Lecture 2: Clinical Manifestations of and Diagnostic Tests for Joint Disorders

animals with joint disease commonly present with

a history of lameness or gait abnormality

lameness may involve

one joint/limb (typically traumatic or developmental) or multiple joints/limbs (degenerative or inflammatory)

disorders affecting the joints can either be

non-inflammatory or inflammatory

non-inflammatory disorders have a lot of

monocytes

inflammatory disorders have a lot of

neutrophils

non-inflammatory joint diseases include

• developmental

• degenerative

• neoplastic

• traumatic processes

inflammatory joint diseases include

• infectious → ex. Borrelia burgdorferi

• non-infectious (immune-mediated) → erosive like Rheumatoid-like arthritis and non-erosive like IMPA, SLE

inflammatory joint disease

• very painful joints that cause shifting leg lameness or characteristic “walking on eggshells” → reluctance to exercise or move

• signs of systemic disease

• multiple joints usually affected

true or false: as many as 25% of dogs with immune-mediated polyarthritis do not have obvious joint pain or swelling.

true

degenerative non-inflammatory joint disease

• low-grade chronic discomfort

• fluctuating/intermittent lameness

• reluctance to exercise without systemic signs of illness

• multiple joints may be affected, but signs are usually consistent from day to day

• patient often “warms” out of lameness

PE for degenerative non-inflammatory joint disease

• conduct PE to localize a region of pain or inflammation

• animal’s posture and gait

• manipulate and palpate the spine and the muscles, bones, and joints of each limb

• give equal consideration to systemic examination

DDx for pain upon palpation of bones

trauma, panosteitis, hypertrophic osteodystrophy, osteomyelitis, bone neoplasia

DDx for pain upon palpation of muscles

myositis, strain/sprain injuries

DDx for neck pain upon palpation

spinal cord or vertebral abnormalities such as IVDD, intracranial disease, meningitis, polyarthritis

DDx for spine pain upon palpation

spinal cord or vertebral abnormalities such as IVDD, diskospondylitis, intervertebral face joint inflammation

PE with decreased range of motion, crepitation and joint instability suggests

• articular damage and wear

• osteophytes

• peri-articular changes

• tendon/ligament damage

what are these showing?

effusion

what is this?

effusion

radiography for joint disease

• used for initial diagnostic evaluation when only one joint is clinically affected, or joint palpation reveals crepitation, instability or a restricted range of motion

• 2 views should be made of each affected joint

if presumed IMPA, radiographs are not recommended if the response to treatment is rapid and complete because

the only abnormalities usually observed are mild joint capsule distention and associated soft tissue swelling

radiographs from patients with infectious polyarthritis typically only demonstrate

soft tissue swelling and effusion

what is this showing?

UAP

arthrocentesis/synovial fluid analysis

• minimal risk, high diagnostic yield

• sedation for dogs, general anesthesia recommended for cats

if polyarthritis is suspected, synovial fluid should be analyzed from at least

3 to 4 joints, including at least one carpus, one hock, and one stifle

arthrocentesis/synovial fluid analysis procedure

• sterile

• only a very small amount of joint fluid is needed for determination of viscosity, estimated cell count, differential WBC count, and culture

• larger volumes are required for a cell count

what should you always do for an arthrocentesis?

aseptically prepare and wear gloves

synovial smears should be prepared immediately by

putting one drop of synovial fluid onto each slide, and a second slide is used to make the smear

normal synovial fluid

• thick, viscous fluid secreted by the synovium

• clear to slightly yellow in color

• high content of hyaluronic acid and additional molecules such as lubricin

what is the primary function of normal synovial fluid?

to lubricate articular surfaces and facilitate movement within the joint

joint fluid appearance from left to right

• normal

• non-inflammatory

• inflammatory

• septic

• hemorrhage

what is this?

synovial fluid analysis → “string effect”

components of normal synovial fluid

• no more than 3 WBCs per high-dry power (40x) field

• mixture of large and small mononuclear cells

• <10% neutrophils

• blood contamination = 1 neutrophil/500 RBCs

what is this?

non-inflammatory sample → many monocytes

what are these cells?

macrophages and monocytes

is this cytology consistent with normal, inflammatory or noninflammatory joint disease?

non-inflammatory

name a common joint disease that is consistent with this cytology?

CCL rupture

what are these cells?

neutrophils

is this cytology consistent with normal, inflammatory or noninflammatory joint disease?

inflammatory

what are two differential diagnoses for this patient based on this cytology?

immune-mediated and tick-borne/infectious

what is 1?

ragocytes

what is 2?

LE cells

other tests to rule out systemic disease

• radiographs → abdomen and thorax

• bloodwork → tick-borne disease panels, immune panels

• cultures → blood, urine, bone