Differences in gait analysis and clinical outcome after dynamic fixation or screw fixation in acute syndesmosis tear: a prospective randomized pilot study.

INTRODUCTION

Acute syndesmosis tears can be treated by static screw or dynamic fixation. Various studies have compared these techniques regarding postoperative outcome. However, to our knowledge, no study has used 3D-instrumented gait analysis (IGA). We hypothesized that a dynamic fixation would perform non-inferior to screw fixation in terms of biomechanical and clinical outcomes.

MATERIALS AND METHODS

Patients were prospectively randomized to both groups. All patients received the same follow-up rehabilitation and consultations (6 and 12 weeks; 6 and 12 months) postoperatively. Standardized questionnaires were used to objectify pain and ankle function. At 6 months follow-up, IGA was conducted additionally to objectify the biomechanical outcome.

RESULTS

Twenty-five patients in the dynamic fixation (DF) group using TightRope® and twenty-five in the screw fixation group (SF) completed gait analysis. The DF group showed significantly higher mean values for maximum moment in the affected ankle joint (DF: 1.40 ± 0.21 Nm, SF: 1.23 ± 0.30 Nm; p = 0.023) and the unaffected ankle joint (DF: 1.52 ± 0.20 Nm, SF: 1.37 ± 0.27 Nm; p = 0.035). The difference between the affected and unaffected ankle joint was significantly higher in the SF group for active plantarflexion (DF: 1.52 ± 0.20°, SF: 1.37 ± 0.27°; p = 0.035). Both dynamic and screw fixation groups exhibited significantly reduced plantarflexion during the push-off and early swing phase, with moments and powers in the ankle joint also significantly impaired.

CONCLUSIONS

Our study demonstrated that dynamic fixation has better or similar biomechanical and clinical outcomes compared to screw fixation. Future research should focus on biomechanical differences during gait as well as clinical outcomes in case of earlier weight-bearing after dynamic fixation.

TRIAL REGISTRATION NUMBER (TRN): DRKS00013562 Date of Registration: 07/12/2017.