Many PFAs result from injuries caused by a PLM. PLM injuries, however, have gone down in a 25-year study of US emergency departments.¹⁰ In a multicenter review of 144 children with traumatic injuries caused by a PLM, Loder et al¹¹ reported that the toes were the most often injured part of the foot (63%), with most of the injured children being bystanders or passengers on riding mowers. The injury resulted in an amputation present on admission in 59 children, with an additional 8 children requiring an amputation before hospital discharge. Of the 67 amputations, 51 were PFAs (40 at the toe level, 5 at the transmetatarsal level, and 6 at the Chopart level). Children injured by riding mowers were generally younger than those injured by push mowers (mean, 5.4 versus 11.0 years, respectively). It has been established that in pediatric patients a bimodal pattern of PLM injury rates exist, with a peak around 2 to 3 years and a second peak around 14 to 15 years. Back-over trauma is characteristic of the first peak, operator trauma the second.¹⁰ Adult operators of riding or push mowers often use hearing and eye protection and are unaware of the presence and impending danger to a nearby child. Loder et al¹¹ reported that 85% of foot injuries in children could be prevented if children younger than 14 years were not permitted to operate a push or riding PLM or be present in the immediate mowing area. The Amputee Coalition of America has compiled a checklist of precautions to prevent PLM trauma.¹²

Complications and unsatisfactory results are common after a PLM injury. Nearly 10% of the patients in the Loder et al¹¹ study had residual infection or osteomyelitis, and a 50% complication rate was reported. Infection from PLM trauma commonly involves multiple organisms, including bacteria, fungi, and mycobacteria.¹³ Daley and McIntyre¹⁴ reported that infecting organisms such as Stenotrophomonas maltophilia are common in PLM injuries, making it difficult to use empiric antibiotic therapies. Repeated surgical débridement is usually needed. Skin breakdown and amputation at a higher level occur at high rates.^15,16

The surgical team should evaluate the injured foot to determine the options for skin coverage and plan the final shape and functionality of the residual limb. Durable plantar skin should be saved whenever feasible (Figure 1). Physeal damage should be objectively assessed. Dormans et al¹⁷ proposed a simple classification system of lower limb PLM injuries. Type I is a shredding-type injury, and type II is a paucilaceration. All of the shredding-type injuries required amputation because of the difficultly of limb salvage. In the group with a paucilaceration injury, excellent results were achieved with more minimalistic procedures. In all groups, 4.9 procedures per patient were required.

Microvascular free flap reconstruction and composite tissue grafting have been successfully used in the distal lower limbs; however, these procedures have a complication rate of at least 62%.¹ Children treated with reconstruction involving free flaps within 2 days of injury had lower complication rates.¹ PFA with free flap reconstruction in pediatric patients is problematic because children have small blood vessels. It is important to recognize that donor-site composite grafts may increase in bulk as the child ages, creating a residual limb that cannot be placed in a shoe (Figure 2).

Negative-pressure wound therapy has been shown to be valuable in management of large, soft-tissue injuries to the foot and ankle.^2,3 Shilt et al³ specifically showed its effectiveness in PLM injuries in children. Incisional negative-pressure wound therapy has also been advocated.¹⁸ However, shredding-type foot and ankle injuries should be managed with a high degree of caution. Families should be advised of the high complication rates and the possibility that revision at a higher amputation level may be needed.

Attempting to salvage a foot that will not allow plantigrade ambulation
is a substantial problem in reconstruction of traumatic partial foot injuries. If the foot is in severe equinus, painful, and unusable after a successful composite free flap procedure, amputation at a higher level may be needed. This scenario is particularly common with traumatic PLM injuries. With loss of dorsiflexors, the need to immobilize the residual limb in a weight-bearing position is important. This becomes increasingly difficult in more-proximal foot amputations, such as those at the Lisfranc (tarsometatarsal) or Chopart (midtarsal) levels. If functional ankle dorsiflexion cannot be achieved, a Boyd amputation or Syme ankle disarticulation may be preferable at the initial surgery as opposed to later when additional subjective issues may play a role. A limb that heals in equinus can be one of the most difficult limbs to fit with a prosthesis (Figures 3 and 4).

A massive, shredding traumatic injury to the hindfoot can be a particularly difficult injury to manage when caused by a PLM or other machinery (Figure 5). Extensive hindfoot and intercalary loss can be managed successfully with a calcanectomy and a subsequent ankle-foot orthosis with a spacer block to substitute for heel loss.¹⁹ High failure rates can be expected with severe hindfoot salvage surgery.²⁰ Failure of a calcanectomy with an intact forefoot may require a Syme disarticulation with an anterior flap.

PFA in children frequently results from injuries sustained on a farm. In a series of farm-related injuries analyzed by Cogbill et al,²¹ 46% of the injuries were related to machinery and tractors, with the remaining injuries caused by animals or falls. In the Borne et al²² review of all pediatric amputations over a 5-year period, machinery was listed as the second most common mechanism with 18% being toe injuries. In a study by McClure and Shaughnessy²³ of farm injuries in children requiring amputation, all the injuries were open type IIIC Gustilo fractures and had polymicrobial contamination. In a 3-year study of farm injuries in 292 children, Lubicky and Feinberg²⁴ noted that most of the injuries occurred in the lower limbs and that the average age of the injured children was 11.9 years. Although the authors did not specify how many of the children required a PFA, they noted that 41 of 127 open fractures (32%) occurred in the tarsal or metatarsal toe areas.

The general principles of managing foot injury from farm-related causes are similar to those used in managing PLM trauma. The wounds are often infected with multiple contaminants, and multiple procedures are needed to achieve a successful residual limb. It is important to achieve durable skin coverage. Polfer et al²⁵ noted that split-thickness skin grafts may be successful in salvaging limb length but should be regarded as staging procedures. For farming families with limited financial resources, those who live in certain ethnic communities, and those with limited access to tertiary care centers, the ability to wear normal footwear is of utmost importance.²⁶

In a study by Loder²⁷ of 256 traumatic amputations in children, the third and fourth most common injuries involved motor vehicle and train-related trauma. Train-related injuries often occur in the process of boarding or jumping from a moving train. Although Loder²⁷ did not specify the incidence of PFAs from train-related trauma, 10 of 24 train-related injuries in his study occurred in the lower limbs. Because wounds from train-related injuries tend to be sharper and cleaner than injuries from PLM and farm-related trauma, fewer débridements may be needed and wound closure may be easier.