Early Radiographic and Clinical Outcomes of the Cadence Total Ankle Replacement System

Abstract

Category: Ankle Arthritis; Ankle; Other Introduction/Purpose: The Cadence Total Ankle System (Smith and Nephew, Memphis, TN) is a two-component, fixed-bearing fourth generation total ankle arthroplasty (TAA) system that was introduced for clinical use in 2016. Few studies have investigated short-term outcomes of this new TAA system, and no outcomes have yet been reported by independent authors. The purpose of this study was to report non-inventor, non-industry funded survivorship, radiographic and clinical outcomes, and early complications following use of the new fourth generation TAA system at a minimum of 2 years. Methods: This is a single-center retrospective study of patients who underwent TAA by two surgeons with the Cadence between January 2017 and September 2018. There were 50 ankles in 50 patients, and 48 (96%; mean age of 66.1 years) patients were evaluated at a minimum 2-year follow-up. Two patients were lost due to death and refusal to participate in the study. Patients had an average follow-up of 33.6 (range, 24-50) months. Radiographic outcomes included preoperative and postoperative tibiotalar alignment (TTA) on anteroposterior radiographs of the ankle, sagittal tibial alignment (STA) on lateral radiographs of the ankle, and periprosthetic cyst formation (greater than 5mm in size) and cyst location. Data regarding reoperations and revisions were also collected. Patient-reported outcomes were assessed using Patient Reported Outcomes Measurement Information System (PROMIS). Subgroup analysis was performed to assess for associations between preoperative deformity, postoperative implant alignment, PROMIS scores, and periprosthetic cyst formation. Results: Survivorship of implant was 93.7%, with 3 revisions, 1 due to infection and 2 due to loosening of the implant (one tibial and one talar component). Three patients had reoperations (6.3%): 2 for irrigation and debridement for cellulitis, and 1 for gutter debridement due to medial gutter impingement. Preoperatively, 9 ankles had varus alignment (mean TTA 77.9 degrees), 20 had neutral alignment (mean TTA 90.2 degrees), and 13 had valgus alignment (mean TTA 102.9 degrees). Postoperatively, TTA and STA significantly improved, and all patients demonstrated neutral coronal alignment (TTA between 85 and 95 degrees). Fifteen patients (35.8%) developed periprosthetic cysts, all on the tibial side. PROMIS scores improved after surgery in all domains except Depression (Table 1). Patients with postoperative periprosthetic cysts had a smaller preoperative STA and a worse postoperative PROMIS Physical function and Pain interference domain than patients without periprosthetic cysts (p<0.05). Conclusion: This study demonstrated excellent minimum 2-year clinical and radiographic outcomes, along with low revision and reoperation rates, of this new fourth generation TAA system. Future studies with longer follow-up, especially on patients with periprosthetic cysts, are necessary to investigate the long-term complications and understand the long-term functional and radiographic outcomes of this implant.