Prevalent morphometric vertebral fractures as a risk factor for subsequent clinical vertebral fractures after shortfusion surgery in older Japanese women with degenerative spondylolisthesis.

STUDY DESIGN: A retrospective cohort study using the Kaplan-Meier method with propensity-score matching. PURPOSE: To evaluate whether the presence of prevalent morphometric vertebral fractures (VFs) poses a risk for subsequent clinical VFs after short-fusion surgery in women aged ≥60 years with degenerative spondylolisthesis. OVERVIEW OF LITERATURE: VFs are common osteoporotic fractures and are associated with a low quality of life. Subsequent VFs are a complication of instrumented fusion in patients with degenerative lumbar disorders. Thus, risk factors for subsequent VFs after fusion surgery must be analyzed. Population-based studies have suggested that prevalent morphometric VFs led to a higher incidence of subsequent VFs in postmenopausal women; however, no studies have investigated whether prevalent morphometric VFs are a risk factor for subsequent VFs after fusion surgery in patients with degenerative spondylolisthesis. METHODS: The study enrolled a total of 237 older female patients: 50 and 187 patients had prevalent morphometric VFs (VF [+] group) and nonprevalent morphometric VFs (VF [-] group), respectively. The time to subsequent clinical VFs after fusion surgery was compared between the two groups using the Kaplan-Meier method. Moreover, 40 and 80 patients in the VF (+) and VF (-) groups, respectively, were analyzed and matched by propensity scores for age, follow-up duration, surgical procedure, number of fused segments, body mass index, and number of patients treated for osteoporosis. RESULTS: Kaplan-Meier analysis indicated that the VF (+) group had a higher incidence of subsequent clinical VFs than the VF (-) group, and Cox regression analysis showed that the presence of prevalent morphometric VFs was an independent risk factor for subsequent clinical VFs before matching. Kaplan-Meier analysis demonstrated comparable results after matching. CONCLUSIONS: The presence of prevalent morphometric VFs may be a risk factor for subsequent clinical VFs in older women with degenerative spondylolisthesis who underwent short-fusion surgery.

Association between ligamentous stenosis at spondylolisthetic segments before fusion surgery and symptomatic adjacent canal stenosis at follow-up in patients with degenerative spondylolisthesis.

STUDY DESIGN: A retrospective case-control propensity score-matching study. PURPOSE: This study aimed to longitudinally evaluate whether preoperative ligamentous stenosis at the spondylolisthetic segments could affect the incidence of symptomatic adjacent canal stenosis following one-segment fusion surgery. OVERVIEW OF LITERATURE: Several risk factors for symptomatic adjacent canal stenosis following fusion surgery have been assessed. Patients with lumbar canal stenosis mainly due to ligamentum flavum (LF) hypertrophy (ligamentous stenosis) also have LF hypertrophy in other segments. METHODS: In total, 76 patients participated in this case-control study (neurologically symptomatic adjacent canal stenosis, n=33; neurologically asymptomatic cases at follow-up, n=43). Their risk factors during surgery and magnetic resonance (MR) images before the surgery and at follow-up were evaluated. Data from the two groups (n=25 each) were matched using propensity scores for age, sex, time to MR imaging at follow-up, surgical procedure, and LF hypertrophy in adjacent segments before the surgery and analyzed. RESULTS: Compared with the asymptomatic group, the symptomatic adjacent canal stenosis group had a significantly larger LF area/spinal canal area in the spondylolisthetic segments before the surgery. During the follow-up periods (in months), they had a larger LF area/ spinal canal area in the adjacent segments: the two values were significantly correlated. The sensitivity, specificity, and positive and negative predictive values for determining symptomatic adjacent canal stenosis were high compared with on the cutoff value for the LF area/spinal canal area at the spondylolisthetic segments before the surgery. These results were the same after matching. CONCLUSIONS: Symptomatic adjacent canal stenosis is mainly caused by LF hypertrophy. Ligamentous stenosis at the spondylolisthetic segments before fusion surgery might be strongly associated with symptomatic adjacent canal stenosis at follow-up.