Evaluation of routine proximal bone analysis for microbiology and histopathology in diabetes-related foot infections and osteomyelitis.

PURPOSE: The value of proximal bone analysis for surgical clearance of infection remains debated. Real-world practice traditionally utilized proximal bone microbiology rather than histopathology to diagnose residual diabetes-related osteomyelitis of the foot (DFO) post-amputation. We assessed the concordance between proximal bone microbiology and histopathology in determining residual infection and their predictability for revision operation in DFO and diabetes-related foot infection (DFI).

METHODOLOGY: A single-centre retrospective study was conducted between June and December 2020 at a tertiary institution. We recruited patients with diabetes mellitus who had minor amputations for DFO and DFI and analyzed their proximal bone microbiology, histopathology and outcomes at 6 months.

RESULTS

Eighty-four patients were recruited; 64 (76.2%) were male. The mean age was 69.3 years. The mean HbA1c was 8.6%. Seventy-seven operations were performed for DFO and 17 for DFI. Negative microbiology showed complete concordance with histopathology; and none had revision operation (P = 0.99). Positive microbiology had 9.8% concordance with histopathology (P = 0.99). Positive histopathology was associated with a higher rate of revision operation (80% vs. 12.5%; P = 0.01). High preoperative C-reactive protein was associated with residual DFO (P = 0.02) and revision operation (P = 0.01).

CONCLUSION

Positive histopathology was more reliable for determining significant residual DFO and predicting revision operation. Positive microbiology was valuable for guiding antibiotic selection. We suggest routine proximal bone analysis for both histopathology and microbiology to optimize the treatment of DFO and DFI.