Publication: Lumbar facet joint angle among malaysians: its predictive value in prolapsed intervertebral disc and determining feasibility of lumbar microendoscopic discectomy without violation of facet joint. Masters thesis, Universiti Sains Malaysia.
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Date
2013
Authors
Azman, Nur Azhar @ Azzahra Nurul
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Abstract
Microendoscopic discectomy (MED), a minimally invasive spine surgery for lumbar disc herniation which relies very much on line-of-sight visualization needing laminectomy as well as removal of the medial part of facet to enlarge the interlaminar window to secure an adequate working space. Violation of the facets or objectively defined as removal (facetectomy) more than half of the medial/superior part of the facet are more common in patients with facet angles less than 35 degrees (from sagittal plane). Among Americans, when both facet joints were sagittally oriented (taken as>45 degrees from coronal/horizontal plane), there was a significant association as well as higher risk for disc herniation whereas Turkish patients showed asymmetry and sagittalization of facet joint. This means that there is a high chance that surgeon will have a narrow surgical corridor and facetectomy is unavoidable particularly in patients with facet angles less than 35 degrees. This study, intended to demonstrate the significant association between sagittal orientation of facet joint with disc herniation, therefore helps in predicting the incidence of prolapsed intervertebral disc based on the fact that sagittalization of facet joint proceeds dies prolapse. This study also described the variation in lumbar facet joint angle among PID patient in HUSM therefore helps in determining feasibility of Lumbar Microendoscopic discectomy without violation of facet joint. The aim is to avoid complications of facet resection which include increased postoperative pain, secondary painful degenerative spondylosis and theoretically, possible vertebral segment instability over time. This so-called minimally invasive procedure could potentially be more destructive to the articulating facet than the classic open discectomy. Knowing the facet integrity before surgery may allow the surgeon to better plan the operation or choose classic open discectomy instead. This was a case control study from March 2011 until November 2012 for a total of 21 months. MRI lumbosacral of 41 patients with low back pain done in Radiology Department, at Hospital Universiti Sains Malaysia (HUSM) using MRI machine 1 0T Signa Horizon LX was analysed while source of population for control group were 17 volunteers from HUSM Radiology Department staffs who fulfilled the similar inclusion and exclusion criteria as PID group. Ethical clearance was obtained from Research Ethics Committee (Human), Universiti Sains Malaysia. All lumbar intervertebral discs were analyzed for presence of disc herniation or bulge. Measurement of facet joint angle relative to the sagittal plane was done on both sides at the level L4-L5, L5-S1 with Picture Archiving Communication System (PACS). Data entry and analysis were performed using Statistical Package for Social Sciences PASW (R) Statistics 18. There was a significant association between gender and PID with men had an 5.63 times more likely to have PID at level ofL5-Sl (95% CI 1.32,24.06, p< 0.050). There was a significant association between age and PID with an increase in 1 year of age had a 1.1 time greater risk [(95% CI 1.01,1.14, p <0.050) for L4-L5 and (95% CI 1.01,1.16, p <0.050) forL5-Sl], Weight was a significant risk factor in PID with the mean weight in PID patients higher (68.95) than non-PID individuals (55.35), p=0.06. There was a significant negative correlation between body weight and the degree of facet joint angle for right L4-L5 facet angle (r = -0.28, p =0.034 ). Unilateral sagittal orientation of facet joint (on either side) or facet tropism had a 5.22 times (at level of L4-L5) and 11.39 times (at the level of L5-S1) greater risk to develop PID. (95% CI 1.24,22.07, p <0.050); (95% CI 1.09,118.74, p <0.050), respectively). Majority of the unilateral sagitally-oriented facet joint in PID patients fell in the group of angle between 35 to 44 degrees. At level of L4-L5, right and left side singly had only 20% and 12% of less than 35 degrees angle, respectively. L5-S1 contributed to a lesser amount, which was 10% and 2% in this group. Male gender and increasing age showed increasing risk for PID (just for L5-S1). Increasing body weight was also a significant risk factor for PID with mean body weight of PID patients was more than non-PID individuals. Increase in weight correlated with reduction in the right L4-L5 facet joint angle from sagittal plane. Unilateral sagittal orientation of facet joint (on either side) or facet tropism also revealed greater risk for PID. Majority of the unilateral sagitally-oriented facet joint in PID patients fell in the group of angle between 35 to 44 degrees, therefore Malaysians were generally, suitable candidate for MED without violating the facet joint.