Elbow normal

The techniques below demonstrates how to identify normal anatomy. Remember to assess all musculoskeletal anatomy dynamically and thoroughly.

We divide  the elbow into lateral, anterior, medial and posterior.

Transverse plane through the proximal forearm.

REF:Grays anatomy.

Patient set-up

POSITION 1:

The patient can be seated on the side of the bed in front of you.

Use a pillow under their arm for support.

When examining posterior or medial, remove the pillow and put their palm on their ipsilateral leg.

POSITION 2:

Seat the patient on the opposite side if the bed with their arm extended towards you.

Lateral Elbow

  • Common Extensor tendon.
  • Radial collateral ligament
  • Radial Nerve (Posterior Inter osseous nerve – ‘PIN’)
  • Annular ligament

common extensor tendon origin (CET)

The common extensor tendon is comprised of:

  1. Extensor carpi radialis brevis (ECRB)
  2. Extensor digitorum (ED)
  3. Extensor digiti minimi (EDM)
  4. Extensor carpi ulnaris (ECU)
lateral elbow CET anatomy AL
Anatomy of the lateral elbow and common extensor tendon origin.
Ref: anatomyLearning.com

To scan the common extensor tendon origin:

  • Patient seated with elbow flexed, forearm pronated (i.e. hand palm down).

TIP: 45-90degree flexion is ideal.

To identify the common extensor tendon origin:

  1. Palpate the lateral epicondyle of the Humerus.
  2. Place the transducer on-top of the lateral epicondyle in a longitudinal plane with the forearm (not just adjacent to it).
  3. The CEO should be now in the center of your image.
  4. Slide anteriorly and posteriorly assessing the entire tendon.

TIP: Have the 'heel' (non-marker) end of the transducer aimed at the midline of the posterior wrist.

Normal appearance:

  1. Fibrillar with a flat contour.
  2. Smooth underlying bony surface.

Once you identify the CEO:

  1. Is it fibrillar
  2. Does it have a flat contour? If it is convex, it is thickened and abnormal. If it is concave, it is torn
  3. Is it hyperaemic?
  4. Is there fluid or calcification associated with the tendon?
  5. Is there bony irregularity?

Common extensor tendon origin to the lateral humeral epicondyle. Place the probe on the lateral epicondyle with the heel of the probe aimed at the midline of the posterior wrist.

Ultrasound of a normal Common Extensor Tendon origin. (CET or CEO)

Radial Nerve (+ posterior interosseous nerve - PIN)

To scan the radial nerve:

  • Patient seated with elbow gently extended.
  • Hand semi-pronated (i.e. hand medial side down).

To identify the XXX:

  1. Place the probe 3-4cm proximal to the lateral aspect of the anterior elbow crease.
  2. You will see the radial nerve between the bracialis and brachioradialis  muscles.
  3. Follow the radial nerve distally in transverse. it will divide into the superficial and deep branches approximately at the elbow crease

TIP: Beware initially mistaking the tendon slip for the radial nerve within the muscles. Both will be echogenic. The tendon will be more linear, vertical and lateral. The nerve more rounded. 

Normal appearance:

  1. TRANSVERSE: XXXX
  2. LONGITUDINAL: XXXX

Once you identify the XXXXX:

  1. Is it ...
  2. XXXX
  3. XXX

Radial Nerve ultrasound scan plane. Place the probe 4cm proximal to the lateral aspect of the anterior elbow crease.

Ultrasound of the common Radial Nerve – normal.

Posterior interosseous nerve (PIN) ultrasound scan plane.

Ultrasound of deep branch of the Radial Nerve (Posterior interosseous nerve) – normal.

For detailed protocol on scanning the lateral elbow

Anterior Elbow

  • Anterior joint.
  • Biceps tendon
  • Median nerve

Anterior Elbow Joint

To scan the elbow joint:

  • Patient seated with their elbow gently extended.

TIP: If the elbow is hyperextended, small effusions will be compressed and not visible. 

Investigate the anterior elbow joint in 3 areas:

  1. Transverse distal humerus.
  2. Radial fossa
  3. Coronoid fossa of the humero-ulna joint.

1: Begin in a transverse plane at the distal humerus (approximately 5cm above the elbow crease.

Slide the probe distally until you visualise the curvy distal humerus lined by hypoechoic cartilage.

TIP: The most common mistake is stopping to soon when you slide down.

2. Rotate into longitudinal. Slide laterally until you visualise the radial head.

3. Slide medially until the coronoid process of the ulna is seen.

TIP: The anterior ulna is more difficult to see than the radius. The coronoid process will be a triangular point coming up towards the probe.

Normal appearance:

  1. TRANSVERSE HUMERAL CONDYLES: Anechoic cartilage of a uniform thickness,  across the distal humerus.
  2. LONGITUDINAL VIEWS: No fluid visible

Once you identify the joint recesses:

  1. Is it there any fluid?
  2. Is it simple or complex?
  3. Is there associated synovial thickening and/or hyperaemia?
  4. Is there calcification in the cartilage associated with the humeral view? Calcific deposits on the cartilage surface are likely degenerative such as osteo-arthritis. Calcification within the cartilage is chondrocalcinosis and is associated with disease.

Ultrasound scan plane of the  anterior elbow joint.

Begin transverse distal humerus and slide until to see the cartilage of the joint surface.

Ultrasound of a normal anterior elbow joint. Transverse plane at the level of the Humerus. Note the hypoechoic articular cartilage (green).

The white arrows indicate the radial and coronoid fossae where an effusion may be visualized first.

Ultrasound scan plane of the  anterior elbow joint radial fossa.

Ultrasound of the Radial fossa at the antero-lateral aspect of the elbow.

The white arrows indicates the likely position of a joint effusion

Ultrasound scan plane of the  anterior elbow joint coronoid fossa.

Ultrasound of the coronoid fossa at the antero-medial (Ulnar) aspect of the elbow.

The white arrow indicates the likely position of a joint effusion

Biceps tendon

To scan the distal biceps tendon insertion there are 2 main approaches:

(1) Direct approach

  • Patient with their elbow as extended and supinated (palm UP) as possible.

(2) Pronator window

Patient with their elbow flexed to 90degrees.

TIP: Support the patients arm with a pillow or towel.

(1) Direct approach:

  1. Place the probe transversely 2-3cm  above the elbow crease.
  2. Identify the biceps belly and follow distally to the tendon, (will lie superficially at the elbow crease).
  3. Slide distally. The biceps tendon will dive steeply and become anechoic due to anisotrophy.
  4. Slide the probe medially, whilst angling to keep the BT in view.
  5. Rotate into longitudinal. You will need to apply significant pressure with the heel of the probe to become perpendicular to the tendon.
  6. Fan through to examine both the long head and short head insertions.

(2) Pronator window:

  1. Place the probe longitudinally along the medial distal Humerus.
  2. Slide distally onto the forearm, maintaining the same plane.
  3. Fan gently anteriorly to see the Pronator belly on the brachial artery on the biceps tendon.
  4. Pronate/supinate the forearm to assess function.

TIP: Use the distal Brachial artery as a landmark and a window. It will be immediately superficial and medial to the distal tendon.

Normal appearance:

  1. TENDON: Fibrilar, echogenic, homogeneous. The distal biceps tendon should have a flat contour. Both sides of the tendon should be parallel to each other.
  2. INSERTION: There are 2 components. Gently fan the probe to visualise both.

Long head has a broader footprint on the proximal end of the radial tuberosity.

Short head biceps has a thinner, more direct insertion.

Once you identify the distal biceps tendon and insertion, assess for:

  1. Is it uniform and fibrillar.
  2. Any retraction
  3. Calcification
  4. Fluid

Mobilise the tendon by gently rotating the distal forearm.

TIP: The distal tendon is stabilised  by the bicepital aponeurosis (Lacertus Fibrosus). This is poorly seen on ultrasound however it can prevent any significant retraction of a torn tendon. So you cannot rely on  a retracted musculo-tendinous junction to diagnose a tear.

Pronator window approach to the distal biceps tendon insertion.

Ultrasound of the distal biceps using the pronator window.

Biceps tendon and median nerve at elbow crease-Transverse.

Ultrasound of Median nerve and biceps tendon in antecubital fossa.

Biceps insertion onto radial tubercle- Longitudinal scan plane.

Ultrasound of Normal Biceps tendon insertion.

Median nerve

To scan the median nerve:

  • Patient seated, elbow gently extended.
  • Palm up

To identify the median nerve at the elbow:

  1. Place the probe transversely at the elbow crease.
  2. The median nerve will be antero-medial on the pronator muscle.
  3. The nerve can be followed distally to the wrist in transverse. As you follow the nerve, it dives under the brachio-radialis muscle in the proximal forearm before returning closer to the surface.
  4. The nerve may also be readily followed proximally in transverse where it courses medially to lie between the biceps and triceps bellies.

TIP: XXXXXX 

Normal appearance of the median nerve:

  1. TRANSVERSE: Ovoid. Echogenic with multiple small hypoechoic spaces 9these represent the bundles of nerve fascicles)
  2. LONGITUDINAL: Hyperechoic and hypoechoic fibrillar pattern. Less fibrillar than a tendon.

Once you identify the median nerve:

  1. Is it uniform in thickness? Look for thickening or masses
  2. Is the echogenic rim (epineurium) thickened?
  3. Any surrounding hyperaemia?

Ultrasound scan plane of the median nerve at the antecubital fossa, just distal to the elbow crease.

Ultrasound of a normal transverse median nerve at the elbow. Note it’s relationship to the brachial artery.

Ultrasound scan plane of the median nerve at the antecubital fossa, just distal to the elbow crease.

Ultrasound of a normal longitudinal median nerve at the elbow. The nerve dives steeply, distal to the elbow crease.

For detailed protocol on scanning the anterior elbow

Medial Elbow

  • Common flexor tendon (CFT).
  • Ulna nerve
  • Ulna collateral ligament

Common Flexor Tendon origin (CFT / CFO)

The common flexor tendon is comprised of:

  1. Flexor Carpi Radialis  (FCR). One head inserts to the medial epicondyle, the 2nd to the radial shaft
  2. Palmaris longus (PL)
  3. Flexor Carpi Ulnaris (FCU). One head inserts to the medial epicondyle, the 2nd to the ulna

.

medial elbow CFT anatomy AL
Anatomy of the medial elbow and common flexor tendon origin.
Ref: anatomyLearning.com

To scan the common FLEXOR tendon origin:

  • Patient seated

Method 1

  • Elbow extended
  • Arm gently externally rotated

Method 2

  • Patient places their hand on their leg, fingers medially.
  • Elbow flexed and tilted towards you. 
  • This can give good stable access to posterior structures too.

To identify the Common Flexor tendon origin:

  1. Palpate the medial epicondyle of the Humerus.
  2. Place the transducer on-top of the medial epicondyle in a longitudinal plane with the forearm (not just adjacent to it).
  3. The CFO should be now in the center of your image.
  4. Slide anteriorly and posteriorly assessing the entire tendon.

TIP: Have the 'heel' (non-marker) end of the transducer aimed at the midline of the anterior wrist.

Normal appearance:

LONGITUDINAL:

  • Fibrillar echotexture
  • Echogenic
  • Flat or slightly convex surface
  • Smooth underlying bony contour

TIP: The CFT is shorter than the CET. So you will see the hypoechoic musculo-tendinous junction within 10-15mm of the insertion.

Once you identify the CFT origin:

  1. Is it fibrillar
  2. Does it have a flat/slightly convex contour (if it is concave,it is torn)
  3. Is it hyperaemic?
  4. Is there fluid or calcification associated with the tendon?
  5. Is there bony irregularity?

Common Flexor Tendon origin ultrasound scan plane.

Ultrasound of Normal Common Flexor Tendon.

Ulna nerve

Ulna nerve anatomy

  • The ulna nerve runs between the bicep/tricep muscle bellies, where it exits via the arcade of Struthers.
  • At the elbow it  enters the cubital tunnel (ulna groove).
  • This is roofed by Osbornes ligament (fascia/band). The anatomic descriptions vary between a ligament between Humerus and Ulna, versus a fascia between the heads of the Flexor Carpi Ulnaris origins.
osbornes ligament anatomy ulna nerve
Ref: By S Bhimji MD - Range TL, Samra NS. Anatomy, Shoulder and Upper Limb, Osborne Band. [Updated 2020 Aug 15]. In: StatPearls [Internet]. 
  • The ulna nerve then descends the medial forearm to enter the antero-medial hand via Guyon's canal at the wrist.

To scan the ulna nerve:

  • Patient seated

Method 1

  • Elbow extended
  • Arm gently externally rotated

Method 2

    • Patient places their hand on their leg, fingers medially.
    • Elbow flexed and tilted towards you. 
    • This can give good stable access to posterior structures too.

To identify the Ulna nerve in the ulna groove:

  1. Palpate the medial humeral epicondyle and the olecranon tip.
  2. Place your probe bridging across these 2 landmarks. You will be in a transverse plane over the ulna groove.
  3. A normally positioned ulna nerve will be against the posterior aspect of the humeral epicondyle.
  4. Slide the probe proximally and distally to track the ulna nerve in a transverse plane. The ulna nerve can be tracked distally into the wrist and proximally between the bicep and tricep bellies into the axilla.
  5. Use colour doppler and rotate into LS if any pathology is suspected.

Dynamic assessment: Assess the ulna nerve for dislocation in the transverse plane of the ulna groove. The patient must slowly flex their elbow while you observe the nerve remaining in the groove.

TIP: The patient will need to flex their elbow entirely. So their hand approaches the ipsilateral shoulder.

Normal appearance:

  1. TRANSVERSE: Ovoid. Echogenic with multiple small hypoechoic spaces 9these represent the bundles of nerve fascicles)
  2. LONGITUDINAL: Hyperechoic and hypoechoic fibrillar pattern. Less fibrillar than a tendon.

TIP: The nerve can appear bifid in the region of the ulna groove due to the large neural fascicles.

Once you identify the ulna nerve:

  1. Is it uniform in thickness? Look for thickening or masses as it dives under Osbornes ligament between the flexor carpi ulnaris heads
  2. Is the echogenic rim (epineurium) thickened?
  3. Any surrounding hyperaemia?
  4. Does it remain in the ulna groove during full elbow flexion? It is normal for the nerve to slide superficially along the epicondyle but it should not leave the groove.  When it dislocates, it will come to rest on the common flexor tendon.
  5. Any bony irregularity or underlying joint effusion
  6. Any accessory muscle occupying the cubital tunnel (ie anconeus epitrochlearis muscle )

TIP: Up to 16% of people have a subluxing ulna nerve (REF pubmed) .

Scan Plane for Transverse Ulnar nerve.

(bridge the olecranon and the medial epicondyle)

Ultrasound of Normal Ulnar Nerve in the ulna groove.

Medial (Ulna) Collateral Ligament

To scan the Ulna Collateral Ligament:

  • Patient seated
  • Elbow approximately 45degrees flexed.
  • Arm gently externally rotated.
    •  

It is difficult to clearly identify all aspects of the medial (ulnar)collateral ligament:

  1. Begin with the CFT origin longitudinal view.
  2. Keep the marker end of the probe fixed on the medial epicondyle.
  3. Rotate the non-marker (heel) of the transducer posteriorly until the 'sublime tubercle' of the ulna rises. This represents the anterior bundle of the MCL.
  4. Continue to rotate until almost a transverse plane. The posterior bundle will form the floor of the ulna groove.

TIP: This requires slow movements keeping the medial humeral epicondyle on the screen at all times.

Normal appearance:

  • Hypoechoic bands with subtle fibrillar echotexture.
  • Tight, linear parallel margins.

Once you identify the MCL:

  • Is it uniform in thickness?
  • Is it hyperaemic on power doppler?
  • Is there associated fluid.

Ulna collateral ligament.

Ultrasound of Normal ulna collateral ligament.

For detailed protocol on scanning the lateral elbow

Posterior Elbow

  • Triceps tendon.
  • Olecranon fossa
  • Olecranon bursa 

Triceps insertion

To scan the triceps insertion:

  • Patient seated
  • The elbow needs to be flexed to about 60degrees.

Method 1

  • Patient sitting on a chair opposite you with their arm resting on the bed.
  • Elbow flexed

Method 2

  • Patient seated on a chair or the side of the bed.
  • Patient places their hand on their leg, fingers medially.
  • Elbow flexed and tilted towards you. 

To identify the triceps tendon:

  1. Palpate the olecranon tip.
  2. Place the probe longitudinally along the posterior distal humerus. Non-marker end on top of the olecranon, marker end towards the shoulder.
  3. Fan medially and laterally to assess all three heads.
  4. If intra-muscular pathology is suspected, follow each of the muscle bellies proximally.

TIP: You may need to rock the transducer to fully visualise the insertion around the flexed elbow tip.

Normal appearance:

LONGITUDINAL:

  • A short echogenic fibrillar tendon.
  • Slightly convex contour.

TRANSVERSE:

  • Appreciate the width of the tendon and the musculotendinous junction.
  1.  

Once you identify the triceps tendon:

  1. Is it intact?
  2. Is there calcification in the tendon?
  3. Is it hyperaemic?
  4. Is there any fluid deep to the tendon against the olecranon (the sub-tendinous or deep olecranon bursa).

TIP: Tension exostoses (spurs) off the olecranon tip are very common and rarely symptomatic.

Longitudinal triceps insertion.

Ultrasound of Normal longitudinal triceps insertion.

Olecranon bursa

To scan the common extensor tendon origin:

  • Patient

TIP: XXXXXX 

To identify the XXX:

  1. Palpate
  2. Slide

TIP: XXXXXX 

Normal appearance:

  1. TRANSVERSE: XXXX
  2. LONGITUDINAL: XXXX

Once you identify the XXXXX:

  1. Is it ...
  2. XXXX
  3. XXX

Ultrasound scan plane to assess the olecranon bursa.

Have the elbow almost fully extended.

Use light probe pressure and plenty of gel.

Ultrasound of the olecranon bursa region at the olecranon tip.

The bursa is not visualised when normal.

Olecranon Fossa

To scan the common extensor tendon origin:

  • Patient

TIP: XXXXXX 

To identify the XXX:

  1. Palpate
  2. Slide

TIP: XXXXXX 

Normal appearance:

  1. TRANSVERSE: XXXX
  2. LONGITUDINAL: XXXX

Once you identify the XXXXX:

  1. Is it ...
  2. XXXX
  3. XXX

Olecranon fossa Transverse scan plane.

Sweep through looking for fluid and loose calcific bodies.

Ultrasound of Transverse Olecranon Fossa.

Olecranon fossa longitudinal scan plane.

Sweep through looking for fluid and loose calcific bodies.

Ultrasound of the Olecranon Fossa in longitudinal.

For detailed protocol on scanning the posterior elbow

SCAN PROTOCOL

Role of Ultrasound

Ultrasound is essentially used for the external structures of the elbow. Ultrasound is a valuable diagnostic tool in assessing the following indications;

  • Muscular, tendinous and ligamentous damage (chronic and acute)
  • Bursitis
  • Joint effusion
  • Vascular pathology
  • Haematomas
  • Masses such as ganglia or lipomas
  • Classification of a mass e.g. solid, cystic, mixed
  • Post surgical complications e.g. abscess, oedema
  • Guidance of injection, aspiration or biopsy
  • Relationship of normal anatomy and pathology to each other
  • Some bony pathology

Limitations

  • Dressings
  • Inability to extend the elbow (at least 50%).

Patient Preparation

  • No preparation required.

Equipment setup

Use of a high resolution probe (7-15MHZ) is essential when assessing the elbow. Careful scanning technique to avoid anisotropy (and possible misdiagnosis). Beam steering or compounding can help to overcome anisotropy in linear structures such as tendons. Good colour / power / Doppler capabilities when assessing vessels or vascularity of a structure. Be prepared to change frequency output of probe (or probes) to adequately assess both superficial and deeper structures.

Common Pathology

  • Elbow joint effusion
  • Bursal effusion
  • Common extensor tendinopathy
  • Common flexor tendinopathy
  • Biceps brachii distal insertion tear and tendinopathy.
  • Ulnar nerve neuritis or dislocation
  • Radial nerve and PIN entrapment.
  • Superficial thrombophlebitis.

SCANNING TECHNIQUE

  • Take a good history.
  • As with any scan, be systematic. Treat the elbow as a cylinder. Begin laterally then scan the front, medial and posterior aspects.

PATIENT POSITION

Patient seated to provide easy access and movement of the elbow.

This can be:

  1. On a high swivel chair
  2. Seated on the side of the bed.
  3. Seated on a chair opposite the ultrasound bed, facing you with their arm resting on the bed.

LATERAL ELBOW 

  • For example images of pathology, click here to go to the elbow pathology page.

Common Extensor Tendon (CET) – ‘Tennis Elbow’:

  • Flex the elbow.
  • Put the toe of the probe on the lateral humeral epicondyle with the heel towards to wrist.
  • The CET will be a fibrillar echogenic flat topped insertion.

Look for:

  • Convexity indicating swelling (should be flat)
  • Loss of fibrillar architecture
  • Calcification
  • Hyperaemia

Radial Nerve

  • With the arm supinated.
  • Place the probe transversely, centered on the lateral aspect of the anterior elbow crease.
  • The radial nerve is directly beneath.
  • Follow it proximally around the back of the upper arm.
  • Then distally into the forearm where it divides into superficial and deep branches.

Look for:

  • Ganglia
  • Entrapment of the deep branch through the supinator.

Radial Collateral Ligament (RCL)

Is difficult to see (As with the Ulna collateral ligament).

  • Is a fan-like band.
  • With the elbow flexed.
  • The RCL is seen as an extension from the annular ligament around the radial head up to the humerus deep to the CET.

Look for:

  • Absence of the fibrillar architecture

ANTERIOR ELBOW

  • For example images of pathology, click here to goto the elbow pathology page.
  • Have the arm supinated and gently flexed.

Joint

  • Scan in sagittal across the antecubital fossa to assess for a joint effusion.

Biceps Brachii Tendon insertion

  • Begin in transverse and follow distally
  • Rotate into longitudinal and follow to the insertion
  • You will need pressure on the heel and to angle from the ulna aspect as the tendon dives to insert onto the radial tuberosity.

Look for:

  • Continuous integrity of the tendon from the musculo-tendinous junction to the insertion.

MEDIAL ELBOW 

For example images of pathology, click here to goto the elbow pathology page. 

Common Flexor Tendon (CFT)-‘Golfers Elbow’:

  • Flex the elbow.
  • Put the toe of the probe on the medial humeral epicondyle with the heel towards to wrist.
  • The CFT will be a fibrillar echogenic flat topped insertion.

Look for:

  • Convexity
  • Loss of fibrillar architecture
  • Calcification
  • Hyperaemia

Ulna Collateral Ligament (UCL) Is difficult to see (As with the radial collateral ligament).

  • Is a fan-like band. Usually the posterior aspect is affected.
  • With the elbow flexed.
  • The UCL is seen posterior and beneath the common flexor tendon.

Look for:

  • Absence of the fibrillar architecture

Ulna Nerve

  • With the elbow flexed.
  • Place the probe transversely, across the Olecranon and medial humeral epicondyle.
  • The ulna nerve is directly beneath in the ulna groove.
  • Follow it proximally around the back of the upper arm.
  • Then distally down to the wrist.

Look for:

  • Ganglia
  • Subluxation out of the groove during extension. 

POSTERIOR ELBOW

For example images of pathology, click here to goto the elbow pathology page.

  •  Triceps Insertion:
    • Place the heel of the probe on the tip of the Olecranon tip.
    • Assess in longitudinal and transverse.
    • Check the integrity of the tendon.
  •  Olecranon Fossa:
    • In longitudinal the dip in the posterior humerus is deep to the triceps.
    • In transverse the lateral borders of the fossa are visible.
    • Check for loose calcific bodies or fluid.
  •  Olecranon Bursa:
    • If particularly rounded and swollen, this can be difficult maintain contact to scan.
    • You may need a standoff pad or pile of thick gel over the slightly flexed Olecranon tip.
    • The swollen Olecranon bursa will be seen as a complex fluid collection over the Olecranon tip.
    • Usually has increased vascularity.

Basic Hardcopy Imaging

An elbow series should include the following minimum images.

  • Common extensor tendon
  • Radial nerve
  • Biceps brachii tendon
  • Median nerve
  • Anterior joint
  • Common Flexor tendon
  • Ulna collateral ligament
  • Ulna nerve
  • Triceps insertion
  • Olecranon fossa
  • Olecranon bursa
  • Document the normal anatomy and any pathology found, including measurements and vascularity if indicated.