Fixation of ankle syndesmotic injuries: comparison of tightrope fixation and syndesmotic screw fixation for accuracy of syndesmotic reduction.

BACKGROUND

Ankle syndesmotic injuries are complex and require anatomic reduction and fixation to restore the normal biomechanics of the ankle joint and prevent long-term complications.

PURPOSE: The aim of this study is to compare the accuracy and maintenance of syndesmotic reduction using TightRope versus syndesmotic screw fixation.

STUDY

DESIGN

Cohort study; Level of evidence, 2.

METHODS

This cohort study included consecutive patients treated for ankle syndesmotic diastases between July 2007 and June 2009. Single slice axial computed tomography (CT) scans of both the ankles together were performed at the level of syndesmosis, 1 cm above the tibial plafond. A greater than 2-mm widening of syndesmosis compared with the untreated contralateral ankle was considered significant malreduction. Clinical outcomes were measured using the American Orthopaedics Foot and Ankle Society (AOFAS) and Foot and Ankle Disability Index (FADI) scores.

RESULTS

Forty-six of 55 eligible patients participated in the study; 23 patients were in the TightRope group and 23 in the syndesmotic screw group. The average age was 42 years in the TightRope and 40 years in the syndesmotic screw group, and the mean follow-up time was 2.5 years (range, 1.5-3.5 years). The average width of normal syndesmosis was 4.03 ± 0.89 mm. In the TightRope group, the mean width of syndesmosis was 4.37 mm (SD, ±1.12 mm) (P = .30, t test) compared with 5.16 mm (SD, ±1.92 mm) in the syndesmotic screw group (P = .01, t test). Five of 23 ankles (21.7%) in the syndesmotic screw group had syndesmotic malreduction, whereas none of the TightRope group showed malreduction on CT scans (P = .04, Fisher exact test). Average time to full weightbearing was 8 weeks in the TightRope group and 9.1 weeks in the syndesmotic screw group. There was no significant difference between the TightRope and syndesmotic screw groups in mean postoperative AOFAS score (89.56 and 86.52, respectively) or FADI score (82.42 and 81.22, respectively). Regression analysis confirmed malreduction of syndesmosis as the only independent variable that affected the clinical outcome (regression coefficient, -12.39; t = -2.43; P = .02).

CONCLUSION

The results of this study indicate that fixation with TightRope provides a more accurate method of syndesmotic stabilization compared with screw fixation. Syndesmotic malreduction is the most important independent predictor of clinical outcomes; therefore, care should be taken to reduce the syndesmosis accurately.