When Traditional Offloading is not an Option, Could an External Fixator be a Solution?: A Case Report

Offloading is a cornerstone in managing diabetic plantar foot ulcers; however, it often represents one of the most challenging aspects of treatment for clinician and patient alike. The authors present a case of a 61-year-old African American man with type 2 diabetes and a limb-threatening plantar foot ulcer that required aggressive wound and surgical management.Due to the heavy drainage and patient adherence issues, traditional offloading techniques such as total contact cast, DH Pressure Relief Walker (Össur, Foothill Ranch, CA), and wedge shoes, among others, were not viable options. Without offloading, healing will be difficult to achieve and will take a long time, carrying a higher risk of limb loss. The decision was made to apply an Ilizarov circular frame with footplate to facilitate offloading and weight bearing in tandem with negative pressure therapy. Although this is still considered an unusual use of this device, the results were positive and the wound progressed to complete reepithelialization.

Monsen et al¹ have shown that approximately 25% of patients with diabetes will develop foot ulcerations during their lifetime, while a staggering 85% of lower limb amputations are preceded by a lower extremity ulcer.

Although amputation is perceived as an appropriate treatment option for addressing complex diabetic foot wounds and at times necessary, choosing this route often puts patients at risk of contralateral limb loss and a shortened life expectancy.² Aulivola et al³ found that the survival rate for below-the-knee amputations to be 74.5% and 37.8% at 1 and 5 years, respectively. Therefore, there have been a multitude of different algorithms and methodologies proposed in the literature to approach these ulcerations with the goal of preventing amputation.⁴ Snyder et al⁴ opine that reestablishing vascular blood supply, controlling infection, and offloading pressure forces remains a critical part of any limb preservation protocol.

The purpose of this case report is to stress the importance of pressure offloading surrounding diabetic foot ulcers (DFUs) and to highlight the authors’ use of an external fixator as a possible tool to accomplish this.

Presentation and medical history. A 61-year-old African American man with a known history of type 2 diabetes mellitus, peripheral arterial disease, and a history of multiple DFUs with osteomyelitis presented to Barry University Foot and Ankle Clinic at Jackson North Medical Center (Miami, FL) for follow-up on a recent incision and drainage performed on the plantar right foot. He had a history of 2 digital foot amputations and lower limb revascularizations (percutaneous translumenal angioplasty of the right peroneal artery with stenting) that had failed in great part due to nonadherence in taking antiplatelet medications. In addition, the patient is known to be noncompliant with nonweight-bearing instructions. Vital signs showed no fever or tachycardia. However, the right foot was red, hot, and swollen, and the wound was draining frank white pus with a foul odor. The wound initially measured 5 cm x 4 cm x 2 cm with a fibrotic base and probed to bone. Despite an insensate foot secondary to diabetic polyneuropathy, the patient complained of severe pain that was rated 8 out of 10 on the Numeric Pain Rating Scale. He was sent to the hospital immediately, where a basic metabolic panel and complete blood count revealed a white blood cell count of 14 × 10⁹/L, and glucose level of 230 mg/dL with a body mass index of 19.5 and hemoglobin A1c of 8.2%. Plain radiographs showed no soft-tissue gas or signs of osteomyelitis. After performing a local wound culture, the patient was started on intravenous vancomycin 1 g every 12 hours coupled with Zosyn 3.375 g intravenous every 6 hours (Pfizer, New York, NY) and taken to the operating room where deep debridement was performed down to the fascia and bone. Postoperatively, a noninvasive vascular study was performed, and the interventional radiology service was consulted. The patient had good blood flow in the right posterior and the anterior tibial arteries and poor flow in the right peroneal artery through a stenosed stent placed in the past, but no more invasive measures were recommended at that time.

Offloading. Three days following the initial surgery, the patient returned to the operating room for further debridement. Postdebridement measurements of the wound were 13.1 cm x 8.6 cm x 2 cm (Figure 1). The wound was irrigated with saline pulse lavage and covered by Integra Bilayer Wound Matrix (Integra, Plainsboro, NJ). An Ilizarov circular external fixator with footplate was applied on the lower leg, utilizing 3 tibial rings, half talar ring, and double footplates (Wright Medical, Memphis, TN). The proximal footplate was meant for posterior offloading, and the distal footplate was for plantar offloading. Continuous negative pressure wound therapy (NPWT) was then applied over the wound and set to 125 mm Hg (Figure 2). In light of the offloading method utilized, the patient was allowed to partially bear weight and transitioned to full weight bearing within 1 week following surgery. Patient was discharged from the hospital 6 days postoperatively.

Follow-up. The patient was seen twice weekly after the surgery for NPWT dressing changes. At that time, local wound care included cleansing with normal saline and sharp debridement. External fixation pin insertion sites were cleansed with alcohol on each visit and wrapped with iodine-soaked gauze. The patient remained fully weight bearing during the visits. Wound measurements were taken on each visit as outlined below (Figures 3, 4).

The intended time for external fixator utilization lasted until complete epithelialization of the wound. However, 4 months postoperatively the patient presented with severe pain at several of the pin sites, necessitating removal of all hardware in the operating room, where the wound was further debrided and covered with another wound matrix dressing. That was the patient’s third debridement procedure. At this juncture, a total contact case (TCC) was offered; however, the patient refused to use it and was subsequently placed in a controlled ankle movement (CAM) walker. Education regarding strict adherence to protocols was reinforced, and the patient was instructed to be wheelchair bound. Wound measurements were 5.6 cm x 5.6 cm x 1 cm (Figure 5). Negative pressure wound therapy was reapplied on 125 mm Hg continual pressure. Final wound closure was achieved 6 months following the initial surgery (Figure 6).

Different devices and techniques are available to offload DFUs, including removable and nonremovable devices, surgery, wheelchairs and crutches, and bed rest.⁴ However, choosing an appropriate device remains challenging in some cases.

The key in achieving the maximum benefits of an offloading device depends on patient adherence,⁵ and TCC is viewed as the gold standard in offloading plantar foot ulcerations.^6,7 One can also create an instant total contact cast (iTCC) by wrapping plaster or Coban Self-Adherent Wrap (3M, St. Paul, MN) around a removable device (ie, CAM walker) to make it nonremovable. A meta-analysis by Morona et al⁸ showed the iTCC methodology was comparable in effectiveness to a TCC. 

The present case highlights a patient who required an approach utilizing an external fixator with footplate to offload a complex plantar foot ulcer. Additionally, NPWT was required to address wound depth and manage copious exudate, which required frequent dressing changes. 

External fixation is usually used for Charcot reconstruction, complex deformity correction, trauma, and in the presence of osteomyelitis.^2,9 However, the literature is sparse in relation to the utilization of external fixators to offload plantar foot wounds. In a case report by Ramanujam et al,¹⁰ a circular external fixator frame was utilized to offload and immobilize the foot after skin flap surgery for 6 weeks, while allowing unimpeded observation of flap viability until wound healing was achieved. Additionally, Clark et al¹¹ presented 2 case reports utilizing the SALSA-stand technique where pins and rods were constructed to offload the foot and removed in the clinic after 4 weeks when healing had occurred. Clemens et al² reviewed 24 patients over 6 years, where both monoplanar and multiplanar external fixators were used solely to offload the lower extremity after soft-tissue reconstruction; patients were instructed not to bear weight on plantar flaps until flap maturation after 6 weeks. In their study, the average healing time was approximately 100 days.²  

Conversely, in the present case the external fixator allowed immediate weight bearing by adding an additional footplate while facilitating the use of concomitant NPWT.

The use of external fixation to offload plantar foot ulcers is currently limited due to a paucity of evidence, cost of the devices, knowledge, and experience. Patient selection, comprehensive preoperative planning, and surgical execution remain critical.

This case report shows utilization of external fixation is an effective alternative for offloading plantar DFUs in instances where traditional devices may be inappropriate or infeasible. However, it remains an advanced and new technique that should be performed by surgeons familiar with the methodology and potential complications. If the treating clinician is inexperienced with this technique, an outside surgeon should be consulted to help facilitate the use of this method if traditional offloading is not possible.