Elbow joint dysplasia (elbow dysplasia, ED)Elbow joint dysplasia (ED or elbow dysplasia) includes several growth-related disorders of the elbow joint in dogs. Like hip dysplasia, it is hereditary. Depending on the disease and its severity, it leads to mild to severe lameness and elbow arthrosis. Therapeutic procedures are available for the various disorders of the complex. This usually improves the symptoms. However, since the joint is not "cured" by any currently available method, it is not possible to treat it If the dog is not able to become lame, the formation of arthrosis is not prevented by any method of treatment. However, the disease process can often be delayed, so that many dogs can lead a normal life for many years.
Three bones are involved in the formation of the elbow joint: the humerus, the ulna, and the radius. In order for movement to be frictionless, the articular surfaces of these bones must fit together exactly and be covered with an intact cartilage layer.
The illustration shows the X-ray image of a normal elbow joint.
If a step forms in the joint and/or the cartilage is damaged in some other way, the result is joint inflammation and, in the long term, the formation of osteoarthritis. The animals are in pain and lame. Elbow joint dysplasia is a malformation of the joint. The causes are manifold. Not completely clarified. A step formation, i.e. a not exact matching of the joint surfaces to each other, is amed as an essential factor. The disease can have different manifestations. The most common are: "fragmented coronoid process" (FCP or FPC), "isolated anconal process" (IPA), "osteochondrosis dissecans" (OCD) and the "incongruity".
Causes and everyday consequences
Whether a dog develops ED and what course the disease takes depends on many factors, of which only a few are mentioned here. Much in the history of the disease is also still unexplained. It is certain that the hereditary component is the most important for the development of elbow dysplasia. The inheritance is complex and not every dog whose parents are ED carriers will develop ED themselves. Conversely, parents who are ED-free themselves can also inherit the condition and produce affected offspring. Another factor is the rapid growth of the affected dogs, in which the feeding has a significant share. Many dogs are fed high-energy "puppy chow" for far too long. This leads to growth imbalances between bone and between bone and cartilage, and between muscle and bone. Obesity also plays an important role. Often underestimated role. It is mainly large dogs of rather compact body shape that are affected, while more muscular animals, less prone to obesity, tend to suffer less frequently from elbow dysplasia. Also the frequently encountered desire that certain breeds grow as fast as possible in order to achieve as large a body size as possible at an early stage is detrimental to the musculoskeletal system, including the elbow joints. Over-supply of feed additives such as calcium or certain vitamins can trigger or aggravate various skeletal disorders – a connection is also suspected with elbow dysplasia. Constant overstraining of the musculoskeletal system can aggravate or trigger skeletal diseases. Also discussed as a factor in the development of elbow disease. There are numerous other factors that are probably involved in the development of elbow dysplasia. The origin of the disease is therefore complex. However, a hereditary basis is always amed, all other factors are rather additional factors, which are involved in the individual expression of the disease in the individual patient. It is a fact that there are cases of severe elbow dysplasia despite optimal posture. In the same way, there are dogs in which the disease is very mild, although everything has been done wrong according to the above theories. It is therefore impossible to predict in individual cases whether a dog will develop elbow dysplasia and what course it will take.
Forms of elbow joint dysplasia
1. Isolated proces anconeus
In this form of ED, a bony process (proces anconaeus) of the ulna has not grown during growth. Different causes are discussed. The connection to the ulna may be relatively firm or may not exist at all. In all cases, however, the mobile articular process results in persistent irritation of the joint with rapid formation of usually severe osteoarthritis. Most dogs with IPA are significantly lame. Have significant pain in the affected joint.
The illustration shows a radiograph of an elbow joint with an isolated proces anconaeus (IPA). The area where ossification has not taken place is outlined in red.
2. Osteochondrosis dissecans
The disease develops when a developmental disorder leads to the formation of a cartilage layer that is too thick and a disturbance in the supply of nutrients to the deep cartilage layer. If this dies, one speaks of an "osteochondrosis". The dead cartilage area detaches from the underlying bone. Inflammation of the joint occurs. If a cartilage scale lifts off, one speaks of "Osteochondrosis dissecans". In the affected area of the joint, the bone is exposed. The altered or detached cartilage can no longer perform the important tasks of shock absorption, formation of a gliding surface during joint movement, etc., and can therefore no longer be used. no longer fulfil. As a rule, there is a rapidly progressing arthrosis and joint destruction.
The figure shows an x-ray of a dog with OCD of the elbow joint. The normally smooth joint contour shows a defect in the area of the red marking.
3. Fragmented coronoid process
This condition probably arises when the ulna and radius do not have an even contour, but the ulna "protrudes" a bit. Another possibility is that the recess for the upper arm is too narrow. In both cases, there is an overload of a process of the ulna, the "coronoid process. There are many other theories of origin. However, the consequence is always the same: Cartilage and bone are damaged in the tip of the coronoid process, often resulting in the formation of small bone-cartilage fragments. In this case, a "Fragmented Coronoid Process" is present in the true sense of the word. Again, there is inflammation of the joint resulting in pain, lameness and osteoarthritis. In no other form of elbow dysplasia are the symptoms so different in different patients as in FCP. There are animals that are symptom-free for many years, and in which only late slight changes in the X-ray are noticeable. Other animals show severe lameness and arthrosis of the joint at an early age. Most often, however, patients present as young dogs toward the end of growth. Already have significant changes at this time – both in gait and x-rays.
The figure shows the arthroscopic image (arthroscopy = joint endoscopy) of an elbow joint with a fragmented coronoid process (FCP, FPC). In this case, the cartilage surfaces are only slightly altered.
This term refers to a step formation between the ulna and radius. In a minor form, step formation is probably also involved in the development of FCP and possibly also IPA. However, in the case of "incongruity" as an independent manifestation of FCP, the step is significant and the actual cause of the lameness. Affected animals do not have to have FCP or IPA, but the step formation leads to uneven loading of the joint surfaces and thus to overload zones in which cartilage and underlying bone are damaged. This in turn leads to inflammation of the joint and consequently to lameness, pain and arthrosis.
The figure shows an x-ray of a dog with a distinct step in the elbow joint. In this case the diagnosis is clear. Often, however, a step in the X-ray image is only faked, because several bone structures are superimposed.
All manifestations are in principle independent diseases. Nevertheless, they are summarized by the collective term "elbow joint dysplasia", because they are all expressions of a malformation of the joint. Furthermore, they all have similar consequences for the joint: inflammation and arthrosis. Also, common to all forms is that they are not "curable". This means that an affected joint will always remain diseased, even if adequate therapy can usually improve the lameness and reduce the painfulness.
Mostly owners present an affected animal because of a lameness of the forelimbs or for the ED breeding examination, which is mandatory for some breeding associations. Sometimes the diagnosis is made as an incidental finding. X-rays are required to make the diagnosis. In most cases, the diagnosis can already be made on the basis of well-situated. Exposed X-ray image. In some cases, a computer tomography is also recommended, but in most cases this is not necessary. Arthroscopy (arthroscopy of the joint) can also be part of the diagnosis. However, because of its invasiveness, it is only performed when surgical or. arthroscopic therapy is also being considered. Because arthroscopy is also an operation that is associated with (albeit small) risks for the patient.
There are different opinions about the appropriate treatment of elbow joint dysplasia. On the one hand, the treatment depends on the manifestation of the disease. IPA is treated differently than OCD. This again different from a FCP. On the other hand, the decision depends on the degree of the dog's symptoms and the type and degree of radiographic findings. Basically, one is faced with the decision whether to perform a surgical or a non-surgical treatment. No matter what is done – the arthrosis of the joint cannot be prevented by any currently available therapy procedure, because no "healthy" joints can be made from affected joints. In the case of OCD and IPA, surgery is almost always chosen. The isolated proces anconeus is either removed or (in young dogs with otherwise only minor joint changes) screwed on. OCD can be operated on in a number of ways, but currently the most common procedure is to resurface the defect so that a "replacement cartilage" can be formed. This is not as good as the original cartilage in terms of its properties, but it is still better than the exposed bone. Usually the operation can be performed minimally invasive via arthroscopy (joint endoscopy). FCP is the most difficult to decide whether to proceed surgically or conservatively. Many dogs walk very well despite FCP and despite relatively clear changes in the radiographs. It is controversial whether surgery is really necessary in dogs that only show episodes of lameness now and then or only lame a few steps after standing up. A lameness-free dog will not walk better after surgery, there is even a risk of worsening. The arthrosis will develop despite the operation. It has not yet been proven by scientific research that in very mild cases surgery really brings decisive benefits to the animal. Therefore, in animals without lameness, we usually do not advise surgery. However, in case of deterioration or in animals with significant lameness, surgery should be performed. In most cases, an FCP can be operated on well via arthroscopy. The damaged articular process is removed, and any exposed bone fragments are also removed. Although this does not restore the joint surface. But the inflammation and thus the irritation of the joint as well as the friction between the bones will be reduced, which usually leads to a significant reduction of pain and improvement of the gait pattern.
In dogs that have already developed severe arthritis of the joint due to the disease, the lameness is often no longer caused by the FCP itself, but by the arthritis. In some cases, a significant reduction of lameness is achieved directly after arthroscopy. However, this improvement is almost always of relatively short duration. Probably the short-term improvement comes from the joint lavage associated with arthroscopy. The removal of free bone-cartilage fragments from the joint probably also plays a role in the short-term success of arthroscopy in severely osteoarthritic patients. However, the arthrosis is not eliminated in the operation. Quickly leads to lameness again.