Rheumatology Flashcards
What is a joint?
- A joint is the part of the body where two or more bones meet to allow movement.
- The greater the range of movement, the higher the risk of injury because the strength of the joint is reduced.
- The six types of freely movable joint include ball and socket, saddle, hinge, condyloid, pivot and gliding.
What is a ligament?
- A ligament is a fibrous connective tissue which attaches bone to bone, and usually serves to hold structures together and keep them stable.
What is a tendon?
- A tendon is a fibrous connective tissue which attaches muscle to bone.
- Tendons may also attach muscles to structures such as the eyeball.
Describe the basic anatomy of a joint?
Bone –> ligament –> fibrous capsule –> synovial membrane –> synovial joint –> articular cartilage –> articulating bone
What is the purpose of the articular cartilage?
- Reduces friction
- Shock absorption
What is the purpose of the synovial membrane?
- Highly vascularised
- Secretes & absorbs SF
What is the purpose of the synovial fluid?
- Lubrication
- Shock absorption
- Nutrient distribution - hyaline cartilage is avascular and relies on diffusion from SF
What are the main inflammatory markers?
1) ESR (erythrocyte sedimentation rate)
• Rises with inflammation/infection
• Increased fibrinogen makes RBCs “stick together” and therefore fall faster
• Therefore, if ESR rises, the rate of fall is faster
• ESR rises and falls slowly (days to weeks)
• False positives (falsely high)
- Females, age, obesity and SE Asians have higher ESR
• Raised in SLE
2) CRP (C-reactive protein)
- Acute phase protein
- Released in inflammation/infection
- Produced by liver in response to IL-6 (pro-inflammatory cytokine)
• Rises and falls rapidly
o High at 6 hours and peaks at 48 hours
o If patient has infection in 24 hours, ESR won’t have risen yet but CRP will have
3) Auto-antibodies
• Immunoglobulins that bind to self-antigens
What are the inflammatory markers in rheumatoid arthiritis?
- Rheumatoid Factor (RF)
* Anti - Cyclic Citrullinated Peptide (CCP)
What are the inflammatory markers in SLE (systemic lupus erythematosus)?
- Anti-nuclear Antibody (ANA) – binds to antigen within cell nucleus
- Double stranded DNA (dsDNA)
What is osteoarthiritis?
- Non-inflammatory degenerative/(wear and tear) of joints resulting from loss of articular cartilage
- Osteoarthritis is an age-related (degenerative), dynamic reaction pattern of a joint in response to insult or injury
- All tissues of the joint are involved
- Articular cartilage is the most affected – produced by chondrocytes
- Changes in underlying bone at the joint margins
Describe the epidemiology of osteoarthritis?
- Most common type of arthritis
- Especially in elderly and females
- Most common condition affecting synovial joints
- Most important condition relating to disability as a result of locomotor symptoms
- 8.75 million people in the UK seek treatment for OA
What are the risk factors of osteoarthritis?
- Think wear and tear
• Age (uncommon below 50)
o Cumulative effect of traumatic insult
o Decline in neuromuscular function
• Female – prevalence increases after menopause
• Occupation
o Manual labour associated with OA of small joints of hands
o Farming associated with OA of hips
o Football associated with OA of knees
• Genetics
o Most relevant in polyarticular disease
o OA hip less common in Afro-Caribbean and Asian populations
o OA hand rare in black African and Malaysian population.
• Obesity
o Linear relationships between BMI and risk of hip and knee OA
o Not thought to be due to mechanical factors
o Also, association with OA of non-weight bearing joints e.g. hand joints
o Obesity is a low-grade inflammatory state
o Release of: (inflammatory cytokines)
- IL-1
- TNF
- Adipokines (leptin, adiponectin)
- Previous joint trauma
- Rheumatoid Arthritis
- Gout
• Other factors o Local trauma o Inflammatory arthritis – e.g. Rheumatoid Arthritis o Abnormal biomechanics e.g. - Joint hypermobility - Congenital hip dysplasia - Neuropathic conditions
• Osteoporosis reduces risk of OA
Describe the pathology of osteoarthritis?
• Imbalance in process of cartilage breakdown by wear and production by chondrocytes in favour of cartilage breakdown (chondrocyte ECM breakdown)
-Complex process but two main parts:
1) Hyaline cartilage degradation
2) Abnormal chondrocyte homeostasis
- Chondrocytes lose ability to generate and repair cartilage
- Chondrocytes overexpress proteases and cytokines
- Leads to cartilage
breakdown and inflammation - The exposure of the underlying subchondral bone results in sclerosis (narrowing)
- Joint space lost over time
- Some genetic predisposition as well
- Not many leukocytes in synovial fluid
What is the typical presentation of osteoarthritis?
- Elderly with knee/hip pain
- Age related.
- Weight bearing joints
- Improves with rest and worse with activity
- Pain on movement of joint – crepitus.
- Bony swellings – DIP (Heberden’s nodes) and PIP (Bouchard’s nodes)
- XRAY – Osteophytes, joint space narrowing, subchondral cysts and subarticular sclerosis.
