Skeleton Disorders

Question 1

1. Know the definitions of complete fracture and the types of complete fractures: comminuted spiral transverse, oblique and linear.
2. Know the definitions of incomplete fracture and the types of incomplete fractures: greenstick, torus and bowing.

Answer 1

Complete – the bone is broken entirely
Comminuted – two or more fragments present
According to direction of break – spiral (encircles the bone), transverse (straight across), oblique (at an angle), linear (along the length of the bone).
Incomplete – bone is damaged but still in one piece (tend to occur in children)
Greenstick – only one side is broken
Torus – the outer portion of the bone buckles, but doesn’t break
Bowing – in bone pairs (tibia/fibula, radius/ulna) – one bone breaks, but the other only bends. Difficult to treat, as have two different situations

Question 2

3. Define open vs closed fractures

Answer 2

Open (compound) – skin is broken

Closed (simple) – skin is intact

Question 3

4. Define the 3 classifications of fractures, based on cause.

Answer 3

Transchondral – occurs at end of bone: fragmentation of articular cartilage (tends to occur in adolescents).
Pathologic – due to a prior disease that weakens a bone (e.g., tumors, infections)
Stress
in normal bone (due to repeated stress, e.g., in a new sport, muscle gains strength before bone, and can get microfractures with repeated stress).
in abnormal bone (bone has lost ability to deform and recover and injury occurs with normal use, e.g., rheumatoid arthritis, osteoporosis) Can overlap with pathologic.

Question 4

5. Describe direct healing of a fracture and when this can occur.

Answer 4

Occurs when adjacent bone surfaces are in contact with each other (e.g., ends of bone held in place by plates/pins)
Osteoclasts move across space from each side, dissolving into bone on other side of break, followed by osteoblasts that fill in bone behind the osteoclasts (“cutting cones”)
No callus formation

Question 5

6. What is one similarity between bone tissue and hepatic tissue?

Answer 5

Similar to endochondral bone formation
Involves formation of callus, with subsequent bone remodeling
Most often observed with use of cast or other non-surgical treatment
Bone tissue is unique (except for liver), in that new bone tissue is actually made during healing (not scar tissue)

Question 6

7. Describe the 6 steps involved in indirect healing of a fracture.

Answer 6

1. A clot forms in the medullary cavity, under the periosteum, and between the ends of the bone fragments.
   . Adjacent bone tissue dies (necrosis) because the torn blood vessels are unable to perform exchange of nutrients/waste, gases to site.
2. This stimulates inflammation (vasodilation, infiltration of plasma, WBC, growth factors and mast cells)
3. Phagocytic cells move in and remove dead tissue. Fibroblasts and chondroblasts also arrive and lay down collagen fibers and cartilage, respectively on the network formed by the fibrin of the clot. This forms an initial bridge (fibrocartilaginous callus = procallus) between the bone ends.
   Osteoblasts within the procallus (from the periosteum and endosteum) synthesize collagen and matrix, which then calcifies, forming a bony callus (3).
4. During subsequent months, the callus is remodelled (4) by osteoblasts and osteoclasts (excess callus is resorbed and trabeculae are formed along lines of stress)

Question 7

8. Define dislocation and subluxation and where these are most likely to occur.

Answer 7

Displacement of one or more bones in a joint in which opposing surfaces lose all contact
Most often joints of the shoulder (most often), elbow, wrist, finger, hip and knee
Subluxation (981)
Displacement of one or more bones in a joint in which opposing surfaces lose only some contact
Same joints as above

Question 8

9. Define kyphosis, lordosis and scoliosis and name one cause for each.

Answer 8

Kyphosis (992)
Increased curvature of upper spine
Brought about through diseases causing loss of bone density in vertebrae (osteoarthritis, etc.) or fusion of joints between vertebrae (ankylosing spondylitis, etc.)
Lordosis (1004)
Loss of curvature of lower spine
Brought about through anyklosing spondylitis, for e.g.
Scoliosis (1029)
Rotational curvature of the spine
Can be idiopathic (perhaps genetic), due to systemic conditions (cerebral palsy), conditions not directly affecting spine (leg length discrepancy), etc.

Question 9

10. Define sprain, avulsion and strain and where these are most likely to occur.

Answer 9

Sprain (982)
Tearing of ligament.
Most common in wrist, ankle, elbow and knee
Complete separation commonly seen in young athletes is called an avulsion.

Strain (982)
Tearing or stretching of a muscle or tendon
Can occur anywhere in body, but most common in leg, hand, upper arm.

Question 10

11. Define osteoporosis, and the general process that leads to this condition.

Answer 10

Decrease in bone mass, leading to fragile bones
Can be present for decades – not known until fracture occurs
Not always a disease of age (some elderly people do not have it)
General process is that old bone is being reabsorbed faster than new bone is being deposited, resulting in bones losing density (thinner and more porous)
Eventually fractures can occur spontaneously
Appears to be most severe in femoral neck, thoracic and lumbar spine, and wrist

Question 11

12. Name 4 hormones that can affect bone density and how their influence is possible.

Answer 11

Plasma concentrations of calcium and phosphate determine mineral content of bone. Plasma concentrations are under control of several hormones, including PTH, cortisol, thyroid hormone and growth hormone.

Question 12

13. At what age does peak bone mass occur?

Answer 12

Peak bone mass occurs at around age 30, and then declines (resorption slowly exceeds formation).

Question 13

14. What hormone is linked to post-menopausal osteoporosis, and what is one effect of this hormone that affects bone density?

Answer 13

In women, bone mass decline is fastest in several years after menopause.
Numerous effects due to advanced age, but this type of osteoporosis is also linked to estrogen deficiency.
Estrogen deficiency can also arise through stress, excessive exercise and low body weight. (estrogen effects than therefore occur with younger women)
One effect of estrogen is that it aids in maintaining bone density through helping osteoclast apoptosis, so a decrease in estrogen results in more survival of bone resorbing cells

Question 14

15. Describe two differences between men and women that result in men developing osteoporosis later in life.

Answer 14

Differences between men and women:
The decrease in bone protecting hormones (testosterone, estrogen) in men is more gradual than in women, so that there is slower loss of bone in men than women during aging.
Men also begin with denser bones, so osteoporotic levels are reached at an older age.

Question 15

16. What are 4 risk factors associated with osteoporosis?

Answer 15

Low levels of androgens
Insufficient intake/absorption of minerals (calcium absorption decreases with age)
Excessive intake of caffeine, posphorus, alcohol and nicotine
Small stature / thin build

Question 16

17. Name 3 clinical manifestations of osteoporosis

Answer 16

Depends upon which bones are involved
Kyphosis: hunched back due to vertebral collapse
Fractures very common due to thin and sparse trabeculae in spongy bone and porous compact bone.
Fractures of long bones (particularly the femur, especially the neck: “broken hip”), radius, ribs and vertebrae are most common.
Fatal complications of fractures include fat or pulmonary embolism, pneumonia, hemorrhage and shock.

Question 17

18. What is osteomyelitis?
19. Describe two types of osteomyelitis and one source for each.
20. What is the primary causative organism for osteomyelitis?

Answer 17

Infectious bone disease
Exogenous osteomyelitis - most common. Caused by pathogens entering joint (fractures, penetrating wounds (bites), surgery) (e.g., diabetic foot infection).
In endogenous osteomyelitis, pathogens are carried in the blood from site of infection elsewhere in the body. (e.g., hematogenous osteomyelitis, usually found in infants, children and elderly).
Primary causative organism is Staphylococcus aureus, but other bacteria, fungi, parasites and viuses can also cause bone infection.

Question 18

21. Describe the sequence of events that can occur in children and adults upon infection causing osteomyelitis.

Answer 18

Sequence of events upon infection:
Intense inflammatory response (vascular engorgement, edema, leukocyte activity, abscess formation)
In children, exudate from infection can lift off periosteum, thereby disrupting blood supply to area of the bone = necrosis of area (sequestrum).
Lifting of periosteum stimulates osteoblasts, which lay down layer of bone on top of sequestrum (involucrum)
In adults, periosteum is more firmly attached to bone, so exudate does not cause this problem. Instead, it can disrupt and weaken the cortex, increasing susceptibility to fracture.

Question 19

22. Where in the body does osteoarthritis usually occur?

Answer 19

Age-related disorder of synovial joints.
Characterized by local areas of loss of articular cartilage, new bone formation of joint marginms (osteophytosis), subchondral bone changes, variable degrees of mild synovitis and thickening of the joint capsule.
Usually in hands, hips or spine
Prevalence increases with age.

Question 20

23. What is the primary defect in osteoarthritis?

Answer 20

The primary defect is loss of articular cartilage.

Question 21

24. Describe the sequence of events in the development of osteoarthritis.

Answer 21

Early in disease, articular cartilage changes structure; the surface flakes off and underlying layers develop cracks.
Exposed articular bone becomes hardened and may develop cysts.
Cartilage coated projections of bone at the edges of the joint (osteophytes) may grow out and alter the anatomy of the joint.
Small pieces of these projections may break off (joint mice) and go into the synovial cavity.
If the synovial membrane is irritated by these, synovitis and joint effusion develop.
The joint capsule becomes thickened and may stick to the underlying bone, therefore restricting movement.

Question 22

25. Name 4 clinical manifestations of osteoarthritis.

26. Describe two causes for the enlargement (swelling) of the joints in osteoarthritis.

Answer 22

Appear during the 5th or 6th decade of life.
Pain in one or more joints (heavy use, load bearing)
Primary signs include pain, stiffness, enlargement (swelling), deformity of joints
Stiffness is usually only in first few minutes of use (uncommon to persist after 30 min)
Enlargement (swelling) due to bone enlargement around the joint
Swelling may also be due to inflammatory exudate or blood entering the joint cavity, thereby increasing the volume of synovial fluid (= “joint effusion”), caused by presence of bone fragments in the synovial cavity, drainage of cysts, etc.
Range of motion is limited due to cartilage degeneration. Movement often accompanied by creaking or grating sounds.

Question 23

27. What is inflammatory joint disease characterized by?

Answer 23

Characterized by inflammatory damage in the synovial membrane or articular cartilage and by systemic signs of inflammation (fever, leukocytosis, malaise, anorexia)

Question 24

28. Define rheumatoid arthritis.

Answer 24

Chronic, systemic, inflammatory autoimmune disease distinguished by joint swelling and tenderness and destruction of synovial joint leading to disability and premature death.
The first tissue affected is the synovial membrane, followed by the articular cartilage, joint capsule and surrounding tissue.
Most commonly affected are fingers, wrists, elbows, feet, ankles, knees
Cause is unknown, but probably due to interaction of genetic factors with inflammatory mediators.
Involves the production of antibodies (specifically termed “rheumatoid factors” RFs) that react to portions of host antibodies present in the synovial membrane.

Question 25

29. Describe the development of rheumatoid arthritis at the cellular level.
30. What is an RF factor in the development of rheumatoid arthritis?

Answer 25

An unknown antigen in the synovial tissue triggers the immune system, activating T cells, B cells and macrophages. One result is B cells that produce antibodies against the Fc portion of IgG. These antibodies (RF factors) form complexes with the IgG, and activate complement protein, which further stimulates the immune response.
A dense population of immune cells and the resultant large production of cytokines stimulate edema and production of granulation tissue.
The granulation tissue produces a tissue called “pannus”, which consists of lymphocytes, macrophages, fibroblasts and mast cells.
Pannus can grow over and erode articular cartilage and bone, expanding and destroying the joint.

Question 26

31. Name 3 clinical manifestations of rheumatoid arthritis that are different from osteoarthritis.

Answer 26

RA begins with general systemic manifestations of inflammation: fever, fatigue, weakness, etc.
Joints become painful, tender and stiff.
Stiffness lasts for about 1 hour after rising
Initial joints affected are those in the hands and wrists.
Loss of range of motion can progress to deformities (e.g., ulnar deviation of the hands)
Loss of mobility leads to atrophy of surrounding muscles.

Question 27

32. What is ankylosing spondylitis characterized by?
33. How does ankylosing spondylitis differ from rheumatoid arthritis?
34. Describe the development of ankylosing spondylitis.

Answer 27

Chronic inflammatory joint disease characterized by:
Ankylosing – stiffening and fusion of the spine and sacroiliac joints.
Spondylitis – systemic, autoimmune inflammatory disease

Differs from rheumatoid arthritis in area that is affected:
In AS, excessive bone formation occurs at the point at which ligaments, tendons and the joint capsule are inserted into bone, leading to fusion of the joint, primarily the sacroiliac joint and the vertebral column.
In RA, the primary site of inflammation is the synovial membrane, thus affecting synovial joints
Fibrocartilage in vertebral joints becomes inflamed.

Damage occurs from macrophages and lymphocytes.

Fibroblasts repair the damage, secreting collagen that eventually becomes ossified.

Final result is fusion of the joints.

Primary AS primarily affects men between 15-40 yrs.

Question 28

35. Define equinovarus.

36. Define developmental dyspasia of the hip.

Answer 28

One or both feet turn inward and downward
Can be positional, idiopathic or as a result of another syndrome (e.g., spina bifida)
Can be corrected by manipulation and casing begun soon after birth
Imperfect development of the hip joint.
May be idiopathic or teratologic (attributable to another cause, e.g., spina bifida)