Abstract and Introduction
Abstract
Study Design: Prospective comparative study.
Objective: Refinement of the guidelines for screening of osteoporosis and considering quantitative computed tomography (Q-CT) for detecting spinal osteoporosis.
Summary of Background Data: Spinal osteoporosis is often underestimated and under-evaluated due to either lack of availability of the diagnostic modality or lack of awareness about the possibility of overestimation by dual X-ray absorptiometry (DXA) scan. There is a need for reconsidering osteoporosis evaluation with a site specific and patient specific inclination.
Methods: Post-menopausal women that underwent bone mineral density (BMD) evaluation from January-2018 to December-2020 with either Q-CT or DXA were evaluated. Comparison studies of the distribution of age and T-scores of the bone densities obtained from the two study groups: age-matched, sex-matched, and common skeletal site of interest (L1-4 vertebrae) were performed. Mann–Whitney U test, correlation and regression analyses were performed and bell curves were plotted.
Results: Of the 718 women evaluated, 447 underwent Q-CT and 271 underwent DXA. There was no significant difference among the age distribution of the two study groups (P-value > 0.05). The mean and mode T-scores obtained by Q-CT and DXA were found to be –2.71, −3.8 and –1.63, −1.7 respectively. A highly significant difference in the T-scores was observed in the Q-CT and DXA groups (P-value < 0.0001). Among those who were screened by Q-CT, 58.16% were osteoporotic, 37.58% were osteopenic, and 4.25% were normal. The respective percentages in the DXA group were 30.63%, 49.82%, and 19.55%.
Conclusion: Q-CT provides more precise estimation of cancellous bone mineral density than DXA. With the reliance on DXA for spinal BMD estimation being questionable, new standards have to be established for spinal osteoporosis evaluation. Q-CT can be a better alternative to replace DXA as the gold standard for the evaluation of spinal osteoporosis.
Level of Evidence: 2
Introduction
Precise evaluation of vertebral osteoporosis is critical in the management of spinal disorders. Pedicle screws, the principal workhorses of spine instrumentation, obtain their maximum stability from purchase in trabecular bone.[1,2] Ultimately, the long-term surgical outcomes are highly dependent on trabecular bone stock. Low bone mineral density (BMD) associated with conditions requiring surgical intervention has a prevalence ranging from 30% to 70% in the elderly and post-menopausal women.[3] Although the micro-architectural deterioration of bone tissue in osteoporosis is evident in both cortical and cancellous bones, the latter being metabolically more active has higher bone fragility and susceptibility to fracture.[4] Hence, it is more relevant to concentrate on the trabecular component than the integral BMD for spinal osteoporosis.
Different methods of bone density estimation known are radiographic-absorptiometry (RA), single-X-ray absorptiometry (SXA), dual-X-ray absorptiometry (DXA), spinal and peripheral quantitative computed tomography (Q-CT and pQ-CT), opportunistic CT-chest/abdomen evaluation, and quantitative ultrasound (QUS).[5] There is a wide gap between the established standards considering DXA as a gold standard for bone density estimation[4,6] and the research activity and technological advancements in the form of finite element analyses—comparing the biomechanics of different fixation options available and various augmentation techniques evolved.[7] It is surprising that the well-known drawbacks of DXA and the availability of newer and better modalities for screening of spinal osteoporosis have not changed the standards of practice. There is a need for reconsidering osteoporosis evaluation with a site specific and patient specific inclination. This study aims at suggesting refinement in guidelines for screening of osteoporosis and considering Q-CT for detecting spinal osteoporosis as standard of care.
Spine. 2022;47(6):E258-E264. © 2022 Lippincott Williams & Wilkins
