<Introduction> Poor bone quality is closely related to instrumentation failure and pseudarthrosis in lumbar interbody fusion. Preoperative intervention is strongly recommended for the patients with “osteoporosis”, but it remains unclear how to manage “osteopenia” for pre- and post-operative periods. The purpose of this study was to investigate the incidence of instrumentation-related complications and fusion status after lumbar interbody fusion in the patients with “osteopenia” versus normal bone health.
<Methods> A single center retrospective analysis was conducted in patients who had undergone posterior/transforaminal lumbar interbody fusion (PLIF/TLIF) for degenerative lumbar disease from January 2017 to December 2022 with a minimum 12-month radiographic follow-up. A total of 628 consecutive anti-osteoporotic treatment-naive patients (330 [52.5%] male and 298 [47.5%] female; mean age [SD], 67.9[11.0] years; age range, 25-90 years) who were examined by Dual-energy X-ray Absorptiometry (DEXA) scan within six months before surgery were reviewed. Based on the lowest T-score of femoral neck or total lumbar spine, 342 patients (222 [64.9%] males and 120 [35.1%] females) had normal bone quality (Group N : T-score≧-1.0), 260 patients (104 [40.0%] males and 156 [60.0%] females) had osteopenia (Group P:-1.0＞T-score＞-2.5), and 26 patients (4 [15.4%] males and 22 [84.6%] females) had osteoporosis (-2.5≧T-score). The incidence of intraoperative endplate violation, cage retropulsion, cage subsidence (>2mm), screw loosening, pseudoarthrosis, vertebral fracture and revision surgery at one-year after surgery were compared using Fisher’s exact test between Group N and Group P.
<Results> Osteopenia was diagnosed in 41.4% of all patients, 31.5% of males and 52.3% of females. Mean age was higher in Group P (70.0 vs 66.0: p<0.01). The incidence of intraoperative endplate violation (6.9% vs 2.9%: p=0.03), cage subsidence (21.2% vs 11.9%: p<0.01) and vertebral fracture (3.5% vs 0%: p<0.01) were significantly higher in Group P. However, there were no statistically significant differences between Group P and Group N in the incidence of cage retropulsion (2.7% vs 3.8%), screw loosening (24.6% vs 24.3%), pseudoarthrosis (12.8% vs 10.1%), and revision surgery (1.9% vs 3.2%).
<Discussion> More than 40 percent of patients who had undergone elective lumbar fusion surgery had osteopenia. When compared with normal bone health, osteopenia was significantly related to endplate violation, cage subsidence and vertebral fracture after PLIF/TLIF. Our results suggest that anti-osteoporotic treatment prior to lumbar fusion surgery might be valuable for patients with not only “osteoporosis” but “osteopenia” to prevent instrumentation-related complications.