Background: There is a disconcerting rate of bilateral limb loss in patients with diabetes. Therefore, this study aimed to explore plantar loading of the surviving foot following unilateral trans-tibial amputation within a wider context of daily walking activity to investigate the precise risk to the surviving limb.
Methods: Twenty-one subjects with diabetic neuropathy and trans-tibial amputation were matched for weight; height; age and gender with 21 control subjects with diabetic neuropathy without history of plantar ulceration. Gait parameters, in-shoe plantar pressure distribution and daily walking (using the step activity monitor) were recorded. Student's t-tests were used to compare groups (alpha-level: 0.05).
Findings: The trans-tibial amputations group walked almost 30% slower compared to controls (P < 0.01), with reduced cadence (P < 0.01), and shorter strides (P < 0.01). Despite walking slower, the surviving foot showed higher mean peak plantar pressures in the trans-tibial amputations group over the heel (P < 0.001) however there was no significant difference over the I-II and lateral III-IV-V metatarso-phalangeal regions. Pressure time integral was higher over the heel (P < 0.00), I-II (P < 0.01) and III-IV-V metatarso-phalangeal (P < 0.05) in the trans-tibial amputations group. The amputee group walked less steps per day (P < 0.01).
Interpretation: Adaptations in gait and level of walking activity affect plantar pressure distribution and ultimately the risk of ulceration to the surviving foot. Therefore rehabilitation measures should consider implications for plantar loading and the potential risk of ulceration to the surviving foot.