Wrist normal

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

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.

Posterior (Dorsal) Wrist

The posterior wrist tendons are separated into 6 compartments.

  1. Compartment 1: Abductor Pollicus Longus (APL) and Extensor Pollicis Brevis (EPB).
  2. Compartment 2: Extensor Carpi Radialis Longus &Extensor Carpi Radialis Brevis.
  3. Compartment 3: Extensor POllicis Longis.
  4. Compartment 4: Extensor Digitorum
  5. Compartment 5: Extensor Digiti Minimi.
  6. Compartment 6: Extensor Carpi Ulnaris.

Other posterior wrist structures to assess.

  • Wrist joints (particularly the dorsal recess)
  • Scapho-lunate ligament.
  • Proximal intersection (compartment 1 over compartment 2)
  • Distal Intersection (compartment 3 over compartment 2)
Schematic of the dorsal wrist tendons
Schematic of the dorsal wrist tendons.

To assess the tendons:

  1. Scan each tendon in transverse from the musculo-tendonous junction to the mid hand.
  2. Rotate into longitudinal and mobilise each tendon to ensure it is intact and glides freely.

TIP: Rest the patient's wrist over a rolled towel gentle flexed to create tension on the tendons.

Normal appearances:

  1. The tendons should be echogenic and fibrillar.
  2. No fluid should be visible in the tendon sheaths.
  3. Become familiar with the retinaculae overlying the tendons.

TIP: The retinaculum overlying the extensor digitorum and extensor carpi ulnaris are thicker than the remaining retinaculae.

Most common findings:

  1. Fluid in tendon sheaths
  2. Joint effusions (simple or complex)
  3. Synovial thickening (tendon sheath or joint)
  4. Increased vascularity.
Schematic of the dorsal wrist tendons

The 6 dorsal wrist compartments:

Each is separated by a reflection of the overlying extensor retinaculum.

Compartment 1:  Abductor Pollicis Longus (APL) & Extensor Pollicis Brevis (EPB)

Compartment 1 scan plane:

Abductor Pollicis Longus and Extensor Pollicis Brevis (APL/EPB)

Transverse ultrasound of the APL/EPB tendons.

At the level of the retinaculum on the distal radius.

Compartment 2:  Extensor Carpi Radialis Longus (ECRL) & Extensor Carpi Radialis Brevis (ECRB)

Compartment 2 Scan plane:

Extensor Carpi Radialis, Longus and Brevis.

Transverse view ultrasound of the extensor carpi radialis longus and brevis tendons.

Compartment 3:  Extensor Pollicis Longus (EPL)

Compartment 3 scan plane:

Extensor Pollicis Longus tendon.

Ultrasound- The EPL tendon is tucked against Lister’s Tubercle. The Extensor digitorum longus common tendon is adjacent, in compartment 4.

Compartment 4:   Extensor Digitorum Communis tendons (ED)

Compartment 4 scan plane:

Extensor Digitorum tendons.

Ultrasound of the Extensor Digitorum Communis tendon at the level of the extensor retinaculum.

Compartment 4 scan plane:

Extensor Digitorum tendons.

Ultrasound of the common extensor digitorum tendons which  have divided into 4 proximal to the wrist crease.

Compartment 5:  Extensor Digiti Minimi (EPM)

Ultrasound scan plane of the extensor digiti minimi.

This is a small tendon. It lies ulnar to compartment 4 but varies in it’s proximity to the extensor digitorum communis tendon and the more ulnar, extensor carpi ulnaris tendon.

Ultrasound of Extensor Digiti Minimi tendon, immediately ulnar to the extensor digitorums.

Compartment 6:  Extensor Carpi Ulnaris (ECU)

Compartment 6 scan plane:

Extensor Carpi Ulnaris tendon.

Ultrasound of the Extensor Carpi Ulnaris tendon.

Scapho-lunate ligament: 

Scapho-lunate ligament scan plane.

Ultrasound – Scapho-lunate ligament is seen as a fibrillar tight band.

Visualising the SCL does not exclude carpal instability.

REF: AJR article

Proximal Intersection:  Compartment 1 musculo-tendinous junction crossing compartment 2.

Scan plane for ultrasound of wrist intersection syndrome.

The red circle shows the distal intersection (EPL crossing compartment 2)

The orange circle shows the proximal intersection. The musculotendinous junction of compartment 1 crossing compartment 2.

Proximal intersection normal ultrasound appearance.

Abductor pollicis longus musculo tendinous junction crossing the extensor carpi radialis tendons.

Another normal proximal intersection demonstrating variation in musculature. This example shows a commonly seen larger extensor Pollicis Brevis musculotendinous junction.

Normal distal intersection of the wrist
Ultrasound of the distal intersection in the wrist as EPL crosses the ECR tendons.

Proximal intersection normal ultrasound appearance.

Compartment 1 crossing compartment 2.

Distal Intersection:  Compartment 3 crossing compartment 2.

Transverse view of the distal intersection where extensor pollicis longus tendon (EPL) crosses the extensor carpi radialis tendons (ECRL and ECRB)

Normal distal intersection of the wrist
Ultrasound of the distal intersection in the wrist as EPL crosses the ECR tendons.

Dorsal wrist joints: 

  1. Radio-ulna
  2. Radio-carpal
  3. Mid carpal

The 3 joint planes of the wrist:

  1. Radio-ulna
  2. Radio-carpal
  3. Intercarpal

Radio-ulna joint (red arrow)

Slide distally to assess beyond the ulna for effusion or synovial changes (see the joint anatomy image)

Ultrasound of a normal posterior radio-carpal joint with highlighted anatomy.

The dorsal recess has a complex appearance. Commonly, tiny air bubbles will be visible as echogenic foci, as in this example.

Ultrasound scan plane of the radio carpal, dorsal recess of the wrist.

Anterior Wrist

Click here

For detailed scanning protocol

A basic schematic of the anterior wrist tendons and Carpal Tunnel. Click image to enlarge

A basic schematic of the anterior wrist tendons and Carpal Tunnel.

Click image to enlarge.

Carpal Tunnel

Carpal tunnel ultrasound, transverse scan plane.

Ultrasound Transverse carpal tunnel.

Flexor carpi radialis (FCR); Flexor Pollicis Longus (FPL); Median Nerve (MN); Flexor Digitorums.

Flexor Carpi Radialis (FCR)

  • Origin: Medial epicondyle of humerus.
  • Insertion: anterior surface of base of 2nd metacarpal. Lesser insertions base of third metacarpal, and trapezial tuberosity.
  • Action: Flexes and aBducts (radial deviates) the hand at the wrist.

Scan plane for the Flexor Carpi Radialis (FCR) tendon.

Ultrasound of the Flexor Carpi Radialis tendon curving over the scaphoid to insert onto the 1-2 metacarpal bases.

Flexor Carpi Ulnaris

  • Origin: Epicondyle of humerus & medial border of olecranon.
  • Insertion: Palmar surface of pisiform. Lesser insertions at hamate, and base of 5th metacarpal.
  • Action: Flexes and aDducts (ulna deviates) the hand at the wrist.

Scan plane for the Flexor carpi Ulnaris tendon.

Ultrasound of the Flexor Carpi Ulnaris tendon.

Palmaris Longus

  • Origin: Medial epicondyle of humerus.
  • Insertion: transverse carpal ligament and palmar aponeurosis.
  • Action: Flexes hand at the wrist.

Anatomical variability:

  • Absent in up to 25% of the population.
  • Has no tendon sheath or synovium.
  • Commonly harvested for tendon grafts.

Ultrasound scan plane of palmaris longus

The palmaris longus is seen immediately under the skin, superficial to the flexor tendons proximal to the wrist crease.

Palmaris longus ultrasound, transverse scan plane.

(same as the carpal tunnel)

Ultrasound of the Palmaris longus tendon in a transverse plane at the wrist crease.

Palmaris longus ultrasound, longitudinal scan plane.

(same as the carpal tunnel)

Ultrasound of the Palmaris longus tendon in a transverse plane at the wrist crease.

Triangular Fibro Cartilage Complex (TFCC)

  • Unlike the radius, the Ulna does not articulate directly with the carpal bones.
  • The TFCC is a heterogeneous area of tissue between the Ulna and the Triquetrum

Scan plane for ultrasound of the Triangular Fibro-cartilage Complex (TFCC)

The complex anatomical planes of the TFCC make it difficult to investigate well with ultrasound.

SCAN PROTOCOL

Role of Ultrasound

Ultrasound is a valuable diagnostic tool in assessing the following indications in the wrist:

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

Limitations

Recent surgery or injections may degrade image quality through the presence of air in the tissue.

Patient Preparation

None required.

Equipment setup

  • Use of a high resolution probe (10-15MHZ) is essential when assessing the superficial structures of the wrist.
  • Careful scanning technique to avoid anisotropy (and possible mis-diagnosis).
  • 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

  • Joint effusions
  • Teno-synovitis
  • Athroses
  • Tendon tears
  • Foreign bodies
  • Abscess/collections
  • Carpal tunnel (median nerve compression)

SCANNING TECHNIQUE

  • Begin your scan at the wrist crease.
  • Initially, survey each tendon in transverse from the musculo-tendinous junction to the distal insertion.
  • Then assess in longitudinal also.
  • The tendon sheaths approximately extend for a couple of cm either side of the wrist crease.
  • If necessary, you can compare with the contralateral side.

POSTERIOR WRIST

 

Schematic of the dorsal wrist tendons
Schematic of the dorsal wrist tendons.

Abductor pollicis longus(APL) and Extensor Pollicis Brevis (EPB)The posterior wrist is conveniently divided into 6 compartments:

  1. Extensor Carpi Radialis (ECR) longus and Brevis
  2. Extensor Pollicis Longus (EPL)
  3. Extensor Digitorum (ED)
  4. Extensor Digiti Minimi (EDM)
  5. Extensor Carpi Ulnaris (ECU)

These are all tethered by the extensor retinaculum which overlies ,and in some areas reflects around, the tendons.

Begin by scanning over the lateral wrist crease at the anatomical “snuff-box”. You should see the APL & EPB in compartment 1. To check, both tendons should be able to be followed up the thumb. If they go to the carpus you have slipped medially onto compartment 2. Work your way sequentially across the wrist assessing each tendon individually.

De Quervain’s tenosynovitis

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

  • Inflammation of the Abductor Pollicis Longus and Extensor pollicis Brevis tendons.
  • Overuse injury.
  • Patients present with focal, point tenderness laterally over the radial styloid.

Proximal intersection syndrome

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

Extensor Pollicis Brevis crossing over extensor Carpi Radialis longus & Brevis.

Distal intersection syndrome

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

Ext Pollicis Longus crossing over extensor Carpi Radialis longus & Brevis.

Scapho-lunate ligament

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

The wrist is essentially divided into 3 joint planes:

1. and 2. The radiocarpal and midcarpal Joints allow wrist flexion, extension and lateral deviation.

3. The distal radio-ulnar joint allows the forearm and hand to rotate. (Pronation / Supination).

These joints are supported by a series of extrinsic and intrinsic ligaments. The scapholunate ligament is the most important dorsal intrinsic stabiliser.

  • Injury occurs with a hyperextension of the wrist. Similar mechanism to a scaphoid fracture but results in a ligament tear instead.
  • If only a partial tear it is usually stable.
  • If complete, it results in Scapho-lunate instability. The scaphoid will rotate abnormally during wrist movement, which if left untreated can lead to significant chronic wrist degeneration.

NOTE:

Visualising the SCL does not exclude carpal instability. (REF: AJR article )

ANTERIOR WRIST

A basic schematic of the anterior wrist tendons and Carpal Tunnel. Click image to enlarge
A basic schematic of the anterior wrist tendons and Carpal Tunnel.
Click image to enlarge


For pathology example images, click here to goto the wrist pathology page.Carpal Tunnel Syndrome

This is the most common peripheral nerve entrapment. It occurs when the median nerve is compressed by the overlying flexor retinaculum.

IMPORTANT:

  • Ultrasound cannot exclude Carpal tunnel syndrome. The accepted standard for diagnosis is a nerve conduction study.
  • Our role is to identify possible causes for the patient’s symptoms.

Look for:

  • Tendon abnormalities
  • Ganglia
  • Fluid
  • Accessory muscles
  • Any asymmetry with the contra lateral side.

There have been several proposed methods of quatitative assessment for carpal tunnel. In our experience, these have not been reliable. They include:

  • Nerve cross sectional area of >10square mm proximal to the retinaculum.
  • Nerve flattening ratio of 3:1 (Yesildag et al – Clinical Radiology).

Guyons Canal Syndrome

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

Canal bordered by the pisiform & hamate and roofed by a reflection of the flexor retinaculum. The ulna nerve and artery pass through and may become entrapped or injured. Repetitive injury such as cycling or using heel of hand as hammer.

On Ultrasound: As with carpal tunnel look for ganglia, accessory muscles and asymmetry with the contra lateral side

Triangular FibroCartilage Complex (TFCC)

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

  • A section of cartilage and ligaments at the distal ulna.
  • Provides a continuous gliding surface along the forearm-carpal joint.

Affected by:

  • Natural degeneration with age.

Or injuries:

  • FOOSH
  • Forced rotation (stuck drill)
  • Racquet sports
  • Direct blow to medial wrist

Basic Hardcopy Imaging

A wrist series should include images specific to the area clinically indicated from a thorough history and physical examination.

  • Document the normal anatomy. Any pathology found in 2 planes, including measurements and any vascularity.