Natalie Black, Dr. Jie Chen
University of Texas Medical Branch School of Medicine
Intro: Obtaining cadaveric bone mineral density (BMD) via dual energy X-ray absorptiometry (DEXA) is routine in orthopaedic biomechanical research studies. However, DEXA scans can be costly, time-consuming, or not readily available at some institutions. “Matched pairs” are often used in such studies to further equalize comparison groups assuming similar bone morphology and quality. It has been shown that BMD of cadaveric specimens affects construct fixation strength but other studies show DEXA scans do not correlate well with biomechanical bone strength in cadavers. Given the widespread use of matched pair analysis, the practicality of obtaining routine DEXA scans remains unknown. The purpose of this study was to determine the value of DEXA scans in biomechanical cadaveric studies. Methods: We identified 10 sequential journal articles from the Journal of Orthopaedic Trauma from February 2019 to February 2013 that were biomechanical studies with 2 comparison groups that used matched pairs DEXA scanned prior to experimentation. We extracted data concerning: Number of pairs used, pairs discarded, and significant difference in BMD or T score between groups. Results: 113 matched pairs were reported with zero reports of discarded specimens due to DEXA results. 5 studies reported BMD as their unit of measurement, 2 reported T score, and 3 used both. T score or BMD was compared between specimens grouped by laterality in 5 studies, by treatment in 4, and by both separately in 1. No studies reported significant statistical difference in T score or BMD between specimen groups regardless of grouping. No studies disclosed BMD or T score for any individual specimen or score difference for any individual pair. Conclusion: In no instance did DEXA scanning of matched pairs reveal a significant difference in BMD or T score of comparison groups and no samples were discarded due to unequal scores. There was discrepancy in reporting DEXA results and the grouping of compared specimens. No transparency of individual specimen DEXA scores existed. These results indicate there may be no significant benefit in obtaining routine DEXA scores in biomechanical cadaveric matched-pair analyses given the increased time, cost, and notably when testing results are not analyzed by bone density. Also, there should be greater uniformity and transparency in the literature when reporting DEXA scores, and if obtained, consideration should be given to discarding pairs with unequal bone density
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