Ulnar Ostectomy in Dogs

A dog's forelimb has two bones that stretch between the wrist and the elbow joint. They are the radius bone and the ulna bone. The ulna bone supports 20% of the animal's weight.

The upper ends of the radius and ulna bones connect with the lower end of the humerus bone, to form the dog's elbow joint. It is crucial that each bone fits correctly within the elbow joint to avoid abnormal tear on the joint, especially when a young dog's growth plates are active.

Growth plates are soft areas located at both ends of a young dog's long bones. They contain rapidly dividing cells which allow the bones to grow and become longer. The growth plates gradually close as the animal reaches puberty. 

If the growth plate of the radius bone is degraded while the dog is growing up, the pet may develop a shortened radius bone, shorter than the ulna bone, which will cause an imperfect fit on the elbow joint, generating lameness and further limb deformities.

Early corrective surgery is needed to remove a segment of the ulna bone, in relation to the radius. This procedure is called an ulnar ostectomy and can dramatically improve the lameness of the dog.

An affected dog will usually show lameness on the affected forelimb. The veterinarian will initially check the elbow for signs of swelling and will observe the dog's reaction to direct palpation of the area. If needed, X-rays will be scheduled, and a CT scan may also be used to help diagnose secondary issues such as a fragmented coronoid process within the elbow joint.

For the surgery, the dog will be given a sedative and will have an IV catheter placed. Oxygen, fluids and thermal support will be required. Medical equipment will be connected to monitor the pet's vital signs. The dog will be anesthetized.

The procedure will remove a segment of the ulna bone, below the elbow joint. The length of bone that is removed will be inversely proportional to the dog's age. The younger the dog, the larger the segment of bone that needs to be removed.

A pin will be placed in the ulna bone for alignment, and a fat graft may be required. Finally, the cut ends of the ulna bone will be pulled together with a thick nylon suture which will help the elbow joint assume a better fit immediately after surgery.

The overall prognosis for dogs who are seven months or younger is very positive and will have a good chance of complete recovery. Older dogs, especially those with severe leg deformities, have a more guarded prognosis. The sooner the procedure is performed, the better.

An ulnar ostectomy can correct the distortion of the radial bone, by allowing it to develop since it will no longer be restrained by a shortened, solid ulna.

Most dogs will return to controlled activity in two months and full activity in three to four  months. Athletic or very active dogs will recover full mobility in six months. However, the owner must consider that lameness might still occur after heavy activity.

An alternative treatment is to lengthen the radius bone, but this procedure is more complicated and should only be performed on dogs that have stopped growing.

The dog will have a soft padded bandage for two to three days to prevent seroma formation and will require a bandage around the leg or the use of an Elizabethan collar to prevent licking at the incision.

Sutures or staples are removed after ten days unless tissue glue or dissolving sutures were utilized.

The veterinarian will check the bandages, splints, and amount of swelling every week. Mild swelling may develop near the incision area or the lower part of the limbs.

Activity and exercise should be restricted for at least six to eight weeks since the excessive movement may inhibit graft vascularization, which can lead to displacement and subsequent premature union of the ulna.

If the dog is difficult to control or has an exceeding amount of energy, small amounts of a tranquilizer may be prescribed to help the animal during this confinement period. If needed, the veterinarian may advise boarding the dog for the first three weeks after surgery.

Between three and four weeks after surgery, progress radiographs are taken, and once again after three to four more weeks to ensure the fracture is healing properly.

Ulnar ostectomy is an expensive surgery. In most cases, an orthopedic surgeon will need to be consulted. The surgery can cost between $2,000 and $6,000, depending on the location, the age of the dog, the complexity of the deviation and the severity of the limb deformity.

Owners should also consider the additional costs of performing multiple radiographs and computerized tomography scans, which can add another $1,000 to $1,500 to the total cost.

Unlike human patients who can use crutches, a dog isn't aware of the procedure. The pet owner must restrict the animal's activity. Failure to do so can lead to delayed healing, the need to perform further surgery, or even fracture of the bone.

Delayed healing is the most common complication. However, in a small number of cases, the bone may not be able to heal and will require an additional procedure, usually a bone graft.

Infections are not common, but they can still happen and will affect the bone's ability to heal.

Forearm limb deformities are usually induced by a congenital defect that manifests during bone growth and bone formation. Breeds commonly affected are Bernese mountain dogs, dachshunds and Basset hounds.

Any dog that requires an ulnar ostectomy should not be used for breeding. Both parents should be retired from breeding as well.

In some patients, injury or mechanical trauma can also generate or increase the deformity. Jumping from heights and landing heavily on the forearm limbs should be avoided and young dogs should be restricted from agility exercises until they have finished growing and are skeletally mature, which is usually around 12 to 18 months of age.

An ulnar ostectomy is most effective in young dogs with a median age of 5 months and less than 25 degrees of carpal valgus. Owners should consider that a puppy's lameness will not go away on its own and in fact, should be addressed as early as possible.