SLR - December 2020 - Jacob Jones

Patterns and Implications of Early Syndesmotic Screw Failure in Rotational Ankle Fractures

Reference: Behery OA, Mandel J, Solasz SJ, Konda SR, Egol KA. Patterns and Implications of Early Syndesmotic Screw Failure in Rotational Ankle Fractures. Foot & Ankle International.  2020: 41(9): 1065-1072. 

Level of Evidence: III Retrospective Case Control Study

Scientific Literature Review

Reviewed By: Jacob Jones, DPM
Residency Program: West Penn Hospital – Pittsburgh, PA

Podiatric Relevance: Rotational ankle fractures are commonly treated among foot and ankle surgeons. Syndesmotic injuries occur with approximately 1/5 of these injuries and are associated with greater risk for poor clinical outcomes including healing and post-injury function. Historically, these injuries have been treated with open reduction and internal fixation of both the osseous injuries and the syndesmotic rupture. However, the physiologic motion of the syndesmosis inherently creates complications including screw loosening and/or breakage, malreduction, and tibiofibular synostosis. Numerous studies have evaluated the treatment of syndesmotic injuries in an effort to minimize these complications and improve post-operative outcomes, however, limited literature describes the frequency or patterns of syndesmotic screw failure and associated clinical outcomes. This study may provide better insight to these patterns by comparing patients with syndesmotic screw failure to those without syndesmotic screw failure. 

Methods: This study was a retrospective case control study of 169 patients that underwent open reduction and internal fixation with an associated trans-syndesmotic screw. Fifty-six patients had trans-syndesmotic screw failure while 113 patients had intact trans-syndesmotic screw. Postoperative radiographs were reviewed for number of cortices, screw breakage and location, and tibio-fibular overlap. Clinical outcome was identified through clinical examination of ankle range of motion and Maryland Foot Score. 

Results: On average patients with trans-syndesmotic screw failure were statistically younger, predominantly male, and had a slightly lower ASA rating. Additionally, the failure group had a higher proportion of pronation external rotation and suprasyndesmotic injuries, however, this was not statistically significant. The majority of screw breaks occurred at the distal tibial metaphysis, followed by the fibula and less commonly in the incisura. When multiple screws were placed the most proximal screw was most likely to break, however, both proximal and distal screws broke in 1/3 of patients. Twenty-three percent of patients with a single screw had breakage compared to 44 percent of patients with two-screw fixation. Thirty-one percent of patients with tri-cortical screw fixation experienced breakage compared to 16 percent of patients with tetra-cortical screw fixation. No patients experienced late syndesmotic widening. Clinically, patients with screw breakage experienced longer follow up and screw removal; however, ankle range of motion and Maryland Foot Scores were similar between the two groups. 

Conclusions: This study was able to identify patient characteristics and fixation techniques as risk factors for early trans-syndesmotic screw failure. The study shows increased likelihood of screw failure in younger male patients. They contribute this to these patients being more active and ambulatory in the early post-operative period compared to older patients. The study shows lower rates of screw failure with tetra-cortical fixation when compared to tri-cortical fixation; however, did not find a correlation between size of screw fixation which has been identified in previous studies. Finally, this study found that anatomically screw failure is most likely to occur at the distal tibial metaphysis and least likely to occur in the incisura. Knowledge of these patterns can help foot and ankle surgeons educate their patients in the pre- and post-operative period regarding such complications and its effect on clinical outcomes. 

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