Relationship Of Facet Tropism With Degeneration Of Disc And Facet Joint: An Imaging Study

BACKGROUND Lumbar facet tropism (FT) is common in patients with low backpain. However, for many years, the relationship of FT with intervertebral discdegeneration (DD) has been debated. And there are few studies about the relationshipof FT with facet joint degeneration (FJD) in patients with low back pain.OBJECTIVE To investigated the effect of FT on DD and FJD.DESIGN, TIME AND SETTING A classified control observation was performed atthe First Affiliated Hospital of Anhui Medical University from January2011to July2011.PARTICIPANTS312patients with low back pain or sciatica were included in thestudy. There were147male and165female. All patients have lumbar MRI.METHODS The differences of facet joint angle of936functional spinal units (312subjects) were measured. FT, which was defined as a difference of more than7°between the left and the right facet joints. The degree of DD and FJD wereclassified.MAIN OUTCOME MEASURES1. FT of936functional spinal units (312subjects)2. Degree of DD by Pfirrmann method 3. Degree of FJD by Fujiwara et al method.RESULTS1. There was no significant difference between male and female in facet orientation,FT degree and incidence of FT (P>0.05). There was no significant differencebetween male and female in incidence of facet joint osteoarthritis (OA) at L4/5andL5/S1, except at L3/4(P=0.03). There was no significant difference between groupsof “tilted to the left” and “tilted to the right” in all sample and the sample of FT(P>0.05).2. Facet orientation had a trend toward more sagittally with the increase of age at L3/4and L4/5(P=0.009), except at L5/S1(P>0.05).There was significant differenceamong age groups in FT degree (P=0.003) at L4/5.There was also significantdifference among age groups in incidence of FT at L4/L5(P=0.003), except at L3/4and L5/S1(P>0.05).3. There was no significant correlation between FT and DD.4. There was no significant correlation between DD and FJD.5. There was no significant difference between patients with or without OA in facetorientation（P>0.05）.There was significant difference between patients with orwithout OA in FT degree （P=0.002） and incidence of FT （P=0.003） at L4/5。But there was no significant difference at L3/4and L5/S1(P>0.05).6. At L4/5， facet orientation toward more sagittally in group of degenerativespondylolisthesis （DS）(P=0.037)。There was significant difference between DSand non DS in FT degree (P=0.042), but not in incidence of FT (P>0.05).CONCLUSION No significant correlation was observed between lumbar facettropism and disc degeneration. There was no significant correlation between DD andFJD. But at L4-L5, active sites of segmental motion, facet tropism may predispose to the development of FJD and DS.