In severe forefoot trauma, the use of external fixation confers the benefits of osseous stabilization and relief of soft tissue strain in the setting of complicated open fractures, mangled soft tissue, compromised vascularity, and compartment syndrome. This chapter discusses specific forefoot case scenarios in which external fixation may be required and details the techniques and designs of the external fixators applied. External fixation can be utilized acutely for osseous stabilization in forefoot trauma and may be further utilized for staged reconstructive procedures such as arthrodesis, staged bone grafting, or distraction osteogenesis to manage metatarsal bone defects. The technical pearls described incorporate basic external fixation techniques and emphasize appropriate pin placement and external fixation designs that adequately stabilize the zone of injury. Many of these concepts and external fixation designs for forefoot trauma have gained popularity in the management of forefoot injuries sustained during war conflicts.

In the forefoot, external fixation is most appropriate for select high-energy trauma such as severely comminuted metatarsal fractures, fractures associated with compartment syndrome, Lisfranc’s fractures/dislocations not amenable to internal fixation, gunshot wounds/blast injuries, and severe soft tissue injuries that require both splinting and frequent evaluation of the affected soft tissue envelope. Blast injuries with significant soft tissue compromise, compartment syndrome, and pulverized fracture patterns are encountered among the surgeons treating combat injuries during time of war conflict. Likewise, hunting accidents, industrial accidents, crush injuries, and other mangled forefoot traumas may present with similar pathology that may require external fixation.

Relative contraindications for external fixation of forefoot trauma include fractures (with or without soft tissue injuries) that can be adequately stabilized with standard fixation, splint, or a prefabricated fracture shoe or boot. The majority of forefoot trauma, other than the case scenarios previously mentioned, can be addressed more effectively with percutaneous pinning or primary open reduction and internal fixation (ORIF). If soft tissue edema or fracture blisters are present on initial evaluation, then a well-padded lower extremity compressive dressing and splint is applied and standard ORIF follows within 3 to 14 days once the soft tissue envelope quiesces.

Unlike rearfoot and ankle, trauma to the forefoot may, at times, preclude spanning external fixation. Since placement of half-pins must avoid areas of devitalized tissue, open wounds, and/or planned incisions, in certain cases, there is limited space available for the proper use of an external fixator. In these instances, joint and fracture reduction and stabilization may be better achieved with the utilization of percutaneous pinning or external splints. In addition, extreme caution is needed in applying an external fixator to stabilize severe forefoot trauma when the vascular supply to the affected toes may be compromised. Slight overdistraction may induce irreversible vascular injury of the digital arteries and result in tissue loss and/or amputation.

Lastly, relative contraindications for external fixation in the forefoot include, and are not limited to, patients who suffer serious psychiatric illnesses or lack the social support or capability to handle the protracted recovery and specific care inherent to external fixation.

In any traumatic setting, evaluation of the surrounding soft tissue envelope is crucial. Salvage of the severe high-energy forefoot trauma depends largely on the degree of soft tissue loss and vascular injury as opposed to the extent of osseous damage. For this reason, approaches for salvage and final outcomes for blast injuries, lawn mower injuries, and industrial crush injuries involving the forefoot are usually dictated by the overall management of the soft tissue envelope.

Injury to individual toe(s) may vary in severity and the surgeon needs to determine which toes should be amputated and which should be salvaged. Attempts are usually made to salvage the hallux and first metatarsal, if feasible, with the primary goal
of restoration of near-normal push off during gait. Primary fusion of the first metatarsophalangeal joint with or without structural bone grafts is usually required for comminuted intra-articular fracture patterns. Salvage of the lesser toes may be difficult to achieve in the presence of poor soft tissue coverage and/or severe vascular compromise. In these cases, primary amputation may be preferred. Rare cases of external fixation application for salvage of lesser toes have been described but are not routinely performed. Particular attention must be given to forefoot injuries with large soft tissue defects, bone loss, and/or arterial injury because these may be best treated with partial foot, Symes, or major limb amputation to avoid a resultant painful, infected, or nonfunctional foot.

If lower extremity salvage is feasible, the stabilization of unstable fracture patterns is critical for soft tissue quiescence. Practically, planned pin placement must avoid any fracture blisters and be sufficient distance away from any open fracture fragments. When possible, placement of half-pins should also avoid skin bridges between incisions placed for fasciotomies as this may preclude future attempts at delayed primary closure. As often as possible, one of the dorsal fasciotomy incisions can be closed with delayed primary closure and the others closed with a split-thickness skin graft.

In addition, the surgeon must be aware of relative safe zones for pin placement and understand that unstable fracture patterns may become further displaced while inserting half-pins. At times, small limited incisions are required to place bone clamps, elevators, or retractors against the osseous segment for counterpressure during the placement of the half-pin. In the forefoot, this is commonly seen with pin placement in the distal fragment of severely comminuted metatarsal fractures.

With high-energy forefoot trauma, the stabilization of the medial, central, and/or lateral columns needs to be determined and addressed. Medial column stabilization typically involves spanning and/or stabilization of the first metatarsal. It is important to consider stability and alignment across the tarsometatarsal joint as well. Blast injuries or bone defects of the first metatarsal are best stabilized with half-pin(s) in the tarsal bones, in the proximal and/or distal first metatarsal (dependent on the fracture pattern), and in the proximal phalanx of the hallux. Central metatarsal bone defects and/or comminuted fracture patterns are best stabilized with medial and lateral column spanning external fixation that can be conjoined with either transfixing pins internally or a bent bar apparatus externally. Lateral column instability results from fracture patterns or bone defects involving the fourth and/or fifth metatarsal(s) or fracture–dislocations involving the tarsometatarsal joints. Laterally, external fixation is best achieved with half-pin(s) in the cuboid and/or calcaneus, and in the proximal and distal aspect of the fourth and/or fifth metatarsals (depending on the fracture pattern). Half-pins are typically avoided in the fourth and fifth toes as the phalanges are typically too small to secure adequate fixation and vascular compromise of these toes is not infrequent.

Lisfranc’s fractures and dislocations that necessitate external fixation require specific attention to stabilize the medial, central, and lateral columns and create a construct that prevents subluxation and motion across the tarsometatarsal joint. Often, additional percutaneous and/or internal joint pinning is required to ensure reduction of the tarsometatarsal joint complex. This is particularly evident with complete homolateral Lisfranc’s dislocations (Clinical Cases I–IV).

External fixation may also be utilized for distraction purposes to facilitate bone grafting and/or ORIF or arthrodesis for bone loss associated with metatarsal fractures. In these case scenarios, the external fixation is beneficial in achieving fracture reduction and alignment while simultaneously restoring the length to the metatarsal. With open fractures, metatarsal bone defects are often initially managed with serial surgical debridements and antibiotic-impregnated cement spacers to avoid deep infection until wound healing occurs. It is often beneficial to evaluate the contralateral uninjured foot to determine the appropriate length of the metatarsal. In addition, marginal sacrifice of metatarsal length is beneficial, as complete restoration of the length may lead to vascular compromise of the affected toe. In these cases, fixation is obtained by placing two half-pins proximal to the bone defect in the metatarsal and/or tarsal bone and one to two additional half-pins distal to the bone defect. A half-pin can usually be placed into the hallux and into the proximal phalanges of the second and third toes without complications. Pinning of the lesser digits across the metatarsophalangeal joint is often required to prevent iatrogenic toe contractures.

As mentioned, metatarsal bone defect reconstruction begins after wound closure is successful and infection has been avoided. After explantation of the antibiotic-impregnated bone spacer or beads, several strategies for bone defect reconstruction are available: Allogenic structural grafting, autogenous structural grafting, Papineau technique, or bone transport. Distraction osteogenesis and bone segment shortening with or without arthrodesis have a role in management of metatarsal bone defects. Staged reconstructive procedures typically are not performed until several weeks from the initial injury to avoid deep infection. The spanning external fixation system typically utilized can be removed if bone grafting can be performed with supplemented internal fixation. The external fixator is maintained or further modified if bone shortening, distraction osteogenesis, or Papineau is performed. Arthrodesis can be performed with or without external fixation and the condition of the surrounding soft tissue envelope is typically the deciding factor.