Bone infection in the diabetic foot — diabetic foot osteomyelitis (DFO) — is one of the most challenging complications of diabetic foot disease. It is estimated to complicate roughly 20% of moderate and 50–60% of severe diabetic foot infections, and unrecognised or undertreated DFO is a leading driver of major lower-limb amputation. The 2023 update to the joint International Working Group on the Diabetic Foot and Infectious Diseases Society of America (IWGDF/IDSA) guidelines has refined how clinicians diagnose, sample, and treat this condition, with a clear shift toward shorter antibiotic courses, broader use of oral therapy, and targeted bone sampling.
Establishing the Diagnosis
DFO should be suspected in any non-healing diabetic foot ulcer overlying bone, particularly when accompanied by persistent local inflammation, visibly exposed bone, a swollen “sausage toe,” or unexplained elevation of inflammatory markers. The 2023 guidelines recommend a stepwise approach that combines several inexpensive tests rather than relying on any single modality.
Bedside and Laboratory Assessment
The probe-to-bone (PTB) test — gentle exploration of the wound with a sterile blunt probe to detect hard, gritty bone — remains a cornerstone of clinical diagnosis. In high-pretest-probability wounds, a positive PTB test combined with an abnormal plain radiograph substantially raises the likelihood of DFO. Among laboratory markers, erythrocyte sedimentation rate (ESR) greater than 70 mm/h has been most consistently associated with osteomyelitis, while C-reactive protein and procalcitonin provide additional diagnostic value when interpreted alongside clinical and imaging findings (Senneville et al., Clinical Infectious Diseases, 2023).
Imaging
Plain radiographs remain the recommended first-line imaging study, with serial films over two to four weeks improving sensitivity for cortical erosion, periosteal reaction, and sequestrum formation. Magnetic resonance imaging (MRI) is reserved for cases in which clinical, laboratory, and radiographic findings remain inconclusive, or when surgical planning requires precise mapping of bone and soft-tissue involvement. While MRI offers high sensitivity, recent comparative data show that accuracy is operator-dependent, and MRI alone may overcall DFO in a meaningful proportion of patients when compared with bone biopsy (Diers et al., Journal of Foot and Ankle Surgery, 2021).
The Role of Bone Biopsy and Microbiology
Bone biopsy with culture and histopathology remains the diagnostic gold standard and is increasingly favoured before initiating prolonged antibiotic therapy. The 2023 guidelines explicitly endorse percutaneous bedside bone biopsy as a safe and accurate procedure when performed through uninfected skin. Bone cultures more reliably identify the true causative pathogens than superficial swab or soft-tissue cultures, which are frequently confounded by surface colonisers. Antibiotic selection guided by bone culture data has been associated with improved cure rates and lower rates of recurrence (Senneville et al., Clinical Infectious Diseases, 2023).
Treatment Strategies
Antibiotic Therapy
Modern management favours narrow-spectrum, culture-directed therapy. The 2023 guidelines support oral antibiotics for clinically stable patients, consistent with broader trial data showing that oral regimens are non-inferior to intravenous therapy for many bone and joint infections. Duration recommendations have shortened markedly: when surgical resection achieves clean (negative) bone margins, only a few days of post-operative antibiotics may be needed; when residual infected bone remains, up to six weeks is suggested. A randomised trial by Gariani and colleagues found that three weeks of antibiotic therapy was non-inferior to six weeks following surgical debridement, and a 2024 systematic review and meta-analysis in Wound Repair and Regeneration found no clear benefit to extending therapy beyond commonly used durations when surgical clearance is adequate.
Surgery and Debridement
Surgical management ranges from conservative bony debridement — resection of infected bone via the wound — to formal osteotomy or partial ray amputation. Residual osteomyelitis after surgery is a strong predictor of poor outcomes; a 2024 systematic review by Reyes and colleagues reported significantly higher rates of treatment failure, recurrence, and reoperation when histologic margins were positive for ongoing infection. Sending the proximal bone margin for histopathology and culture is therefore now considered best practice.
Adjunctive Care
Successful treatment requires more than antibiotics. Concurrent attention to offloading, glycemic control, vascular assessment, and nutritional status is essential. Patients with significant peripheral arterial disease should undergo formal vascular evaluation, since adequate tissue perfusion is necessary for both antibiotic delivery and bone healing.
Key Clinical Takeaways
Diabetic foot osteomyelitis is best diagnosed by combining clinical examination, the probe-to-bone test, plain radiographs, and inflammatory markers, reserving MRI for ambiguous cases and pursuing bone biopsy whenever feasible. Treatment increasingly favours targeted, oral antibiotic regimens of shorter duration, paired with thoughtful surgical debridement and aggressive management of comorbid conditions. Adoption of the 2023 IWGDF/IDSA framework offers a more precise, less toxic, and more limb-preserving approach to a historically difficult problem.
References
- Senneville É, Albalawi Z, van Asten SA, et al. IWGDF/IDSA guidelines on the diagnosis and treatment of diabetes-related foot infections (IWGDF/IDSA 2023). Clinical Infectious Diseases. 2023.
- Schaper NC, van Netten JJ, Apelqvist J, et al. Practical guidelines on the prevention and management of diabetes-related foot disease (IWGDF 2023 update). Diabetes/Metabolism Research and Reviews. 2024;40(3):e3657.
- Gariani K, Pham TT, Kressmann B, et al. Three weeks versus six weeks of antibiotic therapy for diabetic foot osteomyelitis: a prospective, randomized, noninferiority pilot trial. Clinical Infectious Diseases. 2021;73(7):e1539–e1545.
- Reyes E, et al. Residual diabetic foot osteomyelitis after surgery leads to poor clinical outcomes: a systematic review and meta-analysis. Wound Repair and Regeneration. 2024;32(1).
- Pham VP, Tariq R, et al. Clinical guideline highlights for the hospitalist: diagnosis and treatment of diabetes-related foot infections. Journal of Hospital Medicine. 2024.
Comments
