Utility of conventional radiographs in the detection of traumatic knee arthrotomies: a retrospective cohort review

Abstract

Background: The most common method to determine a traumatic knee arthrotomy is the saline load challenge. Recent literature has suggested high false-negative and false-positive rates using this method and also has shown that CT was effective in detecting these arthrotomies. The purpose of this study was to evaluate another method of diagnosing these injuries. We hypothesized that plain radiographs of the knee could be an effective alternative study in diagnosing a traumatic arthrotomy. Methods: After institutional review board approval, this retrospective cohort review identified 32 patients diagnosed with a traumatic arthrotomy by direct visualization in the operating room and another 32 patients with no evidence of traumatic arthopathy, according to the surgeon. The preoperative anteroposterior and lateral radiographs from both cohorts were blinded and randomized and then submitted to a radiologist to review for the presence of air in the joint space. Sensitivity and specificity were calculated based on radiographic review compared with the gold standard of direct visualization. Results: Plain film anteroposterior and lateral knee radiographs had a sensitivity of 78.1% and a specificity of 90.6% with a positive predictive value of 89.3% for diagnosis of traumatic arthrotomy in our cohort. Conclusions: Our study suggests that radiographs, which are obtained as standard of care during work-up of knee injuries, have a relatively high sensitivity and specificity and can be used as an adjunct to help diagnose a traumatic arthrotomy of the knee joint. Level of Evidence: Level III.