This study was to evaluate the effect of stress on the intervertebral disc and facet joint after implantation of device for intervertebral assisted motion (DIAM). Nine fresh human lumbar (L1-L5) cadavers were studied. The stress on L3-4, adjacent intervertebral disc and facet joints was measured in four groups. The cadavers in Group 1 were measured without special treatment; the lumbar discectomy and facet joint arthroplasty without implant were performed on L3-4 in Group 2. DIAM and ISOLA screw fixation in L3-4 interspinous was carried out in Group 3 and Group 4, respectively. The stress on disc intervertebrales and facet joint of L3-4 increased after lumbar diskectomy and facet joint arthroplasty. After DIAM fixation, the stress on L4-5, adjacent disc intervertebrales and facet joint was comparable to that under the normal condition. After ISOLA fixation, the stress on disc intervertebrales and facet joint of L3-4 decreased while that on adjacent disc intervertebrales increased. DIAM fixation can efficiently reduce the undesirable increase in stress due to lumbar diskectomy and facet joint arthroplasty and decrease the risk for the degeneration of adjacent disc intervertebrales caused by spinal fusion.