6: Elbow and Forearm Flashcards
superficial muscles of anterior compartment of forearm
flexor carpi ulnaris
palmaris longus
flexor carpi radialis
pronator teres
intermediate muscles of anterior compartment of forearm
flexor digitorum superficialis
deep muscles of anterior compartment of forearm
flexor pollicis longus
flexor digitorum profundus
pronator quadratus
actions associated w anterior forearm
proantion of forearm
flexion of wrist
flexion of fingers
innervation of anterior forearm
mostly median nerve
- except for flexor carpi ulnaris and medial 1/2 of flexor digitorum profundus which are ulnar
arterial supply of anterior forearm
ulnar and radial artery
origin of all superficial muscles anterior forearm
common tendon which arises from medial epicondyle of humerus
prosection of superficial anterior forearm
prosection of intermediate layer of anterior forearm
prosection of deep layer of anterior forearm
borders of cubital fossa
lateral: medial border of brachioradialis
medial: lateral border of pronator teres
superior: horizontal line between epicondyles of humerus
roof of cubital fossa
bicipital aponeurosis
subcutaneous fat and skin
fascia
- also contains median cubital vein which connects basilic and cephalic veins which can be easily accessed for venepuncture
floor of cubital fossa
proximally: brachialis
distally: supinator
how do conditions of the elbow present
- pain
- swelling
- restriction of movement
- deformity
- different conditions common at different ages
supracondylar fracture
- up to 75% of all elbow injuries
- most common pediatric elbow fracture >10 yrs (peak age 5-7)
- more common in boys
- most common mechanism: falling from moderate height onto outstretched hand w elbow hyperextended
- presents w pain, swelling, deformity, bruising
- history of trauma
- less common mechanism: 5% - falling onto flexed elbow
classification of supracondylar fractures
describe the fracture line in a supraondylar fracture
usually extra-articular
i.e. joint not involved and the distal fragment is usually displaced posteriorly
what are the three main complications of supracondylar fractures
-
malunion
- resulting in cubtius varus - damage to median nerve (most common), radial nerve or ulnar nerve
-
ischaemic contrature: brachial artery passes v close to fracture site and can occasionally be damaged or occluded by a displaced fracture
- if reflex spasm of the collateral circulation around the elbow also occurs, there will be ischaemia of the muscles in the anterior compartment of the forearm –> oedema –> compartment sydrome –> further exacerbates ischaemia as it impedes arterial inflow
- if untreated, muscle bellies will undergo infarction
- during repair phase, dead muscle tissue = fibrotic
- fibrotic tissue contracts by myofibroblast activity –> flexion contracture aka Volkmann’s ischaemic contracture
what is Volkmann’s ischaemic contracture
- wrist is typically flexed
- fingers extended at the metacarphalangeal joints
- forearm is often pronated
- elbow is flexed
how do you minimise risk of complications in supracondylar fracture
- exmaine and document neurovascular exam
- radial pulse and capillary re-fill time
management of supracondylar fracture
- depends on your assessment of neurovascular status and how deformed elbow is
- reduce, close and gold it in position w a plaster
- closed reduction and percutaenous pinning (CRPP)
- if reducing, the frature has not restored nerve function, then surgically exploring the nerve and artery may be required
elbow dislocation
- usually occurs when a person, often child, falls on their outstretched hand w the elbow partially flexed
- 2nd most common joint to dislocate after shoulder
- casues major disruption to soft tissues - capsule and ligaments
- pain, loss of function and obvious deformity
why are elbow dislocations so common
- because of the high freqeuncy of falls onto an outstretched hand
why is elbow dislocation most likely to happen mid-flexion
- configuration of the bones contributes most to stability of the elbow in full extension and flexion whereas the stability of the elbow in mid-flexion = more reliant on the ligaments
what type of elbow dislocation is most common
posterior
how are elbow dislocations named
by the displacement of the distal fragment i.e. ulna and radius not humerus
- distal end of humerus is driven through the joint capsule anteriorly
what associated damage occurs in elbow dislocation
- ulnar collateral ligament usually torn
- associated fracture and/or ulnar nerve involvement
what causes anterior elbow dislocation and what is associated with it
< 10%
- usually the result of a direct blow to the posterior aspect of a flexed elbow
- associated fractures of the olecranon are commonly seen due to the degree of force required to dislocate the joint
what is a pulled elbow
sublaxation of the radial head
pulled elbow
- most commonly occurs in 2-5 year olds
- child presents w reduced movement of elbow and pain over the lateral aspect of the proximal forearm
mechanism of a pulled elbow
- when longitudinal traction is applied to the arm w forearm pronated e.g. tugging or swinging child by arms during play
- can also occur during falls or over-reaching for an object
why does a pulled elbow most commonly occur in pronation
- because the annular ligament is taut in supination and more relaxed in pronation so easier for subluxation to occur
- longitudinal traction on the radial head tears the distal attachment of the annular ligament from where it is loosely attached to the neck of the radius
- radial head then displaced distally through the torn ligament
why is a pulled elbow less common w age
annular ligament naturally strengthens as children age
radial head and neck fractures
- one of the most common elbow fractures, easily missed
- usually result from a fall on an outstretched hand when the radial head impacts on the capitellum of the humerus
how does a pt w radial head/neck frature present
pain in lateral aspect of proximal forearm
loss of range of movement
modest swelling
radial head and neck fracture on an x-ray
- ‘fat pad/sail’ sign indicates effusion is present
- in setting of trauma, this is likely to be due to a haemarthrosis (blood in joint) secondary to an intra-articular fracture
- caused by displacement of anterior fat pad = relatively radio-lucent so appears blak on x-ray
why is OA of the elbow relatively uncommon
because of the well matched joint surfaces and strong stabilising ligaments
- as a result, elbow can tolerate large forces w/out becoming unstable = less wear and tear w age
- more commonly seen in men
- manual workers/atheletes
- can be primary or secondary
how would a pt w OA of elbow present
- crepitus
- locking: caused by loose fragments of cartilage in elbow
- swelling occurs relatively late and due to effusion
- osetophytes can impinge on ulnar nerve = paraesthesia +/- muscle weakness
- stiffness of elbow tolerated relatively well by pt, especially loss of extension
X-ray features of OA
Loss of joint space
Osteophytes
Subchondral sclerosis
Subchondral cysts
what is RA
- autoimmune disease in which autoantibodies known as rheumatoid factor attak synovial membrane
- inflamed synovial cells proliferate to form a pannus which penetrates through the cartilage and adjacent bone ==> joint erosion and deformity
- women more commonly affected
- peak onset 40-50 years
what is affected in RA
- metacarphophalangeal/ proximal interphalangeal joints of hands, feet and cervical spine
- can also involve large joints
- autoimmune process also leads to damage to other organs incl eyes, sin, lungs, heart and blood vessels and kidneys
- also commonly have anaemia of chronic disease
what are x-rays features of RA
Loss of joint space
Erosion: juxta-artiucular/marginal bony erosions
Subluxation and gross deformity
Periarticular osteopenia
how is RA predominantly managed
- medically rather than surgically through prescription of disease-modifying
- sometimes in severe cases, surgery required to relieve pain and improve mobility
how does lateral elbow tendinopathy (formerly called lateral epicondylitis) occur - tennis elbow
- prevalence of approx 3% in ppl 40-60 years
- presents w pain at the site of the common extensor origin at the lateral epicondyle
- extensor carpi radialis brevis (ECRBS) muscle normally helps to stabilise the wrist when the elbow is straight
- occurs during a tennis groundstroke
- when ECRB is weakened from overuse, microscopic tears form in tendon where it attaches to lateral epicondyle –> inflamm and pain
- pt advised to modify activities to give tendon opportunity to heal
- disorder is usually self-limiting
- sometimes physio and bracing required or need injections or surgery
where will a pt w lateral elbow tendinopathy feel pain
over thelateral epicondyle during extension of the wrist , especially is this is against resistance
medial elbow tendinopathy - golfers elbow
- formerly called medial epicondylitis
- 10 times less common than lateral elbow tendinopathy
- affects the common flexor origin at the medial epicondyle
- treatment similar to LET and most pt recover fully following simple acitivty modification
what is medial elbow tendinopathy associated w
golfing and with throwing sports that place valgus stress on the elbow
most common site of pathology of medial elbow tendinopathy
interface between the pronator teres and the flexor carpi radialis (FCR) origins
how does a pt w medial elbow tendinopathy present
aching pain over the medial elbow, often notices during acceleration phase of throwing
- pain is produced on resisted flexion or pronation of the wrist
- ulnar nerve symptoms are present in up to 20% of cases due to proximity of the ulnar nerve to the medial epicondyle
what are the three common causes of swellings around the elbow
- olecranon bursitis
- rheumatoid nodules
- gouty tophi
olecranon bursitis (student’s elbow)
inflammation of the olecranon bursa situated between the skin and olecranon process of the ulna
- usually due to repeated minor trauma
- swelling is soft, cystic and transilluminates
- treatment: conservative w compression bandaging +/- aspiration
- hydrocortisone injection needed in some cases
- sometimes due to infection = antibiotics
- occasionally need surgical drainage and wash out under anaesthetic
rheumatoid nodules
commonest extra-articular manifestation of RA
- tend to manifest in smokers and have more aggressive joint disease
- more prone to other extra-articular manifestations of rheumatoid disease incl vasculitis and lung disease
- usually occur over exposed regions that are subject to repeated minor trauma
- can be seen in fingers and forearms
- usually non-tender but overlying skin can ocassionally ulcerate and become infected
- treatment: improve medical control of underlying rheumatoid disease
what is gout
- treatment
- risks
inflamm condition caused by hyperuricaemia
- 90% ppl w hyperuricaemia have difficulty excreting urate
- as uric acid conc inc, supersaturation and precipitation occurs, forming crystals of monosodium urate in synovial cavity of joints, in tendonds and in surrounding tissues
- crystals trigger an innate immune response –> acute inflamm
- treat medically w NSAIDs during acute phase
- once acute attack of gout has resolved , xanthine oxidase inhibitors e.g. allopurinol or febuxostat to reduce production of uric acid and reduce risk of further attacks
- inc the long-term risk of secondary OA due to damage to articular cartilage
gouty tophi
-tophi: nodular masses of monosodium urate crystals deposited in the soft tissues
- late complication of hyperuricaemia and develop in >50% of patients with untreated gout
- usually painless, but complications can include pain, soft tissue damage and deformity, joint destruction and nerve compression
- most common sites are the fingers and the ears, but tophi can also be found in the olecranon bursa and the subcutaneous tissues of the elbow, where they can resemble rheumatoid nodules in appearance
- contain white ‘pasty’ material and, as they enlarge, they work their way towards the skin surface to drain, either forming a** sinus tract or a continuously draining ulcer**
cubital tunnel syndrome
- ulnar nerve passes behind the medial epicondyle of the humerus to enter the forearm so in close proximity to the elbow joint.
- flexor carpi ulnaris muscle has two heads, one head originating from the common flexor origin on the medial epicondyle and a second head originating from the medial margin of the olecranon
- two heads are united by a tendinous arch
- ulnar nerve passes beneath this tendinous arch to enter the cubital tunnel
- area forms a common site for ulnar nerve compression, known as cubital tunnel syndrome
- need to decompress nerve i.e. surgically release it and transpose anterior to medial epicondyle
what does minor trauma to ulnar nerve in cubital tunnel cause
sharp transient pain radiating from elbow to cutaneous ulnar nerve territory (funny bone)
3 muscles to the wrist (posterior forearm)
- extensor carpi radialis longus
- extensor carpi radialis brevis
- extensor carpi ulnaris
3 muscles to fingers (posterior forearm)
- extensor digitorum
- extensor digit minimi
- extensor indicis
3 muscles to thumb (posterior forearm)
- abductor pollicis longus
- extesor pollicis brevis
- extensor pollicis longus
other 3 muscles in posterior forearm
anconeus
supinator
brachioradialis
action of the lumbricals
flex MCPJ
extend IPJ
make an L shape w hand
what are the muscles of the thenar eminence
Opponens pollicis
Abductor pollicis brevis
Flexor pollicis brevis
what are the muscles of the hypothenar eminence
Opponen digit minimi
Abductor digiti minimi
Flexor digit minimi
how are undisplaced fractures of the scaphoid wasit managed
cast for 6-8 weeks
