Equine Appendicular Skeleton

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Equine ppendicular Skeleton Tony Pease, DVM, MS, DCV ssistant Professor of adiology North Carolina State University bjectives cquisition of radiographs

1 Equine ppendicular Skeleton Tony Pease, DVM, MS, DCV ssistant Professor of adiology North Carolina State University bjectives cquisition of radiographs adiographic anatomy adiographic patterns of disease Determine normal compared to abnormal How ultrasound is helpful Pages Pages eading 1

2 It starts with the view Need to know anatomy Naming views Based on how image acquired Marker is always dorsal or lateral Hang films with dorsal or cranial to the left ateral is not as rigid Cranial Caudal Cranial Caudal Dorsal Palmar Dorsal Plantar 2

3 We Will Cover Carpus Tarsus Metacarpo(tarso)phalangeal Digit Carpus Views Dorsopalmar ateromedial Flexed lateromedial Dorsolateral-palmaromedial Dorsomedial-palmarolateral Dorsoproximal-dorsodistal skyline Distal radius Proximal row Distal row DP M FM D DM DP View Marker is TE ccessory carpal bone The accessory carpal bone is a good landmark; it is lateral ateral Medial 3

Should be at TE aspect of limb (palmar) 60º off dorsal 30º off lateral D S M E D I C4 MCIV P M T E

4 ateral View Marker is DS Carpal Fat Pad Flexed ateral Marker is DS Intermediate carpal bone is more proximal than radial carpal bone Intermediate carpal bone adial carpal bone D ccessory Marker INCECT Should be at TE aspect of limb (palmar) 60º off dorsal 30º off lateral D S M E D I C4 MCIV P M T E Fourth carpal bone and MC IV have a malaligned appearance ccessory carpal bone is NT superimposed with the carpus 4

5 DM 60º off dorsal 30º off medial Marker is TE D S T E C2 MCII ccessory P M M E D I Second carpal bone and MC II line up evenly accessory carpal bone is superimposed with the carpus Note mal alignment of C4 and MC4 in D D DM Note alignment of C2 and MC2. lso note C1 and indentations in C2 and MC2; don t confuse with lesions. C1 is not always present; sometimes it is larger than shown here. C1 C5 5

6 Dorsoproximal dorsodistal view of carpus Proximal row of carpal bones Distal row of carpal bones Distal radius M of distal radius CT of distal radius Distal adius ateral Digital Extensor Common Digital Extensor Extensor Carpi adialis CT of distal radius 6

Proximal Carpal ow U I Distal Carpal ow 2 4 3 Tarsus Dorsoplantar DP ateromedial M

7 Proximal Carpal ow U I Distal Carpal ow Tarsus Dorsoplantar DP ateromedial M Dorsolateral-plantaromedial D Dorsomedial-plantarolateral DM Plantaroproximal-Plantarodistal Skyline 7

8 Dorsoplantar Calcaneus Marker is TE ateral Medial ateral Calcaneus Marker is DS D 60º off dorsal 30º off lateral Marker is TE D S M E D I Calcaneus T4 MC4 T4 and MC4 are malaligned Calcaneus not superimposed with the tarsus Medial trochlea does not have a distal hook 8

the deep digital flexor tendon Sustentaculum tali Metacarpo(tarso)phalangeal joint Dorsopalmar

9 DM 60º off dorsal 30º off medial Marker is TE D S T E T2 and MT2 line up Calcaneus superimposed on tarsus arge hook distal aspect of lateral trochlea (arrow) P N T M E D I Calcaneus Skyline rea of the deep digital flexor tendon Sustentaculum tali Metacarpo(tarso)phalangeal joint Dorsopalmar ateromedial Dorsolateral-plantaromedial Dorsomedial-plantarolateral Flexed ateromedial DP M D DM FM 9

10 DP Marker is TE M Marker is DS D 35º from dorsal 55º from lateral D S Marker INCECT Should be at TE aspect of limb M E D I P M T E 10

medial and lateral condyles Distal Phalanx and Navicular Bone 0 Dorsopalmar Dorsal 60

11 DM Marker is TE 35º from dorsal 55º from medial D S T E P M M E D I FM Marker is DS Sagittal ridge The sagittal ridge is less opaque and more dorsally located than the medial and lateral condyles Distal Phalanx and Navicular Bone 0 Dorsopalmar Dorsal 60 proximal-palmarodistal ight and dark ateromedial Palmaroproximal-palmarodistal 0 DP 60 DP M Skyline 11

12 Foot Must Be Prepared 12

$distal phalanx fractures and$

13 0 DP Good to assess joint width, collateral cartilages and periphery of navicular bone 60 DP Projects navicular bone on middle phalanx, not superimposed on joint Primary use is for navicular bone changes Good for distal phalanx fractures and margin evaluation 13

$Carpus Chip fractures Primarily in$

14 M Good for rotation of distal phalanx, remodeling of navicular bone and DJD Navicular Skyline Flexor eminence Palmar process of P3 Carpus Chip fractures Primarily in racing animals Degenerative joint disease Very common 14

$Types of fracture$ involving one

15 Types of fracture Chip Small fragment involving one articular surface Corner Moderate sized fragment that involves one articular surface (larger than a chip) Slab Involving two articular surfaces 15

$? Which bone is fractured?$ Tarsus Degenerative joint disease Distal intermediate ridge fragments steochondrosis/osteochondritis

16 ? Which bone is fractured? Flexed view aids in localizing fracture to Intermediate carpal bone emember I is HIGH! Tarsus Degenerative joint disease Distal intermediate ridge fragments steochondrosis/osteochondritis dessicans Tarsal DJD adiographic changes Poor correlation with clinical signs Most horses will have or soon develop some evidence of tarsal degenerative joint disease Not always clinically important 16

17 steochondritis dessicans Three main spots in tarsus Distal Intermediate idge of the Tibia (DIT) ateral Trochlear idge Medial Epicondyle 17

Intermediate idge of the Tibia Trochlear steochondrosis

18 D.I..T. Distal Intermediate idge of the Tibia Has been called osteochondrosis r osteochondritis dessicans (CD) Not always associated with clinical signs Normal Distal Intermediate idge of the Tibia Trochlear steochondrosis ffects lateral ridge more commonly May see in young horses or in older horses flattening may be persistent from prior D. 18

ateral Trochlear idge Medial Malleolus Digit aminitis otational Sinking Navicular syndrome Fractures Collateral cartilage mineralization Sole abscess

19 ateral Trochlear idge Medial Malleolus Digit aminitis otational Sinking Navicular syndrome Fractures Collateral cartilage mineralization Sole abscess aminitis otational ssess position of distal phalanx relative to the dorsal hoof wall Sinking ssess position of distal phalanx relative to coronary band 19

$angle Gas in hoof wall emodeling of tip of distal phalanx May progress to Type VI fracture Gas due to separation of lamina ines are same length vergrown toe can$

20 otational laminitis Palmar rotation of distal phalanx Measurement vs. subjective vs. angle Gas in hoof wall emodeling of tip of distal phalanx May progress to Type VI fracture Gas due to separation of lamina ines are same length vergrown toe can exaggerate appearance of rotation otation commonly results in remodeling 20

$Can measure angle Coin used to mark coronary band and dorsal hoof wall otation has resulted in fracture Sinking aminitis Distal$

21 Can measure angle Coin used to mark coronary band and dorsal hoof wall otation has resulted in fracture Sinking aminitis Distal phalanx may be parallel to hoof wall Distal phalanx is displaced distally in hoof Sinking line Increased hoof wall thickness 21

ug 14 ug 25 Note increased hoof wall thickness and

coronary band to the extensor process to be < 1 cm.

disease Poor correlation between radiographic

enthesophytes Enlarged synovial invaginations

22 ug 14 ug 25 Note increased hoof wall thickness and sinking line Generally, the distance from the coronary band to the extensor process to be < 1 cm. Navicular Syndrome Initially is likely a soft tissue disease Poor correlation between radiographic changes and soundness Common findings Peripheral enthesophytes Enlarged synovial invaginations Medullary sclerosis/cyst-like lesions steophytes Peripheral enthesophyte 22

23 Synovial invaginations Extensive enthesophytosis, synovial invaginations, flexor cortex erosion Erosion of the flexor surface Indicates adhesions to the deep-digitalflexor tendon Most reliable sign of navicular disease 23

$Distal phalanx fractures eview types; page 278 in text? T? ook for lines that do not follow vessel? pattern Need lighter exposure for toe?$

24 Distal phalanx fractures eview types; page 278 in text? T? ook for lines that do not follow vessel? pattern Need lighter exposure for toe? region Foot must be prepared properly with packing Still unsure take oblique radiographs MED Dorsal 45 proximal 45 lateral - Palmarodistomedial (DP) Will project lateral wing 24

$misdiagnosis of fracture Not a fracture TE EFT FT IGHT FT$

25 DP DPM Collateral Cartilage Mineralization Common in draft horses Can occur in any horse May not result in lameness May be asymmetric May arise from multiple sites leading to misdiagnosis of fracture Not a fracture TE EFT FT IGHT FT MEDI 25

to osteomyelitis Distal phalanx has limited proliferative capacity

26 In lateral view, collateral cartilage mineralization creates heterogeneous opacity caudal to navicular bone Sole bscess May lead to osteomyelitis Distal phalanx has limited proliferative capacity Most abscesses are lytic Don t confuse crena with abscess 5/27 6/17 7/15 26

27 Sequestrum Devitalized bone fragment Some believe needs to be infected thers feel you can be sterile Common in MT3 and MC3 Poor communication between endosteal and periosteal blood supply Fragment surrounded by lucent region Sequestrum is not more opaque 27

28 Involucrum the black halo of necrotic tissue surrounding the sequestra Sequestra the devitalized fragment of bone Cloaca Draining tract from sequesta Equine M The New Frontier Why Equine MI? Significant lameness results from soft tissue injury Not visible in radiographs Superior contrast resolution of M is beneficial 28

29 Closed/ Short bore Magnet at WSU Standing Magnet pen Magnet 29

30 NC

31 31

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