Flashcards in Musculoskeletal System Deck (68):
The outer layer of bone is called___________. It makes up __% of the bone mass and is very______and _________
Makes up 80%
Very dense and compact
The inner layer of bone is called ___________ or _________ bone. It is less _______ and _________ than the outer layer
Cancellous or trabecular
Stiff and Strong
Joints are composed of 3 parts.......
Intramembranous Ossification is a model of __________. It occurs when.......
It occurs when mesenchymal cells differentiate into osteoblasts which form bone
Endochondral Ossification is a model of __________. It occurs when
It occurs when a cartilage model, created by chondrocytes, is converted to bone by mineral deposition
What is bone remodeling?
The process by which old bone is resorped and new bone is layed down
What are osteoclasts?
Osteoclasts are multi-nucleated cells that resorp bone
They connect to bone via the protein integrin
When attached they become polarised
What are osetoblasts?
Active bone forming cells that produce a collagenous bone matrix
What is osetoporosis?
A systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue. This causes an increased susceptibility to fracture
What are the risk factors for osteoporosis
Low Ca intake/absorption
Alcohol and Drug use
Low body weight
What are the 2 major pathogenic processes for osteoporosis?
Poor bone mass acquisition in adolescence
Accelerated bone loss during the 6th decade
What causes poor bone mass acquisition?
Hormone deficiencies and malnutrition along with decreased physical activity
What causes accelerated bone loss?
Increased activity of osteoclasts without the same increase in osteoblast activity. Bone is being broken down faster than it is being formed
What chemicals increase Bone formation?
Vitamin D metabolites
What chemicals decrease Bone formation?
What chemicals increase Bone resorption?
High doses of Vitamin D metabolites
What chemicals decrease Bone resorption?
What is BDM?
Bone Density Measurement, the lab test for determining if a patient has osteoporosis. Low BDM and many remodeling markers indicate higher incidence of fractures
What are some initial tests for osteoporosis?
Blood cell count
Ca and PO4 levels
Kidney and Liver Function tests
TSH, Oestrogen and Testerone levels
What are some additional tests undertaken to screen for osteoporosis?
Screening for Hyperparathyroidism
24 hour urine test to rule our hypo/hypercalciuria
Serum Protein electrophoresis to rule out multiple myeloma
What is a urinary marker to show bone resorption has occurred?
Collagen cross-link fragments found in urine
What is DEXA and what does it stand for?
The most popular BDM test, Dual-Energy X-ray absorptiometry
Even though CT scans are more sensitive they aren't used as much to screen for osteoporosis because........
They expose the patient to more radiation
What is a T-score?
The result given by DEXA, it is the number of standard deviations above or below the the mean BDM for a given race/gender
What factors influence who should be treated for osteoporosis ?
Family history of osteoporosis
Risk factors for boneless (hyperparathyroidism, immobilisation etc)
Lots of bone remodeling markers
Should you treat a women with osteoporosis and no fractures?
Should you treat a women with osteoporosis and fractures
Should you treat a women with osteopenia and a fracture?
Should you treat a women with osteopenia and no fractures?
No, however, follow up check should be done in 1-3 years
What are some overall stratagies for treating osteoporosis?
Increase calcium intake (diet or supplements)
Oestrogen Replacement Therapy
Selective Oestrogen Receptor modulators
Weight bearing excercise
Reduce consumption of drugs and alcohol
What do Selective Oestrogen Receptor modulators do?
They inhibit trabecular and vertebral bone loss by blocking the activity of cytokines that cause bone resorption
What do bisphosphonates do?
They bind to mineralised bone structures to inhibit osteoclast activity
If T-score is greater than -1 do you treat the patient?
If T-score is between -2.5 and -1 do you treat the patient?
Treat if fracture present
If T-score is less than -2.5 do you treat the patient?
Treat regardless of fracture or not
The joint capsule is a _______ structure that defines the outer boundary of joints. The ______ of the capsule varies widely depending on the type of joint and the location within a given joint.
What is the synovial lining? What is it's function?
A thin lining of cells (including macrophages and fibroblasts), one to three cells thick, runs beneath the capsule
Cells produce synovial fluid that enters the joint space and
acts as a lubricant.
It stabilises the joint by acting as an adhesive
Cartilage is composed of:
In normal cartilage there is a balance of repair and degradation of the _____________?
Cartilage matrix components
Cartilage has load bearing properties due to the __________ and the osmotic swelling pressure of ___________
Collagen fiber network
What are the three types of Arthritis?
Osteoarthritis, Rheumatoid Arthritis and Gout
What is Osteoarthritis?
Arthritis caused by the breakdown of articular cartilage and characterised by the formation of osteophytes
What are the signs/symptoms of OA
Pain with overuse
Loss of Function
Bony Enlargements at the joint
OA usually affects the ______________?
Describe the 3 step pathogenesis of OA
1. Excessive proteolytic breakdown of cartilage matrix
2. Breakdown products enter the synovial fluid via erosion
3. Synovial cells take up these products causing a chronic inflammatory response
What forms at the margins of the joint?
Osteophytes, or bony spurs, these cause the ragged and irregular surface
What are the treatment options for OA?
Pain relief is the major treatment, via topical, local injections or oral pain relivers
Surgery is considered if pain is hard to manage and function is heavily impaired
What is Arthroscopic Debridement?
The removal of foreign material and damaged cartilage from the joint until healthy tissue is exposed
What is an Osteotomy?
Addition of a wedge of bone to the tibiae to realign the knee. It is designed to take the pressure off the area with arthritis. Usually for patients too young for full replacement
What is a Total Joint Arthoplasty?
Total joint replacement, prosthetic replaces the joint
What is ACI?
Autologous Chondrocyte Injection: Healthy Chondrocytes are removed from the patient, cultured and replaced thereby repairing the cartilage
What is Rheumatoid Arthritis?
A chronic inflammatory disease characterized by uncontrollable proliferation of synovial tissue
What are the risk factors for RA?
Consumption of too much coffee
What are the signs/symptoms of RA?
Arthritis in 3 or more areas
Hand Joints involved
Positive test for Serum Rheumatoid factor
What causes RA?
Unknown, may be an interaction between genes and the environment
Joint damage in RA starts with proliferation of ____________ and ___________ after a triggering incident, possibly __________ or infectious
Synovial Macrophages and Fibroblasts
Blood vessels in joint affected by RA become __________ with small clots or _____________
Occluded with small clots or inflammatory cells
Early diagnosis is critical in treating RA as joint destruction occurs within ____________ after onset of symptoms
a few weeks
What are some drugs that are used to treat RA?
NSAIDs (Non-Steroidal Anti-Inflammatory Drugs
DMARDs (Disease-Modifying Antirheumatic Drugs)
TNF inhibitors (Tumour Necrosis Factors)
What is a Synovectomy?
A type of surgery used to treat RA by removing diseased tissue
What is Gout?
A disease resulting from the deposition of urate crystals caused over production or under excretion of uric acid
The diagnosis of gout depends on the identification of ______________ in the joints, tissue or body fluid
Uric acid crystals
What are the characteristics of acute gout?
Attacks are usually mono-arthritic (affect 1 joint)
Usually affect lower extremities
Mainly Podagra (Gout in big toe)
What is Uric acid?
The end product of purine metabolism, it has no physiological role.
What is Hyperuricemia?
Uric acid levels of 420 umol L or higher, it is a risk factor for developing gout
Gout may be associated with __________ and ___________, therefore examination of the cardiovascular and renal system are essential.
Hypertension and Renal failure
The diagnosis of gout is confirmed by the presence of ______________ and intracellular _______________ in the synovial fluid taken from the affected joint
Mono-sodium urate crystals