Because terminal bone overgrowth occurs only in transosseous amputations, this type of amputation should be avoided whenever possible. Not surprisingly it is one of the principles of amputation surgery in children. Joint disarticulation is much more preferable to a transosseous amputation. The most obvious example is preference for Boyd or Syme amputation (true ankle disarticulation) over transtibial amputation whenever possible. This is so even in situations where there is an abnormality in the tibia and the temptation on the part of an inexperienced surgeon for a transtibial amputation is high. An example is congenital fibula deficiency (fibular hemimelia) where the tibia can be significantly bowed and misshapen. Another example is a persistent nonunion in the congenital tibial pseudarthrosis where attempts to obtain union have failed and amputation is contemplated. Generally in a skeletally immature individual, amputation should not be performed through the pseudarthrosis or proximal to it. The Syme amputation (ankle disarticulation) is the much preferred procedure. In this situation, the persistent pseudarthrosis can be stabilized with a well-fitting prosthesis and it is not uncommon for union to eventually occur without any further intervention. Similarly, an ischemic insult such as purpura fulminans gangrenous foot can be removed by ankle disarticulation and soft-tissue débridement as needed, then allowing new granulation tissue to proliferate over the extremity and eventually covering it with a skin graft (Figure 3).

In situations when transosseous amputation is inevitable, several strategies can be used to prevent future overgrowth or at least make its treatment less complicated. The two most common reasons for transosseous amputations in children are trauma and malignant tumors. Neither is particularly common in first-world countries. Improved safety features of various machinery, in particular motor vehicles, have decreased the incidence
of severe extremity trauma, and modern limb-sparing tumor surgery likewise has decreased the need for routine extremity ablation in the case of sarcoma of the extremity. The situation is clearly different in developing countries, war-torn areas, and earthquake zones. These conditions can present very different scenarios to the treating surgical team. In the case of trauma, the emergency surgical team may or may not be versed in principles of amputation surgery in children, and the child may have other organ injuries for which treatment can be critical to the child’s survival and by necessity take precedence over an orthopaedic extremity procedure. Dealing with a severe, complex extremity trauma in the middle of the night with less-than-optimal support staff introduces yet another confounding factor. Simple transosseous amputations can be the simplest and fastest procedure to move the child and also the surgical team out of the operating room. However, there can be alternatives. The level of amputation is frequently determined not by osseous injury but by the injury to the soft tissues. In such a situation early débridement of all clearly necrotic tissue, thorough cleansing of any contamination, and planning to have a second look at a 24-to 48-hour interval may allow for a more sophisticated procedure with functional benefit down the road. At the second look, intercalary shortening saving the distal epiphysis and joint surface to optimize soft-tissue coverage or using some parts of the otherwise-to-be-discarded distal part of the extremity to cap the transosseous amputation with a cartilage-covered epiphyseal/metaphyseal transplant or some other length-sparing or joint-saving procedure can be used. In the lower extremity, parts of the tarsal or metatarsal bones or even proximal phalanges can be used. A similar strategy can be used in the case of infection and/or malignancy (Figure 4).