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Surgical Technique: Achieving Anatomic Alignment With Temporizing, Ankle-Spanning External Fixation

Liskutin, Tomas MD, MS*; Bernstein, Mitchell MD, FRCSC; Summers, Hobie MD; Lack, William MD

Author Information
Journal of Orthopaedic Trauma: August 2018 - Volume 32 - Issue - p S38-S39
doi: 10.1097/BOT.0000000000001205

Abstract

INTRODUCTION

External fixation (ex-fix) systems provide powerful tools for managing a variety of orthopaedic issues. In high-energy ankle injuries or in patients with specific soft tissue considerations, immediate definitive fixation may be deferred in favor of ex-fix to provide temporary stability and alignment. This staged treatment allows for soft tissue recovery before definitive surgery.1,2 Additionally, external fixation is frequently used in the setting of polytrauma and vascular injuries to allow prioritization of a severely injured patient's care. Furthermore, temporizing ex-fix allows for CT imaging after an anatomic alignment is obtained, allowing for more precise preoperative planning of definitive surgery.

For fractures about the ankle, joint-spanning ex-fix allows one to obtain anatomic alignment while providing stability, access for wound care, and soft tissue rest. Although a superior technique has not been concluded, a staged protocol with temporizing, joint-spanning ex-fix minimized infection rates for type C pilon fractures compared with historically reported rates with immediate definitive treatment,3 in addition to improving articular reconstruction and minimizing soft tissue complications.4 This video demonstrates surgical techniques for the application of temporizing, ankle-spanning external fixation using 2 cases.

CASES

Case 1 is a 26-year-old man who presented to Loyola University Medical Center after a motor vehicle collision and was found to have an isolated pilon fracture (AO/OTA 43B). Closed reduction was performed in the emergency department.

Case 2 is a 72-year-old woman transferred to Loyola University Medical Center 2 days after sustaining a low-energy bimalleolar ankle fracture–dislocation (AO/OTA 44B2). A closed reduction was performed at an outside hospital, but the ankle was dislocated when the patient arrived at our institution.

Both injuries resulted in severe soft tissue trauma about the fracture sites, as evidenced by ecchymosis, swelling, fracture blisters, and skin that would not wrinkle on examination. As such, the patients stood to benefit from application of ankle-spanning ex-fix, followed by acquisition of CT imaging to assist planning of definitive treatment.

SURGICAL TECHNIQUE

The patient is positioned supine on a radiolucent table with a bump and ramp under the ipsilateral thorax and leg, respectively, and C-arm in position. The lower extremity is prescrubbed with chlorhexidine and alcohol before a staged sterile prep and drape. A surgical timeout is performed, and anatomic landmarks are identified.

Before calcaneal pin placement, the ankle is further elevated with a small towel bump for improved access. The relative safe zone is identified by palpable landmarks5 or fluoroscopically, with the anterior border of this zone created by a plane that defines the calcaneal tuberosity (see Video, Supplemental Digital Content 1, http://links.lww.com/JOT/A380 at 4:39). If the subtalar joint is uninjured, fluoroscopic landmarks should be assessed with a view that includes a “perfect lateral” of the talar dome to reliably control rotation. The calcaneus is predrilled with a 3.5-mm bit in a trajectory perpendicular to the sagittal axis of the limb and parallel to the plantar surface of the heel. A 5.0-mm, centrally threaded pin is then inserted.

Next, attention is turned to the proximal tibial pin. An incision is made one-third of the distance between the anterior and posteromedial borders of the tibia, and a 3.5-mm bit is used to drill through both cortices in an anterior–posterior trajectory. A 5.0-mm half pin is placed by hand, with positioning confirmed fluoroscopically. A bar is then added to either side of the calcaneal pin and connected to the tibial pin, creating a “delta” configuration. Lap pads or T-handles are attached to the calcaneal pin to minimize the risk of injury at the sharp pin tip while reducing direct radiation exposure. Traction is pulled to restore length; 94% of polled OTA members agreed in a 2010 survey that it was the most important aspect of the reduction obtained with temporizing ex-fix.6 Secondarily, coronal and sagittal alignment can also be grossly addressed with this reduction maneuver.

Attention is now turned to sagittal alignment. One must appreciate that the longitudinal bars create a posteriorly directed vector, which may improve or worsen sagittal alignment, depending on the injury. A second tibial pin is placed, which will be used as a fulcrum against which to lever the existing frame. The frame is spanned with a crossing bar to create an “A” configuration, and a fixed point on the tibial pin (eg, pin-to-bar clamp) and lamina spreader are used to push this bar anteriorly or posteriorly, allowing for fine-tuned adjustments before securing the crossing bar to the distal tibial pin. This adjustment is most critical in cases of posterior dislocation that are difficult to fully correct with the posteriorly directed vector inherent to the frame orientation.

The last focus is coronal alignment, which may or may not be acceptably aligned from the initial reduction maneuver. The calcaneal pin-to-bar clamps can be loosened to make any adjustments necessary, again using a fixed point (eg, clamp on the calcaneal pin) to lever against to allow for fine, controlled adjustments. Final imaging is obtained to confirm pin position and alignment with the frame then wrapped in ace-bandage to reduce visual shock to the patient. The patient remains non–weight bearing and is encouraged to elevate the extremity until their definitive surgical treatment.

DISCUSSION

Temporizing, ankle-spanning external fixation is a dynamic tool in the management of injuries about the ankle and is particularly beneficial for patients with severe soft tissue injury. With a systematic approach, ankle-spanning external fixation can be used to obtain anatomic alignment with restoration of the length and a congruent ankle joint.

REFERENCES

1. Court-Brown CM, Heckman JD, McQueen MM, et al. Rockwood and Green's: Fractures in Adults. 8th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2014.
2. Bible JE, Mir HR. External fixation: principles and applications. J Am Acad Orthop Surg. 2015;23:683–690.
3. Sirkin M, Sanders R, DiPasquale T, et al. A staged protocol for soft tissue management in the treatment of complex pilon fractures. J Orthop Trauma. 2004;18(suppl 8):S32–S38.
4. Patterson MJ, Cole JD. Two-staged delayed open reduction and internal fixation of severe pilon fractures. J Orthop Trauma. 1999;13:85–91.
5. Casey D, McConnell T, Parekh S, et al. Percutaneous pin placement in the medial calcaneus: is anywhere safe? J Orthop Trauma. 2004;18(suppl 8):S39–S42.
6. Collinge C, Kennedy J, Schmidt A. Temporizing external fixation of the lower extremity: a survey of the orthopaedic trauma association membership. Orthopedics. 2010;33(4). doi: 10.3928/01477447-20100225-04.
Keywords:

external fixation; ankle fracture; pilon fracture

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