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. 2022 Feb;14(2):341-348.
doi: 10.1111/os.13185. Epub 2021 Dec 22.

Variation in Global Spinal Sagittal Parameters in Asymptomatic Adults with 11 Thoracic Vertebrae, four Lumbar Vertebrae, and six Lumbar Vertebrae

Ying-Zhao Yan  1 , Ben Wang  2 , Xiao-Qin Huang  1 , Xuanliang Ru  1 , Xiang-Yang Wang  2 , Hang-Bo Qu  1
Affiliations

Variation in Global Spinal Sagittal Parameters in Asymptomatic Adults with 11 Thoracic Vertebrae, four Lumbar Vertebrae, and six Lumbar Vertebrae

Ying-Zhao Yan et al. Orthop Surg. 2022 Feb.

Abstract

Objective: To investigate the prevalence of 11 thoracic vertebrae (TVs), four lumbar vertebrae (LVs) and six LVs among asymptomatic Chinese volunteers, and the influence of spine variations on the global spinal sagittal parameters.

Methods: A total of 389 asymptomatic Chinese volunteers were recruited. Each subject underwent a full-spine X-ray examination with measurement of global spinal sagittal parameters. The radiographs were examined by a spine surgeon and a radiologist to determine the variation in the number of vertebrae. These parameters were used to compare individuals with five LVs to those with 11 TVs, four LVs, and six LVs.

Results: The study population included 12 individuals (3.1%) with seven cervical vertebrae (C) + 11 thoracic vertebrae (T) + five lumbar vertebrae (L), 8 (2.1%) with 7C + 11T + 6L, 8 (2.1%) with 7C + 12T + 4L, and 15 (3.9%) with 7C + 12T + 6L. Compared to the 7C + 12T + 5L individuals, those with 7C + 11T + 5L had significantly lower C6 -T5 Cobb values (P < 0.05); 7C + 12T + 4L individuals had significantly greater thoracic inlet angles (P < 0.05) and significantly lower pelvic tilt (P < 0.05); individuals with 7C + 12T + 6L had significantly greater sacral slope, pelvic tilt, pelvic incidence, and L1-5 Cobb values (all P < 0.05), but significantly lower thoracic inlet angle (P < 0.05). There were no significant differences in any of the parameters examined between the 7C + 11T + 6L group and the 7C + 12T + 5L group.

Conclusions: Asymptomatic adults with 7C + 12T + 6L, 7C + 12T + 4L, and 7C + 11T + 5L presented with different spinal sagittal alignment compared to those with 7C + 12T + 5L. Compared to variation in the number of LVs, the variation in the number of TVs had less effect on global spinal sagittal parameters. Spinal surgeons and researchers should be aware of the effects of variation in numbers of TVs and LVs on global spinal parameters and sagittal balance.

Keywords: 11 thoracic vertebrae; Chinese asymptomatic volunteer; Four lumbar vertebrae; Sagittal alignment parameter; Spine variations.

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Figures

Fig. 1
Fig. 1
An example of a unilateral 12th rib to distinguish the poorly developed 12th rib from the first lumbar transverse process. (A) The poorly developed rib could not be viewed in the lateral X‐ray image. (B) A smaller example of a unilateral 12th rib to distinguish the poorly developed 12th rib from the first lumbar rib vertebrae angle (RVA) between the rib and the anterior midline of vertebral body in the posteroanterior view. (C) There was a “lesser rib fossa” at the junction of ribs and vertebrae in the posteroanterior view.
Fig. 2
Fig. 2
Measurement methods of some spinal parameters.
Fig. 3
Fig. 3
Full‐spine X‐ray images of each group.
See this image and copyright information in PMC

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