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.