Abstract
Introduction
Osteoporotic vertebral fractures (OVFs) are a significant problem among older patients who are undergoing spine surgery. This study examined the influence of incident OVFs on clinical outcomes and spinal alignment 5 years following short-segment fusion (SSF) for lumbar spinal stenosis.
Methods
We studied 88 patients who underwent SSF (≤2-disc level) for lumbar spinal stenosis with instability and were followed up for more than 5 years postoperatively. Those with prior OVFs were excluded. We evaluated incident OVFs with plain whole-spine lateral radiography preoperatively (before) and at 5 years postoperatively (after). Using preoperative lumbar computed tomography, Hounsfield unit (HU) values were evaluated. The patients were classified into two groups according to the presence of incident OVFs. Repeated-measures analysis of variance was utilized to compare the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and the 36-item Short-Form Health Survey (SF-36), and spinal parameters were recorded before and after. Multiple linear regression analyses were employed to investigate the association between the incident OVFs and the clinical scores and spinal alignment recorded after.
Results
In the fracture group, the clinical course of low back pain score on the JOABPEQ, physical component summary SF-36 score, and spinal alignment including C7 sagittal vertical axis (SVA), thoracic kyphosis (TK), and pelvic tilt were significantly worse. Multiple linear regression revealed a significant correlation between incident OVFs and worse 5-year postoperative spinal alignment, which includes SVA and TK. The optimal threshold for the HU values for predicting the incidence of OVFs within 5 years postoperatively was 83.0 (area under the curve 0.701).
Conclusions
Incident OVFs in patients following SSF were significantly correlated with the 5-year clinical outcomes and spinal alignment. Patients at risk of OVFs, especially those with HU values below 83, must take preventive measures against OVFs, as this could prevent deteriorating midterm postoperative clinical outcomes and spinal alignment.
Level of Evidence
3
Keywords: vertebral fractures, lumbar fusion surgery, patient-reported outcomes, lumbar spinal stenosis, osteoporosis, quality of life
Introduction
As the global population of older patients increased, the number of elective lumbar fusion procedures in this population has also increased1). Fusion application in patients with lumbar spinal stenosis has been previously reported2,3), and the clinical outcomes of fusion surgery must be improved. Given the complexity of spinal surgery, the performance of fusion surgery is impacted by various factors. A recent review article has highlighted the significance of managing osteoporosis to improve spinal surgery outcomes4). Accordingly, osteoporotic vertebral fractures (OVFs) have become a major issue among the older population undergoing lumbar fusion surgery5). Moreover, spinal instrumentation alters the normal biomechanics of the spine, which often leads to lesions in segments adjacent to the fused section6,7). Therefore, the occurrence of adjacent vertebral fracture (AVF) should also be taken into account for successful lumbar fusion surgery.
The attainment of global sagittal alignment is also pivotal for successful lumbar fusion surgery. Recent studies have revealed that sagittal spinal imbalance and spinopelvic malalignment have a significant effect on the surgical outcomes after short-segment lumbar fusion surgery8,9). The poor global sagittal imbalance may arise because of subsequent disc degeneration at the unfused segment or adjacent segment disease10), although the influence of OVFs on poor global alignment has not yet been reported.
To date, no studies have investigated the impact of incident OVFs on midterm clinical outcomes and spinal alignment following lumbar fusion surgery. Therefore, in this study, we examined the influence of incident OVFs on clinical outcomes and spinal alignment 5 years after short-segment fusion (SSF) for lumbar spinal stenosis.
Materials and Methods
Ethical statements
This was a retrospective, cohort study. The institutional review board of our institution approved the study protocol. This study received no funding.
Patient population
A total of 147 patients underwent SSF (≤2-disc level) for lumbar spinal stenosis with instability at our institution between 2009 and 2016. Patients were excluded if they had previous OVFs and could not complete patient-oriented questionnaires at 1, 2, and 5 years, postoperatively. This study included 88 patients (60 women), and the follow-up rate was determined to be 59.8%. The average age of the patients was 69.3±8.4 years at surgery. The average number of fusion segments was 1.3±0.5. The average follow-up period was 8.0±2.3 years.
Surgical indication for SSF
Segmental instability was assessed preoperatively in all patients using a plain lateral radiograph of the lumbar spine. Our institution defined segmental instability as follows: >5° segmental kyphotic angle and >10° change in segmental intervertebral angle and a 3 mm slip increase at the surgical level during flexion. We performed SSF in patients with lumbar spinal stenosis and instability, and the levels of stenosis were related to the symptoms. Posterior lumbar interbody fusion or unilateral transforaminal lumbar interbody fusion was carried out as an SSF. All fusion areas were from L1 to S1.
Patient demographic data
Patient demographic data, which include age, sex, body mass index (BMI), use of medication for osteoporosis, use of glucocorticoids, comorbidities (diabetes mellitus and rheumatoid arthritis), surgical complications, and the level of fusions, were extracted from the medical records.
Radiographic evaluation
The following radiographic parameters were evaluated using standing posterior-anterior and lateral radiographs preoperatively, at 2 and 5 years, postoperatively: (1) the C7 sagittal vertical axis (SVA), (2) the degree of thoracic kyphosis (TK; T5-12), (3) the degree of lumbar lordosis (LL; T12-S1), (4) pelvic tilt (PT), and (5) pelvic incidence (PI).
We assessed incident vertebral fractures with plain lateral radiography of the whole-spine preoperatively and at 5 years postoperatively. The degree of vertebral fracture was graded into four categories concerning vertebral height loss based on the Genant classification11): grade 0, normal; grade 1, mild fracture, <25% loss of height; grade 2, moderate fracture, 25%-40% loss of height; and grade 3, severe fracture, >40% loss of height. A Genant grade of ≥2 was considered a vertebral fracture. Moreover, a vertebral fracture that occurs immediately above or below the site of instrumented spinal fusion was categorized as an AVF. The Hounsfield unit (HU) value was evaluated by placing an elliptical region of interest on the axial images at L1-L4 in the middle of the vertebral body. The HU value was evaluated using the average value obtained from each level. According to Joseph et al., the largest possible elliptical region of interest was drawn for each measurement, which excludes the cortical margins to prevent volume averaging12). Using Synapse 3D viewer software OB-V (Fuji Film Co, Japan), all radiographic parameters were measured.
Clinical evaluation
The score of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) was recorded preoperatively and at 1, 2, and 5 years postoperatively. For the patient-oriented questionnaires, the 36-item Short-Form Health Survey (SF-36) for evaluating health-related quality of life (HRQOL) was evaluated. Subscale scores were summarized as physical component summary (PCS) and mental component summary (MCS) according to the formula proposed in a previous report13). All the clinical scores were recorded preoperatively and at 1, 2, and 5 years postoperatively.
Statistical analysis
The patients were categorized into two groups based on the presence of incident OVFs. Using Fisher's exact test for categorical variables and the Mann-Whitney U test for continuous variables in the univariate analysis, demographic data and radiographic parameters were compared between the two groups. Repeated-measures analysis of variance was used to compare clinical scores of the JOABPEQ and SF-36 recorded preoperatively and at 1, 2, and 5 years postoperatively, as well as spinal parameters recorded preoperatively and at 2 and 5 years postoperatively. Multiple linear regression analyses were used to examine the association between the incident OVFs and AVF, and the clinical scores recorded 5 years postoperatively, considering the JOABPEQ scores and PCS and MCS scores of SF-36 as objective variables. The incident OVFs, AVF, age, sex, BMI, and each preoperative score were included as explanatory variables. Likewise, the association between spinal parameters recorded 5 years postoperatively and vertebral fractures were analyzed, with the incident OVFs, AVF, age, sex, and BMI considered as explanatory variables. Moreover, to determine the cutoff values of the HU value for the incidence of OVFs within 5 years postoperatively, the receiver operating characteristic curve analysis was carried out. All analyses were carried out using R (version 3.5.1, patched; The R Foundation, Vienna, Austria). Statistical significance was set at P<0.05.
Results
Prevalence of vertebral fracture
A total of 33 vertebral fractures were observed in this study. Of the vertebral fractures, 23 (69.6%) and 10 (30.4%) were classified as grades 2 and 3, respectively, based on the Genant classification. Eleven patients (12.5%) had one vertebral fracture, five (5.6%) had two vertebral fractures, and four (4.5%) had three vertebral fractures. AVF occurred in four patients (4.5%), at L2 (two patients) and at L3 (two patients). Fig. 1 illustrates the characteristics of the incident vertebral fractures.
Figure 1.
Distributions of the levels of incident OVFs graded according to the Genant classification. OVF, osteoporotic vertebral fractures
Preoperative status
Table 1 presents the demographic data of the two groups classified according to the presence of incident OVFs. The fracture group had a significantly higher female rate (90.0% vs. 61.8%, P=0.027), lower HU values (90.2 vs. 118.3, P=0.014), and lower PCS score of the SF-36 (9.3 vs. 18.4, P=0.013) when compared with the nonfracture group. In other demographic factors including fusion levels, surgical complications, and preoperative scores between the two groups, no significant differences were found.
Table 1.
Demographics of the Nonfracture and Fracture Groups.
| Nonfracture (n=68) | Fracture (n=20) | P value | |
|---|---|---|---|
| Average age (years) | 68.9±9.1 | 70.8±5.6 | 0.370 |
| Sex (female) | 42 (61.8%) | 18 (90.0%) | 0.027* |
| BMI (kg/m2) | 23.6±3.0 | 23.3±4.5 | 0.774 |
| Use of medication for osteoporosis | 17 (25.0%) | 9 (45.0%) | 0.100 |
| Use of glucocorticoid | 4 (5.9%) | 2 (10.0%) | 0.615 |
| Comorbidity | |||
| Diabetes | 12 (17.6%) | 3 (15.0%) | 1.000 |
| RA | 3 (4.4%) | 1 (5.0%) | 1.000 |
| Hounsfield units | 118.3±45.1 | 90.2±38.8 | 0.014 |
| Fusion levels | 0.866 | ||
| One level | |||
| L2/3 | 6 (8.8%) | 0 (0%) | |
| L3/4 | 4 (5.9%) | 2 (10.0%) | |
| L4/5 | 33 (48.5%) | 11 (55.0%) | |
| L5/S | 8 (11.8%) | 2 (10.0%) | |
| Two levels | |||
| L2/3/4 | 2 (2.9%) | 0 (0.0%) | |
| L3/4/5 | 10 (14.7%) | 4 (20.0%) | |
| L4/5/S | 5 (7.4%) | 1 (5.0%) | |
| Surgical complication | |||
| Refusion surgery | 2 (2.9%) | 1 (5.0%) | 0.543 |
| Surgical site infection | 1 (1.5%) | 0 (0%) | 1.000 |
| Preoperative clinical score | |||
| JOABPEQ | |||
| Lumbar function | 35.1±27.9 | 48.5±32.2 | 0.072 |
| Low back pain | 57.7±30.2 | 43.2±30.5 | 0.064 |
| Walking ability | 23.6±21.4 | 19.6±25.4 | 0.483 |
| Social life function | 36.2±17.4 | 31.4±19.2 | 0.296 |
| Mental health | 41.2±19.5 | 42.4±18.8 | 0.806 |
| SF-36 | |||
| MCS | 47.6±9.7 | 45.1±10.0 | 0.321 |
| PCS | 18.4±14.0 | 9.3±14.2 | 0.013 |
Data are shown as mean±standard deviation (SD). *P<0.05.
BMI, body mass index; HU, Hounsfield unit; JOABPEQ, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire; MCS, mental component summary; PCS, physical component summary; RA, rheumatoid arthritis; SF, Short Form Health Survey
Medications for osteoporosis
Preoperatively, two patients (10.0%) employed bisphosphonates in the fracture group, whereas two patients (2.9%) used bisphosphonates in the nonfracture group. Postoperatively, in the fracture group, five patients (25.0%) used bisphosphonate, one patient (5.0%) used vitamin D supplementation, and two patients (10.0%) used teriparatide. In the nonfracture group, five patients (7.4%) used bisphosphonates, five patients (7.4%) used vitamin D supplementation, one patient (1.5%) used denosumab, one patient (1.5%) used selective estrogen receptor modulators, and two patients (2.9%) used teriparatide. No significant differences between the groups, both preoperatively (P=0.221) and postoperatively (P=0.120), were found.
Clinical outcomes
Fig. 2, 3 present the clinical course of the JOABPEQ and PCS and MCS scores on the SF-36 between the fracture and nonfracture groups. Comparative analysis indicated that throughout the study period, the clinical course of low back pain score on the JOABPEQ (P=0.017) and PCS score on the SF-36 (P=0.012) was significantly worse in the fracture group than in the nonfracture group. Moreover, spinal parameters including SVA (P=0.001), TK (P=0.002), and PT (P=0.010) were significantly worse in the fracture group than in the nonfracture group throughout the study period (Table 2). Significant differences were found in 2-year postoperative SVA (49.4 vs. 17.3 mm, P=0.005) and PT (29.0° vs. 24.1°, P=0.016) and in 5-year postoperative SVA (78.4 vs. 30.1 mm, P<0.001), TK (35.2° vs. 22.3°, P=0.010), and PT (30.2° vs. 24.9°, P=0.021) between the fracture and nonfracture groups. None of the preoperative spinal parameters showed a significant difference between the groups.
Figure 2.
JOABPEQ scores preoperatively and 1, 2, and 5 years postoperatively following lumbar fusion surgery. Repeated-measures analysis of variance (ANOVA). HU, Hounsfield unit; JOABPEQ, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire; Pre, preoperative; Post, postoperative
Figure 3.
PCS and MCS scores of SF-36 preoperatively and 1, 2, and 5 years postoperatively following lumbar fusion surgery. Repeated-measures analysis of variance (ANOVA). MCS, mental component summary; PCS, physical component summary; SF, Short-Form Health Survey; Pre, preoperative; Post, postoperative
Table 2.
Comparison of Spinal Alignment between Nonfracture and Fracture Groups Preoperatively and 2 and 5 Years Postoperatively after Lumbar Fusion Surgery.
| Nonfracture (n=68) | Fracture (n=20) | P value | |
|---|---|---|---|
| SVA (mm) | *0.001 | ||
| Pre | 23.5±36.0 | 29.6±33.1 | 0.491 |
| Post 2Y | 17.3±38.1 | 49.4±42.4 | 0.005 |
| Post 5Y | 30.1±44.7 | 78.4±47.1 | <0.001 |
| TK (°) | *0.002 | ||
| Pre | 19.6±9.3 | 24.3±14.3 | 0.184 |
| Post 2Y | 20.4±7.6 | 28.6±17.2 | 0.053 |
| Post 5Y | 22.3±8.7 | 35.2±19.7 | 0.010 |
| PT (°) | *0.010 | ||
| Pre | 25.5±6.0 | 27.0±7.8 | 0.444 |
| Post 2Y | 24.1±4.8 | 29.0±8.1 | 0.016 |
| Post 5Y | 24.9±6.0 | 30.2±8.9 | 0.021 |
| LL (°) | *0.138 | ||
| Pre | 34.1±12.4 | 28.5±13.7 | 0.119 |
| Post 2Y | 34.8±11.3 | 32.3±11.1 | 0.383 |
| Post 5Y | 33.0±11.2 | 28.2±14.2 | 0.178 |
| PI-LL (°) | *0.350 | ||
| Pre | 17.0±12.2 | 20.0±14.2 | 0.417 |
| Post 2Y | 15.4±11.6 | 16.7±13.1 | 0.705 |
| Post 5Y | 16.7±11.2 | 20.7±14.3 | 0.262 |
Repeated-measures analysis of variance (ANOVA).
* Comparison between nonfracture and fracture groups throughout the study period.
LL, lumbar lordosis; PI, pelvic incidence; Pre, preoperative; Post, postoperative; PT, pelvic tilt; SVA, sagittal vertical axis; TK, thoracic kyphosis
Multiple regression analysis adjusted for age, sex, and BMI indicated that incident OVFs were significantly correlated with the following 5-year postoperative spinal parameters: SVA (P=0.009), TK (P=0.002) (Table 3). Moreover, multiple regression analysis demonstrated that AVF was significantly correlated with worse 5-year postoperative low back pain (P=0.005), mental health score (P=0.042) on the JOABPEQ and PCS score on the SF-36 (P=0.025) (Table 4), and spinal alignment including SVA (P=0.009), LL (P=0.013), and PI-LL (P=0.002) (Table 3).
Table 3.
Association of Spinal Parameters 5 Years Postoperatively with the Incident OVFs and AVF Using Multiple Linear Regression Analysis.
| Incident OVFs | Adjacent vertebral fracture | |||
|---|---|---|---|---|
| β* (95% CI) | P value | β* (95% CI) | P value | |
| Radiographic parameter | ||||
| SVA (mm) | 33.3 (8.6 to 58.0) | 0.009 | 64.8 (16.5 to 113.1) | 0.009 |
| TK (°) | 10.9 (3.9 to 18.0) | 0.002 | −1.2 (−15.1 to 12.5) | 0.853 |
| PT (°) | 3.7 (−0.3 to 7.6) | 0.069 | 4.1 (−3.6 to 11.8) | 0.295 |
| LL (°) | −3.6 (−9.9 to 2.6) | 0.249 | −15.5 (−27.7 to −3.3) | 0.013 |
| PI-LL (°) | 0.9 (−5.4 to 7.3) | 0.765 | 19.2 (6.8 to 31.7) | 0.002 |
* Adjusted for age, sex, and BMI.
AVF, adjacent vertebral fracture; BMI, body mass index; Cl, confidence interval; LL, lumbar lordosis; OVFs, osteoporotic vertebral fractures; PI, pelvic incidence; PT, pelvic tilt; SVA, sagittal vertical axis; TK, thoracic kyphosis
Table 4.
Association of Clinical Scores 5 Years Postoperatively with the Incident OVFs and AVF Using Multiple Linear Regression Analysis.
| Incident OVFs | Adjacent vertebral fracture | |||
|---|---|---|---|---|
| β* (95% CI) | P value | β* (95% CI) | P value | |
| JOABPEQ | ||||
| Lumbar function | −2.1 (−21.8 to 17.5) | 0.827 | −36.8 (−75.6 to 1.9) | 0.062 |
| Low back pain | −1.2 (−17.2 to 14.8) | 0.885 | −44.7 (−76.2 to −13.3) | 0.005 |
| Walking ability | −1.3 (−20.1 to 17.3) | 0.884 | −35.5 (−72.6 to 1.6) | 0.060 |
| Social life function | −1.1 (−16.1 to 14.0) | 0.889 | −20.5 (−50.5 to 9.3) | 0.174 |
| Mental health | −6.5 (−18.3 to 5.2) | 0.270 | −24.1 (−47.4 to −0.9) | 0.042 |
| SF-36 | ||||
| PCS | −2.8 (−11.7 to 6.2) | 0.539 | −19.7 (−37.0 to −2.4) | 0.025 |
| MCS | 0.1 (−5.1 to 5.3) | 0.973 | −9.1 (−19.3 to 1.1) | 0.080 |
* Adjusted for age, sex, BMI, and each preoperative score.
AVF, adjacent vertebral fracture; BMI, body mass index; Cl, confidence interval; JOABPEQ, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire; MCS, mental component summary; OVFs, osteoporotic vertebral fractures; PCS, physical component summary; SF, Short Form Health Survey
Finally, the optimal threshold for the HU value for predicting the incidence of OVFs within 5 years postoperatively was determined to be 83.0 (area under the curve 0.701, sensitivity 65.0%, and specificity 79.4% (Fig. 4)).
Figure 4.
ROC curve representing the correlation between the HU values and the incidence of vertebral fractures within 5 years postoperatively. HU, Hounsfield unit; ROC, receiver operator characteristic
Discussion
This study demonstrated that the clinical course of low back pain score on the JOABPEQ, PCS score on the SF-36, and spinal alignment including SVA, TK, and PT was significantly worse in the fracture group than in the nonfracture group throughout the study period. Multiple linear regression revealed a significant correlation between incident OVFs and worse 5-year postoperative spinal alignment including SVA and TK. Furthermore, AVF were significantly correlated with worse low back pain and mental health score on the JOABPEQ, PCS score on the SF-36, and spinal alignment including SVA, LL, and PI-LL, regardless of age, sex, BMI, and each preoperative score. To the best of our knowledge, this study was the first to investigate the impact of incident OVFs on midterm clinical outcomes, HRQOL, and spinal alignment after lumbar fusion surgery.
Overall, patients with OVFs reported high pain intensity and disability, as well as impaired physical function in their daily activities, leading to a reduction in their overall quality of life14,15). Our study revealed that throughout the study period, the fracture group following SSF had significantly worse scores for low back pain on the JOABPEQ and PCS on the SF-36. These results underscore the importance of preventing incident OVFs after SSF to enhance the clinical outcomes of fusion surgery. Additionally, Inose et al. evaluated 166 female patients with OVFs and concluded that the JOABPEQ mental scores were significantly lower in patients with persistent pain 48 weeks after OVFs16). Another study revealed that living with vertebral compression fractures means living with fear and concerns, which results in a loss of self-confidence and an increased sense of confinement17). Additionally, Silverman et al. reported that physical function, emotional status, symptoms, and overall HRQOL evaluated using the Osteoporosis Assessment Questionnaire significantly decreased with the number of vertebral fractures in postmenopausal women during a 3-year study period18). These reports supported that OVFs have a negative impact on mental health and HRQOL. Our study suggested that vertebral fractures, especially AVF, may be associated with the JOABPEQ mental health score and HRQOL. Consequently, spine surgeons should be attentive to the incidence of vertebral fractures, including AVF, and monitor not only the physical aspects but also the mental well-being of patients following lumbar fusion surgery.
This study further demonstrated that spinal alignment including SVA, TK, and PT was significantly worse in the fracture group than in the nonfracture group throughout the study period. Moreover, after adjusting for age, sex, and BMI, incident OVFs were significantly correlated with worse 5-year postoperative SVA and TK. Hori et al. reviewed 70 patients who underwent SSF and reported that sagittal spinal imbalance significantly impacts the surgical outcomes of lumbar fusion surgery8). Youn et al. also analyzed 69 patients with degenerative spinal disease who underwent short-segment lumbar fusions and reported that postoperative improvement of SVA was well correlated with good clinical outcomes9). The findings of this study propose that the incident OVFs and AVF negatively impact spinal alignment, which could also lead to poor surgical outcomes of lumbar fusion surgery. Therefore, vertebral fractures following lumbar fusion surgery must be prevented.
Although preoperative assessment of osteoporosis is considered essential, Pantoja et al. have reported that only 19.6% of spine surgeons screened patients for osteoporosis preoperatively19). Dual-energy X-ray absorptiometry (DEXA) is commonly used to assess bone mineral density (BMD)4). However, DEXA is not routinely performed in several institutions, which include ours. Scott reported that HU may be an alternative to DEXA and can minimize costs and resource utilization20). HU measurements of the spine have been positively correlated with DEXA estimates of BMD in a skeletal model12). Therefore, we assessed osteoporosis using HU values obtained from preoperative lumbar CT scans. In this study, the HU value was significantly lower in the fracture group than in the nonfracture group, and the HU value's optimal threshold for the incidence of vertebral fractures within 5 years postoperatively was found to be 83. A recent best practice guideline based on the consensus of a multidisciplinary panel of experts reported the assessment and treatment of poor bone health before elective spinal reconstructive surgery21). Similarly, for SSF surgery, it has been recommended that patients at risk of vertebral fractures, such as those with HU values below 83, should receive osteoporosis treatment. This approach aims to reduce the risk of postoperative incident vertebral fractures and subsequently prevent poor midterm clinical outcomes and spinal alignment after lumbar spine surgery.
Limitations
Our study's most significant limitation is that we could not precisely determine when incident vertebral fractures occurred within 5 years after SSF because we evaluated vertebral fractures based on plain lateral radiographs of the whole-spine preoperatively and at 5 years postoperatively. Additionally, in this study, only 29% (26 of 88 patients) used medications for osteoporosis. Barton et al. reported that 73% of patients with new vertebral fractures were not treated with osteoporosis drugs22). Although medication usage for osteoporosis was not very low in this study, a higher medication usage could lead to different results. Finally, this study was conducted at a single institute, with a small sample size, and a follow-up rate that is moderately low at 59.8%.
In conclusion, the present study highlights that the fracture group consistently exhibited significantly poorer clinical outcomes, characterized by low back pain scores on the JOABPEQ, PCS score on the SF-36, and spinal alignment including SVA, TK, and PT throughout the study period. Multiple linear regression revealed a significant correlation between incident OVFs and worse 5-year postoperative spinal alignment including SVA and TK. Moreover, AVF was significantly correlated with worse low back pain and mental health score on the JOABPEQ, PCS score on the SF-36, and spinal alignment including SVA, LL, and PI-LL. Hence, it is recommended that patients at risk of vertebral fractures, especially those with an HU value below 83, should take measures to prevent vertebral fractures after lumbar fusion surgery, as this could help prevent the deterioration of midterm postoperative clinical outcomes and spinal alignment.
Conflicts of Interest: The authors declare that there are no relevant conflicts of interest.
Sources of Funding: None declared.
Author Contributions: All authors participated in interpreting the results, writing the report, and approving the final version of the manuscript.
Ethical Approval: The study protocol was approved by the institutional review board of Osaka City General Hospital (Approval number: 1912112).
Informed Consent: All study participants provided informed consent.
Acknowledgement
We would like to thank Editage (www.editage.com) for English language editing.
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