MRI Measurement Of Lumbar Nucleus Pulposus And The Improved Assumption Of Prosthetic Disc Nucleus

Objective:To prevent the existing complications of lumbar nucleus pulposus replacement, The author use the data measured by the MRI T2-weighted image of lumbar nucleus pulposus to propose a assumption based on the existing lumbar prosthetic disc nucleus.Methods:From May 2009 to September 2009. The transverse diameter, sagittal diameter, height of the nucleus pulposus and intervertebral angle of the relatively normal nucleus pulposus of 42 patients were measured in Qilu Hospital's MRI room at the Shandong University. The nucleus pulposus height and intervertebral angle were measured by using middle sagittal intervertebral images. The transverse and sagittal diameters of nucleus pulposus were measured by using the intervertebral axial images. The nucleus cross-section is sub-elliptical, Use ellipsoidal Volume formula to calculate the volume of nucleus pulposus. The mainly improvement is the shape and angle on the basis of the existing lumbar prosthetic disc nucleus.Results:The measurement results were analyzed by using SPSS13.0 statistical software:①The comparison with the different segment of the nucleus pulposus' transverse diameter, sagittal diameter, height and volume and intervertebral angle from L1/2 to L5/S1 segments were analyzed by using LSD(the least significant difference)t-test(P=0.05):the transverse diameter and the sagittal diameter of nucleus pulposus were gradually increased from L1/2 to L3/4 and were gradually reduced from L4/5 to L5/S1. The central height of the nucleus pulposus was gradually increased from L1/2 to L4/5, L5/S1 was slightly small. The volume of nucleus pulposus was gradually increased from L1/2 to L3/4 and was gradually reduced from L4/5 to L5/S1. The intervertebral angle from L1/2 to L5/S1 was gradually increased.②The comparison with the same segment and different gender was used independent samples t-test(P=0.05):The sagittal diameter of L1/2 and L2/3 has statistical difference between male and female, the others segments have no statistical difference. The transverse diameter of L2/3 and L3/4 has statistical difference, the others segments have no statistical difference. The nucleus volume of L2/3 and L3/4 has statistical difference, the others segments have no statistical difference. The height of L4/5 and L5/S1 has statistical difference, the others segments have no statistical difference. The same segment of intervertebral angle has no statistical difference③The comparison with the normal nucleus was used independent samples t-test(P=0.01):the transverse diameter of L5/S1 has statistical difference, the normal nucleus are larger, the others segments have no statistical difference, The sagittal diameter from L2/3 to L5/S1 has statistical difference, the normal nucleus are larger.Conclusions:①The L1/2 segment is not suitable for lumbar prosthesis disc nucleus replacement because L1 is the lower edge of the spinal cord.②The same segment, different genders, the same gender, different segments, the different gender, different segments need different sizes of prosthetic disc nucleus.③The L2/3 segment is suitable for a frontal arched prosthetic disc nucleus with an average angle of 5.59 degrees, L3/4 segment is suitable for a frontal arched prosthetic disc nucleus with an average angle of 6.71 degrees, L4/5 segment is suitable for a frontal arched prosthetic disc nucleus with an average angle of 9.85 degrees, L5/S1 segment is suitable for a frontal arched prosthetic disc nucleus with an average angle of 12.30 degrees.④According to different gender and different segments, the height of the Prosthetic Disc Nucleus should be designed at least five specifications with 5,6,7, 8,9 mm.⑤The data measured of this group can not be considered to be normal nucleus measurements.