The puncture route of PVP mainly includes conventional transpedicular approach, extrapedicular approach and transtransverse process root-pedicle approach. Whether to perform unilateral or bilateral puncture for PVP remains controversial, but unilateral approaches is gradually accepted due to less surgery time, radiation dosage compared to bilateral approaches [10, 11]. The Conventional unilateral transpedicular approach is a common and safe puncture route for PVP and PKP, and it has been used in clinical practice for decades. However, numerous associated complications and problems will still been reported, such as puncture difficulty, pedicle fracture, cement leakage, and cement distribution [12, 13]. Therefore, some scholars have used the extrapedicular approach and TPRPA in clinical practice, but extrapedicular approach is mainly used in cases with mid-thoracic vertebra or thin pedicle due to the risk of vascular injury [14–18]. Yan L, et, al. reported TPRPA is a relatively safe and effective approach with less radiation dosage and shorter surgical time [19, 20]. In this study, although no specific comparative analysis was conducted on the number and time of X-ray fluoroscopy between the two groups, the total surgical time of the TPRPA group was shorter than that of the CTPA group. As we know, PVP surgery requires frequent X-ray fluoroscopy throughout the whole process, so we can conclude that the number of X-ray fluoroscopy in the TPRPA group is lower than that in the CTPA group. Of course, this result requires the establishment of the above indicators for rigorous comparative analysis. All patients in the TPRPA group had no intraoperative pedicle fracture or difficulty in puncture, so we also believed that this technique was safe and reliable when applied to the lumbar spine, which was basically consistent with previous studies.
VAS and ODI score are important indicators to evaluate pain degree and quality of life of patient. Therefore, it is commonly used for evaluating the clinical efficacy before and after treatment. In this study, we compared the clinical effectiveness between CTPA and TPRPA group, through VAS and ODI. Our study showed that postoperative pain symptoms were significantly relieved and quality of life was significantly improved. This results were embodied in the significant changes in VAS and ODI scores. The results support that both CTPA and TPRPA PVP were effective methods for OLCF. In addition, the injection amount of bone cement was different between the two groups, but there was no difference in a therapeutic effect, this result suggested that the clinical effect of PVP was independent of the cement volume.
To our knowledge, many scholars have studied the relationship between bone cement distribution patterns and bone cement leakage and therapeutic effect. Bin et al . found that all cement distribution patterns can relieve pain and reduce spinal biological curvature, but extensive distribution of treated vertebrae has certain advantages in long-term pain relief. Lei et al . proved that sufficient contact of bone cement with upper and lower endplates is an ideal distribution type, which can better maintain the height of the fracture vertebral and reduce the risk of long-term vertebral re-fracture of the vertebral body . Therefore, lateral radiographs were used in this study to evaluate the distribution type of bone cement and compare the ratio of type 1 distribution between the two groups. However, several factors were found to influence the bone cement distribution during PVP procedures. Such as uneven bone density, fracture classification, injection techniques. In our opinion, injection technology is a factor that the surgeon can control. The puncture point of CTPA goes through the articular process and more close to the inner wall of the pedicle, extraversion angle is not enough. By contrast, the TPRPA puncture point is more lateral to the facet joint, with a larger extraversion angle, and is more likely to reach the optimal target position of the anterior and middle 1/3 of the vertebral body. In this study, compared with the CTPA group, TPRPA group had more bone cement injection amount and more type 1 distribution. This result indicated that the injection amount of bone cement was correlated with its distribution. We hold the point that in the absence of bone cement leakage, increasing the amount of bone cement injection can improve the injection pressure and promote the distribution of bone cement. However, the relevant conclusion needs to be further verified. We summary that TPRPA has following advantage: 1) Ideal target puncture, bone cement can diffuse to the anterior and contralateral vertebra; 2) Apply stratified injection technology, can inject more bone cement and obtain extensive distribution; 3) Use the root of the transverse process for positioning, with a clear structure, and bitter hand feel, easier to succeed and shorten operation time.
In this study, bone cement leakage in the two groups was 21.05%(8/38) and 32.35%(11/34) respectively, but the difference was not statistically significant. The results showed that increasing injection of bone cement could promote the distribution of bone cement, but did not increase the leakage rate of bone cement. However, It is not an ideal method to increase the excess volume of bone cement to obtain extensive distribution of bone cement. Because research based on laboratory biomechanics has found that when the amount of bone cement reaches about 15% of the vertebral body, the stiffness of the damaged vertebral body can be restored. If the amount of bone cement injected exceed this value, there is no obvious benefit, which may result in the asymmetric distribution of bone cement and excessive vertebral stiffness . In addition, increasing the amount of bone cement may increase the risk of cement leakage [24, 25]. Although the exact relationship between the cement amount and cement leakage rate cannot be obtained in this study, we agree with the above viewpoints.