The phenomenon of progressive population aging has led to a rising prevalence of age-related degenerative spinal disorders in many countries [1–4]. Lumbar spinal stenosis (LSS) is the most common spinal degenerative disease, typically managed conservatively in its early stages. However, many patients eventually require surgical intervention due to the progression of pain and/or neurological symptoms [2,5]. Concurrently, the prevalence of osteoporosis in this population is likely to increase owing to age-related deterioration of the skeletal system. Indeed, a recent meta-analysis showed that osteoporosis is a frequent complication in patients with LSS [6].

In patients undergoing spinal fusion and corrective surgeries, decreased bone density is associated with postoperative complications such as adjacent vertebral fractures and implant failure [7,8]. Consequently, optimizing bone health during the perioperative period of spinal instrumentation surgery has been increasingly emphasized in recent years [9–11]. While previous studies have primarily examined the impact of osteoporosis on implant-related complications, its impact on surgical outcomes for LSS remains unclear. Therefore, this study aimed to investigate the impact of osteoporosis on LSS surgery during the perioperative period.

In this study, 10.6% of patients were diagnosed with osteoporosis. However, previous studies have reported higher prevalence rates of osteoporosis in LSS patients. A prospective cohort study found that 31.8% of LSS patients had osteoporosis based on bone densitometry [16]. Furthermore, a recent meta-analysis reported an even higher prevalence of osteoporosis (34.9%) in patients with LSS aged 50 or older [6]. Thus, the frequency of osteoporosis in LSS patients observed in this study was relatively low compared to prior literature. However, a recent study conducted in Japan found that among patients aged ≥65 years who underwent spinal fusion surgery between 2018 and 2021, 15.9% received osteoporosis medications preoperatively [17]. Therefore, the prevalence rate of osteoporosis in the present study is plausible, given the inclusion of patients across all age groups and the proportion of patients actively receiving treatment for osteoporosis. Thus, preoperative osteoporosis screening is crucial, given the low treatment rates for osteoporosis. A recent guideline for osteoporosis management in spine surgery recommends bone-anabolic agents as first-line treatment for patients with osteoporosis who are scheduled for multilevel spinal reconstruction. These medications should be administered for a minimum of 2 months preoperatively and continued for at least 8 months postoperatively [10].

Univariate and multivariate regression analyses revealed an association between osteoporosis and the occurrence of perioperative complications following surgery for LSS. While osteoporosis is a known risk factor for implant-related complications in lumbar fusion surgery [18,19], the impact of osteoporosis on systemic complications is not well characterized in contemporary literature. A previous retrospective study has identified osteoporosis as a risk factor for systemic complications after surgery for LSS [19]. However, the study did not account for the confounding influence of between-group differences regarding background factors. A retrospective study using the Mariner Claims Database identified osteoporosis as a risk factor for pulmonary embolism and minor complications following single-level posterior spine instrumentation and fusion and anterior lumbar interbody fusion [20]. Although the present study did not reveal a significant association between pulmonary embolism and osteoporosis, the higher incidence of complications in the osteoporosis group indicated a consistent trend.

Compared to the non-osteoporosis group, the osteoporosis group in this study was characterized by older age, a higher proportion of females, lower BMI, and a higher frequency of fusion surgery. To account for these confounding factors, PSM was employed. Even after matching, the osteoporosis group had a higher complication rate, consistent with the multivariate regression analysis. Furthermore, patients with osteoporosis incurred higher medical costs, required more blood transfusions, and had longer anesthesia times compared to those without osteoporosis. Large cohort studies have investigated the impact of osteoporosis on thoracolumbar spine surgery, examining outcomes such as medical costs, reoperations, and readmissions [21]. An 8-year follow-up study found that osteoporotic patients had higher readmission rates, longer hospital stays, and higher medical costs compared to non-osteoporotic patients [21]. In contrast, our study focused on the impact of osteoporosis on in-patient medical costs [21]. Collectively, these findings emphasize the importance of preoperative osteoporosis screening, as its presence in patients undergoing surgery for LSS likely increases the risk of complications and higher medical costs.

Our study suggests that the presence of osteoporosis is a risk factor for increased blood transfusion demand. Clinical evidence from various orthopedic surgeries supports this finding. For example, osteoporosis was identified as a risk factor for blood transfusion in total hip arthroplasty and total knee arthroplasty [22]. Furthermore, osteoporosis was found to be a risk factor for bleeding in femoral neck fractures [5]. Additionally, a retrospective study found that in patients with scoliotic spinal deformity, those with osteoporosis had a significantly higher risk of increased intraoperative blood loss [23]. Although the DPC database does not provide data on the amount of blood loss during surgery, the higher volume of blood transfusion in patients with osteoporosis suggests increased perioperative blood loss or lower tolerance for blood loss. This information can be valuable for preoperative patient counseling.

Some limitations of this study should be acknowledged. First, despite PSM, residual confounding variables such as nutritional status were not accounted for in the analysis, potentially influencing the observed outcomes. Second, retrospective analysis of large databases can be affected by coding errors, impacting data accuracy and interpretation. Nonetheless, using large sample sizes mitigates this risk. Third, the DPC database only codes patients receiving treatment, so patients classified as having osteoporosis were receiving some form of treatment for the condition. This may lead to undiagnosed or untreated osteoporosis cases in the non-osteoporosis group. Nonetheless, the study suggests that patients with osteoporosis have a high incidence of perioperative complications, even if they are receiving treatment for the condition. This indicates that the current treatment strategies for osteoporosis may not be sufficient to reduce perioperative complications. To address this, future research should investigate the causal relationship between osteoporosis and systemic complications of LSS surgery. This can be achieved by comparing three distinct groups: patients without osteoporosis, those with untreated osteoporosis, and those receiving pharmacological treatment for osteoporosis. Objective criteria, such as bone density measurements and imaging-based fracture assessment, should be used to classify these groups. Further studies should also investigate the optimal duration of osteoporosis treatment before and after spinal surgery, as well as the most effective medications. Prospective studies will also be necessary to elucidate the impact of osteoporosis on specific complications and outcomes in LSS surgery, ultimately informing evidence-based guidelines for perioperative management.

This large-scale retrospective analysis of a nationwide in-patient database revealed osteoporosis as an independent risk factor for perioperative complications in patients undergoing surgical treatment for LSS. The study found that patients with osteoporosis had significantly higher complication rates, greater medical costs, increased blood transfusion requirements, and longer anesthesia times compared to those without osteoporosis. These findings highlight the importance of preoperative osteoporosis screening and management in elderly patients to reduce the risk of perioperative complications.