Osteoarthritis: An Important Disease?

What Is Osteoarthritis?

Osteoarthritis (OA) is a disorder of diarthrodial joints characterized by deterioration of the articular cartilage, osteophyte formation and bone remodeling, changes in the periarticular tissues (synovium, joint capsule) and a low-grade inflammation of the synovial fluid. This condition invariably leads to clinical signs of pain and loss of function (disability).

The definition of OA has changed through the years. Here is one of the most recent reaching consensus: “OA diseases are a result of both mechanical and biological events that destabilize the normal coupling of degradation and synthesis of articular chondrocytes and extracellular matrix, and subchondral bone. Although they may be initiated by multiple factors, including genetic, developmental, metabolic and traumatic, OA diseases involve all the tissues in the diarthrodial joint. … When clinically evident. OA diseases are characterized by joint pain, tenderness, limitation of movement, crepitus, occasional effusion and variable degrees of inflammation without systemic effects.”

Sharma L and Kapoor D. Epidemiology of osteoarthritis. In: Moskowitz et al., eds. Osteoarthritis. 4th edition. Lippincott Williams & Wilkins; 2007: p3

Osteoarthritis has many forms: the most common one observed in veterinary medicine is degenerative joint disease. Degenerative joint disease leads to structural and functional changes.

Osteoarthritis can be qualified as either primary or secondary.

Primary Osteoarthritis

Rare in small animal practice
Abnormal cartilage with normal forces
Primary cartilage disease
Osteochondrosis/OCD

Secondary Osteoarthritis

The most frequent in veterinary medicine
Normal cartilage with abnormal forces
Repeated trauma/athletic trauma
Loss of cartilage

Osteochondrosis/OCD

Instability
Rupture of the cranial cruciate ligament
Suboptimal joint congruence
Canine hip dysplasia
Elbow dysplasia
Articular fractures
Inflammatory/immune mediated
Prevalence in our patients

Canine

Is it frequent?

It is estimated that osteoarthritis affects 1 out of 5 dogs over the age of 1 year in North America.
19 million dogs afflicted by OA in North America
Reported that 50% of large breed dogs over 6 years of age have radiographic signs of OA
Are breeds at risk?

Mixed breed dogs and dogs of any breed, size weight and age can be afflicted by osteoarthritis.
The incidence increases with age
The incidence increases with the size of the dog
Breed predispositions
Genetics!

Feline

Several studies report the incidence of radiographic osteoarthritis in cats
Reported between 33,9 and 92%
The incidence is correlated with age
Should we address it?
When we denote lameness clinically, what does it mean?
How significant is it?
Classification/quantification of lameness
• Subjective
• Semi-objective
• Objective

Subjective

Numerical rating scale
NRS: from 1 to 4–5
Visual analog scale
VAS: from 0 to 100
Poor correlation between scales and objective measures…

Semi-Objective

WOMAC
Humans
Cincinnati orthopaedic disease index
CODI, Gingerich
Used by our group and Lascelles
Canine brief pain inventory
CBPI, validated by Cimino-Brown

Objective

Kinetics: Forces
The branch of mechanics that deals with the actions of forces in producing or changing the motion of masses

Biomechanics: study of forces generated by the musculoskeletal system

Ground reaction forces (GRF)

Peak vertical force (PVF) is the most commonly used
In Newtons (weight x acceleration)
Standardized as % in body weight
Gold standard

Kinematics: Motion
The branch of mechanics that deals with pure motion without reference with the forces involved during locomotion

Biomechanics: study of motion (angulation and rotation) generated by the musculoskeletal system

Activity
Podometer
3D actimetry

Using objective measures, how does it reflect the affliction of our patients?
In the normal patient, at a trot on a hind limb:
Weight bearing is around 72% BW
Stance: 20% BW
Walk: 54% BW

How much is the decrease in weight bearing in afflicted dogs?

We include dogs that have BW <64% BW
Madore et al. VCOT 2007
Using this cut off, accuracy >95% to detect lameness (personal communication)
When we observe lameness clinically, dogs usually decrease their weight bearing on the affected limb by at least 8% of their body weight
On a 35-kg dog, this represents 2,8 kg
Imagine for a 70-kg Human, it represents 5,6kg

Conclusion

Osteoarthritis is an important disease that affects the quality of life of our canine patients. When lameness is observed, we must thrive to alleviate the clinical signs associated with OA.

Multimodal Approach to Osteoarthritis

When faced with a patient that shows signs of osteoarthritis, the clinician must establish a therapeutic plan. First it is imperative that a correct diagnosis has been given:
it frequently occurs that a patient is considered “arthritic” when it is not. The therapeutic plan in this case just doesn’t work!

Evaluation of a Patient Afflicted by Osteoarthritis

Lameness is defined as an alteration in gait. This alteration can originate from 3 sources:

• Orthopedic
• Neurologic
• Metabolic

The complete lameness examination must comprise:

History/anamnesis

General health? PU/PD, vomiting/diarrhea, cough?
When? How? Since when? Exacerbation? Response to treatment?

Physical examination

Thorough PE to determine general health, anemia, cardiac disease, abdominal mass, etc…
Visual gait analysis

Determine if patient is lame or not
Shorter stride, stiffness
Which limb? Beware of owners…
Walk, trot, sit, down, up

Orthopedic examination

Muscle atrophy, pain, crepitus, effusion, fibrosis, decreased range of motion, instability

Partial neurological examination

Ataxia, proprioception, weakness, reflexes

Once completed, establish a problem list, list of differential diagnoses, a diagnostic plan, then confirm diagnosis. With the confirmation of symptomatic OA, a therapeutic plan can be proposed to the owners.

Correlation between the lameness, physical/orthopedic examination findings and the diagnostic results.

No correlation between the severity of radiographic lesions and the degree of lameness.

Multimodal Management of OA

The multimodal management of OA consists of the following:

• Surgically treating the primary cause if possible OA is secondary

Primary cause can sometimes be surgically addressed
Rupture of the cranial cruciate ligament

• Reducing the patient’s weight

Weight reduction is imperative
Avoid weight gain…

• Using adapted activity combined with physical therapy

Passive
Active

• Using therapeutic nutrition

Polyunsaturated fatty acids (Ω-3s)
Chondromodulators/Nutraceuticals, etc..
PSGAGs, glucosamine, chondroitin sulfate, QEVA, green lipped mussels (GLM)
Antioxidants
Vitamins

• Using pharmacological therapy

NSAIDs are the cornerstone of treatment of OA
Anti-inflammatory and analgesic effects
Corticosteroids
Opioids
NSSRI- SSRI Non-selective/ Selective serotonin receptor inhibitor
Tramadol
NMDA-antagonists