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Abdalla Rayyan

Bahaa Najjar

Mousa Al Abaddy

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As you remember, last time we talked about Osteoporosis and the ways by which we can prevent and treat it. The Doctor said that the video he sent about osteoporosis will help us understand it more.

Now let’s continue talking about some of the most important metabolic

disorders that can affect bones:

RICKETS & OSTEOMALACIA

Both of these diseases are manifestations of vitamin D deficiency or its abnormal

metabolism. Mineralization of bones is one of the various roles that vitamin D

plays in our body, therefore problems with it can result in an accumulation of

unmineralized” Decreased mineralization of bone” matrix leading to the formation of

weak, fragile bones all over the body (it’s a systematic disease). People with

these diseases are at more risk of bends and fractures in their bones and teeth.

Rickets refers to this disorder in children, and since they are still under growth it

is common to see growth problems and deformities as a result of it. On the other

hand, osteomalacia is the adults from and it usually happens during the

remodelling of the bones.

Fortunately, we shouldn’t see these

disorders anymore as they are detected and

treated at an early state.

Note: remember rickets in children, while

Osteomalacia in adults.

Hyperparathyroidism

It is the excess production and activity of parathyroid hormone (as a result of adenoma, carcinoma or hyperplasia) that result in increased osteoclast activity, bone resorption and osteopenia. (We will talk more about it in endocrine system)

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Hyperparathyroidism has three main classifications shown in the table below the Doctor only focused on the following:

Primary Hyperparathyroidism It results from a hyper function of the

parathyroid glands themselves. There is over secretion of PTH due to

adenoma, hyperplasia or rarely, carcinoma of the parathyroid glands. In secondary hyperparathyroidism, the most common cause is chronic

renal failure as it leads to abnormal ion metabolism which in turn results

in continuous stimulation of parathyroid glands.

Usually they are treated by surgery and microscopic tests are done

during and after the surgery to histologically identify the problem in

those glands.

Tertiary hyperparathyroidism is a state of excessive secretion of

parathyroid hormone (PTH) after a long period of secondary

hyperparathyroidism and resulting in hypercalcemia.

Serum calcium is high in both primary and tertiary, while low or normal

in secondary.

Clinically it’s similar to osteoporosis because we do have a loss in the bone mass. If Hyperparathyroidism continues for a long time without treatment, then Osteitis Fibrosa Cystica (OFC) will happen.

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This OFC develops until we have haemorrhage bleeding, haematoma, fibrosis and cystic degeneration. All of these manifestations leading to the creation of a brown mass filled with blood (old and fresh). We call this mass “Brown Tumour” (it isn’t a real tumour).

The presence of somethings in a blood sample helps us determine whether it’s an old or a fresh one. Fresh RBC are usually present in fresh blood samples, while in old ones we usually have hemosiderin laden macrophages. Those macrophages take the iron that comes out of blood cells by phagocytosis.

We also have special stains that can detect the presence of iron in the sample.

OFC is now rarely encountered because hyperparathyroidism is usually diagnosed on routine blood tests and treated at an early age.

PAGET DISEASE OF BONE (OSTEITIS DEFORMANS)

This is a condition of the formation of abnormal bone. We can easily identify

that it’s abnormal when we compare it to a normal lamellar bone.

This skeletal disease can be divided into three sequential phases:

1. Initial Lytic phase where osteoclasts are more active (appears more

black)

2. Mixed osteoclastic-osteoblastic phase

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3. final Sclerotic phase where osteoblasts are dominant (it appears more

white)

All of these phases can be present in the same bone.

Under X-ray, the bone appears abnormal and we can see that some parts are

really shiny and more white while others are darker and more black. But if we

study a sample under the microscope we’ll observe a certain structure called

“mosaic form”.

Paget disease affects 1% of the US population and it varies according to

geography.

Some environmental and genetic factors play a role in this disease so we can

see it in some families more than others.

50% of familial Paget and 10% of sporadic have SQSTM1 gene mutations

(+RANK & - OPG) Some theories have been made that Paget Disease can be

caused by virus infections (measles and RNA viruses), yet nothing have been

proved yet.

Paget disease clinically

85% of the cases are polystotic, while 15% are monostotic. This means that in

most of the cases it happens at multiple bones therefore it is almost

systematic.

Axial and proximal (mainly femur) skeletons are more affected than other

bones.

Most of the cases are mild and asymptomatic therefore they are unnoticed.

But as it develops some pain may be felt as a result of micro fractures or nerve

compressions.

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The more severe forms of Paget Disease have several complications like:

Leontiasis ossea (lion face) –not common-

platybasia (invagination of skull base)

secondary osteoarthritis

fractures

osteosarcoma (seen in 1% of Paget Disease patients) Diagnosis:

By X-ray (as we said earlier)

Increased serum Alkaline Phosphatase

Normal Ca and PO4 (therefore we can rule out osteoporosis and Hyperparathyroidism)

Fractures

Fractures are important because they are the most common pathology of the bones.

It is the loss of bone integrity resulting from mechanical injury and/or diminished bone strength

Fractures usually happen more in long bones than they do in flat bones.

Types of fractures:

Simple: skin is intact

Compound: communicates with overlying skin

Displaced: ends aren’t aligned

Stress: repetitive slow progressive

Greenstick: soft bone fracture (common in children) sometimes it doesn’t appear directly under x-ray

Pathologic: bone is abnormal due to tumours or any other disorder

Spiral: most common case is when kids are held from their hand improperly

Comminuted : multiple pieces

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NOTE : NOT ALL DETAILS ARE INCLUDES IN THIS SUMMARY .