6: Elbow and Forearm Flashcards
1
Q
superficial muscles of anterior compartment of forearm
A
flexor carpi ulnaris
palmaris longus
flexor carpi radialis
pronator teres
2
Q
intermediate muscles of anterior compartment of forearm
A
flexor digitorum superficialis
3
Q
deep muscles of anterior compartment of forearm
A
flexor pollicis longus
flexor digitorum profundus
pronator quadratus
4
Q
actions associated w anterior forearm
A
proantion of forearm
flexion of wrist
flexion of fingers
5
Q
innervation of anterior forearm
A
mostly median nerve
- except for flexor carpi ulnaris and medial 1/2 of flexor digitorum profundus which are ulnar
6
Q
arterial supply of anterior forearm
A
ulnar and radial artery
7
Q
origin of all superficial muscles anterior forearm
A
common tendon which arises from medial epicondyle of humerus
8
Q
prosection of superficial anterior forearm
A
9
Q
prosection of intermediate layer of anterior forearm
A
10
Q
prosection of deep layer of anterior forearm
A
11
Q
borders of cubital fossa
A
lateral: medial border of brachioradialis
medial: lateral border of pronator teres
superior: horizontal line between epicondyles of humerus
12
Q
roof of cubital fossa
A
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
13
Q
floor of cubital fossa
A
proximally: brachialis
distally: supinator
14
Q
how do conditions of the elbow present
A
- pain
- swelling
- restriction of movement
- deformity
- different conditions common at different ages
15
Q
supracondylar fracture
A
- 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
16
Q
classification of supracondylar fractures
A
17
Q
describe the fracture line in a supraondylar fracture
A
usually extra-articular
i.e. joint not involved and the distal fragment is usually displaced posteriorly
18
Q
what are the three main complications of supracondylar fractures
A
-
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
19
Q
what is Volkmann’s ischaemic contracture
A
- wrist is typically flexed
- fingers extended at the metacarphalangeal joints
- forearm is often pronated
- elbow is flexed
20
Q
how do you minimise risk of complications in supracondylar fracture
A
- exmaine and document neurovascular exam
- radial pulse and capillary re-fill time
21
Q
management of supracondylar fracture
A
- 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
22
Q
elbow dislocation
A
- 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
23
Q
why are elbow dislocations so common
A
- because of the high freqeuncy of falls onto an outstretched hand
24
Q
why is elbow dislocation most likely to happen mid-flexion
A
- 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
25
what type of elbow dislocation is most common
posterior
26
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
27
what associated damage occurs in elbow dislocation
- ulnar collateral ligament usually torn
- associated fracture and/or ulnar nerve involvement
28
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
29
what is a pulled elbow
sublaxation of the radial head
30
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
31
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
32
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
33
why is a pulled elbow less common w age
annular ligament naturally strengthens as children age
34
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
35
how does a pt w radial head/neck frature present
pain in lateral aspect of proximal forearm
loss of range of movement
modest swelling
36
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
37
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
38
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
39
X-ray features of OA
**L**oss of joint space
**O**steophytes
**S**ubchondral sclerosis
**S**ubchondral cysts
40
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
41
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
42
what are x-rays features of RA
Loss of joint space
Erosion: juxta-artiucular/marginal bony erosions
Subluxation and gross deformity
Periarticular osteopenia
43
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
44
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
45
where will a pt w lateral elbow tendinopathy feel pain
over thelateral epicondyle during extension of the wrist , especially is this is against resistance
46
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
47
what is medial elbow tendinopathy associated w
golfing and with throwing sports that place valgus stress on the elbow
48
most common site of pathology of medial elbow tendinopathy
interface between the pronator teres and the flexor carpi radialis (FCR) origins
49
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
50
what are the three common causes of swellings around the elbow
- olecranon bursitis
- rheumatoid nodules
- gouty tophi
51
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
52
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
53
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
54
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**
55
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
56
what does minor trauma to ulnar nerve in cubital tunnel cause
sharp transient pain radiating from elbow to **cutaneous ulnar nerve territory** (funny bone)
57
3 muscles to the wrist (posterior forearm)
- extensor carpi radialis longus
- extensor carpi radialis brevis
- extensor carpi ulnaris
58
3 muscles to fingers (posterior forearm)
- extensor digitorum
- extensor digit minimi
- extensor indicis
59
3 muscles to thumb (posterior forearm)
- abductor pollicis longus
- extesor pollicis brevis
- extensor pollicis longus
60
other 3 muscles in posterior forearm
anconeus
supinator
brachioradialis
61
action of the lumbricals
flex MCPJ
extend IPJ
make an L shape w hand
62
what are the muscles of the thenar eminence
**O**pponens pollicis
**A**bductor pollicis brevis
**F**lexor pollicis brevis
63
what are the muscles of the hypothenar eminence
**O**pponen digit minimi
**A**bductor digiti minimi
**F**lexor digit minimi
64
how are undisplaced fractures of the scaphoid wasit managed
cast for 6-8 weeks
65
