MSK - Trauma Flashcards
Where should contrast be injected in MR arthrogram in suspected triangular fibrocardilage tear?
Dorsal approach to radiocarpal compartment
If contrast leaks from radiocarpal compartment to the distal radioulnar compartment - this confirms presence of a tear
What is the arcuate sign?
The arcuate sign is the elliptical shaped avulsed bony fragment adjacent to the fibular styloid process representing an avulsion fracture of the fibular styloid.
The arcuate ligament attaches to fibular styloid and together with the LCL and lateral joint capsule forms the Arcuate complex
What is O’Donoghues triad?
MMA
Happens during football injuries where there is valgus stress on a flexed knee (known as clip and pivot shift injury)
- MCL injury (shift)
- ACL injury (pivot)
- Medial meniscus injury (remember meniscus is attached to MCL)
((lateral meniscus injuries are actually more common than medial in this type of injury))
What are pelligrini stieda lesions?
Where are they located?
Located within Medical collateral ligament
Tiny fragments of calcification that have formed in MCL following trauma
Seen superomedially to femoral condyle
- Appears weeks after injury
- Most patients are asymptommatic
What is Sinding-Larsen-Johannsen disease?
Affects 10 - 15 year olds
Affects proximal end of patellar tendon as it inserts into inferior patella
- patellar tendon thickening
- -possible stranding in hoffas fat pad*
Similar to osgood schlaters - fragmentation at patellar tendon insertion at tibial tuberosity
Below images demonstrates both
Different avascular necrosis names
Injury to what wrist ligament causes midcarpal dislocations?
Lunotriquetral ligament
Lunate dislocation is a result of dorsal radiolunate injury
Injury to capitolunate ligament results in perilunate dislocations
What is a reverse Segond fracture?
RPM
Avulsion of the medial tibial plateau (after external rotation injury)
Associated with:
-PCL injury
-Medial meniscus tear
What is a segond fracture?
Avulsion of the lateral tibial plateau
Associated with ACL injury
What is most common type of ankle injury?
Supination external rotation - results in low fibular fracture (sometimes medial malleolar fracture)
Which part of scaphoid is most susceptible to AVN?
What is earliest sign of AVN?
Blood flow to scaphid is retrograde distal to proximal
Therefore proximal scaphoid is most susceptible
Most common site of fracture is the waist
First sign of AVN is sclerosis
What is a sign of scapholunate ligament disruption/tear?
Assocaited with 30% of distal radius fractures
A gap of >3mm between the scaphoid and lunate
Terry thomas sign
SLAC and SNAC wrist
What are they and whats difference?
SLAC
Scapholunate advanced collapse due to:
- injury (scapholunate dislocation)
- CPPD degeneration
- The scapholunate ligament prevents rotation of the scaphoid during flexion*
- When ligament is damaged:*
- *-scaphoid will tilt**
-radioscaphoid space will narrow
-capitate will migrate proximally
SLAC and SNAC are commonest causes of wrist arthritis
SNAC of wrist
What is it?
Scaphoid Non union advanced collapse
There is scapholunate dislocation due to scaphoid fracture
Results in significant radioscaphoid arthritis
What is DISI and VISI?
It has to do with issue of the scapholunate ligament and scaphoid and lunate
The scapholunate ligament has 3 parts:
-dorsal (lunate like to tilt dorsally
-volar (scaphoid likes to tilt volar)
-middle
With a ligament injury the carpal bones want to move
DISI (Dorsal intercalated segemental instability)
Essentially dorsiflextion instability
Due to a RADIAL SIDED injury:
- -scaphoid fracture*
- -distal radius fracture*
- -radius malunion*
- -ligamentous injury*
- Injury of the scapholunate causing dorsal tilt of the lunate (no support from scaphoid as its ligament is damaged)*
- scapholunate angle on the lateral will be >60 (sign of scapholunate dislocation)
-capitalunate angle on lateral >30 (capitate will be displaced posteriorly compared to radius)
As a result of trauma usually
VISI
What is it?
Volar flexion injury
MUCH LESS common than DISI
Due to injury on the ULNAR SIDE:
- can be found in uninjured wrists however and often seen as a normal variant in patients with wrist laxity
- Narrowing of the scapholunate angle (<30) with VOLAR tilt of both the SCAPHOID and LUNATE*
- Dorsal tilt of the CAPITATE and HAMATE*
Lunate and perilunate dislocations
What fracture is peri-lunate associated with?
In peri-lunate dislocate the lunate stays PUT
Perilunate is associated with SCAPHOID fracture
Triangular fibrocartilage complex
Where is is located?
What is function?
A complex of ligaments that supports the wrist
Located between ulna, lunate and triquetrum
Shape can vary depending on the ulnar variance
Positive ulnar variance: thinner and arc shaped TFC
Negative ulnar variance: thicker and shorter with more horizontal lie
Triangular fibrocartilage injury
What symptoms will patient present with?
Traumatic injuries are symptommatic whereas degeneration is asymptommatic (tends to be ass with positive ulnar variation)
Presenting features include:
- -ulnar sided wrist pain*
- -pain on pronation and supination*
- -pain on ulnar deviation*
Look for ulnar styloid fracture.
Has alot of potential assoiated ligamentous injuries e.g. radioulnar ligament, lunotriquetral ligaments
TFC injury will appear as high T2 signal extending to surface of ulna
TFC degeneration are high T2 but WONT extend to the joint
Healing
Ulnar side of TFC (medial) is vascular so more likely to heal and surgery is an option
Central tears are avascular and less likely to heal
What is ulnar impaction syndrome?
Essential where there is positive ulnar variance and the ulna smashes into the lunate causing degeneration and TFC injury
- subchondral sclerosis cysts of ulna and lunate
- Can be a result of distal radius fracture with shortening*
What is Kienbocks?
AVN of the lunate in people aged 20-40’s
Assocaited with NEGATIVE ulnar variance
-Signal drop out on T1
What is a Barton fracture?
This is a type of intraarticular distal radial fracture
Can be either dorsal or volar extension to the joint
Associated with radiocarpal joint dislocation
Dorsal angulation
What is considered normal angle on the lateral view?
Normal angle is 11 degrees
What is contained within carpal tunnel?
Defined by 4 bony prominence: PSHT
- pisiform
- scaphoid tubercle
- hamate hook
- trapezium tubercle
Within tunnel - 10 things
- Flexor pollicis longus (FPL) x1*
- Flexor digitorum superficialis (FDS) x 4*
- Flexor digitorum profundus (FDP) x 4*
- Median nerve*
Where does DeQuervans tenosynovitis affect?
Classically seen in new mum holding a baby
Repetitive strain injury
Affected tendons
- Extensor pollicis brevis (EPB)*
- Abductor pollicis longus (APL)*
Intersection Syndrome
Seen in rowers
Affects the extensor carpi radialis, brevis and longus
Due to first extensor tendon intersecting the second
Small fractures summary
Bennetts
Base of thumb fracture
NOT comminuted
Rolandos
Base of thumb fracture
Comminuted
Gamekeepers Thumb
Fracture at base of first phalanx thumb
Assocaited with ulnar collateral ligament disruption
DONT do stress views
Monteggia vs Galeazzi fracture
MUGR
(Monteggia Ulnar Galeazzi Radius)
Monteggia
Proximal ulna fracture with anterior dislocation of the radial head
Galeazzi
Radial shaft fracture with anterior dislocation of the distal ulna
What is cubital tunnel syndrome?
Compression of the ulnar nerve in a tunnel on the inside of the elbow
A common cause is an accessory aconeus
- Aconeus is normally located on the radial side (lateral)*
- An accessory aconeus can also be seen on the medial side and compress on the ulnar nerve*
- -will orgiginate at medial epicondyle and insert into olecranon*
Lateral epicondylitis vs medial
Lateral = tennis elbow
extensor carpii radialis brevis
Medial = golfers elbow (less common)
What fractures associated with elbow disloation?
Coronoid process
Radial head
External vs internal rotator cuff impingement
Whats the difference?
External
Otherwise known as subacromial impingement
Causes:
- -Hooked acromion (Type 3 Acromion)*
- -Subacromial osteophyte*
- -Subcoracoid impingement (of the subscapulars tendon)*
Internal
Inpingement of rotator cuff at internal deep part at glenoid labrum and humeral head
- Posterior superior (site on glenoid where impingement occurs) - occurs in abduction external rotation where juction of supra and infra tendons contact posterior superior glenoid*
- Anterior superior - biceps and subscap hit anterior superior glenoid rim (arm extended horiz in abduction)*
What is a SLAP tear?
Superior labral anterior posterior tear
Tears involve the superior glenoid labrum where long head of biceps inserts (can extend into tendon)
- can be seen after fall onto outstretched arm
- -seen in swimmers*
NOT associated with instability