Basic And Clinical Research On Low Back Pain Originating From Lumbar Facet Joint

Objective: To study the applied anatomy of the medial branch of the posteriorlumbar ramus, establish a rat model of lumbar facet joint osteoarthritis, generatean animal model for lumbar facet joint degeneration with hyperalgesia andresearch Hedgehog signaling pathway in degenerative lumbar facet jointsMethods:1、The medial branch of the posterior lumbar ramus and fibroosseouscanal were dissected in12cadavers. And measure the distance between the ridgeof transverse process roots and the position of posterior ramus divisions into alateral and medial branch, the distance of the medial branch in transverse processroot to the posterior median line and body surface, and the distance offibroosseous canal to posterior median line and body surface.2、CompleteFreund’s adjuvant (experimental group) and saline (control group) were injectedinto the right and left lumbar facet joint (L5-6) of60male SD rats randomly. Therats were euthanized and the lumbar spines were removed at3,7,14,21and28dayspost-operation. Interleukin-1β and tumor necrosis factor-α levels in the synoviumwere measured. Cartilage degeneration of lumbar facet joint was evaluated atmacroscopic level and histology obtained for toluidine blue staining and HEstaining by OARSI scores system.3、Eighty-eight male SD rats were randomlydivided into experimental group40, control group40, and blank group8. Theexperimental group were injected with5μL urinary plasminogen activator (uPA)into lumbar facet joint, control group with5μL saline, and the blank groupwithout injection. Preoperative and postoperative3,7,14,28,42,56days, the ratswere measured paw withdrawal threshold for mechanical hyperalgesia andthermal hyperalgesia, and catwalk ananlysis including print area, standphase,swing phase and swing speed.The rats were euthanized and the lumbar spines were removed at7,14,28,42,and56days post-surgery. Cartilagedegeneration of lumbar facet joint was evaluated according to OARSI scoressystem obtained for toluidine blue staining. The specimens were stained with HEand evaluated the inflammatory lesions of synovitis, and stainedimmunohistochemical IL-1β, TNF-α and iNOS.4、Twenty-four lumbar facetjoint samples of lumbar facet joint obtained from lumbar operation. Thedegeneration of lumbar facet joint was evaluated by MRI image according to theWeishaupt grading. The specimens of lumbar facet joint were stained withtoluidine blue, HE staining and immunohistochemical.The expression of theHedgehog target genes GLI1, PTCH1and HHIP were examined by RT-PCR.Those correlations were evaluated.Results:1、The distance between the ridge of transverse process roots and theposition of posterior ramus divisions into a lateral and medial branch is3.52~1.87mm. The distance of the medial branch in transverse process root to theposterior median line and body surface are2.4~3.3cm and3.1~4.6cm, respectively.The distance of fibroosseous canal to posterior median line and body surface are2.1~2.9cm and2.2~4.0cm, respectively.2、The macroscopic scores and OARSIscores of experimental group were higher than control group (P＜0.05). Theconcentration of tumor necrosis factor-αwas significantly increased only on Days3and7when compared with controls, and interleukin-1β was on Days3,7and14（P <0.05）.3、The differences were statistically significant between experimentalgroup and control group or blank group in mechanical hyperalgesia and print areaafter operation3days,7days and14days (P＜0.05). The differences werestatistically significant between experimental group and control group or blankgroup in thermal hyperalgesia, stand phase,swing phase and swing speed, afteroperation3days,7days,14days and28days (P＜0.05). The differences werestatistically significant between experimental group and control group in cartilagedegeneration stained with toluidine blue according to OARSI scores system atafter operation7days,14days,28days,42days and56days (P＜0.01). The differences were statistically significant between experimental group and controlgroup in synovial inflammatory score after operation7days,14days,28days,42days and56days (P＜0.01). The differences were statistically significant betweenexperimental group and control group in the expression of IL-1β, TNF-α andiNOS, after operation7days,14days,28days,42days and56days (P＜0.01).4、The OARSI score and Weishaupt grading are positively correlated (P <0.01). TheOARSI score and Weishaupt grading are positively correlated with the expressionof GLI1, PTCH1and HHIP (P <0.01).Conclusion:1、The nerve of lumbar facet joint mainly originates from medialbranch of posterior ramus.2、The rat model is established by intra-articluarinjection of adjuvant can induce degeneration of the lumbar facet joint. It can beuseful for studies on lumbar facet joint osteoarthritis.3、The rat model isestablished by intra-articluar injection of uPA can be useful for studies on pain oflumbar facet joint degeneration.4、Hedgehog signaling regulates degeneration ofthe lumbar facet joint.