ULTRASOUND OF THE HAND & FINGERS - Normal

For images of pathology, and detailed descriptions.

PALMAR ASPECT (Flexors)

Finger Flexors

There are 2 flexor tendons of the fingers:

• Flexor digitorum superficialis (inserting onto the distal phalanx)
• Flexor digitorum profundus Inserting as 2 separate slips onto the base of the middle phalanx.

Scan plane for the Flexor digitorum tendons. The Profundus and superficialis.	Normal Flexor digitorum Profundus (FDP) and superficialis tendons (FDS) at the level of the metacarpal neck.

Scan plane for the flexor digitorum tendons in transverse prior to the separation of superficialis from profundus.	The Flexor digitorum superficialis tendon slips (green) can be seen peeling off the Profundus portion (blue).

Scan plane for the flexor digitorum tendon at the A4 pulley, distal to the superficialis insertions.	Flexor digitorum profundus tendon in transverse. The neurovascular bundles are circled in red.

Scan plane for the flexor digitorum profundus insertion.	The Flexor digitorum profundus insertion onto the distal phalanx.

Pulleys

The flexor tendons are secured in place by a series of pulleys which are fibrous bands wrapping over the tendons and attaching to the bone.

• Annular pulleys: which wrap transversely over the tendons. Numbered A1 - A4 (see below).
• Cruciate pulleys: which are paired and cross diagonally over the tendons. Numbered C1 - C3. (see below).

The annular pulleys are readily visible with high resolution, high quality equipment. The cruciate pulleys are poorly seen.

Scan plane A2 pulley	A2 pulley at the proximal phalanx.

Scan plane for the A2 pulley in transverse.	Transverse view of the A2 pulley (green) firmly overlying the flexor digitorum tendon at the mid proximal phalanx.

Anatomy specimen showing the annular pulleys with the finger extended. Courtesy of Dr Andreas Schweizer. www.turntillburn.ch	Anatomy specimen showing the annular pulleys with the finger flexed. Courtesy of Dr Andreas Schweizer. www.turntillburn.ch

Palmar fascia

Scan plane when assessing for the palmar fascia (eg for Dupuytren's contracture)	Normal palmar fascia (green)

DORSAL ASPECT

Extensor digitorum tendons 

Unlike the flexors, there is only an extensor digitorum

Scan plane for the extensor digitorum insertion. Even with high frequency transducer, the very thin tendon is difficult to visualise without using a stand-off pad or thick gel.	The extensor digitorum tendon insertion to the distal phalanx. The tendon is extremely thin and lies intimately against the bone.

Nail-bed

Sac plane for the extensor digitorum insertion. Note the thick gel.	The nail bed is best viewed through a thick gel standoff.

Ulnar collateral ligament of the thumb (UCL)

• The ulnar collateral ligament of the 1st metacarpo-phalangeal joint laterally.
• Rupture is a skiier's or gamekeeper's thumb. If the torn ligament folds under the adductor pollicis it is referred to as a 'Stenner lesion'.

The ulnar collateral ligament on the 1st metacarpo-phalangeal joint.	Rupture is called a skiier's or gamekeeper's thumb. If the torn ligament folds under the adductor pollicis it is referred to as a 'Stenner lesion'.

ULTRASOUND OF THE HAND PROTOCOL

ROLE OF ULTRASOUND

To assess for:

• muscular, tendinous and ligamentous damage (chronic and acute).
• Foreign bodies.
• Joint effusions.
• 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.

EQUIPMENT SELECTION AND TECHNIQUE

Use of a high resolution probe (7-15MHZ)with a small footprint is essential when assessing superficial structures. 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.

SCANNING TECHNIQUE

Either:

1. Sit the patient on the side of the bed with a pillow on their lap to support their hand
2. Sit the patient on a chair on the opposite side of the bed with their hand resting on the bed.

Joint Effusions

For example images, click here to goto the hand & finger pathology page.

• Size
• Simple/complex
• Any synovial thickening
• Any vascularity on power doppler - Normal is little or no discernable flow. Hyperaemia = acute.

May need to compare with the other side.

Tendon abnormalities

For example images, click here to go to the hand & finger pathology page.

Look for hyperaemia, tendon sheath fluid (simple/complex) and tendon integrity/homogeneity

• Check for tendon thickening (compare with other side)
• Fluid in the tendon sheath
• Integrity of the tendon- any tear?
• does the tendon slide freely when mobilised?

Dupuytren's contracture

What is it?

• Fibrosis of the palmer fascia forcing the flexion of the 4th/5th fingers.
• Gradual onset
• M>F
• Often inherited.
• Generally affects 4th and 5th fingers.

Scan in longitudinal from the base of the proximal phalanx down into the palm looking superficial to the flexor tendon

It will appear as a hypoechoic focal fusiform thickening of the palmar fascia at the metacarpal head level. Not to be confused with trigger finger (see below).

Trigger finger

For example images, click here to go to the hand & finger pathology page.

What is it?

Tenosynovitis of a flexor digitorum tendon causing forced flexion of a finger.

Initially in transverse, identify the flexor digitorum tendons at the metacarpal head level. Follow the common tendon proximally to the carpal tunnel. Then follow distally to the insertions: The Flexor digitorum superficialis divides, with two slips inserting onto the side of the base of the middle phalanx. Flexor digitorum profundus inserts onto the distal phalanx

Finger Pulleys

For example images, click here to go to the hand & finger pathology page.

What are they? Bands of fibrous tissue holding the flexor tendon to the finger similar to runners on a fishing rod.

They are named according to their type-Annular (around) or Cruciform (cross), and numbered from proximal to distal. EG: A1 to A5 and C1 to C4.

Scan longitudinally over the anterior surface of the finger. The pulleys may be seen as thin hypoechoic zones intimately overlying the flexor tendon sheath.

If ruptured, the tendon will no longer follow the bone and will instead "bowstring".

Game keepers thumb/ skiiers thumb

For example images, click here to goto the hand & finger pathology page.

What is it?

Rupture of the ulnar collateral ligament of the thumb due to a sudden valgus force.
May occur after repeated stretching of the ligament.

The ligament usually tears at it's distal end from the base of the proximal phalanx. If there is marked angulation of the phalanx, the flailing ligament may impinge under the adductor pollicis creating a ' Stenner lesion '.

Click here for detailed information.

Foreign bodies

For example images, click here to goto the hand & finger pathology page.

Ensure you approach the proposed site of the foreign body from different angles. Some materials will be poorly reflective and almost invisible unless the beam is perpendicular to them. There will usually be a surrounding hypoechoic halo representing an inflammatory reaction

Identify:

• The plane of tissue it is in.
• How close it is to the entry wound and to any blood vessels.
• It may be helpful to mark the location and orientation of the foreign body on the skin to guide removal.

Masses

95% of finger tumours are benign(ref: emedicine)

• abscess
• granuloma
• Ganglia
• Neuroma
• Fibroma
• Glomus tumour (nail bed tumour)

For non-specific palpable or visible masses see our superficial lumps page.

Joint Abnormalities

For example images, click here to goto the hand & finger pathology page.

• Gout: Abnormal uric acid metabolism resulting in joint inflammation. May see tophaceous gout as a complex echogenic mass (tophus) in the soft
• Osteoarthritis: Bony irreg at the bone ends with joint effusion. When acute the joint will be hyperaemic
• Rheumatoid arthritis: Thickened synovium with a complex 'thick' joint effusion, pannus & associated bony irregularity

Click here to read a great article on hand ultrasound.

BASIC HARD COPY IMAGING

Hard copy imaging should reflect the anatomy investigated.

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