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COmparing Effects of Trabecular bone using Two nerve damage disuse models in mice: Sciatic nerve crush and sciatic neurectomy.  A. M. Miesse, J. R. Milstead, T. A. Bateman Department of Bioengineering, Clemson University, Clemson, SC. 

   This study compares two different nerve damage disuse osteoporosis models in female C57BL/6J mice: nerve crush (NC) and neurcetomy (NX) two weeks post surgery.  The primary difference between these two models is that the damage caused by NC is temporary, where the disuse caused by NX is permanent.  Sciatic nerve crush is used to study the secondary effects of peripheral nerve damage.  The sciatic neurcetomy doesn’t allow for recovery thus it can used for an analogous spinal cord injury model.  With an estimated 375,000 people suffering from spinal cord injuries and another 1.5 million afflicted by peripheral nerve damage in the United States the need for investigating ways of combating secondary effects, such as, bone loss is imperative. 
   The two groups of mice consisted of a nerve crush group (n=12) and neurcetomy group (n= 12).  The surgeries were done on the right hind limb of the mouse.  In the NC group the nerve was crushed between the sciatic notch and patella for 30 seconds using mosquito forceps.  In the NX surgeries, 3 mm of the sciatic nerve was removed from the same area as the nerve crush.  The left hind leg was not operated on and serves as a contralateral control.  Micro-computed tomography (Scanco Medical) was used to analyze proximal tibia trabecular bone 1 mm distal from the growth plate.  Micro-computed tomography is a method of imaging and quantifying the micro-architecture of bone at a resolution of 15 microns. 
   Comparing the right leg with the left leg netted significant statistical results.  The nerve crush group experienced a 37.4% (p<.001) decrease of trabecular bone volume BV and a 36.3% (p<.001) decline in trabecular density (BV/TV).  A 40.7% (p<.001) and 18.2% (p<.001) reduction in observed in NC connectivity density (Con. Dens.) and trabecular thickness (Tb.Th) respectively.  Similar trends were found in the NX group.  BV and BV/TV were diminished 32.6% (p<.001)and 31.8% (p<.001), respectively.  Con. Dens. (32.8%) (p<.001)and Tb.Th (15.6%) (p<.001) were also reduced by NX. 

(Supported by NASA / SC EPSCoR)