Tibiotalar Fusion: Open

Meshal Alhadhoud and Mark Glazebrook

Abstract

The open tibiotalar fusion with fibular sparing Z-osteotomy (FSZO) technique increases stability of the ankle fusion to maintain alignment when compared with fibular-sacrificing ankle arthrodesis due to preservation of the fibula acting as lateral strut. Excellent surgical exposure of the weight-bearing surfaces of ankle joint may help the surgeon to perform a more thorough joint debridement and allow for better correction of any preexisting deformities, potentially decreasing malunion and nonunion rates. Preservation of the anatomy of the fibula allows for the option of future revision to a total ankle arthroplasty, which is a familiar lateral approach to an orthopaedic surgeon that is easy and safe. These potential benefits suggest that FSZO ankle arthrodesis may prove to be a superior or at least an equally effective technique for ankle arthrodesis in treatment of end-stage ankle arthritis.

Keywords: fibular sparing, Z-osteotomy, ankle arthrodesis

46.1 Indications

• Ankle arthritis:

Most commonly posttraumatic.

46.1.1 Clinical Evaluation

• In order to formulate an appropriate differential diagnosis and successful treatment, a careful initial history must be obtained, then a systematic physical examination in order to identify the major joint dysfunction. Typically, patients complain of anterior ankle joint pain that increases with walking for short period or prolonged standing, and decreases with rest. A careful history taking should include review of ankle fracture, tibia plafond fracture, ankle dislocation, ankle sprain, and osteochondral lesion of the talus.¹ Systemic diseases include rheumatoid arthritis; systemic lupus can cause ankle arthritis, but it is not common as posttraumatic arthritis.²

• Inspect the ankle joint for any previous surgical scars, swelling, and deformities.

• Palpation at the medial and lateral joint space induces pain; periarticular osteophytes can be palpated.

• There is decrease of range of motion in a sagittal plane, usually forced motion associated with a pain.

• In long-standing arthritis, varus or valgus deformity forms and gait abnormality will occur.

• Neurovascular examination is required.

46.1.2 Radiographic Evaluation

• Weight-bearing radiographs include a true anteroposterior, lateral, and mortise views of the ankle. Hindfoot alignment view can be helpful to measure the severity of the deformity.³ Decrease of joint space, periarticular osteophytes, subchondral sclerosis, cyst formation, and ankle malalignment can be seen in the anteroposterior view, and anterior and posterior impingement seen in the lateral view. Always obtain a long film to evaluate the lower limb for any deformity.

• There is no role of MRI (magnetic resonance imaging) and CT (computed tomography) scan in ankle arthritis diagnosis. SPECT-CT (single-photon emission computed tomography and CT) scan has 94% sensitivity and 95.45% specificity in detecting joint arthritis, around the foot and ankle.⁴

46.1.3 Nonoperative Options

• Activity modification.

• Bracing.

• Injections (corticosteroids and viscosupplementation).

• Medications (analgesia and anti-inflammatory) and nutritional supplements (chondroitin and glucosamine).

• Patient education.

• Physical therapy.

• Shoe wear modification (rocker-bottom shoe wear) and shoe orthotics.

• Weight reduction.⁵

46.1.4 Contraindications

• Active infection.

• Charcot neuropathic process.

• Generally sick patient or those with poor circulation.

46.2 Goals of Surgical Procedure

Recently, there has been increase of periarticular arthritis in the midfoot and hindfoot joints in the long-term follow-up of patients with prior ankle arthrodesis. This has led some surgeons to convert ankle arthrodesis to total ankle arthroplasty, which is contraindicated if the lateral malleoli are scarified. This chapter describes a fibular sparing Z-osteotomy (FSZO) surgical technique that is designed to preserve the anatomy of the ankle joint while providing excellent exposure to correct preexisting deformity and allowing rigid stable fixation.

46.3 Advantages of Surgical Procedure

The lateral approach is familiar to all surgeons who fix ankle fractures. It provides excellent exposure for correction of deformity and stable fixation while avoiding neurovascular structures located anteriorly and medially. The lateral approach spares the anterior soft tissue that will need to be used if conversion to a total ankle arthroplasty is necessary.

46.4 Key Principles

• Extensile lateral approach of the ankle.

• Z-osteotomy of the fibula.

• Taking medial third of the fibula to use as bone graft.

• Clear visualization of all articular surfaces.

• Using osteotome in joint preparation.

• Insert the talus screw first to achieve good compression at the fusion site.

46.5 Preoperative Preparation and Patient Positioning

• Open discussion with the patient on the risks, benefits, and limitations of ankle arthrodesis.

• Patient history and physical examination should be taken to determine medical fitness for surgery.

• Patient should also be examined for ipsilateral lower extremity deformities above the ankle that may need to be corrected first.

• Patient should have standing lateral and anteroposterior radiographs of the foot and ankle to determine if there is preexisting deformity or fracture that may need concurrent treatment.

46.6 Operative Technique

• The patient is positioned on the operating table in the lateral decubitus position with the operative limb up. This facilitates easy approach to the ankle joint and avoids interference from the operating table that the surgeon may experience in the supine position.

• Further, the lateral position also provides an excellent view of the coronal and sagittal hindfoot alignment, which is essential for successful positioning of ankle arthrodesis.

• A tourniquet is applied to the thigh and inflated to 350 mm Hg. The leg is prepared, draped, and then sterilized using a soap scrub before betadine painting.

• The incision is made on the lateral aspect of the ankle directly over the fibula starting distal in the sinus tarsi region, then carried in a curved fashion proximally to a point approximately 10 cm from the initiation of the incision (Fig. 46.1).

• The skin and subcutaneous soft tissue are then incised down to the fibula with care taken not to cut neural vascular structures.

• Soft tissue is then gently dissected off the anterior and posterior border of the fibula to allow placement of retractors to visualize the site of the FSZO (Fig. 46.2).

• A mini-sagittal saw with a long thin blade is used to make the initial 2-cm cut (Fig. 46.3) along the longitudinal axis of the fibula in the sagittal plane, beginning approximately 2 to 3 cm proximal to the ankle joint. The second cut is made in the axial plane beginning at the fibula (Fig. 46.4), thus separating the fibula into distal and proximal portions.

• The distal portion of the fibula may then be rotated externally, using a posterior soft-tissue hinge, thus providing excellent exposure (Fig. 46.5) to the weight-bearing surface of the ankle joint, allowing distraction of the joint using a laminar spreader (Fig. 46.6).