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.