Ununited anconeal process
The condition is characterized by failure of the anconeal process to unite with the proximal ulna within the first 20 weeks of age.
The exceptions are the St. Bernard and Basset Hound, in which the anconeal process may fuse as late as 7 - 8 months. Males are most commonly affected, and bilateral involvement does occur.
Clinical signs are usually noted in puppies between 4 to 8 months of age. Joint effusion and varying degrees of pain on elbow manipulation may be noted.
While a presumptive diagnosis may be made upon assessment of breed and clinical examination (palpation of the shoulder is generally non-rewarding), radiography is necessary for definitive diagnosis. The presence of a lucent line on radiographs confirms the diagnosis in dogs over 6 months of age.
Treatment for young dogs is best achieved with corrective surgery, usually involving removal of the anconeal process, use of lag screws or use of dynamic proximal ulnar osteotomy to address the incongruity.
Removal of the anconeal process, while effective in some cases, does produce a more unstable joint, progression of degenerative joint disease, and clinical lameness in up to half of patients. Anconeal process removal is primarily reserved for older patients where severe degenerative changes preclude any semblance of a normal joint after ulnar osteotomy or lag screw fixation.
The placement of lag screws to stabilize the anconeal process have frequently resulted in the failure of the implant by breakage.
The decision on whether to do a proximal ulnar osteotomy alone or in conjunction with a lag screw appears to be based to some extent on the patient’s age. The younger the patient when the osteotomy is done the more likely radiographic fusion will occur, even when a screw is not placed.
- Vet Surgery Central
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