This study was a prospective randomized controlled trial (approved by the Ethics Committee of the First People’s Hospital of Zigong), and the study subjects were patients admitted to the Department of Orthopedics of the First People’s Hospital of Zigong from January 2021 to January 2023.

Inclusion criteria:

Diagnosis of acute single-segment OVCFs by imaging (X-ray, CT, MRI, or bone scan if contraindicated).

Exclusion criteria:

• Multi-segmental OVCFs.

A single-blind randomization scheme was used to group patients based on computer-generated random numbers. An independent third party grouped patients with eligible OVCFs in either the PCKP group (67 patients) or the unilateral percutaneous kyphoplasty (UPKP) group (72 patients). The baseline characteristics of patients in the two groups, including vertebral compression severity (using the Genant semi-quantitative grading, defined as mild for Genant grades 0–1, moderate for grade 2, and severe for grade 3), were balanced and comparable.

All surgeries were performed by experienced spine surgeons from the same surgical team who are skilled in vertebral body strengthening techniques.

Surgical instruments and materials: PCKP and UPKP surgical instrument systems were provided by Shanghai Kellett Medical Technology Co. Bone cements were all made of polymethylmethacrylate (PMMA) produced by Mendec Spine Resin, Italy.

A total of 197 patients with single-segment OVCFs were initially enrolled in this study, and after screening with strict inclusion and exclusion criteria, 171 patients met the conditions, 27 were lost during data follow-up, and 5 were withdrawn from the study due to death, resulting in a complete collection of data from 139 patients with acute single-segment thoracolumbar OVCFs, including 55 male and 84 female individuals. All of them were low- or no-energy-caused injuries, and the distribution of fractured vertebrae was as follows: 5 cases of T6, 7 cases of T7, 9 cases of T8, 9 cases of T9, 12 cases of T10, 14 cases of T11, 19 cases of T12, 21 cases of L1, 16 cases of L2, 11 cases of L3, 9 cases of L4, and 7 cases of L5, of which the thoracolumbar combined segment (T10–L2) accounted for 58.99% (82/139).

In the present study, we demonstrated that PCKP exhibited a significant advantage in terms of early efficacy, manifesting as rapid pain relief at 2 days postoperatively. This was evidenced by a 42.65% improvement in the VAS score compared with UPKP and a 23.38% improvement in the ODI index compared with UPKP. Lv et al. (2023) observed a positive correlation between early pain relief after vertebroplasty and symmetrical bone cement distribution. This observation underscores the significance of adequate bone cement distribution and filling in determining the efficacy of vertebroplasty treatment. A comparative analysis of the baseline data from the two patient groups included in this study, operated on by the same surgeon, revealed no statistically significant differences (p > 0.5). However, the superiority of PCKP in terms of pain management appears to be associated with its capacity to achieve adequate cement filling within the vertebral body using a curved bone drill, thereby implementing the “stress rebalance theory.” First, PCKP creates a continuous stress gradient by loosening the dense trabeculae through the curved bone drill, thus overcoming the mechanical limitations of the traditional linear puncture path of UPKP. Second, the Kummel-like cavity generated by the curved balloon expansion of PCKP has a synergistic effect on the hydrodynamic characteristics of the cement under low-pressure perfusion, which can significantly reduce the resistance to cement injection and achieve synergy between low-pressure perfusion and the microarchitecture of cancellous bone, effectively circumventing the “rebalancing theory” of UPKP. This matching approach significantly reduces resistance to cement injection, achieving a high bone cement filling rate (91.04% vs. 76.39%) and a more satisfactory of early pain relief effect. Furthermore, Sun Y. et al. (2024) observed that when the intravertebral cement filling rate ranged from 0.4 to 0.6, a favorable equilibrium was attained between the mitigation of complications and the promotion of favorable treatment outcomes. This finding is further supported by the significant early pain relief observed, which suggests that the uniform distribution of bone cement can more effectively create microfractures in the vertebral body, achieve anatomical–mechanical two-dimensional reconstruction, optimize the vertebral load transfer path, and thus reduce local stress concentration to achieve biomechanical stabilization, which results in better early pain relief. This also verifies the possible mechanism of better early pain relief in PCKP, i.e., the “cement dispersion-pain relief” correlation. This is highly consistent with the findings of Yuntao et al. (2025); that is, better cement diffusion leads to better early pain relief. Therefore, Cheng and Xie (2024) suggested that a unilateral approach is recommended for level I OVCFs, whereas a bilateral approach is preferred for levels II and III OVCFs. The purpose of this approach is to achieve better vertebral height regression and cement filling diffusion. In a related study, Jia et al. (2025) categorized the cement distribution on postoperative radiographs into four types based on fracture bone marrow edema area (FBMEA) in preoperative MRIs of patients with OVCFs. This finding further indicates that appropriate bone cement use is beneficial for functional improvement, short-term pain relief, and reduction in the vertebral body recollapse rate. This underscores the necessity of closely monitoring the status of bone cement and its effectiveness in filling the vertebral body during treatment, with the aim of ensuring treatment efficacy and mitigating complications (Bian et al., 2024). In this study, we demonstrated that in the absence of spinal cord and nerve root injuries, there was no correlation between early pain relief and cement leakage after vertebroplasty. However, the medium- and long-term efficacy of the treatment may have a strong correlation with cement leakage, especially in cases of intervertebral cement leakage. This may be due to the deterioration of the local biomechanical environment, which increases the risk of secondary proximal vertebral fracture (Xie et al., 2025). In this study, the amount of cement used was significantly higher in the PCKP group (4.75 ± 1.28 mL vs. 3.25 ± 1.12 mL), yet the leakage rate was still significantly lower than that of UPKP (10.45% vs. 26.39%), and the difference was even more pronounced in moderate and severe cases (21.13% lower leakage rate). We have determined that UPKP utilizes a linear bone drill and a balloon with the puncture biased to one side. To achieve symmetric dispersion of the bone cement during the operation, it is necessary to rely on the high-pressure injection of the bone cement to compensate for the dispersion defects. This results in a significant increase in the risk of cement leakage with an increase in the amount of cement injected. In contrast, PCKP utilizes a distinct curved bone drill, a deflectable balloon, and directional cement infusion instruments, enabling the creation of the bony cavity and low-pressure infusion. This approach increases the dose of bone cement and reduces the leakage rate to a certain extent. Concurrently, this phenomenon indicates that the risk of cement leakage is not solely associated with the dose but rather with the congruence between the perfusion pattern and the bone microstructure.

Despite the significant pain relief advantage of PCKP in the early postoperative period (2 days postoperatively) in the present study, the VAS scores and functional recovery (ODI) effects converged between the two groups of patients at 3, 12, and 24 months postoperatively (p > 0.5). The failure of PCKP’s early pain relief advantage to be sustained over time is a significant discrepancy with the structure of some of the current studies (Fu et al., 2023; Huang et al., 2024). Lindsay et al. (2001) showed that OVCF patients had a 20% risk of subsequent fracture within 1 year once they became symptomatic. A comprehensive analysis of numerous studies (Li et al., 2023; Pan et al., 2023) revealed that satisfactory cement distribution in vertebroplasty can achieve enhanced biomechanics, improved clinical outcomes, and reduced re-fracture rates. However, our current study demonstrated that there was no statistically significant difference in the postoperative vertebral re-fracture rates between the two patient groups. We conducted a thorough investigation to elucidate the reasons behind the early benefits of PCKP not being sustained. We hypothesize that this phenomenon may be attributable to the following factors. First, the study is limited by its single-center design and small sample size, which may lead to a statistically significant increase in the risk of class II error. This is particularly salient given that re-fracture is a relatively low-probability event that necessitates verification by additional centers and large-scale cohorts. Second, bone metabolic imbalance is a fundamental driver of re-fracture, and the current clinical focus of both patients with OVCFs and spine surgeons may be overly concentrated on treating the fracture itself as a complication and trivializing the etiologic treatment of osteoporosis. Numerous studies have established that anti-osteoporosis treatment is a protective factor against vertebral re-fracture (Yang et al., 2025; Lu et al., 2024). Furthermore, the incidence of vertebral re-fracture correlates with the patient’s own BMD and postoperative anti-osteoporosis (Prost et al., 2021; Takahashi et al., 2019). Finally, the treatment of OVCFs is a long-term, chronic process, which emphasizes the need to prioritize patient compliance with standardized anti-osteoporosis treatment and to enhance compliance to the greatest extent possible to ensure therapeutic efficacy. In a real-world study by Zou et al. (2024), it was observed that the percentage of patients using anti-osteoporosis drugs 6 months after vertebral body strengthening was low, with only approximately 7% using denosumab and 13%–15% using oral bisphosphonates. The persistent nature of osteoporosis engenders an elevated risk of vertebral re-fracture.

It is imperative to acknowledge that even with standardized anti-osteoporosis treatment, the correction of bone metabolism in elderly patients with OVCF necessitates a protracted recovery period, accompanied by a “drug response–bone metabolism repair” refractory period. Tang et al. (2024) demonstrated that there is a gradual and persistent loss of height of cement-reinforced vertebrae in the postoperative period. It is important to note that all current anti-osteoporosis therapeutic agents work by promoting osteogenesis or decreasing osteolysis and reducing fracture occurrence (LeBoff et al., 2022). All anti-fracture medications treat but do not cure osteoporosis. Once the medication is discontinued, bone deterioration returns sooner or later, and the risks of osteoporosis and fracture remain even normal BMD has been achieved on follow-up assessment after anti-fracture therapy. In addition, Reid and Billington (2022) demonstrated that anabolic drugs exhibit superior anti-fracture efficacy and more substantial increases in BMD compared to anti-bone resorption drugs. Nevertheless, the effects of anabolic drugs are transient, necessitating a transition to anti-bone resorption drugs. Consequently, to reduce the re-fracture rate in our clinic, it is essential to implement a multifaceted approach that incorporates anti-osteoporotic drugs (which promote osteogenesis and inhibit osteoblasts), adequate intake of calcium and vitamin D (the basic medication), avoidance of smoking and excessive alcohol intake, weight-bearing and resistance training, and the prevention of falls. Therefore, long-term postoperative maintenance of outcomes in patients with OVCF may require greater emphasis on anti-osteoporotic therapy to reduce the risk of re-fracture. Consequently, this study challenges the conventional “cement distribution-centered” approach to OVCF treatment and underscores the imperative for a multifaceted strategy that incorporates early mechanical stabilization and prolonged bone metabolism regulation.

This study demonstrated that, for moderate and severe OVCF cases (Genant grade 2–3), PCKP offers clear advantages by enhancing the efficacy of cement distribution (91.04% vs. 76.39%) and mitigating the risk of leakage (10.45% vs. 26.39%). In contrast, for mild OVCF cases (Genant 0–1), UPKP remains a viable option due to its relative ease of operation. However, it is crucial to note that the risk of leakage due to high-pressure perfusion should be carefully considered. The “two-level decision model” developed based on the Genant classification utilizes the “vertebral compression degree” as the primary index for determining the surgical approach, providing a significant foundation for clinical decision-making. Early satisfactory clinical outcomes can be attained.

In addition, to achieve a satisfactory long-term clinical outcome, the postoperative management of PCKP and UPKP should be based on a strategy of “treating both the symptoms and the root cause,” with short-term relief of acute pain through vertebroplasty and long-term stepwise anti-osteoporosis (calcium supplementation, promotion of osteogenesis, and inhibition of osteoclastogenesis). A stepwise intervention is recommended, including restoration of vertebral height, early pain relief, and restoration of function through PCKP/UPKP in the acute phase; maintenance of calcium + vitamin D + bisphosphonate/teriparatide/romosozumab combination therapy for 24 months postoperatively; detection of dynamic changes in bone metabolism through bone mineral density; and integration of fall prevention and rehabilitation to form a “surgery-drug-behavioral” strategy, also known as the “surgery-drug-behavior” trinity management model (LeBoff et al., 2022).

This study is not without its limitations. The single-center design may introduce selection bias, the 24-month follow-up makes it difficult to assess ultra-long-term (>5 years) biomechanical changes, and bone metabolism markers (e.g., β-CTX and P1NP) and further quantification of treatment adherence were not included. Future studies must conduct multicenter RCTs to reduce selection bias and improve the reliability and generalizability of the results. The development of a prediction model integrating finite element analysis and “OVCF classification–procedure matching” will facilitate more precise procedure selection and enhance therapeutic efficacy. Furthermore, investigating the synergistic mechanisms between anti-osteoporosis medications and bone cement materials has the potential to yield novel therapeutic strategies and provide a theoretical foundation for the treatment of OVCFs.