Lecture 18 & 19 - Common Surgical disorders of the forelimb and hindlimbs in the horse

Question 1

what are the most common causes of lameness?

Answer 1

OA and soft tissue injuries

Question 2

what is another saying for navicular syndrome

Answer 2

palmar foot pain

Question 3

what is palmar foot pain and what is its etiology

Answer 3

lameness originating from the podotrochlear apparatus of the forelimb (navicular bone, DDFT, navicular bursa digital cushion

abnormal, non-physiological biomechanical loading of structures (specifically long toe, under-run heels)

Question 4

palmar foot pain is most common in which breeds of horses

Answer 4

quarter horses, thoroughbreds and warmbloods

Question 5

what is the classical clinical signs of palmar foot pain?

Answer 5

unilateral or bilateral (bilateral is more common) forelimb lameness. it is noticed most often on hard ground or when circling on the inside limb

(going clockwise, inside foot is lame = right foot with palmar foot pain)

Question 6

what is the treatment for palmar foot pain

Answer 6

management since its a degenerative problem

gold standard: hyaluronic acid with a low dose corticosteroid

Question 7

name the 7 types of 3rd phalanx fractures:

Answer 7

Type 1 = abaxial/wing fracture non-articular - good px
type 2 = abaxial/wing fracture, articular - fair px, OA likely
type 3 = axial/saggital fracture, tx: screw fixation, guarded px unless young animal, OA develops
type 4 = extensor process fracture, form of OC?, tx: fragment removal, px: good
type 5 = comminuted fracture, poor px
type 6 & 7 = solar margin fracture good px (type 7 occurs in a foal)

Question 8

2nd phalanx fracture - which leg is most common? what breed is most common? which tx has best px?

Answer 8

hindlimb > forelimb

seen most often in quarter horses

plantar/palmar eminence fractures, plating combined with PIP arthrodesis have better px

Question 9

what are the two categories of first phalanx fracture?

Answer 9

1. OCFs of the metacarapal or metatarsal joints
   
   • common in race horses
   • due to hyperextension injury
2. diaphyseal fractures
   
   • result from torsional & axial forces - aka “screwdriver” fracture
   • most require internal fixation (lag screw repair)
   • severe diaphyseal fracture has poor px and ends w/ euthansia

Question 10

what are the two conditions we see with metacarpo/metatarso phalangeal joings (fetlock) joints?

Answer 10

1. “POD” - palmar/plantar osteochondral disease

2. condylar fractures of MC3 / MT3

Question 11

what is “POD”? what does it lead to? what does it preidspose to? which horses are most commonly affected? how is dx? how is it tx?

Answer 11

POD is a repetitive stress injury that results in maladaptive bone remodeling.
it leads to OA
it predisposes to MC3/MT3 condylar fractures
TB racehorses most affected
dx: bone scan, MRI and CT
tx: Rest! continued training worsens and may lead to catastrophic failure

Question 12

condylar fractures of MC3/MT3: common in which horse? what do the fractures typically look like?

Answer 12

common in racehorses

vertrical fracture that propagates proximally and sagitally from the joint

Question 13

**where do condylar fractures of MC3 / MT3 usually occur?
what types of fractures are they?
in which jiont do they occur **

Answer 13

lateral condyle: short and complete, more common in MC3

medial condyle: spiral, more common in MT3

Question 14

what is a bucked shin? and where does it occur? what does it predispose to?

Answer 14

a bucked shin is a lameness from dorsal cortex maladaptive remodeling of MC3 (cannon bone)

it does not occur in MT3

it predisposes to dorsal cortical fractures

Question 15

what is the most commonly incomplete “stress” fracture

Answer 15

dorsal cortical fracture of MC3 (aka cannon bone)

Question 16

if you have a horse with an INCOMPLETE dorsal condylar fracture, what is your tx?

Answer 16

JUST osteostixis

Question 17

what is osteostixis?

Answer 17

if you just have a stress fracture you take a small drill bit and make holes thru the cortex and it allows bone marrow and blood to heal the fracture

Question 18

splint bone fractures - MC2&4 and MT2&4 etiology

Answer 18

direct trauma and exercise

they are held onto the cannon bone by the intraosseus ligament –> over exercise and stress causes a desmitis and they can pop a splint

Question 19

what is the tx of splint bone 2& 4 fractures

Answer 19

closed fractures - rest. healing can result in a large exostosis (callus) bc these bones have a “weird” periosteum which can impinge on the suspensory ligament.

removal (partial splint ostectomy) - generally up to 2/3 of the distal aspect of either MC/MT2 or MC/MT4 without risk of destabilization of the carpus or tarsus.

Question 20

osteochondral fragmentation (aka chip fractures) where are they most common and incorporating which bones?

Answer 20

more common on the medial side

incorporating:

1. distomedial radius
2. proximal/distal RCB (on exam) and ICB
3. proximal 3rd CB

Question 21

what is the most common site of a fracture in the carpus?

Answer 21

a slab fracture of the radial facet of carpal bone 3.

Question 22

where are bi-articular fractures most commonly seen in the carpus?

Answer 22

frontal plane, rarely the sagittal plane

Question 23

which joints in the tarsus communicate?

Answer 23

the tibiotarsal joint and proximal intertarsal joints communicate (top two)

the distal intertarsal joint and tarsometatarsal joints communicate (bottom two)

Question 24

which joints communicate in the carpus?

Answer 24

the radiocarpal joint has no communication

the middle and carpometacarpal joints communicate

Question 25

what is the most common disorder of the tarsus (aka hock)

Answer 25

OA

Question 26

where does OA typically occur in the tarsus and what is it called?

where does the bone proliferation typically occur?

Answer 26

most commonly in the distal intertarsal jiont and tarsometatarsal joint - its called “bone spavin”

medial bone proliferation

Question 27

what is one of the treatments for OA in the tarsus and what must you confirm before doing this tx?

Answer 27

chemical facilitated ankylosis: you put 70% ethyl alcohol in the tarsometatarsal joint and distal intertarsal joint. BUT you first must confirm that the distal intertarsal joint and proximal intertarsal joint do not communicate.

Question 28

if you confirm that your tarsometatarsal joint and distal intertarsal joint communicate, how do you treat?

Answer 28

ethyl alcohol - no big deal: those joints are supposed to communicate.

Question 29

when is PSD (proximal suspensory desmitis) of the forelimb worse?

Answer 29

lameness worse on soft ground, limb on outside of circle

Question 30

what nerves do you try to localize in PSD of the forelimb?

Answer 30

deep br. lateral palmar n.
lateral palmar n.
med and lat. metacarpal nn.
direct infiltration

Question 31

how do you treat PSD (proximal suspensory desmitis) of the forelimb?

Answer 31

REST AND ICE!!

sometimes surgery: fasciotomy and neurectomy

Question 32

PSD of the hindlimb is common in which type of athletic horse?

Answer 32

english sport horses

Question 33

PSD of the hindlimb is worse when _______

Answer 33

lameness worse on SOFT ground, limb on outside of a circle

Question 34

localization of PSD in the hindlimb is more challenging in which nerves?

Answer 34

deep b. lateral plantar n.
med and lateral metatarsal nn.
direct infiltration
distal hock joints/low 4-point

Question 35

how do you diagnose PSD of hte hindlimb?

Answer 35

US - challenging
radiographs
MRI - gold standard

Question 36

what is the tx of PSD in the hindlimb?

Answer 36

• REST AND ICE!
• foot balance shoeing
• surgery

Question 37

what is the surgical procedure for tx PSD of the hindlimb?

Answer 37

you cut the retinaculum and the nerve to release the compression around the proximal aspect of the suspensory ligament via a fasciotomy +/- neurectomy

Question 38

what improves the prognosis of PSD in the hindlimb?

Answer 38

fasciotomy +/- neurectomy aka surgery!

Question 39

what is a tx option for superifical digital flexor tendonitis? what does it increase the risk for?

Answer 39

superior check desmotomy

it increases the risk of suspensory ligament injury

Question 40

what does superior check desmotomy predispose the horse to?

Answer 40

suspensory ligament desmitis

Question 41

is the forelimb or hindlimb more commonly affected by lameness? and which part of this limb is most effected?

Answer 41

80% forelimb

95% originates distal to carpus