SLR - August 2022 - John Constantino, DPM
Reference: Wong MT, Wiens C, LaMothe J, Edwards WB, Schneider PS. In Vivo Syndesmotic Motion After Rigid and Flexible Fixation Using 4-Dimensional Computerized Tomography. Journal of Orthopaedic Trauma. 2022 May. 36:257-264.Level of Evidence: Level IV (Comparative Case Series)
Scientific Literature Review
Reviewed By: John Constantino, DPM
Residency Program: Mount Auburn Hospital - Cambridge, MA
Podiatric Relevance: Syndesmotic injuries are present in 25 percent of ankle fractures. Maintaining reduction of the syndesmotic complex is crucial for optimal long-term function. Historically, syndesmotic injuries have been treated with rigid screw fixation. Increasing evidence demonstrate improve function and reduction with suture bridge or flexible fixation devices. Despite these recent advances, malreduction of the syndesmosis remain a common complication after syndesmotic repair. Understanding the effect on syndesmotic motion and reduction after various fixation methods utilizing 4DCT can aid in maintenance of reduction throughout ankle range of motion.
Methods: Thirteen (13) patients satisfied the inclusion criteria for 4DCT analysis. Seven patients had rigid fixation and six had flexible fixation. Surgery was performed within 14 days of injury. Rigid fixation involved 3.5 mm cortical screws either tricortical or quadricortical. Flexible fixation involved a single knotless TightRope Suture. At 12 months postoperatively 4DCT of bilateral ankles were performed. Patients moved their ankle continuously between dorsiflexion and plantarflexion to their comfortable limits of motion. Ten 4DCT time points were imaged over a 9 second span. Initial static CT scans of bilateral tibias, fibulas, and tali were then utilized to create 3D models at each time point to calculate multiple syndesmotic measurements. The anterior, middle and posterior syndesmotic distance (ASD, MSD, PSD), tibiofibular clear space (TFCS), tibiofibular overlap (TFO), sagittal translation, fibular rotation and syndesmotic area were measured. Dependent sample t tests were used to compare ROM of ankles between subjects. Syndesmotic measurements were analyzed using linear mixed-effect models.
Results: There was no difference in ankle ROM between dorsiflexion and plantar flexion, sagittal translation or fibular rotation between ankles fixed with rigid or flexible fixation. Both fixation types had reduced ROM compared with contralateral ankles. There were no differences in syndesmotic position for contralateral uninjured ankles between the rigid and flexible fixation groups. In all measures of medial-lateral translation, rigid fixation led to a wider syndesmosis in neutral dorsiflexion. Only differences in MSD and syndesmotic area were significant compared with patient’s contralateral uninjured ankles. Syndesmotic area was significantly greater after rigid fixation. There was significantly less motion in the rigid fixation group compared with motion in the flexible fixation group for MSD, TFCS and TFO.
Conclusions: This is the first study to evaluate in vivo motion after treatment of syndesmotic injuries. The study demonstrated greater MSD, TFCS and syndesmotic area in rigid fixation compared with uninjured ankles when measured n dorsiflexion and plantarflexion. There were no significant differences in syndesmotic position between flexible fixation and uninjured ankles supporting previous work which showed that overcompression can be minimized with appropriate suture button tensioning and that flexible fixation provides better maintenance of reduction in medium and long term. Rigid fixation led to significantly subphysiologic motion in MSD, PSD, TFCS, TFO and syndesmotic area despite screw breakage or removal. Flexible fixation adequately stabilized the distal tibiofibular joint and provided more physiologic motion. This motion may contribute to superior reduction and function reported with flexible fixation which could dictate surgical decision making of podiatric surgeons.