Bone and Joint Infections — MCQs
Osteomyelitis of spine is caused by the most common organism?
A boy presented with multiple non suppurative osteomyelitis with sickle cell anaemia. What will be the causative organism?
A most common cause of nongonococcal septic arthritis is
What is the most common sequela of tuberculous spondylitis in an adolescent?
Which of the following statements about osteomyelitis is incorrect?
In acute septic arthritis of hip in children, which finding indicates poor prognosis?
All are features of septic arthritis except:
A 10 year old child came to the OPD with pain and mass in right lumbar region with no fever, with right hip flexed. The pain increased on extension and X ray showed spine changes. Most probable diagnosis is:
Radiographically, the lesion shown in the image could be:
The joint that permits nodding of the head while saying "yes" is:
Bone and Joint Infections Indian Medical PG Practice Questions and MCQs
Question 1: Osteomyelitis of spine is caused by the most common organism?
- A. Streptococcus
- B. Pseudomonas
- C. Mycobacterium tuberculosis
- D. Staphylococcus aureus (Correct Answer)
Explanation: ***Staphylococcus aureus*** - **_Staphylococcus aureus_** is the most common causative organism for **hematogenous osteomyelitis** in adults, including osteomyelitis of the spine. - It frequently gains access to bone through the bloodstream, leading to infection of the vertebral bodies. *Streptococcus* - While various species of **_Streptococcus_** can cause bone infections, they are **less common** than **_Staphylococcus aureus_** in vertebral osteomyelitis. - **Group A Streptococcus** primarily causes soft tissue infections, and **_S. pneumoniae_** is more associated with pneumonia and meningitis. *Pseudomonas* - **_Pseudomonas aeruginosa_** is a common cause of osteomyelitis, particularly in specific risk groups such as intravenous drug users, patients with puncture wounds (especially through footwear), or those with implanted medical devices. - It is **not the most common** overall cause of general osteomyelitis of the spine. *Mycobacterium tuberculosis* - **_Mycobacterium tuberculosis_** causes tuberculous spondylitis **(Pott's disease)**, which commonly affects the spine, leading to characteristic vertebral destruction and kyphosis. - While significant globally, it is **not the most common bacterial cause** of acute pyogenic vertebral osteomyelitis.
Question 2: A boy presented with multiple non suppurative osteomyelitis with sickle cell anaemia. What will be the causative organism?
- A. Salmonella (Correct Answer)
- B. H. influenzae
- C. Enterobacter species
- D. Staphylococcus aureus
Explanation: ***Salmonella*** - **Salmonella species** are a well-known cause of **osteomyelitis** in patients with **sickle cell anemia**, due to factors like gut mucosal damage and functional asplenia. [1] - The unique pathophysiology of sickle cell disease, including areas of bone infarction and compromised reticulendothelial system function, predisposes these patients to **Salmonella infections**. [1] *Staphylococcus aureus* - While **Staphylococcus aureus** is the most common cause of osteomyelitis in the general population, it is less likely to be the causative organism in patients with **sickle cell anemia** compared to Salmonella. - Its presence usually indicates other predisposing factors like trauma or prosthetic devices. *H. influenzae* - **Haemophilus influenzae** was a common cause of osteomyelitis in children before widespread vaccination but is now rare, especially with routine immunizations. - It is not specifically associated with a higher risk in patients with **sickle cell disease** for osteomyelitis compared to other pathogens. *Enterobacter species* - **Enterobacter species** can cause osteomyelitis, particularly in immunocompromised individuals or following surgery, but they are not uniquely associated with **sickle cell anemia** as a primary cause compared to Salmonella. - Their involvement in non-suppurative osteomyelitis in this specific patient population is less common.
Question 3: A most common cause of nongonococcal septic arthritis is
- A. Staphylococcus aureus (Correct Answer)
- B. Pseudomonas aeruginosa
- C. Streptococcus species
- D. Haemophilus influenzae
Explanation: ***Staphylococcus aureus*** - **_Staphylococcus aureus_** is the most common cause of **nongonococcal septic arthritis** in adults and children [1]. - This organism can invade joints via **hematogenous spread** or direct inoculation following trauma or surgery [1]. *Pseudomonas aeruginosa* - **_Pseudomonas aeruginosa_** is a common cause of septic arthritis in **IV drug users** and individuals with **puncture wounds** through shoes [1]. - It is not the most common overall cause of nongonococcal septic arthritis. *Streptococcus species* - Various **_Streptococcus species_** (e.g., *S. pyogenes*, *S. pneumoniae*) can cause septic arthritis, particularly in elderly individuals or those with underlying conditions [1]. - However, they are **less frequent** causes compared to *Staphylococcus aureus* [1]. *Haemophilus influenzae* - **_Haemophilus influenzae_** was a common cause of septic arthritis in **children** before the widespread introduction of the hib vaccine. - Its incidence has significantly decreased in vaccinated populations and is now rare in adults.
Question 4: What is the most common sequela of tuberculous spondylitis in an adolescent?
- A. Fibrous Ankylosis
- B. Pathological dislocation
- C. Chronic osteomyelitis
- D. Bony ankylosis (Correct Answer)
Explanation: ***Bony ankylosis*** - **Bony ankylosis** is a frequent outcome in successfully treated tuberculous spondylitis, particularly in adolescents due to their growth potential and robust healing responses. - The inflammatory process and subsequent healing, including bone repair, can lead to the fusion of vertebral bodies as the body attempts to stabilize the affected spinal segment. *Fibrous Ankylosis* - While **fibrous ankylosis** can occur, it's typically an earlier or less complete form of healing compared to bony ankylosis in the context of tuberculosis, which often leads to more extensive bone destruction and repair. - In adolescents, where osteoblastic activity is high, the body often progresses to a more stable bony fusion rather than a fibrous one. *Pathological dislocation* - **Pathological dislocation** is a severe complication that can occur due to extensive bone destruction and vertebral collapse, but it is not the most common sequela after treatment, especially with modern management. - Dislocation implies a loss of alignment and potentially severe neurological deficits, which are rarer than the healing process itself leading to fusion. *Chronic osteomyelitis* - **Chronic osteomyelitis** refers to persistent infection and inflammation within the bone. While tuberculous spondylitis is a form of osteomyelitis, if successfully treated, the infection is resolved, and the sequelae are related to the healing process itself (like ankylosis), not ongoing infection. - The question asks for the most common *sequela* (consequence of the disease or its treatment), assuming the infection has been managed.
Question 5: Which of the following statements about osteomyelitis is incorrect?
- A. Sequestrum is a piece of dead bone
- B. Epiphysis most commonly involved region (Correct Answer)
- C. In sickle cell anemia salmonella is causative organism
- D. Involucrum is dense sclerotic bone overlying a sequestrum
Explanation: ***Epiphysis most commonly involved region*** - This statement is **incorrect** because osteomyelitis, particularly in children and adolescents, most commonly affects the **metaphysis** of long bones due to its rich, slow-flowing blood supply, which facilitates bacterial deposition. - The epiphysis is less commonly involved primarily due to the differences in vascularity and growth plate anatomy. *Sequestrum is a piece of dead bone* - This statement is **correct**. A **sequestrum** refers to a piece of dead or necrotic bone that has separated from the surrounding healthy bone, often seen in chronic osteomyelitis [1]. - It results from the inflammatory process and lack of blood supply, acting as a nidus for infection. *Involucrum is dense sclerotic bone overlying a sequestrum* - This statement is **correct**. An **involucrum** is a new shell of dense, sclerotic bone that forms around a sequestrum in chronic osteomyelitis, attempting to wall off the infection [1]. - It represents the body's attempt to heal and contain the infection, often leading to sinus tract formation [1]. *In sickle cell anemia salmonella is causative organism* - This statement is **correct**. Patients with **sickle cell anemia** are particularly susceptible to **Salmonella osteomyelitis**, which replaces Staphylococcus aureus as the predominant causative agent in this population. - The altered splenic function and compromised immune response in sickle cell disease contribute to this increased risk. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Bones, Joints, and Soft Tissue Tumors, pp. 1197-1198.
Question 6: In acute septic arthritis of hip in children, which finding indicates poor prognosis?
- A. Age <2 years
- B. Delay in Treatment >48 hours (Correct Answer)
- C. Elevated CRP
- D. Gram Negative Infection
Explanation: ***Delay in Treatment >48 hours*** - A delay in treatment of **acute septic hip arthritis** beyond 48 hours significantly increases the risk of irreversible cartilage damage and long-term functional impairment due to sustained inflammatory and enzymatic degradation. - This delay can lead to more severe joint destruction, avascular necrosis of the femoral head, and post-infectious osteoarthritis, all contributing to a **poor prognosis**. *Age <2 years* - While younger children can have more subtle symptoms and a higher risk of diagnostic delay, age itself is not the most determinant factor for poor prognosis compared to treatment delay. - Management in this age group focuses on early diagnosis and aggressive treatment to prevent growth plate damage. *Elevated CRP* - **Elevated C-reactive protein (CRP)** is a common finding in acute septic arthritis, indicating systemic inflammation and the severity of infection. - While reflecting disease activity, an elevated CRP alone does not directly indicate poor prognosis as it typically responds well to appropriate antibiotic treatment and surgical drainage. *Gram Negative Infection* - Gram-negative infections can be more challenging to treat and may require specific antibiotic regimens, but the type of organism is generally less critical than the **duration of untreated infection** in determining long-term outcomes. - With prompt and appropriate therapy, many gram-negative infections can be successfully managed without causing poor long-term outcomes.
Question 7: All are features of septic arthritis except:
- A. Joint swelling
- B. Symmetric joint involvement (Correct Answer)
- C. Painful joint movement
- D. Elevated ESR
Explanation: Symmetric joint involvement - Septic arthritis typically presents as a monoarticular condition [1], affecting a single joint, or sometimes a few joints in an asymmetric pattern. - Symmetrical joint involvement is more characteristic of inflammatory arthropathies like rheumatoid arthritis, not septic arthritis [1]. Joint swelling - Inflammation and the accumulation of effusion in the joint capsule due to infection commonly lead to noticeable joint swelling. - This is a hallmark symptom as the body responds to bacterial invasion within the joint space. Painful joint movement - The acute inflammatory process and distension of the joint capsule by infection cause significant pain with any movement or weight-bearing. - Patients often present with an unwillingness to move the affected joint, characteristic of a "pseudoparalysis". Elevated ESR - Erythrocyte sedimentation rate (ESR) is a general marker of inflammation and is typically significantly elevated in septic arthritis due to the systemic inflammatory response to infection. - This indicator helps confirm the presence of an active inflammatory process, though it is not specific to septic arthritis.
Question 8: A 10 year old child came to the OPD with pain and mass in right lumbar region with no fever, with right hip flexed. The pain increased on extension and X ray showed spine changes. Most probable diagnosis is:
- A. Appendicular lump in retrocecal position
- B. Pyonephrosis
- C. Psoas abscess (Correct Answer)
- D. Torsion of Right undescended testis
Explanation: ***Psoas abscess*** - A **psoas abscess** can present as a lumbar mass with pain, and the classic **psoas sign** (pain on hip extension) occurs because the inflamed psoas muscle is stretched. Spine changes on X-ray suggest a potential vertebral source, such as **spinal tuberculosis (Pott's disease)**, which is a common cause of psoas abscess in children. - The absence of fever does not rule out chronic infections like tuberculosis, and the **flexed hip posture** is a common compensatory mechanism to relieve tension on the inflamed psoas muscle. *Appendicular lump in retrocecal position* - While a retrocecal appendicular lump can cause a right lumbar mass, the pain would typically worsen with hip flexion, not extension, and it is less likely to be associated with **spine changes** on X-ray. - Appendicular lumps are usually accompanied by a history of appendicitis with pain that is often more diffuse in the right lower quadrant, and may be associated with **fever and leukocytosis**. *Pyonephrosis* - **Pyonephrosis** (pus in the kidney) would typically present with significant systemic symptoms of infection, such as **fever, chills, and flank pain**. - While it can cause a flank mass, the characteristic **hip flexion and pain on extension (psoas sign)**, along with spine changes, are not typical features. *Torsion of Right undescended testis* - **Testicular torsion** presents with sudden, severe scrotal pain (or inguinal/pelvic pain if undescended) and swelling, not a lumbar mass or psoas signs. - It would also not be associated with **spine changes** on an X-ray.
Question 9: Radiographically, the lesion shown in the image could be:
- A. Cherubism
- B. Garre's osteomyelitis (Correct Answer)
- C. Fibrous dysplasia
- D. Osteosarcoma
Explanation: ***Garre's osteomyelitis*** - The radiographs show **periosteal new bone formation** resembling an **"onion skin"** appearance, which is characteristic of **Garre's osteomyelitis** (chronic osteomyelitis with proliferative periostitis). - This condition is typically a **reaction to low-grade chronic infection** or irritation, often seen in the periosteum of the mandible. *Cherubism* - Cherubism is a **fibro-osseous lesion** characterized by bilateral, symmetric enlargement of the jaws, giving a "cherubic" appearance. - Radiographically, it presents as **multilocular radiolucencies** with poorly defined borders, usually in children. *Fibrous dysplasia* - Fibrous dysplasia is a developmental anomaly where normal bone is replaced by **fibrous tissue and immature bone**. - Radiographically, it often has a **"ground glass" appearance** or a "peau d'orange" texture, differentiating it from the periosteal reaction seen in the image. *Osteosarcoma* - Osteosarcoma is a **malignant bone tumor** that typically shows a mix of osteolytic and osteoblastic areas, often with a **"sunburst" or "spiculated" periosteal reaction**. - While it involves periosteal reaction, the pattern and typical aggressive nature differ from the more layered and milder appearance of Garre's osteomyelitis.
Question 10: The joint that permits nodding of the head while saying "yes" is:
- A. Atlanto-axial joint
- B. Atlanto-occipital joint (Correct Answer)
- C. C2-C3 joint
- D. C3-C4 joint
Explanation: The joint that permits nodding of the head while saying "yes" is: ***Atlanto-occipital joint*** - This joint is formed by the **articulation** of the **superior articular facets** of the atlas (C1 vertebra) with the **occipital condyles** of the skull. - It is a **condyloid joint** that primarily permits flexion and extension, which are the main movements involved in nodding the head to say "yes." *Atlanto-axial joint* - This joint is located between the **atlas (C1)** and the **axis (C2)** vertebrae and is primarily responsible for the rotation of the head, as in shaking the head "no." [1] - It consists of three separate articulations: two **lateral atlanto-axial joints** and one **median atlanto-axial joint**, which is a pivot joint. *C2-C3 joint* - This refers to a typical **intervertebral joint** between the second and third cervical vertebrae. - These joints are **symphyses** formed by an **intervertebral disc** and allow for limited movements such as flexion, extension, lateral flexion, and rotation within the cervical spine segment, but not the primary "yes" motion. *C3-C4 joint* - Similar to the C2-C3 joint, this is an **intervertebral joint** between the third and fourth cervical vertebrae. - Its structure and function are consistent with other typical cervical intervertebral joints, allowing for general cervical spine movements rather than specific head nodding.
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