Bones and joints Flashcards
Which of the following is a disturbance of bone mineralisation?
A Paget’s disease
B Rickets
C Osteoporosis
D Hypertrophic pulmonary osteoarthropathy (HPOA)
B
Explanation
Rickets: defect in matrix mineralization, most often due to vitamin D deficiency or vitamin metabolism.
Osteoporosis: increased porosity of the skeleton due to reduced bone mass.
Paget’s Disease: osteoclastic bone activity and hectic bone formation.
Hypertrophic pulmonary osteoarthropathy (HPOA): paraneoplastic
Regarding myositis ossificans in skeletal muscle, which of the following statements is INCORRECT?
A Resembles osteosarcoma in the elderly
B Follows resolution of a muscle tear
C Does not resemble normal bone
D Is painless from the start of the disease
D
Explanation
In 50% of cases, myositis ossificans follows an episode of trauma (muscle tears) in young adults. It does not resemble normal bone. It does resemble an osteosarcoma in the elderly and must be distinguished from extraskeletal osteosarcoma. It is metaplastic bone- however, this type of metaplasia is less clearly seen as an adaptive response (rather a response form tissue injury) It is initially painful but becomes painless after a while. It is best to wait 6-12months to allow for full bone maturation before surgical excision, otherwise it may reoccur.
Note: it is a pathological-metaplastic process. But metaplasia is where one type differentiated cell type is replaced by another cell type. The cell types are still normal cells just adapting to the environment.
Which of the following statements is correct regarding osteomalacia?
A There is decreased Ca absorption from gut
B It is associated with decreased parathyroid hormone (PTH)
C It is associated with decreased osteoid matrix deposition
D It is caused by a 1,25(OH)2DH3-calciferol deficiency
D
Explanation
Osteomalacia results FROM hypocalcaemia. Parathyroid hormone (PTH) production is increased, which
- Activates renal alpha hydroxylase, thus increasing the amount of active vitamin D and calcium absorption (from gut)
- Mobilizes calcium form bone
- Decreases renal calcium excretion
- Increases renal excretion of phosphate.
Thus the serum calcium level is restored to near normal but hypophosphataemia is present so bone mineralization is impaired. There is an increase in osteoid matrix deposition in this condition
Regarding bacterial septic arthritis
A The different causative organisms affects men and women equally
B The main causative organism in adults is gonococcus
C The joint most affected in non-gonococcal septic arthritis is the knee
D Joints are affected more commonly by direct inoculation
C
Explanation
In bacterial septic arthritis the bacteria usually seed the joint during an episode of bacteraemia. Joints can become infected by direct inoculation or from contiguous spread from a soft tissue abscess or focus of osteomyelitis. H. influenza arthritis predominates in children <2yrs. Staph is the main causative agent in older children and adults. Gonococcus is prevalent during late adolescence and young adulthood. Those with sickle cell anaemia are prone to infection with SALMONELLA at any age. These joint infections affect the sexes equally except for gonococcus which is seen mainly in sexually active women. In 90% of non-gonococcal cases, the infection involves only a single joint, usually the knee followed in frequency by the hip, shoulder, elbow, wrist and sternoclavicular joints.
Note: the wording of the textbook is confusing: late adolescence and young adulthood- a web search gives this age 18-24yrs. Older children and adults- overlaps the 18-24 age bracket as well. The wording however, comes directly from the textbook.
I think that the stem which says “The main causative organism in adults is gonococcus” is incorrect because it should say YOUNG adults
Which of the following is true regarding Osteomyelitis?
A The metaphysis is the common site of infection in children
B In 30% of acute cases fail to resolve with drainage and antibiotics
C In 70% of cases, no organism is found
D Staph Aureus is usually the causative organism in neonates
A
Explanation
All types of organisms including bacteria, viruses, fungi and parasites can produce osteomyelitis. Pyogenic osteomyelitis is most often caused by bacteria. Organisms reach the bone via haematogenous spread, extension from a contiguous site and direct implantation. Staph. aureus is responsible for 80-90% of cases of pyogenic osteomyelitis. IVDU and patients with genitourinary tract infections often have E.Coli, Pseudomonas and Klebsiella as the causative organisms. In the neonatal period, H.influenzae and group B streptococci are most commonly found and in sickle cell disease, salmonella in prevalent. However in 50% of cases there are no causative organisms found. The location of infection in the long bone varies with age due to the osseous vascular circulation. In the neonate, the metaphysis and epiphysis are the main sites, whereas in children it is the metaphysis and in adults the epiphysis and subchondral regions. 5-25%of acute cases fail to resolve with drainage and antibiotics, and go onto chronic infection.
With regard to rheumatoid arthritis (RA), which of the following is CORRECT?
A In the joint it is confined to the synovium and does not involve the articular cartilage
B Caseous necrosis is typical of rheumatoid nodules
C It is confined to joints and skin
D Xrays of joints reveal articular marginal erosions
E There is decreased vascularity in the pannus
D
Explanation
Radiology finding in RA: Initially, joint spaces in the small joints of the hands show widening as a result of effusion; however, with cartilage destruction, joint spaces narrow. Erosions usually begin at the bare area of the joint not covered by cartilage, such as the intracapsular articular margins. Marginal erosions occur as a result of direct mechanical action of the hypertrophied synovium and granulation tissue.
Pannus formation: a vascularised mass of synovium and synovial stroma containing inflammatory cells, granulation tissue and synovial fibroblasts which grows over the articular cartilage and causes its erosion. In time, after the cartilage has been destroyed , the pannus bridges the apposing bone to form an ankylosis, which eventually ossifies and results in bony ankylosis.
Rheumatoid nodules are firm, non tender and contain a central zone of fibrinoid necrosis surrounded by epitheloid histocytes, lymphocytes and plasma cells.
RA is a chronic systemic inflammatory disorder that may affect many tissues and organs-skin, joints, blood vessels, heart, lung and muscles
In osteoarthritis, whichof the following ststements is CORRECT?
A The knees and hands are more commonly affected in men and the hips in women
B Osteophytes develop on top of the articular surface
C Chrondrocytes play a role in cartilage destruction
D Characteristic symptoms include deep, achy pain that improves with use
E There is a marked synovial reaction
C
Explanation
Osteoarthriits implies an inflammatory disease however, even though the inflammatory cells may be present , OA is considered to be an intrinsic disease of cartilage in which biochemical and metabolic alterations in individuals with genetic susceptibility result in its breakdown
The mechanisms leading to OA are unclear, but chondrocytes are at the centre of the disease process, which can be divided into several processes
1-chondrocyte injury, which is related to genetic, ageing and biochemical factors
2- Early OA in which chondrocytes proliferate and secrete inflammatory mediators, collagens, proteoglycans, proteases, which act together to remodel the cartilaginous matrix and initiate secondary inflammatory changes in the synovium and subchondral bone
3- Late OA, repetitive injury results in chondrocyte dropout, marked loss of cartilage and extensive subchondrol bone damage
Morphology: The synovium is usually only mildly congested and fibrotic, and may have scattered inflammatory cells. Bony osteophytes (outgrowths) develop at the margins of the articular surface.
In most cases OA appears insidiously, without apparent cause. The disease is usually oligoarticular but may be generalised. Patients with primary disease are often asymptomatic until they are in there 50s. Gender has some influence on distribution. The knees and hands are more commonly affected in women and the hips in men
Characteristic symptoms include deep, achy pain that worsens with use, morning stiffness, crepitus and limited range of movement
The MOST common cause of infectious arthritis in young adults is?
A N. gonorrhoeae
B S. pneumoniae
C Salmonella
D S. aureus
E H. influenza
D
Explanation
H-influenza arthritis predominates in children under 2yrs.
S-aureus is the main causative agent in older children and adults. More common to be monoarticular.(90% of cases).
N-gonococcus is prevalent during late adolescents and young adult hood. More common to be polyarticular.
Salmonella is prevalent in any age individuals prone to sickle cell anaemia.
Both sexes are equally involved, except when the agent is gonococcus-affects women more.
Uptodate reports that staf-aureus is the most common cause of bacterial arthritis detected by culture in ALL AGE GROUPS
Note: the wording of the textbook is confusing: late adolescence and young adulthood- a web search gives this age 18-24yrs. Older children and adults- overlaps the 18-24 age bracket as well.
What percentage of bone must be lost in osteoporosis before changes are visible on X-ray?
A 35%
B 15%
C 25%
D 45%
A
Explanation
Osteoporosis cannot be reliably identified on standard radiograms until 30-40% of bone mass has been lost.
Infection of which bursa of the knee joint can quickly spread to involve the knee joint?
A Prepatellar
B Suprapatellar
C Infrapatellar
D Popliteal fossa
B
Explanation
The suprapatellar bursa lies deep to the quadriceps tendon and communicates with the knee joint
What is the most common detected cause of pyogenic osteomyelitis?
A E. Coli
B S. aureus
C Streptococcus pyogenes
D Pseudomonas Aeruginosa
B
Explanation
Pyogenic osteomyelitis is almost always caused by bacterial infections. Organisms may reach the bone by (1) hematogenous spread, (2) extension from a contiguous site, and (3) direct implantation. Staphylococcus aureus is responsible for 80% to 90% of the cases of culture-positive pyogenic osteomyelitis.
A 24-year-old man is suspected of having osteomyelitis of his left femur. He admits to intravenous drug use. Which is the most likely responsible organism?
A E. Coli
B S. aureus
C Streptococcus pyogenes
D Pseudomonas Aeruginosa
A
Explanation
IVDU are more susceptible to gram negative organisms as a cause of osteomyelitis as well as other common infections.
Note-explanation form a similar MCQ about osteomyelitis.: “Staphylococcus aureus is responsible for 80% to 90% of the cases of culture-positive pyogenic osteomyelitis. These organisms express cell wall proteins that bind to bone matrix components such as collagen, which facilitates adherence of the bacteria to bone. Escherichia coli, Pseudomonas, and Klebsiella are more frequently isolated from individuals with genitourinary tract infections or who are intravenous drug abusers” direct from TB. The following is suggested: This could be interpreted differently; when E. coli is isolated, it is more likely to be from an IVDU or a person with a UTI. That doesn’t mean IVDU’s are more likely to have E. coli osteomyelitis. Good thought but hard to know the intensions of the MCQ writers.
More issues about this question from users:
Escherichia coli, Pseudomonas, and Klebsiella are more frequently isolated from individuals with genitourinary tract infections or who are intravenous drug abusers” - note uses the word ‘MORE frequently’. The questions states ‘most frequently’. The answer is therefore staph aureus.
What condition is commonly associated with Heberden’s nodes?
A Sjorgen’s diease
B Osteoarthritis
C Psoriasis
D Rheumatoid arthritis
B
Explanation
A Heberden node describes a bony swelling of the distal interphalangeal finger joint. It is a sign of osteoarthritis, a degenerative joint disease.
A Bouchard node is a similar swelling affecting the proximal interphalangeal finger joint
Heberden and Bouchard nodes are equally common in males and females of all races.
They are common in older individuals. However, more than half of the patients with Heberden nodes and osteoarthritis are diagnosed before the age of 65 years.
Bouchard nodes are less common than Heberden nodes and are associated with more severe arthritis.
The presence of the nodes is strongly familial.
More than 60% of patients with osteoarthritis of the knees have Heberden nodes.
Source: https://dermnetnz.org/topics/heberden-bouchard-nodes/
What is the most important hormonal factor in the development of osteoporosis?
A Parathyroid hormone
B Oestrogen
C Progesterone
D Cortisol
B
Explanation
Estrogen deficiency plays the major role in postmenopausal osteoporosis and close to 40% of postmenopausal women are affected by osteoporosis. Decreased estrogen levels after menopause actually increase both bone resorption and formation but the latter does not keep up with the former, leading to high-turnover osteoporosis.
