The goals of management for children with a limb deficiency are limb preservation and length equalization. A guiding principle is to maintain or create a biologic knee, as the energy consumption with a mechanical knee is so much greater than normal.

A variety of strategies are employed, some of which may include amputation. If an amputation is part of the management strategy for a patient with a biologic knee, the etiology greatly influences the specific type of amputation performed. An amputation that preserves the heel pad (ankle disarticulation or Boyd amputation) is the preferred choice and is generally an elective procedure. In contrast, transtibial amputation is usually a salvage procedure performed if it is not possible or not practical to preserve the heel pad as a result of trauma, infection, or nonunion. Jeans et al. investigated how these two amputee populations compare with respect to function and walking.

The quantitative (three-dimensional motion analysis) and functional (Pediatric Outcomes Data Collection Instrument [PODCI]) assessment tools used in their study are consistent with what most clinicians have observed for years: patients with a below-the-knee amputation walk virtually normally, regardless of the amputation type or residual tibial length. Although some statistically significant differences between the groups were noted, they were clinically unimportant or easily explained by the inherent bias resulting from segregation of the population by diagnosis (i.e., the heel pad preservation group was dominated by patients with a diagnosis of fibular hemimelia with its associated external femoral rotation). In fact, one reason that these differences were statistically significant is that the number of subjects was quite large, which is both a strength and a weakness of the study. One must not overinterpret significant differences that are small in magnitude when the sample size is large.

The secondary question alluded to in this study, the issue of the appropriate amputation type and level, is actually a more important one, as the clinician cannot objectively recommend which type of foot would be the “right” choice for an individual merely on the basis of clinical observation. Three categories of prosthetic feet (defined on the basis of their mechanical characteristics) are described, and their costs increase incrementally with increasing complexity. As the difference in tibial length must exceed a certain minimum value to permit fitting some of the more advanced prostheses, the authors attempt to address whether selection of such a prosthesis actually yields a superior outcome. However, data were not reported separately for patients whose residual tibial length made them eligible for a medium or high-performance prosthesis and those who were not eligible because their residual tibial length was too great. If the latter group is small, this secondary question cannot be assessed with the study population. In addition, if subsequent interventions (e.g., the eight epiphysiodesis procedures that were performed) are able to achieve a universally “fittable” limb, then the appropriate amputation becomes even less of an issue.