Download MSK Scenarios Encountered by Generalist Sonographers

A rapidly emerging sub-specialty
 Requires dedicated training and consistent
exposure to become proficient
 That being said…

› We as general sonographers often encounter
MSK in our day-to-day exams
› This lecture will cover a few generalist exam
scenarios where some basic MSK knowledge
can go a long way in understanding the clinical
picture.
 Superficial
masses
 Achilles
Tendon
 Baker’s
cyst
 Peripheral
nerves
Our lumps and bumps exams
 Keys to assessment:

› Patient history
› Location
› Morphology
 Size
 Vascularity

Patient History:
› Clinical questions:
 How long have you had it?
 Was there an injury?
 Has it changed in size? (bigger or smaller)
 It is painful?

The answers to these questions plus the
imaging characteristics give the radiologist
an index of suspicion about a given mass
and which recommendations to make as to
follow up.

Location:
› Tissue Layers
 Skin: made up of epidermis and dermis
 Subcutaneous tissue aka hypodermis or fat
layer
 Muscle

Skin
› Thin and hyperechoic
› Lesions involving the skin layer often need
imaging with a standoff pad to optimize focal
zone and appreciate
outward mass effect
› Warts, calluses,
hemangiomas

Fat layer
› Variable in thickness
› Made up of ‘fat islands’, connective tissue,
blood vessels and lymphatic channels
› Common location
for lipomas, abcesses,
hematomas, bursitis
and ganglions.

Muscle layer
› Generally hypoechoic with echogenic fascial
lines though muscle; can become echogenic
with disuse and atrophy.
› Exhibits a striated pattern in long axis and well
formed muscle fibers are capable of
demonstrating anisotropy (change in
echogenicity based on angle of insonation)
› Masses can form a mass effect upon the
adjacent muscle or can directly invade/arise
from the muscle
 Side-to-side comparison most beneficial
 Be aware of tissue/fascial planes

Morphology:
› Sonographers are already well equipped to
describe the characteristics of any lesion they
find






Cystic vs solid
Ill-defined vs well circumscribed,
Heterogenous vs homogenous
Presence of any vascularity
Size
What can be improved upon is describing
the location of these superficial masses
› Subcutaneous vs intra-muscular
› Any invasion into surrounding tissue?
› Lipomas
 Variable in size and echogenicity (echogenic –
isoechoic)
 Most frequently subcutaneous but can also be
intra-muscular in origin
 Note should be made of lipomas that are
growing, painful and/or exhibit internal
vascularity – may need follow up
Subcutaneous
lipoma
IntraMuscular
Lipoma
› Focal fluid
 Abcess
 Hematoma
 Bursitis
 Inflammation of a bursal sac of synovial fluid
 Ganglions/Synovial cysts
 Caused by leakage of fluid from a joint or tendon sheath
into the surrounding tissue

Very similar imaging characteristics
› Often an irregular subcutaneous fluid collection
 Abscess – simple fluid or debris filled, may contain
air or exhibit increased peripheral vascularity
 Hematoma – variety of appearances depending
on stage, can look simple or solid or combined

Patient history key
› Abscess – red, inflamed skin, possible open
wound and discharge
› Hematoma – history of trauma, likely bruising
and pain over site
Subcutaneous
Hematoma
(history of injury)
Bursal sacs lie through out the body offering
cushion and protection against friction.
 Inflammation of this sac leads to excess
synovial fluid = fluid collection
 Patient history

› Pain
› Possible swelling
› Often chronic, variable in severity
Painful swelling around
the knee
- No hx of trauma
- Not a hematoma
- Not assoc w/ the joint
- Not a ganglion
Bursitis
- Most often associated with tendons/joints of the
hands and feet
- Predominately cystic, may have a thickened
rim/septations which may have increased vascularity
- Demonstrate the origin if
possible
- Often change in size
- Can be painful
› Nerve tumors
 Painful, results in numbness or tingling
 Probe pressure reproduces symptoms
 Can often be seen to directly arise from an
adjacent nerve
 Has a ‘tail’ or trumpeted ends
Nerve splaying around
the lesion
Nerve
Nerve splaying around
the lesion
Nerve
Only in long axis
can you determine
that this lesion is
arising from the
nerve
› Mysterious masses
 Asymmetric tissue layers
 Often fat but no focal lipoma
 Compare side to side to appreciate layer differences
 Muscle hernia
 Often due to a weakness or defect in the fascia
 Dynamic scanning a must
 Nothing
 Patients often palpate ‘lumps’ where there is no
corresponding abnormality – often palpating normal
muscle anatomy, etc
 Compare side to side
Patient complaint:
Lump over scapula
on left
Lump was her
scapula – more
outwardly
prominent
Herniation of
muscle thru
fascial defect
Normal
Dynamic scanning shows mass change
with muscle contraction
Patients who complained of a ‘fullness’ or asymmetry
to their back
Unable to palpate specific mass at time of exam,
panoramic reveals equal tissue planes
› Other….
 Numerous superficial mass types (benign and
cancerous) – ultrasound alone cannot distinguish
(may need MRI and/or biopsy)
 Ultrasound can start the analysis
 Solid vs. cystic
 Vascular?
 Invasive?
When in doubt:
Measure, color, clip
and give rough location
 Superficial

 Baker’s
masses
Achilles Tendon
cyst
 Peripheral
nerves

In regards to emergent requests post
trauma; Query Tear
› Often come from emergency departments and
to a lesser extent GP’s offices
Where possible these patients are being
sent to dedicated MSK centers as many
radiologists prefer to have them
performed/read by MSK specialized staff.
 However, this is not always feasible – there is
a finite surgical window to consider (7-10
days)
 These patients can’t necessarily wait to be
shuffled around and re-booked.

› Achilles used to be done under general
ultrasound before MSK became its own field
› Can and is being done under general if the
technologist is able and the radiologist is willing
› Following a few key points when evaluating the
Achilles eliminates many possible pitfalls and
results in more consistent results.

Anatomy:
Attaches the gastroc
(medial and lateral
heads) and soleus
muscles to the
calcaneus
Broad and thin
proximally at its
origin mid calf –
overlying the soleus
muscle
Thickens and becomes
fully formed distally,
inserting on the
posterior calcaneus

Key exam features
› Is there a tear?
 Evaluate the Achilles tendon in long and short axis
 Majority of traumatic tears occur between the distal
soleus and the calcaneus
 Therefore most helpful to start where its normal (the
calcaneus) and work your way up.
 A torn tendon retracts causing thickening and
heterogeneity to the torn ends (often includes
shadowing)
 Debris and hemorrhage fills the gap *will have no
normal linear strands
Normal
Achilles
Torn Achilles
Tendenotic Achilles

Key exam features
› Where is the tear?
 Measure the distance of the tear from the
calcaneous

Key exam features
› Complete or partial tear?
 Sweep side to side in long axis through the tear to
look for any residual fibers
 Take long and short axis clips through the tear to
demonstrate the changes more clearly
› Functional tests:
 Squeezing the calf = moves the proximal stump
while the distal stump remains motionless =
complete tear
 Plantar/dorsi-flex the foot = moves the distal stump
while the proximal stump remains motionless =
complete tear

Complete tear with
hematoma filling gap
Normal Long Axis
Achilles

Complete tear with
hematoma filling gap
Normal Short Axis
Achilles
Partial tear of Achilles.
Could be mistaken
for a complete tear in
long axis.

Key exam features
› Measure the tear
 Long axis most important surgically
 Can gently plantar/dorsi-flex the foot to help
define the edges of the tear
 Measure the gap in neutral and again with
plantar flexion
 Some tears are treated with a boot instead of surgery
if the tendon ends are closely approximated with
plantar flexion
 Short axis measure if tear is partial
Not everyone has one
 Lies adjacent and medial to the achilles
 Most easily identifiable in short axis by
scanning the achilles over the soleus
muscle and focusing on the medial border

› Appears as a small, separate oval structure in
the same fascial plane

PITFALL:
› An intact plantaris tendon can mimic intact
medial achilles fibers
Can be used surgically to help repair the
achilles
 Check if the patient has one

› Does it bridge the tear?
Can occur simultaneously with an
achilles tear or mimic an achilles tear by
presenting with similar symptoms
 Medial gastrocnemius most commonly
torn

› Feels like a kick or shot to the calf
› Patient has focal pain over the medial calf

Distal soleus may also be partially torn
with a high achilles tear

Anatomy
› Muscle fibers like tendon fibers should be linear
› Musculo-tendinous junctions should be sharp and
angular
› Muscles should
have thin fascial
planes separating
them
› Tears:
 Bunching and curling of muscle fibers
 Often with hematoma formation in the acute phase
*Compare to opposite side for confirmation*
 Medial gastroc
tears often involve a
fascial tear/separation
from the soleus with
hematoma tracking
up the calf between
the two muscles
› How to document:
 Image the distal musculo-tendinous junctions of
medial/lateral gastroc and soleous in both planes
*Scan through the muscle*
 Measure any hematoma formation in three planes
 Document any suspected muscle tears with static
and clip imaging
 Patient can always be rescanned at a dedicated
MSK facility if clarification is needed but finding the
problem is the first step.

the
SWEEP THROUGH
THE MUSCLE!
Long axis imaging of
medial gastroc on the
same patient
› While non-surgical, these tears can cause
significant pain and weakness causing the
patient to require a course of rest and
sometimes physio to ensure proper healing
› Missing these tears results the patient in trying to
resume activity too soon on the basis of a
normal achilles exam.
 Superficial
 Achilles

masses
Tendon
Baker’s cyst
 Peripheral
nerves
Cause of posterior knee pain and swelling
 Often found incidentally during the course
of a DVT study
 Occasionally cystic collections at the back
of the leg are not Baker’s cysts, many are
similarly benign synovial cysts of the knee
joint but rarely they can be a sarcoma
 Simple land marking of these posterior cysts
can ensure that we don’t make that missdiagnosis.

Posterior knee
anatomy

The neck of a
Baker’s cyst originates
from between the
medial gastroc muscle
and semimembanous
tendon at the medial
aspect of the post knee

tendon
And medial to
medial gastroc muscle
Originate lateral to
semimembranosus

Key exam features:
› Identify fluid collection
 Can be simple or complex
 Can be multi loculated
 Can extend superiorly or inferiorly from the
knee joint or both
› Measure in three planes
› PUT ON COLOR

Key exam features:
› Verify location
 Axial plane
 Follow the medial border of the medial
gastroc up to the knee joint
 The cyst should originate from between the medial
gastroc muscle and semimembranosus tendon
(hamstring).
› Cysts/masses in any other location must be
considered to not be Baker’s cysts
Looks like a Baker’s cyst in long
axis…..short axis reveals that it
doesn’t originate from the
proper location  synovial cyst
of post knee
3yo with a Baker’s cyst
that was compressing
his popliteal vein with
leg extension
 Superficial
masses
 Achilles
Tendon
 Baker’s
cyst

Peripheral nerves

Neurovascular bundle:
› Consist of a nerve, artery, vein and
lymphatics that travel together in the body.
› Example: brachial,
posterior tibial, etc.

Brachial neurovascular bundle
› Most problematic in terms of upper limb
venous ultrasounds to assess for clot.
› Many venous anatomical variations in the
upper limb
 Duplicated axillary vein
 Variable origin of basilic vein
 Single brachial vein

Brachial neurovascular bundle
› The median nerve also courses alongside the
brachial artery and can easily be mistaken
for a thrombosed brachial vein - especially
in a case where only one brachial vein exists.
(leading to a diagnosis of DVT where none
exists)
› This can be avoided by learning to
recognize peripheral nerves and their
locations in the body.
Are most easily recognized in cross
section
 Have a ‘pediatric ovary’ appearance by
being comprised of multiple small
hypoechoic fascicles separated by
echogenic fascia.
 These fascicles can become dilated and
therefore resemble a thrombosed vein
as they are without flow and are noncompressible.


Normal neurovascular bundle
Long axis nerve
- can be difficult to differentiate from
surrounding tissue
- can still appreciate echogenic fascia
separating the fascicles – more uniform than a
thrombosis


Thickened hypoechoic nerve (on the right) adj.
to an artery (veins compressed in this view)
Nerve would not show flow – could be
mistaken for a thrombosed vein
Nerve or Vein?
Basilic Vein
Brachial V
Test Time…
Brachial A
Basilic Vein
Median Nerve
Brachial V
Brachial A
Look for the ‘ovary’, try scanning up and down the
upper arm – no matter the venous configuration,
Every person will have a median nerve