wrist sonography
DESCRIPTION
Wrist Sonography. Caitlin Gardiner. Preparation. Have 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 - PowerPoint PPT PresentationTRANSCRIPT
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.