Improved Reduction of the Tibiofibular Syndesmosis With TightRope Compared With Screw Fixation: Results of a Randomized Controlled Study.

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, χ). 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.