Safety and efficacy studies of cross-unilateral, sequential unilateral, and bilateral percutaneous kyphoplasty for double-adjacent thoracolumbar osteoporotic vertebral compression fractures.

Background

Osteoporotic vertebral compression fractures (OVCFs) are a significant cause of morbidity in the elderly population and can lead to severe pain, decreased mobility, and reduced quality of life [ 1 ]. Double-adjacent thoracolumbar (DATL)-OVCFs are a severe form of OVCFs [ 2 ]. Percutaneous kyphoplasty (PKP) under local anesthesia is currently a widely used and effective method for treating DATL-OVCFs, with well-established outcomes [ 3 ]. However, for patients with DATL-OVCFs, PKP presents several challenges [ 4 ]. Some patients experience severe pain and restlessness during surgery, making them unable to cooperate with doctors to complete the operation [ 5 – 7 ].

The traditional bilateral transpedicular approach remains the predominant surgical technique for PKP [ 8 ]. However, it has significant limitations, including prolonged operative time, increased intraoperative blood loss, frequent fluoroscopy utilization, intense intraoperative pain and poor patient tolerance for prolonged positioning, and high local anesthetic consumption [ 8 – 11 ]‌. These drawbacks are particularly pronounced in DATL-OVCFs‌. With surgeons’ increasing proficiency in puncture techniques, the ‌unilateral puncture approach‌ has now entered clinical implementation [ 12 ]. When performing ‌simultaneous unilateral transpedicular punctures ‌of adjacent vertebrae ‌via the same lateral approach‌, puncture instruments are prone to ‌mutual interference and operational conflict [ 2 , 12 , 13 ]‌. Consequently, treatment ‌generally necessitates sequential unilateral puncture procedures‌, which have inherent drawbacks, including ‌prolonged operative time, increased fluoroscopy utilization, intense intraoperative pain, and compromised patient tolerance for prolonged positioning [ 14 ]‌. As a result, minimizing the operative time, reducing intraoperative blood loss, decreasing fluoroscopy utilization, and alleviating intraoperative pain are crucial to avoid complications in elderly patients and ensure the successful completion of surgery [ 15 , 16 ]. The cross-unilateral puncture approach has distinct advantages and allows access to both the left and right vertebral pedicles without instrument interference between the two sides [ 12 ]. This may lead to reduced operative time, blood loss, intraoperative fluoroscopy, and intraoperative pain. However, to date, there have been no comparative studies on cross-unilateral (CU), sequential unilateral (SU), and bilateral (BI) PKP for DATL-OVCFs.

This study aimed to compare the clinical efficacy and safety of CU versus SU or BI PKP for the treatment of DATL-OVCFs.

Methods

Study design and population

The clinical study proposal was approved by the Medical Ethics Committee of the authors’ institute (Approval number: YJ2020006). From June 2019 to June 2024, 182 consecutive patients with DATL-OVCFs who underwent PKP were included in this study. The patients were divided into three groups according to the surgical approach: CU ( n = 42), SU ( n = 76), and BI ( n = 64) groups. All patients provided written informed consent before the procedures. The clinical characteristics of the 182 patients are summarized in Table 1 .

Inclusion criteria were as follows: (1) elderly (≥ 60 years); (2) thoracolumbar (T10–L5) double adjacent fresh OVCFs (type A1 according to AOSpine thoracolumbar spine injury classification system) [ 17 ]; (3) minor injury or no history of trauma without neurological deficit; (4) persistent pain and fatigue in thoracolumbar vertebrae significantly affecting daily life; (5) diagnosis of osteoporosis with a T value of bone density test less than − 2.5 using dual-energy X-ray absorptiometry (DXA).

The exclusion criteria were as follows: (1) neurological deficits; (2) polytrauma; (3) preexisting spinal deformity or previous spinal surgery; (4) clinical or imaging evidence of metastatic bone tumor or multiple myeloma; (5) asymptomatic fractures; (6) systemic or local infections or severe bleeding disorders.

Preoperatively, standard clinical examinations and evaluations, including medical history, physical examination for percussion pain, assessment of pain intensity using the visual analog scale (VAS), and activity level using the Oswestry Disability Index (ODI), were performed. X-rays of the relevant spinal region in two planes, computed tomography, magnetic resonance imaging (T1-weighted and T2-weighted sequences, including short tau inversion recovery sequences), and bone density measurement using DXA were performed.

All patients underwent surgery within 3 days of admission to relieve pain, restore vertebral body height, and collect segmental kyphosis data. All patients received calcium (1000 mg of elemental calcium daily), vitamin D (600 IU/day), and alendronate (70 mg/week).

Surgical procedure

Six independent and experienced spine surgeons performed surgeries. All surgical procedures were performed under local anesthesia. The patients were placed in the prone position on four bolsters on a radiolucent operating table, with the abdomen freely suspended. A manual lordotic maneuver was then performed to correct the kyphosis.

In the CU group, simultaneous surgery was performed at both vertebral levels. Two 1-cm skin incisions were made percutaneously lateral to the desired entry point of the pedicle at the proximal vertebra and the contralateral pedicle at the distal vertebra. A trocar (Shandong Guanlong Medical Utensils Co., Ltd., Jinan City, Shandong Province, China) with a cannula was inserted into the pedicle at the fractured vertebra using a unipedicular approach as a working channel. After removing the trocar, a balloon was placed in the working channel and slowly inflated to create a low-pressure cavity for cement injection. Inflation continued until the balloon pressure reached 300 psi. The balloon was then deflated and removed, and Polymethylmethacrylate (PMMA) cement was injected into the defect of the fractured body through the cannula under continuous fluoroscopic monitoring. PMMA insertion was considered complete when it reached the posterior third of the vertebral body or showed a potential tendency for cortical, epidural, or anterior venous cement leakage (Fig. 1 ). In the SU and BI groups, after unilateral and bilateral transpedicular PKP were completed on the proximal vertebra, another unilateral and bilateral transpedicular PKP was performed on the distal vertebra.

Neurological examination was performed soon after the operation. The patients were encouraged to walk while wearing a three-point fixation brace after surgery. Anteroposterior and lateral radiographs were obtained to evaluate fracture reduction and deformity correction.

The operative time, intraoperative fluoroscopy time, estimated blood loss, PMMA volume, intraoperative back pain VAS score, and complications such as bone cement leakage, adjacent segment fracture, cerebrospinal fluid leakage, and infection were noted. Investigator satisfaction scores (ISS), patients’ anesthesia satisfaction scores (PASS), and anesthesia re-administration intention rates (ARIR) were also recorded. Details were presented in our previous study [ 18 ]. Back pain intensity was assessed using VAS (0 = no pain, 10 = worst pain). Functional outcomes were measured using ODI. Vertebral kyphosis was measured between the superior and inferior endplates of the fractured vertebra. Anterior vertebral body height (AVBH) of the fractured vertebra was measured using lateral radiography. Two independent, blinded spine surgeons completed the clinical evaluation of the patients. In addition, three independent, blinded spine surgeons assessed the radiographs. Clinical and radiological results were calculated preoperatively, postoperatively, and at the final follow-up.

Statistical analysis

Statistical analyses were performed using SPSS 18.0 (SPSS Inc., Chicago, IL, USA). Continuous variables were expressed as mean ± standard deviation. Independent variables, including age, body mass index (BMI), T-score, injury time, operative time, fluoroscopy time, blood loss, intraoperative back pain VAS score, hospital stay, cost, injected cement volume, ISS, and PASS, were compared among the three groups using one-way analysis of variance (ANOVA). Differences in sex, distribution of fractured vertebrae, cement leakage, and ARIR among the three groups were compared using the chi-square test. A three-way repeated-measures ANOVA was used to compare VAS, ODI, AVBH, and Cobb angle among the three groups. Two-sided p-values < 0.05 were considered statistically significant.

Results

The baseline characteristics and comparative analyses of the three groups are summarized in Table 1 . No significant differences in age, sex, causes and distribution of fractures, injury time, T-score, or BMI were observed among the groups. All patients had similar baseline characteristics, allowing a fair comparison of surgical outcomes. The CU group had significantly shorter operative times than the SU and BI groups (20.76 ± 3.76 vs. 38.76 ± 5.55 and 57.52 ± 8.60 min, respectively; p < 0.001). Blood loss was significantly lower in the CU and SU groups than in the BI group (7.12 ± 2.13 and 6.68 ± 1.92 vs. 14.34 ± 3.83 mL; p < 0.001). The CU group also had the lowest intraoperative fluoroscopy time (20.31 ± 3.34 vs. 31.34 ± 2.63 and 41.50 ± 3.59 min; p < 0.001). Intraoperative pain was significantly lower in the CU group than in the SU and BI groups (1.83 ± 0.88 vs. 2.84 ± 0.82 and 3.45 ± 1.14 min; p < 0.001). Details are presented in Table 2 .

Clinical outcomes

Most patients in all three groups experienced excellent pain relief and improved physical ability. In the CU group, VAS scores decreased from 6.36 ± 1.10 preoperatively to 1.81 ± 0.86 postoperatively ( p < 0.05); in the SU group, from 6.38 ± 1.06 to 1.97 ± 0.82 ( p < 0.05); and in the BI group, from 6.31 ± 1.23 to 2.17 ± 0.83 ( p < 0.05). Similarly, ODI scores decreased from 62.33 ± 11.33 preoperatively to 20.31 ± 9.79 postoperatively in the CU group ( p < 0.05), from 67.71 ± 12.64 to 21.03 ± 9.89 in the SU group ( p < 0.05), and from 59.95 ± 14.22 to 22.67 ± 9.81 in the BI group ( p < 0.05). VAS and ODI scores did not differ significantly among the three groups, either postoperatively or at the 1-year follow-up ( p > 0.05). Details are presented in Table 3 .The ISS and PASS were significantly higher in the CU group than in the SU and BI groups (2.50 ± 0.63 vs. 2.07 ± 0.75 and 1.50 ± 0.85, P < 0.05; 4.00 ± 0.66 vs. 3.34 ± 1.08 and 2.64 ± 1.35, P < 0.05). Thirty-seven patients in the CU group (88.09%) versus 58 patients in the SU group (76.32%) and 33 patientsin the BI group (54.56%) would choose their anesthesia method again ( P < 0.05). Details are presented in Table 2 .

Radiological outcomes

In the CU group, AVBH improved from 17.64 ± 5.88 preoperatively to 21.33 ± 5.72 postoperatively; in the SU group, from 17.73 ± 6.03 to 21.38 ± 5.94; and in the BI group, from 16.97 ± 5.72 to 20.65 ± 5.59. However, no significant differences were observed among the groups at the 1-year follow-up ( p > 0.05). Kyphotic deformity was significantly reduced postoperatively in all groups. Local kyphosis decreased from 21.13 ± 5.50 preoperatively to 18.13 ± 5.81 postoperatively in the CU group, from 21.09 ± 4.93 to 18.02 ± 5.24 in the SU group, and from 21.62 ± 5.18 to 18.55 ± 5.08 in the BI group, with no significant differences at the 1-year follow-up ( p > 0.05). Radiographic results are presented in Table 4 .

Complications

Leakage of bone cement outside the vertebral body was observed in all groups on the postoperative anteroposterior and lateral radiographs. The bone cement leakage rates were 11.9% (5 of 42) in the CU group (3 in the disc, 1 in the vertebral vein, and 1 in the paravertebral vein); 17.1% (13 of 76) in the SU group (7 in the disc, 4 in the vertebral vein, and 2 in the paravertebral vein); and 10.9% (7 of 64) in the BI group (4 in the disc, 2 in the vertebral vein, and 1 in the paravertebral vein), with no significant differences among the groups ( p > 0.05). The adjacent segment fracture rates were 4.76% (2 of 42) in the CU group; 6.58% (5 of 76) in the SU group and 4.69% (3 of 64) in the BI group, with no significant differences among the groups ( p > 0.05) (Table 2 ). None of the leakages required special treatment, and no clinical symptoms were attributed to cement leakage. Moreover, no other major postoperative complications such as neurological damage, hemorrhage, infection, or pulmonary embolism were observed.

Discussion

This study provides valuable insights into the safety and efficacy of three PKP approaches for treating DATL-OVCFs. Our findings suggest that the CU approach offers significant advantages over the SU and BI techniques by reducing operative time, blood loss, intraoperative fluoroscopy time, and intraoperative pain. These advantages are crucial for minimizing surgical invasiveness and improving patient outcomes, particularly among elderly patients at increased risk of cardiovascular and cerebrovascular complications. Our study aligns with previous research that has demonstrated the advantages of unilateral puncture over bilateral puncture in reducing operative time, blood loss, and fluoroscopy use [ 12 , 13 , 15 ]. Additionally, CU puncture has been shown to offer advantages over SU puncture in reducing both operative time and fluoroscopy exposure [ 12 ]. However, previous studies have not addressed the evaluation of intraoperative pain. Our study, therefore, provides novel insights by suggesting that CU PKP may also reduce intraoperative pain, an aspect not previously explored in the literature. This finding offers a new perspective on optimizing surgical procedures for improved patient comfort, and further research is warranted to validate its clinical significance.

The ability of the CU technique to reduce operative time, blood loss, fluoroscopy time, and intraoperative pain can be attributed to several factors. First, its ability to access unilateral and simultaneous cross injections is a key factor contributing to its efficiency. Unlike the SU technique, which requires two sequential punctures and cement injections, or the BI technique, which involves independent punctures and cement injections on each side, CU enables simultaneous augmentation of two adjacent vertebral bodies without repeated puncture and repositioning. This approach reduces the overall duration of the procedure, shortens fluoroscopy time, and limits radiation exposure to both the surgical team and patient. Given the cumulative occupational radiation risk faced by spine surgeons performing high-volume percutaneous procedures, the reduction in fluoroscopy time provided by CU has important implications for long-term professional health [ 10 , 11 , 19 ].

Second, the decrease in intraoperative blood loss observed with CU can be explained by reduced tissue trauma and vascular injury associated with fewer puncture tracts. Patients with OVCF are often elderly and may have impaired coagulation function or comorbidities that increase the risk of perioperative complications. Therefore, minimizing blood loss is clinically meaningful and may promote faster recovery and lower complication rates. Moreover, because CU allows simultaneous treatment of both sides of the vertebra, there is no need for patient repositioning or prolonged prone positioning between punctures. This technique not only streamlines the workflow but also reduces anesthesia time, perioperative hemodynamic fluctuations, and the risk of cardiopulmonary compromise, which can be a concern in frail elderly patients [ 19 , 20 ].

Third, CU appears to result in lower intraoperative pain compared with the BI and SU approaches. Multiple puncture sites required in SU and BI are associated with greater soft tissue trauma and longer operative times, leading to greater nociceptive stimulation. In contrast, CU requires only a single skin entry point at each vertebra and shortens operative time, thereby minimizing local tissue irritation and decreasing pain perception during the procedure. This advantage is particularly relevant in cases performed under local anesthesia, where patient cooperation is necessary and excessive pain may compromise surgical accuracy. Reduced pain may also improve patient satisfaction and willingness to undergo similar procedures if needed in the future [ 7 ].

Although the CU technique demonstrated clear advantages in operation efficiency, blood loss, and intraoperative pain, the clinical and radiological outcomes across the three groups were largely similar. Specifically, postoperative improvements in VAS and ODI scores, vertebral body height restoration, and local kyphotic correction were comparable across all groups, with no significant differences at either the immediate or 1-year follow-up. These results suggest that all three techniques, despite their differences in surgical approaches, achieve similar long-term clinical and radiological outcomes in treating DATL-OVCFs. This finding is consistent with previous studies comparing various PKP techniques [ 8 , 11 , 19 – 22 ].

Furthermore, cement leakage and adjacent segment fracture rates were comparable among the three groups, reinforcing the safety profiles of all three techniques. The similarly low leakage and adjacent segment fracture rates across the groups suggest that, regardless of the approach, PKP remains a safe and effective treatment for DATL-OVCFs, with minimal risk of complications associated with cement extravasation.

This study has certain limitations. It was a retrospective study, with all the inherent biases. The results were available from a single center, small patient population and the short follow-up study. A further limitation of this study seemed to be non-randomly. Future studies, a prospective randomized controlled study enrolling more patients through long-term followup period are needed to compare CU with with SU and BI PKP for DATL-OVCFs more reliably and objectively.

In summary, for DATL-OVCFs, CU PKP is a minimally invasive and safe technique that offers advantages such as reduced blood loss, shorter operative time, less intraoperative fluoroscopy, and lower intraoperative pain compared with SU and BI PKP, without compromising long-term clinical or radiological outcomes. This aligns with the current trend toward enhancing perioperative safety, optimizing patient experience, and reducing healthcare costs.

Acknowledgements

Not applicable.

Abbreviations

Percutaneous Kyphoplasty

Double-Adjacent Thoracolumbar Osteoporotic Vertebral Compression Fractures

Cross-Unilateral

Sequential Unilateral

Bilateral

Visual Analogue Scale

Oswestry Disability Index

Dual-energy X-ray Absorptiometry

Polymethylmethacrylate

Investigator Satisfaction Scores

Patients’ Anesthesia Satisfaction Scores

Anesthesia Re-administration Intention Rates

Anterior Vertebral Body Height

Analysis of Variance

Author contributions

XL and SQH designed the study. SQH, YFQ, and KL collected the data. SQH and CXT were involved in the manuscript writing, literature search, data interpretation, and data monitoring. YML and XL were responsible for the data collection and analysis. All authors read and approved the final manuscript.

Funding

This work was supported by the Zhejiang Provincial Medical and Health Research Fund (2022KY351) and the Wenzhou Science and Technology Project (YC20250119). None of the authors had professional or financial affiliations that could potentially bias this study.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

The clinical study proposal was approved by the Medical Ethics Committee of the authors’ institute(Approval number: YJ2020006).

Consent for publication

We have obtained consent to publish from the participants.

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Associated Data

Data Availability Statement

No datasets were generated or analysed during the current study.