematoma/tear

• Masses 

Ligament

• Attaches bone to bone, provides stability and strength, and aids in load distribution

• Collagen fibers arranged in basket-weave pattern

US appearance of ligaments

• Hyperechoic linear bands

  • Less prominent bands than tendons

• No muscle component

Bursa

• Synovial-lined pouches located at high friction joints

• Aids in reducing friction between tendons/muscles and opposing structures

• Potential space containing 1-3 mm of synovial fluid

Types of cartilage

• Fibrocartilage

• Articular cartilage

Fibrocartilage

• Found in the menisci (knee) and intervertebral disc spaces (back)

  • Function - shock absorption

• Appearance - homogeneous and medium echogenicity

Articular cartilage

• Found at terminal ends of bone at joints

• Adheres to bone surface

• Controls articular joint fluid level

• Function - minimizes friction and aids in weight distribution and compression

Articular cartilage US appearance

Hypoechoic noncompressible layer in contact with bone surface

US appearance of subcutaneous fat

Heterogeneous with hypoechoic fat lobules

Subcutaneous fat pads

• Location: articular surfaces where bone contacts adjacent bone surface

  • Ex: Hoffa fat pad at knee, Kager’s fat pad at heel

• US appearance: hyperechoic and homogeneous

Bone

• Most fundamental landmark when scanning

• Attachment site for tendons, cartilage, ligaments, and joint capsules

US appearance of bone

• Non-articular - sharp distinct hyperechoic line (bright reflector)

• Articular - covered by cartilage (hypoechoic)

• Should be smooth surface

  • Large gap may mean a break

  • Small gap is likely a nutrient channel

Tendon

• Extension of muscles that attaches muscle to bone

  • Function - aid flexion and extension through lever mechanism

• US appearance depends on insonation angle

  • > 10 degree off perpendicular → loss or lowering of echogenicity → false appearance of tendon pathology

US appearance of tendons

• LAX

  • Linear band of hyperechoic strands and fibrillar pattern, interspersed with relatively hypoechoic connective tissue

• SAX

  • “Whisk-broom” appearance

  • Hyperechoic foci throughout tendon distribution interspersed by hypoechoic connective tissue

  • Must maintain uniform thickness throughout except at site of insertion (might broaden)

Tendon pathology

• Tendinopathy

• Tendinosis

• Tendinitis

• Tenosynovitis

Tendinopathy

Generalized term for chronic tendon issues

Tendinosis

Progressive degeneration of tendon tissues → fraying/damage to tissue → tendon thickening

Tendinitis

Tendon-related pain and symptoms associated with inflammation → increased vascularity 

Tenosynovitis

Inflammation of sheath surrounding tendon → presents as fluid accumulation around tendon

Nerves

• Sensory and motor function by sending information throughout body

• Bundle of nerve fibers - fascicle

Nerve appearance on US

• Nerve fiber enclosed by hyperechoic epineurium 

• LAX

  • “Railroad” or “tram track”

  • Hypoechoic nerve fibers divided by hyperechoic perineurium

• SAX

  • “Honeycomb” pattern

  • Hypoechoic nerve fibers surrounded by hyperechoic perineurium

Achilles tendon

• Strongest and thickest tendon in the body

• Attachments 

  • Proximal - gastrocnemius and soleus muscles

  • Distal - calcaneus (heel bone)

Normal US appearance of Achilles tendon

Common Achilles tendon pathology

• Tendinopathy

• Partial or complete tears

• Retrocalcaneal bursitis

Partial or complete Achilles tendon tears

Retrocalcaneal bursitis