Surgical treatment of syndesmotic diastasis: emphasis on effect of syndesmotic screw on ankle function.

Fifty-two consecutive adult patients with syndesmotic diastasis (SD) were treated with closed anatomical reduction and stable fixation by a trans-syndesmotic cancellous screw. A short leg splint was prescribed for a six week postoperative period. Treatment outcomes of syndesmotic screw removal at various time points were studied and compared (group 1 at six weeks, group 2 at three months and group 3 at an average of nine months). Recurrence of SD, incidence of syndesmotic screw breakage and ankle function were compared among the three groups. Recurrence of SD occurred in 15.8% (3/19) of patients in group 1, 15.0% (3/20) in group 2 and 0% (0/13) in group 3 (p = 0.054). Breakage of the syndesmotic screw occurred in three patients within three months (group 2, 15.0%) and in two patients beyond three months (group 3, each at six and 12 months, 15.4%). None of the group 1 patients experienced screw breakage (p = 0.034). Forty-three patients (82.7%) were classified as having satisfactory outcomes. Ankle function did not significantly differ among the three groups (p = 0.191), with or without syndesmotic screw breakage (p = 0.343) and with or without SD recurrence (p = 0.218). In conclusion, restriction of daily activity for at least three months is required to prevent recurrence. Removal of the syndesmotic screw at six weeks may prevent its breakage but increases the risk of recurrence. Over an average follow-up of 19 months, SD recurrence does not lead to deterioration in ankle function.