Radiographic evaluation of INBONE total ankle arthroplasty: a retrospective analysis of 30 cases.

Objectives: The objectives of this work were to retrospectively describe the radiographic assessment of INBONE total ankle arthroplasty in 30 patients using validated linear and angular measurements and to correlate these findings with the final surgical outcome over a 2-year follow-up period.

Materials And Methods: Thirty consecutive patients (21 females, nine males; mean age, 64.8 years) underwent INBONE total ankle arthroplasty during 2007-2011. After IRB approval, a retrospective pre- and post-operative radiographic analysis was performed using validated linear and angular measurements. The pre- and post-operative assessment included the tibial angle, talar angle, tibial slope, and coronal deformity. Post-operative measurements also included the talocalcaneal angle, joint space height, talar height, lateral tibial component angle, lateral talar component angle, and anteroposterior tibial component angle. The post-operative bone loss, subluxation, positioning, and subsidence were also assessed. Statistical analysis was performed using two-sample t test and Fisher's exact test.

Results: Out of 30 patients, 23 had a successful clinical outcome with intact prosthesis at a 2-year follow-up. The only variables with significant correlation (p < 0.05) to the post-surgical outcome were the lateral talar component angle (p = 0.002) and the mean difference between pre- and post-operative tibial slope (p = 0.001). The coronal deformity had significant mean difference between pre- and post-operative values (p < 0.001); however, it lacked a significant correlation to the final surgical outcome. None of the categorical variables had a significant correlation with post-surgical outcome.

Conclusions: In our retrospective study, only the lateral talar component angle and the mean difference between the pre- and post-operative tibial slope had significant correlation with post-surgical outcome in INBONE ankle arthroplasty. These measurements may be helpful in radiographic assessment of the INBONE ankle arthroplasty.