Location Matters in Syndesmosis Screw Breakage: Interosseous Breakage and Breakage Location Within the Tibia Affect Rates of Removal Secondary to Pain

Abstract

Category: Ankle; Ankle; Trauma Introduction/Purpose: Broken or loose syndesmotic screws are typically reported to be clinically asymptomatic, however, screw breakage can lead to significant pain depending on location. Syndesmosis screws that span the incisura are particularly at an increased risk for painful outcomes. In patients with intraosseous screw breakage, normal physiologic translation where the distal convex of the fibula fits into the concave tibial incisure can lead to painful bony erosion overtime. The purpose of this investigation is to assess variables that my predict location of syndesmosis screw breakage and to also assess the effect of screw breakage location on eventual removal secondary to pain. Methods: A retrospective analysis of 1,056 patients who underwent syndesmosis fixation revealed 88 patients (121 screws) who experienced pst-operative syndesmosis screw breakage and met predetermined inclusion criteria. Patient demographic data, BMI, comorbidities, pain scores, complication rate, and revision rate were all collected. Screw length, width, number, placement height above the tibial plafond, angle, location of breakage, breakage distance location on the screw and implant removal secondary to pain were also collected. A series of binomial logistic regressions were performed to ascertain the effects of the collected variables on the likelihood of breakage location and removal secondary to pain. Regression analysis included intraosseous versus clear space breakage, tibia versus fibula breakage, and removal secondary to pain in each breakage location group (tibia, fibula, clear space). Results: Of the 121 broken screws, 91 (75.2%) broke within an intraosseous (IO) location (68 patients, 77.3%). Twenty-eight screws (23%.1) (18 patients, 20.5%) broke exclusively within the clear space (CS). Sixty screws (52 patients, 59.9%), had IO breakage within the tibia, while 29 screws (24 patients 27.7%) had breakage within the fibula. Two screws (2 patients, 2.27%) occurred within an intraosseous location and the clear space. Intraosseous screw breakage was associated with higher risk removal secondary to pain (P=.020). Multiple screw usage associated with an increased risk for CS breakage (P =.012). IO and CS screw angle and placement had no effect on screw breakage location (P =.629, P =.570). Screw breakage closer to the CS (P=.001), increased number of screws used (P=.003), and higher patient pain scores (P =.003) were associated increased risk of removal due to pain within the IO tibia breakage group. Conclusion: Syndesmotic screw breakage location plays a more important role than previously reported. When compared to clear space, intraosseous breakage is associated with increased rates of removal due to pain. Breakage location within the tibia occurring closer to the clear space is associated with higher rates of removal secondary to pain and higher patient report pain scores. Usage of multiple screws was found to be the only significant predictor of clear space vs intraosseous breakage; all other variables were found to be non-contributary, including no appreciated significance of screw placement in relation to the tibial plafond or screw angle.