Musculoskeletal Disorders Flashcards
What are osteoblasts?
Bone forming cells, have role in mineralization, produce type I collagen, key role in osteoclast differentiation
What are osteocytes?
Differentiated osteoblasts (hardened from minerals, surrounded in osteoid), become buried in matrix, coordinate bone remodelling
What are osteoclasts?
Bone resorptive cells, large and multinucleated, contains lysosomes filled with hydrolytic enzymes
What are the stages of bone remodelling?
Activation, resorption, reversal, formation, quiescence
What are the key steps in bone remodelling?
Begins with osteoclasts, resorb mineral component of matrix and secrete protease to digest protein matrix, osteoblasts migrate to resorbed surface and lay down new bone (protein matrix and then becomes mineralized), osteoblasts become buried and becomes osteocytes
What is RANK?
Receptor activated nuclear factor Kappa-B, expressed on surface of osteoclasts and osteoclast precursors
What is RANKL?
Ligand for RANK, plays key role in osteoclast formation/function/survival
What happens when RANKL binds to RANK?
Osteoclast differentiation as well as bone resorption
What serves to prevent resorption caused by the RANK/RANKL pathway?
OPG (osteoprotegeren) which prevents the binding of RANKL to RANK, produced by osteoblasts
What decreases the production of OPG?
Glucocorticoids and proinflammatory cytokines (TNF-a, IL-1)
What are some of the key players in bone health?
Proinflammatory cytokines (IL-1, TNF-a), vit D, nutrients, parathyroid hormone, sex hormones (estrogen), glucocorticoids
What is the action of parathyroid hormone?
Acts on kidney to resorb calcium from renal tubules to increase amount in blood, increase Vit D consumption, increases bone resorption
What is the role of estrogen in bone health?
Inhibits bone resorption, blocks IL-6 and IL-6 is potent stimulator of resorption. Also protects bone from resorption effects of PTH
What are some necessary nutrients for bone health?
Calcium, vit D, protein, Vit K, folate and B12
What is osteoporosis?
Metabolic bone disease, decreased bone mass (bone mineral score of less than -2.5 on DEXA scan), bone formation not equal to bone resorption
What are some signs of osteoporosis?
Usually considered to be silent, first sign is often a fracture
What is sarcopenia?
Gradual and generalized loss of skeletal muscle mass and strength with risk of adverse outcomes. Neurogenic, metabolic, and morphologic changes
What is a challenge with sarcopenia?
Hard to tell whether just normal aging process or abnormal
What is the most movable and complex joint?
Synovial joint
What is the composure of a synovial joint?
Fibrous joint capsule, synovial membrane, joint cavity (space), synovial fluid, articular cartilage (covers the bony surface)
What is arthritis?
Common alteration in the articular system, characterized by inflammation, cartilage destruction, bony spurs and sclerotic lesions
What are three key types of arthritis?
Rheumatoid arthritis (inflammatory), osteoarthritis (hypertrophic), gout (metabolic)
What occurs in osteoarthritis?
Disruption of integrity of collagen network, catabolism of cartilage, primary lesion appears on cartilage
What occurs as a result of catabolism of cartilage?
Breakdown of cartilage into the synovial fluid, initiates an inflammatory response by synoviocytes, results in lesions on the cartilage
What occurs in osteoarthritis as result of activation of inflammation?
Activated synovial macrophages that cause synovitis, cytokines released into synovial fluid, ROS and proteinases
What are some clinical manifestations of osteoarthritis?
Occurs later in life, slow onset, joints ache and are tender with little swelling, often begins on one side of body and usually localized to one set of joints, morning stiffness <1 hour and returns with activity
What is rheumatoid arthritis?
Autoimmune condition, synovial membrane inflammation with systemic signs, ATROPHIC
What occurs in the inflammatory response in rheumatoid arthritis?
Antibodies against self-antigens and inflammatory cytokines in synovial membrane, inflammatory cytokines convert the synovium into thick, abnormal layer (pannus), cells in the synovial membrane hypertrophy and proliferate, RANKL activated
What are rheumatoid factors?
Normal antibodies that turn into autoantibodies and attack the host tissues, bind with self-antigens in the blood and synovial membrane and form immune complexes
What are some clinical manifestations of rheumatoid arthritis?
Begins anytime, more rapid progression, joints painful/stiff/swollen, affects small and large joints on both sides of body (symmetrical), morning stiffness >1 hour, systemic symptoms
What are some risks for gout?
Metabolic syndrome, poor lifestyle, excessive alcohol, hyperlipidemia, urate-elevating medications, history of urolithiasis, CKD/renal disease
What characterizes gout?
Excess burden of uric acid
What occurs from hyperuricemia?
Crystallization of uric acid within joints that results in gout
What is uric acid?
Waste product from breakdown of purines
What are purines?
Normal chemical compound, can have endogenous (metabolism of nucleic acid, DNA/RNA) and exogenous (from meat, beers, etc.)
What are some clinical manifestations of gout?
Night attacks, moderate pain in lower extremity joints (big toe, lower body), gouty tophi (hard, nodular lesions under skin)
Who is commonly affected by gout?
Middle aged men more commonly, postmenopausal women (renal excretion of uric acid decreases d/t loss of estrogen
What are some management options for gout?
Promote better health, limited intake of purine-rich foods, beer, and fructose corn syrup (sucrose contributes to increase in production of uric acid)
What are the two categories of back pain?
Back dominant or leg dominant
What characterizes back dominant pain?
Radiates down back, relief/aggravation with movements, can come and go in spasms, can be perceived as nerve pain but stays within borders of back
What is leg dominant pain?
Compression of a nerve root, strangulation of sciatic nerve as it crosses through sciatic notch, pain extends past knee, commonly L5-S1 distribution, neurogenic claudification
What are some RED flags of back pain?
Compromise to spinal cord/cauda equina (issues with bowels, bladder, etc.), infection/fever, fracture, inflammatory conditions, neoplasms/symptoms
What is cauda equina?
Extreme pressure and swelling of nerves at end of spinal cord, controls function of bladder/bowel, medical emergency
What are some yellow flags with back pain?
Increased risk mechanical back pain will progress to persistent, belief back pain is harmful, movement is harmful, low mood
When is treatment recommended for back pain? (ex: diagnostics)
When red or yellow flags present
What is nociceptive pain?
Response that happens when activation of high-threshold afferent fibers (mechanical, chemical, temperature), relatively predictable
What are three types of pain?
Nociceptive, neuropathic, nocioplastic
What is neuropathic pain?
Distorted/persistent pain that occurs when aspects of nervous system damaged
What is nocioplastic pain?
Pain experience that deviates from typical, there’s an absence of identifiable injury or damage
How does pain signal occur?
Through brain- analyzes information from tissues and receptor systems and determines level of threat/output
What makes up the pain system?
Nerves, cells, neurotransmitters and influenced by immune system/endocrine system/microbiome
What is central sensitization with pain?
Occurs when nervous system is persistently in high activity state, decreases sensitivity to fire action potentials, altered experience of pain
How can fractures be classified?
As complete or incomplete, open or closed
What are some types of incomplete fractures?
Greenstick, buckle, bowing
What is a greenstick fracture?
Cracks on one side (splits spongy bone), not all the way through, relatively unstable
What is a buckle fracture?
Cortex of the bone buckles but does not break, stable fracture
What is a bowing fracture?
Longitudinal force applied to bone, common in children
What are three other classifications of bone?
Pathologic (break at weakened site of pre-existing abnormality), stress (repeated force over time, athletes), and transchondral (fragmentation and separation of portion of articular cartilage that covered end of bone at a joint)
What is dislocation and sublaxation?
Dislocation is temporary displacement of a bone from normal position in a joint, sublaxation is partial loss of contact between two joint surfaces W
What is osteomalacia?
Metabolic disease characterized by inadequate and delayed mineralization of osteoid (unmineralized part of bone matrix) in mature compact and spongy bone
What is a common cause of osteomalacia?
Vit D deficiency, or liver disease
How does vit D deficiency contribute to osteomalacia?
Crystallization of minerals in osteoid needs calcium and phosphate, vit D deficiency disrupts mineralization b/c Vit D normally regulates/enhances absorption of calcium from intestine
What is osteomyelitis?
Bone infection, commonly caused by bacteria but can be caused by fungi/parasites/viruses
What is exogenous osteomyelitis?
Infection that enters from OUTSIDE body (ex: through open fractures, wounds, etc.) and spreads from soft tissues to bone
What are the different types of bone tumors?
Osteogenic (osteosarcoma), chondrogenic (chondrosarcoma), collagenic (fibrosarcoma), myelogenic (myeloma)
What is the bone matrix?
Intercellular substance of the bone that forms most of the mass of bone, contains inorganic and organic material
What are inorganic materials that compose the bone matrix?
Bicarb, citrate, magnesium, sodium, potassium ions and mainly calcium hydroxyapatite
What are organic materials that compose the bone matrix?
Collagen fibers (type I), proteoglycans, glycoproteins
What is hydroxyapatite?
Inorganic mineral component in bone and teeth, plays role in the structural strength of bone and in bone regeneration, made up of calcium and phosphate
Where is spongy bone found in long bones?
The epiphysis (top and bottom portions), found beneath cortical bone
What components of the bone matrix give bone compressive strength?
Hydroxyapatite (minerals provide the compressive strength)
What structure is present in spongy bone and absent in compact bone?
Trabeculae (thin spindles of bone tissue that form irregular meshwork of spongy bone)
What is the appendicular skeleton?
Upper and lower extremities, pelvis
What is the axial skeleton?
Made up in bones in the head, neck, back, and chest
Where does growth in long bones occur?
Epiphyseal plate (between the epiphysis and diaphysis)
Which molecule prevents a muscle contraction from occurring when muscle is at rest?
Troponin-tropomyosin complex prevents actin from binding to myosin
What are types of fibrous joints?
Sutures, syndesmoses, gomphoses
What is the contractile subunit of myofibril in a skeletal muscle cell?
Sarcomere
What is released from the sarcoplasmic reticulum to initiate a muscle contraction?
Calcium (stored in sarcoplasmic reticulum, released to initiate cross-bridge cycle for muscle contraction)
What is a strain?
Damage to the muscle
What is a sprain?
Damage to ligament
