Injuries in children that are severe enough to result in a major lower extremity amputation are not common. Cumulatively, many of these patients exist despite major advances in limb salvage, revascularization procedures, and limb replantation. Complications are particularly common in the pediatric patient with a traumatic amputation and need to be anticipated early. Not only are the typical complications of infection, delayed healing, compartment syndromes, and chronic pain issues present but also bony overgrowth, progressive angular deformity with or without physeal damage, and poor residual limb durability into adult life. It is of fundamental importance that the surgical team recognize an injury that ultimately is best managed by a level of amputation. If an amputation decision is made, the team then must finally try to create a residual limb that is durable and supports the high level of activity in these young individuals.

First, information on overall etiology and incidence data relevant to the pediatric lower extremity trauma amputee is provided. Next, current decisionplanning strategies regarding reconstruction versus amputation in pediatric patients affected by major lower extremity traumas are discussed. Specific levels are then addressed, including ankle-level amputation, transtibial amputation, knee disarticulation, and above-knee amputation. Each level includes specific complicating issues, key aspects of surgical techniques, and current prosthetic strategies. Partial foot amputations, which represent a high percentage of pediatric lower extremity amputations, are outside the scope of this chapter. Before final conclusions, psychological and medical legal issues should be discussed.

The exact incidence of major (anklelevel and above) pediatric lower extremity traumatic amputations is not known. Most traumatic amputations occurring in the United States in children and adolescents involve fingers and toes. In a study of emergency department visits from 1990 to 2002, with an amputation diagnosis in children, 91% of these were to fingers.¹ Borne et al² studied data in children from 2002 to 2011 using the National Trauma Data Bank, noting 54% finger and 20% toe amputations. Major lower extremity amputations in this study showed 5.9% foot and ankle, and 14.8% transtibial amputations and transfemoral amputations of the 2,238 amputations identified. Conner,³ using the Kids Inpatient Database, also noted that of 956 pediatric traumatic amputations in 1 year (2003) severe enough to require hospitalization, 64% were to fingers and toes, with foot and leg combined at 10%. The Borne study indicates that a per-year incidence of ankle-level and above traumatic amputations would average approximately 93 per year, a number nearly identical in the Conner review.^2,3 National Trauma Data Bank data, however, are not all inclusive because they do not have specific data from private or nontrauma centers. Inclusion of data is highly encouraged from trauma centers but not mandated. A significant additional factor is that in studies on young adults, lower extremity traumatic injuries that ultimately result in amputation are amputated months to years after initial hospitalization and are not part of initial database searches.⁴

The etiology and mechanism of primary injury that results in a lower extremity amputation in children varies with age and which region of the world or portion of the United States the patient lives. In the study by Loder et al⁵ of 165 pediatric traumatic amputees treated in the upper Midwest over a 20-year period, the most common mechanism was powered lawn mower (PLM) trauma (69 of 165) followed by farm machinery (57 of 165) and then motor vehicle collision (38 of 165). The Borne et al² study of the entire United States
further reflected PLM as the primary mechanism of major lower extremity amputation in young children (age 5 years or younger), but motor vehicle collision was most common in children older than 12 years. This study also indicated farm machinery was the second most common overall mechanism, which caused mostly finger and toe amputations (83%). Intentional and unintentional firearms trauma accounted for 6.1% of all pediatric amputations with 80% in the adolescent age bracket. Firearms trauma in 16-to 17-year-olds resulted in high levels of major lower extremity amputation (48% transfemoral amputations and transtibial amputations) with identified vascular injury from firearms in 64% of transtibial amputations and 75% of transfemoral amputations. Siracuse et al⁶ noted higher risk of amputation in firearm trauma compared with nonfirearm penetrating trauma. Other causes of major lower extremity amputations in children include train injuries, thermal injury, and explosion.^2,3,5

PLM trauma in the United States remains a significant cause of major lower extremity amputation, notably backover trauma in young children. Children with small body size can be hard to see and operators using hearing protection are unable to sense them when in proximity (Figure 1). A six times higher likelihood of severe lower extremity amputation in children younger than 5 years has been noted when comparing with those aged 6 years and older.² In the 25-year study by Ren et al⁷ of PLM injuries in children, an estimated 1,641 backover injuries occurred, 70% in children younger than 5 years. This study also noted a significant decrease in PLM injuries from 1990 to 2014. The decrease in PLM-related injury may be due to increased public awareness in addition to improved safety features. Multiple studies have shown that in evaluating the rate of PLM trauma versus age, a bimodal pattern is clearly present with a peak in ages 1 to 5 years and a second peak in ages 10 to 17 years.^2,3,6,8 Younger children are generally struck by PLMs; older children are usually injured when operating PLMs. Males were predominant in all age groups, with higher percentages of males in older age groups.^2,3 Quantification of exact PLM types involved in injury is needed. This is particularly true of zero radius mowers that require backup to fully operate steering. Currently, safety features on non-zero radius mowers include no mow in reverse and have been present on most equipment since 2004 (American National Standards Institute/Outdoor Power Equipment Institute B71.1-2003). Safety features can be bypassed either by override switches provided by the manufacturer or by nonauthorized fixes often presented on social media video.

Worldwide, etiologies that cause major traumatic lower extremity amputations in children are different. Ahmad et al⁹ reported a series of traumatic amputations primarily involving the lower extremities in children and adolescents from northern India. These authors indicated road trauma followed by train accidents as the most common mechanisms. Roche and Selvarajah¹⁰ retrospectively reviewed 83 major pediatric lower extremity amputations in the United Kingdom, noting accidents on the road accounting for 63%, nearly a third being pedestrians struck by a bus. Train and farm trauma followed with surprisingly no PLM listed as a mechanism.

Landmine explosion trauma continues to be a significant etiology and unfortunately involves a high percentage of children and adolescents.¹¹ Soroush et al¹² studied 3,713 landmine victims from Iran during the period 1988 to 2003. These authors identified 1,499 amputations with 41% in patients age 18 years or younger; most of the amputations being transtibial. The primary reason for encountering a landmine was walking with livestock for grazing. The actual number of worldwide traumatic amputations involving children from landmines is unknown. It is established that landmine blast injuries are fatal in 21.1% of these pediatric patients because of their small body mass and proximity of organ systems to the blast, compared with 10.7% in adults.¹³

A key factor in managing severe pediatric lower extremity trauma is the surgical team’s initial strategy and planning regarding a large array of modern treatment options. With the advent of wound vacs, improved macrovascular and microvascular vessel repair techniques, free flap transfers, and improved antibiotic and medical management strategies, more limbs are being salvaged.^{14,15,16,17,18} Surgeon bias and lack of available resources, particularly vascular team availability, can be important factors. In a study of young patients with amputations that occurred during military service, the main reason for an immediate or primary lower extremity amputation following trauma appears to be prolonged loss of circulatory status, especially with crush injuries to popliteal or posterior tibial vessels.¹⁹

Prolonged or unrecognized compartment syndrome with perfusion loss in comatose or obtunded individuals can necessitate an amputation early in treatment. With reasonable perfusion
or the ability and team resources to obtain perfusion, reconstruction or limb salvage should be the initial approach. Careful preoperative and surgical assessment must be carried out. Systematic débridement of open injuries with documentation of tissue viability, nerve loss, and bone loss is needed. Major nerve loss should not be regarded as a reason for amputation.²⁰ With PLM and farm machinery trauma, multiple surgical débridement procedures and assessments will be needed to eliminate multiple infective organisms.^5,21,22 It is expected that with high-velocity, explosion, or firearms trauma, tissue that initially appeared viable may not be. In children or adolescents, injuries severe enough to consider amputation may also involve damage to neighboring physes, other extremities, or organ systems. Children and adolescents have a more robust ability for wound healing after trauma than adults.²³

One of the most difficult challenges facing patients, families, and clinician is making the decision that an amputation will be required. The surgical team must understand that long-term outcome should be predicated on long-term function, not a mindset to preserve a limb at all costs. If the surgical team frames an amputation of a severely mangled extremity as an unsuccessful outcome, the family is deprived of crucial information.²⁴ A painful, insensate lower extremity with poor joint mobility and lacking durable skin coverage will likely be functionally inferior to a converted amputation. However, even though cosmesis is likely severely altered, a sensate or even partially sensate extremity with a plantigrade foot that can support walking and normal shoe wear is the key factor in successful reconstruction outcome. The distinction does blur because major trauma-damaged extremities are not identical (Figures 2, 3 and 4).

Studies comparing long-term follow-up of strictly pediatric patients undergoing traumatic major lower extremity amputation versus limb salvage are not available. Adolescent patients treated at pediatric centers are often lost to follow-up upon graduation. Pediatric patients are often blended in studies with adult trauma patients. Overall numbers of major lower extremity amputations in children following trauma are small. In Baldwin et al’s²⁵ multiple-center systematic review of 726 pediatric open fractures of the tibia, only 9 limbs required amputation. In one study comparing 18 patients with amputation versus 21 patients with microvascular reconstruction, reconstruction was thought to be better long term even though initial cost was higher.²⁶ In contrast, another study comparing 27 patients who underwent limb salvage using free flaps with 18 patients with transtibial amputation noted that significantly more patients who had reconstruction considered themselves disabled²⁷ (P < 0.05). In Busse et al’s¹⁴ multicenter comparison of 384 limb salvage cases with 161 primary amputations, both groups were associated with high rates of self-reported disability, 40% to 50% with worsening over time. Functional outcomes from both groups were not significantly different and costs were significantly higher in the reconstructed group. Importantly, most of the patients in whom limb salvage failed would opt for early amputation if they could decide again. Ladlow et al²⁸ noted in a study of young adult patients injured during military service comparing reconstruction versus amputation that the group with unilateral amputation demonstrated significant functional advantage. It is important to distinguish success as not just tissue viability but patient functionality. This is particularly important in active pediatric patients with many decades of life remaining. Prosthetic advances with respect to materials, componentry, and socket design have also improved function in patients with an amputation, most notably at the transfemoral level.²⁹

Replantation of a fully amputated lower extremity in children is controversial. Anecdotal case reports in children with long-term follow-up are documented in the literature.^30,31 In a recent analysis of 50 years of replantation surgeries, fewer attempts and a decreased success rate have been noted in the United States with regard to all types of replantation.³²

If a decision is made to amputate a lower extremity in a child, regardless of level, Krajbich³³ listed the following important general guidelines:

It is valuable that the patient and family are educated in rehabilitation strategies and prosthetic choices. Visits from other children who have undergone amputation, psychological consultation, and presentation of the amputation as a good treatment option and not a failure are very helpful. Rehabilitative efforts that improve balance and ambulation need to be incorporated very early.³⁴

A severely mangled or injured foot may require more than a partial foot amputation. This is particularly true with extreme hindfoot trauma.³⁵ It is difficult to obtain long-term data of large numbers of pediatric or adolescent patients with a traumatic ankle-level amputation. Many children with traumatic ankle-level amputations are initially treated at community hospitals or trauma centers, not necessarily pediatric centers. In a systematic review by Braaksma et al,³⁶ of 238 children with Syme amputation 94% were congenital. It is of extreme importance that the surgical team consider Syme or modified ankle-level amputation such as Boyd rather than a transtibial level amputation.³⁷ Although the usual surgical flap is posterior in a Syme or Boyd amputation, in trauma all possibilities should be considered, including anterior, medial, lateral, or sagittal flaps, to avoid transtibial level amputation. Transtibial amputations in children will generate a vexing array of complications, including diminished residual limb growth, bony overgrowth, and angular deformity, which are discussed in the next section. Ankle-level amputations are well tolerated in children with excellent survivability into adulthood.^38,39,40

Usual surgical details of the Syme and Boyd amputation have been described. Figure 5 shows details of the posterior flap as described by Wagner.⁴¹ In the Syme amputation it is important to keep the talocalcaneal dissection on bone, particularly medially to avoid vascular damage. Removal of the Achilles tendon from the calcaneus should be done carefully to avoid buttonholing through the skin; all parts of the calcaneus should be removed. Leaving residual calcaneal apophysis is common and may lead to a more bulbous residual limb or heel pad migration. In trauma, modifications may often be necessary. Frequently, inadequate skin coverage occurs. Malleolar excision may help in wound
closure. In PLM and farm machinery trauma, multiple contaminating organisms may be anticipated^5,21,42,43 and multiple surgical débridements needed. After final wound débridement has been accomplished, the team should not be reluctant to use split-thickness skin graft if needed. It has been shown by Parry et al⁴⁴ that the presence of skin grafts on a child’s amputated limb does not adversely affect outcome or cause greater prosthetic problems. Full-thickness coverage over weight-bearing areas may be accomplished in later staged procedures; anything that avoids the transtibial level in a child is a major success.

Although ankle-level amputations avoid the complications of transtibial levels, it is crucial to create an ankle-level amputation that is not too long. A pediatric Syme amputation is easier to fit and allows for more generally available prosthetic component options if somewhat shorter than the sound side. Morrison et al³⁹ recently documented this concept showing improved function in children with shorter residual limb Syme amputation in a study of 47 patients with Syme amputation. Others have published studies on this concept.⁴⁵ The Chopart amputation where talus and calcaneus are preserved can be very awkward to manage, as well as Syme or Boyd procedures, if tibial growth is normal on the amputated side. In adult groups, Chopart level ablation has been shown to create much difficulty in successful prosthetic fitting⁴⁶ (Figure 6). A shoe lift is often needed on the sound side. Fortunately, in children, length can be manipulated by physeal arrest.

Physeal arrest to improve prosthetic options, cosmesis, and potential function in the child with ankle-level amputation should be carried out at an age that will allow at least 4 to 6 cm of shortening. Green-Anderson-Messner charts⁴⁷ are used in this planning and have been shown to be very effective where proximal tibial and fibular physes are ablated.⁴⁸ This is often carried out during early adolescence (Figure 7). Drill ablation is the preferred method; however, both drill or screw physeal arrest has shown similar outcomes in nonamputee patient groups.⁴⁹ To avoid varus deformity or proximal fibular migration, proximal fibular arrest is also recommended. It has been shown that if less than 2 years of growth remain, proximal fibular arrest may not be needed.⁵⁰

Physeal arrest should be done with caution in young children in light of higher risk of complications, including asymmetric arrest and rare articular deformity possibilities.⁵¹ A criticism of physeal arrest in the patient with Syme amputation is the possibility of decreasing ambulation without a prosthesis. It has been shown that after age 11 years in the child with Syme amputation, there is a general lowering of ability to walk without a prosthesis, also dependent upon walking environment.⁵² Physeal arrest can be done distally at the ankle, but care must be taken not to create a distal tibial-fibular synostosis. Following severe trauma, a spontaneous synostosis may also occur at the ankle. In young children, a varus knee deformity can result from the distal tibial-fibular synostosis⁵³ (Figure 8).

Severe hindfoot and plantar trauma such as shredding or explosion injury can present difficulties as the usual flap for a Syme procedure may not be possible. In such cases, calcanectomy with secondary tissue coverage or primary Syme amputation using anterior flap are options.⁵⁴ Atesalp and Yildiz⁵⁵ described using the anterior flap Syme procedure successfully in 42 cases of
landmine trauma after primary radical débridement. In cases so severe that no reasonable attached flap is present, free flap coverage has been successfully incorporated in large heel defects in primarily nonamputee groups.^56,57,58 Cross leg flap may be considered and has shown success in salvage of a Syme residual limb in a 5-year-old child.⁵⁹

Complications of Syme procedures include posterior heel pad migration, a condition not seen in Boyd procedures.⁴⁰ Most of the heel pad migration cases in children often seen in congenital fibular deficiency diagnoses can be accommodated with prosthetic modification. Neuroma formation in a pediatric ankle-level amputation residuum appears to be rare, an advantage of ankle-level ablations. In the systematic literature search by Braaksma et al³⁶ that included 238 children with Syme amputation, no neuromas were reported.

Postoperative care is of major importance in an injury so severe as to create an ankle-level amputation. Most of these wounds are left open initially; however, negative-pressure wound therapy devices have been shown to be useful in the amputated extremity^17,60,61 and can be incorporated into a rigid or semirigid dressing. In children, early dressing changes should be done under anesthesia with appropriate re-débridement and wound assessment as needed. Regional anesthesia applications are particularly important in these children.⁶² After the wound is closed and a final rigid or semirigid dressing applied, the wound should not be inspected until follow-up in clinic. Interval semirigid dressings can continue for 4 to 6 weeks followed by residual limb shrinker dressings and a lightweight temporary prosthesis (Figure 9).

Final prosthetic choices in patients with an ankle-level amputation are more limited than with transtibial levels because of limited space for the foot and ankle component. In the new amputee, keeping the early prostheses light and easy to don and doff is important for early activity. In the early postoperative interval, a windowed socket may be needed to accommodate swelling and, in some individuals, useful long term. Capability of improved ankle motion with a modular design has been noted in multiple different prosthetic devices.⁶³ Overall functional differences between children with transtibial dynamic response components versus patients who have undergone Syme amputation with less
mobile ankle and foot components are small; both groups fortunately function at high levels. Studies show that the increased ankle motion seen in the high-performance feet does not reflect in peak power advantage or Pediatric Outcomes Data Collection Instrument sports/physical subscale.⁶⁴

If an injury in a child or adolescent is thought to be serious enough to require a diaphyseal or transtibial amputation, the team providing treatment as well as patient and family need to be prepared for complications that can continue through the entire pediatric lifespan. This section will systematically describe potential complications and appropriate solution options. Transtibial-level amputation in children and adolescents represent a high percentage of patients undergoing major traumatic lower extremity amputation.^2,5 In a blended study of all major lower extremity traumatic amputations carried out in the United States from 2011 to 2012, 48% were transtibial.¹⁵

Pediatric patients undergoing transtibial procedures function at a level nearly equal to the ankle-level amputee.⁶⁴ This reflects the importance of a functional knee joint in both groups. Once the knee is lost, gait velocity has been shown to significantly decrease and metabolic costs increase.^64,65 Preservation of the knee is thus a mantra in the treatment considerations of patients undergoing transtibial-level amputation.