SLR - September 2018 - Calvin J. Rushing

Arthroscopically Measured Syndesmotic Stability After Screw vs. Suture Button Fixation in a Cadaveric Model

Reference: Lubberts B Vopat BG, Wolf JC, Longo UG, DiGiovannie CW, Guss D. Arthroscopically Measured Syndesmotic Stability after Screw vs. Suture Button Fixation in a Cadaveric Model. Injury, Int. J. Care Injured 48 (2017) 2433–2437.

Scientific Literature Review

Reviewed By: Calvin J. Rushing, DPM 
Residency Program: Westside Regional Medical Center, Plantation FL
Podiatric Relevance: In recent years, syndesmotic fixation constructs have become the subject of an increasingly contentious debate, with purported advantages for both quadricortical screw and suture button fixation. The stability imparted by these constructs relative to the native, uninjured syndesmosis, however, remains poorly understood.     

Methods: A level V cadaveric study was performed on eight matched pairs of above-the-knee specimens to arthroscopically assess the stability of the ankle syndesmosis following screw versus suture button fixation. Measurements were performed on the specimens under four states: an intact state, a disrupted state simulated by sectioning of the anterior inferior tibiofibular ligament (AITF), interosseous membrane (IOM), posteroinferior tibiofibular (PITFL) and deltoid ligaments (superficial/deep), and a repaired state, following the insertion of a quadricortical syndesmotic screw or suture button. For each state, unstressed and stressed conditions were simulated with an applied force of 100N, 5 cm proximal to the ankle from medial to lateral, anterior to posterior and posterior to anterior. The coronal plane diastasis and sagittal plane translation of the ankle syndesmosis were assessed arthroscopically and measured at the anterior and posterior third of the incisura using probes of increasing diameter (range 0.1 mm to 6 mm, 0.1 mm increments).

Results: Quadricortical screw fixation resulted in similar coronal plane diastasis compared to the ankle syndesmosis’s native state but significantly less sagittal plane translation (p = 0.012). Suture button fixation also resulted in coronal plane diastasis comparable to the uninjured, intact state; however, significant sagittal plane instability persisted (p = 0.012). Between the two fixation constructs, no significant differences were demonstrated regarding the stability imparted in the coronal plane (p = 0.72). However, the difference between the sagittal plane stability imparted was statistically significant (p = 0.012).  

Conclusions: Based on the results of this study, neither quadricortical screw or suture button fixation appeared to provide the stability of the native, uninjured ankle syndesmosis. Quadricortical screw and suture button fixation resulted in an excessively constrained and unconstrained state of the fibula within the tibial incisura, respectively, in the sagittal plane.

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