56. Carpus Flashcards
3 bones in the proximal row
- radial carpal–medial2. ulnar carpal–lateral3. accessory–caudaldistal row of carpus = 1-4 carpal bones
classification type of carpal joint
ginglymus (hinge)
describe the epiphysis of the metacarpal bones
MC I has epiphysis at proximal endMC II-V have a single epiphysis at the distal endossification complete 5-6 months
list two anatomical differences in the dog vs the cat distal forelimb/carpus
- 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
mean peak ground reaction force on the forelimbs as a percentage of body weight
108% of body weight
radiographic views for diagnosing carpal abnormalities
survey filmsstressed filmsobliqued filmsskyline views
traumatic radial carpal bone fractures
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,
accessory carpal bone fracture classfication
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
surgical guidelines for MC and MT fractures
- > 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
MC fractures seen in greyhounds
2 and 5 of the right thoracic limb
methods of repair for MC/MT fractures
–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
sesamoid disease
racing greyhounds and rottweilerssesamoids 2, 7have fewer vascular foraminado better treated conservatively 4-8 weeks splint or bandage
overall, list carpal injuries that greyhounds are at risk of
radial carpal traumatic fractures –RIGHTaccessory carpal bone fractures–RIGHT type 1 MC fractures 2 right 5 leftsesamoid bone fracture 2 and 7
most common injury to the canine carpus
hyperextension injurydamage to flexor retinaculum and palmar fibrocartilagecan result in luxation31% antebrachiocarpal joint22% intercarpal joint47% carpametacarpal joint ****tx: pancarpal or partial carpal arthrodesis
tendon affected when digits are “elevated” during normal weight bearing
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
T/Fif a antebrachiocarpal joint injury is present, a pan carpal arthrodesis is indicated
true
ideal angle for pan carpal arthrodesis
10-12 degrees of extensionpalmar surface is the tension surface (difficult, more dissection)plates can be applied (medial, palmar, dorsal)
principles of arthrodesis
- remove articular cartilage2. normal standing angle 3. graft to promote healing/union4. rigid stabilization of fixation5. immobilization post op
types of fixation for carpal arthrodesis
- DCP2. Hybrid DCP3. Castless plate4. Single or double step hybrid arthrodesis plate5. linear ESF6. circular ESF
complications associated with pan carpal arthrodesis
complications can be as high as 50%–screw loosening (fail at distal screw)–implant breakage/failure–delayed healing–infection–MC fracture
recommendations for plate fixation of carpal arthrodesis
screws should not be more than 40% of the MC diameterplate should span > 50% length of MC III
comparison of 3.5 DCP vs 2.7/3.5 hybrid DCP for arthrodesis
favored hybrid arthrodesis plate which did not fail at the distal screw hole
partial carpal arthrodesis fixation techniques
- plates—T plates2. cross pins3. pins from MC bones thru carpometacarpal and middle carpal joints
carpal laxity syndrome
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
digital neoplasia
digit masses usually neoplastic–61% malignantsubungal BAD38% SCC32% melanoma
Paw pad corns
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
