Hand & Wrist Flashcards
What is a radiocarpal dislocation? How does it differ from perilunate dislocations?
Dislocation of the radius from the carpal bones. Differs from perilunate dislocation because the carpal bones are still aligned
Which direction do radiocarpal dislocations commonly occur?
Dorsal > volar dislocation (of the carpus on the radius)
What is the primary soft-tissue restraint against volar translation of the carpus?
Short radiolunate ligaments
What are the origin and insertions of the short radiolunate ligaments?
O: Radius on the ulnar, volar margin of the lunate facet
I: volar surface of the lunate
What is the main restraint of ulnar translation of the carpus?
Radioscaphocapitate ligament
What is the classification system of radiocarpal dislocation?
Dumontier:
Group 1: radiocarpal fracture-dislocation that is purely ligamentous or involves only a small cortical avulsino fracture off the radius
Group 2: radiocarpal fracture-dislocation associated with a large radiostyloid fracture fragment (involving at least 1/3 of the scaphoid fossa)
Are group 1 or group 2 radiocarpal dislocations harder to treat? Why?
Group 1 are harder to treat
- These represent global ligamentous disruptions resulting in multidirectional instability
- Unlike group 2’s, they DO NOT have any bony fragments attached to ligaments that will be more easily fixed with surgery
What are the commonly avulsed fracture fragments in radiocarpal dislocation?
- Radial styloid avulsion by the radioscaphocapitate ligament
- Volar lunate facet by the short radiolunate ligament
- Ulnar styloid
What are the 3 main groups of wrist ligaments?
Palmar radiocarpal ligaments
Ulnar carpal ligaments
Dorsal ligaments
What comprises the palmar radiocarpal ligaments?
Radioscaphocapitate ligament
Long radiolunate ligament
Short radiolunate ligament
Radioscapholunate ligament
What comprises the dorsal ligaments of the wrist?
Dorsal radiocarpal ligament
Dorsal intercarpal ligament
What comprises the ulnar carpal ligaments of the wrist?
Ulnolunate ligamnet
Ulnotriquetral ligament
Ulnocapitate ligament
Describe dorsal versus volar perilunate dislocations:
Dorsal: dorsal dislocation of the capitate with respect to the lunate while the lunate stays in good position
Volar: This is the final stage of injury. The capitate has reduced and the lunate is dislocated volarly
What is the classification of perilunate dislocations?
Mayfield Classification Stage 1: Scapholunate dissociation Stage 2: + Lunocapitate dissociation Stage 3: + Lunotriquetral dissociation Stage 4: Lunate dislocation
What are the common directions of perilunate dislocations?
Volar > dorsal
What is the pathomechanical force of perilunate dislocation?
Wrist extension, ulnar deviation and intercarpal supination
Which way does a perilunate injury propogate?
Ulnarly, with the initial injury coming at the scapholunate interval
- Scapholunate interval -> Space of Poirier/capitolunate articularion -> lunotriquetral articularion -> failure of dorsal radiocarpal ligament
In the final stage of lunate dislocation, where does the lunate dislocate into?
Carpal tunnel
What are greater and lesser arc perilunate injuries?
Greater arc: Injuries that involve bone
Lesser arc: Injuries that are purely ligamentous
What is a translunate arc injury?
Rare injury involving a perilunate dislocation with a fracture of the lunate itself
What are the arcs of Gilula?
Refers to the curves produced by the anatomic alignment of the carpal row bones
Are the volar or dorsal radiocarpal ligament stronger?
Volar
This is why most radiocarpal dislocations occur dorsally
What does VISI stand for?
Volar intercalated segmental instability
What is the pathomechanism of VISI?
Disruption of the triquetrum, due to distuption in lunotriquetral ligament complex
Leads to hyperflexion of the radio-luno-capitate alignment, where the lunate and capitate have excessive flexion
What does DISI stand for?
Dorsal intercalated segment instability
What is the pathomechanism for DISI?
Disruption of scaphoid leading to excessive dorsiflexion of the luno-triquetral complex.
Either: scaphoid fracture or disruption of scapholunate ligament
How do you define a DISI injury (dorsal intercalated segmental instability)?
Scapholunate angle >70 deg
What is the second most fractured carpal bone?
Triquetrum
Name the indication for surgery in a scaphoid fracture?
Displacement > 1mm Radiolunate angle >15 deg Scapholunate angle >60 deg Humpback deformity Nonunion
What is the 0 degree capitolunate angle?
Straight line drawn 3rd MC shaft, capitate, lunate and radial shaft with the wrist in neutral should be a straight line (0 deg)
What is the normal scapholunate angle?
45 deg
range 30-70deg
What are the ligaments of the wrist?
Extrinsic: Bridge the carpal bones from forearm to metacarpal
Intrinsic: Originate and insert in the carpal row
What wrist ligaments are stronger, volar or dorsal?
Volar
What are the most important intrinsic ligaments of the wrist?
Scapholunate interosseous ligament
Lunotriquetral interosseous ligament
-Think perilunate injury - these are the first few to be damaged
What makes up the volar wrist capsule?
Extrinsic wrist ligament
- That’s why it’s a bad idea to go volar to see the capsule - b/c it destabilizes these ligaments
- So if you need to see the joint, go dorsal
What are the boundaries of the flexor zones of the hand?
I: Distal to the FDS
II: Distal to the palmar crease to the FDP
III: Palm
IV: Carpal tunnel
V: Proximal to the carpal tunnel (wrist to forearm)
What is No Man’s Land?
Flexor zone II
- Historically had poor outcomes, but now better b/c of better movement rehabilitation protocols
What are the boundaries of the flexor zones of the thumb?
TI:
TII:
TIII:
What are the most important pulleys in the fingers/thumb?
A2, A4 in fingers
Oblique in thumb
What is the most important technical factor in repair of tendons?
of stands crossing gap more important than # of grasping loops
- 4-6 strands crossing gap is adequate for early ROM
- Epitendinous sutures add 20% strength and also improve gliding
- Ideal suture purchase is 10mm from tendon edge
- Core sutures placed dorsally are stronger
Name 3 early movement protocols for the hand:
Duran:
- Low force, low excursion
- Active finger etension w/ patient assisted passive flexion
Klienert:
- Low force, low excursion
- Active finger extension, dynamic splinting-assisted passive flexion
Mayo synergistic splint:
- Low force, high tendon excursion
- Adds active wrist motion, which increases tendon excursion the most
What are the 8 tendon transfer principles?
- Preoperative correction of contractures
- Adequate strength of transferred muscles
- The transferred muscle will lose one grade of strength
- Avoid transferring previously denervated muscles
- Match donor excursion—may increase amplitude of excursion by increasing the number of joints a transferred tendon crosses or with more dissection of muscle
- Straight line of pull
- One tendon, one function
- Use synergistic muscle groups
- Like finger flexion and wrist extension
- Use expendable donors
- Avoid post-operative adhesion formation
- Delay transfers until wounds are well healed and scars are soft
- Use natural tissue planes and avoid
What are the accepted excursion distances of the wrist flexors and extensors, finger and thumb extensors (EPL) & finger flexors?
Wrist flexors & extensors: 33mm
Finger and thumb extensors: 50mm
Finger flexors: 70mm
What is the rerupture rate of flexor tendon repair?
15-25%
What is the management of a re-ruptured flexor tendon?
If 1cm of scar, tendon graft
- If sheath intact & allows passage of a pediatric urethral catheter/vascular dilator: primary tendon grafting
- If sheath is collapsed, place Hunter rod and perform staged grafting
X-rays:
Normal Scapholunate Angle
Normal SL interval
Normal Lunate alignment
Normal SL Angle =
SLAC wrist classification
Watson classification
Stage I: arthritis between radial styloid and scaphoid
Stage II: arthritis extending into scaphoid facet
Stage III: Above + lunocapitate joint involved
Scapholunate Disruption Classficiation
Geissler classification: based on arthroscopic evaluation
I: attenuation,
II
III
IV: Drive through sign with a 2.7mm scope
