Narrow Results

Up to now there have been two contradictory opinions in regard to lumbar facet role in the development of disc degeneration and herniation. To reconfirm the clinical validity of facet arrangement in the development of early disc degeneration and herniation, this study was carried out. For this purpose, the relationship between lumbar unilateral disc protrusion and geometry of the facet joints in the transverse plane was investigated. Method: The facet geometry was measured at the L₄ disc level in the 35 protruded disc patients and L₅ disc level in the 19 protruded disc patients. The computed tomographic scan sections were made 2mm intervals. The discs of L₄ and L₅ levels in the patients without disc protrusion and patients with spine injury were used as control. Results: 1. The facet angle showed the different individual variance. Among the L${}_{4-5}$ disc herniation group, the mean facet angle in the protruded and opposite sides and control were $49\pm 8.8^{\circ }$ (29–70${}^{\circ }$), $48\pm 8^{\circ }$ (29–65${}^{\circ }$), and $48\pm 8^{\circ }$ (30–65${}^{\circ }$). Those values at L₅-S₁ level were $53\pm 11^{\circ }$ (35–79${}^{\circ }$), $51\pm 7^{\circ }$ (36–79${}^{\circ }$), and $52\pm 10^{\circ }$ (36–79${}^{\circ }$), respectively. 2. Transverse interfacet angle (TIFA) of the L${}_{\mathrm{\text{4-5}}}$ protruded disc level and that of control were 97–14${}^{\circ }$ (59–125${}^{\circ }$) and $96\pm 16^{\circ }$ (66–127${}^{\circ }$). Those of L₅-S₁ level were $104\pm 19^{\circ }$ (70–132${}^{\circ }$) and $104\pm 19^{\circ }$ (76–151${}^{\circ }$). 3. The angle difference between both sides in the case of the facet asymmetry at L${}_{4-5}$ disc level was $6.51\pm 5.91^{\circ }$ (0–30${}^{\circ }$), and that of the control was $4.95\pm 3.88^{\circ }$ (0–15${}^{\circ }$), and those of L₅-S₁ level were $8\pm 6.41^{\circ }$ (0–24${}^{\circ }$) and $6.18\pm 6.64^{\circ }$ (0–24${}^{\circ }$), respectively. Disc herniation developed toward the more obliquely aligned facet joint side in 19 (54.2%) out of the 35 patients at the L${}_{4-5}$ disc, while disc herniation at L₅-S₁ level developed toward the more obliquely aligned facet joint side in 11 (57.9%) out of the 19 patients. 4. Among the L${}_{4-5}$ disc level, the mean moment arm angles in the disc-protruded side, the opposite side and control were $22\pm 4^{\circ }$ (16–40${}^{\circ }$), $22\pm 4^{\circ }$ (15–35${}^{\circ }$), and $22.4\pm 4^{\circ }$ (16–35${}^{\circ }$). Those of L₅-S₁ level each were $26\pm 4^{\circ }$ (21–36${}^{\circ }$), $25\pm 5^{\circ }$ (17–35${}^{\circ }$), and $28\pm 4^{\circ }$ (16–35${}^{\circ }$), respectively. 5. At the L${}_{4-5}$ level, the mean non-dimensional facet depths in the disc-protruded side, the opposite side, and control were $0.14\pm 0.08^{\circ }$ (0–0.36${}^{\circ }$), $0.15\pm 0.08^{\circ }$ (0–0.41${}^{\circ }$), and $0.18\pm 0.06^{\circ }$ (0.02–0.28${}^{\circ }$). Those facet depths at L₅-S₁ level were $0.12\pm 0.07^{\circ }$ (0.02–0.28${}^{\circ }$), $0.09\pm 0.04^{\circ }$ (0.02–0.2${}^{\circ }$), and $0.11\pm 0.05^{\circ }$ (0.02–0.28${}^{\circ }$). Conclusion: The five parameters including facet angle showed clinically no significant correlation with the disc herniation.