Similarity in functional outcomes with partial foot and transtibial amputation focuses attention on complication rates

Partial foot amputation is increasingly common in Australia,1 and the rates of complications are disproportionately high compared with people who have transtibial (below-knee) amputation.2We draw attention to these recent observations in our publications, highlighting that contemporary beliefs about partial foot amputations do not always result in optimal outcomes, especially for older people.1,3

A lower limb amputation is performed in Australia nearly every hour. Of the 8000 lower limb amputations in Australia each year,1 many are the end result of the long-term complications of diabetes such as peripheral vascular disease, neuropathy and chronic non-healing ulceration of the foot.

There has been a considerable shift in the types of lower limb amputations performed in Australia over the past decade.1 The incidence of transfemoral and transtibial amputation has declined and the incidence of partial foot amputation has increased.1 In Australia three-quarters of all lower limb amputations are now at the partial foot level.1

The shift to more distal amputation could be seen by some as a positive outcome. However, partial foot amputation can be associated with disproportionately high rates of complications and revision surgery. Between 30% and 50% of people with partial foot amputation experience complications such as dehiscence, ulceration or wound failure.4,5 However, these sorts of wound complications seem to affect just 10%–20% of people with transtibial amputation.6–8 Only around half of all partial foot amputations heal adequately.4,7 Efforts to achieve wound healing after partial foot amputation often occur over many months and cost between $27 000 and $36 000 depending on the treatment approach used.9 In comparison with the low rates of healing in partial foot amputation, around 80% of transtibial amputations heal.10,11 Subsequent amputation on the same limb is necessary in about one-third of people with an initial partial foot amputation; more than double that observed in people with an initial transtibial amputation.2,4

The high risk of complications and secondary amputation are sometimes considered reasonable when weighed against the functional benefits of partial foot amputation.12,13 Implicit in this reasoning is the belief that, if successful, partial foot amputation will lead to improved outcomes compared with transtibial amputation.

Emerging research suggests that many functional outcomes are similar in people with partial foot and transtibial amputation. For example, once the metatarsal heads are removed, people with partial foot and transtibial amputations have a strikingly similar gait pattern: power generation at the ankle is negligible and the hip joints provide the compensatory work required to walk.3 Similarly, walking speed and energy expenditure are also much the same.3 In terms of quality of life, only descriptive data are available. While these data suggest that quality of life is similar in both groups,3 we do not know whether the purported benefits of partial foot amputation, like walking short distances without a prosthesis,5 are important from the patient’s perspective. The lower mortality associated with partial foot amputation may have nothing to do with the amputation procedure per se.14 It is likely that people considered suitable candidates for partial foot amputation live longer because they have less advanced vascular disease than those requiring a transtibial amputation.

Considering that the functional outcomes for people with partial foot and transtibial amputation are similar, it is difficult to understand why the high risk of complications and secondary amputation associated with partial foot amputation do not weigh more heavily in decisions about amputation surgery. Arguably, minimising complications and repeat surgeries should be the primary goal given that most people are in the last years of their life, are often chronically unwell and have limited mobility.

When viewed from the patient’s perspective, it is perhaps easier to understand: individuals faced with the difficult reality of lower limb amputation often choose the procedure that preserves as much of their foot as possible. Yet when informing these decisions, clinicians have an obligation to provide information consistent with the emerging evidence, which suggests that people with partial foot amputation have very similar functional outcomes compared with those with transtibial amputation, yet markedly greater risks of complications and secondary amputation on the same limb.3

With a better understanding of the research data, we contend that more people might initially choose a more invasive procedure to minimise the risk of complications and further amputation surgery in the future.

If further research supports our interpretation of the emerging evidence,1,3 there will be a strong case for choosing between partial foot and transtibial amputation based on the likelihood of healing rather than perceived functional benefits. With this approach, more first amputations are more likely to be final ones.