wrist trauma. fractures and dislocations of the wrist clinically point tenderness over the wrist...
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Wrist Trauma
Fractures and Dislocations of the Wrist
• Clinically point tenderness over the wrist with >20% loss of grip strength are good physical indicators
• Complex anatomy requires four views for interpretation
• Neutral PA, PA in ulnar deviation, medial oblique and lateral
• Advanced imaging very useful because fractures not always visible
Normal Anatomy
http://uwmsk.org/RadAnat/WristPALabelled.html
Distal Radius Fractures• Fractures may be subtle or even occult• Alteration of pronator quadratus fat plane is a useful
indicator of fracture• Distal radial fractures
include:
-Colles’, Smith’s, Barton’s,
Chauffer’s, Moore’s,
torus, slipped radial
epiphysis
http://radiology.rsna.org/content/244/3/927.full
• Colles’ fracture- fx. of distal radius with posterior angulation of distal fragment– Usually FOOSH– Osteoporosis is risk factor, so increased incidence in
women>65
• Smith's fracture (reverse Colles’ fracture)- fracture of distal radius with anterior angulation of distal fragment
– Less common than Colles’– Direct blow or fall on flexed hand
Distal Radius Fractures
http://imageinterpretation.co.uk/wrist.html
Distal Radius Fractures• Barton’s fracture (rim fx.)- posterior rim fracture of
distal radial articular surface with associated proximal dislocation of carpals– Will see overlap of proximal row with articular surface of
radius
• Chauffeur’s fracture (backfire fx., Hutchinson's fx.)- fracture of radial styloid– Caused by avulsion or impaction by scaphoid– Formerly caused by starting cars with hand cranks
http://www.radiologyassistant.nl/en/476a23436683bhttp://radiographics.rsna.org/content/24/4/1009/F11.expansion.html
Distal Radius Fractures• Moore’s fracture- fracture of ulnar styloid
process and dislocation of distal ulna associated with Colles’ fracture
• Torus fracture- buckling of cortex after trauma– Happens in children– Can happen in any long bone– Radiographic sign is bump or bulge of cortex
Distal Radius Fractures
• Slipped radial epiphysis- childhood equivalent of Colles’ fracture– Hyperextension injury (FOOSH) causes shearing of
radial epiphysis, which gets displaced posteriorly– Usually has small metaphyseal fragment (corner
sign), which makes it Salter-Harris II
http://www.oha.or.kr/skr/trauma/trauma4.htm
Distal Unlar Fractures
• Ulnar styloid process fracture- rare as an isolated fracture– Usually avulsion by ulnar collateral ligament– More frequently found as associate fracture with
other injuries
• Distal ulnar shaft fracture- see “nightstick fracture” from forearm fracture section
Scaphoid Fractures• Most common carpal bone to fracture
– Usually ages 15 to 40; rare in children
• FOOSH• Clinical presentation is snuffbox pain with
swelling• Most common site for occult fracture• Classified by anatomic location of fracture line
– Waist (70%), proximal pole (20%) and distal pole (10%)
Scaphoid Fractures
• Initially radiographs may be negative• Repeat x-ray in 10 to 20 days or advanced
imaging immediately– MRI makes most sense if US not available
• Complications include:– AVN, nonunion, carpal instability and radiocarpal
degenerative arthritis
Scaphoid AVN• Scaphoid had 2 blood supplies
– Proximal pole is supplied by an artery that enters distally
• The more proximal the fracture is, the more likely AVN will occur if untreated
• Radiographic signs include increased density (dead bone) and fragmentation
Nonunion
• Missed diagnosis may lead to delay in treatment• Over time fracture line will widen and margins
will become smooth and sclerotic
Carpal Instability
• Follows rupture of scapholunate ligament• Radiographic features include:
– Terry Thomas sign- widening of scapholunate jt. space >4 mm
– Ring sign- rotation of scaphoid – Loss of parallel joint surfaces
Radiocarpal Degenerative Arthritis• Radiographic signs are that of OA anywhere
else in the body• OA signs at the radiocarpal joint in the absence
of trauma suggests diagnosis of CPPD• SLAC (ScaphoLunate Advanced Collapse) wrist
may follow if capitate is allowed to migrate proximally
Triquetral Fractures• 2nd m.c. carpal bone to fracture• Usually by avulsion from dorsal surface by
radiocarpal ligament (Fisher fracture)– Small flake dorsally only identifiable on lateral film
Fractures of Other Carpal Bones• All may fracture, but unusual unless
directly traumatized• Hamate frequently complicated by non-
union• Lunate frequentlyly complicated by avascular necrosis (Keinböck’s disease)
http://orthoinfo.aaos.org/topic.cfm?topic=a00017
Dislocations of the Wrist• Two patterns
– 1. a single bone that dislocates relative to remaining carpals
– 2. a single bone that remains in place with the surrounding carpals dislocating
• Evaluation of carpal arcs is a useful tool– Arc 1- proximal articular surfaces of proximal row– Arc 2- distal articular surfaces of proximal row– Arc 3- proximal surfaces of distal carpals (capitate and hamate)– Disruption indicates dislocation
http://www.radiologyassistant.nl/en/42a29ec06b9e8
Single Carpal Dislocations• Lunate dislocation- most common carpal bone to
dislocate– On PA film dislocated lunate appears triangular (pie sign)– Rows 2 and three disrupted
• Scaphoid dislocation- – On PA film, see ring sign and Terry Thomas sign as
previously described
• Other single carpal dislocations unusual and require severe trauma
Multiple carpal dislocations• Perilunate dislocation- dorsal displacement of all carpals
except lunate, which stays in place– On lateral, capitate does not sit in the lunate– On PA, capitate overlies lunate
• Trans-scaphoid perilunate dislocation- same as above, but with associated scaphoid fracture
• de Quervaine’s fracture dislocation- anterior dislocation of lunate as well as proximal fragment of fractured scaphoid
http://www.imageinterpretation.co.uk/wrist.html
Fractures of 2nd - 5th Metacarpals
• Boxers fracture- transverse fracture of neck of second or third metacarpals– Result of straight jab with fist
• Barroom fracture- transverse fracture of neck of fourth or fifth metacarpals– Result of roundhouse blow from inexperienced
fighter
First Metatarsal Fractures• Bennett's fracture- intra-articular fracture through
base of the first metacarpal with dorsal displacement of the shaft– A small medial fragment remains at its articulation with
trapezium
• Rolando's fracture (comminuted Bennet’s) same as above but comminuted
• Transverse fracture- most common fracture of first metacarpal– Doesn't interfere with articulation
• Distal phalangeal fractures– Described as transverse, longitudinal, comminuted or chip fractures– Chip fractures occur at posterior or anterior corners of phalangeal base
• Posterior chip fracture inactivates extension of the DIP joint and produces flexion deformity (mallet or baseball finger)
• Middle phalangeal fractures– Chip fracture at anterior aspect of base (Volar plate fracture)
References
• Yochum, T.R. (2005) Yochum and Rowe’s Essentials of Skeletal Radiology, Third Edition. Lippincott, Williams and Wilkins: Baltimore.