External fixators for elective rearfoot and ankle arthrodesis

Clin Podiatr Med Surg 20 (2003) 65 – 96

External fixators for elective rearfoot and ankle arthrodesis Techniques and indications Stanley Kalish, DPM, FACFASa,c, Justin Fleming, DPMb,*, Robert Weinstein, DPMb a

Emory Northlake Regional Medical Center, The Podiatry Institute, 6911 Tara Boulevard, Jonesboro, GA 30236, USA b Emory Northlake Regional Medical Center, The Podiatry Institute, 1459 Montreal Road, Suite 206, Tucker, GA 30084, USA c Atlanta Foot and Leg Clinics, 6911 Tara Boulevard, Jonesboro, GA 30236, USA

Though the concept of external fixation began with Hippocrates, Malgaigne is credited with development of the first external fixator in 1840, designed for open fracture management [1]. Perception and application of external fixation subsequently took various forms, such as Parkhill’s plate/clamp fixator [2], Lambotte’s threaded half-pin-clamp-rod device [3], and Anderson’s adjustable external fixator [4]. A thorough biomechanical description of external fixation was not published until Hoffmann’s work in 1938 [5]. By the mid-1900s, external fixation had become widely used for fracture management, and application had expanded to include such nontraumatic uses as arthrodesing procedures. In the early 1950s, Charnley applied the newly described methodology of compression arthrodesis to ankle fusions using an external fixator consisting of Steinmann pins in the talus and tibia in the pin-clamp-rod fashion [6,7]. Various external fixation models have since been used to achieve ankle arthrodesis, such as those of Hoffmann [8], Fischer [9], and Calandruccio [10]. Concurrently with Charnley, a Russian physician named Gavriel Ilizarov began experimentation with a smooth wire circular fixator for use in limb lengthening by way of callus distraction [11]. Since its development and introduction to the western hemisphere in the mid-1980s, Ilizarov’s ring fixator system has been studied extensively and shown to be a superior mechanical construct for stabilizing limb segments [12 – 16]. This newfound form of fixation has radically changed many elements of foot and ankle reconstruction, providing * Corresponding author. E-mail address: [email protected] (J. Fleming). 0891-8422/03/$ – see front matter D 2003, Elsevier Science (USA). All rights reserved. PII: S 0 8 9 1 - 8 4 2 2 ( 0 2 ) 0 0 0 5 4 - X

66

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

a modular device that can accommodate the complex limb deformities while performing multiple tasks. This article summarizes the authors’ experience with compression arthrodesis of the rearfoot and ankle using external fixation.

Capabilities and limitations of external fixation of the rearfoot and ankle External fixation provides several advantages over alternative methods for reconstruction of the hindfoot and ankle joints, including rigid immobilization and significant resistance against bending, shear, and torsional stresses. The Ilizarov ring system is a modular device that can accommodate and simultaneously correct multiplanar deformities. The flexibility of the ring system allows for rings, wires, and hinges to be continually adjusted and modified throughout the postoperative setting for changing treatment strategies or management of complications. These devices allow fixation at a distance from the operative site, which permits wound observation and procedures such as grafts or flaps for soft tissue coverage. With rigid skeletal stabilization, immediate or early weightbearing is possible, preventing ‘cast disease’ or regional osteoporosis that frequently accompanies long-term nonweightbearing often characteristic of internal fixation. In the postoperative setting, continually adjustable compression of the arthrodesis site with the capacity for dynamization provides an optimal environment for bony union. Kenwright and Kershaw found that dynamization accelerated the fracture repair and the overall time to union [17,18]. Circular small wire fixators are advantageous when multiple modes of fixation are indicated in adjoining regions, such as simultaneous arthrodesis and distraction-osteogenesis, lengthening through the proximal tibia while compressing distally at the ankle joint. Most hindfoot and ankle reconstructions are amenable to conventional methods of internal fixation, though the following situations are managed more effectively through use of an external fixator: 1. Limited talar bone stock 2. Osteoporosis 3. Limb-length discrepancy 4. Neuroarthropathy 5. Failed or revisional ankle arthrodesis 6. Infected ankle arthrodesis 7. Failed total ankle arthroplasty 8. Severe deformity 9. Spastic neuromuscular disease 10. Extensive contractures 11. Distraction arthrodiastasis External fixation is indicated in the presence of severe deformities, insufficient bone integrity, or infection that may preclude the use of traditional fixation methods. For example, avascular necrosis of the talus with secondary collapse of

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

67

the talar body results in substantial loss of bone substance, greatly compromising screw placement and thread purchase in an attempt to create rigid fixation in the hindfoot. This distorted architecture can be easily stabilized by multiple small diameter transosseous wires for ankle and subtalar fusions. Similarly, Charcot neuroarthropathy presents significant challenges to the foot and ankle surgeon from two perspectives. The severe midfoot and rearfoot collapse and osseous destruction in combination with regional osteoporosis lends itself to fine wire fixation. Second, cast immobilization and single-limb weightbearing during the postoperative period allows weight transfer to the contralateral limb, possibly inciting a similar breakdown on a healthy foot. Stabilization and compression of a failed infected arthrodesis site or pseudoarthrosis can result in satisfactory fusion and salvage of a functional extremity [19]. External fixation is used at the authors’ institution primarily for compression arthrodesis of hindfoot joints, especially in patients with complex deformity and significant structural abnormalities. Rigid fixation constructs are possible in the distal lower extremity, though with certain drawbacks. Safe corridors for pin and wire placement in this territory are narrow. Transosseous wires have the potential to violate hazardous or unsafe zones and impale myotendinous or neurovascular structures. Accidental joint penetration with half-pins or wires can occur, potentially leading to arthrosis or joint sepsis. As with any form of rigid fixation, stress shielding of bone is inevitable. When external fixation is used for passive mechanical compression across an arthrodesis site, bone demineralization is inevitable and restoration of cortical integrity through gradual weightbearing will be required [20]. Radiographic visualization of the surgical site is often difficult because of interposed hardware, but many external systems have now incorporated carbon-fiber rings to eliminate this problem. Immunocompromise, reflex sympathetic dystrophy, and venous stasis disease are also relative contraindications [21,22]. There is a steep learning curve to this method of fixation, which becomes magnified in consideration of the exceptional anatomy of the foot and ankle and specific biomechanics involved in fixation of this region.

Biomechanics and fixator construct The established principles of circular wire fixators must be understood before construction of the foot and ankle frame because these mechanical parameters greatly influence fixator stability and rigidity (Box 1). Although a complete discussion on the biomechanics of external fixators and wire configurations are beyond the scope of this article, several important principles are mentioned to guide the construction of a stable, rigid frame. The foot and ankle are divided into segments or fixation blocks, consisting of a midshaft and distal tibia, talus, and foot segment. In circular fixator systems at least one ring will stabilize each segment. If the fixation segment is greater than 5 cm in length, a double-ring block construct is generally indicated. This arrangement is used in the tibia to counter the effect of the long tibial lever

68

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Box 1. Factors affecting frame stability [24]

Factors that increase stability Wires: number, orientation, tension, diameter Crossing angle wires Diameter and crossing angle of half-pins Centralization of the apparatus Rigidity of materials of rings Number of rings Rigidity of the connection between the rings Surface area of bone end contact Diameter and maturation of the regenerate Factors that decrease stability Increased diameter of rings Length of connection between the rings Length of the regenerate Length of the treated segment

arm. Single-ring fixation blocks are used at the talus and foot level. Alterations in this basic frame setup will depend on the specific goals of the operation and the fixation mode desired between each block. Two half-rings are selected that are 2 to 3 cm larger than the maximal limb girth. Approximately two fingerbreadths distance from the ring to the skin surface is required posteriorly and one fingerbreadth anteriorly. Additional space is needed posteriorly in the leg to accommodate for the increased soft tissue edema postoperatively and requires the frame to be slightly offset in this direction. Eccentrically positioning the bone within the frame has also been shown to increase axial and torsional frame stiffness [13,16]. Inferiorly, the distance from the weightbearing surface of the plantar foot to the foot plate should be approximately two fingerbreadths to allow for postoperative ambulation. The forefoot half ring should provide enough clearance for unobstructed dorsiflexion of the digits. Too little space between the fixator and the soft tissue may result in impingement and ulceration, whereas too much space will decrease the stiffness and compromise the stability of the fixator. Rings are available in sizes from 80 to 240 mm, and most adults require 150 to 160 mm rings for the tibia. These are assembled into two coplanar rings that are placed in the distal tibial segment approximately 8 to 10 cm apart. Longitudinal connecting elements (threaded or telescoping rods) are spaced to provide access to sites on the frame where half-pins and wires will be affixed the frame. This is generally from 2 o’clock to 5 o’clock position laterally and from 7 o’clock to 11 o’clock position medially for a right limb. Four connecting elements will

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

69

connect the rings, and three will connect the distal ring to the foot plate below. The two connected rings comprise the supramalleolar tibial ring block. These rings are attached to a frontal plane foot plate, which may be ‘‘closed’’ with the addition of a transverse plane half-ring distally to resist frame deformation with wire tensioning. The half-ring is also affixed to the inferior tibial ring through a post-and-rod assembly. As the tibial ring block is important in stabilizing the proximal tibial lever arm, so is the foot plate important in stabilizing the distal lever arm (foot) in an attempt to create sagittal plane stiffness and neutralize bending moments at the ankle level. The tibial rings will be secured with at least two transosseous smooth or olive wires each and possibly additional half-pins, which will enter the medial face of the tibia. Efforts should be made to make space in this region of the frame assembly for attachment of half-pins. Likewise, the foot plate will be secured with two oblique crossing smooth or olive wires through the posterior calcaneus. Midfoot and metatarsal wires are accommodated by distal holes on the foot plate (Fig. 1).

General wire considerations Wire placement To prevent damage to neurovascular elements and myotendinous structures with the insertion of wires and pins, a three-dimensional understanding of crosssectional anatomy is essential (Figs. 2, 3). There are many publications that detail this regional anatomy [23,24]. Although a 90° orientation or delta configuration between the wires creates the most stable construct, this is not always possible because of limb anatomy. Fleming et al [13] demonstrated a decrease in the bending stiffness of the frame by a factor of two by decreasing the angulation between two wires from 90 to 45°. Counterposed or ‘‘dueling’’ olive wires are used to fixate the osseous segment in space, creating a sandwich or vice effect when the wire orientation is less than 90°. Additionally, 5-mm or 6-mm half-pins can be placed in the medial face of the tibia to increase resistance to anterior-posterior bending forces acting on the tibia [21]. Olive wires should be used wherever possible because they have been shown to increase bending, torsional, and axial stiffness relative to smooth wires [13]. Consideration should be given to increasing the number of wires in the obese patient or in the presence of osteopenic bone. Half-pins may be used if additional stability is needed because of the narrow safe corridors present and dense cortical architecture of the anterior tibia. Half-pins do not traverse a muscle compartment and are therefore less painful than a transosseous wire, which may facilitate early weightbearing. Two half-pins are required to simulate the stiffness of a single tensioned wire [25]. If olive wires are not used, half-pins will provide resistance to sliding of the osseous segment on smooth tensioned wires.

70

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fig. 1. Basic Ilizarov frame construct for ankle and hindfoot reconstruction. Two transverse coplanar rings stabilize the distal tibia, and a ‘‘closed’’ foot plate is used to stabilize the hindfoot and midfoot regions. Counterposed or ‘‘dueling’’ olive wires and half-pins stabilize bony segments. An additional ring may be added at the level of the talus for an isolated tibiotalar fusion.

Wire tensioning The functionality of the smooth wire external fixator depends on tensioned transosseous wires. Placing the wires under tension provides the stability necessary to achieve axial compression and the mechanical resistance to eliminate distractive forces. The appropriate wire tensions for the foot and leg are listed in Box 2. There are several techniques for tensioning smooth wires, including the Russian slotted bolt head torque and turnbuckle techniques, the post tilt technique, and the Italian dynamometric wire tensioner technique, each with specific advantages and disadvantages. The Russian slotted bolt head torque consists of rotating the bolt head and nut simultaneously against a wire fixed to the contralateral side of the frame (Fig. 4B). This technique may add 10 to 20 kg of tension and can be done in

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

71

Fig. 2. Cross-sectional anatomy for transosseous wire/pin placement in the leg. (A) Mid-leg. Crosssection just distal to the midpoint between the knee and ankle joints. The posterior neurovascular (NV) bundle lies at the geometric center of the leg and the anterior NV bundle lies on the anterior surface of the interosseous membrane. The subcutaneous border provides 140° safe corridor for wire/pin insertion. Transverse and medial face wires combined with a 5-mm or 6-mm half-pin provide stability at this level. (B) Distal leg. This section is approximately 10 to 12 cm proximal to the level of the ankle joint. The anterior NV bundle begins to move anteriorly between the extensor hallucis longus (EHL) and tibialis anterior (TA) muscle bellies; the posterior NV bundle runs posterior to the interosseous membrane in the deep posterior compartment. The safe corridor decrease at this level to 120°. A similar wire/pin configuration is seen. Half-pins may be readily used at A and B levels because of the high percentage of cortical bone present in the tibia. (C) Ankle. Cross-section just proximal to the level of the ankle joint. If the fibula is intact, it may be stabilized by a lateral oblique wire directed from posterolateral to anteromedial. Remaining wires are directed from medial to lateral. The major NV bundle is located in the posteromedial quadrant.

the office. The turnbuckle used in the original Russian system is affixed to the wire and tensioned against the frame. The post tilt technique involves tightening a post tilted toward the limb with its affixed smooth wire straight, thus straightening the post and increasing tension on the wire. Manual wire tensioning with the torqued slotted bolt or turnbuckle methods should be avoided in the foot and leg because it leads to inconsistent wire tensions and precludes the use of these modalities in the

72

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fig. 3. Cross-sectional anatomy for transosseous wire/pin placement in the foot. (D) Hindfoot. Axial section through the proximal hindfoot demonstrating location of anterior and posterior neurovascular structures. The anterior structures traverse the ankle joint between the extensor hallucis longus (EHL) and tibialis anterior (TA) tendons. The posterior bundle enters the foot just posterior and inferior to the medial malleolus in the third compartment of the tarsal tunnel and courses distally into the plantar vault. (E) Hindfoot. Calcaneus is stabilized by two counterposed crossing olive wires at approximately 90° to each other. These wires stabilize the hindfoot to the foot plate. Although half-pins may be used in the same orientation, the cancellous architecture of the calcaneus may be better suited for fine wire fixation. (F, G) Midfoot/forefoot. Sections through the metatarsal bases and metatarsal shafts respectively. Just distal to the Lisfranc articulation, dorsally directed oblique crossed wires may be used to stabilize this region. Small diameter threaded half-pins may be placed in the first metatarsal base. The distal forefoot is similarly stabilized with a combination of dorsally directed crossed wires and pins with care taken to avoid the dorsal NV structures.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

73

Box 2. Approximate wire tensions in the foot and leg [26]

Half-rings/drop wires: 50 kg Pediatric patients (1.5 mm): 100 –110 kg Adults patients (1.8 mm): 120 –130 kg Foot: 70 –80 kg Increase wire size, wire tension, and number of wires with increasing body weight.

postoperative setting. The Italian originated dynamometric wire tensioner is a device with turnbuckle resemblance that is calibrated between 50 and 130 kg and can be dialed to deliver the appropriate amount of tension (Fig. 4A). This device can consistently achieve the greatest wire tensions, although caution should be used when tensioning against the softer cancellous bones of the foot. Counterposed olive wires should be tensioned simultaneously in the foot and leg to prevent shifting of the osseous segments. Wire insertion techniques Wire penetration should always occur within the safe corridor on the opposite side of the limb away from the neurovascular structures or the structure at risk (SAR). As the wire passes the far cortex, a mallet is used to advance the wire

Fig. 4. Wire tensioning techniques. (A) The Italian dynamometric wire tensioner. The wire tensioner device is calibrated between 50 and 130 kg and can be dialed to deliver the appropriate amount of tension. This device consistently achieves the greatest wire tensions, although caution should be used when tensioning against the softer cancellous bones of the foot. ‘‘Dueling’’ olive wires should be tensioned simultaneously in the foot and leg to prevent shifting of the osseous segments. (B) Russian tensioning technique. Torqued slotted bolt head, 10 mm hexagonal slotted bolt attached to frame, friction fit to smooth wire. Nut affixed to bolt from opposite side of ring. Opposing wrenches turn the secured nut-bolt-wire assembly away from the bone segment after the opposite wire end is fastened to the frame. This torque movement of the bolt head creates wire tension.

74

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

through the myofascial compartment; continued drilling may engage the neurovascular bundle, ‘‘wrapping’’ it around the wire. Sterile pin loosening and loss of stability resulting from thermal bone necrosis can be prevented by intermittent start-stop drilling at low speeds using the sharper bayonet tips at all times. A moistened sponge or irrigation may also be helpful during wire insertion to reduce temperatures at the wire/pin interface. Any wire that is a significant distance from the ring and requires multiple stacked washers or a component greater than a single hole post should be replaced as wire stiffness decreases with increasing distance from the ring. ‘‘Drop’’ wires should be avoided as a third point of fixation because they cannot be appropriately tensioned without frame deformation. Reduced wire tension leads to instability and motion at the wire/ bone interface, producing osteolysis and higher infection rates secondary to soft tissue irritation [24]. Any skin tension around the wires should be released to prevent soft tissue irritation and discomfort.

Tibiotalar arthrodesis Literature review/indications Despite recent developments in the treatment of ankle arthritis, such as total ankle arthroplasty, ankle arthrodesis remains the gold standard for end-stage ankle arthrosis. Continuing advancements in osteoarthritits, such as arthroscopy, viscosupplementation, arthrodiastasis, and realignment osteotomies, have improved clinical outcomes and deferred the time to fusion. Hammerschlag achieved 100% union in a series of 10 ankle fusions using anterior arthrotomy and a small wire fixator with a single supramalleolar and talar ring [27]. Two wires were placed in the talus and all patients were allowed to weightbear postoperatively without forefoot stabilization from the fixator. Hammerschlag’s indications included osteopenia from chronic inflammatory disease, septic arthritis, neuromuscular disease, and severe deformity or posttraumatic deformities. Hawkins et al also described good success in 17 patients with the Ilizarov technique for ankle fusion in patients with complex distal tibial pathology or failed arthrodesis [28]. They reported an 80% union rate with a 22-month follow-up. Approximately 50% of their patients underwent concomitant leg lengthening for segmental bone defects, which likely accounts for their high rate of complication and increased time in the fixator. Laughlin and Calhoun also reported successful ankle arthrodesis in 16 of 20 patients with small wire fixators [29]. Fusion was combined with concomitant tibial lengthening for segmental bone loss in 12 patients. Kenzora et al [8], Kitaoka et al [30], and Rothhacker et al [9] all reported similar fusion rates employing biplanar pin fixators for revisional arthrodeses and fusion secondary to posttraumatic conditions. Each study used comparable frame constructs and pin placement with multiple transverse tibial pins and two transverse talar pins. Kenzora et al found substantially dissimilar failure rates for patients who experienced high-energy or

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

75

low-energy injuries. The energy level of the injury was defined by the degree of bony comminution, the presence of joint dislocation, and the condition of the soft tissue envelope at the time of injury. High-energyy and low-energy groups achieved 69% and 100% primary union respectively. They also reported a 43% prevalence of pin tract infections, which may be secondary to the large diameter pins characteristic of these devices. Perioperative considerations The patient is positioned in the lateral decubitis position with the affected extremity up. If a radiolucent operating table is available, the contralateral extremity may be flexed at the hip and knee and safely secured to the border of the table to facilitate intraoperative fluoroscopy. A pneumatic thigh tourniquet is used to facilitate visualization during dissection and joint resection. The patient should not be fully paralyzed after intubation so that wires that penetrate or contact nerve structures during insertion will produce a muscular reaction and possible nerve damage may be avoided. A transfibular approach is the most commonly employed approach at the authors’ institution when external fixation is chosen. The fibula may also be left intact. Regardless of the fixation method used or the incisional technique chosen, ankle arthrodesis must strictly adhere to Glissan’s [31] four requirements to achieve solid bony union: (1) complete removal of all cartilage, fibrous tissue, and any other material that may prevent contact of raw bone surfaces; (2) accurate and close fitting of the fusion surfaces; (3) optimal position of the ankle joint; and (4) maintenance of the bone apposition in an undisturbed fashion until the fusion is complete. As with any joint arthrodesis, the position of fusion will ultimately dictate the outcome and long-term functional capabilities, and largely relies on minimizing stress transfer to adjacent joints. This is most critical in the ankle joint because of its implications on the ascending skeletal mechanics of the knee and hip articulations in addition to the subtalar and midfoot joints. The optimum position of fusion of the ankle is neutral flexion, slight hindfoot valgus (0– 5°), and approximately 5 to 10° of external rotation or rotation, which mimics a nonpathologic contralateral limb [32]. Posterior displacement of the talus beneath the tibia creates a shorter lever arm and decreased stresses at the knee level. This is of primary importance in Charcot reconstructions as the shorter lever arm minimizes bending forces across the midfoot, which may potentially reactivate a neurotrophic breakdown. Incisional approach/exposure The modified transfibular approach, originally described by Adams [33], is performed through two incisions. The lateral incision begins over the lateral aspect of the fibula at the distal third of the leg. It courses distally over the fibula to the level of the sinus tarsi. Dissection is carried down to the level of the periosteum overlying the fibula. The cutaneous portion of the superficial peroneal nerve exits the crural fascia at variable levels and must be anticipated in the

76

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

dissection and protected. The distal fibula is osteotomized in a beveled fashion approximately 2 cm above the level of the ankle joint and freed from its soft tissue envelope. Proximal fibular resection may create instability of the distal fibular segment. Care should be taken not to violate the perforating peroneal artery thsy penetrates the interosseous membrane directly superior to the distal syndesmotic complex. The fibula may be denuded of any remaining soft tissues and morcillized in a bone mill to augment any remaining defects or may be used as an onlay graft described below. Subperiosteal dissection is then carried across the anterior tibia for greater exposure to the anterior ankle joint. After returning the patient to the supine position, a medial incision is created beginning several centimeters above the level of the plafond coursing over the medial tibiotalar articulation and continuing distally to the level of the talonavicular joint. Anatomic dissection is carried down to the anterior ankle capsule with care taken to preserve the saphenous vein and nerve, which are routinely encountered. A longitudinal periosteal/capsular incision is created and the two incisions are communicated subperiosteally for complete visualization of the tibiotalar joint. More extensive dissection is necessary with the use of internal fixation devices relative to circular or monorail external fixators because of the proximal entry point of the usual crossed screw methods. This is crucial in patients who have previously had high-energy injuries of the distal tibial or talus with devascularized articular fragments resulting from periosteal degloving or surgical reconstruction with extensive violation of the periarticular soft tissue envelope. Joint preparation Before joint resection, all loose osteochondral fragments, periarticular ossicles, and exuberant synovitis should be excised to enhance visualization and allow for a greater appreciation of the joint anatomy and borders. Joint surfaces may be prepared by either planal resection or curettage and decortication. The authors prefer to reserve planal resection for severe multiplanar deformities that require significant repositioning and realignment. Curettage and decortication is performed using large curettes to remove the cartilage from the opposing surfaces of the tibial plafond and talar dome, including the medial talar facet and its corresponding articulation on the tibia. Curettage and decortication allows for minor angular adjustments while maintaining the ‘‘anatomic’’ concave-convex contours. This construct affords greater rotational stability and allows for continual intraoperative repositioning and adjustment. This technique also maximizes limb length in patients who may already have preexisting limb-length discrepancies secondary to posttraumatic conditions. For greater visualization of the joint, a lamina spreader may be sequentially placed in the anterior and posterior joint margins to facilitate visualization preparation of the fusion sites. If a half-pin fixator is chosen as the primary form of fixation, then the fixator may be applied before the dissection and used for joint distraction purposes before final reduction and compression of the arthrodesis.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

77

When saw resection is used from the lateral approach, an osteotome or malleable retractor may be inserted through the medial incision between the talus and the medial malleolus to prevent inadvertent transection of the medial malleolus. Care is taken to preserve the medial malleolus and the adjacent deltoid ligament for several reasons. First and foremost, the deltoid artery (a branch off the posterior tibial or medial plantar arteries) penetrates the deltoid ligament and supplies the medial third of the talar body [34]. This is a significant blood supply that must be maintained to maximize surgical success in an already compromised region. The medial malleolus also provides increased contact area for the fusion mass and rotational stability. Last, as Paley [35] illustrates, resection of the medial malleolus encourages alignment of the cortical borders of the tibia and talus, which essentially translates the foot laterally from beneath the weightbearing vector of the tibia creating strain and stress on the medial hindfoot and midfoot structures. The posterior tibial tendon and the posterior neurovascular bundle are placed at a considerable risk with this technique. Before final positioning and provisional fixation, all fusion surfaces must be inspected to insure that raw cancellous bleeding surfaces have been achieved. Perforation of the subchondral plate on either the tibia or the talus will not suffice for this procedure, as both joint surfaces must be completely decorticated with pinpoint bleeding. Ilizarov technique for tibiotalar arthrodesis Frame construct The subtalar joint may be preserved in those patients who possess supple joint motion without coexisting pathology. Joint preservation allows for greater compensatory motion postfusion and can be accomplished by the addition of a transverse plane ring at the level of the talus (Fig. 5). The talus is transfixed to the ring by counterposed olive wires, effectively suspending it relative to the calcaneus. This permits isolated compression at the tibiotalar joint level. Compression occurs between the tibial ring block and the talar ring/foot plate with preservation of the subtalar complex (Fig. 6). Alternatively, two wires may be posted from the foot plate transfixing the talar body to create a ‘‘virtual ring’’ [22]. This may be another effective method of preventing compression and arthrofibrosis at the level of the subtalar joint (Fig. 7). Following dissection and joint resection, the arthrodesis site is then reduced, positioned, and temporarily fixated with a 5/6400 Steinmann pin in a retrograde fashion through the heel. The pin may be inserted through the heel pad to the lateral side of the calcaneus and ‘‘walked’’ medially on the plantar cortex to dislodge the plantar lateral neurovascular bundle and avoid injuring this structure [36]. The alignment of the fusion is critical and is continually reassessed. The relationship of the tibial tubercle to the second digit on the contralateral limb should be noted during the preoperative evaluation and symmetrical rotation should be achieved intraoperatively. Overall position and apposition of the arthrodesis should be confirmed clinically and with an image intensifier. Any

78

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fig. 5. Tibiotalar arthrodesis. A 55-year-old man with posttraumatic ankle deformity requiring subsequent ankle fusion. (A, B) Anteroposterior and lateral radiographs depicting varus malalignment and arthrosis of the ankle joint. (C) Postoperative lateral radiograph demonstrating Ilizarov technique for an isolated ankle arthrodesis. The talus is suspended and the subtalar joint is well preserved by the addition of a transverse plane talar ring. Compression is achieved between the talar ring and the tibial ring block. (D) Ilizarov frame for ankle arthrodesis.

defects may be filled with the autogenous bone to maximize contact of the fusion surfaces. The tourniquet is released and the wounds are closed in layers over drains. If the fibula is to be used as an onlay graft, it should be debulked and applied with the decorticated surfaces against the talus and tibia. This may be secured to the tibia with cannulated 4.0-mm screws. Fixation to the talus and tibia will block compression following application of the frame.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

79

Fig. 6. Compression arthrodesis constructs. (A) Ankle arthrodesis. Fixation blocks consist of a tibial segment (proximal two rings) and a rearfoot block (distal two rings). The talus and calcaneus are compressed proximally as a unit to avoid subtalar joint compression. Separate threaded rod assemblies join the central two rings to effect compression at the ankle joint. Note the foot plate above the weightbearing plane of the foot. (B) Pantalar arthrodesis. The tibial fixation block and the foot plate neutralize forces across the leg and foot lever arms, respectively, while compression occurs simultaneously between these segments across the ankle and subtalar joints. (C) Subtalar arthrodesis. This is a variant of the frame assembly shown in (A). The tibial ring block is used and again is attached to the foot plate; however, compression is achieved through an arched wire technique across the subtalar joint posted off of the foot plate. This compresses the subtalar joint while maintaining position of the ankle joint. The posted wire replaces the talar ring in the ankle fusion assembly.

Frame application The preassembled frame should be placed over the limb and any final adjustments made. The first two wires are the most critical to align the long axes of the foot and leg with the fixator. The mounting sequence of the transfixion wires is outlined as follows: 1. Proximal reference wire (a) Proximal ring in tibial ring block at distal one half or two thirds of leg (b) Transverse olive wire from medial to lateral (c) Parallel to ankle joint 2. Distal reference wire (a) Foot plate, midfoot (cuboid) (b) Transverse olive wire lateral to medial 3. Proximal ring, tibial ring block (a) Medial face olive wire (b) Simultaneous tensioning of dueling olive wires in proximal ring 4. Calcaneal wires (a) Two oblique opposing olive wires from proximal to distal from the postero-inferior heel (b) Care taken to avoid the neurovascular bundle medially 5. Inferior ring of tibial ring block (a) Transverse and medial face dueling olive wires (b) Tensioned simultaneously

80

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fig. 7. Tibiotalar arthrodesis with ‘‘virtual talar ring.’’ A 63-year-old woman with complaint of pain and disability for 15 years following an untreated ankle fracture. (A,B) Preoperative anteroposterior (AP) and radiographs depicting significant arthritic change and varus deformity of the ankle joint. There is adaptation and widening of the talar dome and tibial plafond with complete obliteration of the joint space. (C) Postoperative AP radiograph showing reduction of varus alignment and good bony apposition of the arthrodesis site. Note the fibular onlay graft secured to the tibia with screw fixation. (D) Clinical appearance of the ankle and external fixator on the second postoperative day. Again, offset sagittal plane half-pins have been placed into the medial face of the tibia achieving three points of fixation per ring.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

81

Fig. 8. Tibiotalocalcaneal fusion. A 36-year-old man presents with distal tibial pathology resulting from a high-energy pilon fracture secondary to a fall from a 30-foot height during a suicide attempt. Secondary involvement of the subtalar joint required combined tibiotalar and talocalaneal fusions. (A,B) Anteroposterior (AP) and lateral radiographs. Status post-ORIF with valgus and procurvatum deformity and severe end-stage ankle arthrosis. (C,D) Postoperative anteroposterior and lateral radiographs demonstrating ankle and subtalar arthrodesis with Ilizarov technique. An EBI spinal stimulator has been used to enhance fusion. High-energy injuries increase the potential for nonunion because of the periosteal degloving and bony devascularization associated with these fractures. Note the wire deformation at the foot plate level and the associated ‘‘pin drag.’’ Two offset 6-mm half-pins have been added to increase frame stiffness.

82

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

6. Talar ring (a) Opposing olive wires in anterior and posterior talar body 7. Foot plate (a) Opposing olive forefoot wire from medial to lateral (b) Forefoot, midfoot wires are important to eliminate the lever arm acting against the ankle, which may create sagittal plane ‘‘rocking’’ 8. Talar ring (virtual ring, not necessary with talar ring application) (a) Two wires in talus (b) Ring or drop wire off posts 9. Additional half-pins or wires as needed

Fig. 9. Tibiotalocalcaneal fusion. Severe fixed equinovarus deformity resulting from delayed recognition of a compartment syndrome secondary to a gunshot wound. A pantalar fusion was required to attain a rectus foot and ankle. (A,B) Fixed equinovarus deformity. Lateral radiograph demonstrating severe cavus deformity with fixed ankle plantarflexion. (C) Anteroposterior (AP) radiograph demonstrating moderate arthritic change along the lateral column and proximal midfoot with healed stress fractures from altered distribution of weightbearing forces. Long-standing adaptive changes will require repositional midfoot arthrodesis to achieve a plantigrade foot. (D) Oblique postoperative ankle radiograph of a pan talar arthrodesis. A 7.3-mm cannulated screw provides supplemental fixation of the subtalar complex. The ankle fusion is well reduced and compressed with a fibular onlay graft acting as a lateral buttress. (E) Postoperative AP clinical photograph demonstrating weightbearing in Encore fixator with Dynasplint device.mbf

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fig. 9 (continued).

83

84

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fluoroscopic confirmation of pin and wire placement is performed, and the ankle may be compressed by shortening the distance on the threaded rods between the tibial ring block and talar ring or foot plate. The limb and fixator are then rotated under image intensification to assess apposition and overall alignment of the arthrodesis site. The provisional fixation may now be removed and all components must be tightened to ‘‘white-knuckle’’ tightness. Before the dressing application, the frame should be manually stressed in all planes to verify stability. Additional wires or rods may be added as needed to stiffen the overall construct. Variations in this frame may be used to accomplish additional fusions in the hindfoot such as tibiotalocalcaneal arthrodesis (Figs. 8, 9). Half-pin fixator Half-pin uniplanar/biplanar devices have gained popularity because of their relative ease of application and simplicity compared with circular wire fixators (Fig. 10). EBI1, Parsippany, NJ and Orthofix1, McKinney, TX have developed

Fig. 10. Oblique and posterior photographs (A,B) of the EBI Dynafix1 unilateral half-pin fixator technique for ankle arthrodesis. Pins are placed in the posterior talar body and talar neck employing the ankle T-clamp.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

85

Box 3. Instrument sequence for EBI Dynafix1 half-pin external fixator [26]

Talar pin insertion sequence 0.062 (1.6-mm) Kirschner wire 3.2-mm drill 6/5-mm cancellous pins Tibial pin insertion sequence 4.8-mm drill 6/5-mm cortical pins (bicortical) The diameter of the pins should not exceed one third of the diameter of the bone.

comparable half-pin uniplanar monorail devices that may be modified for tibiotalar arthrodesis with the use of a T-clamp for talar pin placement. The EBI Dynafix1 device consists of a central fixator body with a telescoping arm capable of 5 cm of compression/distraction. Joint preparation is performed as previously described, and a 0.06200 Kirschner wire is used as a guide pin for the insertion of the talar neck half-pin. This pin is placed approximately one finger breadth anterior and distal to the medial malleolus and must be inserted in the same plane as the ankle joint to avoid varus or valgus angulation with compression. Wire placement is assessed under image intensifier, and the appropriate sequence for cancellous pin insertion is carried out (Box 3). The T-clamp is then used as a guide for the second pin in the posterior talar body. A small incision is required for placement of the posterior pin between the posterior tibial and flexor digitorum longus tendons. Dissection is carried down to the medial talus and a drill sleeve is inserted to protect the adjacent tendon sheaths. The insertion sequence is repeated ensuring that both pins lie in the same plane parallel to the ankle joint. The body of the fixator may now be aligned with the long axis of the leg and secured to the medial face of the tibia with cortical pins. This requires a 4.8-mm predrill because of the dense tibial cortex. The fixator body is used as a template for proximal pin insertion. The clamp cover locking bolts should be secured with at least 3 cm of clearance between the skin and fixator to accommodate for soft tissue edema [37]. Translational, rotational, and angular fittings should be adjusted and tightened, and the tibiotalar articulation may be compressed under direct visualization. Any defects at the fusion site may then be addressed and the wounds closed over drains. Unlike circular fixators, these surgical sites may be covered with a Jones compression dressing to reduce postoperative edema during the initial stages.

86

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

The fixator may be applied before the surgical dissection and used to distract the ankle joint to aid in joint preparation. If this is anticipated, the compression/ distraction module should be maintained at the midway point, which allows 2.5 cm of compression/distraction.

Tibiocalcaneal arthrodesis Tibiocalcaneal arthrodesis is often necessary when there is destruction of the talus resulting from neuroarthropathy, avascular necrosis, infection, or severe deformity (Figs. 11, 12). Talectomy or loss of talar body height in combination with preparation of the fusion sites on the tibia and calcaneus often leads to a 4-cm loss of limb length [21]. As a result, many surgeons prefer to combine these fusion sites with a proximal tibial lengthening and simultaneous compression at the ankle level using the Ilizarov technique [21,28]. Exposure is accomplished through a lateral hockey stick-type incision over the fibula proximally and extending to the level of the cuboid distally. If the talar body is to be extracted, a transverse incision centered approximately 3 to 5 cm above the tip of the lateral malleolus may be employed to ensure adequate closure without wound ‘‘puckering’’ from resultant limb shortening [21]. If the fibula exists, it is excised and morcelized in a bone mill to augment any defects at the fusion site. The remaining portions of the talar body are then removed, and the area should be debrided of all fibroligamentous tissues and loose bodies to allow flush contact between the tibia and calcaneus. If the talar head and neck are viable, they may be left intact to avoid harvesting additional graft. Planal resection is now performed on the tibial plateau and dorsal calcaneal surfaces. Resection may be aided by the insertion of two orthogonal guide wires in the distal tibia perpendicular to the long axis of the tibia. Additional wires may be inserted into the calcaneus parallel to the sole of the foot. Saw cuts may now be made parallel to these wires to ensure congruous fusion surfaces [21]. The lateral surface of the medial malleolus may also be decorticated to allow fusion, or the entire malleolus may be resected if it hinders reduction of the primary fusion site. The anterior surface of the distal tibia and talar neck may be prepared in a similar fashion. In prior sites of infection, a ‘‘slurry’’ of fresh-frozen irradiated cancellous chips, autologous platelet gel, and vancomycin/tobramycin powder may be used to optimize surgical results. Iliac crest bone grafts may be harvested as needed but should be avoided if possible to decrease postoperative morbidity. Provisional fixation is achieved in a likewise fashion to the tibiotalar arthrodesis, and the wound is closed in layers over a drain. If concomitant leg lengthening is performed, a retrograde nail may be inserted through the arthrodesis site to the proximal tibial metaphysis and locked distally into the tibia and calcaneus. A proximal tibial corticotomy is then performed and the Ilizarov device is applied spanning the corticotomy and arthrodesis sites for the distraction phase. When the desired length is achieved, the nail may be locked proximally and the fixator removed for the consolidation phase, thus reducing the time in the fixator [38]. Proximal lengthening without associated intramedullary

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

87

Fig. 11. Tibiocalcaneal arthrodesis. Tibiocalcaneal fusion Ilizarov technique with concomitant medial and lateral column stabilizations in a 48-year-old noninsulin diabetic who had deformity and chronic ulcerations 1 year before presentation. (A) Preoperative anteroposterior (AP) weightbearing photograph showing Charcot breakdown with secondary varus deformity of the hindfoot and increased load bearing along the lateral forefoot. (B) Charcot neuroarthropathy involving the subtalar and ankle joints with dissolution of the talar body. (C) Lateral radiograph of tibiocalcalneal fusion and ‘‘nailing’’ of the medial and lateral columns with large cannulated screws. Iliac crest grafts were needed to supplement fusion at the tibiocalcaneal and tibionavicular regions. (D) Lateral photograph of Encore fixator for tibiocalcaneal fusion.

88

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

Fig. 12. Tibiocalcaneal arthrodesis using a Taylor spatial frame. A 45-year-old woman with a history of spina bifida and the secondary development neuropathic osteoarthopathy of the ankle and hindfoot requiring tibiotalocalcaneal arthrodesis. (A) Preoperative weigthbearing photograph. Note the severe rotary deformity of the foot and leg. Patient underwent a symes amputation on the contralateral limb from previous complications related to her medical condition. (B,C) Anteroposterior and lateral weightbearing radiograph demonstrating complete collapse with tibiofibular diastasis and ankle valgus. There is also significant subtalar and midtarsal joint involvement with the development of a ‘‘rockerbottom’’ deformity. (D) Axial CT through the posterior ankle and hindfoot articulations. Endstage arthrosis at the ankle and subtalar levels. (E) Postoperative photograph of tibiotalocalcaneal arthrodesis using a Taylor Spatial Frame. Restoration of the rotary alignment and frontal plane hindfoot position.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

89

Fig. 12 (continued).

nailing will significantly increase the treatment period in the fixator as the consolidation phase is generally twice the time required for the lengthening alone. Frame construct and application The basic rearfoot fixator construct is used. Wire placement is identical to that of the tibiotalar arthrodesis with the exception of the talar ring. Alternatively, the anterior tibial and talar neck segments may be stabilized by the arched wire technique, which will be discussed later. Intraoperative compression between the foot plate and proximal ring block is observed under image intensification and the frame is manually stressed with additional components added as needed for stiffness in all planes.

Triple arthrodesis Conditions such as rheumatoid arthritis or posttraumatic deformitites such as calcaneal fractures require triple arthrodesis to relieve pain and create stability in the hindfoot. This procedure is performed through a two-incisional approach. The medial incision between the tibialis posterior and tibialis anterior tendons provides access to the talonavicular joint; the lateral incision is placed superior to the peroneal tendons overlying the floor of the sinus tarsi. Planal saw resection or minimal resection techniques may be employed with care taken to respect the blood supply to the talus, especially the vessels penetrating the dorsal neck

90

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

region. Following removal of the articular cartilage, temporary fixation with 5/6400 Steinmann pins is employed. Several relationships must be observed, including the position of the lateral talar process and congruency of the posterior subtalar joint facet, talar coverage, the position of the calcaneus to leg, and forefoot to rearfoot relationship. The ideal alignment of the arthrodesis is slight hindfoot valgus (3 –5°), talonavicular congruity, and a valgus attitude of the forefoot to rearfoot. Failure to accomplish the latter will result in compensatory pronation through the ankle joint postoperatively with resulting deltoid failure and valgus deformity of the mortise. The Steinmann pins are then bent and locked into the adjacent cortices, and the wounds closed in layers over drains. The preconstructed frame, consisting of one or two tibial rings and a foot plate, is stabilized to the tibia and calcaneus using the standard mounting sequence. Under fluoscopic guidance, a 1.8-mm smooth wire is placed through the talar neck/body and arched or bent backward to create a perpendicular relationship between the posterior facet and the vector of wire pull [39]. Either ends of the wire are then stabilized to the foot plate and tensioned. This ‘‘arched wire’’ compression technique is illustrated in Fig. 13. A similar method is employed for arthrodesis of the midtarsal region (Fig. 14). Additional wires are added as needed. In ankle and tibiocalcaneal applications, compression is achieved in a ring-toring fashion or decreasing the distance between foot and leg rings. Triple arthrodesis is unique in that it relies on wire-to-ring compression (‘‘arched wire’’) and may be supplemented with internal fixation (see Fig. 6). This method has a high learning curve and is not recommended for those who have minimal experience with ring fixators.

Distraction arthrodiastasis Joint distraction is the most recent joint-sparing advancement in the treatment of osteoarthritis (OA) and arthrofibrosis in the lower extremity. Van Valburg et al [40,41] demonstrated that Ilizarov joint distraction delays and may obviate the

Fig. 13. ‘‘Arch’’ wire compresssion technique. (A) A transosseous wire placed through the talar body and deflected or ‘‘arched’’ perpendicular to subtalar joint. The wire ends are then affixed to foot plate. (B) Talar wire is then placed under tension which encourages the wire to assume a linear configuration and compress the subtalar joint. This technique may also be used for midfoot fusion.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

91

Fig. 14. Triple arthrodesis. (A) Lateral radiograph of failed adult flatfoot reconstruction with an arthroeresis device. Significant arthritic changes have occurred within the subtalar and talonavicular articulations. (B,C) Postoperative radiographs of a triple arthrodesis demonstrating internal splintage of the talonavicular and calcaneo-cuboid joints with arch wire compression across these segments encouraging fusion. This technique is also employed at the level of the subtalar joint.

need for arthrodesis in patients with severe ankle OA. In a preliminary 2-year follow-up of 11 patients, they reported symptomatic relief and stimulation of articular cartilage repair as evidenced by an increased joint space. Further investigation of the effects of this technique on canine cartilage showed normalization of chondrocyte function and improved changes in cartilage metabolism [42]. At least superficially, this joint preservation technique seems to have some promise and may play a crucial role in the treatment of OA, especially in the younger active patient. Arthrodiastasis may be accomplished through the application of two supramalleolar tibial rings and a foot plate. Telescoping rods are used as longitudinal

92

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

connecting elements to achieve distraction. Smooth wire placement in the foot and leg remains unchanged from the prior techniques. Talar wires are used to prevent concomitant distraction across the subtalar joint. Because this frame is designed for distraction and not compression, fewer transfixion wires may be added as this application gains stability from the increased tension of the intact soft tissue structures of the foot and leg [21]. Recommended tibiotalar distraction is 0.5 mm per day for 5 days, and distraction is maintained for approximately 8 to 12 weeks [40]. Wire tensions should be reassessed following maximum distraction as the wires may loosen with soft tissue relaxation. Patients remain fully weightbearing during the length of treatment. Frame application may be performed in conjunction with ankle arthroplasty, arthroscopy, or realignment ostetotomy. Because of the extensive ligamentous constraints of the medial and lateral collateral ligaments, caution must be used during distraction because ligament rupture and ankle destabilization are possible. Treatment may be enhanced by the off-label use of viscosupplementation (Hyalgan#, Synvisc#).

Complications Complications resulting from external fixators, primarily fine wire ring fixators, may be divided into three categories: major, minor, and permanent [22]. Major complications are those that require operative treatment to resolve and can compromise the final outcome if not addressed appropriately (ie, nonunion at the docking site). Dahl and Valezquez [43,44] noted that major complications decrease with increasing surgeon experience. Minor complications are the most common and may be resolved nonoperatively with little difficulty (ie, simple pin tract infection). Those complications that cannot be alleviated and often preclude the original goals of treatment are termed permanent. These complications may arise intraoperatively, postoperatively, or following removal of the frame. Intraoperative complications are most often related to placement of smooth wires through myofascial compartments with direct injury to neurovascular structures. Complications of this nature are directly proportional to the surgeon’s understanding of cross-sectional anatomy and technique of wire insertion. Wire penetration should begin on the side of the limb away from the SAR (neurovascular bundle), and the wire should be tapped through the myofascial compartment with a mallet to avoid ‘‘wrapping’’ of the neurovascular structures. Vascular lesions occur from direct injury to arterial structures, though these lesions rarely lead to problems because of the small diameter of the wires [22]. In the presence of an acute lesion intraoperatively, the wire is removed and direct pressure is applied to the vessel. Vascular disruption may also arise from a tibial corticotomy or fibular osteotomy/resection. Compartment syndrome can occur postoperatively from vascular penetration, and the affected compartments should be monitored directly with compartment pressure measurements. Passive stretch of the myotendinous structures is generally unreliable in the presence of wires

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

93

within the myofascial compartments. When recognized, compartment syndrome is treated with prophylactic fasciotomy. A sterile doppler may be used after frame placement to ensure arterial flow. Angiography or duplex sonography and surgical exploration of the affected vessel may be required. Pseudoaneurysm and arteriovenous fistulas are also reported complications of iatrogenic vessel penetration, which may require repair. Polak et al [45] reported two cases of pseudoaneursym following iatrogenic vascular insult with small wire fixators, which became symptomatic only after removal of the fixator. Damage to a peripheral nerve may be recognized by significant pain in the distribution of the nerve. On the first postoperative day, each wire is ‘‘strummed’’ or tapped in an attempt to elicit neurologic symptoms. Symptomatic wires require immediate removal, and nerve exploration and decompression is occasionally necessary [46]. Incomplete musculoskeletal paralysis of the patient during general anesthesia will also increase the ability of the surgeon to recognize nerve injury. Common peroneal and posterior tibial nerves should be taken into account when executing acute corrections involving internal and external rotation movements respectively. Peripheral nerves may be monitored during wire insertion to reduce the risk of neurologic sequela [47]. Pin tract infections are usually minor complications encountered in approximately 10% of all wires [24]. These are generally related to inappropriate pin care, loose wires, or increased skin tension around areas of wire penetration. During the postoperative hospitalization course, patients are given intravenous cefazolin until their time of discharge. Antibiotics are prescribed if redness or discharge ensues. Patient education regarding hygiene and pin care protocol is critical. The first dressing change may be performed around 5 to 7 days postoperatively. Pin sites are ‘‘flossed’’ with a dilute solution of Hibiclens1 in normal saline on a sterile 4 by 4 dressing sponge. Bactroban ointment is then applied to the base of the wires, followed by gauze sponges and hexagonal compression sponges to eliminate motion at the wire/skin interface. The wires are maintained in this fashion for 2 weeks, during which showering and swimming in chlorinated pools is permitted. Wires should be assessed during each postoperative visit and retensioned with the slotted bolt head torque Table 1 Dahl’s classification for pin tract complications Grade

Appearance

Treatment

0 1 2 3 4 5

Clear Slightly red Red/tender yellow drainage possible Red/painful/purulent drainage Radiolucency in combination with purulence Sequestrum

NaCl and Bactroban NaCl and Bactroban PO abx with TID pin care Definite PO abx Removal of pin, possible IV abx Removal of pins/debridement of pin tract with intravenous abx

PO, oral; abx, antibiotics; TID, three times daily. Data from Sontich JK. Essentials of Ilizarov. Comprehensive Ilizarov solutions. Atlanta, Georgia, April 29, 2002.

94

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

technique or wire tensioner if possible. Pin tract infections may range from clear serous drainage to osteomyelitis requiring pin removal and surgical debridement. Dahl devised a classification and treatment protocol for pin tract infections (Table 1). Additional complications such as joint contractures or joint luxation, wire or component failure, and difficulties related to limb lengthening (eg, delayed or premature consolidation, poor regenerate formation, and angular deviations) may be encountered during treatment.

Frame removal The appropriate time for frame removal depends on when consolidation of bone or the arthrodesis site occurred radiographically and clinically. The fixator may be removed in piecemeal fashion over several weeks, beginning with wires and threaded rods, to allow gradual axial micromotion on the stress-shielded bones. Delayed bony union may be accelerated by dynamization of the frame through a sequential ‘‘destabilization’’ of the rings and wires. The frame may also be removed as a unit followed by a period of strict nonweightbearing in a short leg cast. Pin and wire sites require local wound care and observation until skin closure occurs. Frame removal is typically performed in the operating room or patient holding area under mild sedation. References [1] Malgaigne JG. Considerations cliniques sur les fractures de la rotule et leur traitement par les griffes. J Connaissance Md Pratiques 1853;16(9). [2] Parkhill C. A new apparatus for the fixation of bone after resection and in fractures with tendency to displacement. Trans Am Surg Assoc 1897;15:251. [3] Lambotte A. Le traitment des fractures. Paris: Masson; 1907. [4] Anderson R. An automatic method for treatment of fractures of the tibia and fibula. Surg Gynecol Obstet 1934;58:639. [5] Hoffmann R. Rotules a os pour la reduction dirigee, non saglante, des fractures (osteotaxis). Helv Med Acta 1938;6:844. [6] Charnley J. Compression arthrodesis of the ankle and shoulder. J Bone Joint Surg Br 1951;33:180 – 91. [7] Charnley J. Compression arthrodesis of the knee. J Bone Joint Surg Br 1948;30:478. [8] Kenzora JE, Simmons SC, Burgess AR, et al. External fixation arthrodesis of the ankle joint following trauma. Foot Ankle Int 1986;7(1):49 – 61. [9] Rothacker GW, Cabanela ME. External fixation for arthrodesis of the foot and ankle. Clin Orthop 1983;180:101 – 8. [10] Williams Jr JE, Marcinko DE, Lazerson A, et al. The Calandruccio triangular compression device: a schematic introduction. J Am Podiatr Assoc 1983;10:536. [11] Ilizarov GA. New principles of osteosynthesis by means of crossing pins and rings. Kurgan, Russia: Internal Publication Book; 1954. [12] Gasser B, Bowman B, Wyder D, et al. Stiffness characteristics of the circular Ilizarov external fixator device as opposed to conventional external fixators. J Biomech Eng 1990;112:15. [13] Fleming B, Paley D, Kristiansen T, et al. A biomechanical analysis of the Ilizarov external fixator. Clin Orthop 1989;241:95.

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

95

[14] Kummer FJ. Biomechanics of the Ilizarov external fixator. Bull Hosp Jt Dis Orthop Inst 1989;49:140. [15] Paley D, Fleming B, Catagni M, et al. Mechanical evaluation of external fixators used in limb lengthening. Clin Orthop 1990;250:50. [16] Podolsky A, Chao E. Biomechanical performance of Ilizarov external fixators. Trans Orthop Res 1990;15:416. [17] Kershaw C, Cunningham J, Kenwright J. Tibial external fixation, weight bearing and fracture movement. Clin Orthop 1993;293:28 – 36. [18] Kenwright J, Goodship A. Controlled mechanical stimulation in the treatment of tibial fractures. Clin Orthop 1989;241:36 – 47. [19] Cierny III G, Cook WG, Mader JT. Ankle arthrodesis in the presence of ongoing sepsis: indications, methods, results. Orthop Clin North Am 1989;20:709. [20] Fischer DA. Skeletal stabilization with a multiplane external fixation device: design rationale and preliminary clinical experience. Clin Orthop 1983;180:50 – 62. [21] Paley D, Herzenberg JE. Applications of external to foot and ankle reconstruction. In: Myerson MS, editor. Foot and ankle disorders. Philadelphia: WB Saunders; 1999. p. 1135 – 88. [22] EBI1. Essentials of Ilizarov and comprehensive Ilizarov solutions. Parsippany, NJ 2002. [23] Behrens F. General theory and principles of external fixation. Clin Orthop 1989;241:15 – 23. [24] Catagni MA. Atlas for the insertion of transosseous wires and half-pins: Ilizarov method. In: Maiocchi AB, editor. Memphis (TN): Smith and Nephew; 2002. [25] Calhoun JH, Li F, Bauford WL, et al. Rigidity of half-pins for the Ilizarov external fixator. Bull Hosp Jt Dis 1992;52(1):21 – 6. [26] EBI. Product brochure. Parsippany, NJ: EBI, 2002. [27] Hammershlag WA. Ankle arthrodesis using a ring external fixator. Tech Orthop 1996; 11(3):263 – 8. [28] Hawkins BJ, Langerman RJ, Anger DM, et al. The Ilizarov technique in ankle fusion. Clin Orthop 1994;303:217 – 24. [29] Laughlin RT, Calhoun JH. Ring fixators for reconstruction of traumatic disorders of the foot and ankle. Orthop Clin North Am 1995;26:287 – 94. [30] Kitaoka HB, Anderson PJ, Morrey BF. Revision of ankle arthrodesis with external fixation for non-union. J Bone Joint Surg Am 1992;74:1191 – 200. [31] Glissan DJ. The indications for inducing fusion at the ankle joint by operation with description of two successful techniques. Aust N Z J Surg 1949;19:64 – 71. [32] Buck P, Morrey BF, Chao EY. The optimum position of the arthrodesis of the ankle: a gait study of the knee and ankle. J Bone Joint Surg Am 1987;69:1052 – 62. [33] Adams JC. Arthrodesis of the ankle joint: experiences with the transfibular approach. J Bone Joint Surg Am 1948;30:506. [34] Peterson L, Goldie I, Lindell D. The arterial supply of the talus. Acta Orthop Scand 1974;45:260 – 70. [35] Paley D. Ankle malalignment. In: Kelikian AS, editor. Operative treatment of the foot and ankle. Stamford (CT): Appleton and Lange; 1999. p. 547 – 86. [36] Pochantko DJ, Smith JW, Philips RA, et al. Anatomic structures at risk: combined subtalar and ankle arthrodesis with a retrograde intramedullary rod. Foot Ankle Int 1995;16:542. [37] Nepola JV. DFS1 Standard Fixator, DFS1 Ankle Clamp, DFS1 T-Clamp: surgical technique. EBI Fracture Management. Product brochure. EBI1, Parsippany, NJ, 2002. [38] Herzenberg JE, Paley D. Tibial lengthening over nails (LON). Tech Orthop 1997;12(4):250 – 9. [39] LaBianco GJ, Rush SM, Vito GR. External fixation. In: Banks AS, Downey MS, Martin DE, Miller SJ, editors. McGlamry’s comprehensive textbook of foot and ankle surgery. 3rd edition. Philadelphia: Lippincott Williams and Wilkins; 2001. p. 107 – 38. [40] Van Valburg AA, van Roermund PM, Lammens J, et al. Joint distraction in the treatment of osteoarthritis: a two-year follow-up of the ankle. Osteoarthritis Cartilage 1999;7:474 – 9. [41] Van Valburg AA, van Roermund PM, Lammens J, et al. Can Ilizarov joint distraction delay the need for an arthrodesis of the ankle? A preliminary report. J Bone Joint Surg Am 1995;77:720 – 5.

96

S. Kalish et al / Clin Podiatr Med Surg 20 (2003) 65–96

[42] Van Valburg AA, van Roermund PM, Marijnissen AC, et al. Joint distraction in the treatment of osteoarthritis (II): effects on cartilage in a canine model. Osteoarthritis Cartilage 2000;8:1 – 8. [43] Dahl MT, Gulli B, Berg T. Complications of limb lengthening, a learning curve. Clin Orthop 1994;301: 10 – 8. [44] Valezquez RJ, et al. Complications of use of the Ilizarov technique in the correction of limb deformities in children. J Bone Joint Surg Am 1993;75:1148 – 56. [45] Polak WG, Pawlowski S, Skora J, et al. Vascular complications after the treatment with Ilizarov external fixators. Vasa 2001;30(2):138 – 40. [46] Slomka R. Complications of ring fixators in the foot and ankle. Clin Orthop 2001;391:115 – 22. [47] Makrov M, Birch JG, Delgado MR, et al. Effects of external fixation and limb lengthening on peripheral nerve function. Clin Orthop 1996;329:310 – 6.