Outcomes of Tibiotalocalcaneal Arthrodesis using a Custom Three-Dimensional Printed Titanium Truss Implant

Abstract

Category:Ankle; HindfootIntroduction/Purpose:Tibiotalocalcaneal (TTC) arthrodesis (fusion) is considered a salvage procedure for patients with severe hindfoot and ankle pathology. Several techniques have been described for TTC fusion, including the use of an intramedullary rod, plate and screw constructs, screws only, and external fixation/frames. Recently, 3D printing technology has allowed for a new technique to treat large hindfoot and ankle osseous defects with a custom three-dimensional (3D) titanium truss implant. These implants are specifically designed based on preoperative patient computed tomography (CT) scans. Early studies have shown promising radiographic and functional results, though these have been limited largely to expert opinions and case reports. The purpose of this study is to evaluate the clinical, radiographic, and functional outcomes of TTC arthrodesis using a custom 3D titanium truss implant.Methods:A retrospective review of patients who have undergone TTC arthrodesis utilizing a custom 3D-printed titanium truss implant (4WEB Medical, Inc., Frisco, TX) with a fellowship-trained orthopaedic foot and ankle surgeon at a single institution was performed. Patients <18 years old, and those undergoing TTC arthrodesis using any other primary method of filling osseous defects (i.e. femoral head allografts, autografts) were excluded. Patient demographics including age, sex, body mass index (BMI), smoking status, laterality of surgery, co-morbidities (diabetes mellitus, rheumatoid arthritis), preoperative diagnosis, previous hindfoot or ankle surgeries, and any postoperative complications were collected. Patients at least one year removed from the procedure were contacted to complete the Foot and Ankle Ability Measure (FAAM) Activities of Daily Living (ADL) subscale, along with the Visual Analog Scale for pain (VAS) and the Short Form-12 questionnaire (SF-12). Postoperative radiographs were reviewed to assess ankle and hindfoot alignment, implant integrity and any osseous abnormalities.Results:Eighteen patients underwent TTC fusion using custom titanium truss implants and were eligible for follow-up and analysis. Average patient age at the time of surgery was 58.7 years, and average BMI was 30.25 kg/m2. Seven patients (38.9%) were either current or former smokers, and 3 patients (16.7%) were diabetic. On average, patient FAAM ADL scores improved from 33.23 preoperatively to 59.56 (p=0.023), while VAS pain scores decreased from 59.07 to 34.22 (p<0.001). SF-12 Mental Health scores increased from 45.45 to 56.42 (p=0.031), while Physical Health scores improved mildly from 28.78 to 31.75 (p=0.110). Two patients (11.1%) had significant postoperative complications; one patient went on to require below knee amputation, and one patient demonstrated incomplete healing with implant loosening at their most recent follow-up.Conclusion:We have shown that custom titanium truss implants are viable and effective for use in TTC fusion. Use of such implants resulted in significant functional improvement among the cohort with low rates of complications and subsequent surgical interventions.