The study of adjacent segmental facet joint degeneration following single or double-level lumbarspinal fusion

English Keywords:Lumbar fusion  Adjacent segment degeneration  Facet joint

English Abstract:

  【Abstract】 Objectives: To analyze the effect of single or double-level lumbar spinal fusion on the degeneration of the facet joint(FJ) in the adjacent segments, and to discuss the risk factors of the adjacent FJ degeneration. Methods: A retrospective analysis was performed on 49 patients with degenerative lumbar spinal disease undergoing PLIF in our hospital from January 2009 to December 2015, including 27 males and 22 females, with an average age of 55.4±8.6 (41-72) years and follow-up of 33.0±6.6(20-42) months. According to the number of fusion segments, 26 patients were classified into the L4/5 group and 23 patients into the L4-S1 group. Patients′ gender, age, follow-up time, history of smoking, history of hypertension, diabetes, body mass index(BMI), and other general data were collected. Then the incidence of adjacent segment degeneration of intervertebral disc height, facet joint angle asymmetry degree using X-ray, CT and MRI imaging characteristics at preoperation and at final follow-up were compared. The FJ degeneration was assessed according to Weishaupt classification, and the degree of FJ degeneration was compared between two groups by rank sum test. Results: There was no statistical difference in general data such as sex, age, follow-up time, smoking history, hypertension, diabetes or BMI(P>0.05). The rates of joint space stenosis and subchondral bone erosion were 51.9% and 38.4% in L4/5 group before operation, 73.1% and 67.3% respectively at final follow-up. The incidence rates of joint space stenosis and subchondral bone erosion of L4-S1 group were 67.3% and 34.8% preoperatively, and 97.8% and 60.9% at the final follow-up. At the final follow-up, the rate of moderate and severe degeneration in adjacent FJ was 52% in L4/5 group and 78.2% in L4-S1 group, repectively. Before operation, the height of intervertebral space and the degree of asymmetry of facet angle in L4/5 group were 8.95±0.38mm and 7.79°±0.21°; while those in L4-S1 group were 8.65±0.63mm and 7.90°±0.09° respectively. At final follow-up, L4/5 group was 8.33±0.51mm and 10.43°±0.33°, L4-S1 group was 7.68±0.53mm and 12.06°±0.20°(P＜0.05). Conclusions: The multi-level posterior segment fusion fixation is more likely to cause FJ degeneration in the adjacent segment than the single segment fusion. And it is more likely to cause asymmetry of the articular process.