Bones, Fractures & Osteoporosis (uon) Quiz

1. Briefly describe the differences between woven bone and lamellar bone. Give an example of where you'd see woven bone.

Spongy (trabecular) bone = less dense bone tissue with a sponge-like appearance. Found at the ends of long bones and within flat bones.

Compact (cortical) bone = consists of solid, dense bone tissue. Found predominantly in the shafts of long bones.

Osteoclasts = cells responsible for bone resorption and breakdown. They play a role in bone remodeling and repair.

Woven (primary) bone = haphazard organisation of collagen fibres. Weaker. Produced when osteoblasts produce osteoid quickly. It is initially what all foetal bones are made of and is seen in adults after fractures or in diseases such as Paget's.Lamellar (secondary bone) = parallel alignment of collagen fibres means it is stronger. Mature, healthy bone.

The correct answer provides a clear distinction between woven and lamellar bone, mentioning their organization and strength. The incorrect answers provide descriptions of other types of bone tissue and the function of osteoclasts, but they do not address the specific differences between woven and lamellar bone.

Explanation

The correct answer provides a clear distinction between woven and lamellar bone, mentioning their organization and strength. The incorrect answers provide descriptions of other types of bone tissue and the function of osteoclasts, but they do not address the specific differences between woven and lamellar bone.

2. Cortical bone is the hard outer layer which gives bone their smooth, white, solid appearance. True or False? This type of bone makes up 80% of skeletal mass and is important for weight-bearing.

False - cortical bone is only found in the hands and feet

False - cortical bone is soft and pliable

False - cortical bone is not involved in weight-bearing

True - due to its high resistance to bending and torsionExtra info: it consists of multiple microscopic columns each called an osteon. These surround a central canal called a Haversian canal. These go in the direction of force applies to the bone. Between the columns are osteocytes which trapped and maintain bone. The osteon canals are connected by Volkmann's canals at right angles. Remember bone contains blood-vessels, is constantly breaking down and rebuilding.

Cortical bone is indeed the hard outer layer of bone that makes up a significant portion of skeletal mass, providing strength and stability for weight-bearing activities.

Explanation

Cortical bone is indeed the hard outer layer of bone that makes up a significant portion of skeletal mass, providing strength and stability for weight-bearing activities.

3. There are two types of lamellar bone cortical and cancellous (spongy). Which one would you expect at the end of long bones?

Compact spongy bone is found at the ends of long bones near joints and in the vertebrae.

Cortical (compact) bone is found at the ends of long bones near joints and in the vertebrae.

Trabecular bone is found at the ends of long bones near joints and in the vertebrae.

Cancellous (spongy, trabecular) bone is found at the ends of long bones near joints and in the vertebrae. It is less dense and more flexible than cortical (compact bone)

Cancellous bone is the correct type of bone found at the ends of long bones, as it is less dense and more flexible compared to cortical bone.

Explanation

Cancellous bone is the correct type of bone found at the ends of long bones, as it is less dense and more flexible compared to cortical bone.

4. Describe the effects that vitamin D has on:a) calcium and phosphate absorption from the small intestineb) PTH release from the parathyroid gland.

A) Vit D decreases Ca absorption but increases phosphate absorption. b) Vit D has no effect on PTH release from the parathyroid.

A) Vit D has no effect on Ca and phosphate absorption. b) Vit D has no effect on PTH release from the parathyroid.

A) Vit D decreases Ca and phosphate absorption. b) Vit D stimulates PTH release from the parathyroid.

A) Vit D increases Ca and phosphate absorption. These are needed for healthy bone density. b) Vit D inhibits PTH release from the parathyroid. Note: the role of vitamin D in building up bones is quite complicated. Vit D stimulates osteoclast activity but is also important for bone formation as we need it for enough Ca. Take-home: adequate vitamin D is needed for healthy bones.

Vitamin D plays a crucial role in calcium and phosphate absorption for maintaining healthy bone density. It also helps in inhibiting PTH release from the parathyroid gland. Therefore, options that state the opposite effects or no effect are incorrect.

Explanation

Vitamin D plays a crucial role in calcium and phosphate absorption for maintaining healthy bone density. It also helps in inhibiting PTH release from the parathyroid gland. Therefore, options that state the opposite effects or no effect are incorrect.

5. Vitamin D is first activated by what and where does the first and second hydroxylation take place?

Vit D is activated by UV lightIt is hydroxylated in the liver and then the kidney

Vitamin D is first activated by sunlight. It is hydroxylated in the pancreas and then the skin.

Vitamin D is first activated by ingestion. It is hydroxylated in the lungs and then the spleen.

Vitamin D is first activated by exercise. It is hydroxylated in the stomach and then the intestines.

Vitamin D is activated by UV light, not sunlight, ingestion, or exercise. It is hydroxylated in the liver and then the kidney, not in the pancreas, lungs, stomach, or intestines.

Explanation

Vitamin D is activated by UV light, not sunlight, ingestion, or exercise. It is hydroxylated in the liver and then the kidney, not in the pancreas, lungs, stomach, or intestines.

6. PTH is secreted by chief cells in response to low levels of what?

Low levels of Ca stimulate PTH release. This is because PTH works to increase resorption of Ca and phosphate - i.e. it will raise serum Ca. It also increases the effects of vit D. Note: remember that high Ca and high Vit D will inhibit PTH release. This helps it keep it in balance.

High levels of Phosphate

Low levels of Vitamin D

High levels of Ca

When considering the role of PTH in regulating calcium levels, it is important to understand the relationship between PTH, Calcium, Vitamin D, and Phosphate. PTH acts to increase serum calcium levels, thus it is released in response to low levels of calcium. High levels of calcium or vitamin D will inhibit PTH release. Phosphate levels do not directly stimulate PTH secretion.

Explanation

When considering the role of PTH in regulating calcium levels, it is important to understand the relationship between PTH, Calcium, Vitamin D, and Phosphate. PTH acts to increase serum calcium levels, thus it is released in response to low levels of calcium. High levels of calcium or vitamin D will inhibit PTH release. Phosphate levels do not directly stimulate PTH secretion.

7. Briefly describe in what situations a fracture could heal by primary (direct) fracture healing.

Primary healing can occur when there is significant movement between the two fracture fragments.

Primary healing can happen when there is an insufficient blood supply to the fracture site.

Primary healing is possible when there is a visible callus formation on X-ray imaging.

Primary healing can occur when there is absolute stability to a fracture. This means that the two fragments are compressed together anatomically excellently, with minimal or no movement, and a good (uncompromised) vascular supply. There will be no callus visible on XR. Extra Info: primary healing occurs when the two fragments of the fracture are compressed in the perfect anatomical position. This can sometimes be achieved using a 'lag screw' - a type of surgical intervention. This occurs by through fragile pathways between the two fragments called 'cutting cones'. osteoclasts travel through first turning over bone, followed by osteoblasts that lay down new bone.

Primary healing requires absolute stability, anatomical alignment, minimal movement, and good blood supply with no visible callus formation on X-ray.

Explanation

Primary healing requires absolute stability, anatomical alignment, minimal movement, and good blood supply with no visible callus formation on X-ray.

8. What are the 4 stages of secondary healing of fractures, and roughly when does each occur after the fracture?

Soft tissue repair, Ligament development, Nerve connection, Cartilage formation

Swelling reduction, Scar formation, Skin healing, Muscle building

Blood vessel formation, Tissue regeneration, Bone strengthening, Muscle growth

Haematoma Formation (1-7 days): blood vessels rupture, causes inflammatory response, creates fibrin clots and forms a haematoma. Soft Callus (1-3 weeks): a primary callus of granulation tissue (formed of fibroblasts + new blood vessels) replaces the haematoma. Hard Callus (1-4 months): calcification the soft callus occurs. New blood vessels form. By the end of this stage the fracture is 'reunited' by woven bone + people can weight bear. Bone Remodelling (1-2 years): woven bone is replaced by lamellar bone. Woven bone is broken down by osteoclasts and strong, organised lamellar bone is laid down by osteoblasts.

In secondary healing of fractures, the stages include haematoma formation, soft callus formation, hard callus formation, and bone remodelling. These stages occur in a specific sequence and each stage plays a crucial role in the overall healing process.

Explanation

In secondary healing of fractures, the stages include haematoma formation, soft callus formation, hard callus formation, and bone remodelling. These stages occur in a specific sequence and each stage plays a crucial role in the overall healing process.

9. Wrist Fractures - the blue arrow indicates the fracture. What angle should the radial inclination angle normally be?

D) the angle should be 30O - it is deviated in this fracture.

B) the angle should be 45O - it is increased in this fracture.

A) the angle should be 25O - it is flattened in this fracture. You can also see that at the radioulnar joint, the ulnar is higher than the radius due to radial impaction. b) in the lateral view there is dorsal angulation/displacement of the radius c) this is a Colles fracture - classically sustained with a FOOSH (fall on outstretched hand) with an extended wrist. Pic: in 60% of cases the ulnar styloid process is also fractured. It has a classic 'dinner fork' or 'bayonet' shape to the hand and wrist.

C) the angle should be 10O - it is decreased in this fracture.

In a Colles fracture, the radial inclination angle is flattened, deviating from the normal angle of 25O.

Explanation

In a Colles fracture, the radial inclination angle is flattened, deviating from the normal angle of 25O.