KYPHOPLASTY AND VERTEBROPLASTY IN THE TREATMENT OF OSTEOPOROTIC VERTEBRAL FRACTURES

ABSTRACT Objective: To compare these procedures in the treatment of osteoporotic vertebral compression fractures. Methods: Patients who underwent vertebral augmentation procedures between March 2010 and October 2016 were selected for the study. Kyphosis, anterior vertebral height, Oswestry Disability Index (ODI), Visual Analog Scale (VAS), number of portals, cement volume, and complications were recorded. The results were analyzed by difference of the means. Results: Sixty-eight patients were selected, accounting for 105 procedures. A statistically significant improvement was observed in VAS and ODI with both procedures (p<0.001) without statistically significant difference between them, regardless of the number of portals or cement applied. There was a high correlation between kyphosis correction and ODI improvement (p =0.012). Conclusions: Both vertebroplasty and kyphoplasty are effective procedures for the treatment of vertebral compression fractures. We found no significant difference between both procedures. The high correlation between improvement of kyphosis and ODI suggests that these procedures are better than conservative treatment to improve the quality of life of patients, however more studies are required to reach a final conclusion. Level of Evidence III; Retrospective comparative study.


INTRODUCTION
Osteoporosis is a health issue of global importance.5][6][7] Unlike other types of osteoporotic fractures, OVFs are usually not associated with trauma. 8Nonetheless, OVFs are associated with a significant worsening of the morbidity and mortality of patients. 6,9Over time, the patients with OVF can suffer from chronic pain, reduced quality of life and functionality, low self-esteem, risk of other fragility fractures, 10 medullary compression, and changes in pulmonary function. 11As regards mortality, an increase of 32% has been reported, adjusted for the age of the patients with OVF. 12 Currently, the gold standard in treatment of OVFs remains conservative based on analgesics, rest, and immobilization, 8,13 however, conservative treatment with long periods of inactivity in the elderly patient can produce pneumonia, bed sores, venous thromboembolism, new OVFs, and even death. 13,14Coupled with this, in some cases the patients continue to have pain, as well as a reduction in the quality of life despite having undergone appropriate conservative treatment. 8,15It is for these patients that vertebral augmentation procedures have appeared as an useful alternative in the treatment of OVFs. 6,8,15,16mong vertebral augmentation procedures, two have shown to be more effective: vertebroplasty and balloon kyphoplasty (Figure 1). 6,8,16Vertebroplasty was first described for the treatment of aggressive vertebral hemangiomas of the lumbar spine. 17Bone cement is injected into the vertebra via a transpedicular approach, which helps to stabilize the vertebral fracture, improving both strength and stability.In balloon kyphoplasty, a cavity is created in the vertebra using an inflatable balloon, thus reducing the pressure from the injection and restoring vertebral height. 8ertebroplasty and kyphoplasty have been shown to be effective in improving both pain and the quality of life of patients with OVF, even when compared to conservative treatment. 6,15,16owever, there is still controversy around whether any of these treatments is more effective or safer in terms of the incidence of complications. 6,13,15,16,18Another controversy revolves around comparing the effectiveness of and complications resulting from the use of one versus two portals. 5,6,16,19For this reason, the objective of this study is to compare the results obtained and the incidence of complications from these two procedures in patients treated in our facility.

Patients
With the prior authorization of the Institutional Review Board, we conducted a retrospective study of the patients with vertebral compression fractures attended by the team of Dr. Hugo Alberto Santos Benítez at the Ruber Quirón Juan Bravo Hospital in Madrid, Spain, from January 2009 to December 2016.From among those patients, those who had undergone vertebroplasties or kyphoplasties were selected.No distinction was made by the age, sex, number of affected levels, or associated pathologies of the patients.Patients who had undergone vertebral augmentation for other causes (hemangiomas, metastases, multiple myeloma, etc.) or prior spine surgeries were excluded.Likewise, those patients without complete medical records were excluded.Due to the retrospective nature of the study, it was not necessary for the patients to sign the informed consent form.

Parameters evaluated
General patient data were collected, including age, sex, levels affected, the Oswestry Disability Index (ODI), and pre-and postoperative pain as assessed by the Visual Analog Scale (VAS).The angle of kyphosis, measured using the Cobb method, and the anterior vertebral height were evaluated radiographically before and after surgery.A preoperative STIR sequence magnetic resonance was also performed to determine whether the fracture was recent.Regarding the surgical event, data about the number of portals used per vertebral body, the volume of bone cement injected into the vertebral body, the presence and location of cement leakage, and the presence of other complications were collected.During postoperative follow-up, information was collected about the appearance of new OVFs, for which a new vertebral augmentation procedure would be performed.

Statistical analysis
Statistical analysis was conducted with SPSS v 22 software (SPSS Inc., Chicago, IL, USA).The categorical variables were presented as percentages and the continuous variables as averages + standard deviation (SD).We performed comparison group analysis by means of Chi square (X 2 ) for the categorical variables and with the Student's t test for the continuous variables, and also searched for a correlation between the quantitative variables with the Pearson correlation.The confidence interval was established at 95%, with a value of p<0.05 being statistically significant.

RESULTS
Of the 99 patients treated during the period, 68 met the study criteria.During follow-up 10 cases of new fractures were encountered, giving a total of 105 vertebral augmentations performed during the period.The average age of the patients was 76.3 years + 11.3, with a predominance of females.The demographic characteristics of the patients, including age, sex, number of affected levels, and the appearance of new fractures are presented in Table 1.The general procedure, including the number of kyphoplasties and vertebroplasties, the number of portals, and the occurrence of cement leakage are found in Table 2.The most often used technique was kyphoplasty with one portal.In terms of the fracture levels, we observed that the vertebrae with the highest incidence of fracture were L1, L2, and T12 (T6=1, T7=3, T8=5, T9=3, T10=5, T11=5, T12=13, L1=27, L2=20, L3=8, L4=8, L5=7).
Comparing the use of 1 versus 2 portals to perform the vertebral augmentation procedure, we did not observe a statistically significant difference in the occurrence of complications (p=0.869), the incidence of new vertebral fractures (p=0.172), or cement leakage (p=0.234).Similarly, we did not observe any statistically significant differences between the use of 1 or 2 portals in ODI improvement (3.757%; p=0.410),VAS for pain (0.04; p=0.939), kyphotic angle (0.41°; p=0.637), or vertebral height (0.1%; p=0.97).
Regarding the volume of cement administered, no statistically significant correlation was observed with the development of complications (p=0.612), the presence of cement leakage (p=0.375), or the appearance of new fractures (p=0.096);nor did we find any statistically significant correlation between the volume of cement administered and the correction of the kyphotic angle (0.070, p=0.479), the anterior vertebral height (0.083, p=0.401), improvement in the ODI (0.361, p=0.361), or improvement in the VAS for pain (0.011, p=0.909).Likewise, no statistically significant correlation was found between correction of the kyphotic angle and improvement in the VAS for pain (0.051, p=0.604), between vertebral height and improvement in the VAS for pain (0.111, p=0.156), or between vertebral height and improvement in the ODI (0.069, p=0.483).However, a strong correlation was found between correction of the kyphotic angle and improvement in the ODI (0.905, p=0.012).Finally, we did not find any correlation between the appearance of new OVFs and correction of the kyphotic angle (0.17, p=0.911) or correction of the anterior vertebral height (3.59, p=0.435).

DISCUSSION
1][12] Even though conservative treatment continues to be the gold standard in many centers, 8,13 several studies have reported that vertebral augmentation procedures have shown to be an effective treatment, and even superior to conservative treatment in some studies. 6,15,16n this study, we observed a significant improvement in the patients who were submitted to vertebral augmentation procedures, both in terms of their functionality (ODI) and pain (VAS), which coincides with other similar studies that have been conducted. 6,13,16It is important to note that there is still controversy around the superiority of either of the vertebral augmentation procedures (kyphoplasty or vertebroplasty).Multiple studies have reached the conclusion that there is no difference between the two procedures in terms of improvement in pain and functionality, which is in agreement with the results obtained in our study. 6,13,15,16As regards correction of the angle of kyphosis and of vertebral height, we did not find any statistically significant differences in our study, while other studies favor kyphoplasty over vertebroplasty in order to achieve greater correction of the kyphotic angle. 13,15It is possible that this finding is due to the fact that the radiographic measurements of the patients were made by long-term radiographic evaluations and not with a non-standardized technique, as well as because of the lack of homogeneity in the population and the retrospective study design.Thus, a new prospective study in which vertebral height and kyphotic angle are measured serially, comparing both procedures, would be useful.Another important controversy is the comparison between the use of 1 or 2 portals in vertebral augmentation treatments. 5,16,19lthough this controversy is mainly focused on kyphoplasty, in our study we did not find any significant differences between the use of 1 or 2 portals in either vertebroplasty or kyphoplasty, which coincides with multiple previously conducted studies. 5,16,19herefore, from our point of view, a decision will depend on the surgeon's experience, as well as on the situation and the quantity of fractures to be treated.
8]20 In our study, we did not observe any relationship between the volume of cement applied and the development of complications with cement leakage or the appearance of new OVFs, or between the volume of cement and both radiographic and clinical improvement.These results are consistent with those reported in the literature, 6,16,20 so we are not able to recommend the ideal volume of cement for obtaining a satisfactory result or minimizing the occurrence of complications.
A relevant result in this study was the high correlation found between the correction of the kyphotic angle and the patient's functional improvement as evaluated by the ODI, which according to the Pearson correlation coefficient was very high (0.905).Currently, there are few studies that have established a correlation between correction of kyphosis and improvement in the quality of life, and there are contradictory results on this point. 16,21Unfortunately, as previously mentioned, in our study we did not find any significant differences between vertebroplasty and kyphoplasty for the correction of kyphotic angle.However, several studies agree that the advantage of kyphoplasty over both vertebroplasty and conservative treatment lies in the possibility of a greater correction of the kyphosis. 13,15,16There are, however, studies that indicate excessive correction of kyphotic angle as a risk factor for the development of new OVFs adjacent to the treated segment. 6,16,20Despite this, in our study we did not find any relationship between the correction of kyphotic angle and the development of new OVFs, either adjacent or not adjacent.Therefore, adding the high correlation between improved quality of life of the patients and correction of their kyphosis to the fact that no significant difference in the appearance of new OVFs was found, balloon kyphoplasty could be recommended over vertebroplasty.However, it is important to emphasize the need to conduct more studies, mainly of a prospective nature, in which both correction of kyphotic angle and improvement in patient functionality are taken into account.
Our study included patients treated by Dr. Hugo Santos at the Ruber Quirón Juan Bravo Hospital.The fact that the patients were attended by a single surgeon allowed us to reduce the bias in the procedure results.It is important to note that the patients treated in this facility are not covered by the social security system, but rather by private medical insurance companies.This allowed us to give more timely attention to the patients, obtaining adequate results with shorter wait times.In our experience, we have observed that priority attention with shorter wait times to patients with OVF allows a better postoperative prognosis.Timely patient care has improved through the training of human resources in health for adequate diagnosis and timely referral to the proper patient study protocol.Several examples of these human resources in health are services like the Pain Unit, First Contact Physicians, and Rheumatology, among others.Another important factor that has allowed us to improve patient care is the ability to receive laboratory tests and image studies in short periods of time, such as STIR-sequence magnetic resonance being available within 2 to 48 hours.This permits timely programming and rapid care for patients with this condition.Our patient care protocol can be summarized as follows: 1) preferential consultation appointment, generally referred by other patient cares services; 2) magnetic resonance in the STIR sequence to identify the acute-phase levels affected in order to make a surgical decision (Figure 2); 3) preoperative radiographic control study one day prior to surgery to assess the possible increase in the deformity of the patient; 4) timely surgical treatment; 5) follow--up by the bone pathology unit using the study complete protocol, as well as follow-up by our service.

CONCLUSIONS
In this study, we concluded that both kyphoplasty and vertebroplasty are useful tools in the treatment of OVFs, achieving significant improvement in the quality of life and pain of the patients.In addition, we found a high correlation between improvement of the kyphotic angle and improvement in the ODI, which represents a better quality of life for patients, with procedures that correct kyphotic angle.It should be noted that, despite the fact that our study did not observe any significant differences between the two procedures, other studies found that balloon kyphoplasty enabled better correction of the kyphotic angle, which is why in our experience it is the most recommendable procedure if improvement in the quality of life of the patient is expected.However, more studies must be conducted to reach a final conclusion.The treatment of these patients must be prioritized to obtain a better patient prognosis.In addition to the initial medical visit, magnetic resonance in the STIR sequence, and radiographic studies should be conducted and surgical treatment should be performed in a timely manner.
All authors declare no potential conflict of interest related to this article.

Figure 1 .
Figure 1.Patient with osteoporotic vertebral fractures at multiple levels treated by vertebroplasty.

Figure 2 .
Figure 2. Magnetic resonance of the thoracic spine in phase T1 (A), T2 (B), and STIR (C), showing the difference in intensity, permitting differentiation between acute and chronic fractures.

Table 2 .
Characteristics of the performed procedures.