The elbow joint is formed by the three main bones of the forelimb (antebrachium); the humerus, the radius, and the ulna and it functions as a hinge joint. The humerus, the bone of the upper arm, articulates (joins) with the two lower bones, the radius and ulna. This end portion of the humerus is called the humeral condyle, with a medial (inside portion, closer to the body) portion and a lateral (outer aspect) condylar component.
In some breeds of dogs, a small fissure is present between the medial and lateral aspect of this humeral condyle and can lead to pain in the joint, eccentric or uneven weightbearing, and lameness.
This fissure was previously thought to be a developmental condition (termed Incomplete Ossification of the Humeral Condyle), where the two portions of the condyle never fused properly during adolescence, but recent veterinary studies have shown that this fissure develops in previously normal elbow joints. The exact cause is unknown but is thought to be a result of uneven weightbearing upon the elbow joint. Terms such as intracondylar fissure and more recently humeral condylar fissure (HCF), are now used to refer to this condition. Certain breeds (e.g. Springer spaniel) are over-represented.
The end result of this fissure is instability in the bottom part of the humerus. This causes uneven weight bearing and load-sharing within the joint. Affected dogs demonstrate varying degrees of discomfort, pain, and lameness. The condition can affect both elbow joints, although more commonly one is more clinically significant at the time of presentation. HCF can progress to complete fracture of one or both portions of the humeral condyle and can even spread further up the humerus.
HCF is difficult to diagnose using plain radiography, as an x-ray beam can only pick up the fissure when directly perpendicular to it. For this reason, advanced imaging such as a CT scan is the most accurate way to diagnose this condition.
HCF can be treated surgically, by placement of a transcondylar (across the humeral condyle) screw to stabilise the bone. There are several screw types which have been used to increase stability. This implant helps prevent propagation of the fissure line to a fracture. Recent reports at veterinary conferences report that in clinically unaffected limbs, conservative or non-surgical treatment can be offered but the risk of fracture always remains. Surgery on both elbows can be performed at the same time if required.
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