SLR - January 2020 - Logan H. Mitchell
Reference: Andersen MR, Diep LM, Frihagen F, Castberg Hellund J, Madsen JE, Figved W. Importance of Syndesmotic Reduction on Clinical Outcomes After Syndesmosis Injuries. J Orthop Trauma. 2019 Aug;33(8):397-403.Scientific Literature Review
Reviewed By: Logan H. Mitchell, DPM
Residency Program: Kaiser SF Bay Area Foot and Ankle Surgery – Oakland, CA
Podiatric Relevance: Syndesmotic injury treatment is a highly debated topic amongst foot and ankle surgeons. Traditionally, syndesmotic injuries were fixated with syndesmotic screws, however there is a current trend toward flexible fixation creating anatomical syndesmotic reduction compared to the contralateral limb. This study associates post-operative clinical outcomes with syndesmotic reduction quality. Additionally, it argues for evaluating the contralateral limb using a CT scan to better assess the patient’s syndesmotic anatomy.
Methods: Author’s performed a cohort study (N=97) of patients who were treated for a syndesmotic injury. Patients were randomized into two groups; the first group received suture button fixation (TightRope, Arthrex) and the second group received one quadricortical 4.5 millimeter screw (all syndesmotic screws removed at 10-12 weeks post-operatively). CT scans of bilateral ankles in neutral position were performed within two weeks, one year and two years postoperatively. The tibiofibular distance was measured at three different points: anterior (aTFD), central (cTFD) and posterior (pTFD) and distances were compared at each time point to the non-operative limb. Interobserver reliability for CT scan measurements were tested. Clinical outcome scores were the Olerud-Molander Ankle (OMA) score and AOFAS score, and were tested at the six-week, six-month, one-year, and two-year marks. Additionally, patients underwent postoperative range of motion measurements (ROM). The impact of CT measurements on clinical outcomes and ROM was examined using linear regression and receiver operating characteristic (ROC) curve analyses were performed to evaluate the utility of CT scan measurements.
Results: A 1 millimeter increase in aTFD was significantly correlated with lower OMA and AOFAS scores on initial postoperative, one-year, and two-year follow up. For cTFD, a correlation was found only at two-year evaluation and no correlation was detected for pTFD. ROM testing showed a significant correlation between cTFD and pTFD at six weeks and found a significant correlation between aTFD and ROM at two years. Method of syndesmotic fixation and BMI had a significant effect on outcome scores. ROC curve analyses showed that aTFD demonstrated acceptable discriminatory performance at all timepoints. Interobserver rates of reliability ranged from moderate to almost perfect. Using an aTFD > 1.0mm as a test for inferior clinical outcome, sensitivities and specificities ranged between 50 percent to 80 percent. The overall malreduction rate was 32 percent.
Conclusions: Significant correlations were found at varying time points for both aTFD and cTFD, however aTFD showed the most significant and consistent correlation with functional outcome. Syndesmotic fixation method was correlated with postoperative outcome, however the paper did not elucidate which fixation method was associated with poor outcomes. This study provides evidence that anterior malreduction of the syndesmosis is closely associated with poor postoperative clinical outcomes. Additionally, it shows that aTFD can be somewhat reliably used to predict clinical outcomes. This study did have several weaknesses. Although syndesmotic reduction was defined at 3 differing levels, it was only defined in the axial plane, excluding fibular rotation and length. Additionally, CT scans were performed in neutral position which may not simulate full weight-bearing.