Examqo › Examqo library › Orthopedic surgery › Bone and joint infection · IMLE
Osteomyelitis (bone infection)
Bone infection arrives through the blood (mainly in children and in the spine), by spread from a nearby focus (the diabetic foot) or after trauma and surgery; diagnosis rests on MRI and culture, and treatment combines prolonged antibiotics with surgery when there is pus or dead bone.
Why it matters in the exam
In children infection comes through the blood and settles in the metaphysis of a long bone because of slow flow in the vascular loops; the child presents with fever, local pain and refusal to use the limb. The usual organism is Staphylococcus aureus, including resistant strains, and in children under 4 Kingella kingae; in sickle cell disease think also of Salmonella, and in newborns of group B streptococcus and Gram-negative bacteria. Plain radiographs are normal for the first two weeks, so MRI is the test of choice; blood cultures are positive in about half of children. In children, antibiotics are given intravenously with an early switch to oral treatment when fever settles and CRP improves, for a total of about 3–4 weeks; surgery is needed for a subperiosteal abscess or lack of response. In adults, spinal infection, infection around implants and diabetic foot infection are more common: when the patient is stable, a biopsy for culture is preferable before antibiotics. Chronic osteomyelitis is marked by dead bone (sequestrum), new bone around it (involucrum) and a sinus tract; treatment is surgical removal of all dead bone and prolonged antibiotics, and a sinus that persists for years can turn into squamous cell carcinoma (Marjolin). A rapid fall in CRP is a good marker of treatment success and guides the decision to switch to oral treatment.
Key points
- In children: blood-borne infection that settles in the metaphysis.
- Staphylococcus aureus is common at all ages; Kingella in young children; Salmonella in sickle cell disease.
- MRI is the test of choice; radiographs lag by two weeks.
- In children — early oral switch, 3–4 weeks in total.
- Chronic disease: dead bone and a sinus tract — surgical debridement.
Summary table
| Situation | Common organisms | Diagnosis | Treatment |
|---|---|---|---|
| Acute osteomyelitis in a child | Staphylococcus aureus; Kingella under age 4 | MRI, blood cultures, CRP | Intravenous antibiotics with early oral switch, 3–4 weeks |
| Patient with sickle cell disease | Salmonella and Staphylococcus aureus | MRI and cultures | Cover both organisms |
| Vertebral infection in an adult | Staphylococcus aureus | MRI, blood cultures and CT-guided biopsy | Antibiotics for about 6 weeks; surgery for neurological deficit or instability |
| Diabetic foot | Mixed infection | Probe-to-bone test, MRI, bone biopsy | Debridement, antibiotics, offloading and treatment of ischaemia |
| Chronic osteomyelitis | Staphylococcus aureus, mixed infection | Dead bone, sinus tract, MRI and CT | Surgical debridement, soft tissue cover and prolonged antibiotics |
A free exam question
מה בדיקת הדימות המדויקת ביותר ובעלת ה- positive predictive value הגבוהה ביותר לאבחון של אוסטאומיליטיס כרוני באדם שטופל באופן חלקי באנטיביוטיקה? (the question as examined, in Hebrew)
- א. מיפוי עם תאי דם לבנים מסומנים בטכנציום 99 mTC
- ב. מיפוי עם תאי דם לבנים מסומנים באינדיום 111 In
- ג. חתכי STIR בבדיקת MRI
- ד. מיפוי FDG-PET
In the full version for subscribers
- A simple algorithm
- Memory aid
- Exam traps
- 5 review cards
- Enough for IMLE
The full version is open to subscribers of: Orthopedic surgery, Medical licensing exam (IMLE), Pediatrics, Internal medicine.
Subscriber? Read the full topic Plans and prices 25 free questions
Sources
- Lovell and Winter's Pediatric Orthopaedics, 8th ed. (2020) — Bone and Joint Sepsis
- IDSA Clinical Practice Guideline, 2015 — Native Vertebral Osteomyelitis in Adults
- Apley and Solomon's System of Orthopaedics and Trauma, 10th ed. (2017) — Infection
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.