Musculoskeletal System Flashcards by Oliver Taylor

The outer layer of bone is called___________. It makes up __% of the bone mass and is very______and _________

Cortical bone
Makes up 80%
Very dense and compact

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The inner layer of bone is called ___________ or _________ bone. It is less _______ and _________ than the outer layer

Cancellous or trabecular

Stiff and Strong

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Joints are composed of 3 parts…….

Fibrous capsule
Cartilage
Synovial Membrane

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Intramembranous Ossification is a model of __________. It occurs when…….

Bone Formation

It occurs when mesenchymal cells differentiate into osteoblasts which form bone

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Endochondral Ossification is a model of __________. It occurs when

Bone formation

It occurs when a cartilage model, created by chondrocytes, is converted to bone by mineral deposition

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What is bone remodeling?

The process by which old bone is resorped and new bone is layed down

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What are osteoclasts?

Osteoclasts are multi-nucleated cells that resorp bone
They connect to bone via the protein integrin
When attached they become polarised

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What are osetoblasts?

Active bone forming cells that produce a collagenous bone matrix

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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

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What are the risk factors for osteoporosis

Female Gender
Low Ca intake/absorption
Renal Disease
White/Asian
Sedentary Lifestyle
Alcohol and Drug use
Low body weight

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What are the 2 major pathogenic processes for osteoporosis?

Poor bone mass acquisition in adolescence

Accelerated bone loss during the 6th decade

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What causes poor bone mass acquisition?

Hormone deficiencies and malnutrition along with decreased physical activity

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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

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What chemicals increase Bone formation?

Growth Hormone
Vitamin D metabolites
Gonadal steroids

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What chemicals decrease Bone formation?

Glucocorticoids

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What chemicals increase Bone resorption?

Glucocorticoids
Thyroid Hormone
High doses of Vitamin D metabolites

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What chemicals decrease Bone resorption?

Calcitonin

Gonadal Steroids

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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

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What are some initial tests for osteoporosis?

Blood cell count
Ca and PO4 levels
Kidney and Liver Function tests
TSH, Oestrogen and Testerone levels

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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

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What is a urinary marker to show bone resorption has occurred?

Collagen cross-link fragments found in urine

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What is DEXA and what does it stand for?

The most popular BDM test, Dual-Energy X-ray absorptiometry

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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

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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

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What factors influence who should be treated for osteoporosis ?

``` Increasing age Declining BDM Prior fractures 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?

Yes

Should you treat a women with osteoporosis and fractures

Yes

Should you treat a women with osteopenia and a fracture?

Yes

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 Bisphophonate use 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?

No treatment

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.

Fibrous Structure Thickness

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:

Chondrocytes Collagen Proteoglycans Water

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 | Aggrecan

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 Morning stiffness Instability Loss of Function Bony Enlargements at the joint Joint Deformity/Malalignment ```

OA usually affects the ______________?

Weight-bearing joints

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?

``` Old Age Female Gender Family History Smoking Consumption of too much coffee ```

What are the signs/symptoms of RA?

``` Morning Stiffness Arthritis in 3 or more areas Hand Joints involved Symmetric Arthritis Rheumatoid Nodules Positive test for Serum Rheumatoid factor Radiographic Changes ```

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 | Autoimmune

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 Corticosteroids 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

Polymorphonuclear leukocytes | Mono-sodium urate crystals

What are the treatments for acute gouty arthritis?

NSAIDs Corticosteroids Colchicine (Anti-imflammatory but not analgesic)