Comparison between short-segment versus long-segment screw fixation in osteopenic and osteoporotic vertebral compression fractures in thoracolumbar junction with myelopathy

doi:10.21203/rs.3.rs-5306424/v1

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Comparison between short-segment versus long-segment screw fixation in osteopenic and osteoporotic vertebral compression fractures in thoracolumbar junction with myelopathy

https://doi.org/10.21203/rs.3.rs-5306424/v1

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Purpose Osteopenic and osteoporotic vertebral compression fracture (OVCF) is a prevalent clinical problem, particularly in the elderly. Management of this condition often requires surgical intervention involving screw fixation of vertebral bodies. However, the optimal extent of screw fixation remains a topic of debate among neurosurgeons. This retrospective study compared the clinical outcomes, radiographic results, and complication rates between short-segment and long-segment screw fixation in patients with OVCF at the thoracolumbar junction (TLJ) and with myelopathic symptoms due to a spinal cord-compressing lesion.

Methods A total of 48 patients with OVCFs at the TLJ and myelopathic symptoms and who underwent either short-segment (two-level) or long-segment (>2 levels) screw fixation were studied. Clinical outcomes comprised Visual Analog Scale (VAS)score, Eastern Cooperative Oncology Group (ECOG) performance status, Frankel scale, and modified Japanese Orthopedic Association score.

Results Both groups showed postoperative improvement in VAS scores, with no significant difference. However, postoperative improvement in Frankel scale (p=0.01) and ECOG performance status (p<0.01) was significantly greater in the short-segment versus long-segment fixation group. Conversely, long-segment fixation produced superior preservation of the postoperative correction angle (p=0.02). There were no significant differences in overall complication rates, including mechanical failure, between the two groups.

Conclusion Short-segment screw fixation provides comparable clinical outcomes to long-segment fixation in the management of OVCFs with myelopathic symptoms. It is also noteworthy that short-segment screw fixation is not predisposed to instrument failure. These findings suggest that short-segment screw fixation may be a viable option for many patients with OVCFs, depending on clinical condition.

Complication rates

Long-segment

Myelopathy

Osteoporotic vertebral compression fracture

Screw fixation

Short-segment

Osteopenic and Osteoporotic vertebral compression fractures (OVCFs) present significant clinical difficulties, particularly in the elderly, in which such fractures are prevalent [1,2]. Moreover, vertebral compression fractures represent the most prevalent complication of spinal osteoporosis, and surgical intervention for OVCFs may pose several challenges [3]. OVCFs can result in localized pain at the fracture site, and loss of vertebral body height, and may subsequently contribute to the development of kyphosis and myelopathy [4]. Several management strategies are available, with surgical intervention involving screw fixation of vertebral bodies frequently employed to address instability and alleviate associated myelopathy. Due to its high fusion rate, durable axial loading, and safe procedure, posterior lumbar interbody fusion with posterior screw fixation is widely employed in lumbar spinal lesions in which decompressive laminectomy and bone fusion are mandatory [5]. Although surgical interventions for OVCFs are widely accepted, there are no established guidelines as to surgical approaches, fusion levels, or the extent of kyphosis correction [6].

The debate centers on the comparison between short-segment and long-segment screw fixation techniques. Both approaches aim to restore vertebral alignment, provide stability, and alleviate clinical symptoms. Thoracolumbar junction fractures were conventionally treated with long constructs with four screws proximal and distal to the fracture level. Long-segment fixation imparts greater stability and support with less chance of implant failure than short-segment fixation does, but at the cost of sacrificing motion segments [7]. To overcome the limitations of long-segment fixation, many authors suggested a short-segment fixation technique, incorporating the pedicles of fractured vertebrae, well over a decade ago [8]. Yet, clarification of the superiority of one method over the other remains elusive, prompting the need for further comparative analysis [9].

By conducting a retrospective study in 48 patients with OVCFs who underwent either short-segment or long-segment screw fixation, we aimed to address the differences between the two methods in clinical outcomes, radiographic results, and complication rates.

Patient selection

All patients diagnosed with osteopenia or osteoporosis showing one or more compression fractures of vertebral bodies at the thoracolumbar junction (T10–L2) and who underwent screw fixation, including at the fracture level, at a single institution from January 2012 to December 2023, were screened. As established by the World Health Organization (WHO), osteopenia is defined as T-score on dual-energy x-ray absorptiometry (DXA) bone scan between − 1 to -2.5, while values less than − 2.5 are defined as osteoporosis. From the screened cohort, patients with osteopenia or osteoporosis showing vertebral compression fracture and myelopathic symptoms were included. Overall, a total of 48 patients were enrolled, after applying the following exclusion criteria: <5 months of postoperative follow-up; incomplete medical or radiographic records; or normal bone density on bone densitometry.

Group classification

The short-segment fixation group was defined as patients with fixation of two vertebral levels and in whom pedicle screws were placed one level above and below, and at the index level of the OVCF. The long-segment fixation group was defined as patients with any fixation procedure involving more vertebral levels than the short-segment fixation group.

Surgical indication and technique

All patients in the study had an OVCF at the thoracolumbar junction and myelopathic symptoms that correlated with the affected spinal level. All surgeries were conducted by one of three board-certified spinal neurosurgeons, or one board-certified orthopedic spine surgeon.

Short-segment fixation

Patients undergoing short-segment fixation were positioned prone on a Jackson spinal table and placed under general anesthesia. A midline skin incision was made, extending one level above and below the targeted vertebra. Using a navigation system, pedicle screws 5.5–7.5 mm in diameter, based on pedicle size, were inserted into the pedicles one level above and below the targeted vertebra using the Solera® system (Medtronic Sofamor Danek USA, Inc.; Memphis, TN, USA). At the targeted vertebra, unilateral pedicle screws were placed. The decision regarding the side for pedicle screw insertion was based on computed tomography (CT) findings of pedicle osteolysis, and lateral tumor extent determined by magnetic resonance imaging (MRI). Temporary rods were applied to one side. Subsequently, unilateral laminectomy and pediculectomy were performed to decompress the spinal cord. The unilateral pediculectomy provided adequate access to the ventral aspect of the spinal canal and vertebral body, allowing removal of the osteolytic vertebral body associated with the metastatic tumor, using an osteotome and reverse-angled curette. Following tumor excision and confirmation of ventral decompression of the spinal cord, the anterior column was reinforced with the insertion of 15 mL of allograft bone chips and a titanium cage. Posterolateral fusion was carried out on the remaining unilateral laminae using 15 mL of allograft bone chips. Intraoperative plain radiographs and postoperative CT scans confirmed accurate screw placement.

Long-segment fixation

For long-segment fixation, patients were positioned prone on a Jackson spinal table and administered general anesthesia. A midline skin incision was made extending two levels above and below the area of tumor invasion. Subperiosteal dissection was carried out to expose the spinous processes and laminae. Following laminectomy and/or facetectomy, the epidural tumor was circumferentially excised from the spinal cord to facilitate separation surgery. Pedicle screws were inserted at the vertebrae adjacent to the targeted vertebra, bypassing the index vertebra. Bilateral posterolateral fusion was then performed on the remaining facet joints and/or transverse processes. Intraoperative plain radiographs were subsequently obtained to confirm accurate screw placement.

Radiographic assessments

All radiographic parameters were measured on x-ray films to assess the degree of vertebral alignment restoration and maintenance. Local kyphosis angle (LKA) was defined as the angle formed by the superior endplate of the upper vertebra and the inferior endplate of the lower vertebra. A representative measurement of LKA is demonstrated in Fig. 1. Correction angle was defined as the difference between preoperative LKA and immediate postoperative LKA. Loss of correction angle was defined as the difference between immediate postoperative LKA and LKA at the latest follow-up.

Figure 1. An illustration of LKA measurement

A representative case of compression fracture of L1. The angle formed between the two hypothetical perpendicular lines of the superior endplate of the upper vertebra and the inferior endplate of the lower vertebra is measured and defined as LKA.

LKA: Local kyphosis angle

Screw angle change (SAC) was defined as an alteration > 10° in the angle between the pedicle screw and the inferior endplate when comparing immediate postoperative lateral lumbar x-rays with those obtained at the most recent follow-up. Cases of screw pull-out were identified by noticeable changes in the position of the screw or screw head between immediate postoperative lateral lumbar x-rays and the most recent follow-up images.

Clinical assessments

Clinical outcomes were evaluated using various modalities, including Visual Analog Scale (VAS) scores for pain assessment, Eastern Cooperative Oncology Group (ECOG) performance status, the Frankel scale for evaluation of neurologic function, and modified Japanese Orthopedic Association (mJOA) scores for functional assessment. Each clinical parameter was compared preoperatively and at the last follow-up ≥ 5 months postoperatively: the differences in each parameter were termed as ΔVAS, ΔECOG, ΔFrankel, and ΔmJOA.

Statistical analyses

All patients were retrospectively reviewed based on their medical and radiographic records. Statistical analyses were performed using SPSS version 29.0 (IBM Corp.; Armonk, NY, USA). Mean values for the two groups were compared using the Student's t-test. The Chi-squared test was used to analyze proportional differences between the two groups. A p-value < 0.05 indicated statistical significance.

Patient demographics

A total of 48 patients were included: 17 in the short-segment group (8 males, 9 females) and 31 in the long-segment group (6 males, 25 females). Demographic data for the two groups are shown in Table 1. The female prevalence in the long-segment group was statistically significant (p = 0.04). Mean age was 75.8 years for the short-segment group and 70.7 years for the long-segment group (p = 0.88). In the short-segment group, 15 patients showed OVCF after slip down, while two patients had an unclear history of trauma before presenting with OVCF. The long-segment group included 26 slip-down cases, one fall, two traffic accidents, and two patients with an unclear history of trauma. The short-segment group included one T10, one T11, eight T12, six L1, and one L2 index-level OVCFs, while the long-segment group included three T11, eleven T12, thirteen L1, and four L2 index-level OVCFs. The mean(± standard deviation) postoperative follow-up duration was 21.4 ± 4.6 months for the short-segment group and 30.3 ± 4.6 months for the long-segment group (p = 0.13).

Table 1

Patient Demographics
		Short segment group	Long segment group	p-value
Number of patients		17	31
Sex	Male	8(47%)	6(19%)	0.04^*
	Female	9(53%)	25(81%)
Mean Age		72.9 ± 16.4	71.4 ± 11.6	0.32
Mean number of levels fused		2	4.5
Cause of fracture	Slip down	18	30
	Fall down	0	1
	Traffic accident	1	2
	Unclear	2	2
Index level	T10	1(4.8%)	0
	T11	1(4.8%)	3(8.6%)
	T12	8(38.1%)	11(31.4%)
	L1	6(28.6%)	13(37.1%)
	L2	1(4.8%)	4(11.4%)
Mean F/U Duration(months)		21.4 ± 4.6	30.3 ± 4.6	0.13
Preoperative Use of Osteoporotic Medication
	Anabolic agents	8	11
	Antiresorptive agents	1	8
	None	8	12

^*Indicates statistical significance (p < 0.05).

Clinical assessments

As shown in Table 2, the mean operation time was 276 minutes in the short-segment group and 413 minutes in the long-segment group (p = 0.03). Corresponding values for postoperative hospital stay were 7.2 days and 9.0 days (p = 0.01). The changes from preoperative to postoperative VAS scores were − 5.7 and − 5.6 in the short-segment and long-segment groups, respectively (p = 0.17). The differences between preoperative and postoperative Frankel scale scores were 1.2 and 0.9 in the short-segment and long-segment groups, respectively (p = 0.01). Corresponding differences for ECOG performance status were − 1.0 and − 0.5 (p = 0.00). The changes from preoperative to postoperative mJOA scores were 2.2 and 1.9 in the short-segment and long-segment groups, respectively (p = 0.51). No complications related to wound infection or dehiscence were found. One patient in the short-segment group underwent revision surgery due to postoperative neurologic deterioration, whereas no cases of revision surgery were observed in the long-segment group (p = 0.17)

Table 2

Clinical Parameters
		Short segment group	Long segment group	p-value
Operation Time (min)		281 ± 33	406 ± 32	0.03^*
Hospital stay (days)		7.9 ± 1.4	19.6 ± 0.6	0.01^*
Clinical outcome	ΔVAS	-5.3	-5.4	0.17
	Δfrankel	1.3	0.9	0.01^*
	ΔECOG	-1	-1.2	0.00^*
	ΔmJOA	2.2	1.9	0.51

^*Indicates statistical significance (p < 0.05).

^aIndicates revision surgeries due to neurological deterioration along with radiographic findings.

Radiographic assessments

The radiographic parameters were compared between the two groups as shown in Table 3. The mean (± standard deviation) correction angle was − 6.2° in the short-segment group and − 10.6° in the long-segment group (p = 0.35). The mean loss of correction angle was 7.5° and 2.2° in the short-segment and long-segment groups, respectively (p = 0.02). SAC was observed in three patients in the short-segment group and six patients in the long-segment group (p = 0.89). Representative cases of SAC in the short-segment and long-segment groups are shown in Figs. 2 and 3, respectively. Two pull-out cases were found in the short-segment group, while three pull-out cases were found in the long-segment group (p = 0.82). Representative cases of pull-out in the short-segment and long-segment groups are shown in Figs. 4 and 5, respectively.

Table 3

Radiographic Parameters
		Short segment group	Long segment group	p-value
Mean Correction Angle		-6.2 ± 2.1	-10.6 ± 1.3	0.35
Mean Loss of Correction Angle		7.5 ± 2.3	2.2 ± 1.1	0.02^*
Mechanical Failure	Screw angle change	3(14.3%)	6(19.4%)	0.89
	Pull-out	2(9.5%)	3(9.7%)	0.82

^*Indicates statistical significance (p < 0.05).

This retrospective study was designed to weigh the pros and cons of short-segment versus long-segment fusion in patients with OVCFs at the thoracolumbar junction and myelopathic symptoms. Pain-relieving efficacy, complication rates (including mechanical failures), and initial correction angles were not significantly different between the two groups. However, improvements in neurologic assessments and ECOG performance status showed statistically significant superiority in the short-segment group. Operation time and postoperative hospital stay also showed statistically significant superiority in the short-segment group, which may endorse short-segment fixation in OVCF at the thoracolumbar junction as a cost-efficient and risk-avoiding technique. Conversely, long-segment fusion demonstrated a smaller loss of correction angle, meaning that the technique is superior in preserving the intended postoperative sagittal angles.

In patients with OVCF at the thoracolumbar junction and myelopathic symptoms, surgical treatment can restore vertebral body height, correct angular deformity, decompress neural tissue, and facilitate rapid mobilization and rehabilitation [10]. However, contention remains about the extent of fixation in such patients. Short-segment fusion offers benefits such as reduced invasiveness, making such fusion more suitable for elderly patients, and preserving a greater number of motion segments. Conversely, short-segment fusion raises concerns about the potential for increased mechanical load on the constructs, which may result in early implant failure and the loss of sagittal alignment [11]. Peters et al. showed, in thoracolumbar vertebral fracture, that a two-level above and below fusion technique provided more stability than a one-level above and below fusion technique [12]. Altay et al. demonstrated that short-segment and long-segment fixation yielded comparable clinical outcomes; however, sagittal radiographic parameters were superior with long-segment fixation [13]. Tezeren and Kuru reported a high failure rate with short-segment fixation, whereas long-segment fixation was associated with an extended operative time and a significant increase in blood loss [14]. Conversely, Jeong et al. concluded that short-segment fixation including the fractured vertebra in thoracolumbar and lumbar burst fractures demonstrated comparable clinical and radiologic results than those of long-segment fixation [15].

Although consensus is lacking on the extent of fusion in patients with OVCF at the thoracolumbar junction, this study contributes to the debate by demonstrating that clinical outcomes such as VAS and mJOA scores, mechanical failure rates, and initial correction angles were not significantly different between the two groups. However, the short-segment group demonstrated statistically significant superiority in neurologic improvements and ECOG performance status. Additionally, both operation time and postoperative hospital stay were significantly shorter in the short-segment group.

The findings of this study indicate that both short-segment and long-segment fixation demonstrate significant improvements in postoperative VAS scores, with comparable outcomes between the two groups. However, nuanced differences emerge upon closer examination, particularly regarding improvements in neurologic function and the radiographic preservation of correction angle. Notably, short-segment fixation exhibits significant advantages in certain aspects, such as postoperative improvements in Frankel score and ECOG performance status, while long-segment fixation demonstrates superior preservation of postoperative correction angle.

Limitations

This study has a few limitations. Patient data were pooled from four different operators from a single institution; therefore, the surgical techniques used in each operation may have been heterogenous. Further, the surgical indication for patients with OVCF at the thoracolumbar junction and myelopathic symptoms depended largely on the policy of each surgeon, which might have resulted in selection bias of operative patients. The retrospective design and stringent exclusion criteria of the study present a notable limitation, as such factors may have constrained the sample size to a relatively small number.

This comparative study seeks to contribute to the ongoing debate surrounding the optimal management of OVCFs. While both short-segment and long-segment screw fixation techniques offer viable options, our findings suggest that short-segment fixation may be particularly advantageous in certain clinical scenarios, offering comparable clinical outcomes while mitigating the risk of instrument failure.

Conflict of interest

The authors declare no competing interests.

Ethics declarations

Ethical approval

An institutional review board exemption was obtained for the retrospective review of clinical information obtained herein, including imaging studies.

Consent to participate

No written patient consent was obtained for this retrospective survey. The retrospective review of medical records and radiographs received the approval of our institutional review board.

Funding

Not applicable.

Author Contribution

J.P. and C.N. designed the study and reviewed the manuscript. C.N. collected all data and wrote the main manuscript.

Acknowledgement

None

Data availability

The data of this study are available from the corresponding author, upon reasonable request.

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No competing interests reported.

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Comparison between short-segment versus long-segment screw fixation in osteopenic and osteoporotic vertebral compression fractures in thoracolumbar junction with myelopathy

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Version 1

Abstract

Figures

Introduction

Methods

Patient selection

Group classification

Surgical indication and technique

Short-segment fixation

Long-segment fixation

Radiographic assessments

LKA: Local kyphosis angle

Clinical assessments

Statistical analyses

Results

Patient demographics

Clinical assessments

Radiographic assessments

Discussion

Limitations

Conclusion

Declarations

Ethics declarations

Funding

Author Contribution

Acknowledgement

Data availability

References

Additional Declarations

Status:

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