Visual versus quantified digital radiographic determination of bone density.
Quantitative digital radiography (QDR) was used to assess the ability of physicians to determine bone mineral density (BMD) loss from a series of plain radiographs.  Twenty-four spinal cord injured patients underwent QDR of the left knee.  Seven of the 24 were selected, each of whom had bone mineral loss from 10-70% in 10% increments as assessed by comparison to average BMD of age-matched controls, and a standardized AP radiograph of the left knee was performed. Twenty-five independent examiners (orthopaedic surgeons and residents) were then asked to view the randomly arranged radiographs and visually determine the amount of BMD loss for each radiograph as compared to a control radiograph at 100%.  Chi square analysis of the data revealed that the distribution of responses was significantly different than expected at the p less than .01 level.  Taking into account that responses may have erred by +/-10%, the distribution of responses was again found to be significant at the p less than .01 level. An accurate determination of BMD loss was achieved only at 10% bone loss and 70% bone loss.  The results of this study suggest that the visual determination of bone loss based on plain radiographs is accurate only at very low or very high levels of bone loss.  Using standardized techniques, only near normal radiographs or radiographs with at least 70% BMD loss can be assessed accurately.
Spinal Injury Service, Rancho Los Amigos Medical Center, Downey, California.
D E
DE
Garland
K
K
Lewonowski
R H
RH
Adkins
C A
CA
Stewart
D015519:Bone Density; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D015588:Observer Variation; D010024:Osteoporosis / Q000150:complications / Q000000981:diagnostic imaging*; D011856:Radiographic Image Enhancement; D012680:Sensitivity and Specificity; D013119:Spinal Cord Injuries / Q000150:complications / Q000000981:diagnostic imaging