Prognostic difference between soft tissue abscess and osteomyelitis of the foot in patients with diabetes: data from a consecutive series of 452 hospitalized patients.

From January 2008 to December 2010, 452 patients with diabetes were admitted to our diabetic foot unit because of deep soft tissue abscess (group A: n = 210) or chronic osteomyelitis (group B: n = 242). Patients from group A underwent emergency debridement in the operating room. Patients from group B underwent elective surgery. Twenty-six (5.8%) major amputations were performed: of these, 18 (8.57%) were performed in patients from group A and 8 (3.31%) were performed in patients from group B (p = .024). Multivariate analysis showed the independent role on amputation outcome of the abscess (odds ratio, 2.64; p = .029; confidence interval [CI] 1.11 to 6.28), dialysis treatment (odds ratio, 3.17; p = .039, CI 1.06-9.51), and C-reactive protein > 0.5 mg/dL (odds ratio, 3.75; p = .022, CI 1.21-11.64). In group A, 43 (22.6%) patients healed only with drainage, and 147 (70.0%) minor amputations were performed: 53 (36.1%) at the level of the forefoot and 94 (63.9%) at the level of the midfoot. In group B, 234 (96.7%) minor amputations were performed, 208 (88.9%) at the forefoot and 26 (11.1%) at the midfoot level (p < .001). Fourteen postoperative complications occurred in patients from group A and 2 in patients from group B (p < .001). In group A, 3 patients died during hospitalization, 1 from septic shock and 2 from sudden death. None of the group B patients died. This study demonstrates that the severity of a foot soft tissue abscess is not comparable with that of a chronic osteomyelitis not only because of a higher rate of major amputation, but also because of a much more proximal level of minor amputation.