Association between the number of remaining teeth and pseudarthrosis after lumbar interbody fusion: A retrospective cohort study

Background: Pseudarthrosis is a major complication after posterior lumbar interbody fusion (PLIF) and transforaminal interbody fusion (TLIF), and its risk factors need to be identified. This study aimed to investigate the relationship between the number of remaining teeth (NRT) and pseudarthrosis.

Methods: NRT, preoperative bone density of the proximal femur (percentages of young adult mean; % YAM), and preoperative procollagen type 1 N-terminal propeptide (P1NP) (μg/L) were retrospectively investigated in 63 patients (24 male and 39 female, mean age: 71.2 years, mean follow-up: 49.1 months) who underwent single-level PLIF/TLIF (L3/4, L4/5, L5/S1). Fusion status was analyzed on computed tomography (CT) scan at 24 months after surgery.

Results: Pseudarthrosis was significantly more frequent in the NRT ≤10 group than in the NRT ≥11 group (p < 0.05). Compared with the fusion group, the pseudarthrosis group had significantly higher population of males and lower % YAM. Logistic regression analysis was performed with the following variable combination models; Model 1: age, % YAM, NRT; Model 2: P1NP, % YAM, NRT; Model 3: sex, % YAM, NRT. NRT ≤10 was associated with pseudoarthrosis in all models (model 1: 95 % confidence interval (CI): 1.81-25.14, odds ratios (ORs): 6.74, p < 0.01, model 2; 95 % CI: 1.57-30.54, ORs: 5.88, p = 0.01, model 3; 95 % CI: 1.95-39.02, ORs: 7.07, p < 0.01). Sex was associated with pseudarthrosis in model 3 (95 % CI: 1.23-16.92, ORs: 4.30, p = 0.02).

Conclusions: Small NRT was found to be a risk factor of pseudarthrosis after lumbar interbody fusion.