Elbow Dysplasia (ED)

Elbow Dysplasia (ED)

TABLE OF CONTENTS

What is Elbow Dysplasia (ED) ?

Elbow Dysplasia (ED) is essentially the abnormal conformation of the elbow joint and is an umbrella term for the pathology seen in a number of specific abnormalities that affect different sites within the elbow joint.

These include; Ununited Anconeal Process (UAP), Fragmented Coronoid Process (FCP) and Osteochondritis Dissecans (OCD).

The word โ€œdysplasiaโ€ means โ€œabnormal developmentโ€.

Canine ED is most commonly seen in young, large to giant pure breeds of dogs, typically 6-9 months old. This appears to be primarily genetically determined, however many environmental factors influence the disease process.

ED is a common cause of forelimb lameness in the dog and often clinically significant in skeletally immature dogs.

Canine ED is a growth disease and has a genetic trait as well as being influenced by environmental factors, so is multi-factorial in nature.

The elbow joint consists of 3 different articulations; the humeroradial, humeroulnar + radioulnar joints.
The elbow joint consists of 3 different articulations; the humeroradial, humeroulnar + radioulnar joints.

Remember this is the skeleton and there are all the soft tissue structures around it.
Remember this is the skeleton and there are all the soft tissue structures around it.

Breeds prone to ED

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ED mainly affects large to giant pure breeds and cross breeds. It has also been seen in some smaller breeds like Pomeranians and Shelties.

Breed examples prone to ED include;

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  • Irish Wolfhound
  • Large Munsterlander
  • Mastiff
  • Newfoundland
  • Golden Retriever
  • Rottweiler
  • St Bernard

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Pathogenesis

The elbow joint is a complex structure as it involves the articulation of three bones, the humerus, radius and ulna. The elbow is a joint of tight fit and if these bones are not congruent and do not fit together perfectly due to abnormal development, the consequence is an abnormal concentration of forces on a specific region of the elbow joint.

This incongruence comes with serious consequences, as around two thirds of the dog's mass goes through the thoracic limbs in a balanced stance, so can lead to pain and lameness.

Lateral Aspect of Left Elbow Joint.
Lateral Aspect of Left Elbow Joint.

Key;

FCP - Fragmented Coronoid Process

OCD - Osteochondritis Dessicans

UAP - Ununited Anconeal Process

Cranial View of Elbow Joint Anatomy.
Cranial View of Elbow Joint Anatomy.

Canine Elbow Joint Anatomy Related to ED.
Canine Elbow Joint Anatomy Related to ED.

Predisposing factors which decrease elbow joint congruity

These may include;

  • Genetic link
  • Overfeeding is associated with ED, due to it's impact on growth rate and obesity
  • Over exercising resulting in additional forces through the elbow during the growth period

Primary Pathology

ED is a term used to describe the primary pathology which is usually a failure of endochondral ossification and is evident in 3 different ways;

  1. Fragmentation of the Coronoid Process (FCP) is the most common finding in breeds diagnosed with ED. The pathology involves concentrations of abnormal forces on a part of the joint called the coronoid process of the ulna. These abnormal forces cause microscopic stress fractures (microfractures) within this process, resulting in pain and lameness. In many dogs, either a small portion of the process or the entire process, will separate from the remaining bone.
  2. Osteochondritis Dessicans (OCD) is much rarer than FCP, but affects similar breeds. This condition develops due to the humeral condyle cartilage failing to turn into bone, which results in an area of thickened, weakend cartilage which may become loose, forming a flap. e an The surface of the joint (cartilage) fails to convert into bone. This results in an area of thickened cartilage that is weak and may become loose, forming a flap.
  3. Ununited Anconeal Process (UAP). This presents as an elbow effusion and is often bilateral, with many dogs experiencing concurrent FCP and UAP. The anconeal process develops a separate centre of ossification but this physis should fuse within 20 weeks of age. Failure of fusion may be caused by;
  • Relative shortening of the ulna
  • Relative overgrowth of the radius
  • Abnormal development of the semiluna notch which results in abnormal contact between the anconeal process and the humeral condyle

Radiograph of the Canine Elbow Joint with ED.
Radiograph of the Canine Elbow Joint with ED.

The German Shepherd Dog (GSD) is predisposed to UAP.

Clinical Signs

Lameness is the clinical sign seen in dogs, aged between 4 to 9 months old. ED is bilateral in 40 to 50% of cases. The pattern of lameness is similar for all three conditions and the gradual onset of lameness is often intermittent in nature, being most obvious after exercise or after rest following exercise.

  • Pain
  • Painful elbow on range of motion (ROM)
  • Reduced ROM in elbow especially flexion
  • Crepitus
  • Thoracic limb lameness
  • Stiffness on rising
  • Exercise intolerance
  • Difficulty getting up or lying down
  • Difficulty descending stairs / slopes
  • Thoracic limb gait abnormality especially if bilateral, will be a short stilted gait
  • Flicking carpi whilst walking
  • Muscle atrophy of forelimb musculature

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Elbow Dysplasia is typically found in large to giant breed dogs and clinical signs start between the ages of 4 to 8 months, with males being twice as affected as females. ED commonly affects both elbows (bilateral) and is gradual in onset, with lameness seen following rest or exercise.

Elbow Dysplasia often affects both elbows, resulting in these dogs not having a limp, but moving with an unusual โ€œpaddlingโ€ gait.

Diagnostic Tests

  • Radiography (x-rays); is an imaging technique using X-rays, gamma rays, or similar ionising radiation and non-ionising radiation to view the internal form of an object
  • Computed Tomography (CT); is a medical imaging procedure that uses computer-processed combinations of many X-ray measurements taken from different angles to produce cross-sectional images (virtual "slices") of specific areas of a scanned object
  • Arthroscopy; or โ€œkey hole surgeryโ€ is also a very reliable method for identifying elbow dysplasia and it also enables minimally invasive surgery to be performed where indicated

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Arthroscopic View of Elbow Joint with ED.
Arthroscopic View of Elbow Joint with ED.

ED Treatment + Management

Treatment options from a Veterinary Surgeon's perspective are conservative (rest + pharmacological intervention) or surgical. There is now advancements in stem cell treatment by Veterinary Surgeons, which are achieving very good results, but is not currently used universally.

From a canine therapists perspective, we have a definite role to play in conservative management and pre and post surgery rehabilitation, along with maintenance plans to support the dog and owner in the long term.

FCP Treatment Options

FCP is the most common elbow condition in dogs with ED. Treatment options include;

  1. Conservative management.
  2. Surgical intervention.

Prognosis after surgery is guarded and studies have shown the dog will still suffer progressive OA regardless of surgical procedures. Due to this fact dogs with mild lameness or stiffness after rest, are not good candidates for surgery.

OCD Treatment Options

This is much rarer than FCP, but affects similar breeds. Surgical intervention is the preferred primary option for OCD.

UAP Treatment Options

  1. In the young dog, the primary option is surgical intervention.
  2. If it presents in the adult dog, then conservative management (rest + NSAIDs) is preferred.

Occasionally dogs with a UAP present for the first time as adults, with an acute onset of thoracic limb lameness. Radiographs will evidence a UAP and secondary osteoarthritis (OA). The UAP in these dogs has been an asymptomatic problem, exacerbated by recent trauma. Conservative management will usually resolve this lameness and the UAP is best left in situ if possible.

Adult dogs experiencing their first acute onset of thoracic limb lameness due to a UAP are definitely not good surgical candidates. As outcomes post operatively have very poor results in this population.

Conservative (non-surgical)

Young dogs with ED should be encouraged to appropriately exercise to reduce abnormal forces through their elbow joint, therefore improving their joint function and general mobility.

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Clinical Tip: Reducing the forces through the dog's elbow joint is important. Limiting free running, jumping and use of stairs while the dog is growing would be prudent and highly beneficial.

Important conservative treatments embracing a multimodal approach;

  • Physiotherapy
  • Hydrotherapy
  • Pain management
  • Exercise modification
  • Bodyweight control + monitoring
  • Nutritionally balanced diet
Integrated Physiotherapy & Hydrotherapy Treatment Techniques.
Integrated Physiotherapy & Hydrotherapy Treatment Techniques.

Intermediate goals of conservative treatment;

  • Manage / control PAIN
  • Minimise joint damage and promote repair
  • Minimise joint incongruency
  • Minimise formation of osteoarthritis (OA)
  • Promote fibrous and muscular strengthening
  • Optimise joint function and fore quarter stability

For each dog their SMART goal setting (short, mid + long term) will respond to their assessment findings and specific prioritised problem list. Every case is different!

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S.M.A.R.T - S = Specific, M = Measurable, A = Achievable, R = Relevant, T = Timely

Preventative Measures

Minimising joint pain is the most important factor when it comes to the conservative management of canine elbow dysplasia. These overlap with conservative treatment approaches and include;

  • Dietary management
  • Exercise management
  • Population screening

As the genetic make up of the dog is the major influence on the cause of ED, the disease can be controlled by minimising the problem genes in the canine population. This means selecting sires and dams with the best genetic makeup.

An elbow score is a measure of evidence of elbow dysplasia present. Scores from each elbow are taken and the highest score of the two elbows is taken as the score for that dog.

Scores range from 0 to 3, with the lower the score the better. The advice to breeders is to ideally breed only from dogs with scores below the breed average.

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The Elbow Dysplasia Scheme was established by BVA and the Kennel Club in 1998 to reduce the incidence and severity of the condition. ED can have serious effects on the health, behaviour and welfare of dogs. The scheme uses X-rays to screen for signs of abnormalities (irregular or poorly shaped elbow joints) caused by elbow dysplasia. X-rays are reviewed and scored by BVA-appointed expert Veterinary Surgeons.

Dog's must be at least 1 year old to have X-rays taken and scored, however there is no upper age limit.

Surgical

UAP Surgical Approaches

Arthroscopic Fragment Removal; if the CT scan and arthroscopy have shown no evidence of current elbow incongruity or radio-ulnar conflict and the diagnosis is confined to an isolated fragment of the coronoid process of the ulna, this fragment can be removed. Research shows soundness is expected in only 50% of dogs and around 25% do not improve significantly.

Proximal Ulnar Osteotomy (PUO); This is also known as Proximal Dynamic Ulnar Osteotomy (PDUO). A surgical technique of cutting the ulna below the elbow joint is performed. This allows the proximal ulna to displace proximally and relieve the pressure between the UAP and humeral condyle. If surgery is performed early enough (before 6 months of age) then many UAPs will spontaneously reunite.

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PUO is not a benign procedure as the osteotomy is very painful for 6 - 10 weeks and heals slowly.

Proximal Abducting Ulnar (PAUL) Osteotomy; an ulnar osteotomy is performed via a caudo-lateral approach and is secured with a plate and screws to stabilise the bone while it heals in the new position. This is also referred to as a load-altering osteotomy. Studies suggest this may be the best option.

FCP Surgical Approaches

Medial Arthrotomy; removal of loose fragments, or curettage of cartilage.

Medial Arthrotomy with concurrent PUO; to alleviate the abnormal pressure between the humeral condyle and the medial coronoid region.

Arthroscopy (medial portals); with osteochondral debridement and lavage, with or without PUO.

Early surgical intervention is considered to have a much better prognosis.

Prognosis (Px) following surgery is guarded and unpredictable. Dogs will suffer OA regardless of surgical treatment and studies show little clear benefit following surgery.

Dogs with relatively mild lameness or stiffness after rest are NOT good surgical candidates, whereas dogs that suffer progressive lameness during exercise are generally better candidates.

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Surgical treatment of chronic disease is usually disappointing.

OCD Surgical Approaches

OCD is much less common than FCP, but affects similar breeds;

  1. Removal of the OCD flap via arthrotomy or arthroscopy.
  2. Conservative (surgery is generally preferred for OCD).

Other Surgical Options

Subtotal Coronoid Ostectomy (SCO); in elbows where there is diffuse stress fracturing of the coronoid process of the ulna, the majority of the process should be removed using arthroscopy.

Total Elbow Replacement (TER); elbow osteoarthritis can be extremely severe in some cases, with little or no healthy cartilage remaining. TER is used as a salvage procedure, when other treatments will be ineffective. The entire elbow joint surface is replaced with a custom elbow prostheses.

ED is the commonest cause of forelimb lameness in young, large to giant breed dogs. The long-term prognosis is dependent on the degree of OA in the elbow joint.

References & Useful Links

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