La 2: Metacarpus/metatarsus

Front 1

Standard views

Back 1

Lateral
DP
DMPLO
DLPMO

Front 2

Wolff's law
-
-
-
Periostitis
-
-

Back 2

Wolff's law (adaptive)
- modelling of bone according to the stresses placed on it
- coritcal modelling is an adaptive response to increased load during exercise
-cyclic loading of the MCIII/MTIII can lead to microfractures
Periostitis (pathologic)
- direct trauma
. inflammation of periosteum and/or subperiosteal hematoma
. new bone typically not deteced for 14 days
. quiescent in 6 to 12 wks
-produced in repsonse to microfractures (bucked shins)
. heat, pain, swelling, variable degrees of lameness

Front 3

Cortical stress fractures
radiographic findings:

Back 3

focal dorsal cortex thickening (along periosteum and endosteal cortex)
lucent lines (stress fractures)
reaction wll quiescent in 6 to 12 wks (can require surgical intervention)

Front 4

Back 4

lateral view, DMPLO, DLPMO

bone production and stress fracture

Front 5

Back 5

Chronic traumatic periostitis

exuberant bone production on dorsal margin

Front 6

Periostitis - "Splints"

Back 6

Secondary to damage of the interosseous ligament
usually young horses recently started in work
involved proximal 1/2 of MCIII/MTIII and II and IV (II and III in forelimb, III and IV in hindlimb)
Radiographically:

Hint 6

new bone production between splint bone and cannon bone
periosteal reaction on the splint bone
mild soft tissue swelling
- heat and pain
- can be incidental

Front 7

Back 7

Periostitis MCII

thickening, enlargement of MCII
fusing MCIII to MCII
exuberant bone production
should be similar to MCIV

Front 8

Back 8

Periostitis
fibrous tissue
focal soft tissue swelling

injury of interosseous ligament

Front 9

Fractures
MC/MT II and IV

Back 9

most common on the distal third
fractures of distal third are most common in horses >5 years of age
proximal fractures are often complicated by infection
-proximity to tarsometatarsal joint
heal with bone prodcution - laterally into suspensory ligament
may have concurrent suspensory desmitis

Front 10

Back 10

traumatic MC IV fracture
segmental
displacement of distal body

Front 11

Back 11

Chronic MT IV fracture
healing - smooth bone production, blurred indistinc margin, bridging ossesus callus
if medial, suspensory ligament problems

Front 12

Sequestrum

Back 12

radiopaque piece of bone that has lost its blood supply
MC/MTIII are prone to sequestrum formation and infection following soft tissue injury
-thick dorsal cortex
-minimal soft tissue coverage
- poor vascular blood supply
(sclerotic, necrotic, any bone, more common in long bones, little blood supply from nutrient foramen, need blood supply from soft tissue, thickened dorsal cortex)
radiographic findings:

Hint 12

sclerotic bone fragment (sequestrum)
involucrum: margin of sclerotic bone that borders the sequestrum
cloaca: opening into the involucrum
may take 7 to 14 d following injury to see
- periosteal reaction proximal and distal to sequestrum
-soft tissue swelling
associated with infection process

Front 13

Back 13

dorsal margin of cortex, MCIII
seperating from parent bone
-sequestrum

Hint 13

2 wks later
severe soft tissue, irregular
sclerotic bone, seperation from parent bone

Front 14

Back 14

Sequestrum
-focal
sclerotic bone
involucrum

Front 15

Desmitis - origin of suspensory

Back 15

suspensory ligament originates from the proximal palmar/plantar aspect of the cannon bone
tearing of attachment results in periostitis
radiographic findings:

Hint 15

increased opacity (sclerosis) on proximal aspect of MC/MT III
- crescent shaped lucency surrounded by sclerosis
avulsion fragment may be seen

Front 16

Back 16

suspensory desmitis

square shaped radiolucency, crescent shaped
fairly uncommon

Hint 16

Front 17

Back 17

angular limb deformity

valgus - laterally displaced
varus - medially displaced

Front 18

physitis

Back 18

young horsese (4-12 mos)
also 2 yr old in training
(growing, high plane of nutrition, aseptic)

disruption of endochondral ossification
variable lameness

common locations:
radiographic findings:

Hint 18

common locations:
distal radius
distal metacarpus/metatarsus

radiographic findings:
irregular and asymmetrical widening of the physis
flaring and periosteal proliferation of the metaphysis and epiphysis
soft tissue swelling
can be associated with angular limb deformity

Front 19

Back 19

normal vs physitis

medial aspect of limb, more common

not smooth margin of physis

widening irregularity, bone production and flaring
epiphysis and metaphysis

Front 20

Angular limb deformity
-
-
-

Back 20

Angular limb deformity
-congenital (in utero)
.
.
.
.
-developmental
.
.
-acquired
.
.
.

Hint 20

Angular limb deformity
-congenital (in utero)
. positioning
. exposure to toxin or infection
. nutrition
. skeletal maturity
-developmental
.developmental orthopedic disease
. nutrition, exercise, overloading, trauma
-acquired
. trauma
. fracture
. infection

Front 21

angular limb deformity:
level of maximum deviation

Back 21

-diaphysis
-distal radial physis
- distal radial epiphysis
- epiphyseal growth imbalance
- incomplete ossification of carpal bones
- flaccidity or damage to periarticular structures

Front 22

Back 22

angular limb deformity
-used to define level of maximum deviation
. irregular physis
. wedge shaped epiphysis
. delayed development lateral styloid process
. cuboidal bone disease

Hint 22

13 degree angle of rotation
angle of maximum deviation at distal radial epiphysis
note narrowed lateral aspect of third carpal bone

Front 23

incomplete ossification of carpal bones and tarsal bones

Back 23

seen primarly in young foals
- premature, dysmature, twin - incomplete ossficiation, not enough nutrients

radiographically:
-small rounded bones/lack normal cuboidal shape
- enlargement of carpal joint spaces
- bones lack normal angular shape
- granular appearing bones
- collaps and malformation of bones
- angular limb deformity

not formed enough to support weight of animal, stress to bones, long term djd

Front 24

Back 24

incomplete ossification of carpal/tarsal bones

- small round, not completely formed
- widening of jt space
- minimal ossification

Hint 24

Front 25

Back 25

incomplete ossification

Front 26

Back 26

Tarsal Bone Collapse

Hint 26

incomplete ossification of central and third tarsal bones secondary to skeletal immaturity

radiographically
- dorsal or lateral collapse of the central or third tarsal bones
- dorsal fragmentation
- sclerosis
- angular limb deformity (tarsus valgus)
- may develop degenerative joint disease of the distal intertarsal and tarsometatarsal joints

Front 27

Septic Arthritis

Back 27

most common in foals
- failure of passive transfer and delayed closure of gut
- pneumonia
- oomphilitis
- enteritis/colitis

in adult horses it is usually associated with direct trauma to the joint or associated with an injection

radiographic bone changes may be apparent in 7 to 10 days after the onset of clinical signs

Hint 27

radiographic findings:
soft tissue swelling
bone lysis
irregular outline to subchondral bone
periosteal bone proliferation (aggressive)

abscence of changes does not rule out septic arthritis

Classification:
P type - begins in physis, involves bone on both sides
E type - begins in epiphysis
S type - begins in synovium
T type - begins in tarsus
C type - begins in carpal bones

Front 28

Back 28

Early S-type septic arthritis

Front 29

Back 29

P type septic arthritis

Hint 29

distal third metacarpal bone physis
bone lysis, sclerosis, and periosteal bone production of the epiphysis and metaphysis
sequestrum

Front 30

Back 30

P type septic arthritis

distal radial metaphysis, physis, epiphysis

bone lysis and bone sclerosis
soft tissue swelling
subcutaneous emphysema

Front 31

Back 31

C type septic arthritis

carpal bones
soft tissue swellin
bone lysis and sclerosis

Front 32

Back 32

septic arthritis and osteomyeltitis