Elbow Dysplasia Surgical Option 3. Ununited Anconeal Process (UAP)

Question 1

What is UAP

Answer 1

At the proximal end of the ulna is the anconeal process. There is a growth plate between the anconeal process and the rest of the ulna. When the anconeal process does not fuse with the rest of the ulna, it is called an Ununited Anconeal Process. This causes irritation and instability for the patient. A diagnosis cannot be made until after 4-5 months of age, as the anconeal process is not fully fused until this time.

Question 2

List the 4 surgical procedures

Answer 2

1. Remove the anconeal process (loss of normal joint congruity). The anconeal process should be removed if it has changed shape or is no longer viable bone.
2. Surgical reduction and lag screw fixation
3. Ulna osteotomy with lag screw fixation
4. Ulna osteotomy (proximal): This involves a perpendicular or oblique cut in the ulna to reduce the force on the anconeal process and restore congruity. When done as a standalone procedure spontaneous fusion of the anconeal process should occur. Some veterinarians may place an intramedullary pin to stabilise the cut, but pin removal is required later.

Question 3

Patient Prep

Answer 3

The patient is clipped from the shoulder to the carpus, including the circumference of the limb.

Question 4

Patient Positioning - lateral

Answer 4

For the lateral approach the patient is placed in lateral recumbency with the affected limb uppermost and suspended for draping.

Question 5

Patient Positioning - medial

Answer 5

For the medial approach the patient is placed in dorsal recumbency with the limb suspended for draping.

Question 6

Instruments / Materials

Answer 6

The surgical approach to UAP will decide which instruments are required. Each of these procedure should have a general kit, four quarter draping as well as selective advanced instrumentation.

For an ulna osteotomy Gigli wire, an oscillating saw, Jacobs chuck and IM pins are required. For ulna osteotomy with lag screw fixation all the same instruments are required as well as the lag screw and a drill guide.

For removal of the anconeal process the Rochester Ochsner forceps will be required.

Question 7

Post op care

Answer 7

Strict rest for 4-6 weeks