The ununited anconeal process is a condition in which a bony protuberance within the elbow becomes detached from the ulna bone. This loose bony fragment damages the inside of the joint.

Surgery is required to treat this condition.

Prognosis is dependant on the degree of damage to the joint that has been caused by the ununited anconeal process.

What is it?

• The anconeal process is a bony protuberance on the ulna (one of the three bones that make up the elbow joint) that fuses with the end of the ulna in normal dogs by 5 months of age.  If it does not fuse by 5 months, a diagnosis of ununited anconeal process (UAP) is made. 
• Like other types of elbow dysplasia, the cause for UAP is not known, although it is thought to be from unequal growth of the bones of the forearm (radius and ulna) or as a result of an osteochondrosis dissecans (OCD) lesion that prevents normal ossification (hardening) of the anconeal process.

Clinical Signs

• Large and giant breed dogs are most commonly affected, such as German shepherds, St. Bernards and Mastiffs, although other breeds can be affected as well, like Basset hounds. 
• Typically animals present between 6 and 12 months of age. 
• Owners often note that their dog is stiff in the morning and after rest and that lameness becomes worse following exercise.  The lameness can be in one or both front legs, and may come and go.  Some dogs swing the affected leg outward while walking; when standing some dogs also rotate their leg outward slightly (toes pointing away from them). 
• Your veterinarian may find signs of elbow dysplasia such as decreased range of motion of the elbow, crepitus (crackling), or signs of effusion (excess joint fluid) or swelling.

Diagnosis

• UAP is diagnosed by radiographic findings (x-rays): there will be a line separating the anconeal process from the ulna.   Again, it is important to note that this line is present in normal animals prior to 5 months of age.  Radiographs should be taken of both elbows, even if your dog is lame in only one leg, because this disease is commonly bilateral (affecting both elbows). 
• At the time UAP is diagnosed, there may already be signs of arthritis and degenerative joint disease (DJD) and other signs of elbow dysplasia.  Although results of blood work and urinalyses are often normal, your veterinarian may recommend them to rule out other underlying diseases and to ensure your pet is a good surgical candidate.

Treatment

• UAP is most often treated surgically in young animals, before secondary DJD develops.  There are a few different surgical options, however.  One technique is to surgically fasten the anconeal process to the ulna with a screw.  Another option is removal of the UAP.  A third option is limited to young dogs that are still growing.  This technique, called ulnar osteotomy, involves cutting of the ulna to relieve pressure on the UAP.  This can also be performed in conjunction with lag screw fixation. A fragmented coronoid process frequently accompanies the UAP and is treated with arthroscopic surgery.
  
• Following any of these procedures, it will be important for you to limit your dog’s activity for the first 6-8 weeks.  Most dogs are able to walk within the first day or so, but they should be limited to very short leash walks to urinate or defecate.  Rehabilitation therapy may include cold packing the elbow(s) for the first few days and warm packing for the next several days to weeks.  Flexing and extending the joint after warm packing will help minimize stiffness of the elbows.  After that, a gradual increase in activity will generally be allowed.  
  
• After surgery your dog may need long term medical therapy to help with elbow arthritis.  This often involves short term pain medication after surgery, such as Tramadol.  Tramadol can cause signs associated with stomach upset, and should be discontinued if constipation, vomiting or loss of appetite occur.  Dogs are often also put on a non-steroidal anti-inflammatory drug (or NSAID), which will help with both pain and inflammation. It, too, can cause stomach upset and if your dog experiences vomiting, diarrhea, black stools or loss of appetite, it should be discontinued and your veterinarian should be contacted. Another beneficial medication is gabapentin, which helps to block pain signals that are magnified in the spinal cord. This medication is generally well tolerated.
  
• Some dogs also benefit from a special diet that helps to promote joint health. This type of diet, which contains omega fatty acids, glucosamine and chondroitin sulfate, may help with joint pain and reduce the dose or need for long-term anti-inflammatories. 

Prognosis

• The majority of dogs (90%) improve with surgical intervention.  About 60% do not have any lameness following surgery, although all of these dogs will likely develop varying degrees of arthritis at some point and may require medical management of joint pain.

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