Toe amputation is a common minor vascular procedure and is increasingly performed in the
context of irretrievable diabetic foot infection, with and without concurrent ischaemia.
Approximately 422 million people worldwide have diabetes mellitus and peripheral arterial
disease (PAD) affects approximately 200 million people(1). The intersection between diabetes,
neuro-ischaemic foot ulceration and lower limb amputations is well established(2). Recently
published data from the United States reported overall rates of lower limb amputations in
diabetic patients rose between 2000 and 2015, in part due to a 62% increase in the rate of
minor (foot and toe) amputations(3). It is estimated that 6% of Irish adults are diabetic;
from this, we can extrapolate the burden of managing diabetic foot complications(4). Resource
utilisation notwithstanding, the financial costs of managing diabetic foot complications are
estimated to outstrip some cancers(5). As the prevalence of diabetes mellitus rises amongst
an ageing Irish population, the importance of achieving durable functional outcomes after
partial foot amputation is paramount.
Re-ulceration, re-infection, re-amputation and hospital re-admission after partial foot
amputation for digital gangrene is well documented in the literature in both diabetic and PAD
cohorts(6). Across the literature, rates of re-amputation at five years post-index surgery
for diabetic foot complications range from 45-65% (6, 7). A recent study by Collins et al
reported that, out of 146 Irish patients undergoing minor amputations, 43% (n=63) required
further ipsilateral amputation, 21 (14.4%) of which were trans-tibial or trans-femoral(8).
Chronic kidney disease, diabetes with or without poor gylcaemic control, peripheral
neuropathy, peripheral arterial disease, ongoing tobacco smoking, obesity (BMI >30),
concurrent sepsis at the time of index operation have all been identified as independent risk
factors for amputation failure and the need for revision(9-11). While numerous studies have
investigated patient-dependent factors predictive of amputation failure, there is a dearth of
evidence examining the impact of surgical technique on this commonly performed procedure.
An exhaustive search of the literature surrounding surgical technique and outcomes after ray
amputation yielded several papers on the benefits of various soft tissue flaps for covering
wound defects but just one detailing a particular methods of bone transection. However,
Moodley et al focused on the use of a Gigli saw, which is beyond the scope of this
feasibility study(12). There have been no randomised controlled trials evaluating the impact
of metatarsal transection method on outcomes after ray amputation, specifically whether a
manual bone cutter or an electric/oscillating/pneumatic bone saw were used. We hypothesise
that utilising a manual bone cutter is more subject to inter-user variability, as it depends
on the physical strength of the operating surgeon; improperly applied forces are liable to
fracture the remaining bone, leaving small comminuted fragments that may become necrotic and
act as a nidus for further infection within the wound bed. Furthermore, using an oscillating
microsaw has the advantage of providing a clean bony transection regardless of the physical
strength of the operator, however it may cause more damage to the surrounding connective
tissues and disturb microvascular periosteal supply, which could also lead to osteonecrosis.
We propose a pilot randomised controlled trial to test the feasibility and to generate
sufficient data to permit sample size calculation for a trial designed to evaluate the
outcomes after ray amputation using either a bone cutter or a bone saw.