Outcomes and Complications of the INFINITY Total Ankle: A Systematic Review

Revision Total Ankle Arthroplasty Using the INBONE II System

BACKGROUND

The utilization of total ankle arthroplasty (TAA) for managing severe ankle osteoarthritis has become increasingly common, leading to a higher occurrence of revision TAA procedures because of failure of primary TAA. This study aims to examine the clinical results associated with revision TAA using the INBONE II system. Given the growing number of TAA revision procedures and a focus on motion-preserving salvage options, we evaluated our early experience with revision TAA.

METHODS

A retrospective analysis was conducted on a group of 60 presumed noninfected patients who underwent revision TAA with the INBONE II system. Detailed information was collected on patient demographics, implant characteristics, concurrent procedures, and complications. The implant survival was estimated using Kaplan-Meier analysis.

RESULTS

The study revealed high complication rates but generally fair clinical outcomes for revision TAA using the INBONE II system. Complications were observed in 22 patients (36.7%), including persistent pain (n = 6), nerve injury/impingement (n = 5), infection (n = 3), fracture (n = 3), implant failure (n = 3), impaired wound healing (n = 2), and osteolysis (n = 3). The 3-year survivorship rate from reoperation was 92.0% (82.7%-100.0%) whereas the 3-year survivorship rate from major complications was 90.4% (80.8%-100.0%).

CONCLUSION

We report high complication rates but generally fair clinical results for revision TAA utilizing the INBONE II system.

Ankle Osteoarthritis

Ankle osteoarthritis (OA) is less common than knee and hip OA, and 75% to 80% of all presentations are posttraumatic in nature, resulting from either ligamentous or bony injury to the ankle. While the ankle joint cartilage demonstrates capacity for self-restoration, the ankle joint is sensitive to aberrancies in biomechanics and the inflammatory milieu after an injury is thought to contribute to the onset of posttraumatic ankle OA. Conservative care for ankle OA is currently centered on pain reduction, and derivatives that may delay the progression of ankle OA are the subject of ongoing investigation. Surgical management for end-stage ankle OA currently focuses on ankle arthrodesis and total ankle arthroplasty. Specific indication for one procedure over the other is the topic of much debate. While total ankle arthroplasty has become more frequently used with the advent of newer generation systems, ankle arthrodesis may still be favored in younger patients with high-demand occupations.

Two-Year Survivorship and Patient-Reported Outcomes of a Prospectively Enrolled Cohort of INFINITY Total Ankle Arthroplasties

BACKGROUND

The INFINITY total ankle implant is a widely and successfully used option for total ankle arthroplasty. The purpose of this study is to assess the 2-year survivorship, complication rates, patient-reported outcomes, and radiologic findings of prospectively enrolled patients undergoing a fixed-bearing total ankle arthroplasty (TAA). This study sought to determine if factors such as traditional vs patient-specific instrumentation, preoperative degree of arthritis, deformity, or etiology of arthritis impact surgical or clinical outcomes.

METHODS

A total of 143 prospectively enrolled patients (148 ankles) underwent TAA with a fixed-bearing total ankle implant between 2017 and 2019 at 9 different institutions by 9 different surgeons. A total of 116 completed 2-year follow-up. Patients were stratified by instrumentation used, degree of preoperative deformity, the Canadian Orthopaedic Foot and Ankle Society (COFAS) grading system, and etiology of arthritis. Outcomes used included implant survivorship and adverse events within 2 years of surgery. Additionally, patient-reported outcomes and radiographs were collected at 6-month, 1-year, and 2-year postoperatively. PROMs used included Ankle Osteoarthritis Score (AOS), Patient-Reported Outcomes Measurement Information System (PROMIS) global health score, the Foot and Ankle Outcome Score (FAOS), and patient satisfaction (rated from excellent to poor).

RESULTS

Implant survivorship at 2 years was 97.79%. There were 17 reoperations (11.5%), with 4 of the implants requiring revision (2.7%). Significant improvements in all PROMs were observed among all subgroups at all postoperative time points without significant variation between subgroups. Patients classified as COFAS type 2 arthritis preoperatively demonstrated significantly more improvement in FAOS Total Symptom Score at the 1- and 2-year measurements than COFAS type 3 patients at both time points.

CONCLUSION

Total ankle arthroplasty with a fixed-bearing implant system is a safe and reliable treatment option for patients with end-stage arthritis regardless of degree of deformity or COFAS grading.

LEVEL OF EVIDENCE

Level II, prospective cohort study.

Current Trends in Total Ankle Replacement

Ankle arthritis can result in significant pain and restriction in range of motion. Total ankle replacement (TAR) is a motion-preserving surgical option used as an alternative to total ankle arthrodesis to treat end-stage ankle arthritis. There are several generations of TAR techniques based on component design, implant material, and surgical technique. With more recent TAR implants, an attempt is made to minimize bone resection and mirror the native anatomy. There are more than 20 implant devices currently available. Implant survivorship varies among prosthesis types and generations, with improved outcomes reported with use of the more recent third- and fourth-generation ankle implants. Pre- and postoperative assessments of TAR are primarily performed by using weight-bearing radiography, with weight-bearing CT emerging as an additional imaging tool. Preoperative assessments include those of the tibiotalar angle, offset, and adjacent areas of arthritis requiring additional surgical procedures. US, nuclear medicine studies, and MRI can be used to troubleshoot complications. Effective radiologic assessment requires an understanding of the component design and corresponding normal perioperative imaging features of ankle implants, as well as recognition of common and device-specific complications. General complications seen at radiography include aseptic loosening, osteolysis, hardware subsidence, periprosthetic fracture, infection, gutter impingement, heterotopic ossification, and syndesmotic nonunion. The authors review several recent generations of TAR implants commonly used in the United States, normal pre- and postoperative imaging assessment, and imaging complications of TAR. Indications for advanced imaging of TAR are also reviewed. ©RSNA, 2023 Supplemental material is available for this article. Test Your Knowledge questions for this article are available through the Online Learning Center.