Plantar pressures are higher in diabetic patients following partial foot amputation

The purpose of this study was to compare peak plantar pressure in diabetic patients with and without foot-level amputation. This project was conducted as a case-control study. We enrolled 27 cases and 150 controls diagnosed with diabetes mellitus. Cases were defined as patients with a history of forefoot-level amputation (digit or ray amputations distal to the tarsometatarsal joint) secondary to an infected forefoot wound. Controls were defined as subjects that had never had a foot ulceration. We used a pressure platform system to evaluate dynamic barefoot pressure on the sole of the foot. There was no significant difference in vascular perfusion or body mass index between the case and control groups. Patients with a foot-level amputation were nearly ten times more likely to present with limited joint mobility or a rigid foot deformity than those without amputation (92.6% vs. 44.0%, p < 0.0001, X2 = 13.0, Odds Ratio = 9.8 CI = 2.2 to 43.0). Peak plantar pressure was significantly higher for patients with amputations compared to controls (80.0 +/- 31.1 N/cm2, vs, 62.5 +/- 21.0 N/cm2, p < 0.001). Peak pressure and limited joint mobility have long been associated with ulceration. We conclude that increased pressure and contractures associated with biomechanical compensation following a partial foot amputation further increase plantar pressure, placing an already high-risk limb at further risk for tissue breakdown and reamputation.