Uncertainty in diabetes amputations

ADVICE to patients about whether a partial foot or transtibial (below-knee) amputation is the best treatment for long-term complications from diabetes remains clouded following the publication of an opinion article in the MJA.

Dr Michael Dillon, senior lecturer in prosthetics and orthotics at La Trobe University in Melbourne, and coauthors wrote that of the 8000 lower limb amputations performed in Australia each year, many were the end result of long-term complications from diabetes such as peripheral vascular disease, neuropathy and chronic non-healing ulceration of the foot. (1)

However, the authors said partial foot amputations (PFAs) did not always result in optimal outcomes, particularly in older patients, with rates of complications following PFAs “disproportionately high” compared with below-knee amputations.

The authors reported that 30%–50% of PFA patients experienced complications such as ulceration or wound failure, compared with 10%–30% of those who had transtibial amputations.

They said about half of all PFAs healed adequately compared with about 80% of transtibial amputations.

The authors called for more research, saying that if it supported their interpretation of the emerging evidence more people might initially choose the more invasive procedure of transtibial amputation to minimise the risk of complication and the need for further amputation surgery in the future.

Dr John Quinn, director of vascular surgery at Princess Alexandra Hospital in Brisbane and president of the Australasian and New Zealand Society of Vascular Surgeons, told MJA InSight that technological advances in the past 4–5 years had changed the outlook for PFA patients “quite dramatically”.

Dr Quinn said there had been major technological advances in revascularisation of the lower limbs in recent years, including some that were rarely available in 2010.

“But they are very much so in 2014. It’s completely different now — we do more digital amputations and major limb amputations are down”, he told MJA InSight.

“Things have changed quite dramatically, with new techniques and technology. We now have the ability to open occluded vessels all the way down. We’re getting people out of hospital faster, the patients’ ulcers are healing, their pain is gone, they’ve got both legs and maybe nine toes.”

Dr Salih Salih, a consultant geriatrician at Princess Alexandra Hospital in Brisbane, said the issue was not as simple as deciding where to amputate.

“This is a much more complex decision than that”, he told MJA InSight. “Most of these patients have several comorbidities, including cardiac disease, they are older, more frail and are therefore not good candidates for prostheses. It is hard to make a blanket decision about what kind of surgery they should have.”

Dr Salih said some patients refused amputation. However, if amputation was considered, it was “true to say” the higher the amputation, the better the blood supply and the healing.

Mr Peter Lazzarini, a senior research fellow in the foot disease research program at Queensland University of Technology’s School of Clinical Sciences, told MJA InSight that he found the opinion article “challenging”.

He said he would find it worrying if GPs read the MJA article and recommended their diabetic foot patients consider a major amputation on the strength of it.

“[The authors] have a point about re-amputations — there is a longer healing time with mid foot amputations but with major amputation there is an increased risk of amputation of the other leg and an increased risk of dying earlier”, Mr Lazzarini said.

“When you look at [the evidence about] function it is at least trending better for mid foot amputations in terms of speed, power, the number of steps, fatigue doing the same activities. And quality of life is better than for transtibial amputations.”

Mr Lazzarini cited a recent small controlled trial from Spain, published in Diabetes Care, which found that using antibiotics alone for 90 days was not inferior to conservative surgery (removing infected bone without amputating any part of the foot) in the treatment of diabetes foot osteomyelitis. (2)

An accompanying editorial said recently published guidelines on managing diabetic foot infections from the International Working Group on the Diabetic Foot and the Infectious Diseases Society of America “illustrate the current state of uncertainty”. (3), (4), (5)

“Among the remaining issues to address in treating diabetic foot osteomyelitis are better defining the subgroup of patients for whom surgery may be unnecessary and determining the optimal duration and route of antibiotic therapy”, the author wrote.

 “We need a lot more research in this area”, Mr Lazzarini told MJA InSight.

1. MJA 2014; 200: 252-253
2. Diabetes Care 2014; 37: 789-795
3. Diabetes Care 2014; 37: 593-595
4. Specific guidelines for the treatment of diabetic foot infections 2011
5. Practice guideline for the diagnosis and treatment of diabetic foot infections 2012