Comment on van Netten, et al: Definitions and criteria for diabetic foot disease

Summary Objective The International Working Group on the Diabetic Foot (IWGDF) recently published updated definitions for the diabetic foot field. However, the suggested definitions of lower limb amputations differ from the definitions of the International Organization of Standardization (ISO), which may create problems when implementing the definitions. This paper compares and discusses the amputation definitions of IWGDF and ISO. Results Despite many similarities, the IWGDF and ISO systems have some important differences. First, the IWGDF uses the term “minor amputation” which is value‐laden, arbitrary and has been defined in several different ways in the literature. Second, the IWGDF system lacks descriptions of amputations distal or through the ankle, which may increase the risk for misclassification. Third, hip disarticulations and transpelvic amputations are not included in the IWGDF system. Conclusion It is suggested that future updates of the IWGDF definitions should be aligned with those of ISO, to meet the goal of global consensus on terminology related to lower limb amputation.

Results: Despite many similarities, the IWGDF and ISO systems have some important differences. First, the IWGDF uses the term "minor amputation" which is value-laden, arbitrary and has been defined in several different ways in the literature. Second, the IWGDF system lacks descriptions of amputations distal or through the ankle, which may increase the risk for misclassification. Third, hip disarticulations and transpelvic amputations are not included in the IWGDF system.

Conclusion:
It is suggested that future updates of the IWGDF definitions should be aligned with those of ISO, to meet the goal of global consensus on terminology related to lower limb amputation.

K E Y W O R D S
amputation, classification, diabetic foot bone or through a joint', and ISO defining it as 'surgical removal of the whole or part of a limb'. Additionally, most lower limb amputation levels can be found in both classification systems (Table 1).
Despite these similarities, there are some important differences.
First, the IWGDF categorizes amputations into two groups: major amputations and minor amputations. This traditional dichotomization has received critique over the years, among other things, for being value-laden: a minor amputation may not be experienced as minor by the patient. Also, the distinction between major and minor amputations is somewhat arbitrary as certain levels of partial foot amputations (minor amputations) can have similar effects as a transtibial amputation (major amputation) on gait characteristics, energy expenditure and quality of life. 3 Furthermore, minor amputations are defined differently in the literature, for example as amputations distal to the tarsometatarsal joint, 4 distal or through the tarsometatarsal joint, 5 distal to the ankle, 6 or distal or through the ankle. 1 This previous point is particularly problematic for comparison and communication, as the result is two groups (major/minor) which cannot be guaranteed as mutually exclusive. Second, the IWGDF system lacks descriptions of amputations distal or through the ankle (Table 1), which may increase the risk for misclassification. For example, surgical removal of a whole digit may be misclassified as a toe amputation, when the correct classification is metatarsal-phalangeal disarticulation. Third, hip disarticulations and transpelvic amputations are not included in the IWGDF system. This may be due to the fact that amputations at these levels are uncommon and, in most cases, not related to diabetes. 7-10 Regardless, it could be seen as counterproductive to use one system to categorize amputations related to diabetes, and another system to categorize other amputations. One may object that the ISO system also lacks amputation levels, as the IWGDF differentiates between proximal and distal transmetatarsal amputations, which the ISO does not.   11 We agree and would welcome a similar approach in future updates of the IWGDF definitions, suggesting that the definitions of amputations be aligned with those from ISO. By doing so, we can ensure that the goals of these classification systems (to facilitate communication and comparison) are in alignment and that both systems are of maximum benefit to those working in the multiple fields that make use of these systems.

ACK N OWLED G EM ENTS
Not applicable.

GJ is a consultant for Novo Nordisk and AJ is an employee of Össur
Clinics Scandinavia. DFR has no conflicts of interest to disclose.

AUTH O R S CO NTR I B UTI O N S
GJ wrote the first draft. All authors have contributed to writing, discussions of the content, and have read and approved the final manuscript.

E TH I C S S TATEM ENT
Not applicable.

DATA AVA I L A B I L I T Y S TAT E M E N T
Not applicable.