Study of Axonal Regeneration in Terminolateral Neurorrhaphy of the Tibioperoneal Nerve in Rats / 대한정형외과학회잡지

PURPOSE: The purpose of this study was to compare the degree of axonal regeneration between end-to-end and terminolateral neurorrhaphy, and determine the degree of nerve regeneration for each method of terminolateral neurorrhaphy. MATERIALS AND METHODS: Thirty-two Sprague-Dawley rats (N=64) were divided into four experimental groups: End-to-end neurorrhaphy (Group 1), end-to-side neurorrhaphy without removal of the epineurial sheath (Group 2), with an epineurial window (Group 3), and with an epineurial window combined with tibial motor axonotomy (Group 4). Each group were sacrificed after needle electromyography at 2, 4, 8, and 12 weeks and transmission electron microscopy was performed to observe the histologic findings of coaptation sites. The weights of tibialis anterior muscles were measured. RESULTS: The amplitude of the compound motor action potential was always lowest in group 4, and there was no statistically significant difference between groups 2 and 3 in terms of the ratio of myelinated to non-myelinated nerve fiber. However, there was a statistically significant difference between groups 2 and 3 in terms of the thickness of the myelin sheath. The tibialis anterior muscle weight in Group 1 increased more so than in the other groups and there was statistically significant difference between group 1 and 4. CONCLUSION: End-to-end neurorrhaphy is the best method of nerve repair, and there was no statistically significant difference between epineurial and epineurial window coaptation in end-to-side neurorrhapy.

An Experimental Study of the Effect of Vacuum Mixing on Fatigue Characteristics of Acrylic Bone Cement / 대한정형외과학회잡지

Contemporary cementing techniques improved the longevity of the cemented total hip replacement. The mechanical strength of acrylic bone cement can be changed by different handling techniques with reduction of the porosity of acrylic bone cement. The greatest improvement of the mechanical properties with reducing the porosity is that of the fatigue strength. We investigated the mechanical properties of the specimens of high viscosity, Palacos R(Merk, Darmstadt, FRG) bone cement with two mixing methods, hand and vacuum mixing. Vacuum mixing improved the ultimate tensile strength by 22.4% compared to hand mixing in previous study. For the uniaxial tension fatigue test, the specimens were cyclically loaded at a maximum stress of 25 MPa at a frequency of 2.5 Hz and to investigate the porosity, scanning electromicroscopic examination was taken in each hand mixed and vacuum mixed specimens. Scanning electromicrogram showed the vacuum mixed specimens to be the more uniform and free of small voids compared with the hand mixed specimens. The results of the fatigue test were analized using Weibull distribution of survival probability, the average number of cycles to failure was 1459±924 cycles in hand mixed specimens, in vacuum mixed specimens, 21491±14956 cycles. The average fatigue life of the vacuum mixed specimens was 15 times loanger than that of the hand mixed specimens by Weibull mean, this differene exists stastically within 95% confidence interval. We could suggest vacuum mixing technique as a method eliminating porosity in a chilled acrylic bone cement and thereby markedly improving the mechanical properties. In cemented joint replacement surgery, a vacuum mixing technique are recommended as a method of preparation of acrylic bone cement