Elbow Dysplasia
Elbow dysplasia is a term used to describe a disorder in growing bone. It means that one or more of the following conditions are present:
Normal bone growth consists of the fusion of many bones into one bone. Many bones in a newborn puppy are not just one piece of bone, but several different pieces of bone with cartilage in-between. This is especially true of long bones of the limbs. As the puppy grows the cartilage changes into bone and the several pieces of a bone fuse together forming one entire bone. For instance, the ulna, a bone in the forearm starts out as 4 pieces of bone that eventually fuse into one.
In elbow dysplasia, the cartilage between the bony areas fails
to turn into bone and often becomes thickened. The cause of this
may include genetic factors, trauma and nutrition. The signs of
this abnormal bone growth usually develop between 6 and 9 months
of age, and generally appear as lameness. Elbow dysplasia is more
common in rapidly growing, large breed puppies.
In the healthy dog, the elbow joint itself is fairly complicated.
The elbow of the dog corresponds to ours anatomically but rests
relatively closer to the chest wall then it does in man. The bones
that form the joint are the humerus from above the ulna and radius
from below. The lower end of the humerus has two rounded knobs
(the lateral and medial condyles) on it with a hole between that
extends completely through the bone (the supratrochlear foramen).
The radius and ulna bones basically act as one bone as they are
held tightly together by several ligaments. They move together
at all times. The upper end of the ulna has a hook-like process
that fits neatly into the supratrochlear foramen of the humerus
and a curved ridge called the trochlear notch that fits against
and rotates between the medial and lateral condyles. At the base
of this notch and on either side of it are the medial and lateral
coronoid processes that the condyles of the humerus rest on, therefore
supporting the weight of the dog. Finally there is the upper end
of the radius that also lies between the coronoid processes of
the ulna and it also helps support the weight of the animal as
it is transmitted down through the humerus. In the normal dog,
all of these surfaces that rub each other are perfectly smooth.
They are constantly lubricated by the joint fluid that is contained
by the capsule that surrounds the joint.
The elbow is a fairly complicated joint and anything that alters
any of the bones or their articular surfaces will affect the ability
of the animal to use the leg correctly. There are three common
areas of dysplasia in the elbow. "Elbow dysplasia" is
a term used to describe a condition in which one or more of these
three areas are affected Actually, most cases will have at least
two if not three occurring at the same time. A case may start
out with just one, but as time passes the other changes may occur
as a result of the first, or develop independently from genetic
programming. There is some controversy today as to which of these
changes is most important or if a particular one is an initiator
of the syndrome.
Researchers and clinicians believe that the first change or degeneration in elbow dysplasia is "fragmentation of the medial coronoid process". The coronoid processes of the ulna articulate with the condyles of the humerus and also bear much of the weight of the dog. Fragmentation means that the bone in this area of the ulna starts breaking up or degenerating, exposing the underlying tissues of the bone. This occurs very early in the life of the dog, often times before six months of age. We see it mostly in the larger breeds. This is thought to be genetic.
The second change is "ununited anconeal process". Generally by 20-24 weeks of age the anconeal process should have fused with the ulna. In UAP, the hook, or anconeal process, never attaches correctly to the rest of the ulna as the puppy is developing, but rather floats loose. It is held close to where it should be by ligaments between it and other portions of the bone but it is not solid enough to remain exactly where it should. This leads to instability, preventing the humerus and ulna from interacting correctly. Additionally, the loose anconeal process is often caught abnormally between the ends of the ulna and humerus thus irritating and bruising the articular surfaces. Ununited anconeal is commonly found by itself with the elbow dysplasia syndrome. However, when it is discovered in larger breeds, it is almost always part of the elbow dysplasia syndrome and most of these dogs will also have the fragmentation disorder of the medial coronoid process.
The last of the three elbow disorders is osteochondritis dissecans of the medial condyle of the humerus. Osteochondritis dissecans is also a common problem of the shoulder joint in young, rapidly growing larger breeds. Most believe that osteochondritis of the medial condyle of the humerus may be secondary or caused by the fragmentation of the bone of the medial coronoid process on the ulna. These two affected areas come together and rest on each other at this site and the first lesion may therefore precipitate the other. In all joints where different bones come together and articulate against each other, the surface of the bone is covered with cartilage. It acts as a cushion, protecting the underlying bone from irritation or damage as the two bones come together. With OCD, a portion of that cartilage loosens from the underlying bone. It may break loose and float free in the joint or remain partially attached to the bone like a flap. In either case this is an extremely painful situation as the lower bony layers are exposed to trauma and the joint fluid.
Patients with elbow dysplasia will usually display an obvious
limp, may hold the leg out from the body while walking, or even
attempt to carry the front leg completely, putting no weight on
it at all. Signs may be noted as early as four months of age.
Many affected animals will go through a period between six and
about twelve months of age, during which the clinical signs will
be the worst. After this period, most will show some signs occasionally
but they will not be as severe. As these dogs continue to mature,
there will probably be permanent arthritic changes occurring in
the joint. This will cause many obvious problems and it may become
necessary to utilize oral or injectable medications to make the
animal more comfortable. Elbow dysplasia is therefore a life long
problem for the affected animals. Some of these patients can be
helped with surgery. In some, surgery can even eliminate the problem
totally.
Most affected dogs will have two, and most probably all three
of the elbow dysplasia disorders present at the same time. A majority
of these animals will have both their right and left elbows involved.
The symptoms of front leg lameness and pain in the elbow lead
to a diagnosis of elbow dysplasia. However, there are other conditions
that can affect the front leg of a young dog that will mimic the
signs of elbow dysplasia very closely. Therefore, it is necessary
to take x-rays of the elbow(s) to verify the diagnosis.
Treatment of elbow dysplasia varies with what abnormalities are
present. Fragmented coronoid process and OCD are often treated
medically, without surgery. The young dog is placed on a regular
low-impact exercise program (swimming is often preferred). Depending
on the severity of the condition however, surgery may be performed
to remove the fragmented process or cartilage flap.
United anconeal process is usually treated with surgery in which the ununited process is removed. In some instances, small pins or screws may be used to join the process with the rest of the ulnar bone.
Usually after the dog is 12 to 18 months of age the lameness will
have become less severe and some dogs can function very well.
The long-term prognosis (outlook) however is guarded. Usually
degenerative joint disease (arthritis) will occur as the animal
ages, regardless of the type of treatment.
Question and answer
What is elbow dysplasia ?
Elbow dysplasia is a general term for four abnormalities of the bones in the elbow that may develop in growing puppies. These abnormalities lead to the development of arthritis in the elbow. The four abnormalities are ununited anconeal process, osteochondritis dissecans (OCD), fragmented medial coronoid process, and lack of alignment of the bones (incongruity). The abnormalities may develop individually or in any combination. These abnormalities may affect one or both elbows. Dogs commonly have problems in both elbows.
The causes of elbow dysplasia include the following:
What are the signs of elbow dysplasia ?
Dogs with elbow dysplasia are usually taken to the veterinarian for an evaluation by 8 to12 months of age because of forelimb lameness. However, it is common for clinical signs not to be observed by guardians until the dog is much older. The lameness generally progresses from stiffness that is initially seen only after the dog rests to intermittent or persistent lameness that worsens with exercise. Dogs with elbow dysplasia often have difficulty rising from a lying down position, a stiff gait because of reluctance to bend the elbow joint, and swelling of the joint, and they demonstrate pain when this joint is manipulated.
How is elbow dysplasia diagnosed ?
Your veterinarian may suspect elbow dysplasia after initial
examination of your pet. Radiographs
(X-rays) are necessary to confirm the presence of disease and
to potentially identify the type of
dysplasia. When clinical signs are mild or when radiographic changes
are minimal, your
veterinarian may recommend taking additional radiographs in 4
to 8 weeks or performing more
advanced diagnostic tests such as CT (computed tomography) scan,
MRI (magnetic resonance
imaging), or linear tomography.
How is elbow dysplasia treated ?
While somewhat controversial, surgery is considered the treatment
of choice for dogs with elbow
dysplasia. The surgical technique varies depending on the type
of dysplasia. Your veterinarian will
discuss the various options with you along with advantages and
disadvantages of each technique.
Recently, arthroscopy has been shown to be an excellent surgical
tool in the diagnosis and
treatment of elbow dysplasia in dogs. Medical treatment in the
form of administration of
anti-inflammatory drugs and cartilage-protecting drugs is often
prescribed as an alternative to
surgery and as a long-term follow-up to surgery.
What is the prognosis for animals with elbow dysplasia ?
The prognosis is considered fair to good for all forms of elbow
dysplasia. Clinical signs related to
the arthritis are commonly seen even after surgical treatment.
Stiffness and soreness after vigorous
activity should be expected. Early surgical intervention along
with long-term medical therapy may
minimize the progression of arthritis. Animals diagnosed with
elbow dysplasia should not be bred
because of the concern that this is an hereditary condition. A
dam/sire breeding that results in
offspring with elbow dysplasia should not be repeated.
The majority of the information
in this page is has been taken from VetMedCenter.com. For further information about this
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