Jacob R. Zide and James W. Brodsky

Abstract

Combined ankle and subtalar joint arthritis, failed ankle arthroplasty, neuroarthropathic Charcot’s ankle collapse, talar osteonecrosis, and ankle and hindfoot deformity with bone loss are difficult problems to manage surgically. Combined tibiotalocalcaneal arthrodesis utilizing a compressing, retrograde, intramedullary (IM) nail fixation is a powerful technique for difficult reconstructions, even and especially when associated with significant bone loss. The IM nail device is a load-sharing device, and offers excellent bending stiffness and improved fusion rates, attributable to power of compression across both ankle and subtalar joints. This chapter outlines the technique for implantation and tips to obtain optimal results.

Keywords: ankle joint, subtalar joint, arthritis, tibiotalocalcaneal, ankle arthrodesis, subtalar arthrodesis, bone loss, avascular necrosis

53.1 Indications

• Concomitant ankle and subtalar arthritis (degenerative, post-traumatic, or inflammatory).

• Skin: previous incisions are noted so that they can either be incorporated into the surgical approach or be avoided altogether.

• Vascular: examination of pedal pulses is crucial. Weak or impalpable pulses should prompt further work-up with arterial studies (ABI and toe pressures) and/or vascular surgery consultation.

• Neurological: sensory examination with light touch is evaluated. It is important to be on the lookout for peripheral neuropathy (whether diabetic, idiopathic, or from another cause). If neuropathy is suspected, Semmes-Weinstein testing with a 5.07 monofilament should be performed along with consideration of neurology consultation.

• Motor: assessment of power about the ankle, especially as it pertains to the posterior tibialis and peroneals, is valuable since soft-tissue balancing may be required in order to correct varus/valgus deformity.

53.1.2 Radiographic Evaluation

• Standing X-ray evaluation with anteroposterior (AP), oblique, and lateral views of the foot and ankle should be performed.

• If there is an associated malalignment of the knee or tibia, consider longstanding radiograph of the lower extremities to assess.

• Computed tomography (CT) scan is obtained to fully evaluate the intra-articular deformity and any associated bone loss which may require bone grafting.

• A hindfoot alignment view may be helpful.

53.1.3 Nonoperative Options

• Bracing with an over-the-counter lace-up ankle brace, custom ankle-foot orthosis (AFO), or Arizona brace may provide symptomatic pain relief.

53.1.4 Contraindications

• Peripheral vascular disease.

• Active infection, remote osteomyelitis.

• Uncontrolled diabetes.

• Poor soft-tissue envelope.

• Malnutrition.

• Inability to comply with postoperative non-weight-bearing.

• Tobacco use (relative).

53.2 Goals of Surgical Procedure

• Pain relief.

• Solid union of the tibiotalar and subtalar joint arthrodesis.

• Deformity correction with restoration of plantigrade alignment of foot.

• Maximize reconstruction of limb length after bone loss.

• Maximize restoration of activity.

53.3 Advantages of Surgical Procedure

The primary advantages of using an intramedullary nail (IMN) for tibiotalocalcaneal (TTC) fusion are mechanical. The nail is a load-sharing device that demonstrates higher bending stiffness, increased rotational stability, and the capability for dynamic compression in comparison to other forms of internal fixation. It can achieve distal fixation to the calcaneus, better than with plates or screws alone.

The TTC nail is a powerful tool in cases with loss of the talar body, working well with bulk allograft to fill the bony defect; it also extends the indications for tibiocalcaneal arthrodesis because of the strong fixation in the calcaneus.

53.4 Key Principles

• Use of the nail is simply a form of fixation.

• The key to and challenge of the procedure is the surgical skill to do the following, which can be difficult, especially with bone loss and large deformity:

Prepare good bone surfaces with excellent contact and apposition.

Fashion the bony construct in proper alignment in three planes.

• Bone grafting to fill defects and augment healing.

• Satisfactory alignment in hindfoot valgus (coronal plane), ankle dorsiflexion (sagittal plane), external rotation (axial plane), and translation of the foot relative to tibial axis.

• Some degree of medialization of the foot relative to the tibia to aid nail placement.

53.5 Preoperative Preparation and Patient Positioning

53.5.1 Surgical Approach

A variety of surgical approaches are possible, according to surgeon preference, locations and type of deformity, previous incisions and implants, and soft-tissue issues.

• An anterior approach to the ankle with a lateral approach to the subtalar joint is commonly utilized. It provides a familiar view of both joints for most orthopaedic surgeons. It is best used for patients without severe varus/valgus deformity.

• An extensile lateral approach is useful with large deformities, especially in valgus. The fibula may be harvested and used as autograft.

• Combined limited anterior ankle and lateral subtalar incisions can be used when there is minimal deformity.

• A posterior, Achilles-splitting approach with the patient prone is valuable in cases of poor anterior soft-tissue envelope or large talar defect. In the latter situation, grafting from the posterior tibial to the calcaneal tuberosity mechanically augments the salvage. The malleoli can be resected and used as autograft. Intraoperative evaluation of hindfoot alignment is easier with patient prone.

• While uncommon, a medial approach to both the ankle and subtalar joints can be done with careful dissection of the neurovascular structures and a medial malleolar osteotomy.

53.5.2 Patient Positioning

• As above, the patient may be positioned in the supine, lateral, or prone position.

• A thigh tourniquet is utilized.

• The knee should be prepped into the sterile field to assist assessment of alignment.

• The patient should be positioned so that the foot is just at the end of the table to facilitate nail placement and imaging.

53.6 Operative Technique

53.6.1 Joint Preparation

• In a patient with good alignment and adequate bone stock, preparation for arthrodesis saves the shape of the joints, removing only the remaining cartilage and sclerotic bone, with sharp curettes and osteotomes. The subchondral bone can be either carefully removed to expose the cancellous surface, while preserving bone contour, or thoroughly perforated with a drill bit and/or “fish-scaled” with a sharp, narrow osteotome.

• Significant bony defects require more surgical creativity, in order to make a structurally sound construct. It is helpful to expose cancellous bone and create surfaces with wide contact, especially if structural bone graft is required.

• Hindfoot valgus is corrected first and foremost by external rotation of the calcaneus relative to the talus. The talus must be seated beneath the center of the tibial plafond, with simultaneous attention to rotation and coronal plane tilting.

• Shortening of the limb is often necessary, and has been shown to be consistent with good clinical results in patients with bone loss due to avascular necrosis of the talus.

• If the bone loss is very large, bony defects can be filled with use of a femoral head allograft, and augmented with malleable bone preparations that contain stem cell lines for bone growth, which help to fill defects.

53.6.2 Fixation