Abstract
Posterior fixation with pedicle screws and rods may be required when treating Chance fractures involving the posterior ligamentous complex. Only a few studies have evaluated the outcomes of older adults with Chance fractures. Given that bone mineral density decreases with increasing age, cement augmentation of pedicle screws may be critical in older patients. This study compared the postoperative outcomes of patients aged ≥ 65 with Chance fractures who underwent fixation with or without cement-augmented pedicle screws. This retrospective single-center comparative study included the data of patients enrolled between August 2014 and September 2022. The patients were divided into 3 groups according to whether cement augmentation was employed for pedicle screws. The Cobb angle was measured before and after surgery and at final follow-up. Refractures, adjacent fractures, implant removals, and screw pullouts were recorded. Twenty-one patients with a follow-up duration of ≥ 6 months were included, with 13 and 8 patients in the uncemented and cement-augmented screw groups, respectively. The mean Cobb angles significantly improved in both groups after surgery and the improvements were not different between groups. At final follow-up, the Cobb angle improvement in the uncemented screw group was significantly inferior to that in the cement-augmented screw group. The incidence of screw pullout was significantly higher in the uncemented screw group (69.2% vs 12.5%) and was especially higher in patients with a T-score greater than − 2.5 (87.5%). No between-group differences were noted in refracture, adjacent fracture, and implant removal rates. In patients aged ≥ 65 with Chance fractures, cement-augmented pedicle screws may help to reduce the risk of screw pullout. This effect was most notable in patients with a T-score greater than − 2.5, although this subgroup finding should be interpreted with caution.
Keywords: cement-augmented pedicle screws, Chance fractures, older patients, screw pullout, thoracolumbar fractures
1. Introduction
Spinal fractures are a common consequence of falls and injuries, particularly among older adults. In one Taiwanese study, the prevalence of vertebral fractures in women and men older than 65 years was 20% and 12.5%, respectively.[1] Chance fractures involve all three columns of the spinal architecture and are caused by a flexion–distraction injury.[2] Chance fractures can often be managed conservatively if they involve bony components of the posterior column. In cases of rapid fracture deformity, neural impingement, or chronic pain, surgical intervention may be required. These complications are more likely to occur in fractures involving the posterior ligamentous complex, and these are known as ligamentous Chance fractures. Patients with ligamentous Chance fractures often develop a rapidly progressing kyphotic deformity, and conservative treatment alone frequently results in chronic back pain, underlining the need for surgical intervention in these patients.[3]
Surgical outcomes for thoracolumbar fractures tend to worsen with age, with older patients demonstrating poorer outcomes and higher complication rates compared with younger cohorts.[4] Using cement-augmented pedicle screws significantly improves the mechanical performance of internal fixation, reducing the risk of mechanical failures.[5–8]
Few studies have evaluated the surgical outcomes of Chance fractures in older patients, yet older adults, owing to factors such as osteoporosis and decreased physiological resilience, are disproportionately affected by spinal injuries. Given the negative correlation between age and bone mineral density (BMD),[9] the use of pedicle screws with cement augmentation may be critical to improve the outcomes of older patients with Chance fractures.
In the present study, we retrospectively examined the surgical outcomes and potential complications in patients aged ≥ 65 years who underwent posterior fixation surgery for Chance fractures with uncemented or cement-augmented pedicle screws. Our results are expected to provide new insights into this topic and help improve the surgical outcomes of older patients with Chance fractures.
2. Methods
2.1. Patients
In this retrospective comparative study, we enrolled consecutive patients from January 2014 to December 2022 from a single hospital. This study was performed in accordance with the Declaration of Helsinki. The Institutional Review Board of our institute approved this study (approval no. 2023048) and waived the requirement for informed consent. We included patients aged ≥ 65 years who underwent surgery for Chance fracture of the thoracolumbar spine, where the surgery involved fixation with pedicle screws with or without cement augmentation. We excluded patients with multiple traumas, a history of fracture at the affected level of the Chance fracture, and a follow-up period of < 6 months.
For the surgeries, either a regular cannulated or a fenestrated pedicle screw system was used. Posterior instrumentation was performed either through a standard open surgical technique or a minimally invasive percutaneous method. Both fenestrated and regular cannulated pedicle screw systems were used in this study. In the cement-augmented group, all screws, regardless of type, were augmented with 2 mL of polymethylmethacrylate (PMMA) per screw. The choice of screw type was based on implant availability during the surgical period rather than on specific patient characteristics. Patients receiving uncemented screws did not undergo any PMMA injection. For patients with neurological deficits resulting from their fractures, a limited laminectomy was performed. For fractures lacking anterior support, an additional vertebroplasty was performed.
All patients received the same postoperative care and rehabilitation. We divided the patients into two groups according to whether cement augmentation was employed for pedicle screws (cement-augmented and uncemented screw groups). The choice to use cement augmentation was not based on a predefined protocol. Instead, the decision was made intraoperatively at the discretion of the attending surgeon, based on perceived screw purchase (i.e., tactile feedback during pedicle tapping) and visual assessment of bone quality. In general, cement augmentation was considered when screw purchase appeared inadequate during insertion. In addition, adoption of cement-augmented screws gradually increased over time as part of the evolving surgical strategy at our institution.
2.2. Data collection
The data collected were drawn from medical records and images. Patient-related variables included age, sex, body mass index (BMI), BMD, and time from injury to surgery. BMD is presented using T-scores and categorized into two groups using −2.5 as the cutoff point. Surgical variables included cement augmentation of pedicle screws (yes or no), approach (open or minimally invasive), combined vertebroplasty or decompression (yes or no), number of segments fixed with pedicle screws, and bone grafting (yes or no).
The following findings were evaluated by 1 senior author specialized in the radiology of spinal deformity: sagittal plane Cobb angles at 3 time points, namely preoperative, postoperative, and final follow-up, and evidence of pullout, defined as pedicle screws displaced from their original position by at least 3 mm, as observed in X-ray imaging (yes or no). The study outcomes included refracture, adjacent fracture, implant removal, and screw pullout rates and improvements in the Cobb angle.
2.3. Statistical analysis
All analyses were performed using SPSS (version 28.0.1.0; IBM Corporation, Armonk). Between-group comparisons were performed using a two-sample t test or the Mann–Whitney U test for continuous variables and Fisher exact test for categorical variables. Repeated measures of the Cobb angle of the groups and time points were compared using a generalized estimating equation.
3. Results
Figure 1 presents the patient selection flowchart. We included 21 patients in this study (13 in the uncemented screw group and 8 in the cement-augmented screw group). Table 1 presents their characteristics. The following variables were comparable between the groups: age, sex, BMI, BMD, surgical approach, number of patients who underwent vertebroplasty and bone grafting, number of segments fixed with pedicle screws, days from injury to surgery, and length of follow-up. A significantly higher proportion of patients underwent decompression in the cement-augmented screw group.
Figure 1.
Flowchart of patient selection.
Table 1.
Patient characteristics.
| Uncemented pedicle screw | Cement-augmented pedicle screw | P value | |
|---|---|---|---|
| No. of patients | 13 | 8 | |
| Age | 72.4 ± 5.5 | 78.0 ± 6.7 | .051 |
| Male | 5 (38.5%) | 3 (37.5%) | 1.000 |
| BMI (kg/m2) | 26.8 ± 4.8 | 27.0 ± 4.8 | .693 |
| Bone mineral density (T-score) | |||
| Mean ± SD | −2.2 ± 0.7 | −2.7 ± 0.7 | .146 |
| T-score less than − 2.5 | 5 (38.5%) | 4 (50.0%) | .673 |
| Affected segments | |||
| No. of segments | 14 | 8 | |
| T11 | 1 (7.1%) | 0 | |
| T12 | 6 (43.0%) | 3 (37.5%) | |
| L1 | 3 (21.4%) | 3 (37.5%) | |
| L2 | 3 (21.4%) | 1 (12.5%) | |
| L3 | 1 (7.1%) | 0 | |
| L5 | 0 | 1 (12.5%) | |
| Surgical approach | |||
| Open | 4 (30.8%) | 5 (62.5%) | .203 |
| Minimally invasive | 9 (69.2%) | 3 (37.5%) | |
| Combined with vertebroplasty | 6 (46.2%) | 5 (62.5%) | .659 |
| Combined with decompression | 0 (0.0%) | 3 (37.5%) | .042 |
| Number of segments fixed with pedicle screws | |||
| 2 | 1 (7.7%) | 2 (25.0%) | .174 |
| 3 | 8 (61.5%) | 6 (75.0%) | |
| 4 | 4 (30.8%) | 0 (0.0%) | |
| Bone grafting | 4 (30.8%) | 2 (25.0%) | 1.000 |
| Days from injury to surgery | |||
| Mean ± SD | 17.0 ± 23.9 | 20.6 ± 19.6 | .414* |
| Range | 0–85 | 1–57 | |
| Follow-up (mo) | |||
| Mean ± SD | 39.5 ± 29.7 | 22.9 ± 15.5 | .185* |
| Range | 7.5–105.3 | 6–42.7 | |
Mann–Whitney U test.
The mean postsurgery Cobb angle significantly improved in both groups, and the improvement did not significantly differ between the groups. At final follow-up, the Cobb angle improvement in the uncemented screw group was significantly inferior (P = .018) to that in the cement-augmented screw group (Table 2). Screw pullout was noted in 10 patients at 69.6 ± 59.9 days (range: 31–234) after surgery, and the risk of screw pullout was significantly higher (relative risk: 5.5, P = .024) in the uncemented screw group. No significant between-group differences were observed in the incidence of refracture, adjacent fracture, or implant removal.
Table 2.
Outcomes.
| Uncemented pedicle screw | Cement-augmented pedicle screw | P value | |
|---|---|---|---|
| Cobb angle | |||
| Preoperative | 24.8 ± 16.4 | 21.7 ± 20.8 | .701 |
| Postoperative | 12.1 ± 11.1 | 7.0 ± 19.0 | .569 |
| Final follow-up | 28.1 ± 15.7 | 15.6 ± 20.0 | .018 |
| Screw pullout | 9 (69.2%) | 1 (12.5%) | .024 |
| Refracture | 0 | 0 | 1.000 |
| Adjacent fracture | 0 | 1 (12.5%) | .381 |
| Removal of implant | 3 (23.1%) | 0 | .257 |
Twelve patients had a T-score greater than −2.5. Of them, 8 underwent fixation with an uncemented pedicle screw, and 7 (87.5%) of them experienced screw pullout; the incidence of pullout among these patients was significantly higher (P = .010) than that in the cement-augmented screw group (Table 3).
Table 3.
Stratified analysis.
| T-score | Type of pedicle screw | No. of patients | Screw pullout | P value |
|---|---|---|---|---|
| Greater than −2.5 | Uncemented | 8 | 7 (87.5%) | .010 |
| Cement-augmented | 4 | 0 (0.0%) | ||
| Less than or equal to −2.5 | Uncemented | 5 | 2 (40.0%) | 1.000 |
| Cement-augmented | 4 | 1 (25.0%) |
4. Discussion
Surgical treatment of vertebral fractures in older adults is challenging, and the use of PMMA cement for augmenting fixation has become commonplace. In our cohort of older patients with Chance fractures, compared with uncemented fixation, cement-augmented pedicle screw fixation significantly reduced the risk of screw pullout (from 69.2% to 12.5%, P = .024). Consistent with our findings, El Saman et al[5] demonstrated that cement-augmented pedicle screw fixation in patients with vertebral fractures led to a significantly lower rate of loosening than that in patients with uncemented screws (from 62.9% to 4.3%, P < .001). Notably, our patients had Chance fractures, a type of injury involving all 3 columns, which may be more severe than the thoracolumbar vertebral fractures studied by El Saman et al Taken together, these findings support the use of cement-augmented pedicle screw fixation because it appears to increase stability and may therefore be more effective than uncemented screws for vertebral fractures in older adults.
Notably, all patients in our cohort were older than 65 years. Studies have revealed the effect of age on the outcomes of thoracolumbar fractures. For instance, a 2019 retrospective analysis by Jang et al[10] involving 208 patients identified an age of > 43 years as the most important predictor for implant failure and postoperative vertebral recollapse. In another retrospective review by Hitchon et al[11] in 2014, among 73 patients with thoracolumbar fractures, patients older than 59 years were noted to require posterior fixation in addition to anterolateral fixation. Consequently, further differentiating risk among our patient cohort was difficult, as they all were considered high-risk individuals owing to their age. Future studies should include a wider age range of patients to yield a more granular understanding of risk; identifying an age cutoff beyond which the risk of complications related to Chance fractures might considerably increase would be especially valuable.
We stratified the patients based on BMD (T-score greater than − 2.5 and less than or equal to −2.5). Notably, the subgroup with a better bone quality (T-score greater than − 2.5) exhibited a higher screw pullout rate (58.3% [7/12] vs 33.3% [3/9]). Additionally, we observed a significant difference in the screw pullout rate between the cemented and uncemented screw groups within the T-score greater than − 2.5 subgroup (0% vs 87.5%, P = .010) but not within the T-score less than or equal to −2.5 subgroup. A previous meta-analysis reported that a relative lower BMD is a risk factor for refracture after percutaneous vertebroplasty and kyphoplasty for osteoporotic vertebral compression fractures in Eastern Asia.[12] In our study, while BMD was not identified as a risk factor for screw pullout, our stratification analysis suggested a potential interaction effect between BMD and cement-augmented screws. We observed the highest risk of screw pullout in patients with better bone quality (T-score > −2.5) who received uncemented screws, which is counterintuitive. One possible explanation for the counterintuitive finding is that surgeons may have been reassured by relatively favorable T-scores and therefore opted not to use cement augmentation, even in cases that were mechanically unstable due to unmeasured factors such as fracture morphology or local bone architecture. Additionally, T-scores obtained from dual-energy X-ray absorptiometry, often taken at the hip or spine, may not accurately reflect bone quality at the specific vertebral level affected by the fracture. This stratified analysis was based on very small subgroups, and the possibility of a Type I error cannot be excluded. Therefore, these findings should be interpreted with caution and regarded as exploratory. Future studies should include populations with a broader range of BMD, which might help identify a potential cutoff value for the risk of surgical complications related to Chance fractures.
Whether to perform spinal lordosis correction demands a meticulous evaluation because undercorrection can exacerbate kyphosis and lead to complications such as chronic back pain. Seo et al suggested that a postoperative Cobb angle > 10.5° can lead to unsatisfactory outcomes.[13] However, the optimal timing of surgical intervention remains unclear, although studies have indicated that early surgery – within 72 hours – may improve outcomes. Our results revealed that older patients typically favored initial conservative treatment, which frequently led to delayed surgical intervention and exacerbated the kyphotic deformities to be dealt with during surgery. In this study, the mean interval from injury to surgery ranged from 17 to 20 days, further supporting the observation of delayed operative timing in this population. The possibility of spinal kyphosis correction was thus diminished, which may have led to poorer patient outcomes.
Our study provides valuable insights into the management of Chance fractures in older adults. However, our findings should be interpreted in the context of its limitations. One such limitation is the trend toward older age in the cement-augmented group (mean 78.0 vs 72.4 years, P = .051). Although not statistically significant, this age difference may have influenced the decision to use cement augmentation and could reflect differences in underlying bone quality or surgeon perception of screw fixation risk. Moreover, the absence of a matched-group design decreased the comparability between groups, particularly in the imbalance in decompression rates. This may reflect baseline differences in clinical severity, such as neurological status or fracture instability, which could have influenced both the decision to perform decompression and to use cement augmentation. While the allocation of cement use was based on intraoperative judgment rather than preoperative criteria, this introduces a risk of selection bias and confounding by indication. These limitations, inherent in retrospective surgical studies, must be considered when interpreting the treatment effects observed. Additionally, the small sample size increased the risk of false negatives; however, we still observed a significant association in cement-augmented pedicle screw usage. The small subgroup sizes in the stratified BMD analysis also increase the risk of a Type I error, and the findings from that analysis should be interpreted as exploratory. No formal sample size calculation was conducted due to the retrospective nature of the study. Additionally, the small sample size precluded the use of multivariate analyses, limiting our ability to adjust for potential confounders such as differences in decompression rates. Furthermore, we were unable to conduct the further analysis to assess the interaction among variables due to the limited number of cases. In summary, caution is warranted when interpreting these results due to the aforementioned limitations. Future larger-scale and more comprehensive studies encompassing a broader range of BMD are needed to validate our findings.
5. Conclusion
Our findings provide preliminary evidence that cement-augmented pedicle screws may reduce the risk of screw pullout in older patients undergoing surgery for Chance fractures. We observed a higher incidence of screw pullout among patients with better bone quality. These findings highlight the complexity of managing such injuries and underscore the need for further investigations that incorporate a broader BMD spectrum, thereby helping to optimize treatment strategies and further enhance patient outcomes.
Author contributions
Conceptualization: Lin-Yu Chao.
Formal analysis: Chang-Hao Lin.
Investigation: Yi-Hsiang Liao, Chang-Hao Lin.
Methodology: Yi-Hsiang Liao, Lin-Yu Chao.
Supervision: Lin-Yu Chao.
Writing – original draft: Yi-Hsiang Liao.
Writing – review & editing: Chang-Hao Lin, Yi-Hung Huang, Cheng-Yi Wu, Chen-Hao Chiang, Lin-Yu Chao.
Abbreviations:
- BMD
- bone mineral density
- BMI
- body mass index
- PMMA
- polymethylmethacrylate
The authors are solely responsible for the content of this article, which reflects their own research and experience.
The views expressed do not necessarily represent those of their affiliated institutions.
The authors have no funding and conflicts of interest to disclose.
The datasets generated during and/or analyzed during the current study are not publicly available, but are available from the corresponding author on reasonable request.
How to cite this article: Liao Y-H, Lin C-H, Huang Y-H, Wu C-Y, Chiang C-H, Chao L-Y. Fixation of Chance fractures with cement-augmented pedicle screws reduces the risk of screw pullout in older patients: A retrospective comparative study. Medicine 2025;104:40(e44987).
Contributor Information
Yi-Hsiang Liao, Email: yihsiang18may@gmail.com.
Chang-Hao Lin, Email: cych12763@gmail.com.
Yi-Hung Huang, Email: cychaudiofan@gmail.com.
Cheng-Yi Wu, Email: i54921598@gmail.com.
Chen-Hao Chiang, Email: chiangabaca@gmail.com.
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