Wrist SonographyCaitlin Gardiner

PreparationHave patient sitting on a chair across with

exposing their anterior wrist and resting their hand on the table with an absorbent sheet beneath

Select a high-frequency linear probe with a hockey stick probe if available

Ideally a thick coupling gel is used due to the hand contours

Purpose of UltrasoundChronic and Acute muscular, ligament and

tendon damageJoint effusionBursitisHaematomaGanglions/ other solid or cystic lesionsBony surfaceDynamic assessment of tendons and

relationships

Basic Bony Anatomy

Volvar Aspect of WristProximal Carpal Tunnel

Volvar Aspect of WristDistal Carpal Tunnel

Assessing Flexor TendonsStart transverse, scan to distal insertion, turn long when

assessing dynamic motion. Tear due to direct or non-direct traumaTear location need to be assess as well as the retraction of the

tendon endsAssess for typical fibrillar echotextureProximal end of a tear will show retracted tendon (swollen,

irregular and hypoechoic) which will not move on dynamic evaluation

Most commonly tears occur of the profundus tendon just proximal to its insertion

In entrapmentHypoechoic halo surrounding the tendon sheath will be more

distinct

Assessing the RetinaculaPowerful traction can cause tearsDislocation of the tendon can be found medially,

close to the extensor digitorum minimi or medial to the ulnar head

In entrapment conditionsVolvar bulging secondary to increases in intracanal

pressureMeasure, at the distal end of the carpel tunnel, the

distance between an arbitrary line from a) the hook of the hamate to the tubercle of the trapezium to b) the retinaculum and ensure the distance is not more than 4mm

Nerves of the Volvar AspectMedian Nerve

Enlarged in Carpel Tunnel SyndromeCan be easily tracked up the forearmImage in transverse and measure 2D volume at

widest pointImage in longitudinalIn Carpal Tunnel syndrome/entrapment,

Swollen at proximal portion (>10-12mm²) Decrease in overall echogenicity and normal

fascicular pattern Increase in vascularity in severe cases

Nerves of the Volvar AspectRadial Nerve

Clinically significant if inflamed as it crosses the first extensor compartment to reach the dorsal aspect of the wrist

Ulnar NerveProximal: Lies within Guyon’s canal between

the ulnar artery and the pisiformDistal: Divides into a superficial and deep

motor branch. The deep branch can be damaged by hook of the mate by compression

Nerve TumoursMostly affect median nerve and ulna nerveCompression can cause tinglingNeurinomas

Embedded inside the nerve and never fascicles are seen transverse within them

Easily surgically removedNeurofibromas

Arise at the periphery of the nerve and grow eccentrically

Transverse Dorsal AspectFirst position probe in transverse on distal

forearm so the radius and ultra are obtained. Move distally across the radio-carpal joint

(where two bones become three; the scaphoid, triquetral and lunate).

Note any ganglion as a poorly reflective fluid collection.

Transverse Dorsal AspectNote six compartments

Assessing Extensor TendonsTears often occur as a result of rheumatoid

tendosynovitis, causing friction between tendons and bon protuberances (Ulnar head and Lister’s tubercle)

Most commonly affected are the extensor digiti minimi and the extensor pollicis longus

Masses of the WristDescribe

Location: subcutaneous, subfascial plane or adherent to bone plane (measure distance to the skin for biopsy/surgery)

Borders: Regular, irregular or dendriticVascularityRelationship to surrounding structuresDynamic Behaviour (moves with tendons, compression etc)

Ganglia appear as anechoic structures with internal septa and has a fibrous wall and lacks a true synovial lining. They most commonly occur in the dorsal aspect of the wrist. Typically painless, firm masses

Other LesionsSubcutaneous and muscle haematoma appear

as fluid collectionsAbscess (following penetrating injury)

appears as a poorly defined heterogeneous mass with surrounding hyperaemia

Post-traumatic Intra-articular effusion can be visualised as a collection filling the joint space and the articular synovial recesses

Radiolucent foreign bodies can be detect on US (though x-ray shows radio-opaque bodies)

ReferencesBeggs I, Bianchi S, Bueno A et al.

Musculoskeletal Technical Guidelines: Wrist. European Society of Musculoskeletal Radiology.

Bianchi S and Matinoli C, 2007. Ultrasound of the Musculoskeletal System. Springer, Geneva.

McNally E, 2005. Practical Musculoskeletal Ultrasound. Elsevier Churchill Livingstone, Philadelphia.