RESUMEN
Objective To investigate the relationship among the spinous process open degree,the relative displacement of the lumbar facet joints(LFJ),and the morphologic change of the intervertebral foramina.Methods From Nov 2010 to Jun 2012,a total of 6 human fresh cadaveric spines was used in this study.All the ligaments were kept.The relative displacement of the corresponding segments LFJ,and the change of height and width of intervertebral foramen were measured through the corresponding open L3-4 and L4-5 spinous process,respectively.Results Lumbar degeneration was described with the following indices including the proliferation and displacement of LFJ,deformation of the intervertebral foramen morphogenesis,nerve root oppression,and lumbar intervertebral stenosis.When the interspinous process spacer was opened up to 2 mm,lumbar intervertebral foramen heights at the L3-4 and L4-5 [(15.62 ± 0.73) mm,(14.67 ± 0.75) mm] were significantly increased (t =26.00,16.02,P ＜ 0.01) compared to the original state [(13.89 ± 0.77) mm,(12.48 ± 0.80)mm].When the interspinous process spacer was opened up to 4mm,lumbar intervertebral foramen heights at the L3-4 and L4-5 [(17.13 ± 0.78) mm,(16.74 ± 0.76) mm] were significantly increased (t =36.15,30.69,P ＜ 0.01) compared to the original state.The foraminal height with a 4 mm distraction was significantly greater than the 2 mm distraction (t =20.82,21.72,P ＜0.01).When the interspinous distraction was 2 mm,L FJ displacement at the L3-4and L4-5 [(0.31 ±0.04) mm,(0.34 ± 0.07) mm] was significantly better than the original state [(0.63 ± 0.03) mm,(0.56±0.05)mm] (t =61.97,58.91,P ＜0.01).When the interspinous distraction was 4 mm,LFJ displacement at the L3-4 and L4-5 [(0.10 ±0.04) mm,(0.12 ±0.06) mm] was significantly better than the original state (t =18.69,18.88,P ＜0.01).No significant difference was found in the change of the intervertebral foramen width [(8.65 ± 0.38) mm,(7.78 ± 0.37) mm] at the 2 mm interspinous distraction compared to the original state(P ＞ 0.05),but a statistically significant difference was found at the 4 mm interspinous distraction compared to the original state [(9.03 ± 0.41) mm,(8.05 ± 0.32) mm] (t =7.78,7.97,P ＜ 0.01).Conclusions Spinous process shove off can effectively improve LFJ displacement,and increase the intervertebral foramen height,but the increase of its width needs to shove off enough distance.