The bone-hardness distributions of the human middle-upper thoracic vertebrae by micro-indentation / 中华骨科杂志

ABSTRACT

Objective:To measure and analyze the distribution characteristics of the micro-hardness of the middle-upper thoracic vertebrae (T 1-T 10) in the human body. Methods:T 1-T 10 vertebrae from three fresh cadavers were divided into vertebral body area and attachment area. 3 mm specimens were cut by a high-precision slow saw and 11 regions were selected and measured on each vertebrae by a Vickers microhardness tester (cortical bone 1-9, cancellous bone 10-11). The micro-hardness distribution of T 1-T 10 vertebrae was recorded and analyzed. Results:A total of 330 measurement areas from 30 vertebrae were measured, and 1 650 hardness values were collected. The average hardness values of the overall cortical bone of the middle-upper thoracic vertebrae of the 3 cadavers were 30.55±5.44 HV, 29.94±4.86 HV, and 29.55±4.36 HV, respectively. The difference among the groups was statistically significant ( F=4.680, P=0.009). The average hardness values of the overall cancellous bone were 27.93±5.61 HV, 28.21±4.96 HV, 27.98±3.94 HV, respectively. There was no significant difference among the groups ( F=0.091, P=0.913). There were statistically significant differences between the hardness values in the attachment area and vertebral body area of each cadaver ( t=7.467, 4.750, 6.621, P<0.001); the hardness of the cancellous bone in the attachment area of each cadaver was higher than that of the cancellous bone in the vertebral body ( t=1.785, 3.159, 3.103, P=0.077, 0.002, 0.003). The distribution of microhardness in 11 measurement areas of 3 cadavers were similar the hardness of the cortical bone of pedicle, lamina and inferior endplate cortex (1, 2, 7) were higher; the hardness of the cortical bone of upper endplate and peripheral cortex (6, 8, 9) were lower. The distribution patterns of the microhardness in different vertebral segments of the 3 cadavers were similar The hardness values gradually increased from T 1 to T 10. The vertebra with the largest hardness of the cortical bone was T 8; and the vertebra with the largest hardness of the cancellous bone were T 7, T 7 and T 6, respectively. Conclusion:The hardness of the upper endplate and peripheral cortex was low, which could disperse the load to protect the fragile cancellous bone. The hardness of the pedicle was the highest. The hardness of the cortical bone was higher than that of the cancellous bone, and the values of different segments gradually increased from top to bottom, which may be related to the physiological and anatomical morphology, and the gradual increase of the load of muscle force and body weight.