MSK: Trauma and Overuse, Hand and Wrist Flashcards
What is the most common carpal bone fracture?
Scaphoid
Perilunate dislocations have a 60% association with _____
Scaphoid fractures
Which portion of the scaphoid is the most susceptible to avascular necrosis and non-union?
The proximal pole
Note: Arterial supply to the scaphoid is retrograde (distal to proximal) because approximately 80% of the scaphoid is covered in cartilage.
Avascular necrosis of the proximal scaphoid
Note: Sclerosis is the first sign of avascular necrosis.
What is the most common site of a scaphoid fracture?
Waist (70%)
Concern for scaphoid fracture but radiographs are negative…
Recommend repeat in 7-10 days
Note: 5-20% of scaphoid fractures have negative initial radiographs.
A scaphoid fracture with displacement of more than ____ will likely need surgery (fixation screw)
> 1 mm displacement
What are the components to the scapholunate ligament?
- Dorsal (most important for carpal stability)
- Volar
- Middle
Imaging finding of scapholunate ligament disruption on wrist radiographs
Separation of the scaphoid and lunate by > 3 mm
Scapholunate ligament disruption
Note: If scaphoid and lunate are separated by > 3 mm.
Scapholunate ligament disruption
Note: If scaphoid and lunate are separated by > 3 mm.
Disruption of the scapholunate ligament predisposes to…
DISI (Dorsal Intercalated Segmental Instability)
AND
SLAC (Scaphoid-Lunate Advanced Collapse)
Distal radius and/or carpal fractures are associated with _____ in 10-30% of cases
Scapholunate ligament disruption
Humpback deformity of the scaphoid (due to angulation of the proximal and distal fragments of a scaphoid waist fracture)
Note: This can lead to progressive collapse and non-union and is associated with DISI.
Prieser disease
Atraumatic avascular necrosis of the scaphoid
Avascular necrosis of the scaphoid
Note: The scaphoid is T1 dark.
SLAC wrist
Scaphoid-Lunate Advanced Collapse: When the capitate drops between the scaphoid and lunate due to disruption of the scapholunate ligament (either due to injury or CPPD degeneration)
SLAC (Scaphoid-Lunate Advanced Collapse)
Note: The capitate is dropping between the scaphoid and lunate.
SNAC wrist
Scaphoid Non-union Advanced Collapse: Early radial styloid osteoarthritis due to increased mobility of the distal scaphoid fragment in fracture nonunion (the proximal fragment usually remains attached to the scapholunate ligament, keeping its motion limited)
SNAC (Scaphoid Non-union Advanced Collapse)
Note: Focal osteoarthritis at the raadial styloid due to scaphoid fracture non-union (the distal scaphoid fragment is rubbing against the radial styloid).
Treatment for SLAC/SNAC wrists
- Wrist fusion (better strength, worse flexibility)
- Proximal row carpectomy (better flexibility, worse strength)
The scaphoid and lunate want to rotate away from each other, but are kept in place by the scapholunate ligament. Which ways do the scaphoid and lunate want to rotate (and would if the ligament was disrupted)?
The scaphoid wants to flex (rock to the volar side)
The lunate wants to extend (rock to the dorsal side)
DISI
Dorsal Intercalated Segmental Instability (AKA dorsiflexion instability): When a radial-sided injury disrupts the scapholunate ligament, allowing the lunate to rock dorsally, resulting in dorsiflexion instability and widening of the scapholunate angle
What is the normal scapholunate angle?
30-60 degrees (between the long axis of the scaphoid and the midaxis of the lunate on a lateral/sagittal image)
Note: > 60 indicates DISI and < 30 indicates VISI.
VISI
Volar Intercalated Segmental Instability (AKA volar/palmarflexion instability): When an ulnar-sided injury disrupts the lunotriquetral ligament and the “loose” lunate rocks volar because its being pulled by the scaphoid
Note: This is very rare because lunotriquetral ligament injuries are not common (if you think you see this, its probably actually just a normal variant from wrist laxity).
A scapholunate angle of ______ indicates DISI
> 60 degrees (widening of the scapholunate angle)
Note: Disruption of the scapholunate ligament causes them to angle farther apart.
A scapholunate angle of ______ indicated VISI
< 30 degrees (narrowing of the scapholunate angle)
Note: Disruption of the lunotriquetral ligament causes the lunate to be pulled closer to the scaphoid.
What view can you do to see if there is a scapholunate ligament dissociation?
Clenched fist view (if scaphoid-lunate interval is > 3 mm there is dissociation)
Right scapholunate ligament dissociation
Note: Asymmetric widening of the scapholunate interval on clenched fist view.
Perilunate dislocation
Note: Lunate is still on the radius, but the other carpal bones have dislocated.
Perilunate dislocation
Note: Lunate is still on the radius, but the other carpal bones have dislocated.
Rank the carpal dislocations from least severe to most severe
- Peri-lunate dislocation (least severe)
- Mid-carpal dislocation
- Lunate dislocation (most severe)
Mid-carpal dislocation
Note: Both the lunate and capitate have lost their radial alignment.
Lunate dislocation
Note: Only the lunate has lost its radial alignment.
Perilunate dislocation
Note: The lunate has maintained its radial alignment.
Mid-carpal dislocations are associated with…
Lunotriquetral interosseous ligament disruption
And/or
Triquetral fracture
Lunate dislocations are associated with…
Dorsal radiolunate ligament injury
Lunate dislocation
Note: Disruption of the carpal arcs I and II and the lunate is shaped like a piece of pie.
Trans-scaphoid perilunate dislocation
This indicates that there is a scaphoid fracture and perilunate dislocation
Note: Carpal dislocations can only happen if there is ligamentous injury or carpal bone fractures.
Vulnerable zones theory of carpal dislocation
States that injuries occur through the lesser arc (ligamentous injuries only) or greater arc (associated with carpal bone fractures)
Space of Poirier
A ligament free area in the capitolunate space that is an area of weakness
The synovial space of the radiocarpal joint communicated with the…
Pisiform recess
Note: Excess fluid in the pisiform recess is normal in the setting of a radiocarpal joint effusion.
Are the pisiform recess and radiocarpal joint communicating synovial spaces?
Yes
Are the glenohumeral joint and subacromial bursa communicating synovial spaces?
No, these should not communicate
Note: Communication between these spaces implies a full thickness rotator cuff tear.
Are the ankle joint and common/lateral peroneal tendon sheath communicating synovial spaces?
No, these should not communicate
Note: Communication between these spaces implies a tear of the calcaneofibular ligament.
Are the Achilles tendon sheath and posterior subtalar joint communicating synovial spaces?
No, the Achilles tendon does not have a true synovial tendon sheath
What is the function of the TFCC (triangular fibrocartilage complex)?
It functions as the primary stabilizer and shock absorber of the distal radioulnar joint
What are the 5 components of the TFCC (triangular fibrocartilage complex)?
- Articular disc (triangular fibrocartilage)
- Radioulnar ligaments (volar and dorsal)
- Meniscus homologue
- Ulnar collateral ligament
- Tendon sheath of the extensor carpi ulnaris
What are the most important components of the TFCC (triangular fibrocartilage complex) when planning for surgery?
- Articular disc
- Radioulnar ligaments (volar and dorsal)
How should the TFCC articular disc appear on MRI?
Dark on all sequences
Note: The ulnar and radial attachments often looks intermediate in signal.
What are the two major categories of TFCC injury?
- Acute injuries (usually due to a fall on an extended wrist)
- Chronic degeneration (more common and associated with positive ulnar variance)
TFCC tear
Note: This is the thicker portion representing a radioulnar ligament tear.
Small central tear of the TFCC articular disc (arrow) and a partial thickness undersurface tear (arrowhead)
Arrow
Normal intermediate signal intensity at the ulnar attachment of the TFCC articular disc
Central tear of the TFCC articular disc (typical of a degenerative tear)
Arrow
Avulsion of the ulnar styloid attachment of the TFCC articular disc
Note: The foveal attachment is still intact (arrowhead).
Severe positive ulnar variance with a large central tear of the TFCC articular disc (arrow)
Note: Associated subchondral degenerative changes in the proximal lunate (arrowhead).
Which portion of the TFCC articular disc is less vascularized (and less likely to heal in injured)?
The radial side
Note: The ulnar side is the “red” vascular side.
What is this ulnar variance associated with?
Negative ulnar variance is associated with avascular necrosis of the lunate (i.e. Kienbock disease)
What is this ulnar variance associated with?
Positive ulnar variance is associated with ulnar impaction syndrome (AKA ulnar abutment)
Kienbock disease
Avascular necrosis of the lunate, associated with negative ulnar variance
Note: This commonly occurs in people in their 20s-40s.
Ulnar impaction syndrome (AKA ulnar abutment)
Note: Positive ulnar variance with degenerative changes in the lunate. You would also see tearing of the TFCC.
Kienbock’s disease
Note: Negative ulnar variance with avascular necrosis of the lunate.
Kienbock’s disease
Note: Negative ulnar variance with avascular necrosis of the lunate.
What are the major distal radius fracture types?
- Colles (dorsal angulation)
- Smith (“reverse colles”)
- Barton (intra-articular with radiocarpal dislocation)
- Hutchinson fracture (of the radial styloid)
Colles fracture of the distal radius
Note: Dorsal (“D for border collie Dog”) angulation of the distal fragment.
Elderly male with a Colles distal radius fracture…
Get a DEXA
Colles fractures of the distal radius are associated with…
Ulnar styloid fractures (50% of the time)
Smith fracture of the distal radius
Note: Volar/palmar angulation of the distal fragment (i.e. reverse Colles).
Barton (intraairticular) fracture of the distal radius
Note: Distal radius fracture with intraarticular extension.
Is a Colles fracture of the distal radius intraarticular or extraarticular?
Extraarticular
Is a smith fracture of the distal radius intraarticular or extraarticular?
Extra-articular (85%)
Note: 15% of the time it has intraarticular extension and then is also called a “reverse Barton” fracture.
Is a Barton fracture of the distal radius intraarticular or extraarticular?
Intraarticular
A Smith fracture of the distal radius can lead to…
Carpal tunnel syndrome (if there is residual solar displacement)
Barton (intraairticular) fracture of the distal radius.
Hutchinson fracture
Intraarticular fracture of the radial styloid
This fracture is associated with…
Hutchinson (AKA Chauffeur) fractures are associated with:
- Scapholunate dissociation
- Perilunate dislocation
Hutchinson (AKA Chauffeur) intraarticular fracture of the radial styloid
Note: Barton fracture involves the dorsal or volar radial rim, not the lateral radial styloid.
What is the normal radial tilt of the distal radius?
11 degrees of solar tilt (0-28 acceptable, but should not be dorsally tilted which can happen in distal radius fractures requiring surgical correction)
Note: This should be measured on a true lateral radiograph.
How can you tell if a lateral wrist radiograph is a true lateral
The palmar cortex of the pisiform should be located centrally between the palmar cortex of the scaphoid and capitate
Lister’s tubercle
AKA Dorsal radial tubercle: A bony protrusion on the distal radius that keeps extensor tendons in line
Note: Disruption of this tubercle is what can lead to extensor pollicis longus tendon rupture weeks-months following a distal radial fracture.
There is an increased risk of ____ 3 weeks-3 months after a distal radius fracture
Extensor pollicis longus tendon rupture
Note: This is due to a disruption of the dorsal radial tubercle (AKA Lister’s tubercle).
Is an extensor pollicis longus tendon rupture more common following a displaced or non displaced distal radial fracture?
Non displaced
How long after a distal radius fracture is there an increased risk of extensor pollicis longus tendon rupture?
3 weeks to 3 months after the fracture (especially a non displaced one)
Note: This is due to disruption of the dorsal radial tubercle (Lister’s tubercle) creating a rough and scratchy surface that predisposes to EPL tendon rupture.
How many dorsal (extensor) wrist compartments are there?
6
Note: “5 for each finger and 1 for good luck”.
What tendons are in the 1st extensor compartment of the wrist?
- Abductor pollicis longus
- Extensor pollicis brevis
Note: These are on the radial side and are the ones involved in de Quervain’s tenosynovitis.
De Quervain’s tenosynovitis involves inflammation of what wrist compartment?
Extensor compartment 1 (abductor pollicis longus and extensor pollicis brevis)
What wrist compartment is adjacent to Lister’s tubercle and prone to rupture following a distal radius fracture?
Extensor compartment 3 (extensor pollicis longus)
What are the components of wrist extensor compartment 2?
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
What are the components of wrist extensor compartment 3?
- Extensor pollicis longus
What are the components of wrist extensor compartment 4?
- Extensor indicis
- Extensor digitorum
What are the components of wrist extensor compartment 5?
- Extensor digiti minimi
What are the components of wrist extensor compartment 6?
- Extensor carpi ulnaris
Note: This compartment runs in the groove of the ulnar head.
What are the components of wrist extensor compartment 6?
- Extensor carpi ulnaris
Note: This compartment runs in the groove of the ulnar head.
Which wrist compartment often gets early tenosynovitis in rheumatoid arthritis?
Extensor compartment 6 (extensor carpi ulnaris)
Note: This is the compartment that runs in the groove of the ulnar head.
Where are wrist extensor compartments 1 and 6?
Compartment 1 is on the radial side
Compartment 6 is on the ulnar side (it runs in the groove of the ulnar head)
The carpal tunnel lied deep to what tendon?
Palmaris longus tendon
Note: Immediately deep to this tendon is the transverse carpal ligament (AKA flexor retinaculum) that defines the roof of the carpal tunnel.
What are the four bony prominences that confine the carpel tunnel?
- Pisiform
- Scaphoid tubercle
- Hook of hamate
- Trapezium tubercle
What ligament defines the roof of the carpal tunnel?
The transverse carpal ligament (AKA flexor retinaculum)
What are the contents of the carpal tunnel?
- 4x flexor digiti profundi
- 4x flexor digiti superficialis
- 1x flexor pollicis longus
- 1x median nerve
Does the flexor carpi radialis go through the carpal tunnel?
No
Does the flexor carpi ulnaris go through the carpal tunnel?
No
Does the palmaris longus go through the carpal tunnel?
No
Does flexor pollicis longus go through the carpal tunnel?
Yes
Note: Flexor pollicis brevis does not.
Does flexor pollicis brevis go through the carpal tunnel?
No, it is an intrinsic hand muscle
Note: Extensor pollicis longus DOES go through the carpal tunnel.
What are the clinical manifestations of carpal tunnel syndrome?
- Median nerve paresthesias (1st-3rd digits and the radial aspect of the 4th digit)
- Thenar muscle atrophy
What is being measured here?
Cross sectional area of the median nerve
Note: This is enlarged, suggestive of carpal tunnel syndrome.
Carpal tunnel syndrome
Note: Edema of the median nerve.
Carpal tunnel syndrome
Note: Edema and enlargement/flattening of the median nerve and bowing of the flexor retinaculum.
What are the contents of Guyon’s canal?
- Ulnar nerve
- Ulnar artery/vein
Where does Guyon’s canal run?
Between the pisiform and the hook of hamate (between the palmar carpal ligament and the flexor retinaculum)
Common causes of Guyon’s canal syndrome
- Handlebar injury
- Fracture of the hook of hamate
Clinical manifestations of Guyon’s canal syndrome
- Ulnar nerve paresthesias (pinky and ulnar aspect of the 4th digit)
- Decreased grip strength
Decreased grip strength
Ulnar nerve impingement from a ganglion cyst in the region of Guyon’s canal
Trauma
Subluxation of the extensor carpi ulnaris tendon, indicating a subsheath tear
Note: The ECU tendon (in the 6th extensor compartment) should sit within the groove of the ulnar head.
Vaughan-Jackson syndrome
Sequential rupture of the extensor tendons due to worsening rheumatoid arthritis of the distal radioulnar joint.
Note: The ruptures progress from the ulnar side to the radial side (5th compartment/extensor digiti minimi first, then 4th compartment, 3rd, 2nd, and 1st is last).
Tenosynovitis
Inflammation of the tendon, resulting in increased fluid around the tendon
Common causes of diffuse tenosynovitis
- Myobacterial infection (tuberculous and non-tuberculous)
- Rheumatoid arthritis
Diffuse tenosynovitis, suspicious for mycobacterial infection
Diffuse tenosynovitis involving the extensor tendons, suggestive of rheumatoid arthritis
Horseshoe abscess, suggestive of mycobacterial infection
Note: Distension of the palmar bursae by complex material consisting of numerous low signal foci against a background of fluid signal intensity.
Risk factors for mycobacterium marine infection
- Fisherman
- Sushi chef
Why is infectious tenosynovitis of any flexor tendon a surgical emergency?
The infection can easily spread to the common flexor tendons and increased pressure within the sheath can cause tendon necrosis with horrible outcomes
New mother
De Quervain’s tenosynovitis
Note: Only the first extensor compartment is involved (extensor pollicis brevis and abductor pollicis longus).
De Quervain’s tenosynovitis
Note: Increased fluid in wrist extensor compartment 1.
Positive Finkelstein’s test (pain with passive ulnar deviation of the wrist)…
De Quervain’s tenosynovitis
What imaging finding suggests that De Quervain’s tenosynovitis will resolve with conservative treatment alone?
Absence of an intertendinous septum between the APL and EPB tendons within the 1st extensor compartment
Note: 10% of people have an intertendinous septum and these pts often require surgery in the setting of De Quervain’s tenosynovitis.
Intersection syndrome is classically seen in…
Rowers
Intersection syndrome (tenosynovitis of the 2nd extensor compartment: extensor carpi radialis brevis and longus tendons)
Note: This is due to the first compartment intersecting with the second compartment (classically in rowers).
Drummer’s wrist (tenosynovitis of the 3rd extensor compartment: extensor pollicis longus)
Note: Classically seen in drummers.
Drummer’s wrist involves tenosynovitis of…
The 3rd compartment: extensor pollicis longus
Bennett fracture of the base of the first metacarpal
Note: Bennett fracture is intraarticular and not comminuted. A comminuted intraarticular fracture here is termed “Rolando”.
What causes the dorsolateral dislocation in a Bennett fracture?
The pull of the abductor pollicis longus tendon
Rolando fracture (comminuted fracture of the base of the first metacarpal)
Note: There is complete dissociation of the first carpo-metacarpal joint (in a non-comminuted Bennett fracture, part of the CMC joint remains attached).
Gamekeeper’s thumb (avulsion fracture at the base of the first proximal phalanx)
Note: This is associated with ulnar collateral ligament disruption (i.e. possible steer lesion).
Next step
MRI (to look for a Stener lesion)
Note: This is gamekeeper’s thumb (avulsion fracture at the base of the first proximal phalanx). Do NOT get stress views as this might cause a Stener lesion.
What ligament gets disrupted in gamekeeper’s thumb?
The ulnar collateral ligament gets disrupted
Note: This could be associated with a Stener lesion, which requires surgery.
Stener lesion
When a torn ulnar collateral ligament (which is normally deep to the adductor pollicis tendon) slips superficial to this tendon, preventing it from healing down normally (this requires surgical correction)
Note: This can be a complication of gamekeeper’s thumb (avulsion fracture of the base of the first proximal phalanx).
Gamekeeper’s thumb classically occurs in…
Skiers
Note: This is an avulsion fracture of the first proximal phalanx.
Hand ultrasound
Think trigger finger (stenosing tenosynovitis due to overuse/repetitive trauma)
Note: Thickening of the hypoechoic sheath.
What are common locations for stenosing tenosynovitis?
- Finger flexor tendons (i.e. trigger finger)
- Flexor hallucis longus (around the ankle in pts with os trigonometry syndrome)
Tuft fracture, recommend clinical correlation for nailed injury (which would then be considered an open fracture, requiring antibiotics)
