115 A Retrospective Review of the Clinical Significance of Knee Effusions on X-ray Imaging and the Relation to Occult Tibial Plateau Fractures

Abstract

Tibial plateau fractures can be difficult to visualize on x-rays and in the absence of routine use of advanced imaging modalities such as CT or MRI, they can be missed. Diagnosing this fracture early is critical and the delay in treatment can result in the tibia remaining in a subluxed position. This can lead to abnormal loading on the joint, resulting in early degeneration, deformity, and limitation of knee movements. The primary objective of this study was to determine if there is a correlation between effusions viewed on initial knee x-ray and occult tibial plateau fractures. Secondary objectives evaluated for associations between fractures and patient demographics, mechanism of injury, co-morbidities, and surgery rates. This was a retrospective chart review conducted at a tertiary academic hospital with 64,000 annual ED visits and a second satellite facility with nearly 30,000 ED visits. ICD10 coding were used to extract all patients from the electronic medical record from 9/1/2012 to 6/30/2019, with the diagnosis of tibial plateau fracture. The medical records were individually reviewed for the presence of tibial plateau fractures and the imaging obtained. Specifically, the presence or absence of knee effusions on x-rays, in which the fracture was not initially seen, but subsequently confirmed on CT or MRI. Additional recorded information included patient demographics, trauma activations, surgery rates, fall from a height, and co-morbidities. Descriptive statistics were used to summarize demographic and clinical characteristics of the patients. Fisher’s exact test was used to look at the association between diagnosis of fracture from plain x-ray and detection of effusion on x-ray. Additional analysis was done to look at the association of patient demographics with need for surgery. Results were reported as odds ratios and 95% CIs. Analyses were done using SAS, Version 9.4. P<0.05 was considered statistically significant. 321 tibial plateau fracture identified per x-ray, CT, or MRI. 50% were female and the mean age was 53 years old. There were 84 occult fractures, which by definition, did not reveal fracture on x-ray but ultimately confirmed on CT or MRI. There was a statistically significant association between the presence of an effusion and non-occult tibial plateau fracture (OR: 2.93, 95% CI: 1.20, 7.19; p=0.019). Statistically significant predictors of undergoing surgical repair included male sex (OR: 2.91, 95% CI:1.70, 5.01; p=0.0001), fall from a height (OR: 3.66, 95% CI:2.14, 6.26; p<0.0001), and fracture visualized on the initial x-ray (OR: 10.66, 95% CI:5.17, 21.98; p<0.0001) The presence of an effusion on initial x-ray is more predictive of a non-occult tibial plateau fracture versus an occult one. Individuals of male sex, suffered injury due to fall from a height, or the fracture was visualized on the initial x-ray, were more likely to undergo surgical repair for their tibial plateau fracture.