Comparison of First- and Second-Generation Fixed-Bearing Total Ankle Arthroplasty Using a Modular Intramedullary Tibial Component

Abstract

Background: This series reviews the clinical and radiographic outcomes of patients who underwent total ankle replacement (TAR) using first- and second-generations of a modern fixed-bearing prosthesis utilizing a modular intramedullary stem.

Methods: A consecutive series of first- and second-generation primary TARs with modular intramedullary stems were identified. Clinical outcome data were collected prospectively--including visual analog scale for pain, American Orthopaedic Foot & Ankle Society hindfoot-ankle, Short Musculoskeletal Function Assessment, and Short Form-36 scores. Preoperative coronal plane deformity and correction of deformity after TAR were assessed. Complications, subsequent procedures, and failure rates were compared. A total of 193 first- and 56 second-generation patients were identified with a mean follow-up of 3.7 and 2.1 years, respectively.

Results: Clinical outcome data reflected significant improvements at 1 year postoperatively, and improvements were maintained at 2-year follow-up for each group. Improvement in visual analog scale scores were significantly better in the second-generation group at 1 year postoperatively, but this was not maintained at 2 years. Mean coronal tibiotalar angles for ankles with preoperative varus or valgus deformities were significantly improved. Correction was maintained until final follow-up, with no significant differences in deformity improvement between groups. The rate of reoperation at 2 years postoperatively on the affected foot or ankle subsequent to the index ankle replacement for patients in the first-generation group (18.5%) was higher compared to the second-generation group (15.9%), but the time until reoperation was not statistically significant (P = .376). The implant failure rate was higher in the first-generation group (6.0%) compared to the second-generation group (2.6%) at 2 years postoperatively, but the time until failure was not significantly different (P = .295).

Conclusion: Patients who underwent TAR with a first- or second-generation fixed-bearing prosthesis with an intramedullary tibial component demonstrated significant improvements in all measures of pain and function with sustained improvements in coronal plane alignment. The second-generation prosthesis demonstrated slightly better improvements at 1 year and was associated with lower reoperation and implant failure rates.

Level of evidence: Level II, comparative series.

Keywords: INBONE; ankle arthritis; ankle arthroplasty; total ankle replacement.