Chuck Walls, DVM, DACVS
Effective modalities for treatment of chronic elbow arthrosis in the dog have generally been lacking compared to surgical treatment of advanced arthrosis of other joints such as the hip. Medical management has greatly improved our treatment of chronic arthritis with the combination of NSAIDS, nutraceuticals, Adequan, intraarticular joint fluid replacement therapy (Synvisc), acupuncture, physical rehabilitation and activity modulation, specific diet therapies, herbal therapies, and most importantly, weight loss. Despite this multimodal approach to the treatment of arthritis, elbow disease continues to have an adverse affect on our patients’ activity level and quality of life. More recently however, new surgical advances in elbow surgery have begun to show promise in the effective treatment of chronic elbow arthritis. Elbow anatomy and physiology of function.
The elbow joint is unique, as it is a three bone hinge joint which not only allows for flexion and extension but also pronation and supination throughout most of its normal range of motion. Axial weight bearing forces, once thought to be primarily borne by the radius, have more recently been shown to be distributed almost evenly between the radius and ulna. Within the ulna, weight bearing is concentrated in the medial compartment known as the medial coronoid region. In the canine elbow, “Elbow Dysplasia” (ED) of the elbow results from some form of humeral-ulnar conflict (HUC) resulting in varying degrees of elbow arthritis due to presumed abnormal weight bearing loads. There are several hypotheses as to the cause of HUC which ultimately can result in chronic elbow arthritis. These range from radioulnar length discrepancies, radio-ulnar incongruency, ulnar notch shape abnormalities, primary rotational instability of the radius and ulna and potential musculotendious mismatch. Traditionally ED has been defined as 1) medial coronoid fragmentation, 2) OCD of the medial humeral condyle and 3) ununited anconeal process. In reality, these may just be differing manifestations of the underlying joint incongruity. The most common cause of acute and chronic elbow pain in the dog and ongoing arthrosis regardless of cause remains abnormal joint forces in the medial compartment of the elbow joint, represented by the medial coronoid and corresponding medial humeral condyle. The apparent lack of gross disease of the articular cartilage of the lateral compartment is both interesting and fortunate in relation to potential treatment options of the future.
Elbow replacement surgery
The unique configuration of the elbow joint has limited the advancement of elbow prosthetic development in both humans and animals for many years and still is in its infancy. Canine elbow replacement technology, starting with the Ralph Lewis total elbow in the early to mid 1980’s to the “Conzemius total elbow prosthetic” of the late 1990’s has gone through many revisions of both implants and techniques. Even so, the procedure remains one with a high degree with complications and failure. More recent advances in implant technology and the movement away from the lateral elbow approach to a less invasive medial elbow approach has shown promise. The “Tate” total elbow replacement, developed by Dr. Randy Acker, uses an innovative “cartridge” technology and biologic ingrowth components to accomplish alleviation of elbow pain related to chronic elbow arthritis. To date, still a relatively few dogs have had both short and long term follow up with this procedure and it is still recommended only for the patient with end-stage elbow arthrosis. However, we feel this is a real technological step forward and will probably be a standard method of treatment in the years to come. In the future, further advances in “hemi” arthroplasties (replacing only one component of the joint while leaving the other surface in its natural state) using this technology as well as concepts being developed by Kyon, makers of total hip replacement components, are sure to provide an even more reliable form of elbow replacement in the not too distant future.
Sliding Humeral Ostetotomy
The “Sliding Humeral Ostetotomy” (SHO) procedure was first conceived and developed by Dr. Kurt Schultz when he was at UC Davis in the late 1990’s. The concept was to try to develop a procedure that would produce the clinical advantages of transferring the weight bearing load of the elbow from the degenerative medial compartment to the healthier lateral compartment. To accomplish the biomechanical advantages of weight bearing load transfer to the lateral compartment of the elbow (Fig. 1) and create a stable osteotomy, Drs. Schultz and Noel Fitzpatrick– through many trials and error over a 10 year period–developed the current technique and locking SHO plate/screw fixation system in association with the biomedical company New Generations. The result of their hard work has been to create a technique and implant system with a high degree of clinical success and minimal complication when performed according to strict technical guidelines.
Well over 100 medium to large breed dogs with chronic elbow arthritis have undergone this procedure to date. The current technique involves initial arthroscopy to document that the articular cartilage wear was limited to the medial compartment of the elbow joint. The procedure then requires a medial approach to the mid-shaft of the humerus, partial application of the SHO plate. The plate is then use as its own “jig” to support and maintain alignment of the humerus while a transverse osteotomy is performed. The proximal segment of the humerus is then translated laterally to maintain at least 25% cortical contact, and the locking screws are placed to secure the plate to the bone. The patients are maintained on limited leash walks for 12 weeks and radiographic healing is usually complete by 12 weeks. (Fig. 2)
An initial study of 59 limbs that had undergone the SHO procedure showed that lameness improved in all limbs by 26 weeks, and that in 66% of elbows with long term follow up, the lameness resolved. Most of the working dogs were able to return to active hunting and significantly decreased or stopped the use of NSAIDS. A few dogs had second look arthroscopy that revealed the presence of fibrocartilage covering the previously identified full thickness articular cartilage wear of the medial humeral condyle and corresponding medial coronoid region, showing proof principle of the theoretical benefits of unweighting the medial compartment of the elbow by transferring the weight bearing load to the lateral compartment. (Fig. 3)
Dr. Chuck Walls, who is based out of our Concord facility, is a fellow of the SHO society and a managing partner at SAGE. He actively evaluates and accepts patients who might benefit from this procedure. The patients will be evaluated and monitored throughout the pre and post operative period and standardized data submitted to the SHO data base so that the success of the procedure can be determined amongst a large number of patients. If you have a patient with chronic unilateral or bilateral elbow arthritis secondary to elbow dysplasia who you think might benefit from this procedure, please have your clients schedule an appointment with Dr. Walls for an evaluation. Feel free to call any SAGE office if you have any questions regarding this procedure or any other orthopedic surgical questions you or your clients may have.