Secondary Logo

Journal Logo

TECHNIQUE

Arthrodesis Techniques for Avascular Necrosis of the Talus

ROYER, CHRISTIAN M.D.; BRODSKY, JAMES W. M.D.

Author Information
Techniques in Foot & Ankle Surgery: September 2002 - Volume 1 - Issue 1 - p 50-59
  • Free

Abstract

The treatment of avascular necrosis of the talus is a perennial dilemma and its treatment remains controversial. In 1943, Blair described the use of a sliding anterior tibial bone graft to fuse the distal tibia to the head and neck of the talus, excising the talus but without tibiocalcaneal arthrodesis. 1 This technique was modified by Morris et al. to include internal fixation in a effort to improve arthrodesis rates, with excellent or good results in all 10 patients treated. 2 In 1982 Lionberger et al. described a modification of the Blair technique to fuse the distal tibia directly to the head and neck of the talus. Arthrodesis was obtained in all five patients with talar avascular necrosis (AVN). 3

Tibiocalcaneal arthrodesis is also an option for treatment of severe fractures or AVN of the talus. Originally suggested by Albert in 1879, 4 several different techniques have been described. Myerson et al. reported on use of an adolescent condylar blade plate and allograft bone to achieve arthrodesis with severe ankle and hindfoot deformity. 5 Arthrodesis was obtained in 28 of 30 patients in an average of 16 weeks. In 1995, Mann and Chou reported 100% arthrodesis rate in nine feet with fixation obtained using staples or screws. 6

Dennison et al. have recently proposed use of an Ilizarov frame for simultaneous tibiocalcaneal arthrodesis and bone transport in an effort to overcome the problem of shortening of the limb, which occurs after tibiocalcaneal arthrodesis. 7 In six patients with avascular necrosis of the talus, arthrodesis was achieved in all, and four of the six had leg lengths equalized by lengthening the limb a mean length of 35mm. The average length of time the Ilizarov was applied was 11.5 months.

Choosing the best technique for arthrodesis of the ankle and/or the subtalar joint in the presence of AVN of the talus has been controversial, given the poor quality of the talar body. Russotti et al. reported on 21 patients who underwent tibiotalocalcaneal arthrodesis, four of whom had AVN of the talus. 8 They reported good results with use of autogenous bone graft placed posteriorly and fixation with an intramedullary Steinmann pin and Calandruccio external fixator. The intramedullary concept for TTC arthrodesis was further advanced with the use of a intramedullary nail. 9,10,11 Kile et al. found this to be an “effective salvage for patients with posttraumatic degenerative arthrosis or avascular necrosis . . .”. 9

Isolated ankle (tibio-talar) arthrodesis as an option for treatment of AVN of the talus has also been described. In a series by Kitaoka and Patzer, all three patients who underwent isolated tibiotalar arthrodesis for AVN of the talus united. 12 Internal screw fixation is most commonly used for this type of arthrodesis. In 1991, Holt et al. described using three screws, with the most important screw placed posterolaterally in the tibia and directed into the head and neck of the talus. 13 However, they did note that AVN of the talus placed patients at a higher risk for nonunion.

INDICATIONS/CONTRAINDICATIONS

The two goals of treatment of patients with avascular necrosis of the talus is the typical goal of foot and ankle reconstruction; namely, a plantigrade and relatively painless foot. The foot must also be functional and stable. Evaluation of the patient should begin by determining how the pain affects their life on a daily basis including limitations of activities on the job and in recreation. The quality and duration of the pain should be noted as well. The location of the pain is important in considering surgical options. It is critical to isolate which joints are affected, because pain localized to just the ankle joint may be treated with an ankle arthrodesis, however pain at both the ankle and subtalar joints may require a tibiotalocalcaneal arthrodesis. The stability of the foot must also be evaluated. Instability about the hindfoot, which cannot be controlled externally, is another indication for hindfoot arthrodesis.

Soft tissue concerns must be considered in treatment of the patient. Trauma or previous surgery may have compromised the surgical area. Vascularity of the extremity should be evaluated before the surgical procedure. Local or systemic vascular insufficiency may compromise both bony and soft tissue healing. These insufficiencies may also be considered a contraindication to surgery, and should be addressed before surgery by appropriate consultation with vascular and plastic surgery colleagues.

Conservative treatment may delay or even prevent the need for hindfoot arthrodesis in some cases. Dennison et al. found an average time of 56 months from the time of injury until operation in patients with AVN of the talus. 7 Lifestyle and activity change to decrease stress on the affected joints should be considered a first step for a patient with this condition. Nonsteroidal anti-inflammatories, nonnarcotic analgesics, glucosamine and chondroitin sulfate, or any combination of these may also provide some significant relief. The use of external immobilization devices such as pre-fabricated walking boots, custom polypropylene ankle-foot orthoses, or even casting can be very effective. However, many patients do not tolerate either the inconvenience or altered cosmesis of conservative care, and realistically this is a factor in surgical decision-making for many patients.

PREOPERATIVE PLANNING

Initial preoperative planning involves a thorough physical exam to determine the location of the pain. The pain may be isolated to the ankle or involve the subtalar and possibly transtarsal joints. Motion at each of the joints should be recorded. According to Mann, approximately 30% of patients who undergo hindfoot athrodesis develop arthritis in joints proximal or distal to the arthrodesis within 5 years. 14 Any deformity, fixed or reducible, in the foot should be noted. Severe fixed valgus of the hindfoot may lead to a planus deformity at the midfoot and supination of the forefoot, which may need to be corrected at the time of hindfoot arthrodesis with either midfoot osteotomies or arthrodeses.

Preoperative radiologic evaluation before surgery should include complete weightbearing radiographs of both the foot and the ankle. In some patients, radiographs of the contralateral extremity are useful to determine positioning of the arthrodesis. The extent of the avascular necrosis of the talus is very valuable in planning arthrodesis technique and bone grafting. This should be evaluated with CT scan or MRI. We prefer MRI to evaluate the quality of the bone. Swanson et al. found that MRI could detect AVN more accurately than plain x-ray in 21 patients. 15 They also found that two patients had collapse of the body. Both had AVN, which involved more than 50% of the body. Though no specific studies have been completed to determine the effect on arthrodesis rates, it has been a generally accepted orthopaedic concept that at some unknown threshold, more extensive AVN will presumably decrease union rates, because there is less live bone to participate in the healing process. Consideration of the extent of the AVN often alters the type of arthrodesis technique that is chosen. For example, a tibiocalcaneal arthrodesis may be more successful than a tibiotalocalcaneal arthrodesis if the entire body of the talus is avascular. However, a tibiotalocalcaneal fusion with bone graft can be attempted and may be successful despite total body involvement.

Our algorithm for treatment depends on the amount of AVN. If the amount of AVN is found to be minimal (10–25%), then debridement of the avascular talus and fusion without the use of bone graft is completed. Avascular necrosis involving 50% of the body may necessitate debridement of the avascular talus and bone grafting. We prefer autograft from the proximal tibia. Whether the fusion is an isolated tibiotalar fusion or tibiotalocalcaneal depends on the involvement of the subtalar joint. If the subtalar joint is well maintained and subtalar motion is painless, then this joint may be spared.

If there is avascular necrosis of the talus involving 50–100% of the body, then either a partial resection with Blair type fusion or total talectomy is completed and a tibiocalcaneal fusion performed. Autograft is placed in the site to encourage healing.

Each of the techniques is described in the following sections.

TECHNIQUES

Tibiotalocalcaneal Arthrodesis

The author's preferred method of tibiotalocalcaneal arthrodesis is with the use of a retrograde intramedullary nail (Figs. 1 and 2). The patient is placed in a supine position on the operating table. A bolster is placed under the ipsilateral hip to allow easier access to the lateral and postero-lateral ankle. The limb is elevated and exsanguinated, and the thigh tourniquet is inflated to 300 mmHg. A 10 cm incision is made over the fibula in longitudinal fashion and carried distal to the sinus tarsi. This allows access to both the ankle and subtalar joints. Care should be taken to create full thickness flaps from skin to periosteum. The dissection is in the internervous plane between the lateral branch of the superfiscial peroneal nerve and the sural nerve, taking care to protect and retract these nerves. Using the large saw the distal fibulectomy is completed approximately 5 centimeters above its distal tip. This portion is preserved for use as a corticocancellous graft.

FIG. 1.
FIG. 1.:
Intramedullary nail.
FIG. 2.
FIG. 2.:
Intramedullary nail with insertion jig.

Debridement of the ankle joint is then achieved with hand instruments such as curettes, osteotomes, and rongeurs to debride the remaining articular cartilage, sclerotic bone, and fibrous tissue. Extreme sclerosis of the avascular talus may be noted. Using straight osteotomes, the subchondral bone is removed from the distal tibia and talar dome. The goal is to create two clean and maximally viable cancellous surfaces for arthrodesis. Congruency of the two surfaces is important to enhance the contact area for union. It is important to debride the opposing sides of the medial aspect of the talar body and medial malleolus. This can be accomplished with a curved curette. A second incision anteromedially may be necessary to gain access to this area. A similar process is carried out to denude the subtalar joint, usually aided by distraction with a small lamina spreader. Care is taken to prepare all three facets of the subtalar joint. After irrigation to remove all particles of bone and soft tissue from the arthrodesis sites, the surfaces are roughened to encourage bleeding at the bone surfaces either with a narrow osteotome (by “fish-scaling”) or with a 3.5 mm drill.

Once all surfaces of both joints are prepared, a transverse incision is made on the plantar heel, at a point directly below the midpoint between the anterior and posterior edges of the medial malleolus. Blunt dissection is done down to the calcaneous, retracting the soft tissue to avoid injury to the lateral plantar nerve and artery. 16,17 Under fluoroscopic control, the guide wire is then driven from the plantar calcaneous, through the talus and into the medullary canal of the tibia. It should be noted that the medullary canal of the tibia lies somewhat medial to the insertion site in the calcaneus, because the distal portion of the calcaneus (the anterior process) is laterally placed. This process can be aided by “medialization” of the talus in the mortise at the time of the debridement. This is achieved by thorough debridement, sometimes with additional bone removal from the opposing sides of the medial malleolus and medial talus. Subsequently, the guide wire may need to be advanced in a slightly medial direction to enter the canal. McGarvery et al. described a technique of medialization by excision of the medial malleolus and translation of the tibia. 18

The correct position of the hindfoot in both the sagittal and coronal planes should be maintained during insertion of the guide wire. The ankle should be in 5 degrees of valgus, neutral dorsiflexion/plantar flexion, and external rotation equal to that on the opposite side. 19 Once the position of the guide pin is verified, the reaming is completed with successively larger reamers at 0.5 mm increments. Over-reaming of 0.5 mm over the size of the nail is performed. Most common sizes of the nails are diameters of 10–12 mm, and a length of 15 cm, although occasionally longer lengths of 15 or 18 cm are used. Prior to placement of the nail, the corticocancellous graft from the fibula should be inserted into both the ankle and subtalar arthrodesis sites. Some of the graft is retained for placement after completion of the fixation.

The nail is then gently positioned over the guide wire and tapped into the tibia until the nail is even with the plantar surface of the calcaneus. Some prominence of the nail is common, if not unavoidable, but excessive prominence may cause discomfort for the patient when walking. The interlocking screws are then placed, and the order depends upon the particular nail system used, because each achieves compression by a different mechanism. It is important to remember to slightly internally rotate the nail to avoid the fibula when placing the screws in the tibia. While most of these nails are designed with the idea that proper positioning will result in screws neatly spaced in both the talus and the calcaneus, it is frequently not possible to achieve such idea spacing and positioning because of the salvage nature of these cases. Most of these patients have severe deformity, shortening, or bone loss, which necessitates this extensive procedure in the first place.

Any remaining bone graft can be applied to both arthrodesis sites. The arthrodesis sites are then covered with gelfoam. This serves two purposes. The first is to contain the peripheral bone graft in the arthrodesis sites. The second is to avoid adhesion of the graft to the delicate overlying soft tissue. The incisions are closed with 2–0 Vicryl and 3–0 Nylon in vertical mattress fashion. A suction drain may be used. A bulky, Jones-type, thick cotton dressing is then applied, followed by posterior and stirrup splints.

Case:

A 40-year-old female involved in farming accident sustained a crush injury to the left lower extremity 15 months before presentation. The patient had undergone multiple bony and soft tissues procedures, including local advancement flaps laterally over the ankle. She was employed as a schoolteacher. She had returned to work, standing most of the workday, but had reported excruciating pain limiting her daily and recreational activities. Physical exam revealed pain at both the subtalar and ankle joints. Motion was limited to five degrees of dorsiflexion and twenty degrees of plantar flexion with pain. Subtalar motion was absent with no active or passive inversion or eversion demonstrable.

Plain radiographs revealed significant posttraumatic ankle and subtalar arthrosis with evidence of collapse of the body of the talus into a varus position (Figs. 3 and 4). Initial treatment included AFO bracing and nonsteroidal medication without significant relief after 3 months. The decision to do a tibiotalocalcaneal arthrodesis was based on the pain at both the ankle and subtalar joints. A preoperative MRI confirmed the presence of diffuse AVN of the talus (Fig. 5). Despite significant involvement of the body of the talus, arthrodesis occurred at 12 weeks postoperatively (Figs. 6 and 7).

FIG. 3.
FIG. 3.:
Case 1: Preoperative AP and oblique x-ray.
FIG. 4.
FIG. 4.:
Case 1: Preoperative lateral x-ray.
FIG. 5.
FIG. 5.:
Case 1:(A) MRI lateral image: AVN of the talus. (B) MRI AP image: AVN of the talus.
FIG. 6.
FIG. 6.:
Case 1: Postoperative AP x-ray with IM nail.
FIG. 7.
FIG. 7.:
Case 1: Postoperative lateral x-ray with IM nail.

Ankle Arthrodesis

There are many, many techniques for tibio-talar arthrodesis described in the literature. The author's preferred methods of ankle arthrodesis with AVN of the talus use either a lateral or an antero-lateral exposure to the tibiotalar joint. The lateral exposure, which used a transfibular approach is the same as the technique described above for tibiotalocalcaneal arthrodesis, but with a shorter incision (less distal extension). Care should be taken to minimize soft tissue dissection around the talar head and neck, and to protect the blood supply to the talus as much as possible.

If the dissection can be accomplished through a single lateral incision, this will minimize soft tissue injury. If necessary, a second anteromedial incision can be made over the ankle joint if adequate exposure cannot otherwise be obtained. Again, full thickness flaps should be created. Thorough debridement of the opposing surfaces of the medial malleolus and talus enhances the fusion by providing another area for arthrodesis. Retention of the medial malleolus is important for stability of the arthrodesis because the medial malleolus may act as a buttress. 20 Removing the medial malleolus (cosmetically) reduces the thickness of the ankle, but may lead to longer healing times and an increased rate of nonunion. 21

The antero-lateral approach is a modification of the “mini-arthrotomy” technique described by Myerson. 22 This technique has the advantage of even more minimal dissection of the soft tissues, which enhances fusion. It is primarily appropriate for cases in which there is little or no deformity. A lamina spreader is required for exposure, which may also be aided by percutaneous release of the Achilles tendon with a #11 scalpel blade.

Regardless of which exposure technique is selected, the surfaces of the tibia and talus are prepared with hand or power instruments, preferably the former. This can be done with flat cuts, but the use of concentric curved surfaces is technically easier. These match the normal curve of the joint, thus having the advantage of less removal of bone, and allowing easier adjustment of position in dorsiflexion and plantarflexion. Once the surfaces are prepared, the talus should be inspected for any frankly necrotic or deeply sclerotic areas, which may inhibit union. Using a curette or rongeur, these should be debrided and packed with bone graft from one of a number of possible sites such as the fibula, the iliac crest, or (author's preference) the proximal tibia.

The desired position of the ankle is now evaluated. This position should be approximately neutral dorsiflexion/plantar flexion and neutral to five degrees of valgus. 1 Ideally, the talus should be slightly posterior to the anterior edge of the tibia. The position is verified by fluoroscopy. A 2.5 mm drill bit is used to perforate the bony surfaces at the arthrodesis site to encourage bleeding. This can also be accomplished with an osteotome. The reduction of the ankle joint can be held manually or two 0.062 K-wires can be placed prior to fixation. The arthrodesis is secured and compressed with large screws (preferably, a total of three screws). At least two of these are typically 6.5 mm, partially threaded, cancellous screws. They are placed percutaneously. The first screw placed is from superomedial on the tibia, directed into the lateral body of the talus, or conversely, from 180 degrees (i.e., from the lateral process of the talus [or sinus tarsi] into the medial metaphysis of the tibia). This is an easy screw to place, and allows immediate stabilization of the arthrodesis prior to placing the more difficult posterior screw. The second screw is placed from the posterior malleolus directed anteromedially into the head and neck of the talus as described by Holt et al. 13 This provides for compression at the arthrodesis site and for some posterior translation of the talus. The bone in the head and neck of the talus is less affected by avascular necrosis because of the distal to proximal blood supply of the talus. The third screw is then placed obliquely from medial or lateral between the talus and tibia. This can be crossed or parallel to the first screw. In small individuals, a 4.5 mm cortical screw placed from the talus into the cortex of the distal tibia offers the advantage of easier placement while achieving strong fixation. The stability at the arthrodesis site should is checked manually, and with the image intensifier as the process of fixation proceeds. The bone graft is applied before apposition of the surfaces, especially if replacing necrotic talus. The remaining bone graft is used to augment the fusion extra-articularly anteriorly, medially, and especially, laterally.

Closure and splinting are as described above under tibiotalocalcaneal arthrodesis.

Case:

A 48-year-old female fractured her ankle at 8 years old. The patient is an emergency room nurse. She began to develop symptoms 4 years prior to presentation. The patient stated the pain had limited her on a daily basis. Physical exam revealed pain and tenderness at the tibiotalar joint. Range of motion at the ankle was painful. It measured zero degrees of dorsiflexion and five degrees of plantar flexion. The subtalar joint range of motion was 15 degrees of inversion and five degrees of eversion but painless.

Plain radiographs revealed significant collapse of the talar body and eccentric wear of the tibiotalar joint with some anterior translation of the talus on the distal tibia (Figs. 8 and 9). The subtalar joint had mild osteoarthrosis. An MRI was completed. There was extensive AVN of the talus with collapse and cystic degeneration of the anterior tibial plafond (Fig. 10). The patient enacted lifestyle changes, began taking anti-inflammatory medication, and wore a posterior-shell AFO lined with plastazote for eight months without significant relief, at which time the an ankle arthrodesis was completed (Figs. 11 and 12). Arthrodesis occurred at 12 week postoperatively.

FIG. 8.
FIG. 8.:
Case 2: Preoperative AP and oblique x-ray.
FIG. 9.
FIG. 9.:
Case 2: Preoperative lateral x-ray.
FIG. 10.
FIG. 10.:
Case 2: MRI lateral image: AVN of the talus
FIG. 11.
FIG. 11.:
Case 2: Postoperative AP and oblique X-ray: ankle fusion.
FIG. 12.
FIG. 12.:
Case 2: Postoperative lateral image: ankle fusion.

Tibiocalcaneal Arthrodesis

The authors' preferred method of tibiocalcaneal arthrodesis in most patients with avascular necrosis of the talus entails the use of the retrograde nail as described above. After excision of the body of the talus, the arthrodesis surfaces are prepared and adjusted to perform arthrodesis of the talar neck and head to the anterior tibia. Once properly positioned, the retrograde nail is placed. Then the fixation of the talar head and neck to the anterior tibia is performed with screws from the posterior tibia placed directly anteriorly into the talar neck and head. The technical challenge is to place these around the nail.

Similar results can be achieved with screw fixation alone, which can be a preferable technique if there is severe osteopenia or osteoporosis of the calcaneus, or if there is bone loss of the calcaneus.

Once the ankle and subtalar joints are exposed the avascular talar body can be removed. A saw blade is used to cut the talus at the neck from lateral to medial. This also exposes the dorsal calcaneal surface. Again using the saw, the anterior surface of the distal tibia is flattened enough to provide good surface apposition with the talar remnant. The distal surface of the tibia is also resected with the saw perpendicular to the shaft of the tibia, and extended fully across the joint to include resection of the medial malleolus. The dorsal calcaneus is also trimmed as necessary, excising completely the middle and posterior facets to provide wide apposition with the surface of the distal tibia. Care should be taken not to disturb the calcaneocuboid joint. The surfaces should smoothly oppose. The position of the foot should be neutral plantar flexion/dorsiflexion and zero to five degrees of valgus. Rotation should match that of the opposite side as much as possible. The necessary shortening makes obvious the compromises of the positioning in this procedure.

If necessary, a second incision can be made over the anteromedial ankle joint. Prior to placement of the nail, the cancellous graft should be applied to the arthrodesis site. Surfaces of the arthrodesis site should be perforated with a drill or osteotome to encourage bleeding.

The neck of the talus is brought flush with the anterior tibia and can be manually held in position or by use of temporary K-wire fixation. Two screws, usually 4.5 mm cortical screws, are then placed from posterolateral to anteromedial around the intramedullary nail to fix the talar head and neck to the tibia. The remaining bone graft is placed at the arthrodesis site.

The wounds are closed over a 1/8-inch drain placed anteriorly. The deep layer is closed with 0 vicryl and the subcutaneous layer with 2–0 vicryl. Skin is closed with 3–0 nylon in a vertical mattress fashion. A bulky Jones dressing with posterior plaster splint and stirrups is applied.

Case:

This case demonstrates the surgical technique for this procedure using screw fixation. A 35-year-old female involved in a motor vehicle accident sustained multiple injuries including a left calcaneus fracture and right severely comminuted talar body fracture (Figs. 13 and 14). Because of the severe comminution and likelihood of AVN the decision was made to perform a primary tibiocalcaneal arthrodesis.

FIG. 13.
FIG. 13.:
Case 3: Preoperative CT scan: talar body fracture.
FIG. 14.
FIG. 14.:
Case 3: Preoperative CT scan: talar body fracture

The patient remained nonweightbearing bilaterally for three months. Postoperative radiographs revealed a solid fusion (Figs. 15 and 16). The patient complained of no pain in the foot or at the fusion site. She required a shoe lift for the subsequent leg length discrepancy.

FIG. 15.
FIG. 15.:
Case 3: Postoperative lateral x-ray: primary tibiocalcaneal fusion with talectomy.
FIG. 16.
FIG. 16.:
Case 3: Postoperative mortise x-ray: primary tibiocalcaneal fusion with talectomy.

COMPLICATIONS

There are several major complications that can occur after attempted arthrodesis in a patient with avascular necrosis of the talus. The most difficult is nonunion. Nonunion rates have been reported as high as 88%. 23 In 1994, Frey et al. reported on factors that may predispose to nonunion. 23 They reported eight of nine patients with AVN of the talus went onto nonunion. However, Kitoaka and Patzer found that 16 of 19 patients with AVN of the talus fused. 12 They recommended the maintenance of the talar body to decrease shortening and preserve the biomechanics of the foot. Possible salvage for nonunion of the ankle may include advancing the arthrodesis to include the subtalar joint or excision of the avascular talus and tibiocalcaneal arthrodesis.

A second major complication is malunion. This can create significant difficulties with ambulation and gait. Though most malunions can be treated with shoe modification or orthoses, it can lead to tissue breakdown or stress fracture due to abnormally high pressures. As little as two to four degrees of malunion can cause significantly increased pressure. 24 Varus malunion has been found to decrease the natural motion of the hindfoot and the a plantar-flexed malunion caused genu recurvatum. 19 The optimal position of neutral plantar flexion/dorsiflexion with neutral to five degrees of valgus and equal external rotation to the contralateral side should be the goal in all three types of arthrodesis.

Infection and soft tissue breakdown is also a major concern. Some authors have noted infection rates as high as 23% after ankle arthrodesis. 13 Superficial wound infections can be treated with oral antibiotics. Deep infections should be treated aggressively with repeat irrigation and debridement and intravenous antibiotics. Removal of the hardware and placement of antibiotic beads may be necessary with a staged revision arthrodesis. Early plastic surgery intervention is recommended as local or free flap coverage may be needed.

Intramedullary retrograde arthrodesis technique itself is associated with a high rate of complications. Barker et al. demonstrated an overall rate of 60% with the rate of major complications being about half, or 30%. 25 These included five tibiotalar nonunions and two subtalar nonunions. Minor complications included tibial stress reactions and stress fractures.

POSTOPERATIVE CARE

Patients undergoing all three of these procedures are managed with a similar postoperative protocol after these three arthrodesis techniques. The patient is placed into the bulky Jones dressing with a posterior splint and stirrup. They are kept as inpatients for 2 to 3 days for pain control and physical therapy. The first postoperative appointment is at approximately 2 weeks, at which time the dressing is removed. Depending upon the wound healing, the sutures are removed at 2 and 6 weeks, postoperatively. The patient is placed into a below-knee, nonweightbearing, fiberglass cast at 2 weeks postoperatively. The patient remains nonweightbearing for 8 weeks on average with a range of 6 to 12 weeks. This time is determined by clinical and radiographic evidence of the progression of bony union.

The patients begin partial weightbearing in the fiberglass cast and advance to full weightbearing over a period of approximately 2 weeks. At 12 weeks postoperatively, most of the patients are placed into a walking boot. They are weaned out of the walking boot between the 12th and 16th week postoperatively. Physical therapy is begun at the 12th week on a case-by-case basis for each patient.

Once out of the boot most patients will require the use of an orthoses. Most commonly this is a rocker-bottom sole, a solid ankle cushioned heel (SACH), or cushioned insert in their shoes. Mazur et al. found in their gait analysis that these decreased the impact at the arthrodesis site. 26

Lifestyle changes are recommended to the patients. These include a decrease in impact-loading exercises. Cycling, swimming, and elliptical trainer are encouraged.

A decrease in the amount of time standing at work (if possible) can help.

CONCERNS AND FUTURE OF THE TECHNIQUE

Techniques for arthrodesis after avascular necrosis have advanced to address both nonunion rates and shortening of the extremity. Early studies showed poor union rates. They have been significantly improved with advanced techniques, including compression fixation and intramedullary nailing. Union rates as high as 84% have been obtained. 12 Shortening of the extremity has been decreased by use of Ilizarov fixators and inclusion of the avascular talus in the arthrodesis (rather than excision) with encouraging rates of union. 7,12 Dennison et al. were able to equalize leg lengths with bone transport in tibiocalcaneal arthrodesis without nonunion. 12

Currently total ankle arthroplasty is considered either strictly contra-indicated (STAR prosthesis) or a very limited option (Agility Ankle) for treatment of arthrosis associated with avascular necrosis of the talus. The need for practical techniques for reconstruction by arthrodesis appears to continue into the foreseeable future.

REFERENCES

1. Blair H. Comminuted fractures and fracture dislocations of the body of the astragalus: operative treatment. Am J Surg 1943; 59:37–43.
2. Morris H, Hand W, Dunn A. The modified blair fusion for fractures of the talus. JBJS 1971; 53-A:1289–1297.
3. Lionberger D, Bishop J, Tullos H. The modified blair fusion. Foot and Ankle 1982; 3:60–62.
4. Albert E. Zur reshktion des kniegelenkes. Wien Med Press 1879; 20:705–708.
5. Myerson M, Alvarez R, Lam P. Tibiocalcaneal arthrodesis for the management of severe ankle and hindfoot deformities. Foot Ankle Intl 2000; 21( 8):643–650.
6. Mann R, Chou L. Tibiocalcaneal arthodesis. Foot and Ankle Intl 1995; 16( 7): 401–405.
7. Dennison M, Pool R, Simonis R, et al. Tibocalcaneal fusion for avascular necrosis of the talus. JBJS 2001; 83-B:199–203.
8. Russotti G, Johnson K, Cass J. Tibiotalocalcaneal arthodesis for arthritis and deformity of the hind part of the foot. JBJS 1988; 70-A:1304–1307.
9. Kile T, Donnelly R, Gehrke J, et al. Tibiotalocalcaneal arthrodesis with an intramedullary device. Foot and Ankle Intl 1994; 15( 12):669–673.
10. Moore T, Prince R, Pochatko D, et al. Retrograde intramedullary nailing for ankle arthrodesis. Foot Ankle Intl 1995; 16( 7):433–436.
11. Quill GE. Tibiocalcaneal and pantalar arthodesis. Foot and Ankle Clinics of North America 1996; 1:199–210.
12. Kitaoka H, Patzer G. Arthodesis for the treatment of arthrosis of the ankle and osteonecrosis of the talus. Journal of Bone and Joint Surgery 1998; 80-A:370–9.
13. Holt E, Hansen S, Mayo K, et al. Ankle arthodesis using internal screw fixation. Clin Orthopaedics and Related Research 1991; 268:21–28.
14. Mann R. Athrodesis of the foot and ankle. In:Surgery of the Foot and Ankle, 6th ed. Mosby, 1993.
15. Swanson T, Bray T, Holmes G. Fractures of the talar neck. JBJS 1992; 74-A:544–551.
16. Flock TJ, Ishikawa S, Heckt PJ, et al. Heel anatomy for retrograde tibiocalcaneal roddings: a roentgenographic and anatomic analysis. Foot and Ankle Intl 1997; 18( 4):233–5.
17. Pochatko D, Smith J, Phillips R, et al. Anatomic structures at risk: combined subtalar and ankle arthrodesis with a retrograde intrameduallary rod. Foot and Ankle Intl 1995; 16( 9):542–547.
18. McGarvery W, Trevino S, Baxter D, et al. Tibiotalocalcaneal arthrodesis: anatomic and technical considerations. Foot and Ankle Intl 1998; 19( 6):363–369.
19. Buck P, Morrey B, Chao E. The optimum position of arthodesis of the ankle: a gait study of the knee and ankle. JBJS 1987; 69-A:1052–1062.
20. Mann R, VanManen J, Wapner K, et al. Ankle fusion. Clin Orthop 1991; 268:49–55.
21. Mann R, Rongstad K. Arthrodesis of the ankle: a critical analysis. Foot Ankle Intl 1998; 19( 1):3–9.
22. Paremain G, Miller S, Myerson M. Ankle arthrodesis: results after the miniarthrotomy technique. Foot and Ankle Intl 1996; 17( 5):247–252.
23. Frey C, Halikus N, Vu-Rose T, et al. A review of ankle arthodesis: predisposing factors to nonunion. Foot and Ankle Intl 1994; 15:581–584.
24. Papa J, Myerson M. Pantalar and tibiotalocalcaneal arthrodesis for post-traumatic osteoarthrosis of the ankle and hind foot. JBJS 1992; 74-A:1042–1049.
25. Barker H, Brodsky J, Stephenson K. Complictations following retrograde intrameduallry tibiocalcaneal arthrodesis. Presentation AOFAS Meeting Summer 2001, publication pending.
26. Mazur J, Schwartz E, Simon S. Ankle arthrodesis: long-term follow-up with gait analysis. JBJS 1979; 61-A:964.
Keywords:

avascular necrosis; talus; arthrodesis

© 2002 Lippincott Williams & Wilkins, Inc.