SLR - April 2015 - N. Jake Summers

A Prospective Randomised Study Comparing TightRope and Syndesmotic Screw Fixation for Accuracy and Maintenance of Syndesmotic Reduction Assessed with Bilateral Computed Tomography

Reference: Kortekangas T, Savola O, Flinkkila T, Lepojarvi S, Nortunen S, Ohtonen P, Katisko J, Pakarinen H.  A Prospective Randomised Study Comparing TightRope and Syndesmotic Screw Fixation for Accuracy and Maintenance of Syndesmotic Reduction Assessed with Bilateral Computed Tomography.  Injury. 2015 Feb 21.

Scientific Literature Review

Reviewed By: N. Jake Summers, DPM
Residency Program: Mount Auburn Hospital, Harvard Medical School, Cambridge, MA

Podiatric Relevance: Ankle fractures are commonly treated in both orthopaedic and podiatric settings, and can often be associated with accompanying syndesmosis injuries that require concurrent treatment. Syndesmotic injuries are most typically present in cases of Lauge-Hansen pronation-external rotation (PER) and Danis-Weber type C ankle fractures. Current debate about the choice of syndesmosis repair and fixation methods has become increasingly prominent in recent literature when treating ankle fractures with associated syndesmotic disruption. The accuracy and maintenance of syndesmotic reduction is essential in properly treating these injuries for both normal anatomic and mechanical function of the ankle joint. The debate over screw fixation, number of screws, number of cortices, screw removal, and most recently suture button fixation ranges from concerns of strength to accuracy of anatomic reduction. This study aims to compare single screw fixation versus TightRope (Arthrex, Naples, FL, USA) suture-button fixation for accuracy and maintenance of syndesmotic reduction as well as the development of post-traumatic arthritis.

Methods: The authors performed a Level I, single center, prospective randomized controlled trial of 43 adult patients with PER or Danis-Weber C ankle fractures with associated syndesmotic disruption as determined by radiographic stress testing at time of initial presentation. Power calculations based on previous study results of 50 percent malreduction with screws and 5 percent malreduction with suture endo-button fixation, resulting in a minimum sample size of 19 patients per group and a 20 percent dropout rate. Sixty eligible patients were evaluated, and 17 patients were excluded due to study exclusion criteria. Patients were then randomized into either the screw fixation or TightRope fixation groups via a computerized random number generator. Twenty-two patients were randomized into the screw group and 21 patients were randomized into the Tightrope group. After ankle fracture fixation was performed using standard AO principles, the method of syndesmosis fixation was revealed to the surgeon, who then performed reduction and fixation of the syndesmosis via either the assigned screw or Tightrope method. Single screw fixation with a tricortical 3.5mm screw, or single Tightrope endo-button fixation was employed at the distal tibiofibular joint. Reduction of the syndesmosis was confirmed via intraoperative CT scan, and re-reduced/fixated if malreduction was noted intraoperatively and rescanned via CT until anatomic reduction was achieved. The uninjured contralateral limb was evaluated via CT as reference for appropriate syndesmosis reduction. Patients were PWB in a below-knee cast for six weeks, and then advanced to FWB as tolerated without additional bracing. Functional outcomes were assessed at one year and two years postoperatively via Olerud-Molander score, VAS, RAND-36, and FAOS. Final CT scanning was also performed at final follow-up (minimum two years, mean 36 months in Tightrope and 37 months in screw group). Reduction of the syndesmosis was assessed and compared to uninjured ankle for both intraoperative CT scan and final follow up CT scans.  Malreduction was defined as >2mm difference from the uninjured ankle. Osteoarthritis was also assessed at the final follow up via the Morrey-Wiedeman classification (Grade 0, 1, 2, 3, 4) and compared to the uninjured side.

Results: Due to poor CT image quality and patients lost to follow up, 19 patients in the screw group and 21 patients in the TightRope group were analyzed at final follow-up. No statistical difference was noted in overall patient demographics and fracture types. Intraoperative CT scans showed malreduction of one syndesmosis in the screw group (requiring re-reduction/fixation) and seven patients in the TightRope group (which spontaneously reduced intraoperatively when ankle was dorsiflexed to 900). Postoperative CT scan revealed malreduction of the syndesmosis in three patients in the screw group and onepatient in the TightRope group. OA was more common in the injured ankle than the uninjured ankle for both groups, but no significant difference was noted in OA between the two fixation methods. There was improvement in both groups in all functional outcome scores, but no statistical significance was found between the two groups.

Conclusions: With regards to PER and Danis-Weber C ankle fractures with associated syndesmotic injuries, this prospective randomized trial showed that both single screw fixation and TightRope fixation resulted in a low malreduction rate (5 percent), which was maintained at the two year follow-up. Both screw fixation and TightRope fixation of the syndesmosis showed adequate reduction, maintenance of reduction, similar functional outcome scores, and similar post-traumatic OA grades with no significant statistical differences. The use of intraoperative CT scan may not be useful, and was somewhat unreliable in assessing accurate reduction of the syndesmosis via TightRope fixation, with a high false positive rate.  

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