Angular Limb Deformity

Angular Limb Deformity


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Basic Information  image



Definition


Angular limb deformities (ALDs) result in a limb deviation in the frontal plane either toward (varus) or away (valgus) from the body. They are often bilateral and are usually associated with growth centers, especially the epiphysis, but they can be diaphyseal. Not all ALDs are abnormal.



Synonym(s)




• Knock knees


• Cow hocks


• Toeing in or toeing out



Epidemiology



Genetics and Breed Predisposition




• Anecdotal evidence suggests ALD is genetic, but this is unproven.


• ALDs are most common in light-breed horses with fast growth rates such as Thoroughbreds and Quarter Horses, but they may occur in any breed.



Risk Factors




• Prematurity or dysmaturity, ligamentous laxity.


• For “windswept” foals, small uterine size in the mother and a lack of fetal activity are considered possible causes.



Associated Conditions and Disorders


Some degree of limb rotation is often associated with ALD. Inward rotation is usually associated with varus and outward rotation with valgus. Although most ALDs are bilaterally symmetrical, an uncommon manifestation of congenital ALD is windswept foals, in which paired limbs are deviated in one direction. Rarely, ALDs are the result of severe congenital developmental bone disorders.



Clinical Presentation



Disease Forms/Subtypes




• The most common congenital ALD is carpal valgus followed by fetlock valgus and varus.


• Much rarer is tibial valgus followed by varus.



History, Chief Complaint




• Congenital ALD may worsen during the first week of life because of the effects of gravity and asymmetric weight bearing.


• Severely affected foals may have difficulty nursing and ambulating.



Physical Exam Findings


Uncomplicated ALD in a neonate should not result in lameness or periarticular swelling. If caused by epiphyseal or physeal dysplasia, the limb examination results are normal but the deviation cannot be corrected manually. If caused by epiphyseal ligamentous laxity, the deviation can be corrected manually.



Etiology and Pathophysiology




• Most congenital ALDs are caused by some degree of immaturity of soft and hard tissues of limbs and possibly in utero positioning.


• The impact of genetics is more likely the result of breed influence for slender limbs and fast growth rather than an individual parent’s impact.

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Jul 24, 2016 | Posted by in SMALL ANIMAL | Comments Off on Angular Limb Deformity

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