Comparison of a New Braid Fixation System to an Interlocking Intramedullary Nail for Tibial Osteotomy Repair in an Ovine Model     

YAN LU  MD    BRETT NEMKE  BS    DOUGLAS M. LORANG  PhD    ROEL TRIP  MD    HIROHITO KOBAYASHI  MS    MARK D. MARKEL  DVM  PhD  Diplomate ACVS 《Veterinary surgery : VS》2009,38(4):467-476

Objectives— To compare bone healing of tibial osteotomy repaired with Nitinol wire braid and hardened steel rods (Braid system) and polymethylmethacrylate bone cement with an interlocking intramedullary (IM) nail fixation in an ovine model.
Study Design— In vitro and in vivo experimental study.
Animals— Adult female sheep (n=22).
Methods— Using sheep tibia, a middiaphyseal transverse osteotomy was performed in the right tibia, which were then randomly assigned to the Braid system group or IM nail group (n=5). The left tibia were used as controls. The torsional properties of tibial constructs were compared. The study was repeated in vivo in 12 sheep and mechanical properties and bone healing were evaluated at 12 weeks.
Results— In vitro, there was no significant difference in torsional stiffness between the groups. In vivo, operative time for the Braid system group was significantly shorter than the IM nail group. At 12 weeks, there were no significant differences in maximum torque and torsional stiffness between IM nail and Braid system groups nor were there significant radiographic or histologic differences between the groups.
Conclusions— The Braid system might decrease operative time for repair of transverse middiaphyseal tibial fractures and result in similar bone healing at 12 weeks after surgery compared with an interlocking IM nail repair.
Clinical Relevance— A Nitinol Braid system may be a treatment option for transverse midshaft tibial fractures.  相似文献   

Changes in the distribution of Atlantic cod (Gadus morhua) in the southern Gulf of St Lawrence — effects of environmental change or change in environmental preferences?     

DOUGLAS P. SWAIN 《Fisheries Oceanography》1999,8(1):1-17

Density-independent redistribution in response to changing temperature conditions and density-dependent redistribution in response to changing temperature preferences are two contrasting hypotheses to explain changes in the distribution of cod populations. I tested these hypotheses using survey data on the distribution of cod during the feeding season in the southern Gulf of St Lawrence. These tests used indices of cod distribution as the dependent variable and indices of cod abundance and bottom temperature as explanatory variables. Both hypotheses were often supported in univariate tests that ignored confounding between the two explanatory variables. Tests that accounted for this confounding indicated an effect of cod abundance on distribution for ages 4–8⁺ years, and 3⁺, but provided no support for an effect of environmental conditions on distribution except for age 3. Variation in the temperature distribution of cod was consistent with an effect of abundance on interannual variation in distribution and with no effect of environment except for age 3 cod. Age 3 cod were consistently under-represented in areas of very cold bottom water but older cod were not. As predicted by bioenergetic considerations, cod tended to occupy colder water at high levels of abundance, suggesting a mechanism for density-dependent shifts in distribution. Shifts in cod distribution during the feeding season in the southern Gulf appear to be more closely linked to density-dependent changes in environmental preferences than to density-independent responses to changing environmental conditions.  相似文献   

The effects of asulam, frond cutting and ground mineral phosphate on the yields of swards dominated by bracken [Pteridium aquilinum (L.) Kuhn]     

GARETH WILLIAMS  DOUGLAS FRASER 《Grass and Forage Science》1979,34(2):95-100

Two methods were adopted of measuring sward output, following the prevention of bracken frond growth, with differing results. Accumulated growth estimation, corresponding to production under a system of open-range grazing, showed that asulam used for frond control had no effect on herbage yield in the year of application and large increases were observed in succeeding years compared with untreated control plots. In measuring production by sward regrowth after cutting, corresponding to intensive pasture utilization systems, asulam reduced yields in the year of treatment and increases were not observed until 2 years later. The inhibition of growth could be overcome by applying ground mineral phosphate at rates of 300 or 500 kg ha^-1 before spraying but the 500 kg ha^-1 rate showed no advantage over 300 kg ha^-1. Applications of ground mineral phosphate after spraying had no effect on sward output. It is concluded that indigenous pasture plants in bracken-infested areas of western Scotland cease growth by mid July unless subjected to major earlier defoliation or severe soil moisture deficits and the removal of the frond canopy does not change this pattern significantly. Obtaining the full benefit of bracken clearance depends on making use of the resulting production of extra herbage and limiting as far as possible frond regrowth in treated areas.  相似文献