Essential Pearls On External Fixation Application

While external fixation has applications in multiple areas of foot and ankle surgery, mastery requires proper training and a strong understanding of the techniques. Accordingly, the authors share the latest information from the literature and their experience on the types of external fixation, and discuss key indications in trauma, elective surgery and limb salvage.

While the basic principles of external fixation have not changed much over the years, the available options have gradually evolved with newer technology. The three main categories for external fixation utilization in the lower extremity include traumatic/posttraumatic injuries, diabetic lower extremity reconstruction and elective surgery. For traumatic and posttraumatic injuries, one can use external fixation as a temporary or definitive device in the treatment of comminuted fractures, open fractures with soft tissue loss, fractures in a patient who is hemodynamically unstable or cannot undergo an open procedure, gunshot wounds and posttraumatic deformities. 

For diabetic lower extremity reconstruction, external fixation is ideal for the management of osteomyelitis and bone defects, complex arthrodesis, deformity correction including Charcot neuroarthropathy (see first photo above), and joint immobilization or surgical offloading after a soft tissue flap (see second photo above). In elective lower extremity surgery, external fixation is applicable in adult and pediatric congenital limb reconstruction, acquired deformities, limb lengthening, degenerative joint disease, equinus correction, non-union, malunion and revisional surgery.

External fixation is relatively contraindicated in patients who cannot withstand the procedure physiologically, patients at risk for non-adherence to the treatment and postoperative course, individuals with untreated moderate to severe peripheral vascular disease, a non-salvageable limb or the presence of internal hardware that prohibits proper wire or pin placement.

One can divide external fixators into several categories including pinless, linear, tube-to-bar, circular, hybrid and spatial frames.¹ The linear external fixation device includes the commonly used monolateral type, which remains on one side of the stabilized limb. The tube-to-bar external fixator includes the biplanar orientation, which is common with the “delta” configuration. Circular external fixators are multiplanar and are inherently the most stable. The hybrid external fixator is a combination of a unilateral and circular frame, which surgeons can modify based on the given pathology (see third and fourth photos above). Each type of external fixation may also supplement any internal fixation when necessary. 

A Closer Look At The Role Of External Fixation In Trauma and Posttraumatic Injuries 

Surgeons frequently use external fixation for high-grade traumatic and gunshot injuries that result in open or closed fractures with extensive soft tissue compromise. In open fractures, external fixation allows for anatomic reduction, stable fixation and access to extensive soft tissue damage for continuous monitoring and/or staged surgical interventions. In closed fractures with extensive soft tissue compromise, external fixation further allows for preservation of blood supply through percutaneous techniques. In the treatment of intra-articular calcaneal fractures, external fixation may limit potential complications such as flap devascularization, wound dehiscence and infection.  

Kissel and colleagues demonstrated successful results in patients treated for high-energy intra-articular calcaneal fractures via ligamentotaxis using a delta frame construct.² Additionally, Zgonis and team advocated for the use of Ilizarov circular external fixation for management of intra-articular calcaneal fractures with severe soft tissue trauma.³ With the increased rate of morbidity reported in open treatment of diabetic ankle fractures, DiDomenico and coworkers reported on a safe alternative using external circular ring fixation in vascularly compromised patients with diabetes and unstable ankle fractures.⁴ Polyzois and colleagues described an open distal tibial fracture they managed through Ilizarov circular external fixation with simultaneous distraction osteogenesis and the Papineau technique.⁵

One may also utilize unilateral versus circular external fixation for distraction and restoration of impacted bone depending on the anatomic location of the osseous structure involved in the traumatic injury. Allogenic bone grafting versus autogenous bone grafting, with or without plate bridging may be an option as a second staged procedure. In the treatment of posttraumatic arthritis, arthrodiastasis is a joint-sparing alternative to arthrodesis. Ankle arthrodiastasis with circular external fixation is a viable option in the treatment of posttraumatic ankle arthritis. Badahdah and Zgonis suggested that this procedure facilitates cartilage repair through mechanical unloading of the joint surface and restoration of intermittent intra-articular hydrostatic pressure.⁶ Ankle arthrodiastasis with external fixation is also compatible with other surgical techniques for further soft tissue and/or osseous deformity correction that may be necessary in complex trauma cases.

What The Literature Reveals About Ex-Fix Use In Elective Foot And Ankle Surgery 

As first described by Charnley, external fixation has been a useful modality for complex arthrodesis.⁷ In a cadaveric study, Ogut and colleagues demonstrated similar ankle fusion site stability with external ring fixation versus an optimized screw fixation technique.⁸ The authors subsequently concluded that external fixation can be a viable option in cases of complex ankle pathology that preclude the use of internal fixation (see fifth photo above). Easley and team demonstrated clinical benefits of ankle arthrodesis using circular external fixation for patients with insufficient bone quality to support internal fixation, in the presence of large amounts of avascular bone, or for patients with a history of osteomyelitis.⁹ For triple arthrodesis, Treadwell reported positive outcomes with the use of rail external fixators in eight patients and emphasized that this technique allows immediate axial loading and unrestricted ankle joint mobilization.¹⁰ 

One may also consider external fixation in certain scenarios for smaller joints such as arthrodesis of the first metatarsophalangeal joint. Stapleton and colleagues reported the use of a bone block joint distraction arthrodesis and external fixation for salvage of the first ray with concomitant gouty and septic arthritis.¹¹ External fixation is often the fixation of choice for revisional arthrodesis procedures due to suboptimal bone quality. Additional uses for external fixation in limb lengthening or deformity correction may include equinus or severe burn contractures due to the ability to facilitate gradual manipulation with frame adjustment.

Examining External Fixation In Diabetic Limb Salvage

In comparison to internal plates, screws and intramedullary nails, external fixation causes less disruption of soft tissue, osseous blood supply and periosteum. Accordingly, this approach is ideal for use in patients with diabetes who may have compromised healing potential. Similar to external fixation for arthrodesis in cases of suboptimal bone quality, circular external fixation is currently a popular option for the treatment of Charcot neuroarthropathy with or without osteomyelitis.^12-14 Cited benefits include a minimally invasive technique that preserves the anatomic architecture, limits neurovascular compromise and allows partial weightbearing when indicated.  

Furthermore, through proper surgical technique, external fixation is compatible with internal fixation when necessary.¹⁵ The temporary nature of the pins and wires makes external fixation ideal for providing bony stability in the setting of osteomyelitis, and the ability to completely avoid putting fixation into the infected area is equally beneficial. External fixators are particularly helpful in obtaining solid fusions of joints with recurrent osteomyelitis and therefore become the fixation of choice in cases involving previous failure of internal fixation.

With increased soft tissue reconstruction in patients with diabetes undergoing treatment for Charcot neuroarthropathy and/or osteomyelitis, external fixators may facilitate surgical offloading for any lower extremity flap that might not receive adequate protection from traditional splinting and/or casting (see sixth photo above). In addition to imparting superior stability to the foot and ankle, this technique, specifically with circular external fixation, allows easy access to the site for post-operative care and monitoring, and the ability to perform other simultaneous deformity correction.^16,17

In Conclusion

The significant impact of external fixation in lower extremity surgery for trauma and reconstruction stems from the sheer versatility of these devices. While there are numerous benefits for the use of external fixation, these techniques also come with a steep learning curve and are not without complications.  Therefore, focused surgical training and experience with external fixation is paramount for positive outcomes. Although external fixation has a fairly well-established role in trauma surgery, further clinical studies on the use of external fixation in diabetic foot and ankle surgery are necessary to shed light on the optimal use of this modality in this complex population.

Dr. Sohrabi is a Specialist and Fellow in Reconstructive Foot and Ankle Surgery within the Division of Podiatric Medicine and Surgery in the Department of Orthopaedics at the University of Texas Health San Antonio in San Antonio, Tx.

Dr. Ramanujam is an Associate Clinical Professor and Chief of the Division of Podiatric Medicine and Surgery in the Department of Orthopaedics at the University of Texas Health San Antonio in San Antonio, Tx.

Dr. Zgonis is a Professor and the Externship and Fellowship Director in Reconstructive Foot and Ankle Surgery within the Division of Podiatric Medicine and Surgery in the Department of Orthopaedics at the University of Texas Health San Antonio in San Antonio, Tx. He is the Founder and Scientific Chairman of the Annual International External Fixation Symposium (IEFS) in San Antonio. Dr. Zgonis is the editor of Surgical Reconstruction of the Diabetic Foot and Ankle (Second Edition) and co-editor of External Fixators of the Foot and Ankle.  

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