Prof. Dr. M. M. PrabhakarMedical Superintendent,Director Government Spine Institute,Prof. & Head Department of Orthopaedics,B. J. Medical College,Ahmedabad.

OSTEOPOROSIS

Osteoporosis, which literally means “porous bone”, is a disease in which the density and quality of bone are reduced.

Bones become more porous and fragile

The risk of fractures is greatly increased

The loss of bone occurs “silently” and progressively

Often there are no symptoms until the first fracture occurs.

Compact bone consists of closely packed cylindrical units called osteons.

The osteon consists of a central canal called the Haversian canal, which is surrounded by concentric rings (lamellae) of matrix.

Between the rings of matrix, the bone cells (osteocytes) are located in spaces called lacunae.

• Spongy bone consists of lattice of fine bone plates (trabeculae) that has small, irregular cavities containing red bone marrow.

• The canaliculi connect to the adjacent cavities, instead of a central Haversian canal, to receive their blood supply.

The bone tissue is composed of a hard matrix of minerals (mostly calcium and phosphorus) that is deposited around protein fibers (collagen).

› Osteogenic cells – are precursor cells for all forms of connective tissue.

› Osteoblasts – are responsible for bone formation that secret the organic substances and mineral salts used in ossification process.

› Osteocytes – are osteoblasts that have stopped laying down new bone, but play a role in the maintaining the cellular activities of the bone tissue.

› Osteoclasts – are cells found on the surface of the bone that are responsible for bone resorption.

Bone resorping cells Use acids or enzymes to

dissolve calcium and collagen of old bone

Dissolved calcium reenters blood stream and is carried to various parts of the body

Osteoblasts are cells that build bones.

Produce collagen Then coat the collagen with

a protein "glue" that holds the calcium in place.

Calcium from the bloodstream then automatically adheres to the collagen, forming new bone material.

Bone cells These maintain bones by

maintaining the concentration of calcium

The terms osteogenesis and ossification are often used synonymously to indicate the process of bone formation.

Osteoblasts, osteocytes and osteoclasts are the three cell types involved in the development, growth and remodeling of bones.

Bone formation occurs by three co-ordinated processes: initially osteoblasts deposit collagen rapidly, without mineralization,

producing a thickening osteoid layer.

The ossification process can occur by two ways:

› Intramembranous ossification - involves the replacement of sheet-like connective tissue membranes with bony tissue.

› Endochondral ossification involves the replacement of hyaline cartilage models with bony tissue.

During childhood and the early years of adulthood, while the epiphyses are still open, the skeleton grows in length (growth), and the bones expand in diameter and achieve their external shape (modeling).

During bone modeling, osteoblasts and osteoclasts work independently of each other and on different bone surfaces - often over large surface areas.

The net balance is positive (i.e. there is increased bone mass) and bones reach their final external form and high bone density during this period.

Both the growth and the modeling processes are controlled by hormones and by mechanical forces - mechanical usage.

Around the age 20-25 years, peak bone mass is achieved as a result of these processes. Subsequently, there is continuous revision of bone through resorption and formation, a process known as remodeling.

Remodeling allows for the degradation of worn out bone from damaged and/or unused regions and for the deposition of minerals in regions of greater stress.

Activation : Activation: via recruitment of osteoclasts by cytokines like IL-1, IL-6

Resorption: via proteo-lytic enzymes & acids secreted by osteoclasts

Coupling: recruitment of osteoblasts & secretion of matrix

Mineralization: deposition of Ca & phosphorous

OsteoclastOsteoclast

ResorptionResorption

OsteoblastOsteoblast

Osteoblast Osteoblast RecruitmentRecruitment

Osteoid Osteoid DepositionDeposition

MineralizationMineralization

The Bone Remodeling CycleThe Bone Remodeling Cycle

► High Remodeling

Hypogonadal (including post-menopausal)

Hyperparathyroidism Hyperthyroidism Others

► Low Remodeling

Involutional (Aging) Glucocorticoids (high dose) HIV

Normal RemodelingNormal Remodeling

OsteoOsteocclast Overactivitylast OveractivityHypogonadal StatesHypogonadal States

Parathyroid and ThyroidParathyroid and Thyroid

OsteoOsteobblast Dysfunctionlast DysfunctionInvolutional (Aging)Involutional (Aging)

GlucocorticoidsGlucocorticoidsHIVHIV

To supply Calcium throughout our body

To replace old bones Regeneration ensures

bone remains strong and flexible

Calcium Regulating Hormones

Glucocorticoids

Growth Factors

Tumor Necrosis Factors

1, 25 (OH)2 Vit D (Calcitriol)

Calcitonin

Parathyroid Hormone (PTH)

Calcitriol Calcitonin PTH

Absorbs Ca from intestine

Calcitonin α serum Ca

PTH α 1 / Serum Ca

Bone resorption

Ca absorption from intestine

Ca reabsorption from urine

Bone formation

Ca absorption from intestine

Ca reabsorption from urine

Aging From 40s onwards bone

mass starts declining gradually

Bone formation <Bone resorption

Bones become weak and danger for osteoporosis sets in

Normal Osteopenia Osteoporosis Severe

Osteoporosis

NIH/ORBD (www.osteo.org), 2000

Osteoporosis is responsible for >1.5 million vertebral and non-vertebral fractures annually

Spine, hip, and wrist fractures are most common

OtherVertebralHipWrist

15 % 19 %

19 %

46 %

• Osteoporosis : Almost 50 % of post menopausal women over 50 years. Affects 200 million women worldwide

Osteoporotic fractures

• Approximately 30% of women over the age of 50 have one or more vertebral fractures

• Approximately one in five men over the age of 50 will have an osteoporosis-related fracture in their remaining lifetime

Osteoporosis is highly prevalent in India.

An estimated 61 million people in India are reported to be affected.

Life span of an average Indian has also increased and this also contributes to the increased incidence of osteoporosis.

Recent data indicate that Indians have lower bone density than their North American and European counterparts

Reported that osteoporotic fractures occur 10-20 years earlier in Indians as compared to Caucasians

Projected number of osteoporotic hip fractures worldwide

Projected to reach 3250 million in Asia by 2050

Adapted from Cooper C et al, Osteoporosis Int, 1992;2:285-289

Estimated no of hip fractures: (1000s)

1950 2050

600

3250

1950 2050

668

400

1950 2050

742

378

1950 2050

100

629

Total number ofhip fractures:

1950 = 1.66 million 2050 = 6.26 million

Spine fractures (vertebral compression fractures) can cause intense back pain, and may eventually result in a gradual loss of movement and the inability to carry out daily chores.

Arrr……hh..Ouch

They can lead to loss of height, and in severe cases the spine may curve to form what is termed a “hump”.

Most common fractures (46%)

Insidious

Progressive

Often unrecognized

Associated with

› Deformity, height loss, back pain

› Morbidity and mortality

Predict future vertebral and non-vertebral fractures

Entire skeleton can be involved› Wrist› Ankle› Pelvis› Humerus› Rib› Others

Associated with significant disability

Most serious clinical event Morbidity is high

› 50% do not regain independence› 50% do not regain previous mobility

Mortality is high› 1 in 5 patients die within 1 year

Patients not treated for osteoporosis

Hip FractureHip Fracture

Hip fractures almost always require surgery and in about a third of patients, result in loss of independent living.

Low BMD Fracture after 50 years Age 65 years Maternal history of fracture after 50 years Low body weight (125 lb) Smoking Corticosteroid use Other secondary causes

All postmenopausal women with the following:

Risk of FractureRisk of Fracture

40%

Unable to walk independently

30%

Permanentdisability

20%

Death within one year

80%

One year after an

hip fracture:

Pat

ien

ts (

%)

Unable to carry out at least one independent activity of daily living

1996 new cases,all ages184 300

750 000 vertebral

250 000 other sites

250 000forearm

250 000hip

0

500

1000

1500

2000

Osteoporotic Fractures

HeartAttack

Stroke BreastCancer

An

nu

al in

cid

enc

e x

10

00

1 500 000

annual incidenceall ages

513 000

annual estimatewomen 29+

228 000

annual estimatewomen 30+

The incidence of osteoporotic fractures is highest in women and

more than heart attack, stroke and breast cancer put together

Non-modifiable Caucasian /Asian race Advanced age Female sex Premature menopause (<45 years)

Modifiable Cigarette smoking Excessive alcohol intake Inactivity Low body weight Poor general health Prolonged immobilization

If you are beyond 50 years of age And feel you have more than onerisk factors

Or

had a broken a bone after a minor bump or fall

Need to consult immediately

Initial physical examination

X-ray. Laboratory

blood tests. Bone

densitometry (Bone Mineral Density-BMD).

As osteoporosis has no obvious symptoms other than a fracture when the bone is already significantly weakened, it is important to go to the doctor if any of the risk factors apply to you.

A number of different types of BMD tests are available, but the most accurate is DXA (dual energy X-ray absorptiometry).

DXA is a low radiation X-ray capable of detecting quite low percentages of bone loss. It is used to measure spine and hip bone density.

The World Health Organization has defined a number of threshold values for osteoporosis.

The reference measurement is defined as healthy bone density in a young female of around 25 years.

‘ T- score’ is number that indicates whether or not bone loss has occurred

-1

- 2.5

Normal bone mass

Osteopenia

Low bone mass

Osteoporosis

T score > -2.5

If the results of your BMD test show osteopenia or osteoporosis it does not automatically mean that you will have a fracture.

There are a number of therapies available that your doctor might prescribe that slow down the rate at which bone loss occurs and help prevent fractures.

In addition, there are important nutritional and lifestyle changes that you can make to help reduce your risk

of fracture.

Encourage good general nutrition

Promote a diet with adequate calcium content

Promote adequate vitamin D intake

Regular weight-bearing exercise

Avoid smoking and alcohol

Prevention of falls

1. Exercise is not just important to generalhealth, it helps build bone mass in youth and slows down bone loss in adults

Weight-bearing exercise in particularis good for bone health. This type ofexercise includes walking, jogging,tennis and similar sports, aerobics anddancing.

Both calcium and vitamin D are essential to maintain healthy bones. As we grow older we absorb calcium from food less efficiently. This means that over time we need higher amounts of calcium

Milk and other dairy products like cheese and yogurt are the most readily available dietary sources of calcium.

Other good food sources include Tofu, soya bean, Apricots, Almonds, fishes and fruits like Orange

Good dietary sources of vitamin D include oily fishes,fortified dairy foods and egg yolks

Avoid : caffeine , high salt diet, alcohol – which increase calcium loss

Take an additional measure to reduce the risk of fractures by fall-proofing your home.

Reduce clutter at floor level Wear well-fitting shoes or slippers Make sure surfaces are slip-proof: rugs should have a skid-proof

backing Have grab rails installed in the bathroom and toilet Make sure that lighting is bright enough. Have regular eye checkups –vision is crucial in judging distances

and detail.

Calcium and Vitamin D supplementation is basic requirement before any other treatment is begun.

Recommended daily dietary allowance (RDA) › Vitamin D (RDA : 400 – 800 IU)› Calcium (RDA : 1200 – 1500 mg/day)

Treatment Options

Prevent Resorption

Hormone Replacement Therapy (HRT)

Raloxifene

Bisphosphonates

Build New Bone

Parathyroid hormone (PTH) - Teriparatide

• There is no cure, but several medications have been approved

• Each stops or slows bone loss, increases bone density, and reduces fracture risk.

Oral : Alendronate – daily or weekly dose Risedronate – daily or weekly dose Ibandronate – monthly dose IV

› Intravenous Ibandronate – inj. once in 3 month › IV Zolendronate – inj. once a year

All biphsphonates have been shown to act quickly (within one year), to maintain bone density and to reduce the risk of having fractures

They differ in their degree of reduction of risk

Health professionals Osteoporosis patient support groups Practical tips Get the information regarding treatments available

lessening the feelings of isolation and depression experienced

by many patients with severe osteoporosis