[Efficiency of the Modified Ottawa ankle rules for the differential diagnosis of fracture in acute foot and ankle injury].

ABSTRACT

Objective: To evaluate the efficiency of modified Ottawa Ankle Rules (OAR) for the differential diagnosis of fractures in acute foot and ankle injuries. Methods: From October 2016 to December 2016, 272cases (135 males and 137 females) of foot and ankle injury in emergency department of Tianjin Hospital were prospective enrolled in the study.The median age was 27.5 years (7-87); left limb 155, right 117 cases; injury time ranged from 0.3 to 24 h (median 4 h). Conventional and modified OAR was applied on physical examination, subsequently radiography performed to determine the occurrence of fractures.The efficiency of the two methods were compared and analyzed. Results: Fractures were found in 100 cases (36.8%), 49 cases of ankle and 51 cases of foot fractures.With the imaging results as the standard, the sensitivity for conventional and modified OAR were 93.0% and 100%, specificity were 9.9% and 8.7%, the positive predictive value were 37.5% and 38.9%, the negative predictive value were 70.8% and 100%, the accuracy were 40.4% and 42.3%, missed diagnosis rate were 7% and 0% respectively.The sensitivity, positive likelihood ratio, positive predictive value, negative predictive value, accuracy, negative likelihood ratio and missed diagnosis ratio were better than in modified OAR compared with Conventional OAR, while the specificity was slightly lower compared to Conventional OAR.The Kappa value of modified OAR was 0.065 (P>0.05), which is better than conventional OAR.Conventional OAR can reduce 6.3% (17/272) X-ray and modified OAR decline 5.5% (15/272). Conclusion: Modified OAR significantly reduces the rate of missed diagnosis of foot fractures, but its specificity is poor. Ultrasound can be assisted to improve the specificity and reduce the number of unnecessary X-rays.