Can abdominal aortic calcification detected on lateral lumbar radiography predict instrument-related complications in patients undergoing posterior lumbar fusion?

Article information

J Korean Soc Geriatr Neurosurg. 2024;20(2):46-51
Publication date (electronic) : 2024 October 17
doi : https://doi.org/10.51638/jksgn.2024.00073
1Department of Neurosurgery, Bundang Jaesaeng General Hospital, Seongnam, Korea
2Department of Neurosurgery, Ajou University College of Medicine, Suwon, Korea
Corresponding Author: Hyung Cheol Kim, MM Department of Neurosurgery, Bundang Jaesaeng General Hospital, 20 Seohyeon-ro 180beon-gil, Bundang-gu, Seongnam 13590, Korea Tel: +82-31-779-0000; Fax: +82-31-779-0163; E-mail: ns.kimhc@gmail.com
Co-Corresponding Author: Pyung Goo Cho, PhD Department of Neurosurgery, Ajou University College of Medicine, 206 World cup-ro, Yeongtong-gu, Suwon 16499, Korea Tel: +82-31-219-4646; Fax: +82-31-219-4657; E-mail: nsdrcpg@gmail.com
Hyung Cheol Kim and Pyung Goo Cho contributed equally to this work as co-corresponding authors.
Received 2024 July 8; Revised 2024 July 31; Accepted 2024 August 6.

Abstract

Objective

Abdominal aortic calcification (AAC) is well known as a useful and simple clinical indicator of the risk of fracture and cardiovascular disease. However, no studies have directly compared the postoperative implications of AAC in spinal surgery. The purpose of this study was thus to examine whether extended AAC (scores ≥5) negatively affected clinical outcomes after posterior lumbar fusion with instrumentation for degenerative lumbar stenosis or degenerative spondylolisthesis.

Methods

The subjects comprised 101 consecutive patients with spinal stenosis or degenerative spondylolisthesis who underwent posterior lumbar fusion and instrumentation between January 2016 and January 2019 and were followed for over 2 years. Propensity score matching was employed to assemble patient groups with similar baseline characteristics. Postoperative complications and radiologic outcomes were compared between the groups (33 patients in each) divided by extended AAC score.

Results

The incidence rates of junctional failure (6.1% vs. 30.3%, P=0.008) and screw-related complications (12.1% vs. 36.4%, P=0.019) were higher in the extended AAC group than in the mild AAC group. However, the rates of adjacent segment disease (24.2% vs. 36.4%, P=0.283) and revision (6.1% vs. 9.1%, P=0.642) were not significantly different between the 2 groups. In terms of postoperative medical complications, cardiovascular and cerebrovascular diseases were significantly more common in the extended AAC group than in the mild AAC group (0% vs. 15.2%, P=0.020).

Conclusion

Extended AAC indicates increased risk for postoperative junctional failure and screw-related complications, regardless of age, osteoporosis, and comorbidities.

Introduction

Bone metabolism involves a continual cycle of bone growth and resorption orchestrated by the dynamic relationship between osteoclasts, osteoblasts, and an array of hormonal and regulatory factors [1,2]. Several studies demonstrate an impact of bone turnover on the development of arterial calcification, and there is some evidence of reduced progression of vascular calcification (VC) with improvements in bone status [3].

VC can be the most dramatic consequence of chronic kidney disease. In the past, VC was thought to be a passive process of crystallization caused by an increase in calcium and phosphorus and their deposition on blood vessel walls. However, in the last 10 years, considerable progress has been made in identifying the mechanisms of VC. VC is an actively regulated process caused by a decrease in various calcification inhibitors, such as fetuin-A, pyrophosphate, matrix glycoprotein, BMP-7, genetic polymorphisms in these factors [4,5], old age, dialysis, and mineral bone metabolism abnormalities [6]. The process of VC is associated with increased arterial stiffness [7,8] and is a risk factor for cardiovascular events such as increased cardiac afterload and congestive heart failure.

Calcium and phosphorus concentrations significantly correlated with arterial calcification, and a non-significant association between bone mineral density (BMD) and arterial calcification has been reported [9]. In contrast, markers of bone turnover, such as P1NP, in patients on hemodialysis negatively correlate with calcification scores. Low markers of bone turnover can mediate impaired bone metabolism and exacerbate the body’s inflammatory response, leading to VC and increasing the risk of hemodialysis-related VC [10].

Previous studies have shown that osteoporosis is associated with proximal junction failure after spinal surgery [11]. Additionally, low BMD is an important risk factor for proximal junctional failure (PJF), and surgeons should consider prophylactic treatment when correcting adult spinal deformity (ASD) in patients with low BMD [12]. Regarding the association between arterial calcification observed on radiography and complications after spinal surgery in patients with osteoporosis, we have investigated this association.

Previous studies have revealed an association between abdominal aortic calcification (AAC) and complications after spinal surgery. For example, one study reported that calcification of the abdominal aorta can predict poor prognosis in patients who have undergone posterior decompression surgery [13]. Another study reported that AAC had a significant negative effect on the incidence of ASD after lumbar fusion. This finding reveals impaired blood flow due to atherosclerosis can exacerbate degenerative changes in adjacent segments [14].

This study investigated whether AAC could affect complications such as ASD after lumbar fusion, along with complications related to screws and cages.

Purpose

AAC is a useful and simple clinical indicator of the risk of fractures and cardiovascular diseases [11,15,16]. However, no studies have directly compared AAC’s postoperative effects in spinal surgery. Thus, this study aimed to examine whether extended AAC (≥5 scores) negatively affects clinical outcomes after posterior lumbar fusion with instrumentation for degenerative lumbar stenosis or spondylolisthesis.

Material and Method

ASD is a broad term that encompasses many complications of spinal fusion, including listhesis, instability, herniated nucleus pulposus, stenosis, hypertrophic facet arthritis, scoliosis, and vertebral compression fractures [17]. In this study, patients with listhesis, instability, herniated nucleus pulposus, and stenosis observed on retrospective images were included as patients with ASD.

Proximal junctional kyphosis (PJK) and PJF are complications of long-instrumented posterior fusion for ASD surgery. PJK is a radiological phenomenon of adjacent segment pathology and involves ongoing adjacent segmental problems at the transition between the fused and mobile segments. PJK has a spectrum of disease severity, ranging from no clinical symptoms to clinical symptoms that may require revision surgery. PJF is a progressive process in the spectrum of PJK and involves structural failures, such as vertebral body fracture, posterior ligament complex, or both, and vertebral subluxation. Patients with PJF may present with higher morbidities, including pain, neurological deficits, and revision surgery [18]. In this study, patients with vertebral body fractures and posterior ligament complex injuries observed on retrospective imaging were included as patients with junctional failures.

The subjects of this study comprised 101 consecutive patients with spinal stenosis or degenerative spondylolisthesis who underwent posterior lumbar interbody fusion and instrumentation between January 2018 and January 2020 and were followed for ≥2 years. Propensity score matching was used to assemble patient groups with similar baseline characteristics. Postoperative complications and radiologic outcomes were compared between the groups (each 33 patients) and were further investigated for associations with extended AAC scores (≥5 scores). According to the scoring system of Kauppila et al. [19], the AAC score (a surrogate marker of systemic atherosclerosis) was assessed using preoperative lateral radiographs of the lumbar spine.

According to Abdellah’s study of the correlation between AAC and vertebral fracture in an elderly patient cohort, significant results were shown between patients with AAC scores of less than 5 and those with scores of 5 or more. Therefore, this study compared patient groups based on AAC scores above and below 5 (Fig. 1) [15].

Fig. 1.

Assessment of aortic calcification segmentally from a lateral lumbar radiograph. The image is scored 0 for aortic calcifications (both posterior [post.] and anterior [ant.]) in front of the L1 vertebra, 3 for calcifications in front of the L2 vertebra, 1 for calcifications in front of the L3 vertebra, and 6 for calcifications in front of the L4 vertebra.

This retrospective study was approved by the Institutional Review Board of Bundang Jaesaeng General Hospital (DMC 2024-02-007). Informed consent was obtained from all individual participants included in this study.

Results

Each of the 33 control groups that were selected through propensity score matching did not show significant differences in sex (15:18 vs. 20:13, P=0.217), mean age (75.24±4.77 vs. 76.82±7.41, P=0.308), body mass index (25.48±3.62 vs. 26.31±4.15, P=0.390), BMD (−1.63±1.02 vs. −2.06±0.95, P=0.087), osteoporosis (18.2% vs. 33.3%, P=0.157), operative time (312.81±98.91 vs. 329.09±123.80, P=0.561), and estimated blood loss (690.63±458.86 vs. 721.21±502.97, P=0.799) (Table 1).

Factors that were investigated using propensity score matching

The prevalence of junctional failure (6.1% vs. 30.3%, P=0.008) and screw-related complications (12.1% vs. 36.4%, P=0.019) were significantly higher in the extended AAC group than in the mild AAC group. The screw-related complications included screw pull-out, screw fractures, and screw halos. Furthermore, adjacent segment disease (24.2% vs. 36.4%, P=0.283) and revision (6.1% vs. 9.1%, P=0.642) rates did not differ between the 2 groups (Table 2).

Postoperative lumbar complications in our patient cohort

In terms of postoperative medical complications, cardiovascular disease (0% vs. 6.1%, P=0.151), cardiovascular disease (0% vs. 9.1%, P=0.076), surgical site infection (3.0% vs. 3.0%, P=1.000), and renal failure (0% vs. 3.0%, P=0.314) showed no significant differences between patient cohorts. However, cardiovascular and cerebrovascular diseases were significantly more common in the extended AAC group than in the mild AAC group (0% vs. 15.2%, P=0.020) (Table 3).

Postoperative medical complications in our patient cohort

Discussion

Previous research has shown that blood calcium and phosphorus concentrations and various other factors affect AAC [9,20]. Therefore, extended AAC is associated with excessive bone resorption and bone weakening, which frequently leads to device-related complications [21]. In agreement with this correlation, the findings of this study revealed that certain complications, such as postoperative instrument dislocation, can be predicted through a simple lumbar radiography test.

The biggest problems after deformity or multilevel fusion surgery are instrument-related complications, ASD, and nonunion (fusion). Various methods exist to evaluate the risk of these postoperative complications [22], such as a global alignment proportion score [23,24], Scoliosis Research Society-Schwab classification [25], and Roussouly classification [26]. However, these evaluation methods are somewhat complicated, usually performed as a retrospective evaluation after surgery, and are not intuitive, making them difficult to apply in clinical practice. The results of this study can be used to intuitively screen for the possibility of complications after surgery through a simple preoperative plain lumbar radiograph. A similar study used preoperative computed tomography (CT)-based Hounsfield units (HU) in patients with ASD to identify those at high risk for bone PJK. This study showed a significant inverse relationship between the mean HU at the upper instrumented vertebra (UIV) and UIV+1 and the postoperative increase in the PJK angle [27]. Similar to the findings of this study, a previous study showed that the HU value of the UIV or L4 on CT could predict the risk of PJF in female patients with ASD undergoing lumbar interbody fusion [28]. Thus, our findings confirm that complications after posterior lumbar fusion surgery can be predicted with a simple X-ray test, compared to a relatively complex CT scan, and prevent excessive exposure to X-rays.

The findings of this study reveal that it is possible to predict future prognosis and decide whether to perform posterior fusion with a simple preoperative X-ray test. In particular, we confirmed a positive correlation between extended AAC and junctional failure and between extended AAC and screw-related complications. However, there was no significant correlation with medical conditions, such as cardiovascular disease, stroke, or renal failure.

Second, there have been no studies on AAC in spinal surgery, although several studies have shown that AAC is associated with bone metabolism [3,20]. The findings of several studies have demonstrated the impact of bone replacement on the development of arterial calcification, and there is evidence that improvement in bone condition may reduce the progression of VC [3]. This scale is considered a good tool for predicting device-related complications, such as postoperative fusion, screw loosening, and cage migration.

The association between AAC and various internal medical diseases has been partially revealed, with additional research ongoing. Although our study did not show a significant correlation between AAC and other medical conditions, many other studies have shown significant correlations. One study reported a positive correlation between AAC and factors such as old age, high blood pressure, and smoking. Furthermore, AAC is associated with an increased risk of death, coronary heart disease, and stroke. Aortic calcification predicts an increased incidence of cardiovascular events. However, the reason for this association requires further investigation [29]. In situations where AAC is emerging as an important factor that increases cardiovascular death and overall mortality beyond simple bone metabolism, using AAC before spinal surgery is thought to help predict the development of postoperative medical complications or the postoperative course of patients [2931].

The first limitation of this study was that it was impossible to match underlying diseases and laboratory values between groups. For example, more patients in the extended AAC group had renal dysfunction, which can adversely affect postoperative complications independent of AAC. In addition, because the number of comparison groups was small, future studies should include more patients. Finally, this was a study on complications within 2 years of surgery. Thus, further research on complications over a longer period is required.

Conclusion

Extended AAC is an indicator of an increased risk of prevalent postoperative junctional failure and screw-related complications, regardless of age, osteoporosis, or comorbidities. In addition to lumbar fusion, prognosis can be easily predicted through AAC in all surgeries that use instruments, such as deformity surgery. AAC may be helpful in decision-making and preoperative counseling regarding the risks and benefits of surgery.

Notes

Conflict of Interest

No potential conflict of interest relevant to this article was reported.

References

1. Gaudio A, Pennisi P, Bratengeier C, et al. Increased sclerostin serum levels associated with bone formation and resorption markers in patients with immobilization-induced bone loss. J Clin Endocrinol Metab 2010;95:2248–53.
2. Starup-Linde J. Diabetes, biochemical markers of bone turnover, diabetes control, and bone. Front Endocrinol (Lausanne) 2013;4:21.
3. Aaltonen L, Koivuviita N, Seppänen M, et al. Association between bone mineral metabolism and vascular calcification in end-stage renal disease. BMC Nephrol 2022;23:12.
4. Jung JY, Hwang YH, Lee H, et al. Association of AHSG gene polymorphisms and aortic stiffness in peritoneal dialysis patients. Am J Nephrol 2010;31:510–7.
5. Stenvinkel P, Pecoits-Filho R, Lindholm B; DialGene Consortium. Gene polymorphism association studies in dialysis: the nutrition-inflammation axis. Semin Dial 2005;18:322–30.
6. Moe SM, Chen NX. Mechanisms of vascular calcification in chronic kidney disease. J Am Soc Nephrol 2008;19:213–6.
7. Jung JY, Hwang YH, Lee SW, et al. Factors associated with aortic stiffness and its change over time in peritoneal dialysis patients. Nephrol Dial Transplant 2010;25:4041–8.
8. Lee H, Hwang YH, Jung JY, et al. Comparison of vascular calcification scoring systems using plain radiographs to predict vascular stiffness in peritoneal dialysis patients. Nephrology (Carlton) 2011;16:656–62.
9. Chen TY, Yang J, Zuo L, Wang L, Wang LF. Relationship of abdominal aortic calcification with lumbar vertebral volumetric bone mineral density assessed by quantitative computed tomography in maintenance hemodialysis patients. Arch Osteoporos 2022;17:24.
10. Xia X, Liu J, Zhou C, et al. The correlation analysis between plasma sclerostin levels and bone turnover markers and inflammation factors in hemodialysis patients. Chin J Postgrad Med 2022;(36):909–13.
11. Niu Q, Hong Y, Lee CH, Men C, Zhao H, Zuo L. Abdominal aortic calcification can predict all-cause mortality and CV events in dialysis patients: a systematic review and meta-analysis. PLoS One 2018;13e0204526.
12. Yagi M, Fujita N, Tsuji O, et al. Low bone-mineral density is a significant risk for proximal junctional failure after surgical correction of adult spinal deformity: a propensity score-matched analysis. Spine (Phila Pa 1976) 2018;43:485–91.
13. Sakaura H, Ikegami D, Fujimori T, Sugiura T, Owaki H, Fuji T. Abdominal aortic calcification is a significant poor prognostic factor for clinical outcomes after decompressive laminotomy for lumbar spinal canal stenosis. Global Spine J 2019;9:724–8.
14. Sakaura H, Ikegami D, Fujimori T, Sugiura T, Mukai Y, Hosono N. Does atherosclerosis have negative impacts on early adjacent segment degeneration after posterior lumbar interbody fusion? Global Spine J 2021;11:674–8.
15. El Maghraoui A, Rezqi A, Mounach A, Achemlal L, Bezza A, Ghozlani I. Relationship between vertebral fracture prevalence and abdominal aortic calcification in men. Rheumatology (Oxford) 2012;51:1714–20.
16. Osteoporosis JO. Expression of concern on “a radiographic study on the associations of age and prevalence of vertebral fractures with abdominal aortic calcification in Japanese postmenopausal women and men”. J Osteoporos 2022;2022:9798519.
17. Virk SS, Niedermeier S, Yu E, Khan SN. Adjacent segment disease. Orthopedics 2014;37:547–55.
18. Hyun SJ, Lee BH, Park JH, Kim KJ, Jahng TA, Kim HJ. Proximal junctional kyphosis and proximal junctional failure following adult spinal deformity surgery. Korean J Spine 2017;14:126–32.
19. Kauppila LI, Polak JF, Cupples LA, Hannan MT, Kiel DP, Wilson PW. New indices to classify location, severity and progression of calcific lesions in the abdominal aorta: a 25-year follow-up study. Atherosclerosis 1997;132:245–50.
20. Wang TK, Bolland MJ, van Pelt NC, et al. Relationships between vascular calcification, calcium metabolism, bone density, and fractures. J Bone Miner Res 2010;25:2777–85.
21. Park SW, Lee JH, Ehara S, Seong SO, Park JT. Bone resorption around pedicle screws after pedicle screw plate fixation. J Korean Radiol Soc 2003;48:331–5.
22. Teles AR, Aldebeyan S, Aoude A, et al. Mechanical complications in adult spinal deformity surgery: can spinal alignment explain everything? Spine (Phila Pa 1976) 2022;47:E1–9.
23. Ham DW, Kim HJ, Choi JH, Park J, Lee J, Yeom JS. Validity of the global alignment proportion (GAP) score in predicting mechanical complications after adult spinal deformity surgery in elderly patients. Eur Spine J 2021;30:1190–8.
24. Quarto E, Zanirato A, Pellegrini M, et al. GAP score potential in predicting post-operative spinal mechanical complications: a systematic review of the literature. Eur Spine J 2022;31:3286–95.
25. Slattery C, Verma K. Classification in brief: SRS-Schwab classification of adult spinal deformity. Clin Orthop Relat Res 2018;476:1890–4.
26. Zhang H, Hai Y, Meng X, et al. Validity of the Roussouly classification system for assessing distal junctional problems after long instrumented spinal fusion in degenerative scoliosis. Eur Spine J 2022;31:258–66.
27. Yao YC, Elysee J, Lafage R, et al. Preoperative Hounsfield units at the planned upper instrumented vertebrae may predict proximal junctional kyphosis in adult spinal deformity. Spine (Phila Pa 1976) 2021;46:E174–80.
28. Hiyama A, Sakai D, Katoh H, Sato M, Watanabe M. Comparative analysis of hounsfield units and vertebral bone quality scores for predicting proximal junctional failure in female adult spinal deformity patients undergoing planned 2-stage corrective surgery with lateral lumbar interbody fusion. World Neurosurg 2023;177:e775–84.
29. Jayalath RW, Mangan SH, Golledge J. Aortic calcification. Eur J Vasc Endovasc Surg 2005;30:476–88.
30. Bastos Gonçalves F, Voûte MT, Hoeks SE, et al. Calcification of the abdominal aorta as an independent predictor of cardiovascular events: a meta-analysis. Heart 2012;98:988–94.
31. Peeters MJ, van den Brand JA, van Zuilen AD, et al. Abdominal aortic calcification in patients with CKD. J Nephrol 2017;30:109–18.

Article information Continued

Fig. 1.

Assessment of aortic calcification segmentally from a lateral lumbar radiograph. The image is scored 0 for aortic calcifications (both posterior [post.] and anterior [ant.]) in front of the L1 vertebra, 3 for calcifications in front of the L2 vertebra, 1 for calcifications in front of the L3 vertebra, and 6 for calcifications in front of the L4 vertebra.

Table 1.

Factors that were investigated using propensity score matching

AAC <5 AAC ≥5 P-value
Total number 33 33
Sex (male: female) 15:18 20:13 0.217
Mean age (yr) 75.24±4.77 76.82±7.41 0.308
BMI (kg/m2) 25.48±3.62 26.31±4.15 0.390
BMD (T-score) −1.63±1.02 −2.06±0.95 0.087
Osteoporosis 6 (18.2) 11 (33.3) 0.157
Operative time (min) 312.81±98.91 329.09±123.80 0.561
Estimated blood loss (mL) 690.63±458.86 721.21±502.97 0.799

Values are presented as mean±standard deviation or number (%).

AAC, abdominal aortic calcification; BMI, body mass index; BMD, bone mineral density.

Table 2.

Postoperative lumbar complications in our patient cohort

Type of complication AAC <5 (n=33) AAC ≥5 (n=33) P-value
ASD 8 (24.2) 12 (36.4) 0.283
Junctional failure 2 (6.1) 10 (30.3) 0.008
Screw related 4 (12.1) 12 (36.4) 0.019
Cage migration 1 (3.0) 1 (3.0) 1.000
Overall instrument-related 4 (12.1) 12 (36.4) 0.019
Revision 2 (6.1)  3 (9.1) 0.642

Values are presented as number (%).

AAC, abdominal aortic calcification; ASD, adjacent segment disease.

Table 3.

Postoperative medical complications in our patient cohort

Type of complication AAC <5 (n=33) AAC ≥5 (n=33) P-value
Cardiovascular 0 (0) 2 (6.1) 0.151
CVA 0 (0) 3 (9.1) 0.076
CVD (cardiovascular+CVA) 0 (0) 5 (15.2) 0.020
SSI 1 (3.0) 1 (3.0) 1.000
Renal 0 (0)  1 (3.0) 0.314

Values are presented as number (%).

AAC, abdominal aortic calcification; CVA, cerebrovascular accident; CVD, cardiovascular and cerebrovascular disease; SSI, surgical site infection.