Angular and Flexural limb deformities Flashcards
What are the 3 types of foal growth abnormalities?
Angular limb deformities, tendon and ligament laxity, flexural deformities (contracted tendons)
What is the definition of ALD?
Medial or lateral deviation to the long axis of the bone in the frontal plane
What is lateral deviation distal to the point of deviation called
VaLgus
What is medial deviation distal to the point of deviation called?
varus
What usually accompanies an ALD in foals?
Rotational deformity (outward or inward rotation)
-can grow out of these
-usually due to chest being so wide compared to limbs
What is the typical signalment for ALDs?
Usually young foals (rapidly growing), all breeds affected, slightly higher incidence in colts
Where are ALDs most commonly seen?
Front limbs
-carpus, fetlock, tarsus
-carpal valgus most common, fetlock varus second most common
What is something that can make a foal appear like they have angulation?
Ligamentous joint laxity aka windswept
-due to incomplete endochondral ossification of the cuboidal bones and/or metacarpal/metatarsal bones
-worsens on weight beating and shifts when moving
-can lead to deformity if cartilages ossify in incorrect orientation
-most common in premature/dysmature foals
What are some perinatal factors that contribute to congenital limb deformities?
Intrauterine malpositioning, overnutrition of mare, hypoplasia of the cuboidal bones (due to prematurity, hypothyroidism, osteochondrosis), incomplete development of cuboidal bones
T/F: acquired ALDs are more common than congenital
True
Describe the pathogenesis of acquired ALDs
Asynchronous longitudinal growth of the physis or physeal dysplasia
- due to genetics, nutritional problems, physeal damage, physitis (septic or nah)
Can also be from traumatic luxation/fracture of physis, epiphysis or carpal/tarsal bones
What is Wolffs law
Bone growth increases in response to increased load
-causes exacerbation of damage when growing
-can use to target interventions
If you can straighten the limb easily on physical exam, what is the diagnosis?
Joint laxity
What radiographic views should you take when working up a ALD case?
DP and lateral views while weight bearing
- use large plates if available or hold plate on diagonal
What things are you looking for on radiographs of ALDs?
Pivot point: find by bisection long bones above and below joint
Degree of angulation (mild <5, severe >15)
T/F: mild varus may be protective for carpal injury
False- valgus may be protective
-varus in carpus is BAD
What are some possible radiographic findings for angular limb deformities?
-flaring and sclerosis of the metaphysis
-indistinct physic, irregular width of growth plate
-wedge shape and flaring of epiphysis with fracture lines
-cuboidal bones with abnormal shape, hypoplastic, collapsed or subluxated
-MTII or IV have a shorter or wider joint space
-bone cortex has diaphyseal remodeling
-may see complete ulna or fibula
What are the goals of treatment in angular limb deformity cases?
Improve conformation, halt worsening of angulation, prevent secondary changes, improve athletic performance
-more intervention required with older foals or more severe angulation
T/F: hypoplastic cuboidal bones and crush injury has a good prognosis
false- poor athletic prognosis depending on degree of angulation
What is the cause of sickle hock?
Crush injury at on the dorsal aspect of the tarsus due to incomplete ossification of the tarsal bones
-leads to OA and lameness
What is a method to prevent cuboidal bone fracture in foals?
Tube casts
Match the following with the proper treatment
A. Varus 1. Medial extension
B. Valgus 2. Lateral extension
A- 2
B-1
What are some rules for glue on shoes?
10 days on, 10 days off
-limit normal hoof wall growth
-have to be removed with hoof nippers
What are some of the surgical treatment options for angular limb deformities?
- Periosteal transection and elevation-causes growth acceleration on the concave side, perform laterally for valgus deformity
- Transphyseal bridging: growth retardation on the convex side, perform medially for valgus deformity (two screws with wire across physis or single positional screw across one side)
- Wedge osteotomy-if in diaphysis
What are some of the main considerations of transphyseal bridging?
Very effective if enough growth can occur
-monitoring of the foal is critical
-need to restrict exercise to prevent implant fatigue
-need a second surgery to remove implants
-implants can become infected
-local inflammation and scarring are possible
-bilateral or multiple TPBs may need to be removed at different times
-overcorrection is possible with this technique
When do fetlock deformities need to be corrected by?
Treatment needs to start by 30 days as the majority of growth is completed by 90 days
When do you need to start treating carpal and tarsal deformities?
By 4 months of age
T/F: the more proximal the pivot point, the poorer the prognosis
False- the more distal, the worse the prognosis
What is the etiology behind tendon and ligament laxity?
Musculotendinous weakness
- can be idiopathic, due to a lack of exercise, systemic illness, or from bandaging or casting
-congenital primarily but can be acquired
What are the clinical signs associated with digital hyperextension deformities?
Walking on heel bulbs, no weight on toe
What can cause the acquired form of tendon/ligament laxity?
Hoof overgrowth or bandaging/casting for a long period of time
Describe the treatment options for tendon/ligament laxity.
-moderate exercise, trimming feet, therapeutic shoeing, light bandages to protect skin if needed
-heel extensions to create lever that brings toe down
-good prognosis
What is the primary pathology associated with “contracted tendons” or flexural deformity?
Don’t trust the name, this is due to a mismatch between the length of tendons compared to bones
What do flexural deformities result in?
Persistent hyperflexion of the joint (distal interphalangeal joint, fetlock joint, carpus)
-can be congenital or acquired
-hind limb affected more than front limbs
-if can straighten at surgery there is a better prognosis
What are the most common flexural deformities that are congenital?
Carpus (when <1 month) > front fetlock > hind fetlock > pastern > coffin
What are the most common acquired deformities?
Coffin when young (1-4 mo)> front fetlock > fetlock
What are some of the potential causes for congenital flexural deformities?
Uterine malpositioning, genetic influences, teratogens, disease in mare, locoweed ingestion in mare, sudan grass ingestion by mare, idiopathic
What are some of the causes of acquired flexural deformities?
-growth disparity between bones and tendons/ligaments, pain (due to physitis, OCD, septic arthritis, wound, hoof pain or contralateral limb overload)
What are the most common structures involved with flexural deformities?
SDFT, DDFT, ulnaris lateralis, joint capsule
What are some of the main clinical signs associated with flexural limb deformities of the coffin joint?
Walking on toes, unable to place heel fully on ground, club foot, excessive toe wear
What is the difference between stage 1 and stage 2 DIP joint FD?
Stage one- dorsal hoof wall angle to the ground is <90 degrees–> good prognosis
Stage 2- dorsal hoof wall angle >/= 90 degrees –> poor prognosis
What are some characteristics associated with flexural limb deformities of the fetlock joint?
Fetlock angle when viewed from the side is upright or knuckled over
-DJD may be present in severe cases
What are some characteristics associated with carpal flexural deformities?
Buckling/flexion at the carpus, severe cases may be recumbent
-if manual reduction is possible there is a good prognosis
-if manual reduction is not possible there can be a fair prognosis but the longer the duration without trt prognosis is worsened
-look to see if there is incomplete cuboidal bone ossification present
What are some of the treatments for congenital flexural deformities?
-assistance to nurse
-increase exercise
-NAIDS
-oxytet (chelates calcium leading to musculotendinous relaxation)
-toe extension shoes
-splints or casts
-surgery if necessary
What are the shoeing options for treatment of coffin joint flexural deformities?
Lower the heel to encourage tendon stretch
-or put cup on toe with shoe extension or place equilox on end of toe
What are the main treatment principles with acquired flexural deformities?
-correct the nutritional imbalances and energy excess
-correct possible underlying causes
-use hoof trimming and toe extensions
-splinting and casting
-NSAIDs
When should you pursue surgical treatment in flexural deformity cases and what are the options available?
-perform when conservative treatment is not effective or the deformity is severe or rapidly worsening
-options are distal check ligament desmotomy for coffin joint, proximal check ligament desmotomy for the fetlock, or cutting ulnaris lateralis or flexor carpi ulnaris for carpal joint deformities
What are some complications of check ligament desmotomy?
cosmetic blemish
-surgical site infection
-carpal sheath breach
-unsuccessful procedure
