7: Hand and Wrist Flashcards
flexion and extension of thumb
flexion: can flex at both the IPJ and MCPJ/ when both joints are flexed, thumb bends across the palm
extension: return flexed thumb to anatomical position
radial abduction
continuation of extension beyond the anatomical position in the same plane as the palm (coronal plane)
opposition
rotatory movement of the thumb over the palm - it enables the thumb to touch the tips of the fingers
palmar adduction/abduction
circumduction
what is the carpal tunnel
narrow passageway on the anterior (volar or palmar) surface of the wrist that serves as an entrance to the palm for numerous tendons and median nerve
what are the borders of the carpal tunnel
deep border: comprised of the carpal bones which form a concavity
superficial border: flexor retinaculum aka transverse carpal ligament
what are the attachments of the flexor retinaculum
radial (lateral): scaphoid, trapezium
ulnar (medial) : hook of hamate, pisiform
what structures pass through the carpal tunnel
- flexor pollicis longus tendon
- flexor digitorum superficialis tendons x4
- flexor digitorum profundus tendons x4
- median nerve
where is the palmar cutaneous branch of the median nerve given off
proximal to the carpal tunnel
- clinically important in carpal tunnel syndrome as when the median nerve becomes compressed, sensation to the palm is unaffected
what is guyon’s canal
aka ulnar canal
semi-rigid longitudinal canal in the wrist that allows passage of the ulnar nerve and artery into the hand
where is guyon’s canal found
superficial to the flexor retinaculum
- can be palpated just radial (lateral) to the pisiform bone, passing between pisiform and hook of hamate
- roof: formed by palmar carpal ligament
why is guyon’s canal clinically important
site of ulnar nerve compression
what is the anatomical snuffbox (aka radial fossa)
triangular depression on the radial aspect of the dorsum of the hand, at level of carpal bones
- best seen when thumb is radially abducted
what are the borders of the snuff box
- radial: tendons of abductor pollicis longus (most lateral) and extensor pollicis brevis
- ulnar: tendon of extensor pollicis longus
- proximal: styloid process of radius
- floor: scaophoid and trapezium
- roof: skin
what are the contents of the anatomical snuff box
- radial artery
- superficial branch of radial nerve
- cephalic vein
which arteries supply the hand
radial and ulnar artery supply hand via deep and superficial palmar arches
where can the ulnar artery be palpated
- may be palpated as it crosses anterior to flexor retinaculum + ulnar nerve in guyon’s canal
- here the artery lies radial to pisiform bone and ulnar nerve
in the hand, what does the ulnar artery divide into
superficial and deep branches
- both of which anastomose w corresponding branches of the radial artery to form superficial and deep palmar arches
what does the superificial palmar arch give off
common palmar digital arteries which supply the fingers
what does the ulnar artery contribute mainly to
the superificial palmar arch and therefore to the blood supply of the fingers
how does the radial artery enter the hand
between the tendons of brachioradialis and flexor carpi radialis
what does the radial artery give off
superficial branch that anastomoses w the superficial palmar arch then passes dorsally to cross the floor of the anatomical snuffbox on the dorsum of the hand before re-entering palm between two heads of adductor pollicis
what does the radial artery anastomose with
deep branch of ulnar artery to form deep palmar arch
what does the radial artery mainly contribute to
the deep palmar arch and therefore to the blood supply of the thumb and the radial side of the index finger
what are the three branches of the brachial plexus that supply motor and sensory function to the hand
median
radial
ulnar
where does the radial nerve arise from
posterior divisions of the brachial plexus
- supplies posterior compartment of forearm
where do the median and ulnar nerve arise from
anterior divisions of the brachial plexus
- supply the anterior compartment of the forearm and muscles of the hand
what does the ulnar nerve supply
all intrinsic muscles of the hand except:
- Lumbrical
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis (superficial head)
what else is the sensory supply to the hand based upon
embryological development
- fingernails initially develop on the volar aspect of the hand and are dragged over to the dorsal aspect
- as they migrate, they take their nerve supply with them
- the nailbed and dorsal skin overlying the distal phalanx of each finger is innervated by the nerve that innervates the palmar aspect
where is the nerve supply to the palm of the hand derived from
palmar cutaneous branch of the median nerve
- arises proximal to the carpal tunnel
palmar cutaneous branch of the ulnar nerve
- arises proximal to Guyon’s canal
what do the palmar digital branches of the median nerve supply
thumb
index finger
middle finger
radial border of ring finger
what do the palmar digital branches of the ulnar nerve supply
ulnar border of the ring/little finger
- also innervate the dorsum of these digits over the distal phalanx and nail bed
what does the dorsal cutaneous branch of the ulnar nerve supply
skin over the dorsal aspect of the ulnar border of the hand and skin over the dorsum of the ulnar 1 1/2 digits, as far distally as DIPJ
testing sensation in the peripheral nerve territories
some overlap between cutaneous territories of the peripheral nerves so always test sensation in the regions known to have a consistent supply:
- radial nerve: dorsum of the first webspace
- median nerve: palmar surface of the tip of the index finger
- ulnar nerve: ulnar border of the hand
scaphoid fractures
70-80% of the fractures of the carpal bones and 10% of all hand fractures
- may occur at any age but most common amongst adolescents and young adults following fall onto outstretched hand
- hyperextension and impation of the scaphoid against the rim of the radius or in diret axial compression of the scaphoid
what do pt with scaphoid fracture usually complain of
pain in the anatomical snuffbox
- exacerbated by moving the wrist
- passive range of motion is reduced but not dramatcally
- swelling around the radial and posterior aspects of the wrist is common
what part of the scaphoid do most fractures affect
waist of the scaphoid (70-80%)
- also ocur in proximal pole (20%)
- distal pole (10%) - sometimes alled the scaphoid tubercle
X-raying a scaphoid fracture
- plain x-rays immediately after injury may not reveal the fracture so delayed diagnosis is common
- if initial fracture does not show fracture, obtain follow up after 10-14 days as fracture lines may become more visible after some bone resoprtion
- but in meantime, treat pt as if they have a fracture
- if still not clear then use CT or MRI
why is there a high risk of avascular necrosis in scaphoid fractures
- blood supply to scaphoid is mainly retrograde from distal to proximal pole
- since blood supply to the proximal pole is tenuous, fractures through the wasit of the scaphoid can result in avasacular necrosis
what is a colles’ fracture
an extra-articular fracture of the distal radial metaphysis, with dorsal angulation and impaction
- associated ulnar styloid fracture is present in up to 50% of cases
what is there a high risk of w displaced fratures through wasit of scaphoid
- non-union
- malunion
- avascular necrosis
- late complications of carpal instability
- secondary OA (more common if there has been one of the above)
what is the most common type of distal radial fracture
Colles’ fracture
who are Colles’ fractures common in
pt w osteoporosis and they have a reduced bone density
- post-menopausal women
- younger ppl who have this usually involved in high impact trauma e.g. skiing
mechanism of injury of Colles’ fracture
fall onto outstretched hand (FOOSH) w pronated forearm and wrist in dorsiflexion
- energy transmitted from the carpus to the distal radius in a dorsal direction and along the long axis of the radius = usually dorsally angulated and impacted
presentation of Colles’ fracture
painful, deformed, swollen wrist
Colles’ fracture X-Ray
- fracture line, dorsal angulation and impation are usually clearly visible on plain x-ray, especially at lateral view
treatment of Colles’ frature
reduction and immobilisation in cast
complications of Colles’ fracture
- malunion = dinner fork deformity
- median nerve palsy and post traumatic carpal tunnel syndrome
- seondary OA (more common w intra-articular fractures)
- tear of extensor pollicis longus tendon through attrition of the tendon over a sharp fragment of bone
what is a smith fracture
- fractures of the distal radius w volar (palmar) angulation of the distal fracture fragments
- 85% are extra-articular so can be thought of as reverse Colles’ fracture
- less than 3% of all radial and ulnar fractures
typical mechanism and age group of smith fracture
- young males most common
- elderly females
- fall onto dorsum of a flexed wrist or direct blow to bak of the wrist
deformity of smith fracture
malunion w residual volar displaement of distal radius = cosmetic defomirt referred to as ‘garden spade’ deformity
- narrows and distorts carpal tunnel –> syndrome
mechanism of RA
autoimmune disease where autoantibodies known as rheumatic factor attack synovial membrane
- inflamed synovial cells proliferate to form pannus –> penetrates through the cartilage and adjaent bone –> joint erosion and deformity
- symmetrical polyarthritis = affecs multiple joints –> can make mild swelling in hand difficult to diagnose as there is no normal hand
where does RA particularly affect
MCPJ
PIP
cervical spine
can involve large joints
what do pt w RA present w
- pain and swelling of PIPJs and MCPJs of fingers
- erythema overlying joints
- stiffness, worse in morning or after periods of inativity
- carpal tunnel syndrome due to synoival swelling
- fatigue and flu-like symptoms due to systemic nature of siease
- rheumatic nodules in fingers and over elbow are usually late feature
x-ray features of RA
- loss of joint space
- periarticular osteopenia
- juxta-articular bony erosions
- subluxation and gross deformity
common deformities seen in pt w advanced RA
- swan neck deformity
- boutonniere deformity
swan neck deformity formation
PIPJ hyperextends and MCPJ/DIPJ flexed
- tissues on volar aspect of PIPJ become lax due to adjacent synovitis = primary abnormality
- imbalance between muscle forces acting on PIPJ (extension > flexion) so joint w lax tissues become hyperextended
- at DIPJ, either elongation of rupture of insertion of extensor digitorum into base of distal phalanx = mallet deformity
describe formation of Boutonniere deformity
MCPJ and DIPJ hyperextension and PIPJ flexion
- inflamm in PIPJ –> lengthening/rupture of the central slip of extensor at its insertion into base of middle phalanc on dorsal surface of finger
- lateral bands of extensor digitorum tendon slip down sides of finger so now on palmar surface at level of PIPJ
- instead of ating as extensors of PIPJ, they start to act as flexors + hyperextending DIPJ$
psoriatic arthropathy
- only minority of pt w psoriasis will develop arthritis
- commonly affects DIPJ
- when it develops, usually an asymmetrical oligoarthritis meaning it develops in one joint at a time, progressing in asymmetrical manner
- psoriatic arthritis involves small joints of hands and feet
how does a pt w psoriatic arthropathy present
fusiform swelling of digits (dactylitis)
- affected joints stiffen and if disease progresses –> widespread joint destruction called arthritis mutilans
onycholysis (separation of nail from nail bed)
pitting
what is the most commonly affected joint by OA in the hand
1st carpometacarpal joint (between trapzeium and first metacarpal)
- more common in women
what will pt w OA of 1st CMCJ complain of
- pain at base of thumb exacerbated by movement, relieved by rest
- stiffness increases following periods of rest e.g. in mornings
- mat be some swelling evident around the base of thumb
- in later stages, 1st metacarpal subluxes in ulnar direction = loss of normal contour and squaring of the hand
what are Heberden’s node and how do they develop
- classic sign of 3 affecring DIPJ of fingers
- typically develop in middle age and more common in women then men
- tend to run in familiies, suggesting genetic predisposition
- begin w either a chronic swelling of affected joints/ sudden onset of pain, swelling and loss of manual dexterity
- intially pt develops cystic swelling containing gelatinous hyaluronic acid on dorsolateral asepct of DIPJ
- initial inflamm and pain eventually subsides and pt left w an osteophyte
what are Bouchard’s nodes
same process as Heberden’s nodes developing but in the PIPJs
what is carpal tunnel syndrome
compression of the median nerve as it passes through the carpal tunnel from the forearm into the hand
- most common site of nerve entrapment in the body
what is carpal tunnel syndrome
compression of the median nerve as it passes through the carpal tunnel from the forearm into the hand
- most common site of nerve entrapment in the body
risk factors of carpal tunnel syndrome (5)
obesity
repetitive wrist work
pregnancy
RA
hypothyroidism
what can nerve compression result in
ischaemia
focal demyelination
decrease in axonal calibre
eventually axonal loss
what would a pt w carpal tunnel syndrome experience
- paraesthesia in distribution of median nerve: (thumb, index, middle, radial 1/2 of ring)
- symptoms often worse at night and can wake pt from sleep
- as conditions worsen, daily activites e.g. driving, combing hair can aggravate paraesthesia
why is sensation to the palm spared in carpal tunnel syndrome
palmar cutaneous branch of median nerve branches proximal to carpal tunnel and passes superficial to it into the palm (so not compressed)
what can long-standing carpal tunnel syndrome result in
muscle weakness and atrophy of thenar muscles (superficial head of flexor pollicis brevis, abductor pollicis brevis and opponens pollicis)
what actions will be normal in carpal tunnel syndrome and why
- flexion of thumb: flexor pollicis longus is innervated by anterior interosseus branch of the median nerve in forearm/deep head of flexor pollicis brevis by ulnar nerve
- adduction of thumb: adductor pollicis supplied by ulnar nerve
what nerve can be compressed in guyon’s canal
ulnar
- as it passes radial to pisiform bone over the volar surface of the flexor retinaculum
- aka ulnar tunnel syndrome, Guyon’s canal syndrome or handelebar palsy
what do pt w ulnar tunnel syndrome complain of
- paraesthesia in the ring and little fingers, progressing to weakness of intrinsic muscles of hand supplied by ulanr (notabily adductor pollicis and palmar/dorsal interossei)
- also lumbricals to ring and little fingers and deep head of flexor polliis brevis
what is dupuytren’s contracture
common condition in which there is localised thickening and contracture of the palmar aponeurosis –> flexion deformity of the adjacent fingers
how does dupuytren’s contracture develop
- initially = thickening or ‘nodule’ in their palm, which can be painful or painless
- later, myofibroblasts within nodule contract leading to the formation of tight bands called ‘cords’ in the palmar fascia
- overlying skin is tightly adherent to palmar aponeurosis and becomes involved –> progresses to involve the proximal fascia and skin of the fingers
- fingers become stuck in flexed position and cannot be passively straightened
most commonly affected digits in dupuytren’s contracture
ring and little finger but first websapce and thumb may also be involved
- 40-60yrs
- more common in males
- north eastern origin
- famil history with autosomal dominant inheritance
- remainder of cases = sporadic
what are conditions that inc risk of developing dupuytren’s contracture
- type I diabetes
- epilepsy, taking certain medications e.g. phenytoin, barbiturates
- liver disease and/or excess alcohol consumption
- smoking
- hypercholesterolaemia
- heart disease
- HIV
describe formation of Boutonniere deformity
MCPJ and DIPJ hyperextension and PIPJ flexion
- inflamm in PIPJ –> lengthening/rupture of the central slip of extensor at its insertion into base of middle phalanc on dorsal surface of finger
- lateral bands of extensor digitorum tendon slip down sides of finger so now on palmar surface at level of PIPJ
- instead of ating as extensors of PIPJ, they start to act as flexors + hyperextending DIPJ$
what measurements are relevant in imaging of a distal radius fracture
what is flexor tendon sheath infection and what is the most common cause
inflammation of the tendon sheath
- bacterial infection via S.aureus/epidermis
why is flexor tendon sheath infection a surgical emergency
raised pressure in the tendon sheath can impair blood flow –> necrosis of tendons and devitalisation of fingers
what are common mechanisms of flexor sheath infection
- penetrating trauma
- direct spread from felons, septic joints
- haematogenous
what are risk factors of flexor sheath infecrion
- diabetes
- IV drugs
- immunocompromised
what are Kanavel’s signs
4 cardinal features of flexor sheath infection:
- pain of passive extension of digit (earliest sign)
- tenderness on palpation
- fusiform swelling
- flexed finger
what is the immediate and operative management of flexor sheath infection
- immediate: hand elevation and broad spec abx then refer
- operative: w/in 24 hours surgical flexor sheath washout and samples sent to microbiology
what is Froment’s sign
used to test function of adductor pollicis muscle
- pinch paper between thumb and index finger against resistance and if the aPL is weak, thumb IP joint will flex
what is de Quervain’s tenosynovitis
inflammation of the EPB and AbPL tendon sheath causing radial styloid process pain and painful abduction of the thumb against resistance (+ve Finketlstein test)
