P.A.U.L. – Proximal Abducting Ulnar Osteotomy
Elbow Dysplasia & Medial Compartment Disease

One of the most common causes of fore limb lameness in the dog is Elbow Dysplasia. Elbow Dysplasia is a generic term meaning arthritis in the elbow joint. As in people, arthritis in the dog is painful, resulting in intermittent and persistent lameness, especially following physical activity.

Elbow Dysplasia has 4 developmental causes:

  1. Osteochondritis Dissecans (OCD)
  2. Ununited Anconeal Process (UAP)
  3. Fragmented Coronoid Process (FCP)
  4. Elbow Incongruency

Elbow Dysplasia that develops as a result of one or a combination of OCD, FCP, and Elbow incongruency is referred to as Medial Compartment Syndrome. Put simply, elbow dysplasia is early onset arthritis resulting from the abnormal development of the elbow joint. It is believed to be due to a combination of genetic factors, diet, rapid growth, and/or trauma.

Signs of Medial Compartment Disease:

  • sudden and/or gradual lameness on one or both forelimbs
  • stiffness and/or decreased range of motion after long periods of rest
  • forelimb lameness following exercise
  • initial signs may appear between 5-12 months of age

Consequences of Elbow Dysplasia

  • Cartilage deterioration releases a combination of inflammatory factors from the ligament.
  • Increasing instability of the joint from the damaged cartilage causes arthritis to develop quickly within the joint.
  • Every time the pet bears weight on the affected leg, abnormal or overloading of the medial compartment occurs. This abnormal loading often leads to concurrent cartilage erosions (often full thickness) and possible fragmentation of the medial coronoid. Once the cartilage is damaged arthritic change accelerates and perceived pain worsens.
  • a vicious cycle of compensation related damage leads, in many instances, to debilitating lameness.

Treatment Options:

Elbow dysplasia and medial compartment disease is a condition in need of a better treatment. At the moment relatively few options are available for these patients. Treatment options to minimize lameness range from conservative treatment, prescribing pain management drugs and special diets, to aggressive surgical treatment, cutting bone to altar joint biomechanics and even total elbow replacement. Although pain management drugs may help the dog feel better and cope with a bad elbow, they do not alter the progression of disease. The PAUL is a novel new palliative technique for the treatment of this lameness, showing particular benefit in younger patients, treated prior to the advanced stages of osteoarthritis.


The PAUL technique was developed on the basis of several observations and biomechanical analysis of the canine elbow joint:

  • A consequence of medial compartment disease, a subset of elbow dysplasia, is medial collapse of the contact mechanics of the elbow joint;
  • Medial collapse overloads the medial compartment, exacerbating existing lameness and joint pain;
  • A slight abduction, by 4 – 6 degrees, of the ulna results in an unloading of the medial compartment, alleviating pain;


The PAUL involves an osteotomy of the proximal portion of the ulna. A specially designed ALPS PAUL plate is fixed to impose a corrective limb alignment, aimed at unloading the medial compartment. This new alignment unloads the medial compartment, alleviating lameness, stiffness, and joint pain.