Does Surgical Placement of Syndesmosis Screws Affect Breakage Rate? A Retrospective Comparative Study

Abstract

Category:AnkleIntroduction/Purpose:Fixation of syndesmosis disruption with metal screws remains a frequent and efficacious treatment modality. Screw breakage remains a complication seen in many patients following metal fixation. Overtime physiologic rotation or the tibia and fibula can lead to bone erosion and pain in patients with screw breakage. The purpose of this study is to compare patients with syndesmosis screw breakage and patients with intact screws based surgically controlled variables.Methods:A retrospective analysis of patients who underwent syndesmotic screw fixation from 2008 - 2020 was performed. Ninety-seven patients were found to have syndesmosis screw breakage, of which 88 met inclusion criteria. A control group of patients without syndesmosis screw breakage was selected at random and analyzed until 88 patients met inclusion criteria. The number of screws used, width, length, fracture type and number of cortices were all collected. Further analysis included radiographic measurement syndesmosis screw angle and height of placement above the tibial plafond. A regression analysis was performed to compare to the two groups, including a separate analysis comparing unbroken screws within syndesmosis screw breakage cohort versus their broken screws, as this provided an absolute control group. A stratified analysis of screw placement and angle was also performed based on standard deviation.Results:The average screw width in the breakage group was 3.67 (SD =.38) and 4.06 (SD =0.04) in the intact group (P =<.001). Average screw angle was 94.82 (SD = 12.75) in the breakage group and 94.67 (SD 12.31) in the intact group (based on 90 degrees relative to tibial plafond). Screw placement of the tibial plafond was 20.39 (SD =10.389) in the breakage group and 16. 75 (SD = 9.28) in the intact group. 70.3% of broken screws were placed > 20mm above the tibial plafond, compared to 64.0% in the control group. Most screws were placed at angle > 82 degrees relative to the tibial plafond; 76% (n =92) of broken screws and 81.2% (n=211) of intact screws). Decreased screw width (P =<.001) and screw placement > 20mm above the tibial plafond (P =<.001) were all associated with an increased risk of screw breakage.Conclusion:Metal screw fixation remains an efficacious treatment method of syndesmotic disruption. Despite extensive research the cause of syndesmosis screw breakage and the necessity of screw removal remains without consensus. The is study aims to analyze surgical variables in attempt to find correlation with screw breakage. An increased BMI was seen to predispose to screw breakage. Placement of the syndesmosis screw <20 mm above the tibial plafond and increased screw width provide protection against syndesmosis breakage. No significant differences were found between groups based on screw angle, number of cortices, screw length, or number of screws used.