Improved Reduction of the Tibiofibular Syndesmosis With TightRope Compared With Screw Fixation: Results of a Randomized Controlled Study
Authors:   Canadian Orthopaedic Trauma Society;, Sanders David , Schneider Prism , Taylor Michel , Tieszer Christina , Lawendy Abdel-Rahman 
Published: June 2019

Objective:
To compare the rate of malreduction after high fibular fractures associated with syndesmosis injury treated with open reduction and internal fixation, with either 2 screws or 1 knotless TightRope device.

Design:
Prospective randomized controlled multicenter trial.

Setting:
Eleven academic and community hospitals including Level 1 and Level 2 trauma centers across Canada.

Patients/Participants:
One hundred three patients with OTA/AO 44-C injuries with demonstrated radiographic syndesmosis diastasis or instability after malleolar bony fixation were followed for 12 months after treatment.

Methods:
Open reduction of the syndesmosis was performed in all cases. Fixation was randomized to either TightRope (1 knotless TightRope, group T) or screw fixation (two 3.5-mm cortical positional screws placed across 3 cortices, group S). Surgical techniques and rehabilitation were standardized. All surgeons were trained or experienced in the use of the TightRope device. Follow-up was performed at 2 and 6 weeks, 3, 6, and 12 months.

Main Outcome Measure:
Rate of malreduction based on bilateral ankle computed tomography scan results at 3 months after fixation. Secondary outcome measures included adverse events, reoperation, and validated functional outcomes including the EQ-5D, the Olerud–Molander Ankle Score, the Foot and Ankle Disability Index, and the Work Productivity Activity Impairment Questionnaire. The estimated sample size required to detect a difference in reduction rate was 72 patients, but the estimated sample size required to detect a difference in functional outcome scores was 240 patients, suggesting the study was adequately powered for radiographic results only.

Results:
Overall, the rate of malreduction using screw fixation was 39% compared with 15% using TightRope fixation (P = 0.028, χ2). Analysis of computed tomography results was performed using a 2-mm translation or 10-degree rotation threshold for malreduction and included fibular translation (anterior, posterior); syndesmosis distance (anterior, posterior, and mid); medial compression; and rotation (fibular and articular). Patients in group T had greater anterior translation (5.4 ± 1.8 mm) compared with the contralateral limb (4.3 ± 1.3 mm, P < 0.01) or group S (4.6 ± 1.5 mm, P = 0.05). Group T syndesmoses also had greater diastasis compared with control limb (4.1 ± 1.3 vs. 3.3 ± 1.4 mm, P < 0.01) and less fibular medialization compared with group S (1.04 ± 1.8 vs. 0.3 ± 1.8 mm, P = 0.05). Functional outcome measures demonstrated significant improvements over time, but no differences between fixation groups. Foot and Ankle Disability Index scores at each time interval were 44 ± 22 (T) versus 45 ± 24 (S) (6 weeks), 76 ± 14 versus 73 ± 17 (3 months), 89 ± 10 versus 86 ± 13 (6 months), and 93 ± 9 versus 90 ± 14 (12 months) (all P > 0.2). The reoperation rate was higher in the screw group compared with TightRope (30% vs. 4%, P = 0.02) with the difference driven by the rate of implant removal.

Conclusions:
Based on our results, the TightRope device seems to compare favorably with two, 3.5-mm, 3-cortex screw fixation for syndesmosis injuries.

Level of Evidence:
Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.