Proximal Abducting Ulnar Osteotomy



Medial compartment disease of the canine elbow is a common, highly debilitating orthopedic condition in need of a better treatment. In an effort to address this need, Dr. Ingo Pfeil, Dresden, Germany, proposed a proximal ulna osteotomy, aimed at unloading the medial compartment, thus reducing pain and improving limb use and function.

The ALPS Proximal Abducting Ulnar Osteotomy (PAUL)* plate, invented and developed by Dr. Ingo Pfeil and KYON Veterinary Surgical Products, imposes a corrective limb alignment, aimed at unloading the medial compartment. Dr. Pfeil began clinical use of the PAUL technique in 2007. In 2010 KYON initiated the next phase of development, expanding to ~30 surgeons worldwide. By early 2012, ~300 cases had been treated. The procedure, as currently practiced with the KYON Advanced Locking Plate System** (ALPS) implants, presents relatively low morbidity and is meeting the expectations of the early adopters in terms of clinical improvement.

The Advanced Locking Plate System (ALPS) reduces iatrogenic trauma and offers greater versatility and increased overall stability, resulting in accelerated fracture healing. The ALPS plating system builds on research and development work done on the PC-Fix (Point Contact Fixator) in the 1980s and 1990s at the AO Research Institute, Davos, Switzerland. Numerous publications have documented the PC-Fix design and clinical results.

Slobodan Tepic, Dr. Sci., CTO, KYON AG, who conducted the research on PC-Fix, has developed the Advanced Locking Plate System (ALPS) as a “biological internal fixation” system, designed from conception to preserve the vascular supply, increase resistance to infection and accelerate healing. “Biological internal fixation” involves the use of locked internal fixators, which have minimal implant-to-bone contact, long-span bridging and fewer screws for fixation.[1]
*Patent Pending
**Patented/Patent Pending

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[1] – Perren SM, – Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: choosing a new balance between stability and biology. J Bone Joint Surg Br. 2002 Nov;84(8): 1093-110.


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 Dessicans (OCD)
  2. Ununited Anconeal Process (UAP)
  3. Fragmented Coronoid Process (FCP)
  4. Elbow In-congruency

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 fore limbs
  • stiffness and/or decreased range of motion after long periods of rest
  • fore limb 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 alter 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 paliative technique for the treatment of this lameness, showing particular benefit in younger patients, treated prior to the advanced stages of osteoarthritis.

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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.

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Dr. Ingo Pfeil, Dresden, Germany, began clinical use of the PAUL technique in 2007 to refine the surgical approach and the implant design. Trial and error in the first two years was followed by a more focused development phase and the production of unique ALPS plates.

Controlled clinical release of the PAUL system was initiated in early 2010, expanding to ~30 surgeons worldwide. By early 2012, ~300 cases had been treated. Clinical experience in the United States, Europe and Japan demonstrated reduced complexity and morbidity of the procedure in comparison to other corrective surgical techniques and is meeting the expectations of the early adopters.

Early complication rates were manageable. In most cases, complications were related to technical errors and implant design. Positive reports on the technique and short-term clinical outcomes are encouraging.



The following database, contains contact information for surgeons performing the Proximal Abducting Ulnar Osteotomy.

Please contact to update contact information.


Starke A1, Böttcher P, Pfeil I.
[Comparative radiologic examination of the canine elbow with and without elbow dysplasia under standardized load].
[Article in German] Tierarztl Prax Ausg K Kleintiere Heimtiere. 2014;42(3):141-50.
1Andreas Starke, Fischhausstraße 5, 01099 Dresden, E-Mail:


Starke A1, Böttcher P, Pfeil I.
[Radiologic quantification of the elbow conformation with a new method for acquiring standardized x-rays under load. Reference valus for medium sized and large dogs without dysplasia of the elbow joint].
[Article in German] Tierarztl Prax Ausg K Kleintiere Heimtiere. 2013;41(3):145-54.
1Tierärztliche Klinik Dresdner Heide, Dresden.


Fitzpatrick N1, Yeadon R, Smith T, Schulz K.
Techniques of application and initial clinical experience with sliding humeral osteotomy for treatment of medial compartment disease of the canine elbow.
Vet Surg. 2009 Feb;38(2):261-78. doi: 10.1111/j.1532-950X.2008.00493.x.
1Fitzpatrick Referrals, Eashing, UK.


Mason DR1, Schulz KS, Fujita Y, Kass PH, Stover SM.
Measurement of humeroradial and humeroulnar transarticular joint forces in the canine elbow joint after humeral wedge and humeral slide osteotomies.
Vet Surg. 2008 Jan;37(1):63-70. doi: 10.1111/j.1532-950X.2007.00349.x.
1JD Wheat Veterinary Orthopedic Research Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA.


Mason DR1, Schulz KS, Fujita Y, Kass PH, Stover SM.
In vitro force mapping of normal canine humeroradial and humeroulnar joints.
Am J Vet Res. 2005 Jan;66(1):132-5.
1Department of Clinical Sciences, Iowa State University, Ames, IA 50011, USA.


Fujita Y1, Schulz KS, Mason DR, Kass PH, Stover SM.
Effect of humeral osteotomy on joint surface contact in canine elbow joints.
Am J Vet Res. 2003 Apr;64(4):506-11.
1Department of Surgical and Radiological Science, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.