Open or closed minor amputation for diabetic gangrene?

Background: Amputation below the ankle at the diabetic foot is rarely successful, if carried out as closed amputation (with primary wound closure).

Objective: To assess the outcome of open and closed (minor) amputations in diabetic patients from three hospitals. Patient charts including pathohistology reports were evaluated.

Methods: A total of 80 diabetic patients were considered, of whom 47 had critical foot ischaemia (CFI) Fontaine stage IV, 5 had endstage renal failure with haemodialysis treatment, and 72 had polyneuropathy.

Results: During 96 procedures, 60 toes and 48 metatarsal bones were amputated. A closed amputation (CA, n=54), or an open amputation (OA, n=42) had been performed, at the discretion of the surgeons. Toes rather than metatarsal bones were amputated more often with CA than with OA (p=0.0018). Following CA, 14 wounds (26%) healed by primary intention, whereas 40 wound did not; in 15 cases (28%), reamputations were required. Following OA, 26 wounds (62%) healed by secondary intention, and 14 cases (33%) required reamputation. Histopathology revealed osteomyelitis at the osteotomy site in 34 cases (64%) of CA, versus 31 cases (78%) of OA. Following CA, 77% of 9 cases without CFI, and with healthy bone at the osteotomy site healed by primary intention, versus 4% of 25 cases with CFI and osteomyelitis at the osteotomy site (p<0.0001).

Conclusions: Closed amputation was successful only in absence of CFI and of osteomyelitis at the osteotomy site. The extension of osteomyelitis was grossly underestimated. Preoperative MR imaging (rather than X-ray) to diagnose osteomyelitis could improve the outcome of a closed minor amputation, and justify its preferred application at the diabetic foot.