Hand Flashcards
What is the volar plate?
Fibrocartilagenious struture that overlies the volar aspect of the IP joints
Tough and thick, main purpose us to prevent hyperextension
What is cascade sign? Why does this work anatomically?
With arm flexed, palm supinated, partially closure of the hand should demonstrate gradual increase in flexion from radial to ulnar
If askew demonstrated injury with rotational deformity in digits
remember - the strongest movements you do with your hands involve grip and we want them to be the most stable. So when your fingers are extension the collateral ligaments are loose and you have more ROM. When you flex from 0 to 90 they go tight and less ROM.
This is why we splint with 90 flexion - otherwise when loose they contract
Which carpals are more fixed and why?
D1-D3 are more fixed. D4 and D5 have up to 25 degrees of movement (allows the hand to bend in and improve grip and better opposition of thumb)
What are the four arches in the hand?
Proximal, distal , longitudenal and transverse
What is the froment paper sign?
Why is this an important test to know?
It is a way to test for an ulnar nerve palsy
The ulnar nerve innervates the adductor pollicus
Test it by asking a patient to hold a piece of paper between their thumb and their index finger. If they can not hold it OR compensate by flexing the IP) it is positive
(remember flexor pollicus longus is a LOAF muscle innervated by median)
It is important because ulnar nerve innervating D4 and D5 is largely responsible for grip power
What are the extensor components on the dorsal surface of the hand
On the back of the hand you have the lateral bands which go from your distal phalax down to MCP and the central slip with goes in between these from the Middle phalax to the dista phalanx
Why do we have lateral bands a a central slip?
Allows for coordinated extension of fingers for fine motor tasks
What is a bountinerre deformity?
When you have a central slip injury. When you extend dip, the lumbricals pulls causing PIP pops through the defect. The trinagular ligament that holds lateral bands tight loosens overtime allowing for lateral band volar subluxation
Why do we do modified Elison test? (modified is two hands)
To look for a central slip rupture BEFORE the boutinerre deformity is apparant
Have the patient flex the PIP at 90 degrees over the edge of a table. If they can extend the PIP, central slip is fine
If they cant extend the PIP but the DIP extends, the lateral bands are compensating and the central slip is broken
Important pearl for extension joint injuries?
Only joint that is affected should be splinted, others should be free
What are the boarders of the anatomical snuffbox?
Abductor pollicus longus
EPB
EPL
Bervis sandwhich
What is special about the FDP?
Flexes the DIP
D2 and D3 are median (AIN specifically)
D4 and D5 are ulnar
Why AIN is a branch of the median nerve/ why the okay sign tests the median nerve
What is the PIN then?
Branch of the radial nerve that supplies the APL and EPB in the anatomical snuffbox
What nerves supply the intrinsic muscles of the hand? what are the exception?
Ulnar, except for LOAF
What are the two types of muscles that affect the hand?
Intrinsic - origins within the hand
Extrinsic - origins proximal to the hand (forearm) and just insert in the hand
What are two compartments in forearm?
Flexors and pronators - volar
Extensors and supinators - dorsal
Why do you get flexor tenosynovitis but not extensor? What other system is unique to the flexor side of the hand?
Flexors tendons have a synovial sheath that is avascular and prone to infection
You also have a pulley system that lives over the synovial part and prevents bowstringing of tendons forward
Which pulleys are the most important?
A2 (over proximal phalanx) and A4 (over middle phalanx)
Four is farther away
How do you test FDP and FDS?
FDS - flex your PIP
FDP - flex your DIP
(everything else should be held in extension)
Outline the blood supply to the hand
radial side comes in through anatomic snuffbox goes into deep and supeficial arch
Deep arch loops around the back, superficial stays on top and supplies palmar digital arteries
Where is the neurovascular bundle in the fingers?
Edge of flexor crease making its way up the finger
What is normal two point discrimination in finger tips?
5mm
Reasons to cut a ring off?
deep erosion, open wound, neurovascularly not intact
What are three types of distal phalanx fractures? Which get antibiotics and which do not?
Tuft - crush injury, stable because held by nail and pulp. No Abx
Shaft - longitudenal (not stable) or transverse (stable)
Seymour - peds salter 1 or 2 across growth plate, usually crush and open because of nail bed injuries. Get antibiotics, if you repair plastic 1 week if not 1 day
What are 2 types of intra-articular distal phalanx fractures?
Dorsal - mallet injury, cant extend
Stack splint for 6 weeks, send to plastics if this fails or more than a third of intra articular surface
Volar - Jersey, cant flex
slight flexion for 6 weeks
If cant flex at all call plastics worry about FDP
What do you do for seymour fracture? Think from bottom out
Reduce for bone, repair nail bed, put nail overtop then cover with antibiotics
What happens with middle phalanx fractures?
How do you cast them?
Depends on where the fracture is. remember that the central slip attaches at the base and the FDS attaches more distally, so depending on where the fracture is it will deform in different ways.
stable - buddy tape
Unstable - splint to wrist, really deformed call plastics
What is the eponymous name of a very unstable middle phalanx fracture?
Pilon
Which proximal phalanx fractures are unstable?
If they involve the condyle
If they are spiral, angulated
Should have surgical repair in about a week
deform so you get apex volar (central slip pulls into extension)
What are two eponymous fractures involving the metacarpals?
Boxers fracture
Reverse Bennet (intra-articular base of the 5th)
What variations of metacarpal fractures is important to know about
Multiple
High risk of shortening and instability due to loss of intermetacarpal ligament
> 5mm of shortening - get extensor lag that you cant compensate for
What is pseudoclawing?
When MTP heads just pushed down lik you are pretending to make a cat claw with your own hand, then you cant extend your PIP all the way -> hand is stuck in this claw position
What is acceptable amount of angulation for neck and shaft metacarpal fractures?
In order for D2, D3, D4, D5
Shaft - 10,10,20,30
Neck - 15,15, 35, 45
Howe do you reduce metacarpal fracture?
Jahss maneuver
Flex MCP and PIP to 90
Press down on MCP from above
Push up on proximal phalanx to push the distal fragment back into place
Mold with same downward pressure and then upward pressure under flexor crease
What are two special fractures of thumb?
Both intra-articular fractures of the thumb
Bennet - 2 part of base
Ronaldo - 3 part fracture
Both call plastics
What is the special view for thumb xrays?
Roberts
What is the V sign on a finger xray?
Dorsal widening of the joints with minimal subluxation
General reasons to page ortho after a reduction?
NICU
Neurovascular inury
Inability to reduce
Contaminated
Unstable
Chronic dislocation, big fragments of something stuck in the joint
How do you reduce a dislocated finger?
How do you cast it? What is the one exception?
Traction and counter traction
Hyperextend or hyperflexion then reverse movement
Cast MCP at 60, IP joints at 30 unless volar dislocation then IP in extension to avoid boutinerre
Which PIP dislocation do you do an Elson test for?
Volar dislocation (central slip breaks off on top corner of proximal phalanx)
What PIP dislocation do you worry about volar plate injury?
Hyperextension mechanism. Might have volar laceration over joint. Can reduce on its own but have locking with flexion.
What type of MTP dislocation do you need to be wary of? What is the risk? How do you reduce it?
Dorsal dislocation
Two types - simple (technically a subluxation) and complex (when metacarpal head goes through the volar plate and volar plate gets stuck on top and anytime you try to put the finger back the volar plate comes with it)
If dorsal dislocation no longtidudenal traction (will trap volar plate). Dorsal pressure downward to push around. If you cant plastics (might mean dorsal plate already in there). Cast at 60 degrees
Which CMC dislocation can lead to which nerve injury?
5th CMC and ulnar nerve (claw hand deformity)
What is skiiers or gamekeepers thumb? How can you test for this clinically?
Forced abduction leading to UCL injury
Clinically will have pain on the ulnar side with radial stress
If more than 30 degrees of laxity it is a complete tear (important because incomplete thumb spica for 4 weeks and complete goes to the OR)
What is a Stener lesion?
Occurs after a complete tear of UCL when adductor pollicis aponeurosis has interposition UCL and the MCP joint.
Clinically round palpable mass on ulnar side with complete tear (rare)
What are the extensor tendon zones?
Which zone is most commonly injured?
Eight
Odds are over joints
Even are over bone
start with 1 at DIP and 2 at middle phalanx
Thumb has own still starts at 1T
Most common injury is Mallet finger (zone 1)
What is swan neck deformity?
Hyperextension of PIP and flexion of DIP
See in RA and FDS laceration
Think of it like a reverse boutinerres
What is a pseduo-bountineres?
Hyperextension injury at the PIP (not bountinerre because problem is not the central slip)
What is the extensor injury for zone 5?
Boxer knuckle
Rupture of saggital band at the MCP after punching something
Can keep hand in extension, but if you go from flexion to extension it snaps back into place
Type 1 to 3 based on no instability, snapping and then complete rupture
Laceration to back of metecarpal but you can still extend you fingers, why?
Juncturae tendonae can extend though adjacent tendons
Three types of flexor tendon avulsion injuries? Which is the worse?
How do you spot these clinically?
Type 1 - complete avulsion to palm
Type 2 to PIP
Type 3 to A4 pulley
Type 1 is worst, classification essentially goes backwards from most systems. Risk is compromised vascular supply to tendon.
Does not assume natural cascade sign on testing
What are the flexor tendon injuries? Where is no mans land?
Zone 1 - jersey finger
Zone 2 - palmer crease to prox middle phalanx (no mans land - hard to repair prone to complications
3 - does well
4 carpal tunnel - damage to median nerve
5 proximal complex
What is trigger finger?
How do you manage pathalogic fractures?
Surgery
Curette out whats in there, send for biopsy (abnormal bone will never heal- need to plate it
