Elbow dysplasia is a term used to describe generalized osteoarthritis of the cubital (elbow) joint caused from atraumatic developmental abnormalities. Four common manifestations of elbow dysplasia include: ununited anconeal process (UAP), fragmentation of the medial coronoid process of the ulna (FMCP), osteochondritis dissecans of the medial aspect of the humeral condyle (OCD), and lastly articular cartilage anomaly or incongruence of the relationship with the intimate association of three bones of the elbow, humerus, radius, and ulna as they fit together to form the elbow joint. The International Elbow Working Group in 1993 agreed that elbow arthrosis caused by one of these four conditions is the manifestation of inherited canine elbow dysplasia.
WHO IS AFFECTED BY THIS CONDITION?
Elbow dysplasia is a common inherited condition and seen in Labrador Retrievers and Bernese Mountain Dogs more frequently, but it is seen in many breeds. This disease is bilateral in approximately 35% of affected dogs. Additionally, it can be seen concurrently with shoulder OCD; therefore, proper screening is indicated.
WHAT ARE THE SIGNS SEEN WITH THIS CONDITION?
Affected dogs are often lame or have an abnormal gait. The onset of pain is usually between 4-6 months of age however, with incongruence or fragmentation of the medial coronoid process, clinical signs may not be obvious until much older, for example 1-2 years of age. In some cases, we see late onset fragmentation of the coronoid process perhaps secondary to chronic increased stress in the medial compartment of the joint and /or traumatic insult to an otherwise abnormal joint. Delayed presentation of the lameness can manifest in middle or older patients as the arthritis advances.
HOW DO WE DIAGNOSE THESE PROBLEMS?
Diagnosis is primarily based on clinical signs and radiographic evaluation. Once the cause of lameness has been localized to the elbow, I recommend three radiographic views of the elbow for complete evaluation. Not all radiologists and groups who screen for elbow dysplasia require all three views. A standard lateral (100-120 degrees), craniocaudal (elbow in maximum extension with the olecranon in the exact center), and flexed lateral (inside angle <90 degrees). Radiographic appearance of elbow dysplasia is characterized by incongruity and osteoarthritis. It is recommended both elbows be radiographed due to the high incidence of bilateral disease.
Plain radiography can determine whether UAP, OCD, and some incongruence are present. However, the sensitivity for detecting FMCP with plain radiography is very low (25%) due to its anatomic location. Computer tomography (CT scan) approaches 90% or more sensitivity. Additionally, incongruence can be identified more easily with CT scan when the incongruence is more subtle. Incongruity may not always be grossly or radiographically evident as compensatory adjustments during growth may occur.
Early signs of incongruity or stress within the joint include increased bone density at the distal end of the trochlear notch in the ulna, osteophytes on the dorsal aspect of the anconeal process, lateral epicondyle ridge, lipping of the medial aspect of the medial coronoid process, and cranial aspect of the radial head.
On rare occassion, the cartilage surface may appear grossly normal, but microCT analysis reveals subchondral cracking in the bone of the coronoid process. This is why it is possible that exploration will not confirm 100% of the time that the medial coronoid process is normal even if no crack or fragment is seen in surgery.
WHAT ARE THE TREATMENT OPTIONS?
The devastating effects of degenerative joint disease of the elbow justify screening and early treatment. All immature dogs with FMCP, OCD, or UAP are all surgical candidates. Dogs with slight to moderate incongruity and minimal osteoarthritis have the most favorable prognosis. Mature dogs with mild to moderate osteoarthritis may also be considered for surgery. It is questionable whether or not mature dogs with severe osteoarthritis should be operated on. Conservative management should be considered. When UAP and FMCP are found concurrently, these patients seem to have the worse prognosis long term. Progression of osteoarthritis with elbow dysplasia can be expected, but most affected dogs manage to cope with the problem by limiting their exercise, weight control, and administering anti-inflammatory, analgesic, chondro-protective agents, and omega-3 fatty acids, to name a few.
WHAT ARE SOME OF THE MORE INNOVATIVE TREATMENTS OPTIONS AVAILABLE?
Each patient is unique based on the age of diagnosis, the severity of the osteoarthritis, and the specific problem(s) affecting the elbow joint. Each surgeon has a variable approach to the specific surgical recommendation dependent on the problem. Most agree that the joint should be explored (mini surgical approach or arthroscopy) and especially before severe osteoarthritis develops. In the case of FMCP, the fragment is removed and a technique called a BURP or bicipital ulnar tendon release may be performed. Evidence suggests this procedure decreases the stress in the medial compartment of the joint. Other newer techniques for the more severely arthritic elbows include the CUE or Canine Unicompartmental Elbow Resurfacing where a synthetic implant is placed in the medial compartment so that the pain from bone to bone contact is relieved. Other techniques for the end stage elbow include the PAUL or Proximal Abducting Ulnar osteotomy where the ulna bone is cut and a plate is placed so that the stress in the medial compartment is improved and the limb is more aligned. A SHO or Sliding Humeral Osteotomy is a technique whereby the humerus bone is cut and a special plate is applied that shifts the bone so that the stress on the medial compartment of the elbow is decreased during weight bearing. Lastly, regenerative medicine is becoming popular. Treatment options to help improve the environment in the joint to decrease inflammation and attempt to stimulate healing of abnormal tissues include Stem Cell Therapy. Although there is much work being done in these areas in both humans, and animals, we still do not have good consistently reproducible evidenced based medicine to show that these treatment modalities alter the outcome clinically in patients undergoing these treatments. Most of the evidence is anecdotal and via testimony.
Any young large to giant breed dog presented with forelimb lameness should be examined for elbow dysplasia. If clinical signs and radiographic findings support elbow dysplasia, all causes of elbow dysplasia should be ruled out. Confirmation of FMCP on plain radiographs may be difficult and CT scans can be considered if the client wants to ensure a higher probability prior to surgery. Many clients would rather use their financial resources for surgery and to explore the joint assuming there is high confidence based on clinical localization of the pain, repeated examfindings, and plain radiographic changes. In this surgeon’s experience, 90% of these situations result in finding the presence of a FMCP and the balance of the cases have no fragment grossly seen at the time of surgery but rather incongruity causing wear and osteoarthritis. These cases could still potentially fragment later.
WHAT IS DR. WILLER’S EXPERIENCE?
In general, in these younger patients we feel surgery is better than no surgery and we can expect some improvement at least short term and possibly long term. In the more mature patients with more advanced arthritis, surgery may or may not make a difference. We should go to surgery understanding that we may not make a difference. All surgeons know of many cases where they can say surgery markedly improved their patient for a variable length of time and in some cases actually resolved their lameness long term. We accept the fact that they will progress to some degree with arthritis over the years, but the goal is to maximize the chance that they will have the best result by intervening earlier than later.
I quote owners that the chances are approximately 1/3 of these cases we can significantly improve or resolve the lameness short term and probably long term, 1/3 of these cases we will improve to some degree for a variable length of time, and 1/3 we will not have changed the clinical signs. I suggest that in ~75% of the cases we will see improvement. The timing and degree of arthritis affect the outcome. In older dogs with more advanced arthritis, I quote 50% chance we may be able to help improve their clinical signs. The older more advanced end stage arthritic patients may need to have CUE, SHO, or PAUL. Currently FRMSS is not offering the salvage surgical options but as more evidence is published, we will introduce this into our practice.
My own technician’s dog had surgery for a FMCP in 2010 after a couple months of lameness not resolving with rest and medical management. “Molly” continues to be sound and she is extremely active with hiking, chasing balls, and high level activities. Again, this is a testimony, but these are examples of why most of us surgeons continue to recommend surgery over no surgery. We can site many of these examples just as we can site that some cases we did not resolve the lameness problem. Improvement is experienced in many cases.