Joints II Flashcards
Example of Abnormalities of Growth and Development
- Arthrogryposis
- Elbow dysplasia
- Hip dysplasia
Arthrogryposis
- Persistent congenital flexure of a joint
- Ex. flexural deformity
What are some proposed causes of arthrogryposis?
- Ingestion of poisonous plants by dame
- Genetics
- Viral infections
- Lack of in utero movement by fetus
- Disease of vertebral column
- Disease of spinal cord
- *some may be related
Elbow dysplasia
- Common cause of forelimb lameness in YOUNG, LARGE breed dogs
- Term to refer to clinical syndrome of lameness, pain and DJD with the elbow
Most accept that elbow dysplasia is an inherited disease and is most common in
- Basset hounds
- Bernese mountain dogs
- Irish wolfhounds
- Newfoundland dogs
- English mastiffs
- German shepherd dogs
- Great danes
- Golden and labrador retrievers
- Rottweilers
What are the 5 causes of elbow dysplasia?
- Ulnar trochlear notch dysplasia
- Elbow join incongruity
- Fragmentation of medial coronoid process of the ulna
- Ununited anconeal process
- Osteochonritis dissecans (OCD) of the medial askpec of the humeral condyle
*often more than one
Hip dysplasia
- Abnormal development of femoral head and acetabulum
- *most important in LARGE and GIANT breed dogs
o Does occur in medium breed dogs and other species - *underlying abnormality=biomechanical one
- *inherited, polygenic problem
- Lesions often not present at birth, but advanced by one year of age
- Mild=may not show clinical signs
Biomechanical abnormality in hip dysplasia
- There is INSUFFICIENT muscle to keep femoral head and acetabulum in close appositions
What does the insufficient muscle in hip dysplasia result in?
- Joint laxity
- Abnormal wear
- *damage to articular cartilage and other soft tissues
- Damage to hip joint is progressive and eventually causes DJD
Hip dysplasia is an inherited, polygenic problem and is influenced by
- Environmental factors (Ex. nutrition)
- Exercise
Arthritis
- Inflammation of intra-articular structures
- “inflammation of a joint”
Synovitis
- Inflammation of synovium
Capsulitis
- Inflammation of joint capsule
- *infrequently used in pathology
Classification of inflammation of joints: distribution
- Arthritis vs. polyarthritis
Classification of inflammation of joints: nature of exudate
- Serous
- Fibrinous
- Purulent or suppurative
- Fibrinopurulent
- Non-suppurative
What are the broad categories of etiologies for inflammation of joints?
- Septic (ie. Involving microorganisms)
- Non-septic
- Immune-mediated
Septic arthritis
- Microorganisms can arrive in joints by several means
- Majority are caused by bacteria (including mycoplasma)
- Fungi and viruses can also cause it
- *most common in neonatal farm animals
o Referred to as ‘joint-ill’
What are the different ways microorganisms can arrive in joints (4)?
- Direct introduction during traumatic event
- Extension from periarticular soft tissue
- Extension from bone
- Hematogenously
Non-septic arthritis
- *SEE DJD
Immune-mediate arthritis
- Describe a subgroup of non-infectious inflammatory joint diseases
- Evidence of immune system involvement through immune complexes
- Typically manifests as polyarthritis
- Rarely in dogs, even less in cats, even rarer in other species
- Ex. rheumatoid arthritis
Rheumatoid arthritis
- Type of immune mediated or autoimmune arthritis in people
- Focus of inflammation is the synovium and leads to damage of articular cartilage
Degenerative joint disease (DJD) (osteoarthritis)
- PROGRESSIVE disease of synovial joints that begins as a IRREVERSIBLE degeneration of articular cartilage
- May be accompanied by
o Changes in soft tissue
o Formation of osteophytes
o Sclerosis of subchondral bone - *may or may not be associated with clinical signs
Sclerosis
- Hardening
- In relation to bone: indicates increased DENSITY
What is the cause of DJD?
- Not fully understood
- Likely represents a common set of lesions associated with a variety of different disease processes
What might the initiation of DJD be?
- Degeneration of articular cartilage
- Inflammation of joint capsule or synovium
- Increased stiffness of subchondral bone
Regardless of initiating factors, DJD will always
- *include degeneration of articular cartilage
Where can DJD develop?
- Joints with normal cartilage followed by abnormal stresses
- Joins with abnormal cartilage following normal stresses
What can the early stages of cartilage degeneration be recognized as grossly in DJD?
- dull or rough appearance
- yellow-brown discoloration (chondromalacia)
What might DJD look like growly later on?
- Fibrillation and focal erosions of articular cartilage may develop
- With continue used: lead to EBURNATION with changes in subchondral bone
Osteochondrosis
- Disorder of physes and articular cartilage of endochondral bones of GROWING ANIMALS
- *of articular cartilage is important and relatively common in several domestic species
Osteochondrosis definition
- Focal or multifocal failure (or delay) of endochondral ossification resulting in localized thickening of hyaline cartilage
o Not as stable as bone
o May be subject to injury leading to pain and lameness
What can happen with focal disruption of endochondral ossification and centrifugal bone growth?
- Potential to alter the shape of an articular surface
- May lead to angular limb deformities
What can alteration in a joint surface lead to?
- Abnormal articulation
o Predispose joint to DJD
What can occur with osteochondrosis in some instances?
- Transverse or ‘horizonal’ clefts can develop within the foci of thickened cartilage or between thickened cartilage and underlying bone
o Creates flaps or free fragments of cartilage in the joint - *resulting lesion=osteochondritis dissecans (OCD)
What are the fragments of cartilage free in the joint called? (osteochondrosis dissecans)
- Joint mice
Where is a common site of osteochondrosis in dogs?
- Humoral head
- *typically in males of large and giant breeds
What are the predilection sites for osteochondrosis in horses?
- Lateral trochlear ridge and medial condyle of femur
- Patella
- Various sites in tarsi
What are angular limb deformity (ALD) relatively common in?
- young, growing, animals of a VARIETY of species
What can ALD’s be due to?
- Uneven growth of physis
- Irregularly shaped bones of carpal and tarsal joints
- Joint instability or laxity
- *OR combination of these lesions
What is lateral deviation of the limb distal to the abnormal physis or joint referred to as?
- Valgus deformity (‘knock kneed’)
What is medial deviation of limb distal to abnormal physis or joint referred to as?
- Varus deformity (‘bowlegged’)
What is a proliferative lesion of joints?
- Villonodular synovitis (chronic proliferative synovitis)
Villonodular synovitis (chronic proliferative synovitis)
- Proliferative and inflammatory (macrophages and lymphocytes) lesion of synovium of joints and tendon sheaths
What is a variable feature of villonodular synovitis?
- Presence of hemosiderin in some of the synovial cells
What is villonodular synovitis reported in?
- *Horses: most important
- Dogs
- Goats
Villonodular synovitis in horses
- Occurs in metacarpo-phalangeal (fetlock) joint
- Associated with lameness and joint effusion
- May produce erosion and proliferation of bone at distal end of the third metacarpal (cannon) bone
What is the most common neoplasm involving joints in dogs?
- Periarticular histiocytic sarcomas
- Malignant
o Often metastasized at time of diagnosis - Other joints can arise in animals but rarely
