Bone infection—known as osteomyelitis—is one of the most serious and difficult-to-treat complications of diabetic foot disease. It affects an estimated 20% of patients presenting with diabetic foot infections in outpatient settings, and up to 60% of those hospitalized with severe infections. Left unrecognized or inadequately managed, diabetic foot osteomyelitis (DFO) is a leading driver of lower-extremity amputation. This post reviews the current evidence on how DFO is recognized, imaged, and treated, drawing on the most recent peer-reviewed guidelines and clinical research.
Understanding Diabetic Foot Osteomyelitis
DFO typically develops when bacteria from an overlying soft-tissue wound invade adjacent bone. In people with diabetes, this process is facilitated by peripheral neuropathy (which blunts pain sensation and allows wounds to go unnoticed), peripheral arterial disease (which impairs blood delivery and immune response), and chronic hyperglycemia (which broadly impairs immunity and wound healing). The bones most commonly involved are the metatarsal heads and phalanges of the forefoot, though midfoot and hindfoot osteomyelitis also occur—particularly in the context of Charcot neuroarthropathy.
A 2024 systematic review and meta-analysis in Frontiers in Clinical Diabetes and Healthcare confirmed that Staphylococcus aureus remains the predominant pathogen in DFO, though polymicrobial infections involving Gram-negative organisms and anaerobes are common in chronic or post-surgical wounds. Methicillin-resistant S. aureus (MRSA) is increasingly prevalent, particularly in patients with prior antibiotic exposure.
Clinical and Laboratory Diagnosis
No single clinical test reliably confirms or excludes DFO, so diagnosis relies on an integrated assessment combining bedside examination, laboratory biomarkers, and imaging. The 2023 IWGDF/IDSA guidelines—the most comprehensive and widely adopted international framework for diabetic foot infections—recommend the following stepwise approach.
The probe-to-bone (PTB) test is a simple, low-cost bedside manoeuvre in which a sterile metal probe is passed through an open wound toward underlying bone. A 2026 study in the Journal of Clinical Medicine comparing diagnostic tools found the PTB test has high sensitivity (0.87) and specificity (0.91), along with a strong negative predictive value of 0.98—making it particularly useful for ruling out bone involvement when negative.
Serum inflammatory biomarkers—including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and procalcitonin (PCT)—are routinely used to support the diagnosis. A 2024 meta-analysis by Ansert et al. in Wound Repair and Regeneration found that while ESR, CRP, and PCT each show moderate individual performance (sensitivities and specificities ranging from 0.72 to 0.77), PCT demonstrated the best overall accuracy for distinguishing DFO from soft-tissue-only infection. The 2023 IWGDF guidelines recommend using these biomarkers in combination with clinical findings rather than in isolation.
The Role of Imaging
Plain radiography remains the first-line imaging study and may reveal periosteal reaction, cortical erosion, or lytic lesions—but these findings typically lag behind the actual onset of infection by two to four weeks. When plain X-ray and clinical findings are diagnostic, the 2023 IWGDF guidelines state that no further imaging is required.
When the diagnosis remains uncertain, MRI is the preferred advanced imaging modality. A large 2020 systematic review and meta-analysis in the European Journal of Radiology (Dinh et al.) pooled data from 23 studies and found MRI to have a sensitivity of 96.4% and specificity of 83.8% for DFO—the highest diagnostic accuracy among available imaging tests. MRI also delineates the extent of bone involvement and identifies adjacent soft-tissue infection, abscess, or sinus tracts, all of which inform surgical planning.
For patients in whom MRI is contraindicated (e.g., those with certain implanted devices), 18F-FDG PET/CT and radiolabelled leukocyte scintigraphy are recognized alternatives in the 2023 guidelines. The 2025 ACR Appropriateness Criteria update for suspected foot osteomyelitis in diabetic patients similarly endorses MRI as the imaging study of choice, with PET/CT reserved for specific clinical scenarios.
Medical Versus Surgical Treatment
Historically, surgical resection of infected bone was considered the definitive treatment for DFO. A 2021 systematic review in the Journal of Clinical Medicine (Lesens et al.) examined 33 studies—including 6 randomized controlled trials—and found that medical-only management with antibiotics achieves remission rates comparable to surgical treatment in selected patients with forefoot osteomyelitis, no peripheral arterial disease, and no exposed bone or necrotic tissue. The 2023 IWGDF guidelines now explicitly recommend that antibiotic therapy without surgical resection may be considered for uncomplicated forefoot osteomyelitis, particularly in patients who are high surgical risk or who wish to avoid amputation.
That said, surgical debridement or limited bone resection remains appropriate—and often preferable—when there is accompanying abscess, extensive necrosis, failure of initial antibiotic therapy within two to four weeks, or loss of structural foot integrity. The goal in all cases is limb preservation wherever feasible.
Antibiotic Therapy and Duration
Antibiotic selection should ideally be guided by culture results from bone biopsy, which the 2023 IWGDF guidelines identify as the diagnostic gold standard. Empirical regimens typically cover Gram-positive organisms including MRSA when risk factors are present, and are broadened to cover Gram-negatives and anaerobes in chronic or previously treated wounds.
A key clinical question has been optimal treatment duration. A 2021 prospective randomized pilot trial (Tone et al., published in Open Forum Infectious Diseases) found that three weeks of antibiotic therapy was non-inferior to six weeks following surgical debridement of DFO. Building on this evidence, the 2023 IWGDF guidelines recommend up to three weeks of antibiotics after minor amputation when bone-margin cultures are positive, and approximately six weeks for DFO managed without any surgical bone resection. This represents a significant shift toward antibiotic stewardship—limiting prolonged courses that carry risks of toxicity, resistance, and Clostridioides difficile infection.
Key Takeaways
Diabetic foot osteomyelitis remains a clinically challenging diagnosis that requires a systematic, multimodal approach. The probe-to-bone test and serum biomarkers provide initial bedside guidance, with MRI offering the highest diagnostic accuracy when the diagnosis is uncertain. Treatment should be individualized: medical management with antibiotics is a valid strategy for uncomplicated forefoot osteomyelitis in carefully selected patients, while surgery remains important for complex cases. Shorter antibiotic courses—guided by bone culture results—are now supported by evidence and endorsed by international guidelines, reflecting a more targeted approach to infection management in this high-risk population.
References
- Senneville E, et al. IWGDF/IDSA guidelines on the diagnosis and treatment of diabetes-related foot infections. Clinical Infectious Diseases. 2023. doi:10.1093/cid/ciad527
- Dinh MT, et al. Imaging for detection of osteomyelitis in people with diabetic foot ulcers: a systematic review and meta-analysis. European Journal of Radiology. 2020;131:109215.
- Lesens O, et al. Medical versus surgical treatment for the management of diabetic foot osteomyelitis: a systematic review. Journal of Clinical Medicine. 2021;10(6):1237.
- Ansert E, et al. Update of biomarkers to diagnose diabetic foot osteomyelitis: a meta-analysis and systematic review. Wound Repair and Regeneration. 2024. doi:10.1111/wrr.13174
- Tone A, et al. Three weeks versus six weeks of antibiotic therapy for diabetic foot osteomyelitis: a prospective, randomized, noninferiority pilot trial. Open Forum Infectious Diseases. 2021;8(1):ofaa536.
- ACR Appropriateness Criteria: Suspected Osteomyelitis of the Foot in Patients with Diabetes Mellitus — 2025 Update. Journal of the American College of Radiology. 2025.
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