Clinical effect of treating hyperextension injuries of the thoracolumbar spine in patients with ankylosing spondylitis, without active intervention on the anterior distraction defect

doi:10.21203/rs.3.rs-4941835/v1

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Clinical effect of treating hyperextension injuries of the thoracolumbar spine in patients with ankylosing spondylitis, without active intervention on the anterior distraction defect

https://doi.org/10.21203/rs.3.rs-4941835/v1

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Background

To observe the treatment effect of hyperextension fracture on thoracolumbar in patients with ankylosing spondylitis (AS) and determine whether anterior distraction defect can achieve union without active intervention.

Methods

From 2013 to 2023, we retrospectively searched our database to identify all individuals who had experienced extension-type fractures in the thoracolumbar region. The patients received either surgical or conservative management for treatment. The assessment of the extent of the anterior distraction defect was conducted in all patients. The evaluation of clinical effectiveness mainly involves the utilization of the visual analogue scale (VAS) to measure the severity of back pain and the Oswestry Disability Index (ODI) to assess functional limitations. Computed tomography imaging is used to assess the progress of fracture healing.

Results

A total of 32 individuals diagnosed with AS received medical treatment for thoracolumbar hyperextension fractures at our institution and met the inclusion criteria. All patients were followed up for a minimum of 12 months, with an average age of 58.7 ± 13.1 years. The mean extent of the anterior distraction defect was 10.3 (5.4, 16.1) mm, with 18 (56.3%) patients exhibiting an anterior defect extent exceeding 10 mm. All the patients expressed satisfaction with the outcomes, and all patients exhibited successful healing of their fractures. The mean VAS and ODI values were recorded as 1 (0, 2) and 9 (4, 9) %, respectively, during the final follow-up. Compared to surgery patients, the anterior defect was smaller in patients who received conservative treatment (P > 0.05). The anterior defect was larger after the operation compared to preoperative, but there was no statistically significant difference (P > 0.05). No significant complications or deaths occurred during the treatment, except for one patient who experienced a delayed neurologic deficit.

Conclusion

Both surgical and conservative treatments can achieve favorable outcomes in patients with AS accompanied by thoracolumbar hyperextension fracture. Regarding the anterior distraction defect resulting from hyperextension, fracture healing can be achieved without active intervention.

Ankylosing spondylitis

thoracolumbar fractures

hyperextension injury

distraction defect

surgical stabilization

conservative treatment

Ankylosing Spondylitis (AS) is a chronic inflammatory disease characterized by biomechanical alterations of the spine and progressive stiffness[1]. In advanced AS, patients often develop ossification of soft tissue lesions, which leads to spine fusion, osteoporosis, spinal deformities, and produces a characteristic radiographic appearance known as bamboo spine[1, 2]. Therefore, patients with AS are more susceptible to sustaining fractures even with minimal energy mechanisms[3]. Due to the ankylosing ossification of the anterior and posterior elements, most fractures exhibit a significant degree of instability, affecting all three columns that comprise the spine[4, 5].

Hyperextension fractures are the most common type of thoracolumbar spine fracture in patients with AS[4–6]. According to the AOSpine classification, the incidence of B3-type fractures ranges from approximately 20–64%[2, 4, 7]. In these anterior distraction fractures, the two ends of the fracture are separated, resulting in the formation of an anterior distraction defect that may impede fracture healing[8]. Currently, surgical stabilization is the preferred treatment for managing thoracolumbar fractures in individuals diagnosed with AS[2, 4, 9, 10]. However, the efficacy of conservative treatment cannot be completely ignored as approximately one-third of patients choose it[11, 12]. Regardless of the treatment modality, achieving effective reduction of hyperextension fractures presents a considerable challenge due to the rigidity of the spine and pre-existing kyphotic deformity[5, 13]. Therefore, for anterior defects caused by distraction fractures, is bone graft fusion or active fracture reduction necessary?

It is well known that AS possesses a strong osteogenic ability, and adequate stabilization is crucial for the healing of fractures[14–16]. Some studies have also confirmed that anterior column defects can achieve bone union without the need for bone grafts or cages in AS patients with thoracolumbar pseudarthrosis[14, 17, 18]. Additionally, some studies have suggested that although achieving a reduction of hyperextension injury is challenging during surgery, postoperative mobilization can spontaneously restore the sagittal profile of the fracture and reduce the extent of the anterior defect by compressing the fracture site[5, 13]. However, for hyperextension fractures, few studies have reported the extent of the anterior distraction defect and whether natural union can be achieved.

The objective of this investigation was to assess the clinical and radiological outcomes following surgical stabilization or conservative treatment for hyperextension injuries affecting the thoracolumbar spine, without bone graft fusion or active fracture reduction for the anterior distraction defects. Additionally, it is questionable whether a patient with a large anterior defect can achieve union without active intervention. Therefore, we assessed the extent of the anterior defects caused by hyperextension injury to provide a reference for future clinical treatment.

This study was retrospectively conducted at a single institution and received approval from the Institutional Review Board, with all patients providing informed consent. We retrospectively searched our database to identify all individuals who exhibited extension-type fractures in the thoracolumbar region between February 2013 and April 2023. Demographic data collected included age, gender, trauma history, fracture level, neurological status, and the extent of the anterior defect (Table 1). The diagnosis of AS was confirmed by the rheumatologist through a comprehensive evaluation, which included clinical observations and radiographic assessments. The fracture types were classified using the AOSpine classification. The evaluation of neurological disabilities was performed using the grading system developed by the American Spinal Injury Association (ASIA).

Table 1 Patient demographics and case details

All participants

Operative

Nonoperative

P value

No. of patients

Age (yr)

Sex

Male

Female

Mechanism of injury

Low-energy (e.g., ground-level fall)

High-energy (e.g., high-speed MVA)

ASIA grade

Anterior defect (mm)

58.7±13.1

10.3(5.4, 16.1)

61.3±13.9

12.7±9.9

53.6±10.2

9.3±4.6

0.118

0.593

0.442

0.695

0.289

MVA, motor vehicle accident; ASIA, American Spinal Injury Association

The anterior distraction defect is defined as the line located at the anterior of the fractured end of the thoracolumbar spine or as the maximum height of the bony defect in sagittal view on CT scans[8, 17]. The treatment methods include surgical and conservative approaches. Surgical treatment is recommended for this type of thoracolumbar hyperextension fracture in AS, especially in patients with nerve damage; however, the final decision regarding treatment rests with the patient. Surgical treatment is mainly based on posterior long-segment surgical fixation, while conservative treatment generally includes three months of bed rest, bracing, and the use of anti-inflammatory drugs. The efficacy of anti-osteoporosis drugs as a treatment for secondary osteoporosis of AS has been found to be insignificant in various studies[19, 20]. Therefore, instead of routinely administering anti-osteoporosis therapy, we recommended that the patient receive further treatment for AS in the rheumatology department after fracture treatment.

Inclusion and exclusion criteria

The criteria for inclusion were as follows: 1. AS was diagnosed using the modified New York criteria; 2. the imaging findings were hyperextension fractures of thoracolumbar; 3. the patient received either surgical or conservative management for treatment; 4. patients were followed up, and imaging data was available. The criteria for exclusion were as follows: 1. the fractures were not hyperextension fractures of thoracolumbar; 2. the patients failed to follow up for various reasons.

Follow-up evaluation

The evaluation of clinical effectiveness mainly involves the utilization of the visual analogue scale (VAS) to measure the severity of back pain and the Oswestry Disability Index (ODI) to assess functional limitations. Bone healing is defined as the formation of bridging bone or the appearance of a trabecular pattern on computed tomography scans at the site of the fracture[4, 21]. Complications, including internal fixation failure in surgical patients, were recorded during treatment. The neurological status changes were assessed using the ASIA classification system.

Statistical analysis

Numerical values and percentages were used to present qualitative variables, whereas the mean ± standard deviation or median was employed to express quantitative variables. Differences in categorical variables were assessed using Pearson's chi-square test. Preoperative and postoperative measurements were compared using paired sample t-tests, with a significance level set at P < 0.05. The statistical analyses were conducted using IBM SPSS Statistics 27.0 software.

During the study period, a total of 36 individuals diagnosed with AS received medical treatment for thoracolumbar hyperextension fractures at our institution, and 32 (88.9%) of them met the inclusion criteria for this study. The average age was 58.7 ± 13.1 years (range 29–83 years). All patients were followed up for a minimum of 12 months, with an average follow-up duration of 55.9 ± 38.8 months. The majority of patients were males (87.5%), and low-energy injury (65.6%) was the primary mechanism of injury. Upon their hospital admission, four patients (12.5%) experienced varying degrees of neurological deficits, including three patients with ASIA C and one patient with ASIA D. The mean extent of the anterior distraction defect was 10.3 (5.4, 16.1) mm, with 18 (56.3%) patients exhibiting an anterior defect extent exceeding 10 mm.

The surgical approach was employed in the treatment of 21 (65.6%) patients, while conservative management was used for 11 (34.4%) patients (Table 1). There were no significant differences between surgical and conservative treatments in terms of patient age, gender, mechanism of injury, neurological status, and extent of anterior defect (P > 0.05). However, we observed that the anterior defect was smaller in patients who received conservative treatment, and all patients with neurological deficits received a surgical approach. For surgical patients, the mean duration of the operation was 168.6 ± 53.3 min, and the mean blood loss was 310.5 ± 316.7 ml. The mean anterior defects were measured as 12.7 ± 9.9 mm preoperatively and 13.6 ± 9.2 mm postoperatively. Although the anterior defect was larger after the operation, there was no statistically significant difference (P > 0.05).

All the patients expressed satisfaction with the outcomes and were able to resume their daily lives independently. The VAS and ODI values obtained at the last follow-up were recorded as 1 (0, 2) and 9 (4, 9) %, respectively, and all patients exhibited successful fracture healing. All four patients with neurological deficits returned to normal at the last follow-up. No significant complications or deaths occurred during the treatment, except for one patient who experienced a delayed neurologic deficit and returned to normal after undergoing emergency spinal canal decompression.

In patients with AS, when a fracture occurs, the spine tends to be displaced into hyperextension, and B3-type fractures are the most common type of thoracolumbar spine fracture[5, 22]. These fractures result in an anterior distraction defect, which increases instability and may impede the healing process[8]. The management of this type of fracture presents a significant challenge for healthcare professionals, whether they are involved in first aid, transportation, or the provision of care and treatment[23]. Additionally, although AS exhibits a strong ability for bone formation, further research is needed to determine whether the anterior distraction defect caused by hyperextension can heal naturally. Therefore, we conducted a retrospective analysis on 32 AS patients diagnosed with type B3 thoracolumbar fractures. The anterior defect was managed without bone graft fusion or active fracture reduction, and successful healing of fractures and positive clinical outcomes were observed in all patients.

The spinal fractures observed in AS patients primarily exhibit instability, affecting all three columns of the spine and often requiring surgical intervention[12, 24, 25]. However, the management of anterior distraction defects has been poorly documented in existing studies. Ye et al.[2] performed percutaneous long-segment fixation and utilized autologous bone block implantation for the anterior defect. Kai et al.[26] utilized hydroxyapatite to fill the disrupted defects in order to achieve support for the anterior column and believed that it is necessary to improve fracture reduction and sagittal alignment for the presence of obvious malalignment. Burke et al.[27] described that gradual reduction using a variable extension-distraction table is a safe and controlled method for achieving anatomical reduction. However, more research suggests that intraoperative reduction is extremely challenging for hyperextension injuries in ankylosed spines[5, 13, 23, 26]. Therefore, Lindtner et al.[5] proposed a new treatment concept in which fracture reduction through postoperative mobilization is deemed feasible, and the individual sagittal profile can be spontaneously restored. The data shows that fracture reduction occurs 3 weeks after surgical fixation using a soft rod, whereas it takes approximately 6 months when more rigid rods are utilized[5]. However, the study did not describe the extent of the anterior defect and whether fracture reduction can be achieved for larger distraction defects. In our study, we measured the range of anterior distraction defects, with more than half of the patients exhibiting an extent of anterior defect exceeding 10 mm, and the largest defect measuring 41.2mm. Consistent with previous studies, we also did not achieve effective reduction during the procedure; instead, the data showed that the procedure actually exacerbated fracture distraction. Although we did not describe data on spontaneous fracture reduction after surgery, the postoperative review shows that some reduction in the anterior distraction defect was achieved (Fig. 1). Additionally, we also discovered that although surgery may worsen fracture distraction, patients with AS can still achieve fracture healing due to their strong bone formation ability (Fig. 2). This not only enhances anterior vertebral height but also partially corrects kyphosis in some patients (Fig. 3).

Nowadays, conservative treatment has gradually been marginalized due to its complications and poor outcomes[28, 29]. However, it remains in use for approximately one third of patients, primarily due to the increased risk of surgical complications[11, 12]. Bäcker et al.[30] believe that non-operative treatment is a feasible approach for patients with fused spines. Chen et al.[31] demonstrated that regardless of the treatment method, there were no significant differences in outcomes, suggesting that nonoperative management should receive more attention for the treatment of ankylosing spinal disorders with spine fractures. In our study, 34.4% of the patients chose conservative treatment. Compared to surgically treated patients, patients who underwent conservative treatment had no neurological damage and a smaller anterior defect, which could also be a reason for choosing conservative treatment. Similar to surgical fixation, the fractures in the conservative treatment group also healed effectively and exhibited restored sagittal alignment at the last follow-up (Fig. 4). Therefore, we believe that conservative treatment should not be overlooked, and further research is necessary to enhance its effectiveness.

For our patients, clinical results were only recorded at the time of the last follow-up visit. Satisfactory outcomes were achieved in all patients. As we all know, complications associated with spinal fractures in patients with AS occur frequently, regardless of the treatment received, especially for elderly patients with pre-existing cardiopulmonary disease[30]. There is even a study that reports a mortality rate of 51% for conservative treatment and 32% for surgical treatment[32]. In our study, one patient who experienced a delayed neurologic deficit and returned to normal after undergoing emergency spinal canal decompression. The remaining patients did not experience any significant complications, and no deaths were recorded during the entire follow-up period. We analyzed the possible reasons for the good curative effect of this study as follows: First, the average age of patients in this study was 58.7 ± 13.1 years old, which was younger than in previous studies. Second, this study only included patients with AS combined with thoracolumbar fractures, excluding cervical fractures with higher complications and mortality rates. Third, with the development of medical technology, clinicians have a more in-depth understanding of AS combined with spinal fractures and can provide better and more reasonable treatment options. Fourth, due to the relatively low incidence of spinal fractures associated with AS, there may be some degree of chance and selection bias contributing to the high reported mortality rate in previous studies.

There were several limitations in our study. Firstly, it was a retrospective study that had the potential for selection bias. Secondly, we only presented the data of the latest follow-up without providing specific time of fracture healing in patients, which may vary depending on the extent of distraction defect. Thirdly, we solely described the bone healing status of patients and did not measure certain parameters before and after fracture healing, such as lordosis angle and anterior vertebral margin height. Despite the limitations in this study, the favorable clinical outcomes suggest that anterior distraction defects may undergo spontaneous healing without active intervention.

Computed tomography

Ankylosing spondylitis

VAS

Visual analogue scale

ODI

Oswestry disability index

ASIA

American Spinal Injury Association

Ethics approval and consent to participate

Ethics committee approval for this article was obtained from the Second Affiliated Hospital of Soochow University, with the number JD-HG-2023-74. Informed consent was obtained from all individual participants included in the study. The whole research process follows the Declaration of Helsinki.

Consent for publication

The patients provided informed consent for the publication of their document imaging, as well as their anonymous and clustered data.

Competing interests

The authors declare that they have no competing interests.

Funding

This work was supported by the National Natural Science Foundation of China (82172425), Jiangsu Provincial Medical Key Discipline (Laboratory) Cultivation Unit (JSDW202223), the Social Development Key Programs of Jiangsu Province-Advanced Clinical Technology (BE2023705), the Key Project of Scientific and Technological Innovation in China's Nuclear Medicine (ZHYLTD2023001), and the cross-translation project for clinical innovation at Suzhou University (ML12301523).

Author Contribution

XZZ contributed to the study conception and design. ZYY, XSZ, FLS, and ZTZ contributed to clinical data collection; JY, JYB, and BCS contributed to radiological data analysis; ZYY and JD contributed to statistical analysis; ZYY, JY, and XSZ contributed to the writing and editing. All authors reviewed the manuscript.

Acknowledgements

None.

Data Availability

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

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You are reading this latest preprint version

Clinical effect of treating hyperextension injuries of the thoracolumbar spine in patients with ankylosing spondylitis, without active intervention on the anterior distraction defect

Status:

Version 1

Abstract

Background

Methods

Results

Conclusion

Figures

Introduction

Materials and methods

Inclusion and exclusion criteria

Follow-up evaluation

Statistical analysis

Results

Discussion

Conclusion

Abbreviations

Declarations

Competing interests

Funding

Author Contribution

Acknowledgements

Data Availability

References

Additional Declarations

Status:

Version 1