Sacroiliac Joint Degeneration After Lumbar or Lumbosacral Fusion Surgery-A Comparative Study of the Number of Fused Segments and Sacral Fusion.

ABSTRACT

OBJECTIVE: In this study, we aimed to investigate whether multi-segment fusion or fusion-to-sacrum increases sacroiliac joint (SIJ) pathology compared with single-segment fusion or a non-fused sacrum. METHODS: This study included 116 patients who underwent lumbar or lumbosacral fusion and were followed up for 2 years. The patients were classified into single-segment fusion (n = 46) and multi-segment fusion (more than two levels, n = 70) groups and then reclassified into the non-fused sacrum (n = 68) and fusion-to-sacrum groups (n = 48). Preoperative and postoperative radiographs were used to evaluate radiographic parameters, and computed tomography (CT) was used to evaluate SIJ degeneration. Low back pain (LBP) was assessed using a visual analog scale (VAS, 0-10). Baseline and postoperative values were compared using a paired sample t-test. RESULTS: LBP VAS scores significantly differed at 6 months (single-segment fusion, 3.04±1.88; multi-segment fusion, 4.83±2.33; P < 0.001) and 2 years postoperatively (single-segment fusion, 3.3±2.2; multi-segment fusion, 4.78±2.59; P = 0.094). There was no significant difference in SIJ degeneration, as assessed by CT scan, between the 2 surgical groups 14 (30%) and 19 (27%) patients in the single-segment and multi-segment (P = 0.701) fusion groups, respectively. The LBP VAS scale showed comparable differences at 1 (non-fused sacrum, 3±2.18; fusion-to-sacrum, 3.74±2.28; P = 0.090) and 2 years postoperatively (non-fused sacrum, 3.29±2.01; fusion-to-sacrum, 4.66±2.71; P = 0.095). CT scan revealed that 18 (26%) and 15 (31%) patients in the non-fused sacrum and fusion-to-sacrum groups, respectively, developed SIJ arthritis; however, there was no significant intergroup difference (P = 0.574). CONCLUSIONS: SIJ degeneration occurs independent of the number of fused segments or sacrum involvement.