Abstract
There are limited options for failed total ankle arthroplasty (TAA) with major talar bone loss and component subsidence. Surgical options for this condition include revision arthroplasty, salvage arthrodesis, or amputation. Revision arthroplasty generally has been considered in situations of loose components with minimal bone loss or use of expensive custom-fabricated prosthetic components with elongated stems. Historically, failure that involves major talar bone loss has been considered resistant to reconstruction, and responsive only to complex arthrodesis or amputation. In this report, we describe a unique method of restoring talar support and preserving ankle function after failed TAA with major talar bone loss and component subsidence. Talar reconstruction using metal-reinforced bone cement augmentation is combined with the Inbone (Wright Medical Technology, Inc., Arlington, TN) total ankle system to restore talar height and ligamentous support. This technique has been used successfully in the last 4 years for various patterns of talar bone loss and obviates the need for custom components. When successfully performed, the revision technique results in restoration of mechanical alignment, anatomic height, and component support, in addition to providing substantial symptomatic relief.
Keywords: bone, cement augmentation, complication, revision surgery, talus, tibia
Despite the continued success in total ankle replacement in recent years, in the event of prosthesis failure, the surgeon is often faced with critical loss of bone mass and deformity. In a review of 20 clinical series on total ankle arthroplasty (TAA), there is a need for revision surgery in 12.4% of cases after 5.3 years (1). The various failure patterns include: deep infection, aseptic loosening, periprosthetic osteolysis, and component subsidence. One of the greatest challenges in TAR revision surgery is the management of aseptic loosening of the talar component with talar subsidence. This bone loss can occur through direct mechanical fatigue of the underlying trabecular bone or through periprosthetic osteolysis from premature or accelerated polyethylene wear. Talar component subsidence results in a shift of the ankle joint axis as well as loss of talar height and impingement of the talomalleolar facets (2). The bone loss and subsidence can be severe enough to erode completely through the talar body and encroach upon or even invade the subtalar joint (2).
There are many authors who have suggested that salvage is the only option available in failed TAR that involves major subsidence of the talus. These salvage options have included ankle arthrodesis (3–15) as well as amputation (16–20). In the setting of major bone loss, conversion to arthrodesis is complicated and associated with increased hindfoot stiffness and non-union rate (21). Custom prosthetic devices have also been suggested for revision (2,21,22). However, custom devices are difficult to insert and do not provide for versatile positioning of the talar component. Furthermore, the interface between the underside of the revision talar component and the native bone is irregular and inconsistent from patient to patient. As such, during insertion, additional bone needs to be removed to provide a stable, flat configuration for the placement of the talar component.
The use of metal-reinforced cement augmentation has been used successfully in hip and knee revisions (23,24). The primary advantages are the ability to substitute for vacant bone and to provide a stable interface between the ultimate components and the native bone mass. This technique can be performed with readily available materials and avoids the need for a custom prosthesis. To date, this concept has not been adapted to the ankle when there is failure of a joint replacement. The purpose of this article is to provide a versatile technique for the management of failed TAR with substantial talar bone loss based on the early success of this procedure and lack of other suitable options for preservation of function.
Indications and Contraindications
Candidates for use of metal-reinforced cement augmentation revision of failed TAR are patients with aseptic component loosening with minor or major talar bone loss (Fig. 1). These patients would also be considered for tibial-talar-calcaneal fusion, ankle fusion, or custom prosthetic reconstruction. The technique relies on existing bone stock of the calcaneus in combination with intact bimalleolar ligamentous support. The goal of this reconstruction is to restore talar height and prosthetic component alignment with a durable mechanical support. Any significant loss of malleolar or medial ligamentous support, poor soft tissue coverage quality, and failure of custom metal-augmented prostheses are relative contraindications to performing this procedure. Active infection is an absolute contraindication for this technique.
Preoperative Planning
Patient Evaluation
The evaluation consists of a comprehensive lower extremity examination and workup with diagnostic imaging/laboratory testing. The patients undergo a methodical lower extremity examination in both a non-weight-bearing and weight-bearing attitude. The overall quality of soft tissues, leg and foot alignments, and functional gait status is assessed. Any previous insults to the cutaneous envelope or soft tissue compartments are analyzed with careful assessment of the neurovascular status. Evaluation for equinus contracture or other tendon disorders are also ruled out. Structural analysis takes into account any hindfoot or supramalleolar misalignments, relative malleolar position shifts, and residual joint excursion and flexibility of the hindfoot.
Diagnostic Imaging and Testing
Preoperative preparation also entails baseline weight-bearing radiographs of the foot and ankle to determine basic segmental alignment and delineate the extent of bone loss. If there is concern about a complicating limb malalignment, standing long-leg films are obtained. To better comprehend the morphology of the talar subsidence and quality of periprosthetic bone, computerized tomography is helpful to fine tune the surgical plan. If deep infection is suspected, routine screening is performed with complete blood count, sedimentation rate, and C-reactive protein. Clinical impressions are correlated with radiographic findings to determine if ancillary procedures need to be included in the surgical plan.
Surgical Technique
The patient is placed supine on a radiolucent operating table and typically placed under general anesthesia. The patient is positioned with sand bag under the ipsilateral hip and the contralateral leg suspended in a lithotomy position with a leg holder or stirrup. A thigh tourniquet is positioned and placed on standby to use as needed during the procedure. After standard skin preparation and draping, the lower leg is fully exposed to include the patella. An antimicrobial incise barrier drape (Ioban; 3M, St. Paul, MN) is then circumferentially adhered to the exposed extremity in preparation for the incision.
Surgical access to the ankle joint is generally through the previous longitudinal anterior incision. If ancillary procedures are necessary, careful incisional planning is needed to ensure an adequate skin bridge between exposures. The incisions are deepened in a full thickness fashion with careful dissection adjacent to the dorsalis pedis neurovascular bundle, which can be difficult to identify because of extensive scarring. Dual sets of aerobic and anaerobic cultures are obtained from the bony cavities followed by initiation of the appropriate antibiotic prophylaxis. Once the ankle joint is fully exposed, the components are assessed. Components that are well fixated should be removed last after additional working space has been established. Removal must be done in a meticulous manner and is facilitated with the use of thin or flexible osteotomes to preserve bone mass...
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