Lecture 17 - Developmental Orthopedic Diseases in Horses Flashcards
disturbances in endochondral ossification like retention of cartilage and necrosis leads to _________?
subchondral bone cysts
what do longstanding lesions progress toward and what are its effects?
longstanding lesions progress to OA, causing lameness and permanent joint damage.
once this happens, you can’t change anything. this is why its best to treat OA earlier rather than later.
what are the most common sites of OC in the horse?
- tarsus (hock) - distal intermediate ridge of tibia
- stifle - femoropatellar joint - LTRF
- stifle - medialfemorotibial joint - MFC
- fetlock - metacarpo/metatarsophalangeal joint
what are the most common breeds to get OC?
- thoroughbreds
- quarter horses
- standardbreds
- warmbloods
what is the tx of choice for OC in horses?
arthroscopy - both diagnostic and therapeutic!
removing OC fragments is impt
what is the main difference between subchondral bone cysts and OCD?
horses with subchodnral bone cysts often occur LAME, unlike OCD horses. This is bc subchondral bone cysts almost always exist on the weightbearing surface of the bone or joint.
what is the most common site for a subchondral bone cyst?
medial femoral condyle
also navicular bone and phalanges
define varus and valgus angular limb deformities
valgus = external rotation varus = internal rotation
describe perinatal category of angular limb deformity
late gestation or early in life:
incomplete ossification of the cuboidal bones = in carpus and tarsus
- usually develop valgus deformity due to limited weight bearing capacity
periarticular laxity = weak muscles, tendons and ligaments
- may oscillate between varus and valgus
- manual straightening is possible
what are the two categories of angular limb deformities
perinatal factors and developmental factors
what is the main difference btwn perinatal factors and developmental factors
perinatal factors occur in late gestation or early in life: manual straightening possible
developmental factors occur during growth (true DOD): manual straightening NOT possible
what are the two possible causes of developmental factors leading to angular limb deformities in the horse?
- unbalanced nutrition - leads to abnormal growth at the level of hte physis. (joints normal)
- excessive exercise or trauma - microfractures at the physis proliferative zone, physeal crush injuries (SH type 5)
what is the treatment for angular limb deformities (there are 4)
- stall rest
- hoof manipulation: changing the ground reaction on the limb
- surgical:periosteal transection and elevation
- surgical: growth retardation
what hoof manipulation techniques are available for valgus angulation?
trim the OUTSIDE of the hooves
or apply extensions to the inside of the hoof
what hoof manipulation options are available for a horse with varus manipulation?
trim the inside of the hoof
or
apply hoof extensions to the outside of the hoof
what requirement must a horse with an angular limb deformity have in order to be be considered for a periosteal transection and elevation?
their physis must still be active!
what is one advantage of doing a periosteal transection and elevation to correct an angular limb deformity?
you cannot over correct!
when do you perform a periosteal transection and elevation in order to correct an angular limb deformity? why is this procedure done?
perform during rapid growth on concave (short) side - lateral if a valgus deformity
it accelerates growth of the short side
what is juvenile arthritis
sequelae to incomplete ossification of cuboidal bones
where is juvenile arthritis most common?
the tarsus aka hock
what is a flexural deformity
deviation of the limb in the saggital plane
what types of flexural deformities are there?
hyperflexion and hyperextension (can be congenital or acquired)
congenital contracture deformities - what sites are most common, how is treated?
is manual straightening possible?
carpus and fetlock contracture most common
best tx: oxytetratcycline if in 1st week of age
manua straightening is NOT possible
congenital hyperextension deformity - common in what type of foals? what is it secondary to? what tx is available?
dysmature foals
secondary to flexor muscle flaccidity
tx: dynasplints!
what is acquired contracture flexural deformity and what two types are there?
its when lone bone growth occurs faster than flexor tendon growth
two types:
DIPJ contracture = club foot (distal interphalangeal joint)
MCP / MTPJ contracture = knuckling fetlock (metacarpal phalangeal joint)
where is DIPJ contracture most common and how is it classified?
most common in the forelimb
classified by severity:
stage 1 - club foot LESS than 90 degrees - cut the inferior check and/or DDF
stage 2 - club foot GREATER > 90 degrees - cut inferior check ligament or DDF
what is MCP / MTPJ contracture, what is it is prognosis?
its upright angle or knuckling of fetlock
it has a worse px than DIPJ contracture (club foot)
tx is the same as club foot: cutting the check ligament or DDF, reduction in calories, NSAIDs, controlled exercise, toe extension, dynasplint
what disorders are considered true DOD?
- developmental factors of angular limb deformities
- acquired contracture - like DIPJ contracture and MTPJ contracture
- physitis
what is physitis and where does it commonly occur?
enlargement of one or more physes due to disruption of normal endochondral ossification
occurs most commonly: radius, tibia, cannon
disturbances in endochondral ossification like splitting of cartilage results in _______?
OCD lesions
