Angular and Flexural limb deformities

Question 1

What are the 3 types of foal growth abnormalities?

Answer 1

Angular limb deformities, tendon and ligament laxity, flexural deformities (contracted tendons)

Question 2

What is the definition of ALD?

Answer 2

Medial or lateral deviation to the long axis of the bone in the frontal plane

Question 3

What is lateral deviation distal to the point of deviation called

Answer 3

VaLgus

Question 4

What is medial deviation distal to the point of deviation called?

Answer 4

varus

Question 5

What usually accompanies an ALD in foals?

Answer 5

Rotational deformity (outward or inward rotation)
-can grow out of these
-usually due to chest being so wide compared to limbs

Question 6

What is the typical signalment for ALDs?

Answer 6

Usually young foals (rapidly growing), all breeds affected, slightly higher incidence in colts

Question 7

Where are ALDs most commonly seen?

Answer 7

Front limbs
-carpus, fetlock, tarsus
-carpal valgus most common, fetlock varus second most common

Question 8

What is something that can make a foal appear like they have angulation?

Answer 8

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

Question 9

What are some perinatal factors that contribute to congenital limb deformities?

Answer 9

Intrauterine malpositioning, overnutrition of mare, hypoplasia of the cuboidal bones (due to prematurity, hypothyroidism, osteochondrosis), incomplete development of cuboidal bones

Question 10

T/F: acquired ALDs are more common than congenital

Answer 10

True

Question 11

Describe the pathogenesis of acquired ALDs

Answer 11

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

Question 12

What is Wolffs law

Answer 12

Bone growth increases in response to increased load
-causes exacerbation of damage when growing
-can use to target interventions

Question 13

If you can straighten the limb easily on physical exam, what is the diagnosis?

Answer 13

Joint laxity

Question 14

What radiographic views should you take when working up a ALD case?

Answer 14

DP and lateral views while weight bearing
- use large plates if available or hold plate on diagonal

Question 15

What things are you looking for on radiographs of ALDs?

Answer 15

Pivot point: find by bisection long bones above and below joint

Degree of angulation (mild <5, severe >15)

Question 16

T/F: mild varus may be protective for carpal injury

Answer 16

False- valgus may be protective
-varus in carpus is BAD

Question 17

What are some possible radiographic findings for angular limb deformities?

Answer 17

-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

Question 18

What are the goals of treatment in angular limb deformity cases?

Answer 18

Improve conformation, halt worsening of angulation, prevent secondary changes, improve athletic performance
-more intervention required with older foals or more severe angulation

Question 19

T/F: hypoplastic cuboidal bones and crush injury has a good prognosis

Answer 19

false- poor athletic prognosis depending on degree of angulation

Question 20

What is the cause of sickle hock?

Answer 20

Crush injury at on the dorsal aspect of the tarsus due to incomplete ossification of the tarsal bones
-leads to OA and lameness

Question 21

What is a method to prevent cuboidal bone fracture in foals?

Answer 21

Tube casts

Question 22

Match the following with the proper treatment

A. Varus 1. Medial extension
B. Valgus 2. Lateral extension

Answer 22

A- 2
B-1

Question 23

What are some rules for glue on shoes?

Answer 23

10 days on, 10 days off
-limit normal hoof wall growth
-have to be removed with hoof nippers

Question 24

What are some of the surgical treatment options for angular limb deformities?

Answer 24

1. Periosteal transection and elevation-causes growth acceleration on the concave side, perform laterally for valgus deformity
2. 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)
3. Wedge osteotomy-if in diaphysis

Question 25

What are some of the main considerations of transphyseal bridging?

Answer 25

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

Question 26

When do fetlock deformities need to be corrected by?

Answer 26

Treatment needs to start by 30 days as the majority of growth is completed by 90 days

Question 27

When do you need to start treating carpal and tarsal deformities?

Answer 27

By 4 months of age

Question 28

T/F: the more proximal the pivot point, the poorer the prognosis

Answer 28

False- the more distal, the worse the prognosis

Question 29

What is the etiology behind tendon and ligament laxity?

Answer 29

Musculotendinous weakness - can be idiopathic, due to a lack of exercise, systemic illness, or from bandaging or casting -congenital primarily but can be acquired

Question 30

What are the clinical signs associated with digital hyperextension deformities?

Answer 30

Walking on heel bulbs, no weight on toe

Question 31

What can cause the acquired form of tendon/ligament laxity?

Answer 31

Hoof overgrowth or bandaging/casting for a long period of time

Question 32

Describe the treatment options for tendon/ligament laxity.

Answer 32

-moderate exercise, trimming feet, therapeutic shoeing, light bandages to protect skin if needed -heel extensions to create lever that brings toe down -good prognosis

Question 33

What is the primary pathology associated with "contracted tendons" or flexural deformity?

Answer 33

Don't trust the name, this is due to a mismatch between the length of tendons compared to bones

Question 34

What do flexural deformities result in?

Answer 34

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

Question 35

What are the most common flexural deformities that are congenital?

Answer 35

Carpus (when <1 month) > front fetlock > hind fetlock > pastern > coffin

Question 36

What are the most common acquired deformities?

Answer 36

Coffin when young (1-4 mo)> front fetlock > fetlock

Question 37

What are some of the potential causes for congenital flexural deformities?

Answer 37

Uterine malpositioning, genetic influences, teratogens, disease in mare, locoweed ingestion in mare, sudan grass ingestion by mare, idiopathic

Question 38

What are some of the causes of acquired flexural deformities?

Answer 38

-growth disparity between bones and tendons/ligaments, pain (due to physitis, OCD, septic arthritis, wound, hoof pain or contralateral limb overload)

Question 39

What are the most common structures involved with flexural deformities?

Answer 39

SDFT, DDFT, ulnaris lateralis, joint capsule

Question 40

What are some of the main clinical signs associated with flexural limb deformities of the coffin joint?

Answer 40

Walking on toes, unable to place heel fully on ground, club foot, excessive toe wear

Question 41

What is the difference between stage 1 and stage 2 DIP joint FD?

Answer 41

Stage one- dorsal hoof wall angle to the ground is <90 degrees--> good prognosis Stage 2- dorsal hoof wall angle >/= 90 degrees --> poor prognosis

Question 42

What are some characteristics associated with flexural limb deformities of the fetlock joint?

Answer 42

Fetlock angle when viewed from the side is upright or knuckled over -DJD may be present in severe cases

Question 43

What are some characteristics associated with carpal flexural deformities?

Answer 43

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

Question 44

What are some of the treatments for congenital flexural deformities?

Answer 44

-assistance to nurse -increase exercise -NAIDS -oxytet (chelates calcium leading to musculotendinous relaxation) -toe extension shoes -splints or casts -surgery if necessary

Question 45

What are the shoeing options for treatment of coffin joint flexural deformities?

Answer 45

Lower the heel to encourage tendon stretch -or put cup on toe with shoe extension or place equilox on end of toe

Question 46

What are the main treatment principles with acquired flexural deformities?

Answer 46

-correct the nutritional imbalances and energy excess -correct possible underlying causes -use hoof trimming and toe extensions -splinting and casting -NSAIDs

Question 47

When should you pursue surgical treatment in flexural deformity cases and what are the options available?

Answer 47

-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

Question 48

What are some complications of check ligament desmotomy?

Answer 48

cosmetic blemish -surgical site infection -carpal sheath breach -unsuccessful procedure