E2464. Sensitivity and Specificity of the OK Sign for Acute Fractures on Emergency Department Hand Radiographs
  1. Robert Burt; Loma Linda University Medical Center
  2. Erica Kinne; Loma Linda University Medical Center
Traumatic injuries to the hand are a common occurrence, and prompt recognition of injuries that require surgical or nonsurgical treatment is critical for patients to maintain long-term function. Hand fractures occur at an estimated annual incidence of 29 people per 10,000, with an estimated 26 million emergency room visits a year attributed to hand injuries. In the emergency room setting, the radiologist must promptly and accurately recognize a wide array of injuries, and the humble radiograph plays an essential role in this setting. To our knowledge, no prior study has investigated the sensitivity and specificity of the "OK" sign, a sign we are designating to the correctly positioned lateral fan view, where the fingers are flexed and spaced like a fan, and how it relates to the incidence of hand fractures. The goal of this study is to determine the association of the presence or absence of the OK sign with the presence or absence of an acute fracture.

Materials and Methods:
All patients over the age of 18 who underwent hand radiographs for trauma in the emergency room between 4/1/2020 and 4/1/2021 were screened for inclusion in this study. Patients with documented Glasgow Coma Scale score < 14 at time of imaging, quadriplegia, or simultaneous spinal cord injury at time of imaging, or proximal ipsilateral upper extremity injury at time of imaging, exclusive of visualized distal radius and ulna injuries, were excluded. Repeat radiographs within the data collection period were also excluded. Subject age, gender, presence or absence of the OK sign, and presence or absence of fracture were recorded. Chi square and/or Fisher’s exact tests were used to determine statistical significance, and sensitivity and specificity calculations were performed by comparing the presence or absence of the OK sign with presence or absence of a fracture.

A total of 322 men and 182 women were included in the study, with ages ranging from 19 - 100 years old. Fractures were present in 175 (35%) of the included subjects. The OK sign was present in 41 studies with a fracture and 289 studies without a fracture. The OK sign was absent in 134 studies with a fracture and 40 studies without a fracture. Absence of the OK sign was statistically significant for the presence of a fracture (p < 0.001), with a sensitivity of 76% and specificity of 87%.

Absence of the OK sign has a highly sensitive and specific association with the presence of an acute hand fracture in the emergency room setting and should raise the index of suspicion for fracture.