DEFINITION

Talus fractures are high-energy fractures that can have traumatic bone loss, avascular necrosis (AVN), and infected nonunion as the outcome of the injury.1,3,15,23

Acute talar bone loss and subsequent AVN and infection will present a cascade of hindfoot reconstruction problems (FIG 1).

Excision of the talus causes 3 to 4 cm of leg length discrepancy (FIG 2). This defect can be reconstructed with internal fixation and bone grafting to maintain leg length.16

Traumatic loss of the talus or AVN is also treated with tibiocalcaneal arthrodesis using internal fixation without reconstruction of leg length.4,11,14,19

Replacement of the traumatic extrusion of the talus has had a high level of infection in case studies.6,15 In recent case series, there has been success in reimplanting extruded talar body fractures without a high incidence of infection.2,8,20,21

If there is severe comminution of the talus, contamination from extrusion, infection, or a compromised soft tissue envelope, massive bone grafting and internal fixation would have a high risk of failure and

infection. Half-pin fixators with a calcaneal tibial Steinmann pin have had a poor rate of arthrodesis.18 Circular fixation provides an alternative to amputation in these complex cases.5,10,17,22

Because the pins and wires used in circular fixation are not in the zone of injury, a carefully débrided

arthrodesis site can be compressed to achieve arthrodesis without foreign body internal fixation.

 

 

 

FIG 1 • The extent of bone loss and infection will determine the reconstruction. A. Extensive infection of the talar dome compromising tibial talar arthrodesis. B. Complete necrosis of the talar body. C. Necrosis of the entire talus. D. Necrosis of the plafond and talus. E. Traumatic ejection or crushing of the talar body. F. Traumatic ejection or crushing of the talus.

 

 

Wounds can heal by secondary intention over many weeks and the foot can be salvaged.

 

For patients with appropriate physiology, a proximal leg lengthening can be added to the reconstruction to equalize leg length.

 

The reconstructed extremity requires shoe modifications to improve gait.

 

With a well-aligned tibiocalcaneal arthrodesis, the patient may participate in an active life without the problems and expense of a below-knee prosthesis.

 

ANATOMY

 

The talus has precarious blood supply because approximately two-thirds of the surface area is covered by articular cartilage.

 

The ankle articulation, talar navicular joint, and the three facets of the subtalar joint leave limited areas on the neck of the talus and inferior surface for penetration of blood vessels into the dense bone of the talus.

 

The talus has no muscular attachments and is surrounded by the joint capsules of the multiple joints and a thin layer of soft tissue with bypassing tendons, vessels, and nerves.

 

Open fracture-dislocations of the talus are high-energy injuries that cause disruption of the blood supply by dislocation, ejection of fragments, and fracture through the neck of the talus. This causes AVN of the body or entire talus, which is susceptible to infection (see FIG 1).

 

 

 

FIG 2 • CT scan of tibiocalcaneal arthrodesis. The excision of the talus creates a 3- to 4-cm bone defect.

 

 

76

PATHOGENESIS

 

High-energy ankle trauma

 

 

Postoperative infection of open reduction and internal fixation of talus fractures Postoperative infection of ankle arthrodesis and ankle replacement

PATIENT HISTORY AND PHYSICAL FINDINGS

 

 

Painful ankle with swelling and local inflammation Ankylosis of the hindfoot and ankle

 

Shortening of the extremity

 

A draining sinus indicates a deep infection.

 

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

An ankle series of radiographs will reveal the extent of the bone loss, the extent of AVN, and the location of internal fixation hardware in the talus and plafond (FIG 3).

 

There may be local bone erosion of the talus, plafond, and malleoli from the chronic infection in the joint.

 

 

 

FIG 3 • A,B. Anterior and lateral x-ray of ankle with infected nonunion of talus. The ankle had a draining sinus. The talar body is avascular and the talar head has bone lysis around the two fixation screws. The plafond has erosion and destruction of the cartilage. There is reactive bone on the medial malleolus compatible with infection.

 

 

A white blood cell count, erythrocyte sedimentation rate, and C-reactive protein study are screening tests that will indicate the possibility of a deep infection.

 

Aspiration of the ankle joint under fluoroscopic guidance is indicated if there is suspicion of an infection.

 

Computed tomography (CT) scanning will define the fragmentation of the talus and may reveal erosions of the plafond and malleoli compatible with infection.

 

Magnetic resonance imaging (MRI) will have diffuse signals caused by the fracture and inflammation that will provide little useful data in making the diagnosis.

 

DIFFERENTIAL DIAGNOSIS

Charcot joint

 

 

NONOPERATIVE MANAGEMENT

 

The patient may use a cane and ankle brace to improve gait.

 

 

There will be chronic pain with AVN of the talus, infection, or traumatic ejection of the talus. There is no conservative treatment for an infected nonunion of the talus.

 

Treatment with oral or intravenous antibiotics will only suppress the infection.

 

SURGICAL MANAGEMENT

Preoperative Planning

 

Infection of the talus is treated with aggressive débridement. Oral antibiotics should be discontinued 2 weeks before the débridement to obtain accurate cultures.

 

If there is infection and drainage that requires emergent débridement, the patient is taken to surgery and deep cultures are obtained before starting intravenous antibiotics.

 

It is essential to identify the infecting organism.

 

Mycobacterium, yeast, and aerobic organisms may be the source of an infection, and cultures should be obtained.

 

The organisms cultured in our series include methicillinresistant Staphylococcus aureus, Enterobacter cloacae, Escherichia coli, Staphylococcus aureus, Streptococcus (nonhemolytic), Alcaligenes xylosoxidans, and Pseudomonas aeruginosa.

 

TECHNIQUES

• Débridement of Infection

   

  Use an anteromedial approach located medial to the anterior tibial tendon to explore the talus (TECH FIG 1A).

   

   

  Before making the incision, elevate the leg for 3 minutes to drain blood from the extremity. Do not use an elastic compression bandage when there is a deep infection.

   

  Use a tourniquet during the initial excision of bone. Without a tourniquet, the field would be flooded with blood, obscuring the appearance of the infected bone.

   

  Carefully explore the infected talus.

   

  The necrotic bone will have a discolored avascular consistency.

   

  Necrotic bone tends to have a brittle consistency compared to viable bone.

   

  Excise the bone in small fragments, carefully observing for vascularity and the transition from necrotic infected bone to viable bone.

   

  The preoperative radiographic evaluation may not clearly identify the extent of infection.

   

  The talar head may be necrotic without the appearance of AVN on the radiograph.

   

  Remove all hardware as the talus is débrided.

   

  Take cultures from an area clearly involved with purulence.

   

  The infection and necrotic bone may be limited to the body of the talus, or the infection may have spread to the head of the talus, requiring excision of the entire talus (TECH FIG 1B).

   

  There may be a posteromedial section of the talus that is viable bone, but it is not large enough to be used for a pantalar arthrodesis.

   

  77

   

   

   

  TECH FIG 1 • A. Anteromedial approach with excision of the entire talus. B. The talus is excised in small fragments using a ¼-inch osteotome and pituitary rongeurs. This allows the entire talus to be removed without an extensive exposure. The bone is removed by working through the infected talus until the joint margins are cleared of all bone and cartilage. C. Débridement of the talus and distal plafond created a 5-cm bone gap. Antibiotic beads are placed in the ankle débridement.

   

   

   

  Once all necrotic bone is removed, lavage the joint with lowpressure saline and deflate the tourniquet.7 Viable bone will have punctate bleeding.

   

   

  If the margin of the bone resection does not bleed, excise the bone until bleeding is encountered. This may lead to excision of the talar head.

   

  The tibial plafond can have invasion of infection and require removal of the joint surface and metaphysis for several centimeters (TECH FIG 1C).

  Antibiotic Beads

   

  Antibiotic beads are manufactured on the back table.

   

  The beads should have a small diameter (7 mm) to allow complete filling of the irregular volume created by the excision of the necrotic bone.

   

  2.4 g of tobramycin powder is dry mixed with 1.0 g of vancomycin and crushed with the rounded end of a Cobb elevator until there is a fine powder.

   

  The antibiotics are dry mixed with 20 g of methylmethacrylate cement before adding the liquid monomer.

   

  Using this large amount of antibiotics causes the cement to mix poorly, and it must be mashed into a paste before making the beads.

   

  The cement is rolled into long 1-cm cylinders and cut into small pieces, which will form small-diameter beads.

   

   

  The beads are formed and placed on a no. 2 nylon suture that has had the heavy needle straightened. Fifteen to 20 minutes of drying time is needed for the beads.

   

  Once the beads have cooled, they are carefully packed into the wound to fill all of the space created by the talus excision (TECH FIG 1C).

   

   

  The beads can be divided into two strings. A half string usually fills the defect.

   

  The remaining beads are placed in a sterile container for repeat débridement if needed.

  Wound Closure

   

  Close the wound with 2-0 nylon suture.

   

   

  Because of the thorough débridement, the wound can be closed primarily. Copious postoperative hemorrhage will drain through the singlelayer closure.

   

  If the wound is left open, the edges will retract and a large open wound will develop that will take weeks to months to heal by secondary intention.

   

  If the infection was virulent, the patient is returned to surgery 24 to 48 hours later for a repeat débridement and bead exchange.

   

  The fibula is not excised at this time.

   

  With beads filling the defect and the fibula intact, the extremity is placed in a splint or fracture boot.

  Postoperative Care

   

  Broad-spectrum antibiotics that cover methicillin-resistant S. aureus and gram-negative rods are administered until the cultures have identified the infecting organism.

   

  The extremity and surgical wound are examined daily.

   

  If the wound does not rapidly improve, a second débridement is indicated.

   

  After a week of intravenous antibiotics, the ankle is ready for tibiocalcaneal arthrodesis.

   

   

  Extending the intravenous antibiotic course for 2 to 3 weeks and further observation may be indicated if the condition of the extremity requires further time to be ready for surgery.

   

• Tibiocalcaneal Arthrodesis

78

 

Technically, the most difficult aspect of the surgery is fitting the concave surface of the plafond to the asymmetric surface to the posterior facet of the calcaneus, anterior calcaneus, and neck of the talus or the navicular (TECH FIG 2A).

 

 

 

TECH FIG 2 • A. Fitting the incongruent surfaces of the tibial plafond to the calcaneus and talar neck or navicular requires craftsmanship. The osteotomy cuts are made with small cuttings until a stable compression surface is created. B. The anterior plafond is cut to align with the talar neck when the talar head is viable (white arrow). The posterior plafond osteotomy requires an oblique osteotomy to fit the posterior facet of the calcaneus (striated arrow). C. The anterior prominence of the tibial plafond is not removed when the talar head has been excised (black arrow). The anterior cortex is prepared to bleeding bone. The bone resection of the posterior plafond is shaped to fit the posterior facet (gray arrow). The resection of the posterior plafond is less because the tibia is located anteriorly with the talar head excised. The anterior process of the calcaneus is leveled to allow the tibia to compress onto the calcaneus. D. An inferior to superior Steinmann pin is placed to align the calcaneus with the tibial shaft after the arthrodesis osteotomies have been completed (black arrow). One or two Steinmann pins are placed from posterolateral through the plafond into the head of the talus to improve stability of the fixation if the talar head is preserved in the reconstruction. E. Acute shortening causes the soft tissues to bulge in the horizontal plane. After the calcaneal tibial pin is in place, the wounds can be closed with the extremity distracted. The tibia is compressed to the calcaneus after closure. Shortening causes distortion of the blood vessels crossing the ankle. Vascular flow must be carefully monitored after shortening. F. Monofocal tibiocalcaneal talar head arthrodesis circular fixator. The frame consists of a double-ring fixation block and a foot fixation ring. The fixator is used to compress the arthrodesis. This illustration represents reconstruction of a talus with a viable talar head. G. Bifocal tibiocalcaneal navicular arthrodesis circular fixator. The frame incorporates a proximal ⅝-full ring block and corticotomy to combine proximal

lengthening with distal compression. The illustration depicts reconstruction after complete excision of the talus. H. Clinical photograph of bifocal fixator. Observe proximal ⅝-full ring block connected to double-ring midtibia fixation block with distraction clickers. The foot frame is compressed with square nuts. Observe open lateral traumatic wound which will heal by secondary intention.

 

 

Cut the bone away in small shavings, with multiple trial fittings until the plafond fits securely into the calcaneus and talus or navicular.

 

 

Approach the plafond and calcaneus from the lateral and medial sides of the ankle.

 

 

Retention of the lateral malleolus is of no benefit.

 

79

 

Excise the lateral malleolus through a lateral excision and perform an osteotomy 5 to 6 cm proximal with an oblique cut superolateral to inferomedial.

 

Carefully elevate the fascia overlying the lateral malleolus from the surface.

 

This fascia provides a deep closure of the lateral tissues after completion of the osteotomy.

 

The lateral approach exposes the posterior facet of the calcaneus, lateral calcaneus, and anterior process.

 

Do not extend the vertical excision past the level of the peroneal tendons to prevent injury to the sural nerve.

 

 

The anteromedial approach exposes the navicular, talar neck, and medial facets of the calcaneus. Evaluate the plafond and posterior facets of the calcaneus.

 

If the posterior facet is intact, excise the cartilage and expose the subchondral bone to bleeding bone.

 

Débride the medial facet of cartilage and level the facet with the middle and anterior calcaneus.

 

Cut the posterior plafond at an angle to match the posterior facet and remove the cartilage from the central plafond (TECH FIG 2B,C).

 

If the talar neck is viable, cut the anterior plafond away to match the plane of the talar neck and flatten the underside of the anterior plafond to match the contour of the middle and anterior calcaneus (see TECH FIG 2B).

 

Cut away small amounts of bone from the tibia and calcaneus until there is a good fit between the tibia and calcaneus.

 

Assess the alignment of the calcaneus with the tibia.

 

With the tibia compressed onto the calcaneus, the sole of the foot and heel should be in a foot-flat position.

 

 

The foot should be rotated straightforward or in slight external rotation. Equinus must be avoided.

 

Neutral plantarflexion and slight dorsiflexion are functional positions.

 

If the arthrodesis is in equinus, the patient must wear shoes with a heel wedge to accommodate this malposition.

 

The osteotomies of the tibia plafond and calcaneus must be fitted so that when the tibia is compressed onto the calcaneus, the fit of the osteotomy forces corrects alignment of the foot.

 

If the osteotomies are not correct, the compression applied by the circular fixation will malalign the arthrodesis.

 

The bone cuts of the anterior plafond are modified if the talar head has been excised because of infection (TECH FIG 2C).

 

Denude the navicular of cartilage to bleeding bone.

 

 

Shape the bone contour of the anterior plafond to match the navicular concave surface. Flatten the anteroinferior plafond to fit the anterior calcaneus.

 

The tibia is located in an anterior position toward the midfoot compared to the arthrodesis position if the talar head is present.

 

Because of this anterior position, the osteotomy of the posterior plafond may require less bone resection.

 

Always align the plafond over the calcaneus and slowly cut away bone until there is a good fit of the bone surfaces.

 

After completing the osteotomies, copiously lavage the operative field with low-pressure bulb irrigation to remove debris before closure.

 

 

The use of high-pressure pulsed irrigation destroys the exposed trabecular bone.7 Deflate the tourniquet and examine the bone surfaces for punctate bleeding.

 

If there is no bleeding, further bone resection is needed until viable bone is observed.

 

Compress the calcaneus and align it manually, and drill a smooth Steinmann pin through the plantar surface into the tibial shaft (TECH FIG 2D).

 

This pin will guide the calcaneus to the correct position during compression with the circular fixator later during the technique.

 

Close the medial and lateral incisions with a deep layer of absorbable suture and the skin with vertical nylon mattress sutures.

 

The sutures may need to be in place for 3 to 4 weeks before there is adequate wound healing.

 

Never use staples for the skin closure.

 

The shortening of the calcaneus onto the tibia will cause the soft tissues to expand in the horizontal plane (compression of a cylinder causes expansion of the diameter of the cylinder) (TECH FIG 2E).

 

To facilitate closure, distract the calcaneus on the Steinmann pin and close the wounds with the foot out to length.

 

The amount of edema and fibrosis of the soft tissue will affect the ability to acutely shorten the arthrodesis.9,13

 

If there is severe edema and fibrosis, an acute shortening may not be possible and a delayed shortening may be required to compress the arthrodesis.

 

The surgeon will gauge the effect of the shortening.

 

If the calcaneus is compressed against the plafond and the foot becomes cyanotic, a delayed shortening will be needed for the reconstruction.

 

The circular fixator is constructed as a monofocal frame or as a bifocal frame (TECH FIG 2F,G).

 

 

The circular rings are sized to provide 2 cm of soft tissue clearance. Most frames are constructed with 160- or 180-mm rings.

 

If the patient is a candidate for proximal distraction osteogenesis, the frame is assembled with a proximal

⅝-full ring block, a midtibial double-ring fixation block, and a foot fixation block.

 

If the patient has poor physiology for lengthening (end-stage diabetes, tobacco abuse, ischemic vascular disease, steroid dependency, or psychosis), the frame is assembled as a monofocal frame with a two-ring tibial fixation block and a foot fixation block.

 

Carefully assess the ability of the patient to undergo distraction histogenesis.

 

If there is failure of the arthrodesis, the salvage is a below-knee amputation.

 

If a proximal corticotomy has been done on a patient with poor physiology, the below-knee level of salvage could be lost.

 

80

• Proximal Lengthening

 

The proximal and midtibial ring blocks are assembled as a unit.

 

The proximal ring block is constructed with a ⅝ or ⅔ ring connected to a full ring with three 3.0-cm hexagonal sockets (TECH FIG 3A).

 

The midtibial ring block is constructed with two rings connected with four 120- or 150-mm threaded rods (TECH FIG 3B,C).

 

The proximal and midtibial ring blocks are connected with four 40-mm distraction telescopic rods (clickers).

 

A horizontal reference olive wire is placed 15 mm below the tibial plateau with a 3-degree varus alignment.

 

The varus of the reference wire aligns the frame with the axis of the tibia shaft (TECH FIG 3D).

 

 

The frame is aligned and centered on the tibia with adequate soft tissue clearance (TECH FIG 3E). Observe the posterior gastrocsoleus muscle to ensure proper clearance.

 

Tension the horizontal reference wire to 110 kg.

 

The center of the frame should align with the tibial shaft.

 

If the alignment is not axial, washers can be placed under the lateral or medial reference wire to correct the alignment.

 

During this phase of the procedure, an assistant must support the distal leg and foot to prevent distorted positions, which could injure the soft tissues.

 

A towel block under the heel also prevents displacement.

 

Align the distal tibial ring block with the tibia and place a 5-mm half-pin in the anteroposterior (AP) plane. Secure it with a universal Rancho cube on the distal ring (TECH FIG 3F).

 

The universal cube allows the ring to be aligned on the lateral view in an orthogonal position.

 

Alternatively, a transverse olive wire may be used to align the distal fixation block (see TECH FIG 3C).

 

 

 

TECH FIG 3 • A. The ⅝-full ring proximal fixation block. The ⅝ ring is connected to the full ring by three 3-cm hexagonal sockets. The horizontal reference wire is 15 mm below the joint in 3 degrees of varus. A smooth wire is placed into the fibula head. If the fibula head is not fixated, the fibula will be dragged down the leg with lengthening. A medial face wire is placed on the inferior surface of the full ring. A 5-mm half-pin is placed anteromedial after completion of the corticotomy. The ⅝ ring is rotated to the lateral side to allow placement of the fibula head wire. B. The tibial shaft double-ring fixation block is aligned orthogonally on the tibia with two AP 6-mm half-pins mounted on universal Rancho cubes. The Rancho cube mountings allow the fixation block to be aligned orthogonally. One or two medial pins are added once the fixation block is aligned. The distal ring is located about 6 cm superior to the arthrodesis. (continued)

 

 

 

Once the frame is aligned, place a second AP 5-mm half-pin on the midtibial fixation block. Place a medial half-pin between the rings aligned 90 degrees to the two AP pins.

 

Place a second medial pin for large patients.

 

Further stabilize the proximal ⅝-full ring block with a medial face olive wire on the inferior face of the full ring and place a smooth wire through the fibula head, exiting the anteromedial tibial plateau.

 

Connect the footplate to the midtibial fixation block with two threaded rods placed in the posteromedial and posterolateral ring (TECH FIG 3G).

 

The rods should have about 50 mm of excess length.

 

 

 

Place a horizontal reference wire in the tuberosity of the calcaneus from lateral to medial. Compress the foot on the Steinmann pin until the calcaneus is in alignment with the tibia. Manipulate the foot on the footplate to control rotational alignment and align the arthrodesis.

 

 

 

Close the footplate anteriorly with a half-ring before tensioning. Tension the wire to 100 kg and tighten the slotted fixation bolts. If the alignment is not satisfactory, repeat the process.

 

Connect two threaded rods to the anterior footplate with threaded rods using extension plates from the

stable base.

 

 

81

 

 

 

TECH FIG 3 • (continued) C. An alternative method to align the stable base is to place a horizontal reference above the plafond. The wire should be placed posterior on the shaft to avoid the anterior tibial artery. The distal wire is located about 6 cm proximal to the arthrodesis. D. The joint surface of the plateau forms a varus 87-degree angle with the shaft. A horizontal reference wire placed 90 degrees to the shaft will be slightly closer to the medial plateau compared to the lateral. E. The proximal ⅝ ring block and the tibial shaft double-ring block are connected by 40-mm distraction rods. The frame is aligned on the proximal reference wire followed by a 5-mm half-pin placed on the distal ring. Manipulating these two fixation points aligns the frame orthogonally on the tibia. The rings must have soft tissue clearance at the posterior gastrocnemius muscle and anterior ankle soft tissue prominence. F. Universal Rancho cube pin fixation. Three-axis adjustment of the pin alignment allows the frame to be aligned orthogonally with the tibia. Rancho cubes bolted directly to the ring; fix the ring in the alignment of the half-pin. If the half-pin is not perfect, the ring block will be malaligned. G. The foot fixation block is constructed with a long footplate closed on the anterior open end with a half-ring. The ring extends above the toes to keep bed linen from irritating the toes. The surgeon should avoid wires that could penetrate the posterior tibial or plantar nerve. Two opposed olive wires are placed in the calcaneus and two opposed olive wires are placed in the forefoot.

 

 

Stabilize the forefoot with opposed olive wires through the cuneiform row and metatarsal bases.

 

Place a second wire from the posteromedial calcaneal tuberosity to the anterolateral calcaneal wall on the superior side of the footplate.

 

Assess the vascularity of the foot with the foot in the acutely shortened position.

 

There should be brisk capillary refill.

 

Use a Doppler device to verify pulsatile flow in the dorsalis pedis and posterior tibial artery.

 

If the vascular flow is good, maintain the foot in the acute shortened position.

 

If the foot is cyanotic and no pulses are detected with the Doppler, slowly distract the foot by lengthening the threaded rods between the tibial fixation block and the foot ring.

 

Once pulsatile flow is detected, lock the threaded rod position in place.

 

This position will create a gap between the tibia and calcaneus.

 

 

A delayed shortening is used to close this gap slowly over several days (TECH FIG 4). The gap is closed at a rate of 1 mm four times a day until the arthrodesis is compressed.

 

82

 

 

 

TECH FIG 4 • The technique of delayed shortening. The foot fixation block is compressed at a rate of 1 mm four times a day until the tibiocalcaneal arthrodesis is compressed. The calcaneal tibial Steinmann pin aligns the foot during the compression. The proximal tibia is lengthened to equalize leg lengths.

 

 

If the distal tibia plafond has extensive bone loss creating a bone deficit greater than 5 cm, the tibiocalcaneal arthrodesis can be accomplished with an intercalary transport (TECH FIC 5).

 

Reinflate the tourniquet and complete a corticotomy using an osteotome or a Gigli saw.

 

After the corticotomy, place a 6-mm half-pin on the medial side of the tibial tubercle from anterior to posterior.

 

The Steinmann pin is maintained for 6 weeks after surgery, which stabilizes the arthrodesis site.

 

 

 

TECH FIG 5 • The technique of intercalary transport to arthrodesis. A. Infection of plafond and talus. B. Excision with bone gap greater than 5 cm. C. Ilizarov frame maintaining leg length before transport. D. Intercalary transport to docking. A revision of the docking site will improve alignment. A spatial frame could also be used in this configuration. Large defects can also be closed with an acute shortening of 3 cm combined with an intercalary transport to close the gap. The circular fixator is converted to a lengthening frame to equalize the leg length.

 

 

Place two more Steinmann pins from the posteromedial plafond into the talar head or navicular after compressing the arthrodesis (see TECH FIG 2D).

 

These pins stabilize motion between the talar head and tibia, increasing arthrodesis between these structures.

• Techniques without Lengthening

 

Apply a stable base to the distal tibia (see TECH FIG 3B).

 

 

Place two AP half-pins on universal Rancho cubes and align the ring block orthogonally. The distal ring is located about 6 cm above the arthrodesis site.

The ring is further stabilized with one or two 5-mm halfpins placed into the medial tibia.

An alternative method is to place a horizontal reference wire 6 cm above the ankle and align the double-ring fixation on the wire and place two AP pins and a medial face half-pin on the ring block (see TECH FIG 3C).

In patients with osteopenia, the entire fixation block can be fixated to the tibia with four olive wires placed in safe corridors.

Complete the arthrodesis of the tibia to the calcaneus as described in the prior section.

 

 

83

 

PEARLS AND PITFALLS

 

 

• The arthrodesis must be in a plantar neutral position. A fusion with the foot in equinus will severely compromise the functional outcome (FIG 4).

 

 

FIG 4 • A. Tibiocalcaneal arthrodesis with loss of talar head and navicular in crush injury of foot. B. Full lateral x-ray of tibia and foot is accurate method to evaluate foot position. With no ankle motion and compromised forefoot motion, aligning the foot in plantar neutral position and correct forefoot rotation is

 

 

essential for a functional result. Observe mature proximal bone transport to equalize leg length.

 

 

POSTOPERATIVE CARE

 

The foot is observed for blood flow every 4 hours for the first two postoperative days.

 

 

If the foot becomes ischemic, the threaded rods connecting the foot frame to the tibia fixation block are lengthened until the blood flow improves.

 

 

A delayed shortening is then carried out until the arthrodesis is compressed (FIG 5). The patient is encouraged to mobilize the forefoot and toes and knee.

 

Toe loops on rubber bands are placed on a wire scaffold to prevent toe flexion contractures by the physical therapy service.

 

 

 

FIG 5 • A. Lateral x-ray of bifocal external fixator. The proximal tibia has been lengthened between the ⅝-full ring block and the double-ring block on the midtibia. B. Lateral x-ray of the tibiocalcaneal arthrodesis with compression between the midtibia and the footplate. The foot is in plantar neutral alignment. C. Mature tibiocalcaneal arthrodesis with the plafond fused to the calcaneus and navicular. D. AP x-ray with axial alignment of arthrodesis. The patient had a valgus deformity after frame removal of the transport. The tibia was realigned with a lateral locked plate.

 

 

There will be significant bloody drainage and the bulky dressing placed in surgery may need to be changed on the first postoperative day.

 

 

Open wounds are treated with normal saline wet-to-dry dressings until closure by secondary intention. Vacuum dressings are an alternative to wet-to-dry dressings.

 

The sutures are left in place for at least 2 weeks.

 

Many patients will require 3 to 4 weeks of suture closure before it is possible to remove the sutures.

 

Intravenous antibiotics are administered for 2 days in patients without infections.

 

If the wounds are complex, the intravenous antibiotics will be continued for 7 days.

 

 

84

 

Patients with infected talus nonunions will be treated for additional weeks using intravenous antibiotics appropriate for the infecting organism.

 

There is debate on whether the antibiotics need to be given for an additional week or continued for a total of 6 weeks during the treatment course.

 

The dressing sponges are removed 2 weeks after surgery, and the pin sites are cleaned daily.

 

Once the surgical wounds are healed, the leg is washed in the shower with soap and water, removing all dried secretions from the pins and wires.

 

 

Hydrogen peroxide 3% solution is used only occasionally to clean crust that cannot be removed with soap and water.

 

Cephalexin, trimethoprim-sulfamethoxazole (Septra DS), and ciprofloxacin are used if needed to control local pin or wire skin infections.

 

Some patients will need only occasional use of antibiotics, whereas others will require constant oral antibiotic coverage while the circular fixator is on the leg.

 

Rarely, a more aggressive pin or wire infection will develop.

 

The infecting organism is most commonly methicillinresistant S. aureus.

 

 

A 1-week course of intravenous vancomycin will be needed to control the wire infection. If this is not successful, the wire is removed.

 

The plantar and talar neck and navicular Steinmann pins are removed in the clinic 6 weeks after surgery.

 

 

 

The patient is started on partial weight bearing, increasing to 50% weight over the following month. A shower sandal is placed over the toes when walking.

 

The sandal is elevated with a full sole elevation to equalize the leg lengths, and the sole is cut down on the band saw as the lengthening progresses.

 

Most patients cannot tolerate full weight with wires in their foot.

 

Lengthening proximally is at a rate of 0.25 mm (one quarterturn) twice a day.

 

 

Younger patients can distract at a rate of 0.25 mm every 8 hours.

 

 

The lengthening is started 3 to 4 days postoperatively after the patient's pain has improved from the surgery. The starting rate is always 0.25 mm twice a day.

 

If the patient forms robust new bone, this can be increased to 0.25 mm every 8 hours.

 

The leg is lengthened until the leg length is equal (see FIG 4).

 

 

Given the choice, most patients request equal leg length rather than on to 2 cm of shortening. The distraction index is between 1.5 and 2.0 months per centimeter.

 

For a patient with tibial bone loss, the lengthening required can exceed 5 cm, resulting in 10 or more months in the circular fixator.

 

Some patients will heal the arthrodesis before the lengthening is mature.

 

The foot frame can be removed before the proximal transport is mature.

 

The tibiocalcaneal arthrodesis requires 6 months for union.

 

 

The footplate is compressed 1 or 2 mm at each clinic visit to maintain compression over the course of treatment.

 

The fixator is removed under anesthesia.

 

A short-leg walking cast is applied and the patient walks with partial weight bearing.

 

The patient continues partial weight gait until there is defined bone healing at the tibiocalcaneal arthrodesis and the proximal bone transport has a well-developed medial, lateral, and posterior cortex.

 

Often, patients will return to the clinic stating that they have advanced to full weight bearing around the house walking in the frame.

 

To increase the force transmitted across the transport, the frame is neutralized before frame removal.

 

This is accomplished by loosening the distraction clickers and allowing the distraction force to become neutral.

 

The rods are bolted in this neutral position and the patient is observed for several weeks to see if the cortex of the regenerate is strong enough to prevent collapse.

 

The fixator is removed under general anesthesia. The leg is casted for 2 weeks after frame removal.

 

The radiograph out of plaster in the office with the Ilizarov fixator removed is analyzed for healing of the transport bone and arthrodesis.

 

 

A fracture walking boot with a rocker bottom sole is applied. The patient walks 50% weight bearing for 4 weeks.

 

The patient advances to full weight bearing with a cane and gradually increases his or her activity over the following year.

 

Activity is limited to walking on flat surfaces and light stress on the extremity.

 

The force applied to the leg is gradually increased with mature healing of the bone transport and arthrodesis observed at 1 year after fixator removal (FIG 5C,D).

 

The patient self-selects walking and training shoes that have cushioned heels with a rounded radius heel.

 

Patients who do not have proximal bone transport to equalize leg length have full sole elevations of 3 to 5 cm added to their walking shoes (shoe prosthesis) with a rocker sole.

 

If the patient has mild valgus or varus foot alignment, an orthotic is prescribed that improves their foot loading when standing and walking.

 

Long-term follow-up reveals osteophyte development at the talar navicular joint, which is associated with arthritic pain.

 

 

OUTCOMES

The average American Orthopaedic Foot and Ankle Society (AOFAS) foot and ankle score was 65 for the 11 patients in our case series.12

We have reconstructed three further patients with good result for total of 14 cases. Patients lose the ability to participate in sports and work as laborers.

 

The work status is reduced to light or sedentary work. They can still ride motorcycles and drive cars.

Patients are aware of the asymmetry of their legs from atrophy of the muscles motorizing the foot and ankle.

When queried, no patient to date has considered having an amputation. The long-term follow-up will probably reveal progression of midfoot arthritis.

 

 

85

 

COMPLICATIONS

Failure of the bone transport to mature is a major complication.

The distraction index is between 1.5 and 2.0 months per centimeter of lengthening.

Bone growth is stimulated by weight bearing, so during the treatment course, the patient is encouraged to place 50% partial weight on the extremity.

An Exogen Bone Stimulator (Smith & Nephew, Memphis, TN) can be used once the distraction is completed.

Bone grafting of the distraction can also stimulate maturation if poor bone formation is observed.

If deformation of the transport occurs after frame removal, this problem can be treated by several methods.

If there is less than 5 degrees of angulation, the patient is treated with a knee brace and non-weight bearing for 6 weeks.

If greater deformity is observed, a second circular fixator is applied with angular correction and further time in the frame is indicated.

An alternative is to place a locked plate spanning the transport on the medial or lateral tibial shaft (FIG 5D).

An intramedullary nail can also be used for bone transport with poor bone formation.

 

 

 

 

FIG 6 • A. Nonunion of tibia metaphysis to calcaneus and talar head remnant following Ilizarov compression. B. Revision of docking site with Steinmann pin fixation through calcaneus into tibia and Steinmann pin fixation of talar head to anterior metaphysis of tibia. C. Revision frame with two-ring fixation block on distal tibia and foot fixation ring. Distal closing ring on footplate is offset with hexagonal socket to clear toes. Rubber band stirrups prevent flexion contracture of toes. D. Foot is aligned in frame plantar neutral. Wire pathways through foot illustrated. E. Seven-year follow-up of tibiocalcaneal arthrodesis. Observe reactive bone at talar navicular joint. F. Ninety-degree foot alignment and healed complex wound. It is essential to avoid any equinus position of the foot. G. Alignment of foot with the floor. Slight varus of heel. Ideal position equally loads first and fifth metatarsal heads.

 

 

 

The pin and wire tracks must be free of infection to use internal fixation after external fixation. The patients walk 50% partial weight with crutches until healing of the transport.

 

Failure to achieve arthrodesis is directly related to the physiologic status of the patient.

 

If union has not occurred by 6 months of frame time, further time in the frame will not alter the outcome.

 

If the patient is not on steroids and is in reasonable health, a revision arthrodesis is attempted. The docking site is explored, and fibrous tissue is removed. The bone surfaces are revised to bleeding bone (FIG 6).

 

Patients with rheumatoid arthritis who are using steroids chronically are prone to nonunion of their

tibiocalcaneal arthrodesis.

 

Patients with rheumatoid arthritis are placed in a cast and encouraged to walk.

 

The mobile nonunion forms a pseudojoint similar to fascial arthroplasty that allows them to walk independently (FIG 7).

 

We have observed four patients who have maintained this pseudojoint for years and are able to participate in activities of daily living.

 

 

86

 

 

 

 

FIG 7 • A,B. Bilateral tibiocalcaneal arthrodesis nonunion after failed infected ankle arthrodesis and infected total ankle arthroplasty. The patient is on high doses of steroid medication. The infections were eradicated.

C. Clinical photograph of bilateral tibiocalcaneal nonunion with fibrous pseudojoint. Observe the free flap on the medial ankle. The patient uses a scooter for traveling distances but can walk independently and is independent in activities of daily living.

 

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