56. Carpus

Question 1

3 bones in the proximal row

Answer 1

1. radial carpal–medial2. ulnar carpal–lateral3. accessory–caudaldistal row of carpus = 1-4 carpal bones

Question 2

classification type of carpal joint

Answer 2

ginglymus (hinge)

Question 3

describe the epiphysis of the metacarpal bones

Answer 3

MC I has epiphysis at proximal endMC II-V have a single epiphysis at the distal endossification complete 5-6 months

Question 4

list two anatomical differences in the dog vs the cat distal forelimb/carpus

Answer 4

1. absent straight portion of the MCL of the carpus in a cat (dogs have both straight and oblique parts of the MCL)2. cats have 2 dorsal elastic ligaments that attach to the medial and dorsal aspect of the ungual crest to allow the claw to be retractable

Question 5

mean peak ground reaction force on the forelimbs as a percentage of body weight

Answer 5

108% of body weight

Question 6

radiographic views for diagnosing carpal abnormalities

Answer 6

survey filmsstressed filmsobliqued filmsskyline views

Question 7

traumatic radial carpal bone fractures

Answer 7

male ESS, Boxer, Pointer Setter–nontraumatic suspect incomplete ossificationGrey hounds–traumatic; RIGHT radial carpal bone; oblique mid body fracturetx: excised if small, lag screw or K wire; coaptation if non displaced,

Question 8

accessory carpal bone fracture classfication

Answer 8

greyhounds right carpus bc run counterclockwise1. articular distal 67% most common2. articular proximal3. nonarticular distal (origin of accessory metacarpal log that attach to MC 4, 5)4. nonarticular proximal (flexor carpi ulnaris m attach)5. comminuted

Question 9

surgical guidelines for MC and MT fractures

Answer 9

1. > 2 MC/MT fractured in the same manus2. if fractures involve primary weight bearing (3, 4)3. articular fx4. fragments displaced >50%5. fx involving base of MC/MT 2, 56. large-giant breed or working dog

Question 10

MC fractures seen in greyhounds

Answer 10

2 and 5 of the right thoracic limb

Question 11

methods of repair for MC/MT fractures

Answer 11

–external coaptation regardless of surgical technique–small bone plates (lateral/medial vs cranially)–normograde (dorsally) pin placement–Dowel pinning technique–ESF with pins and epoxy–digit amputation

Question 12

sesamoid disease

Answer 12

racing greyhounds and rottweilerssesamoids 2, 7have fewer vascular foraminado better treated conservatively 4-8 weeks splint or bandage

Question 13

overall, list carpal injuries that greyhounds are at risk of

Answer 13

radial carpal traumatic fractures –RIGHTaccessory carpal bone fractures–RIGHT type 1 MC fractures 2 right 5 leftsesamoid bone fracture 2 and 7

Question 14

most common injury to the canine carpus

Answer 14

hyperextension injurydamage to flexor retinaculum and palmar fibrocartilagecan result in luxation31% antebrachiocarpal joint22% intercarpal joint47% carpametacarpal joint ****tx: pancarpal or partial carpal arthrodesis

Question 15

tendon affected when digits are “elevated” during normal weight bearing

Answer 15

flexor tendon injury–DDFT (positioned palmar to SDFT at the level of the metacarpophalangeal joint distally)keep tension off digits–keep in flexortendon suturing techniques–may not be an option for delayed and/or chronic repair

Question 16

T/Fif a antebrachiocarpal joint injury is present, a pan carpal arthrodesis is indicated

Answer 16

true

Question 17

ideal angle for pan carpal arthrodesis

Answer 17

10-12 degrees of extensionpalmar surface is the tension surface (difficult, more dissection)plates can be applied (medial, palmar, dorsal)

Question 18

principles of arthrodesis

Answer 18

1. remove articular cartilage2. normal standing angle 3. graft to promote healing/union4. rigid stabilization of fixation5. immobilization post op

Question 19

types of fixation for carpal arthrodesis

Answer 19

1. DCP2. Hybrid DCP3. Castless plate4. Single or double step hybrid arthrodesis plate5. linear ESF6. circular ESF

Question 20

complications associated with pan carpal arthrodesis

Answer 20

complications can be as high as 50%–screw loosening (fail at distal screw)–implant breakage/failure–delayed healing–infection–MC fracture

Question 21

recommendations for plate fixation of carpal arthrodesis

Answer 21

screws should not be more than 40% of the MC diameterplate should span > 50% length of MC III

Question 22

comparison of 3.5 DCP vs 2.7/3.5 hybrid DCP for arthrodesis

Answer 22

favored hybrid arthrodesis plate which did not fail at the distal screw hole

Question 23

partial carpal arthrodesis fixation techniques

Answer 23

1. plates—T plates2. cross pins3. pins from MC bones thru carpometacarpal and middle carpal joints

Question 24

carpal laxity syndrome

Answer 24

synonymous with carpal flexure deformity in puppiesDobies, Shar Peisdiet NOT an issueConcrete floors with little room to exercise = RISK recovery 1-4 weeks no evidence that says support is needed

Question 25

digital neoplasia

Answer 25

digit masses usually neoplastic–61% malignantsubungal BAD38% SCC32% melanoma

Question 26

Paw pad corns

Answer 26

GREYHOUNDhyperkeratotic condition, lame and painful90% 3,4 digits of the thoracic limbscan surgically excise but recurrence > 50% within 2 monthsfun fact: dogs other than grey hounds do not get recurrence