Clinical-Pathological Characterization of Diabetic Foot Infections: Grading the Severity of Osteomyelitis

The present study has 3 aims: (a) to characterize the clinical and pathological features of diabetic foot infections, (b) to show the range of clinical presentations of moderate infections, and (c) to analyze the different behavior of diabetic foot osteomyelitis regarding to its clinical presentation. A definitive diagnosis of the type of infection was made based on intraoperative findings and histopathology. Diabetic foot infections were classified into 2 types: soft tissue and bone infections. Mild infections were always superficial. Severe infections included 75% of necrotizing soft tissue infections. Moderate infections showed ample range of clinical presentations. Eighty-one patients presented osteomyelitis. Osteomyelitis was further classified as follows: osteomyelitis without ischemia and without soft tissue involvement (class 1), osteomyelitis with ischemia without soft tissue involvement (class 2), osteomyelitis with soft tissue involvement (class 3), and osteomyelitis with ischemia and soft tissue involvement (class 4). Forty-eight patients (59.3%) with osteomyelitis underwent conservative surgery, 32 (39.5%) had minor amputations including 9 open transmetatarsal amputations, and there was 1 (1.2%) major amputation. The characterization of osteomyelitis into 4 classes showed a statistically significant trend toward increased severity and increased amputation rate and mortality. In conclusion, the clinical presentation of foot infections in diabetic patients is very heterogeneous and can be classified into soft tissue infections (cellulitis, superficial and deep abscesses, and necrotizing soft tissue infections) and osteomyelitis, which was the most frequent type of infection found in the author's series. Their division into 4 classes showed a statistically significant trend toward increased severity, amputation rate, and mortality. The diagnosis of deep soft tissue infections associated with osteomyelitis may be difficult to achieve before surgery.