Simplified stress radiography in injured knees to diagnosis of torn anterior cruciate ligaments

Abstract

Objective : To determine the diagnostic value of the simplified stress radiography in diagnosis of torn anterior cruciate ligaments (ACL). Design : A hospital-based prospective cross sectional diagnostic test study. Setting : Siriraj Hospital Patients : Sixty two adult patients aged 18 years or more with soft tissue injury of unilateral knee and planned for knee surgery. Intervention: Each patient underwent a simplified stress radiographic investigation immediately prior to surgery. Knee arthrometry was performed under anesthesia prior to surgery. Arthroscopic knee surgery was performed. Surgical findings of all intraarticular structures, as a gold standard, were recorded. Radiographic measurement and diagnosis of torn ACL were done independently by two blinded radiologists. Results of first radiologist in diagnosis of torn ACL were compared to the surgical findings. Diagnostic properties of this stress radiograph were analyzed. Results of two radiologists were compared to each other for interobserver reliability study. Results: From surgical findings, there were 52 patients with torn ACL and 10 patients with intact ACL. Sensitivity of this simplified stress radiography in diagnosis of torn ACL was 69.23% (95% confidence interval = 55.73 to 80.09). Specificity was 100% (95% confidence interval = 72.25 to 100). Positive predictive value was 100% (95% confidence interval = 90.36 to 100). Negative predictive value was 38.46% (95% confidence interval = 22.43 to 57.47). The interobserver reliability study between to radiologists was calculated by Kappa statistic; Cohen's Kappa was 0.73 (95% confidence interval = 0.56 to 0.90). Conclusion: The diagnostic value of the simplified stress radiography in diagnosis of torn anterior cruciate ligaments was more appropriate for diagnosis confirmation than disease screening.