O&T Past Paper Flashcards
Bacteriology of septic arthritis (common to uncommon)
- <2 years old
H. influenza, S. aureus
Strep. pneumoniae, E.coli
Strep. pyogene, Group B strep, Proteus, Pseudomonas
Nesseria meningitides
N. gonorrhoeae, Bacteroides
Bacteriology of septic arthritis (common to uncommon)
- Around 2 years old
S. aureus
S. pneumoniae, E. coli
Strep. pyogene, Group B strep, Proteus, Pseudomonas/ Haemophilus
Nesseria meningitides
N. gonorrhoeae, Bacteroides
Bacteriology of septic arthritis (common to uncommon)
- >2 years old
S. aureus*, S. pyogenes
S. pneumoniae, E. coli
Haemophilus, Proteus
Nesseria meningitides
N. gonorrhoeae, Bacteroides
Complications of septic arthritis
- Immediate
- Delayed
Immediate: systemic sepsis, death.
Delayed: premature OA, joint deformity/stiffness, closure of physeal plate and growth disturbance (leg length discrepancies), pathological fractures, chronic or persistent infection.
A baby girl of age 3 months old presented with decrease of movement of the left lower limb. She was a premature baby, born at 32 weeks of gestation, had history of multiple blood taking at femoral vein. There was fever and she refused to feed for 3 days. The baby screamed when her left knee was flexed.
What is the most likely cause of the problem?
Septic arthritis of left hip joint
Abnormalities on XR for septic arthritis?
Early (normal)
Delayed (soft tissue swelling, loss of tissue planes, widening of radiological joint space, slight subluxation (due to effusion))
Late (narrowing and irregularity of joint space, vertebral end-plate disruption)
What investigations would you order for septic arthritis apart from Xray?
Blood – CBC with differential, CRP/ESR
Blood for C/ST
Ultrasound – shows joint effusion
Arthrocentesis – for appearance, smear and culture, WBC (>50k/mm3), protein (high) ± glucose (low, <33% serum)
MRI – usually for occult joint arthritis (eg. SIJ, SCJ)
Treatment of 3 month baby with septic arthritis of hip?
1) Resuscitation and Maintain Vitals
2) IV Antibiotics:
Empirical broad-spectrum 3rd generation cephalosporin (eg. ceftriaxone) until C/ST available
→ then change to specific Abx
→ change to oral Abx when CRP normalize
3) Urgent Open or Arthroscopic Arthrotomy – joint decompression, drainage, lavage
A 30-year-old man with Hx of trauma and IVDU presented with low back pain for 1 week and low-grade fever.
L-spine X-ray: destruction in inferior border of L3 and superior border of L4
Groin region shows injection ‘holes’.
Give TWO possible causes for low back pain
Trauma causing herniated intervertebral disc;
Pyogenic spondylitis
Five investigations for IV addict, 30 year old man with lower back pain for 1 week with fever.
Blood – CBC with diff, ESR, CRP
Blood culture
MRI – for diagnosis and assessment of disease extent (eg. assessment of neurological involvement)
CT-guided biopsy – for C/ST and AFB smear/culture
(Bone scintigraphy) Gallium bone scan
Tests for TB – IGRA, tuberculin skin test
Two treatment options for IV addict, 30 year old man with lower back pain for 1 week with fever.
Conservative – Abx alone (3rd generation cephalosporin + aminoglycoside/quinolone for IVDU), IV until CRP normalizes then oral for 3mo
Surgery – if open Bx needed, decompression of clinically significant abscess
- Indications: failed medical Tx, neurological deficits or progressive deformity or instability
Which joints are commonly affected in rheumatoid arthritis?
Small joints – PIP, MCP, wrist Large joints – knee, ankle, elbow, shoulder Cervical spine (rheumatoid spondylitis)
Which joints are commonly affected in osteoarthritis?
Weight-bearing joints – hips, knees, C- and L-spine
Small hand joints – PIP, DIP, 1st MCP, trapezioscaphoid joint
Where does tennis elbow affect? (1)
Lateral epicondyle – affects extensor and stabilizer of wrist (extensor carpi radialis brevis)
Where does golfer elbow affect? (1)
Medial epicondyle – flexors and pronators of wrist
Name an “asymmetrical” arthritis and describe their difference in pattern of involvement in the fingers.
Psoriatic arthritis – swelling in PIPJ, deformities in DIPJ
Gout – most commonly affects 1st MTP but can affect other sites eg. DIP, PIP, wrist, knee, ankle…
What tendons are involved in De Quervain’s disease?
Extensor pollicis brevis and abductor pollicis longus
From what cells do carcinoma and sarcoma arise? (2)
Carcinoma from epithelial cells, sarcoma from mesenchymal (connective tissue) cells.
From what tissues does sarcoma arise? (5)
Sarcoma can arise from
- Bone (osteosarcoma)
- Muscles (leiomyosarcoma, rhabdomyosarcoma)
- Cartilage (chondrosarcoma)
- Vessels (angiosarcoma)
- Fat (liposarcoma)
What tissues most commonly give rise to sarcoma? (2)
Soft tissues (fat and smooth muscles).
e.g. Gastrointestinal Stromal Tumour (GIST) from smooth muscle
Some soft tissue tumours present very late because they are unnoticed until they are very large, due to their location. In what part of the body does such scenario commonly arise? (1)
GI tract
List some types of biopsy (4)
FNA, tru-cut, incisional open, excisional open
Who is responsible for taking biopsy for soft tissue tumour? (1)
Tumour specialists (Clinical Oncologists)
A 15-yo girl noticed pain over thigh associated with a firm mass above right knee for four months. There is night pain despite she is able to walk with a normal gait. She doesn’t have fever. The mass is fixed on the femur and is tender on palpation.
a) What are the possible diagnoses?
Osteosarcoma
Other malignancies – chondrosarcoma, Ewing’s sarcoma, lymphoma, metastasis
Benign mass – chondroblastoma, osteoblastoma
Non-neoplastic lesion – osteomyelitis, TB, eosinophilic granuloma, aneurysmal cyst
What investigations apart from X-ray are required to confirm the diagnosis of osteosarcoma?
- Plain radiograph (AP & lateral view) of Right knee:
Codman’s triangle
Soft tissue mass shows sunray pattern - MRI with contrast of the Right knee
- PET-CT to look for metastasis and for staging of cancer
- Trucut biopsy: presence of a malignant sarcomatous stroma, associated with the production of tumor osteoid and bone
After Ix by biopsy and imaging, what are the parameters that will determine the staging of osteosarcoma?
Staging of musculoskeletal tumour by Enneking’s staging system:
- Grading of tumour: Benign, Low / High grade
- Compartment of involvement of tumour: intracompartmental / extracompartmental
- Any presence of metastases
What is the plan of management for osteosarcoma
For localized primary osteosarcoma:
Surgery + neoadjuvant and adjuvant chemotherapy
A 30-year-old male patient presents with a progressively enlarging hard mass on the left thigh with no history of trauma and fever.
Name 2 likely diagnoses (2)
Osteosarcoma
Other malignant bone tumors (ie, Ewing’s sarcoma, chondrosarcoma, lymphoma, and metastases)
Benign bone tumors (eg, chondroblastoma, osteoblastoma)
Nonneoplastic conditions: osteomyelitis, eosinophilic granuloma, and aneurysmal bone cysts
Describe 3 abnormalities on X-ray of osteosarcoma of femur(3)
Bone:
(1) mixture of radiodense and radiolucent areas (mixed lytic and sclerotic appearance)
(2) Codman’s triangle (periosteal new bone formation)
Soft tissue
(1) Sunray pattern (ossified soft tissue mass)
Name 2 investigations for osteosarcoma of femur
PET-CT for metastasis and for staging
Trucut Biopsy – presence of malignant sarcomatous stroma, a/w production of tumour osteoid and bone
Name 2 management options of osteosarcoma of femur
Potential cure for localized primary osteosarcoma:
Complete excision with adjuvant chemotherapy
Palliative treatment for bone secondaries:
Control bone pain
Prevent pathological fractures and neurological deficits
By means of chemotherapy, hormonal therapy, target therapy and bisphosphonates
