Things to know before exam Flashcards
What are some of the main microscopical changes in cartilage structure seen in OA?
- Chondrocyte necrosis (especially in superficial layers)
- Focal clumps of isogenic chondrocytes (due to increased local proliferation)
- Change to fibrocartilage from hyaline (type I collagen rather than type II) – reduces the thickness of articular cartilage; duplicated tidemark and thickening of calcified cartilage merging with subchondral bone
What gene loss is associated with OA and what is it responsible for?
HMGB2 (high mobility group protein 2) – epigenetic protection; uniquely expressed in superficial zone chondrocytes; supports their survival and regulates specific differentiation status; regulates protection of chondrocytes’ DNA; loss leads to superficial zone cell death, loss of progenitor cells and reduced synthesis of ECM contents
How does the inflammatory cytokines are released? What do they cause?
Damaged chondrocytes release stress cytokines (Il1, IL6 and TNF) into joint which cause reaction with synovial membrane resulting in a mild inflammatory process. Inflammatory cytokines influence disease progression, cause further damage to surrounding cartilage and bone, are main cause of pain, stimulate RANKL on osteoblasts and hence increase bone formation
What are the main characteristics of early OA and late OA?
Early OA: loss of superficial zone and changes to ECM; cell clusters
Late OA: continued loss of ECM and chondrocyte hypertrophy
What are some red flags for recognition of severe disease?
Fever or unexplained weight loss
- History of carcinoma
- Immune-suppression
- Ill health and presence of other medical illness
- Severe night pain/progressive pain
- Persistent mono-arthritis
What is enthesitis? What is its clinical feature
Inflammation of tendon to bone attachment; pain on resistant movement
What is De Quervain’s tenosynovitis? What are the clinical signs?
Inflammation of the first extensor tendon sheath containing APL and EPB; pain on resistant movement (on extension of the thumb against resistance), crepitus and positive Finkelstein’s test
What are the main causes of carpal tunnel syndrome?
60% idiopathic, pregnancy, hypothyroidism, RA
What might be the cause of articular and periarticular pain of the elbow?
Articular – trauma, OA
Periarticular – epicondylitis, bursitis
What is frozen shoulder? How can it be treated?
Adhesive capsulitis; shoulder capsule (CT) becomes inflamed and stiff greatly restricting motion and causing chronic pain; reassurance/education, analgesia, injection, physio
What movements are restricted in frozen shoulder?
External rotation the most but also internal rotation and abduction
What is the main sign of rotator cuff tendinitis? What is the treatment?
Painful arc on active and resisted abduction; physio, steroid injection and surgery
What is meralgia peresthetica?
Tingling, numbness and burning pain in the outer part of thigh due to compression of lateral cutaneous nerve.
What is Morton’s neuroma?
Benign neuroma most commonly between 2nd and 3rd metatarsal spaces
What is March fracture?
Fracture of the distal third of one of the metatarsals (2nd or 3rd) occurring because of recurrent stress.
What MHC molecule is strongly associated with Ankylosing spondylitis?
HLA B27
What MHC molecule is strongly associated with RA?
HLA-DR4
What is synovial fluid?
the ultra filtrate of blood with added hydraluronic acid
What two types of proteins are found in synovial fluid?
Albumin (60%) and globulin (40%)
What is the mucin clot test? What is the normal string length?
2-5% acetic acid added to synovial fluid – normal synovial fluid will form a clot surrounded by clear fluid; normal string is 4-6cm
What type of cells are found in subintima and in synovial fluid in RA?
Subintima – lymphocytes
Synovial fluid – neutrophils
What is the function of each of these cells in RA:
a) Th17
b) Macrophages
c) B cells
d) Synovial fibroblasts
a) Orchestrate synovitis and damage, release inflammatory cytokines (IL-17)
b) Secretion of pro-inflam cytokines
c) Auto-Abs secretion (rheumatoid factor and anti-CC/ACPA); present antigen to T cels, stimulate synovial fibroblasts thru cytokines
d) Secretion of MMPs and cathepsins; expression of RANKL and stimulating differentiation of type A macrophages into osteoclasts
What is citrullination and when does it occur?
Changing of arginine to citrylline by deamination by peptifyl arginine deiminase which occur during apoptosis. When apoptosis is too high or clearance is defective, these proteins become extracellular. In some people anti-citrullinated antibodies are formed
What can the ACPAs induce?
They can stimulate osteoiclast differentiation and maturation by inducing RANKL expression and synergy with RANK on osteoclasts to enhance bone erosion
What is Dkk-1? How is it induced and what is its fun?
Dickkopf-related protein 1 expression stimulated by proinflam cytokines on synovial fibroblasts which directly inhibit osteoblast differentiation; it also acts indirectly by inducing expression of sclerostin in osteocytes
What is the downside of microfracture?
Creates fibrocartilage which is less durable and resilient
What is the material used in bone cement? What is the function of cement in THR?
Polymethyl methacrylate (PMMA) used to act as a filler between the bine and the implant
What are the 4 criteria sections for diagnosis of RA? What score must be achieved for the diagnosis of RA?
Joint involvement, serology, acute phase reactants, duration of symptoms; 6 or more/10 = diagnosis of RA
What is hydroxychloroquine? What is its mode of administration? What is its MOA?
Anti-malarial drug given orally with or after food; that blocks Toll-like receptor 9 which recognizes DNA containing immune complexes and hence leads to decreased DC activation and accumulates inb lysosomes increasing the pH and hence decreasing protein modifications
What is hydroxychloroquine? What is its mode of administration? What is its MOA?
What is a DMARD similar to methotrexate? What is its MOA?
Leflunomide; inhibits pyrimidine biosynthesis through inhibition of dihydroorotate dehydrogenase
What biologics inhibit IL-1?
Anakinra (SQ once a day)
Canakinumab
Rilonacept
What biologic is used to inhibit T cells? How?
Abatacept – prevents secondary stimulatory signal from being delivered to T cell; IV infusion once a month
Belatacept – anti-CD28, modulates T cell signaling
What are ADAs? What are their 2 types?
Anti-drug antibodies; neutralizing ADA directly interferes with biological drugs ability to work; non-neutralising ADA may form immune complexes around injection site, reducing drug concentration and pharmacokinetics (eg increased clearance)
Which joint is usually affected by OA?
Base of the thumb
What might be the cause of OA of premature onset?
Previous menisectomy and haemochromatosis
What might be the causes of secondary osteoporosis?
Thyrotoxicosis, Cushing’s syndrome, malabsorption, malignancy, hypogonadism and drugs
Which bisphosphonate is to be taken every day and which once a year?
Every day: etidronate
Once a year: zoledronate
What is the erosive OA?
Severe subset of nodal OA; it is a more inflammatory form of OA primarily characterized by erosions of cartilage in the DIP and PIP joints
What is swan neck deformity?
Hyperextension of PIP and flexion of the DIP
What might be the complications of systemic inflammation in RA?
Anaemia, thrombocytosis, fatigues, osteoporosis, acute-phase response
How does the NOF fracture present?
External rotation of the foot and shortening of the leg
What are the bony insertion points for:
a. Sartorius
b. Hamstrings
c. Rectus femoris
d. Calcaneous
e. Medial epicondyle
a. ASIS
b. Ischial tuberosity
c. AIIS
d. Achilles tendon – gastrocnemius an d soleus
e. Forearm flexors and ulnar nerve
What is fracture dislocation/sublaxation? What can be the complication of it and what is done to prevent it?
Fragment involving joint; the surfaces may result in malalignment, so internal fixation is required
What is pathologic characteristic of the stress fracture? How can it be observed?
Periosteal reaction where osteoblasts proliferating more; well visualized ion bone scintography
What is the length of the healing process for lower and upper limb?
Lower 8wks
Upper 6 wks
What are the main characteristics of the fracture haematoma?
Hypoxic and acidic due to disruption of vessels
describe what happens in the fibrocartilage callus bone remodelling stage
New capillaries organize fracture haematoma into granulation tissue (procallus) fibroblasts and osteogenic cells invade procallus they make collagen fibres which connect ends together chondroblasts begin to produce fibrocartilage
What is the name of a new lateral curve of the spine? What does it usually involve? Who is mostly affected by this?
Scoliosis, usually involved rotation of the vertebrae; girls around puberty mostly affected