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Objective:
Lower back pain is a major cause of disability and medical expenditure. At many institutions, the routine lumbar radiographic exam includes three views: AP, lateral, and coned-down lateral of the lumbosacral junction. The purpose of this study is to determine whether the coned-down lateral view adds significant diagnostic information regarding pathology at the L4-L5 and L5-S1 levels.

Materials and Methods:
This retrospective study includes patients who had a three-view radiographic exam of the lumbar spine, as well as a CT or MRI within 6 months. The AP and lateral views were reviewed by three radiologists, both with and without the use of the coned lateral view, with attention to alignment and disc disease. The reviews occurred in separate settings to ensure blinding. Confidence in diagnosis and quality of the coned-down view were also noted. Subsequently, the CT and MRI examinations performed within six months was reviewed, and the results compared. Statistical analysis was performed with the binomial test.

Results:
The study cohort (n = 74) consisted of inner-city Bronx patients with a median age of 56 years, BMI of 29, and 72% women. Spondylolisthesis was identified on 16 (22%) of two-view and 14(19%) of three-view examinations. On the two-view examination, disc disease was identified on 32 (43%) of examinations at L4-L5 and 15 (20%) of examinations at L5-S1. With addition of the third view, disc disease was identified on 30(41%) of exams at L4-L5 and 19(26%) of exams at L5-S1. On CT/MRI performed within 6 months, spondylolisthesis was present on 25(34%) of exams; disc disease was present on 31(42%) of exams at L4-L5 and 19(26%) of exams at L5-S1. For any scored radiographic abnormality, there was disagreement between two-view and three-view examinations on 18 (out of 296) evaluations. Of these 18, positive findings were made on nine of each of the two- and three-view examinations. According to the binomial test, there is no evidence that either the two-view or the three-view examination agrees on 75.3%. Therefore, there is no evidence that the three-view examination is more accurate than the two-view examination. Radiologist self-perceived confidence in diagnosis was increased from 87% to 97% with the addition of the third view. The quality of the coned-down lateral view was noted to be suboptimal in 49% of exams due to FOV and/or obliquity.

Conclusion:
In our study of a diverse population, the addition of a coned-down lateral view did not contribute to more findings or increased accuracy in assessment of alignment or disc disease. Additionally, the quality of the coned-down view was often suboptimal. As expected, the additional view adds significant radiation exposure. Interestingly, the addition of the third view increases radiologist self-perceived confidence, which could contribute to the performance of three-view examinations at many institutions. Elimination of the coned-down lateral view in the lumbar radiograph series could reduce radiation exposure to patients and imaging-related costs while maintaining diagnostic quality in evaluation of the lumbosacral junction.