TRAIN CERTIFY MAINTAIN

Acute Care Musculoskeletal (AC MSK)

CURRICULUM

Advanced skills for certification

a. Probe

Linear probe or high frequency probe of choice (10 MHz or more).

b. Knobology

i. Preset. MSK or small parts.

ii. Depth. Start at 5 cm. Adjust as needed.

iii. Gain. Initially set at mid-range. Adjust as needed.

c. Patient positioning

Patient seated with elbow flexed at 90 degrees with forearm gently resting on patient’s lap or on examination table.

d. Probe orientation

Sagittal (indicator towards patient’s head) and transverse plane (indicator towards operator’s left).

e. Probe grip

Pencil grip.

a. External landmark

Distal humerus.

b. Internal landmark

Olecranon fossa.

c. Relevant anatomy

Distal humerus, Triceps brachii muscle and tendon, Olecranon fossa, Posterior fat pad, Olecranon, Olecranon bursa, Medial and lateral epicondyles in short axis.

d. Area of interest

Olecranon fossa.

e. Adequate view

i. Long axis: olecranon fossa centred, hyperechoic and well-defined cortices of humerus and olecranon.

ii. Short axis: olecranon fossa centred. Hyperechoic and well-defined medial and lateral epicondyle.

a. Image generation

i. Landmark

  1. Start scan in the midline of posterior humerus in the sagittal plane.
  2. Slide distally until olecranon fossa visualized.
  3. End scan with sweep of olecranon fossa.

ii. Optimize image

  1. Adjust depth to centre image.
  2. Increase probe frequency to increase image resolution.

iii. Technique

  1. This is a POSTERIOR scan!
  2. Start scan in the midline of posterior humerus in the sagittal plane.
  3. Centre the humerus by sliding side to side.
  4. Sweep side to side until humeral cortex appears well-defined (thin and bright white).

  5. Slide distally until the V-shape of the olecranon fossa is seen.
  6. Centre olecranon fossa on screen.
  7. Sweep and slide lateral to medial to assess for presence of an effusion in the AOI.
  8. Turn probe 90 degrees in transverse plane with marker towards operator’s left.
  9. Centre olecranon fossa on screen.
  10. Sweep cephalad to caudad or rock probe to make medial and lateral epicondyle appear well-defined.
  11. Sweep and slide through AOI to assess for presence of effusion.

iv. Interrogate AOI

  1. Sweep and slide through AOI in LAX and SAX.

b. Image interpretation

The following areas should be evaluated and a binary yes/no conclusion made:

i. Elbow effusion? (YES/NO).

a. If unsure where is humeral cortex in LAX, rotate probe in SAX to confirm.

b. Decrease depth to centre and increase probe frequency to increase resolution.

a. Technique

i. Keep probe steady and perpendicular to the skin.

ii. Effusions can be harder to see if elbow not flexed at 90 degrees.

iii. NERD ALERT! If olecranon bursitis is suspected: extend elbow and use a thick layer of gel to float the probe and avoid compression and displacement of bursal fluid.

b. Image interpretation

i. Causes of elbow effusion cannot be assessed on ultrasound imaging alone. Clinical suspicion remains paramount. Certain fluid characteristics paired with clinical correlation can help with assessment but arthrocentesis (under US-guidance) remains warranted in most cases of septic joint suspicion.
  1. Simple synovial fluid: anechoic.
  2. Complex fluid (hemorrhage or infection): can vary from hypoechoic to hyperechoic with or without debris.
  3. Synovial hypertrophy: hyperechoic.
  4. Joint recess compressibility, redistribution of joint recess content with movement and lack of internal flow on color doppler suggest complex fluid rather than synovial hypertrophy.

ii. The hypoechoic trochlear and capitellum hyaline cartilages can be mistaken for fluid. Remember that cartilage hugs and follows the bone contours and there is no posterior fat pad displacement in the AOI because no effusion is present.

iii. If in doubt, compare with unaffected side.

c. Clinical integration

i. X-rays can miss elbow fractures. In the right clinical context in adults, posterior displacement of hyperechoic fat pad on ultrasound indicates an elbow fracture (most commonly radial head). In pediatrics, posterior displacement of hyperechoic fat pad on ultrasound indicates an elbow fracture (most commonly supracondylar).

ii. Look for effusion in trauma and in painful, red, and swollen joints.

a. Use lots of gel to float probe to limit applied pressure to tender areas.

b. Have flexed elbow resting on a pillow or rolled towels to avoid having elbow unsupported and dangling.

c. PROCEDURAL POCUS: US-guided arthrocentesis of the elbow joint:

i. Rotate probe in transverse plane to avoid triceps brachii tendon in the midline.

ii. Bring biggest pocket of fluid closer to predicted needle entry on screen (better when less travel between needle and target).

iii. We suggest an in-line approach with a needle entry lateral to medial (to avoid neurovascular structures on the medial side).

iv. Remember to avoid triceps brachii tendon by choosing a needle trajectory passing underneath it.

v. EXTRA TIP! For your comfort and easy maneuvering (if patient can tolerate the position), have patient prone on stretcher with affected shoulder ABducted 90 degrees AND elbow flexed 90 degrees.

a. For a negative scan:

i. AOI must be centred and bony cortices of surrounding bones must be well-defined in 2 planes.

ii. AOI must be interrogated looking for an effusion and lack of posterior fat pad displacement in 2 planes.

iii. No pathology is found.

b. For a positive scan:

i. AOI must be centred and bony cortices of surrounding bones must be well-defined in 2 planes.

ii. AOI must be interrogated looking for an effusion and lack of posterior fat pad displacement in 2 planes.

iii. An effusion and/or a posterior fat pad displacement is found.

Document as per CPoCUS guidelines for positives and negatives according to clinical indications:

a. Elbow joint effusion         + or –

b. Indeterminate

Prerequisites

Appropriate didactic and practical introduction to technique that must include written materials covering all relevant ultrasound physics, anatomy and theory, a minimum of 30 minutes of live or on-line lectures, and at least 5 introductory proctored elbow (olecranon fossa) scans.

The introductory scans do not count towards certification and do not need to be determinate.

Logged scan requirements

  • 5 elbow (olecranon fossa) determinate scans supervised directly by a CPoCUS MSK Track Instructor for the entirety of the scan.
  • Determinate scans are defined in ‘Determinate scan requirements’.
  • A minimum of x scans (to be determined) must be done ‘unassisted’.
  • An unassisted scan is one in which the learner generates a determinate image and uses appropriate troubleshooting maneuvers without any assistance (verbal or physical) from the instructor.
  • There is no requirement for a minimum number of positive scans.
  • All scans must be recorded in a CPoCUS logbook.

Examinations

Pass mark on CPoCUS elbow (olecranon fossa) written, practical, and visual examinations PLUS appropriate prerequisites AND logged scans as above.

Note: Prerequisites and/or logged scan requirements may be waived if a candidate is awarded a CPoCUS Exception to Certification (see website for application details).