无柄髕关节是少量应力遮挡的人工髕关节(续)

3 少量应力遮挡的人工髕关节(low stress shielding arthroplasty of the hip)从生理学而言,股骨颈尤其重要,因为人体相关的生物力学主要压应力,主要拉应力,次要压应力,次要拉应力,及大隆间应力共有五道应力,在股骨头颈间汇总后,在股骨颈内交叉后走向股骨干内外侧皮质骨.

Objective:　To observe pressure changes in the spinal canal of the vertebrarium subjected to impact. From the point of view of impact, pressure changes and spinal cord injuries, the relationship between the type of spinal fracture and the severity of spinal cord injuries were analyzed and some experimental data were provided for early evaluation of severity of spinal cord injuries. 　　Methods:　An experimental model of spinal burst fracture was made with Type BIM-I bio-impact machine and techniques of high velocity vertical loading in static pattern and stress shielding were adopted. Vertebral sections T10-L4 taken from fresh cadavers were impacted and pressure changes in the spinal canal were observed. The types and severity of spinal fracture were studied with gross and radiography examination. 　　Results:　Great positive pressure wave (wave A) in the spinal canal of the 4 vertebral specimens with burst fracture was recorded. The peak value of pressure was correlated with the severity of posterior column injuries. Generally, the peak value of pressure was low in the samples with posterior column injuries, but high in the samples without injuries. The predominant features of fractures were burst fractures of vertebral body and severe destruction of the skeletal and fiber structure of the spinal canal. Positive and negative pressure waves (wave B) were recorded in 2 vertebral samples in which no significant abnormal changes were found by radiography examination, however, a little liquid effusion in the vertebral body was found by gross examination. 　　Conclusions:　The type of pressure wave in the spinal canal is related to the deformation or the destruction of the spinal canal structure. The peak value of the pressure is non-linearly related to the obstruction in the spinal canal, but related to posterior column injuries.