Upper limb 13/01/2023 Flashcards
What are the Tendons and Ligaments of the Fingers?
Extensor Tendons- Insert into the dorsal surfaces at the base of each phalanx
Collateral Ligaments- Found in all phalanges and extend from the lateral and medial margins of each metacarpal and each phalanx, bridging across the joint, and inserting into the same margin on the base of the adjacent phalanx
Volar Plate- On the palmar aspect of each phalangeal joint and attaches to the base of the adjacent phalanx
Gamekeeper’s Thumb / Skier’s Thumb
A rupture of the ulnar collateral ligament caused by abduction and hyperextension injury of thumb
Patient will be unable to grip or pinch
Commonly bone remains intact but will occasionally see a bony fragment at the site of the avulsion
Can conduct x-ray examination with stress applied to thumb (under orthopaedic control) – will see a widened joint space when stress is applied
Surgical repair often required
Bennett’s Fracture
at base of the 1st metacarpal which extends into the joint surface with dislocation at the carpo-metacarpal joint
Forced abduction injury
Abductor Pollicis Longus muscle – originates on the posterior surface of the ulna and radius and inserts into the first metacarpal
Responsible for the abduction of thumb and hand
Metacarpal is pulled dorsally and laterally by the abductor pollicis longus muscle of the forearm
Common football injury
ORIF
Carpo-Metacarpal Dislocations
Most commonly occur in 4th and 5th joints
Often has an associated # at base of the metacarpal
On DP Hand would see a loss of the normal joint space at base of MC
Oblique x-ray normally demonstrates dislocation more clearly
Patient presents for x-ray with ?Fracture of 5th MC
Mechanism of injury?
Punch
Standard projections
DP and DP oblique
What other projections could we do to demonstrate this fracture?
Lateral
Posterior Oblique / AP Oblique
Posterior Oblique / AP Oblique hand positioning?
From the AP position, rotate the hand 45° internally
Centre at the head of the 5th MC, angling to the head of the 3rd MC
What’s a Colle’s fracture?
Colle’s – extra articular transverse facture of the distal radius, with dorsal (posterior) angulation of the distal fracture fragments
Posterior displacement of the distal fragment (Colles’) – MOI FOOSH
Whats a smith’s fracture?
Smith’s – extra articular transverse facture of the distal radius, with volar (palmer) angulation of the distal fracture fragments (reverse Colles’s)
Anterior displacement of the distal fragment (Smith’s) – Fall on inwardly positioned hand
Impacted undisplaced fracture, x-ray appearance
Impacted undisplaced fracture – will see a very slight increase in bone density (sclerotic line)
Torus fracture. x-ray appearance
Torus fracture (blue arrow) – will show as a slight ripple in the cortex, common in children
What is Compartment Syndrome?
A painful and potentially serious condition caused by bleeding or swelling within an enclosed bundle of muscles
Can be caused by extravasation of contrast media injection
Acute Compartment Syndrome will cause intense pain and tightness due to stretching of the affected muscle(s) and a tingling or burning feeling in the skin
Must be treated urgently – normally with a surgical fasciotomy – otherwise permanent muscle and nerve damage can occur
Causes white on the image
What is Carpal Tunnel Syndrome
Swelling of one or more structures within the carpal tunnel causing compression of the median nerve
Intermittent tingling, numbness, pain and weakness
Most frequently affects dominant hand
Causes;
Congenital
Trauma
Repetitive stress
Tumour/cyst
Arthritis
First line investigation – nerve conduction study
When imaging is required;
MRI – to assess whether there are tumours or lesions as a cause
Ultrasound – also can demonstrate lesions
Carpal Tunnel X-ray positioning?
Positioning Criteria:
Patient stands with back to table, resting palm of hand on IR on the table
Centre along the line of the forearm at the point between the pisiform and ridge of the trapezium
VCR perpendicular to IR
This is a very specialised and slightly outdated projection, yet it is still important to know how to perform it, especially if you don’t have a CT scanner readily available.
Just remember will cause the significant patient pain if not performed correctly, It is best to demonstrate to the patient physically what you plan to do before making them perform it, this way they are not in discomfort for long.
The scaphoid projections?
4 different projections as standard (PA, Lateral, Oblique (PA +/- AP), Angled PA with ulnar deviation
Blood Supply and Healing of scaphoid fracture
Scaphoid has a blood supply from only one direction (the volar aspect)
A fracture in the proximal aspect of the bone will leave the fragment with no blood supply
Poorer healing (union) rate the closer # occurs to the proximal pole of the scaphoid
Blood blood supply comes from distal end in
Tubercle, distal, mid-portion, proximal
Scaphoid x-ray appearance
90% of scaphoid fractures heal well if treated early however they may not be immediately seen on an x-ray
A bulging fat pad may indicate oedema or bleeding around scaphoid indicating injury
This sign is best seen on PA wrist with ulnar deviation however it is not very specific
Fractures only identified in 50% of patients with positive fat pad sign on subsequent MRI scans
CT scaphoid
Indicated if suspicion of fracture still exists but not visualised or if further information is required about the fracture
Allows good assessment of bone but not soft tissue
Can exclude fracture
A slice thickness of 1-2mm is typical
Multiplanar reconstructions commonly done, with an addition of an oblique sagittal plane through the long axis of the scaphoid
Not reformatted in True Anatomical Position but to the anatomical plane of the scaphoid
Bone Scintigraphy Three Phases:
Flow Phase
2-5 second images are obtained for 60 seconds after the injection
Demonstrates perfusion which characterises the blood flow to a particular area
Blood Pool Phase
5 minutes after the injection
Demonstrates how blood pools in the area as opposed to blood flow
Inflammatory conditions or problems with blood supply (e.g. AVN)
Delayed Phase
2-4 hours after injection
Much of the radionuclide will have been excreted from body in urine
Uptake will be measured depending on blood flow and rate of new bone formation
Carpel dislocations carpel arcs information
There are 3 carpal arcs;
Smooth curve outlining the proximal convexities of the scaphoid, lunate and triquetrum
Traces the distal concave surfaces of the same bones
Follows the main proximal curvatures of the capitate and hamate
Lines should be parallel and unbroken
Width of joints between neighbouring carpal bones should be 1-2mm
A break in one of the arcs indicates # or disruption of a ligament causing subluxation or dislocation
Lunate Dislocation information
Most severe of carpal instabilities
Commonly associated with a transverse fracture of the scaphoid
Involves all of the intercarpal joints and disrupts most of the major carpal ligaments
Volar dislocation and forward rotation of lunate
The concave distal surface of the lunate moves to face anteriorly to the palm of the hand
Will appear pyramid shaped on the PA projection
Peri-Lunate Dislocation information
The lunate remains in position but the capitate and neighbouring carpal bones have moved out of position
Injury is 2-3 times more common than a lunate dislocation
Commonly associated with a scaphoid fracture (75%)
Also important to check that there is no # of the ulnar styloid process
Midcarpal Dislocation information
When the lunate and capitate dislocate from their position
Again, often seen with an associated scaphoid fracture
Standard Projections for elbow
LATERAL VIEW
Capitulum and trochlea are superimposed
Olecranon seen in profile
Posterior fat pad is not visible but anterior may be closely applied to humerus
Lateral - There are two fat pads situated anteriorly and posteriorly to the distal humerus, and in contact with the joint capsule (seen as black)
AP VIEW
Olecranon not seen clearly
Laterally, the capitulum articulates with the radial head
Medially the trochlea articulates with the ulna
Imaging the Trauma Elbow
Have the radius/ulna and humerus equal angle above the detector
OR
Humerus in contact with IR
20 degrees distal angle will throw some of forearm onto the cassette
Centre midway between humeral epicondyles, main area of interest distal humerus
OR
Forearm in contact with IR
VCR or 20 degrees proximally
Centre 2.5cm distal to the crease of elbow
Main area of interest radial head
Infero-superior Axial projection For imaging the distal humerus
Infero-superior Axial
For imaging the distal humerus
Centre 5cm distal to olecranon with angle of 30 degrees towards shoulder
Image will show a fracture of the lateral condyle (if present)
Can also check general alignment and demonstrate gross injury
Supero-inferior Axial projection for the proximal forearm
Supero-inferior Axial
For imaging the proximal forearm
Centre 5cm proximal to olecranon with angle of 30 degrees from vertical
Bones should be superimposed over humerus with the olecranon/trochlea articulation visible
Elbow lines
Anterior humeral line: a line traced along the anterior cortex of the humerus where at least one third of the capitellum is anterior to it. Less than one third then is likely to be a supracondylar fracture
Radiocapitellar line: a line that runs along the radius through the neck and head that should pass through the capitellum; if the line does not pass through then a radial head dislocation is likely (note – this true for lateral views, and does not always hold true when there is fracture to the shaft)
Radial Head Fractures types
Split
Tilt
Shear
Crush
Result of a FOOSH injury – force is transmitted up the arm pushing the radial head into the capitulum
Patient will experience swelling, tenderness and decreased ROM
Patterns of injury in radial head fractures
Can be isolated or combined with injury to surrounding structures (e.g. dislocations)
Visualising Radial Head Fractures
Externally rotated AP elbow projection can be conducted to visualise the whole of the radial head by opening up the joint space between the proximal radius and ulna
FAT Pad Sign info
Soft tissue sign in cases of intra-articular injuries of the elbow
There is normally a fat pad present within the joint capsule but outside the synovium
Anterior and Posterior
Anterior fat pad not typically seen on a lateral elbow x-ray
Upon injury, intra-articular haemorrhage causes distension of the synovium and forces the fat pad from the fossa
Note: normal fat pads do not exclude a fracture, if injury causes the elbow joint capsule to rupture then the fluid (blood, fat etc.) will drain from the joint and raised fat pads won’t be visualised
A raised fat pad doesn’t indicate a fracture, just an injury
Axial vs Y-view shoulder
pros and cons
Axial
Demonstrates a view as if looking into patient’s armpit
Easy to orientate
Abduction of the arm may be painful which can affect diagnostic quality of image if positioning not correct
Y-View
Does not cause (as much) discomfort for patient
Is technically easier to obtain
Easy to interpret
Mechanisms of Injury for shoulder
FOOSH – Fractures
Direct force – Fractures and dislocations
Fractures common to;
Neck of humerus and greater tuberosity
Head of humerus and glenoid rim (associated with anterior dislocations)
Clavicle
Neck and head of numerus fracture mechanisms
FOOSH
Normally related to insertions of the rotator cuff
Clavicle fractures mechanisms
FOOSH
Fall onto lateral shoulder
Direct force (rare)
Clavicle:
Occurs in both adults and children
In adults immobilisation to allow for healing
Intervention needed with children as they are unlikely to keep arm immobilised like an adult would (deformity common if not kept still)
Dislocations of Acromio-Clavicular Joint (ACJ)
Abducted humerus and direct downwards force
Requires an AP for assessment
In cases where it is uncertain from the AP if an injury is present, a patient may be required to have further imaging of both the affected and unaffected sides with them holding weights for comparison
Normal joint width space less than 10mm
If the inferior surfaces of the acromion and clavicle are not in alignment (e.g. a step is apparent) then there is likely a subluxation or dislocation or the ACJ
