Development of Hybrid Testing Apparatusor Dynamic Spine Stabilizer
Date Issued
2008
Date
2008
Author(s)
Wang, Chau-Ho
Abstract
ABSTRACTbjective. To establish a hybrid testing apparatus that provides “moment-control mode” and “angular-displacement-control mode”. The effect of the rod stiffness and that of the rod length on a prototype of dynamic stabilizer (PDS) were investigated using the current testing apparatus. ummary of Background Data. Dynamic spine stabilizer is a newly developed method to diminish the prevalence of early degeneration in adjacent levels. To estimate the effect of dynamic spine stabilizer, it is necessary to establish a testing apparatus.ethods. Using the established testing apparatus, a prototype of dynamic spine stabilizer（PDS）was tested on a cadaver lumbar spine (L1-L4). Following the hybrid testing protocol, the specimen was applied with a sagittle bending moment of 8Nm to obtain the range of motion (ROM) of the whole specimen (tROM_intact) and the ROM of each individual level (iROM_intact) included in the whole specimen. The L2-3 intervertebral disc was damaged at the outer anular fibrosus using a scapal, and then implanted with Dynesys and the PDS. The specimen was sagittaly bended to the ROM which was obtained with the application of 8Nm in the first place. The ROM of each individual level (iROM_construct) was measured simultaneously. The hybrid testing protocol was repeated while the PDS was replaced with other rods of with different stiffness and different length. esults. The angular measured precision of the current apparatus is ±0.12°.The precision of system in“moment-control mode”and“angular-displacement-control mode”is 0.5Nm and 0.2° .Dynesys restored the stability of the injuried L2-3 by 51.1%. The ROM of L1-2 (upper adjacent level) decreased by 42.5% and the ROM of L3-4 (lower adjacent level) was increased by 42.3%. The change of ROM of each individual level after implantation of PDS was in the similar pattern to that of Dynesys, with L2-3 decreased 21.5%，L1-2 decreased 55.7%，and L3-4 increased 22.8%. The stability of the L2-3 was increased with higher rod stiffness and shorter rod length. onclusion. A hybrid testing apparatus that is able to perform hybrid testing protocol is successfully developed. Using the established testing apparatus, the present study reveals that 1) Dynesys reduced more ROM of damaged level than the PDS does, but increased the risk of early degeneration in the lower adjacent level; 2) the efficiency of the PDS can be improved by the rod with higher stiffness and shorter length. Keywords】hybrid testing protocol、Dynesys, dynamic spine stabilizer
Subjects
hybrid testing protocol
Dynesys
dynamic spine stabilizer
Type
thesis
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