Abstract
Research Type:
Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies
Introduction/Purpose:
Robust tibial stem fixation was shown to reduce the risk of mechanical failure in total ankle replacement (TAR). However, caution in the use of tibial stems was advised in the past. Authors suggested that drilling across the subtalar joint and through the talus may increase the risk of talus-related complications such as talar osteonecrosis or subtalar arthritis. Nevertheless, the clinical outcomes of the INBONE II® TAR (Stryker, Mahwah, NJ), which utilizes trans-talar drilling, have been very positive, suggesting the concerns with trans-talar drilling may not be warranted. To clarify the potential impact of trans-talar drilling we sought to isolate this variable by comparing the talus-related and subtalar joint-related radiographic and clinical outcomes of INBONE II® TAR talar components placed with or without trans-talar drilling.
Methods:
A retrospective cohort study was conducted on patients who received a primary TAR with an INBONE II® talar component, paired with either a stemmed (INBONE II®,) or non-stemmed (INFINITY®, Stryker, Mahwah, NJ) tibial component. Two cohorts were analyzed. The control cohort (Non-drilled) received an INBONE II® talar component paired with an INFINITY® tibial component which did not require trans-talar drilling. The study cohort (Drilled) received an INBONE II® talar component paired with an INBONE II® tibial component which required trans-talar drilling. The primary outcome parameters were 1) talar component failure requiring revision, and 2) subtalar joint fusion indicated or performed during a 2-year follow-up. Radiographic assessment was performed at 2-year follow-up to identify secondary outcome parameters: Signs of talar osteonecrosis (talar component subsidence, talar cysts, sclerosis, radiolucency, and fractures). Additionally, clinical outcomes were evaluated using the Ankle Osteoarthritis Scale (AOS) at the time of enrollment and at one year postoperatively.
Results:
89 patients with a minimum of 2-year follow-up were included, 25 patients in the control (Non-drilled) cohort and 64 patients in the study (Drilled) cohort. No revision due to failure of the talar component and no subtalar fusion were performed in either of the two cohorts during follow-up . There were no significant differences in talar subsidence (p = 0.98), cysts (p = 0.09), sclerosis (p = 0.4), or radiolucency (p = 0.8). AOS scores were similar between cohorts at enrollment (p = 0.08) and at the one year (p = 0.96) and improved significantly at one year (Drilled cohort from 58.89 ± 17.64 to 10.28 ± 23.37 (p < 0.01), Non-drilled cohort from 52.33 ± 16.54 to 11.44 ± 22.59 (p < 0.01).
Conclusion:
At 2 years follow-up, 2 cohorts of primary TARs utilizing a standard talar component (INBONE II®) performed with or without trans-talar drilling experienced no talar component failures or subtalar degeneration requiring revision. Both cohorts had significant improvements in AOS scores with no differences in any radiographic measures of talar or subtalar joint complications. These findings suggest that use of trans-talar drilling to insert stemmed tibial TAR components does not increase the risk of talar component failure, talar osteonecrosis or subtalar joint degeneration.