CHAPTER 36 Triple Arthrodesis

OVERVIEW AND APPROACH

In a triple arthrodesis, the subtalar, talonavicular (TN), and calcaneocuboid (CC) joints are included in the surgical fusion. A trend emerging over the past few years has been to try to preserve as much movement as possible in the remaining joint(s) of the hindfoot yet to create a functional plantigrade foot. Although a more limited hindfoot procedure such as a TN-subtalar arthrodesis or a subtalar-CC arthrodesis can be performed, such procedures may not reliably correct deformity. Nonetheless, as discussed further on, these more limited approaches have a lot of merit if performed in the right patient and with careful technique.

The triple arthrodesis is an extremely reliable procedure for correction of hindfoot deformity and treatment of associated arthritis. Although the approach to the procedure may have evolved or even changed technically, over the decades this has remained a standard method for correction of severe deformity regardless of the etiology. A triple arthrodesis is performed if a simpler hindfoot arthrodesis will not be sufficient; indications include a severe flexible flatfoot deformity, a rigid flatfoot deformity, posttraumatic arthritis, severe tarsal coalition associated with arthritis or uncorrectable deformity of the subtalar and transverse tarsal joint, congenital and neuromuscular deformity, and inflammatory arthritis. I try not to overuse the triple arthrodesis in the setting of the flexible flatfoot because osteotomy combined with tendon transfer usually is sufficient for correction of flexible deformity and generally can be expected to maintain joint motion. On the other hand, because a triple arthrodesis is so reliable a procedure, the indications for a flatfoot reconstruction should not be extended in order to specifically avoid an arthrodesis, because motion is not always preserved anyway. When arthritis of the tarsometatarsal or naviculocuneiform joints is present and a triple arthrodesis needs to be performed, there is obviously a considerable amount of stress on the intervening open joint, which may ultimately require arthrodesis. Nonetheless, what I refer to as an “extended hindfoot arthrodesis” must at times be performed.

Posttraumatic arthritis generally follows a talus or calcaneus fracture, but for most patients with arthritis and deformity secondary to a calcaneus fracture, a subtalar rather than a triple arthrodesis is the procedure of choice. A triple arthrodesis usually is the preferred procedure after a talar neck fracture with malunion, particularly when a varus malunion associated with arthritis is present (Figure 36-1). In the presence of a middle facet tarsal coalition, a subtalar arthrodesis is sufficient, and a triple arthrodesis is preferred only in the setting of arthritis or deformity, which typically is associated with a naviculocuneiform coalition, and when the coalition is not resectable. In patients with inflammatory arthritis, caution is indicated in selecting an isolated TN fusion, even when this is the only involved hindfoot joint. An isolated TN arthrodesis is associated with a higher incidence of nonunion, and once this occurs, correction is far more difficult because of bone loss and erosion, even with a triple arthrodesis.

Figure 36-1 A and B, Malunion of a fracture of the neck of the talus treated with open reduction and internal fixation. The hindfoot was fixed in varus as a result of shortening of the medial column of the hindfoot. C and D, Correction was accomplished with a triple arthrodesis achieved by resecting a small wedge from the lateral aspect of the calcaneocuboid joint.

SURGICAL APPROACHES

Over the years, I have been performing more hindfoot arthrodesis procedures through a single medial incision. Initially, I identified correction of a severe fixed valgus deformity as the specific indication for use of this approach, to limit the risk of lateral wound complications occurring as the hindfoot position is corrected to neutral (when using a lateral incision). This rationale still holds; nevertheless, I have been very pleased with the ability to correct deformity and associated arthritis from a single medial incision. Although the medial approach to triple arthrodesis is discussed in more detail further on, the concept of use of a single incision to perform a hindfoot correction is important. As might be expected, the inclusion of the CC joint in the fusion in performing a triple arthrodesis from the medial approach is difficult. In my own experience, both anatomic observations and outcomes in clinical series have demonstrated that the CC joint can be exposed and included in the arthrodesis with this approach. Nonetheless, as supported by results with my frequent use of the medial approach to correct deformity, it is apparent that the CC joint does not always need to be included in the arthrodesis (Figure 36-2). In performing the more limited arthrodesis (subtalar and talonavicular), however, it is important to recognize the potential for inferior subluxation of the cuboid relative to the calcaneus. This subluxation will produce a fixed rotation of the transverse tarsal joint, causing pain under the cuboid and the base of the fifth metatarsal. A good example of this potential problem is presented in Figure 36-3: After a limited arthrodesis performed using a medial approach, intraoperative fluoroscopy revealed that the CC joint was inferiorly subluxated, demonstrated by pushing up from below the cuboid to correct the subluxation, and could be corrected only by including the CC joint in the arthrodesis. There are probably fewer indications for a limited lateral arthrodesis, such as a subtalar and calcaneocuboid arthrodesis, but when the correction can be obtained, it is well worth trying to leave the talonavicular joint untouched.

Figure 36-2 A and B, Weight-bearing radiographic appearance of a rigid flatfoot deformity. C and D, Treatment consisted of a double arthrodesis (talonavicular and subtalar) performed using a medial approach to the hindfoot.

Figure 36-3 A, Fluoroscopic image, obtained at revision surgery, demonstrating the alignment of the hindfoot after an attempted double arthrodesis (talonavicular and subtalar). Note the inferior subluxation of the calcaneocuboid joint. B, Subluxation was confirmed on opening the lateral aspect of the foot. C and D, Correction was accomplished by including the calcaneocuboid joint in the arthrodesis.

The Lateral Incision

The incision is made from the tip of the fibular extending distally down over the sinus tarsi toward the CC joint (Figure 36-4). On the inferior surface of the incision, the peroneal tendon sheath is identified, and the terminal branch of the sural nerve must be looked for more distally in the incision. Both the peroneal tendons and the sural nerve are retracted inferiorly, and the incision can be deepened down on the periosteum directly over the calcaneus. The incision is extended distally toward the CC joint and then further toward the base of the fourth metatarsal. In the terminal aspect of the incision, care must be taken to ensure that no branches of either the sural or lateral cutaneous branch of the superficial peroneal nerve are present. The retinaculum of the undersurface of the peroneal tendon sheath is stripped and elevated off the lateral wall of the calcaneus. I prefer to save the contents of the sinus tarsi, because in the event of a wound dehiscence, sufficient tissue is always present for covering the peroneal tendons. The soft tissues are elevated sharply off the floor of the sinus tarsi until the anterior aspect of the posterior facet of the subtalar joint is visualized.

Figure 36-4 Lateral incision for hindfoot arthrodesis. The incision is marked out from the tip of the fibula across the sinus tarsi.

The incision is deepened directly onto the periosteum along the CC joint, and a large periosteal elevator is used to strip the lateral aspect of the calcaneus and then the cuboid. The peroneal retinaculum is retracted inferiorly, and a knife blade is inserted directly into the CC joint and then manipulated dorsally to cut the cervical ligament. The knife blade is swept vertically through the CC joint and then is rotated dorsally across the bifurcate ligament and directly into the posterior facet with one maneuver. The cuboid bone should now be freely mobile, and the articular surface of the entire joint is denuded with a 2-cm flexible chisel, as well as with a rongeur and curette. Removal of more than 2 mm of bone and cartilage on either side of the joint is unnecessary. An important point here is that regardless of the type of deformity, a lateral bone wedge is not removed, and the position of the hindfoot is corrected with translation and rotation, not with resection of bone wedges. A laminar spreader is inserted into the CC articulation to check that all of the cartilage has been removed. Care must be taken to ensure that a minimal amount of bone is resected, to minimize any shortening of the lateral column.

A laminar spreader is inserted into the sinus tarsi, and when it is placed on stretch, the interosseous ligament is easily visualized and cut to gain access to the posterior aspect of the subtalar joint and the middle facet. A 1-cm flexible chisel is used to denude the articular surface of the posterior facet. As with the CC joint, minimal bone is removed. The posterior facet must be debrided down to bleeding, healthy subchondral bone (Figure 36-5). Care is taken with the debridement of the posteromedial corner of the joint, where the flexor hallucis longus tendon is at risk for injury from the chisel. Finally, the more medial aspect of the subtalar joint and the middle facet must be completely denuded, including the undersurface of the talus and the dorsal surface of the middle facet. Before the medial incision is made, the space between the navicular and the cuboid is debrided with a rongeur. This debridement adds another segment and bone surface to the fusion mass and converts the triple arthrodesis to a “quadruple arthrodesis” (Figure 36-6).

Figure 36-5 A, The subtalar joint is visible with insertion of a laminar spreader, which pushes the joint anteriorly. B, Debridement is performed using a flexible chisel. Note the protection of the peroneal tendons by means of a curved retractor placed behind the subtalar joint.

Figure 36-6 A and B, The local anatomy of the junction between the talus, navicular, cuboid, and calcaneus. The junction of these four bones is the fourth joint in a so-called quadruple arthrodesis.

The TN joint is clearly the most difficult of the three joints to visualize and to debride adequately. With either a varus or valgus deformity, the TN joint is only partly visible, but it must be distracted to permit visualization in its entirety. It may be tempting to approach the TN joint from the lateral incision, but only one third of the joint is visible from this incision, perhaps more if the hindfoot is fixed in varus. Of note, however, the TN joint is the one joint that will end up in nonunion if the joint debridement is not performed carefully. The medial incision is made medial to the anterior tibial tendon, extending from the ankle toward the medial cuneiform bone. The extensor retinaculum is incised, and the anterior tibial tendon is retracted laterally, exposing the deep subcutaneous tissue. Partially cutting into the extensor retinaculum and the medial edge of the anterior tibial tendon more distally may be necessary at times, because the tendon blends into the fibers of the retinaculum.

After the dissection, a retractor is inserted to pull aside the anterior tibial tendon and the medial soft tissues. The periosteum along the navicular bone is stripped, and then the TN joint is fully exposed with a curved periosteal elevator. Inserting an elevator directly into the joint to fully expose the head of the talus, followed by further stripping of the soft tissue dorsally and laterally, is useful. When a severe valgus deformity is corrected, pushing the midfoot into varus and then loosening the tension of the medial TN joint are helpful. I then cut around the medial joint from the outside in, through the remnant of the posterior tibial tendon and spring ligament into the TN joint. This step makes opening and distraction of the joint far easier. A smooth laminar spreader (Figure 36-7, A) or rongeur is inserted into the joint and then exchanged for a toothed laminar spreader to facilitate distraction of the joint. Another option to maximize visualization of the joint is to apply distraction using pins inserted through a laminar spreader through which distraction can be applied (see Figure 36-7, B). The entire joint is denuded of cartilage using a 1-cm flexible chisel. An important consideration with the navicular is that because this bone can be hard, it can fragment if not debrided gently. The same contour must be maintained with debridement of the talar head while a small flexible chisel is used. Presence of osteopenia increases the risk of injury with use of the laminar spreader, which may crush into the talus. At the completion of the joint debridement, surfaces should appose well, with maintenance of the overall joint contour. If bone is resected from either joint surface, the medial column of the foot will be shortened, followed by a varus malunion.

Figure 36-7 A, The talonavicular joint can be exposed by inserting a laminar spreader into the joint. B, Alternatively, pins can be inserted through a laminar spreader to distract the joint.

Once the joints have been adequately visualized and their surfaces debrided, the final preparation is accomplished with a 2-mm drill bit to thoroughly perforate each bone surface. This aspect of the procedure is particularly important when the bone is sclerotic, which often is the case with the navicular.

Reduction of Deformity and Fixation

The reduction maneuver of the hindfoot relative to the forefoot is critical. For most deformities, the hinge point is the TN joint; therefore this is the joint that I reduce and fix first. The foot is rotated around the axis of the TN joint, and as the forefoot is adducted, the first metatarsal is plantar flexed to correct the forefoot relative to the hindfoot (Figure 36-8). This maneuver is unsuccessful only when the subtalar joint is rigid and the calcaneus is laterally translated, in which case I fix the subtalar joint first. In the latter instance, then the TN joint may not line up perfectly, although clinically the forefoot alignment may appear to be corrected. For some very severe deformities that feature gross posterior subluxation of the subtalar joint, it is helpful to address this problem first by inserting a laminar spreader between the anterior process of the calcaneus and the lateral process of the talus. This maneuver forces the calcaneus forward, reducing the subtalar subluxation.