The most common location for an angular limb deformity (although they can affect any of the long bones) is the radius and ulnar due to any asynchronous growth between these two bones.
Premature closure of either the distal radial or ulnar (most common) growth plate (or both), occurs most frequently. The proximal radial growth plate is less likely affected. The aetiology can be traumatic, metabolic or genetic.
Chondrodystrophic breeds e.g. Basset Hound, Dachshunds, Beagles etc are prone. When the distal ulnar growth plate is involved, the deformity that results typically causes limb shortening, radial procurvatum, external rotation and carpal valgus. These deformities can affect the elbow or carpus and result in painful osteoarthritis and ongoing lameness. Treatment depends on the age and temperament of the patient, the availability of implants, the exact nature of the deformity (this requires complex CORA-based calculations to be performed), and whether the deformity requires gradual versus acute correction.
They can be complex surgeries, requiring a lot of planning. We will on occasion use CT-reconstructed 3D printed bone models for planning and 3D printed guides are an area of research in this field.
Physical examination: The key for these patients is a thorough examination of the joints, typically by placing each joint through it's range of motion and checking for pain. If the deformity is bilateral, it may be more difficult to detect lameness during gait examination, but perform a careful gait examination. My tip for tricky gait examinations, is to slow-motion iphone record the gait. In my experience, some owners think these deformities are ‘normal for the dog’ or they were ‘born that way’. Sometimes they only realise the dog is in pain when you manipulate the joints in the consult. Also quiz the owners for any of the classic signs of osteoarthritis (slow to rise, stiffness after rest, lameness that is worse after longer periods of exercise, reluctance to jump etc). In puppies, the development of these deformities warrants urgent intervention. In some cases, a more simple ulnar ostectomy can resolve the problem if there is still growth potential. So with puppies, do not take a wait and see/NSAID-trial approach. Take radiographs as a first step and consult with a surgeon in regards to the best option. In addition, any puppy that presents for a forelimb lameness should be warned about the risk of growth plate damage that may not be detectable on the radiographs. Watch these puppies carefully as they grow (for limb length discrepancy, pain, ongoing lameness, carpal valgus) and act appropriately.
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