ED / HD
|Elbow Dysplasia|UAP|OCD|FMCP|Incongruity|Treatment|
|Hip Dysplasia|Treatment|
Elbow Dysplasia (ED)
The elbow joint is composed of three bones (radius, ulna,
and humerus) which must all grow together and fit perfectly.
The radius is the main weightbearing bone. The ulna serves
more as a lever arm for the extensor muscles of the elbow
joint. The normal elbow joint is characterized by a smooth
transition from the ulnar articular (joint) surface to the
radial surface. The medial coronoid process of the ulna
sits level with or slightly below the surface of the radius.
The most common cause of elbow pain and forelimb lameness
in young large breed dogs is elbow dysplasia. Elbow dysplasia
is a term used to describe 4 different developmental abnormalities
within the elbow joint. They are:
- Ununited Anconeal Process (UAP)
- Osteochondritis (OCD)
- Fragmented Medial Coronoid Process (FMCP)
- Incongruity
Elbow Dysplasia is a polygenic condition (more than one
gene is necessary to cause the disease), although it is
not currently known how many or which genes are responsible.
Environmental factors such as over-feeding, which causes
fast weight-gain and growth, can also affect the development
of this condition in dogs that are genetically predisposed
to it.
Ununited anconeal process (UAP)
Ununited anconeal process is a condition
in which a fragment of bone on the back side of the joint
has failed to unite with the ulna bone during growth. Normally
this bony process fuses with the ulna bone by 20 weeks of
age
Osteochondrosis Dissecans (OCD)
Osteochondritis Dissecans is a disease that
occurs when bone is growing. In young dogs, the bones have
growth plates made of cartilage in areas where growth will
occur. Bone grows by changing its cartilage growth centers
into bone, layer by layer. If this process is disturbed, the
cartilage may not calcify properly, it just grows thicker.
This thick spot of cartilage doesn’t receive a proper
blood supply so it dies and cracks form. This leaves a defect
in the cartilage covering the end of the bone. If the growth
plate for the anconeal process or the coronoid process doesn’t
calcify properly, the little bony projections won’t
attach to the ulna. A problem in any of these areas means
that the elbow joint won’t fit together properly and
will be unstable, this can cause lameness and eventually arthritis.
Fragmented medial coronoid process (FMCP)
Fragmented medial coronoid process is a
condition in which a small piece of bone on the inner side
of the joint has broken off of the ulna bone. This piece of
bone irritates the lining of the joint and grinds off the
cartilage of the adjacent humerus (similar to having a pebble
in your shoe).
Incongruity
In a dysplastic elbow, the medial coronoid process and
the edge of the ulnar surface lie above the level of the
adjoining radius, creating a step between the radius and
ulna and causing incongruity of the joint. This incongruity
alone is often a source of pain and lameness (as with walking
around in a shoe that doesn’t fit). The height of
the step may vary from barely noticeable to a distance of
4 mm. When this occurs, the weightbearing force on the ulna
is increased, resulting in excessive pressure on the medial
coronoid process. This leads to fragmentation of the coronoid.
This usually occurs between 5 and 7 months of age. The fragment(s)
is(are) often the size of a rice grain, or larger. Incomplete
fragmentation, in the form of cracks or fissures, can also
occur. A superficial to deeply grooved "kissing lesion"
is often present on the humeral articular surface opposite
the fragment. A cartilage flap or OCD (osteochondritis dissecans)
lesion may also be present. Secondary arthritis becomes
evident at 6-7 months. Compensatory adjustments during growth
may occur in some dogs, tending to minimize unequal growth
rates between the three bones and moving the ulna distally
to better conform to the radius. However, excessive force
is then placed on the anconeal process at the top of the
ulnar articular surface. This force will cause a failure
of ossification, leading to an ununited anconeal process.
Treatment
Treatment of elbow dysplasia is often a combination of
medical and surgical management. The objectives of therapy
are to relieve pain and maintain limb function, as well
as to continue the dog at as normal an activity level activity
level as possible. Surgical removal of the fragments is
recommended before the development of severe arthritis occurs.
While the choice of surgical technique (arthroscopy or traditional
surgery) may vary, the results with both are similar. Unfortunately,
this disease is progressive, improvement is expected, but
not normality. Medical therapy consists of weight control,
moderate exercise and antiinflammatory medications. Each
case is evaluated for the degree of discomfort and arthritic
change before a final treatment choice is elected.
All immature dogs with fragmentation of the coronoid, OCD,
or an ununited anconeal process are surgical candidates.
Recent studies suggest that, if an ununited anconeal process
is detected early enough, an ulnar osteotomy (cutting the
ulna) to relieve the stress may allow the process to unite
in a normal fashion. Dogs with mild to moderate incongruity
and minimal arthritis have the best prognosis. Even dogs
with marked incongruity and large lesions benefit from surgery
due to the decrease in pain.
Source: Southern California Veterinary Referral
Group, Daniel A. Degner, Jennifer Freeman, Orthopedic Foundation
for Animals
Hip Dysplasia
Hip dysplasia literally means an abnormality
in the development of the hip joint. It is characterized by
a shallow acetabulum (the "cup" of the hip joint)
and changes in the shape of the femoral head (the "ball"
of the hip joint). These changes may occur due to excessive
laxity in the hip joint. Hip dysplasia can exist with or without
clinical signs. When dogs exhibit clinical signs of this problem
they usually are lame on one or both rear limbs. Severe arthritis
can develop as a result of the malformation of the hip joint
and this results in pain as the disease progresses. Many young
dogs exhibit pain during or shortly after the growth period,
often before arthritic changes appear to be present. It is
not unusual for this pain to appear to disappear for several
years and then to return when arthritic changes become obvious.
Dogs with hip dysplasia appear to be born
with normal hips and then to develop the disease later. This
has led to a lot of speculation as to the contributing factors
which may be involved with this disease. This is an inherited
condition, but not all dogs with the genetic tendency will
develop clinical signs and the degree of hip dysplasia which
develops does not always seem to correlate well with expectations
based on the parent's condition. Multiple genetic factors
are involved and environmental factors also play a role in
determining the degree of hip dysplasia. Dogs with no genetic
predisposition do not develop hip dysplasia.
Treatment
Treatment of hip dysplasia can be conservative
or surgical, The objectives of conservative therapy are to
relieve pain and maintain limb function, as well as to continue
the dog in as normal a level of activity as possible. Conservative
therapy consists of weight control, moderate exercise and
analgesics (pain relief medication). The most important element
will always be the Maintenance of Muscular Support. Muscle
is built by walking, jogging, and swimming, which do not stress
the joint. Acrobatics (playing frisbee, jumping, etc.) should
be avoided, as they place unnecessary pressure on the joint.
A newer medical approach to the treatment
of degenerative arthritis secondary to hip dysplasia involves
the use of products called polysulfated glycosaminoglycans
or PSGAGs. PSGAGs are naturally occurring components of the
joint cartilage and increase joint fluid production. Although
results are preliminary and no controlled studies in dogs
have been performed, there have been several reported successes
with these compounds in selected cases.
When should a patient receive conservative
management as opposed to specific surgical treatment? The
answer depends on the age of the dog, the intended use of
the dog, the degree of arthritis, the severity of the lameness
and the financial capability of the owner. Approximately 50-60%
of the patients may respond to conservative therapy over a
long period of time. The remaining 40-50% will require surgical
treatment. Unfortunately, there is no way to predict into
which category any one particular dog will fall.
Three surgical procedures are currently used
in the treatment of hip dysplasia. In young patients with
minimal evidence of arthritis, a stabilizing reconstruction
of the hip joint is recommended. This involves reconstructing
the joint congruency and stopping the subluxation and laxity
that lead to severe arthritis. This technique centers around
the Triple Pelvic Osteotomy. It has been established as a
reliable, predictable mode of treatment in those cases which
meet the case selection criteria.
Once the patient (usually adult) has radiographic
evidence of degenerative arthritis, it is no longer a candidate
for a triple pelvic osteotomy procedure. Over time, many of
these dogs will become less responsive to analgesic medications
and surgical therapy should be considered. There are two procedures
available.
1) Removal of the femoral head and neck (excision
arthroplasty, femoral head ostectomy, FHO)
2) Total hip replacement
Femoral head excision works well for dogs
under 30 lbs and those with unilateral dysplasia. It is less
satisfactory for dogs over 50 lbs, particularly when performed
bilaterally. This is a salvage procedure for those owners
who cannot afford the cost of a total hip replacement, but
need an alternative to constant medication and debilitating
pain.
Introduced in 1976, the Total Hip Replacement
has become the only treatment available that provides normal
hip joint function once advanced arthritis is present. With
this technique, the femoral head and neck are replaced with
a cobalt chrome, or titanium, component and the acetabulum
is replaced with a plastic cup prosthesis. A five year follow
up study of 221 total hip replacements revealed an overall
success rate of 91%. Total hip replacement can be done on
both hips, although many dogs (80-90%) do very well with one
side replaced.
3) Pectinectomy involves cutting the tendonous
attachment of the "groin" muscle known as the Pectineus.
This relieves the immediate tension on the hip joint and tends
to diminish pain
Source: Dr Michael Richards, Southern California
Veterinary Referral Group |Elbow
Dysplasia|UAP|OCD|FMCP|Incongruity|Treatment|
|Hip Dysplasia|Treatment|
|
