Ankle-spanning external fixation is a common surgical tactic that can be used for multiple indications in the lower extremity. Such indications include open and unstable fracture-dislocations of the ankle, as well as management of soft tissue injuries around the foot and ankle. Ankle-spanning external fixators have also gained popularity as a staged protocol in the treatment of distal tibia intraarticular, or pilon, fractures. These injuries were historically associated with high complication rates, before the advent of temporizing stabilization with an ankle-spanning frame.1,2 The application of such fixators allows the fractures to be reduced by ligamentotaxis, therefore permitting improved preoperative planning of definitive reconstruction.1,2
The traditional configuration of the ankle-spanning external fixator is the “delta frame.” Its application consists of half-pins into the anterior tibia, connected to both sides of a transfixation pin through the calcaneal tuberosity. However, because of the pin position in the posterior aspect of the calcaneal tuberosity, the traction vector is not directly caudal. Therefore, it may be difficult to accurately keep the talus reduced underneath the tibial plafond in the sagittal plane in severely unstable injuries (Figure 1). Additionally, midfoot and forefoot stability is often needed with pin placement into the first and fifth metatarsal, or the medial cuneiform.3 This extension of the traditional delta-type frame is important to maintain the foot in neutral position and prevent equinus deformity as a result of Achilles contracture; these pins act as a more rigid alternative to posterior splinting. Elevation is an important aspect of the soft tissue stabilization and recovery. However, sustained and safe elevation can be difficult with an external fixator. Clinicians will often place pillows or sheets underneath the affected limb, but this is not reliable because these items can be removed during transfers. Additionally, allowing the affected extremity to lie on a surface during the staged protocol may create an undue decubitus lesion.
Side view of the foot in equinus position due to lack of metatarsal pins. The absence of “kick-stand” bars forces the foot to rest on the pillow, which can be readily removed. This puts the foot at greater risk for heel decubitus ulcerations.
An important modification is a “kickstand” applied to the external fixator for more reliable, sustained, and comfortable elevation of the affected extremity. The authors describe a practical and strategic modification of the delta frame configuration. This “steering wheel” technique allows the surgeon to better manipulate the fracture to restore length, rotation, and alignment.
The patient is administered general anesthesia in the supine position on a well-padded radiolucent table. The C-arm is placed on the side of the room contralateral to the operative lower extremity. The monitor should be at the foot of the bed in the surgeon's direct line of sight. Nonsterile blankets, bumps, or foam may be used as necessary to allow the ipsilateral patella to point toward the ceiling (Video).
Prior to beginning the procedure, it is helpful to arrange the anticipated hardware in an organized fashion on a Mayo stand. An adequate number of pins, bars, clamps, and outrigger posts must be available. To reproduce this technique, there should be two 5-mm half-pins, one 5-mm calcaneal transfixion pin, one 4-mm half-pin, one 3-mm half-pin, four bars with lengths to be determined, one multi-pin clamp, two outrigger posts, four pin-to-bar clamps, four bar-to-bar clamps, and appropriate wrenches (Figure 2). Care must be taken to ensure that the bars are of adequate length to span from the fore-foot to the tibial pins.
Prepared Mayo stand with two 5-mm half-pins, one 5-mm calcaneal transfixion pin, one 4-mm half-pin, one 3-mm half-pin, four bars with lengths to be determined, one multi-pin clamp, two outrigger posts, four pin-to-bar clamps, four bar-to-bar clamps, and appropriate wrenches.
Prior to placing the pretibial pins, the incisions are marked proximal and away from definitive fixation and the zone of injury. Using fluoroscopic guidance will facilitate delineating the proximal extent of the fracture and eventual placement of definitive internal fixation. The tibial crest should be palpated and marked out anteriorly, and two small stab incisions the same size as the 5-mm half-pins should be made along the anterior tibia, just medial to the crest. The authors recommend using half-pins that are self-drilling and self-tapping. However, if desired, one can pre-drill for the half-pins. Care must be taken to avoid skiving off the anterior-medial cortical surface of the tibia; the surgeon can start the pin perpendicular to the anterior-medial face of the tibia to initiate cortical purchase and then lift the hand before the threads catch to the vector initially desired to gain appropriate bicortical access. A multi-pin clamp with a drill guide in the appropriate location is then fashioned over the first half-pin. This clamp acts as a guide for second tibial half-pin placement as it is placed through the aforementioned drill guide. A dimple is created in the skin to mark the proposed surgical stab incision. Placement through this guide will ensure that it later fits in the clamp and can be locked in place. The depth must be checked on a lateral view under fluoroscopic intensification. The half-pins are advanced or backed out as necessary using hand instrumentation. The use of tapered half-pins is not recommended due to the loss of purchase if the half-pin is reversed. The multi-pin clamp is now tightened with a wrench, and the outrigger posts are placed on the multi-pin clamp.
The fluoroscopic intensifier is then brought distally in the lateral position to view the calcaneus for placement of the calcaneal transfixion pin. Understanding of the neurovascular anatomy of the tarsal tunnel is critical to avoid violation of these structures.3 A calcaneal transfixion pin is placed from medial to lateral, with the target being posterior to the halfway point of a line drawn from the posterior-inferior calcaneus to the inferior-medial malleolus.4 The trajectory of this pin should be parallel to the plantar surface of the foot and perpendicular to the calcaneus. The surgeon must drill through to the lateral skin, continuing to insert the pin until the center threads are buried within the calcaneus.
To obtain full control of the foot, a 4-mm half-pin is placed in bicortical fashion in the medial aspect of the base of the first metatarsal. Alternatively, this pin may be placed into the medial cuneiform. A lateral 3-mm half-pin is then placed into the lateral aspect of the proximal metaphysis of the fifth metatarsal in bicortical fashion (Figure 3). Alternatively, this pin may also be placed into the cuboid. Similar to the calcaneus pin, the metatarsal pins are placed parallel to the plantar surface of the foot. The pin-to-bar connections are placed to the calcaneal and metatarsal pins, and the bar-to-bar connections are placed on the tibial multi-pin clamp apparatus. The bars are placed into the connection clamps of the metatarsal and calcaneus pins, creating a distal steering wheel. The clamps are first tightened by hand and then by T-handle and/or ratchet wrenches. The medial and lateral bars should extend posteriorly past the posterior aspect of the heel. The goal of this extra-long bar placement is to act as a kickstand while the patient is lying supine in bed. Appropriate-length bars should be used to achieve approximately 5 to 6 cm of clearance from the contact surface. This will suspend the foot in the air, preventing the heel from resting on the bed. The lateral post should extend more posteriorly than the medial post such that the resting position of the leg offsets the external rotation of the native hip (Figure 4).
Placement of the calcaneus transfixion pin and metatarsal pins. The medial pin can be alternatively placed in the medial cuneiform and the lateral pin may be alternatively placed into the cuboid.
The “kickstand” modification. The posts extend posteriorly to suspend the foot off the resting surface. The lateral post is placed more posteriorly to counter the natural external rotation of the leg.
The remaining bars and clamps are placed to connect the distal steering wheel to the tibial pins prior to reduction. The surgeon should hand-tighten only enough to prevent the bars from disassembling. Overtightening at this stage will prevent adequate reduction. The subsequent part of the procedure requires an assistant surgeon and the surgeon: one obtains the reduction and the other tightens the clamps. The surgeon at the foot of the bed obtains the reduction by driving the bars of the external fixator akin to a steering wheel. This bar orientation allows the surgeon to readily flex/extend, provide varus/valgus, compress/distract, or internally/externally rotate as the reduction requires. Care must be taken to place the foot at 90° to the leg to prevent equinus contracture (Figure 5). After confirmation of appropriate reduction under fluoroscopic intensification, the assistant surgeon tightens the clamps while the primary surgeon maintains the reduction. Final fluoroscopic images of the fracture reduction are obtained (Figure 6).
Views of the medial (A), lateral (B), and anterior (C) aspects of the leg and foot. The foot is 90° to the leg with the assistance of the metatarsal pins. The heel is suspended off the resting surface.
Anteroposterior (A) and lateral (B) fluoroscopic images of the ankle showing appropriate initial reduction of the fracture. This is facilitated by the “steering wheel” modification.
The tip of the sharp calcaneal transfixion pin is cut and a rubber covering is placed over top. Each stab incision must be tension free. Tension-relief incisions may be performed as necessary. The dressing of choice of the senior author (B.C.T.) is to wrap the pin sites with dry gauze. The pins are wrapped individually without crossing the foot or heel because pressure sores or wounds may develop. An elastic bandage is then used to overwrap the entire pin-to-bar construct and lower extremity. A computed tomography scan is obtained for surgical planning of definitive open reduction and internal fixation.
Pilon fractures occur as a result of high-energy mechanisms that are typically associated with significant soft tissue injury. Early surgery through this traumatized soft tissue envelope is not recommended due to the increased incidence of complications. McFerran et al1 reported on the complication rate associated with early open reduction and internal fixation of severe pilon fractures. Thirty-four percent of complex pilon fractures developed a wound complication, deep infection, or both. As a result of these unacceptable complication rates, alternative management strategies were developed.
To avoid such soft tissue complications, the soft tissue must be allowed to recover prior to formal reconstruction. In a study of 46 cases of type C pilon fractures, Sirkin et al2 managed these patients with a staged protocol. There was initial spanning external fixation and fibular plating when necessary. Formal reconstruction was delayed on average by 13 days. With this strategy, only one major complication was noted in 29 closed injures and two major complications were noted in 17 open injuries.2
The proposed benefits of the current technique are based on the medial and lateral foot-to-calcaneus bars, which act as a steering wheel to allow the surgeon to better manipulate the fracture reduction. This permits improved ability to reduce the fracture and simultaneously place the ankle in neutral position as the clamps are tightened. The metatarsal pins are used to facilitate placing the foot at 90° to the leg, as prevention of equinus contracture after pilon injuries has been reported to be an important consideration.5–9 The placement of a pin on the medial and lateral aspects of the foot acts to more evenly counteract the contracture of the Achilles tendon.
Inappropriate application of external fixators may leave the heel vulnerable to excessive pressure when the lower extremity rests on the bed.10,11 This is important because when adequate off-loading of the heel is not achieved, pressure changes may progress to full-thickness wounds and osteomyelitis.12 The long bars that extend posteriorly past the heel, as described in the current technique, allow the foot to be suspending off the bed and thus prevent heel decubitus ulcerations. The authors recommend the bars to allow the foot to elevate approximately 5 to 6 cm. This modification facilitates the reduction of soft tissue edema as the extremity is kept in an elevated position. Elevation of the lower extremity greater than this height may lead to excessive hyperextension of the knee. A soft pillow may be used to assist in popliteal relief as needed. Additionally, Gilcreast et al6 compared the efficacy of three different devices for the prevention of heel ulcerations. Bunny boots, egg crates, and foot waffle were not statistically different, although boots were the most cost-effective device. However, the use of these common off-loading devices is difficult when external fixation is in place and interferes with proper wound care.11,13
The application of a spanning external fixator can be successful as part of a staged protocol for the treatment of high-energy pilon injuries. The authors believe that this modification to the temporizing spanning external fixator is safe, efficient, and reproducible.
- McFerran MA, Smith SW, Boulas HJ, Schwartz HS. Complications encountered in the treatment of pilon fractures. J Orthop Trauma. 1992;6(2):195–200. doi:10.1097/00005131-199206000-00011 [CrossRef] PMID:1602341
- Sirkin M, Sanders R, Di-Pasquale T, Herscovici D Jr., A staged protocol for soft tissue management in the treatment of complex pilon fractures. J Orthop Trauma. 2004; 18(8)(suppl):S32–S38. doi:10.1097/00005131-200409001-00005 [CrossRef] PMID:15472563
- Barrett MO, Wade AM, Della Rocca GJ, Crist BD, Anglen JO. The safety of forefoot metatarsal pins in external fixation of the lower extremity. J Bone Joint Surg Am. 2008;90(3):560–564. doi:10.2106/JBJS.G.00743 [CrossRef] PMID:18310706
- Santi MD, Botte MJ. External fixation of the calcaneus and talus: an anatomical study for safe pin insertion. J Orthop Trauma. 1996;10(7):487–491. doi:10.1097/00005131-199610000-00007 [CrossRef] PMID:8892149
- Rozbruch SR. Posttraumatic reconstruction of the ankle using the Ilizarov method. HSS J. 2005;1(1):68–88. doi:10.1007/s11420-005-0113-3 [CrossRef] PMID:18751813
- Gilcreast DM, Warren JB, Yoder LH, Clark JJ, Wilson JA, Mays MZ. Research comparing three heel ulcer-prevention devices. J Wound Ostomy Continence Nurs. 2005;32(2):112–120. doi:10.1097/00152192-200503000-00008 [CrossRef] PMID:15867701
- Ho B, Ketz J. Primary arthrodesis for tibial pilon fractures. Foot Ankle Clin N Am. 2017;(22):147–161. doi:10.1016/j.fcl.2016.09.010 [CrossRef]
- Tomás-Hernández J. High-energy pilon fractures management: state of the art. EFORT Open Rev. 2017;1(10):354–361. doi:10.1302/2058-5241.1.000016 [CrossRef] PMID:28461913
- Dujardin F, Abdulmutalib H, Tobenas AC. Total fractures of the tibial pilon. Orthop Traumatol Surg Res. 2014;100 (1)(suppl):S65–S74. doi:10.1016/j.otsr.2013.06.016 [CrossRef] PMID:24412046
- Casey D, McConnell T, Parekh S, Tornetta P III, . Percutaneous pin placement in the medial calcaneus: is anywhere safe?J Orthop Trauma. 2004; 18(8)(suppl):S39–S42. doi:10.1097/00005131-200409001-00006 [CrossRef] PMID:15472564
- Castro-Aragon OE, Rapley JH, Trevino SG. The use of a kick-stand modification for the prevention of heel decubitus ulcers in trauma patients with lower extremity external fixation. J Orthop Trauma. 2009;23(2): 145–147. doi:10.1097/BOT.0b013e318196bb6a [CrossRef] PMID:19169108
- Bollinger M, Thordarson DB. Partial calcanectomy: an alternative to below knee amputation. Foot Ankle Int. 2002;23(10):927–932. doi:10.1177/107110070202301007 [CrossRef] PMID:12398145
- Chan R, Taylor BC, Gentile J. Optimal management of high-energy pilon fractures. Orthopedics. 2015;38(8):e708–e714. doi:10.3928/01477447-20150804-59 [CrossRef] PMID:26270758