Triple Arthrodesis 

Updated: Sep 23, 2021
Author: Stephen M Schroeder, DPM, FACFAS; Chief Editor: Jeffrey D Thomson, MD 

Overview

Background

A triple arthrodesis is a procedure consisting of the surgical fusion of the talocalcaneal (TC), talonavicular (TN), and calcaneocuboid (CC) joints in the foot. The primary goals of a triple arthrodesis are to relieve pain from arthritic, deformed, or unstable joints. Other important goals are the correction of deformity and the creation of a stable, balanced plantigrade foot for ambulation.

Edwin W Ryerson first described triple arthrodesis in 1923 as a fusion of the TC, TN, and CC joints.[1] The aim was to create a well-aligned, plantigrade, and stable foot that would allow patients with paralytic or deforming conditions to function better. The most common indications were to correct lower-extremity deformities in children resulting from poliomyelitis, cerebral palsy, Charcot-Marie-Tooth disease, clubfoot, or tuberculosis.

The original procedures were performed by removing large blocks of subchondral bone and correcting the angular deformities by inserting or removing wedges. The corrections were maintained by casting that often required later manipulation for loss of position. Kirschner wires (K-wires), Steinmann pins, and staples were used over time to hold the corrections in place but are now not as common.

Internal fixation with various compression screws using the Arbeitsgemeinschaft für Osteosynthesefragen (AO) technique and specially designed plating systems has become the standard of care.

For patient education resources, see the Foot, Ankle, Knee, and Hip Center and Arthritis Center, as well as Rheumatoid Arthritis.

Indications

Triple arthrodesis should be considered a salvage procedure and should be employed only after other conservative treatment modalities have been exhausted. The primary goals are to abolish pain, correct underlying deformity, and restore a stable platform for ambulation. In conditions where a lesser fusion or soft-tissue procedure will suffice, triple arthrodesis should not be used, because of the potential long-term complications associated with it. The primary indications for the procedure are as follows[2] :

  • Valgus foot deformities that cannot be adequately braced
  • Collapsing pes planovalgus deformity
  • Advanced tibialis posterior tendon dysfunction
  • Degenerative arthritis (eg, degenerative joint disease [DJD])
  • Posttraumatic arthritis
  • Chronic pain
  • Varus foot deformities that cannot be adequately braced
  • Cavus and cavovarus [3]
  • Talipes equinovarus
  • Joint instability
  • Neuromuscular disease

The use of triple arthrodesis to treat Mueller-Weiss disease has also been described.[4]

Contraindications

Contraindications for triple arthrodesis include conditions that can be adequately corrected and maintained via external bracing, soft-tissue procedures, tendon balancing, or lesser fusions. Chronic smoking is a relative contraindication because of the associated high incidence of nonunion.[5]

Technical Considerations

Anatomy

The bony anatomy consists of the talus, the calcaneus, the cuboid, and the navicular. The talus and the calcaneus make up the TC joint (also referred to as the subtalar joint). Its articular portion is composed of the more important posterior facets of the talus and calcaneus and the smaller anterior and middle facets. The anterior talofibular, posterior talofibular, calcaneofibular, deltoid, and interosseous TC ligaments stabilize it.

Subtalar motion is triplanar and is described appropriately as pronation (dorsiflexion, eversion, and external rotation) and supination (plantarflexion, inversion, and internal rotation). Clinically, however, most motion takes place in the frontal plane and is seen as heel eversion and inversion. Although normal range-of-motion (ROM) values are difficult to measure, a practical rule of thumb is 30° of total motion with approximately 10° of inversion and 20° of eversion.

The sinus tarsi is a tunnellike structure extending from distal lateral to posterior medial in the rearfoot. It is formed dorsally by the concavity in the neck of the talus and plantarly by the sulcus between the posterior facet and sustentaculum tali of the calcaneus. This structure is widest laterally and contains the bifurcate, cervical, and interosseous ligaments. It is filled by a fatty plug known as the Hoke tonsil and serves as the origin of the extensor digitorum brevis (EDB).

The head of the talus and the navicular constitute the TN joint. This is a condylar joint. The head of the talus is convex, and the corresponding surface of the navicular is concave. This is an important spatial relation to understand because the navicular forms a lip around a portion of the talar head, making it difficult to access the joint fully and remove adequate amounts of cartilage.

Normally, during stance phase, the calcaneus everts, and the talus plantarflexes and internally rotates. This action produces a relative dorsiflexion, eversion, and abduction of the navicular, which subsequently translates that motion to the forefoot. In excessive or pathologic cases, this presents as medial arch collapse with forefoot abduction. The opposite takes place with weightbearing TC joint supination.

The anterior articular portion of the calcaneus and the cuboid make up the CC joint. This is often the first joint resected during a triple arthrodesis and is the most easily accessible of the three joints. Directly superior to the joint is the EDB muscle belly, and lateral to it are the peroneal tendons.

The sural nerve courses along the lateral side of the foot, and the superficial peroneal nerve takes a more dorsal lateral position. It should be noted that there is significant anatomic variation of the sural nerve, and care must be exercised in making the incision. The lateral incision is placed between these two nerves. The saphenous nerve and vein enter the foot on the dorsal medial aspect. A medial incision is also made and is usually located in line with and just plantar to these structures.

For more information about the relevant anatomy, see Foot Bone Anatomy and Ankle Joint Anatomy.

Procedural planning

Presentations in the clinic can vary, depending on the underlying pathology. A common feature of patients is the development of DJD. Conditions that produce an improperly functioning, unstable foot that leads to DJD are the main indications for surgical treatment.

TC joint arthritis usually manifests as pain located anterior to the distal tip of the fibula in the region of the sinus tarsi. The pain is exacerbated with forced inversion and eversion of the heel. In advanced cases, crepitation is noted with forced ROM. Similar findings can be seen in the CC and TN joints. Pain is usually elicited with periarticular palpation.

Depending on the underlying pathology, the patient may present with a varus or valgus deformity. Posttraumatic arthritis often presents with a rectus foot and complaints consistent with DJD of the TC joint. It commonly occurs after calcaneal fractures with posterior facet involvement.

Depending on the severity of the fracture, the heel can be shortened, can be widened, and can have an uneven lateral wall with bony prominences (see the images below). These findings are typically seen in lateral-wall blowout fractures that do not undergo open reduction with internal fixation (ORIF). Similar fractures with inadequate ORIF, or inadequate reduction, leaving a varus or valgus deformity, can also be seen in these cases.

CT scan of calcaneal fracture shows prominent late CT scan of calcaneal fracture shows prominent lateral wall with heel rotated into varus.
Lateral wall blowout fracture with comminution. No Lateral wall blowout fracture with comminution. Note shortening and widening of heel. If left untreated, heel would remain in varus with uneven lateral wall and bony prominence that could become irritated.
Lateral wall blowout fracture with comminution. No Lateral wall blowout fracture with comminution. Note shortening and widening of heel. If left untreated, heel would remain in varus with uneven lateral wall and bony prominence that could become irritated.
Relatively mild calcaneal fracture still exhibitin Relatively mild calcaneal fracture still exhibiting shortening and widening.

Valgus deformities are commonly seen in collapsing pes planovalgus, late-stage tibialis posterior tendon dysfunction, tarsal coalition, and some neuromuscular conditions. They are easy to identify, especially in the latter stages of the deformity, and present with a heel in valgus, an abducted forefoot, and a medial arch that is typically collapsed (see the images below).

Medial arch collapse associated with valgus deform Medial arch collapse associated with valgus deformity.
Valgus foot deformity with medial dislocation of t Valgus foot deformity with medial dislocation of talar head. Note abducted forefoot and head of talus rotated medially on navicular.
Valgus foot deformity with medial dislocation of t Valgus foot deformity with medial dislocation of talar head. Note abducted forefoot and head of talus rotated medially on navicular.
Clinical view of valgus foot deformity with abduct Clinical view of valgus foot deformity with abducted forefoot and collapsed medial arch.
Valgus deformity with medial talar rotation that i Valgus deformity with medial talar rotation that is so severe that patient bears weight on head of talus.

Varus foot deformities are seen in cavus foot types, cavovarus foot types, talipes equinovarus, and some neuromuscular conditions. The most common neuromuscular condition presenting with a varus deformity is Charcot-Marie-Tooth disease (see the images below). This deformity is also fairly easy to identify. The patient will have a heel that is in a varus position, an adducted forefoot, a higher-than-normal arch, and ankles that are storklike.

Varus foot deformity in patient with Charcot-Marie Varus foot deformity in patient with Charcot-Marie-Tooth disease.
Cavovarus deformity with high-arched foot. Note ha Cavovarus deformity with high-arched foot. Note hammertoe deformity to all 5 digits common to this condition.
Triple arthrodesis. Cavovarus with high-arched foo Triple arthrodesis. Cavovarus with high-arched foot, hammertoe deformity, adducted forefoot, and severely plantarflexed first metatarsal.
Cavovarus with high-arched foot, hammertoe deformi Cavovarus with high-arched foot, hammertoe deformity, adducted forefoot, and severely plantarflexed first metatarsal.

Outcomes

Outcomes are typically good, with high union rates of the TC and CC joints. The TN joint has the highest incidence of nonunion; however, the nonunion rate decreases with better understanding of the procedure and stable fixation. Degenerative changes at the unfused distal and proximal joints are still a long-term complication, but this is true with any fusion procedure. A study examining 400 triple arthrodesis procedures found less-than-perfect results in 24.5% of patients.

A period as long as 10 months is required for the patient to become pain-free. Return to high-impact activity is not a given. Lower-impact activities like walking, cycling, and swimming should be obtainable goals postoperatively.

 

Periprocedural Care

Preprocedural Planning

Laboratory studies

If the underlying pathology is obvious and the pain is generated from degenerative joint disease (DJD), no specific laboratory tests are warranted except for standard preoperative studies. When the underlying diagnosis is not as clear, however, arthritis panels may be ordered to rule out inflammatory arthropathies or gout. If Charcot arthropathy is suspected, imaging studies or bone biopsies are the studies of choice. Joint-fluid analysis can also be performed if gout or an infectious process is suspected.

Imaging studies

Standard anteroposterior (AP), lateral, and oblique weightbearing radiographs are obtained as part of the initial workup. In severe cases, ankle, weightbearing AP, and mortise views should be included.

The three joints in question—that is, the talocalcaneal (TC) joint (also referred to as the subtalar joint), the talonavicular (TN) joint, and the calcaneocuboid (CC) joint—are examined for degenerative changes manifested by joint-space narrowing, subchondral sclerosis, cyst formation, and osteophytic projection.

Osteophytes are easily identified at the TN and CC joints on the lateral and oblique views (see the image below).

Osteophytes and degenerative joint disease easily Osteophytes and degenerative joint disease easily seen at talonavicular, calcaneocuboid, and talocalcaneal (subtalar) joints.

The AP view reveals joint-space narrowing and abduction (common in valgus deformity) or adduction (common in varus deformity) of the forefoot (see the first image below). One can also appreciate the amount of uncovering of the articular surface on the talar head that is rotated medially from the concave articular surface of the navicular. More than 7° of displacement is considered abnormal and is commonly found in a valgus deformity with abduction of the forefoot (see the second image below).

Anteroposterior view depicting talonavicular and c Anteroposterior view depicting talonavicular and calcaneocuboid joints.
Articular surface on talar head rotated medially f Articular surface on talar head rotated medially from concave articular surface of navicular. More than 7° of displacement is considered abnormal and is commonly found in valgus deformity with abduction of forefoot.

The lateral view shows arch height. A low or collapsed arch indicates a valgus deformity, and a high arch indicates a varus or cavovarus deformity.

A useful adjunctive radiographic view is the Harris-Beath projection, which is taken with weightbearing, with the beam directed toward the posterior heel. Three views are shot, with the first angled 10° above the level of the declination angle of the posterior facet, the second angled at the same level, and the third angled 10° below. This allows the examiner to see the posterior facet joint space for pathology, as well as the amount of varus or valgus deformity in the rearfoot relative to the tibia (see the image below).

Harris-Beath projection allowing visualization of Harris-Beath projection allowing visualization of posterior facet of talocalcaneal (subtalar) joint and varus/valgus rotation.

Another adjunctive radiographic study is a standing full-length view of the legs. This is done to evaluate the mechanical axis of the tibia to the ground in patients with excessive genu varum. It becomes important because the foot must be fused in a position to accommodate these angles.[6]  An example of this is a patient with 10° of tibia vara. The TC joint must be fused in at least 10° of valgus (rearfoot relative to tibia) in order to position the foot perpendicular to the ground. Fusing the foot in a varus position often leads to complications and should be avoided.

Magnetic resonance imaging (MRI) and computed tomography (CT) are rarely performed as part of a workup for triple arthrodesis. MRI can be useful, however, if avascular necrosis of the talus or navicular is suspected. It can also be helpful in identifying the extent of an infectious process or Charcot arthropathy.

Important normal joint angles to keep in mind when examining imaging study findings are as follows:

  • Lateral view (see the first image below) - TC angle of 25-50°; talus, first metatarsal angle of 0°; calcaneal inclination angle of 20-25°
  • AP view (see the second image below) - TC angle of 15-50°; talus, first metatarsal angle of 0°; degree of talar head rotation less than 7° from the navicular
Lateral view demonstrating talocalcaneal angle (ye Lateral view demonstrating talocalcaneal angle (yellow angle marker), talus first metatarsal angle (black angle marker), and calcaneal inclination angle (red angle marker).
Anteroposterior view demonstrating talocalcaneal a Anteroposterior view demonstrating talocalcaneal angle (black angle marker), talus first metatarsal angle (red angle marker), and degree of talar head rotation from navicular (yellow marker).

Other tests

Cavovarus deformities in the rear foot can result from a forefoot cavus deformity or an isolated plantarflexed first metatarsal. In these situations, the rearfoot compensates by rotating into varus. The Coleman block test is used to determine if the deformity is in the forefoot or hindfoot and to see if the deformity is reducible.

The forefoot is "off-weighted" by placing a block under the heel so that the rearfoot no longer has to compensate for a forefoot cavus. If the rearfoot normalizes and becomes perpendicular to the ground, the deformity lies in the forefoot and should be addressed as part of the procedure. In rigid cavovarus foot, the deformity does not reduce.

Diagnostic procedures

As mentioned above, if Charcot arthropathy is suspected, imaging modalities or bone biopsies are the studies of choice.

One of the most reliable office procedures for isolating joint pain from other pain generators is a local intra-articular anesthetic block. Relief of pain after injection confirms the location of the pain generator. Care must be taken to inject only into the joint, so that surrounding structures do not become anesthetized. TC joint injections are performed through the sinus tarsi. The sinus tarsi is palpated on the lateral aspect of the foot, and a 1.5-in. needle is directed toward a point just inferior to the sustentaculum tali on the medial side of the foot (see the images below).

Talocalcaneal (subtalar) joint injection via sinus Talocalcaneal (subtalar) joint injection via sinus tarsi.
Talocalcaneal (subtalar) joint injection via sinus Talocalcaneal (subtalar) joint injection via sinus tarsi.

The TN and CC joints may be more difficult to inject, especially when osteophytes are present, and may require fluoroscopic or ultrasonographic guidance may be required.

Patient Preparation

The patient is placed supine on the operating table, and either general or spinal anesthesia is administered. A popliteal block should be considered to help with postoperative pain control. A proximal thigh tourniquet is applied, and a bump is placed under the ipsilateral hip. This positioning internally rotates the foot and allows easier access for the lateral incision and the ipsilateral iliac crest should autogenous bone graft be needed.

Monitoring & Follow-up

The patient remains nonweightbearing (NWB) for 6-8 weeks and is then reevaluated. At that time, the patient is allowed to bear weight in a removable walker boot if no complications have arisen and trabeculation is noted on radiographs. Additional films are obtained at approximately 12 weeks and evaluated for consolidation. If stable fusion is observed, the patient is taken out of the cast boot and allowed to progress to normal shoes. The patient should undergo physical therapy for continued range-of-motion (ROM) and strength training.

Delayed union, especially at the TN joint, is not uncommon and may require further immobilization and NWB.[7]

 

Technique

Approach Considerations

As with most cases, nonsurgical measures should be exhausted before surgical intervention is considered. This is especially true in planning a salvage procedure like a triple arthrodesis. Conservative treatment consists of physical therapy, strapping and tapping, nonsteroidal anti-inflammatory drugs (NSAIDs), steroid injections, and bracing.

Most triple arthrodesis procedures are performed by removing all of the cartilage from the three joints involved—that is, the talocalcaneal (TC) joint (also referred to as the subtalar joint), the talonavicular (TN) joint, and the calcaneocuboid (CC) joint—and fusing them with bone-to-bone contact. Positional corrections can usually be achieved by rotating the foot along the natural contours of the joint surfaces prior to fusion. In cases of severe deformity, however, wedges of bone may have to be removed from or added to the joints to achieve the desired correction.[2, 6, 8, 9, 10, 11, 12, 13, 14]

One area of controversy regarding this procedure has to do with using external fixation devices. Proponents would argue that this is a stable fixation method that allows patients to ambulate with partial to full weightbearing on the operative side. Others would argue that the risk of pin-tract infections is high and could be disastrous to the procedure's outcome. A study that assessed 87 patients using a ring-style external fixation device reported a 97% fusion rate at 6-8 weeks, with a 36% rate of superficial pin-site infections.[14]

Orthobiologics play a growing role in augmenting these procedures. Autologous bone grafting is still the product of choice for filling voids; however, it is associated with a certain degree of morbidity. Allograft bone and other orthobiologic materials are safe and effective alternatives that reduce risks to the patient.

The double arthrodesis has gained popularity over the last few years and involves fusion of the TN and TC joints only.[15, 16] It can be done through a single medial incision, preserves a nonarthritic CC joint, maintains the length of the lateral column, and has been shown to be a reliable method for correcting planovalgus deformity.[17] It is especially beneficial in cases where concern exists for lateral incision wound breakdown, as with compromised skin from previous trauma or a severe valgus deformity.[7, 18, 19, 17]

Arthroscopic arthrodesis is an accepted technique for the ankle but has not been as commonly reported for multiple hindfoot joints. A case series review by Jagodzinski et al found that arthroscopic double and triple arthrodeses appear to be feasible salvage options for pain and deformity, though late adjacent joint pain and arthrosis may develop.[20]  Various technical approaches have been described.[21] Arthroscopic triple arthrodesis may be more commonly performed in the future.[22]

Fusion of Talocalcaneal (Subtalar), Talonavicular, and Calcaneocuboid Joints

With the patient properly positioned (see Periprocedural Care, Patient Preparation), a lateral incision is made from just inferior to the distal tip of the lateral malleolus to the base of the fourth metatarsal (see the images below). The TC joint, the CC joint, and the lateral portion of the TN joint are thereby exposed. Care is taken to avoid branches of the sural and superficial peroneal nerves running just inferior and superior to the incision. This approach follows a plane between the two nerves, but small branches may enter the area and should be avoided if possible.

Triple arthrodesis. Lateral incision is made from Triple arthrodesis. Lateral incision is made from just inferior to distal tip of lateral malleolus to base of fourth metatarsal. This allows exposure to talocalcaneal (subtalar) joint, calcaneocuboid joint, and lateral portion of talonavicular joint. Care is taken to avoid branches of sural and superficial peroneal nerves running just inferior and superior to incision. This approach follows plane between nerves, but small branches may enter area and should be avoided if possible.
Triple arthrodesis. Anatomy of lateral incision: ( Triple arthrodesis. Anatomy of lateral incision: (A) lateral incision, (B) lateral malleolus, (C) base of fourth metatarsal, (D) base of fifth metatarsal, (E) peroneal tendons, (F) sural nerve, (G) intermediate dorsal cutaneous nerve.

The deep fascia is visualized through the entire course of the incision, and the extensor digitorum brevis (EDB) muscle belly is identified. An L-shaped incision is made through the deep fascia traveling along the course of the EDB insertion and then distally across the CC joint (see the image below). This releases the insertion of the EDB, allows access to the CC joint, and gives exposure to the sinus tarsi and the Hoke tonsil.

Triple arthrodesis. Deep structures encountered th Triple arthrodesis. Deep structures encountered through lateral incision: (A) Hoke tonsil before removal, (B) L-incision along insertion of extensor digitorum brevis (EDB) and across calcaneocuboid joint, (C) deep fascia over EDB.

The EDB muscle belly is flapped distally, starting at its proximal lateral margin, giving excellent exposure to the CC joint and allowing eventual exposure to the lateral TN joint.

The Hoke tonsil is next evacuated by carefully following the contours of the calcaneus with a No. 15 blade, beginning at the anterior process (see the image below).

Triple arthrodesis. (A) Extensor digitorum brevis Triple arthrodesis. (A) Extensor digitorum brevis elevated to expose (B) calcaneocuboid joint. (C) Hoke tonsil.

Care should be taken to identify and protect the peroneal tendons. All of the contents of the sinus tarsi should be removed, including the interosseous ligament, to gain exposure to the anterior portion of the TC joint.

A laminar spreader is placed into the sinus tarsi and used to open the TC joint, vertically separating the talus from the calcaneus. Transection of the calcaneofibular (CF) ligament may become necessary in cases where the joint remains tight and adequate exposure is not achieved. Articular cartilage is removed from the anterior, middle, and posterior facets by scraping with a curette or stripping with an osteotome.

The remaining subchondral bone is then fenestrated by using a 0.062-in. Kirschner wire (K-wire), a small drill bit, or a power bur. This allows vascular ingrowth through the subchondral plate and excellent bone preparation for fusion. Another method for penetrating the subchondral bone is to use a small osteotome or gouge to shingle the articular surface.

Attention is next directed to the CC joint, where the cartilage is denuded, leaving only subchondral bone. The surfaces are fenestrated in the fashion described above. Care should be taken to leave as much bone as possible at this joint, especially in valgus deformities, because lateral column length is important for correction. The lateral border of the TN joint can be reached after the CC joint is prepared by dissecting directly medially.

A capsulotomy is performed, and the laminar spreader is once again used to separate the articular surfaces. Any cartilage that can be removed through this incision should be before starting the medial approach.

A medial incision is made, beginning just anterior to the distal tip of the medial malleolus and extending dorsomedially toward the naviculocuneiform joint (see the images below). It lies between the anterior and posterior tibial tendons. The saphenous vein and nerve are typically located slightly dorsal to the incision and should be carefully retracted away during the dissection.

Triple arthrodesis. Medial incision is made beginn Triple arthrodesis. Medial incision is made beginning just anterior to distal tip of medial malleolus extending dorsomedially to naviculocuneiform joint. It lies between anterior and posterior tibial tendons. Saphenous vein and nerve are typically located slightly dorsal to incision and should be carefully retracted away during dissection.
Triple arthrodesis. Anatomy of medial incision: (A Triple arthrodesis. Anatomy of medial incision: (A) medial incision, (B) medial malleolus, (C) posterior tibial tendon, (D) tibialis anterior tendon, (E) saphenous vein.

A capsulotomy of the TN joint is performed in line with the skin incision, and periosteal flaps are created to expose the articular surface. A laminar spreader is inserted for exposure, and the cartilage is removed. The articular surface of the navicular is usually deeply concave, making cartilage excision difficult. Care must be taken to ensure that the entire surface is properly denuded in order to avoid healing problems. Osteophytes and a large medial tubercle on the navicular can be removed, if present.

Next, the foot is manipulated into the corrected position, and bone-on-bone contact at each joint is confirmed. Larger deformities may require that wedges be removed for optimal correction. Small gaps in joints can be filled with bone graft to help ensure solid union.

Once it has been established that the foot will reduce properly, it is temporarily fixated. The TC joint should be placed in about 4° of valgus relative to the ground. It is extremely important to not leave the hindfoot in varus; doing so will most certainly lead to postoperative complications. A helpful thought to keep in mind during this procedure is "Thou shalt not varus!" The forefoot is then aligned plantigrade to the floor.

Fixation techniques vary and often depend on the surgeon's preference.The TC joint should be fixated with a cannulated 6.5 or larger screw, which can be placed from the posterior plantar portion of the calcaneus into the body of the talus or from the neck of the talus into the body of the calcaneus (see the images below). Care should be taken not to disrupt nutrient arteries entering the neck of the talus if the latter approach is used.

Triple arthrodesis. Lateral view showing talocalca Triple arthrodesis. Lateral view showing talocalcaneal (subtalar) joint arthrodesis with 7.3 cannulated screw going from talus to calcaneus.
Triple arthrodesis. Lateral view showing talocalca Triple arthrodesis. Lateral view showing talocalcaneal (subtalar) joint arthrodesis using a 7.0 cannulated screw from calcaneus into talus.

Headless screws are useful with this technique, in that there is less chance of impingement on the tibia during dorsiflexion of the ankle joint. This can also be a timesaver because the area is highly accessible after the TN joint has been exposed. A secondary point of fixation is used if there is concern for rotational instability.

The TN and CC joints can be fixed with either staples or screws. If staples are used, at least two are placed in each joint, directed at 90° angles to each other. The use of compression staples and locking compression plates has greatly enhanced this technique and should be considered over the use of antiquated standard staples.

The technique preferred by the authors is to use two or three 4.0-4.5 cannulated screws placed parallel to each other in the TN and CC joints and to use a single 7.0-7.3 cannulated screw in the TC joint (see the image below). This technique works very well and saves time because the guide pins are used as temporary fixation.

Triple arthrodesis. Subchondral bone in joint with Triple arthrodesis. Subchondral bone in joint with degenerative joint disease can be very sclerotic and hard. It may be wise to extend guide hole from near cortex in navicular all the way through talonavicular joint and into talus, even when using cannulated screws that are self-drilling and self-tapping. Corkscrew-appearing hardware represents threads from cannulated screw that delaminated off implant during attempt to cut through subchondral bone in talar head.

Once the pins are in place, the corrected position is verified with fluoroscopy, and the screws are easily placed over the guide pins. Headless screws should be considered at the surgeon’s discretion. Two- or four-hole locking compression-style plates have also been used at the CC[23] and TN joints, providing excellent stability, compression, and time savings.

Hardware placement is verified with fluoroscopy, and residual gaps in joints, including the sinus tarsi, are filled with bone graft. The surgical sites are closed in layers, with care taken to repair the CF ligament and the insertion of the EDB. A lateral drain should be used to help prevent hematoma formation, especially when large portions of bone are resected.

If a preoperative block was not performed, an ankle block with 0.5% plain bupivacaine is performed to help decrease postoperative pain. Finally, a Jones-style compression dressing is applied with a posterior splint before deflation of the tourniquet.

Postoperative Care

Patients are usually kept overnight in the hospital for observation, pain control, and intravenous (IV) antibiotics. Anticoagulation therapy is started if deemed necessary.

After discharge, patients are instructed to spend at least the first 5 days with their foot elevated above their heart in order to control edema and pain. The patients are seen within 1 week for a dressing change, and a short leg cast is applied if the edema is controlled. Sutures are removed after 2 weeks, and the patient is placed back into a nonweightbearing (NWB) cast. The authors have also used external electric stimulation from postoperative day 1 on in higher-risk patients with good success, and the benefits of this approach have been confirmed by other authors.[24]

Complications

Because of the complex nature of the procedure and the various disease states being treated, complications after triple arthrodesis are relatively common. The following are the ones most frequently encountered.

Nonunion/malunion

As with any type of arthrodesis, nonunion or malunion is a potential complication.[25] In the case of the triple arthrodesis, the TN joint is the most common site of nonunion, with most studies reporting rates in the range of 5-10%.

In a retrospective radiographic review of 157 primary triple arthrodeses performed on 152 patients in one health maintenance organization, Klassen et al reported an overall nonunion rate of 29.9%.[26] With respect to the individual joints, the nonunion rate for the TN joint was 20.4%, that for the CC joint was 17.2%, and that for the TC joint was 8.9%.

The occurrence of nonunion or malunion is probably related to poor preparation of the joint surfaces, which are difficult to expose, especially if only a single lateral incision is used. Adding a second medial incision provides much better access to the joint and allows a more aggressive capsule release as well as easier distraction and better exposure for complete cartilage removal. A cadaveric study by Bono showed that only 38% of the cartilage from the TN joint was successfully removed via a lateral incision alone.[11]

Degenerative joint disease

A properly functioning foot goes through a multitude of movements with each phase of the gait cycle. A high degree of these movements takes place at the TC, TN, and CC joints. Most foot pronation and supination occurs around these joints. Once the three joints are fused, a large amount of stress is transferred to the joints immediately proximal and distal. Midfoot degenerative joint disease (DJD), or osteoarthritis, can develop with time.

An important intraoperative consideration is foot position. Excessive varus or valgus alignment of the rearfoot or forefoot can accelerate the onset of DJD.[18] A study by Aarts et al, in which 48 patients (55 feet) who underwent triple arthrodesis were followed for 7.5 years, found that triple arthrodesis per se did not lead to major osteoarthritis of the ankle, provided that adequate alignment of the hindfoot was achieved.[27]

A subsequent study from the same institution, aimed at determining whether malalignment after triple arthrodesis leads to a higher grade of osteoarthritis at long-term follow-up, evaluated 40 feet in 35 patients at 15 years after surgery.[28] The authors did not find malalignment after triple arthrodesis to result in a higher grade of osteoarthritis of the ankle joint in the long term.

Delayed wound healing

Many of these patients are elderly or debilitated from an underlying disease process that requires long-term steroid therapy. These issues can lead to delayed wound healing, most commonly seen as a mild dehiscence at the edges of the incision. Excessive postoperative edema can also delay healing. A rare situation that can cause large amounts of skin slough is placing the lateral tissues on stretch after reducing a large valgus deformity. This is a good indication for an isolated TN-TC arthrodesis through a medial approach if there are no arthritic changes seen at the CC joint.[19]

An important point that must also be appreciated is the relatively small amount of subcutaneous and fatty tissue in the foot. Dissection should be meticulous, with delicate handling of tissues, and healthy full-thickness skin flaps must be maintained..

Nerve injury

Both the lateral incision and the medial incision are placed close to underlying nerves.

The lateral incision lies between the sural and the superficial peroneal nerves. Small branches from each may be transected during the procedure. The intermediate dorsal cutaneous nerve, which is an extension of the superficial peroneal nerve, is located very close to the distal portion of this incision. Variations of these nerves do exist and can cross the path of the standard lateral incision; thus, careful dissection is warranted.

The medial incision is located in proximity to the saphenous nerve as well as to the medial dorsal cutaneous nerve at the distal margin of the wound.

Entrapments within surgical scar tissue can take place in the postoperative period; however, painful neuromas rarely occur. When they do happen, standard conservative measures with appropriate medications, injections, and physical therapy should be employed. If these measures fail, surgical neurolysis or proximal neurectomy with implantation into muscle is performed.

Avascular necrosis

Avascular necrosis is a rare complication but has been reported.[12] The predominant bone affected is the talus. In most instances, it results from disruption of the blood supply in the course of accessing the TC joint, resection of a large portion of the talar head to increase correction of deformity, or excessive dissection of the talar neck during placement of a screw from the talus down into the calcaneus.

Lateral instability

Lateral instability occurs for two main reasons. The first is malposition of the rearfoot in varus leading to excessive lateral stress on the ankle joint postoperatively. The other is inherent to the procedure: For adequate exposure to the TC joint, it is often necessary to transect the CF ligament, and if this ligament does not heal properly, lateral ankle instability can result.

Stiff foot

Stiff foot is not so much a complication of the procedure as it is a result of the procedure. The motions of pronation and supination around the TC joint allow the foot to adapt over uneven terrain. When the TC joint is pronated, the entire foot becomes flexible. Conversely, when this joint is supinated, the entire foot becomes rigid. These motions are normal and allow for shock absorption and conformation to surface terrain when pronated and propulsion when supinated.

Once the three joints are fused, the foot becomes stiff and loses flexibility. This should be explained to the patient before surgery as something to expect postoperatively. Ankle motion is also affected. One report showed a 13% decrease in dorsiflexion and a 16% decrease in plantarflexion.[13]