INTRODUCTION
Osteoporotic vertebral compression fractures are a significant healthcare concern, affecting a substantial portion of the elderly population. These fractures often lead to chronic pain, decreased mobility, and diminished quality of life. Kyphoplasty (KP) and vertebroplasty (VP) are two minimally invasive surgical techniques widely employed for stabilizing these fractures and alleviating associated symptoms (1). Although both procedures have demonstrated efficacy in pain relief and fracture stabilization, there remains a debate regarding their comparative effectiveness. Some studies suggest that KP may be superior in reducing cement leakage and improving postoperative vertebral body height, although it is more expensive and time-consuming than VP (2). Other research indicates no significant differences in long-term pain and disability outcomes between the two methods, highlighting the need for further comparative studies (3).
Recent advancements in materials and techniques, including the use of alternative cements to polymethylmethacrylate (PMMA), have opened new avenues for improving the safety and efficacy of these procedures (4). Both methods are effective in controlling pain in patients with osteoporotic vertebral fractures. Although KP is a more effective method for restoring collapsed vertebral fractures, its long-term results are controversial.
In this study, we compared the long-term clinical and radiological outcomes of patients with osteoporotic vertebral fractures who underwent KP and VP and specifically evaluated whether KP was superior to VP in terms of long-term vertebral height restoration.
MATERIALS AND METHODS
Study Design and Population
Ethics committee approval was obtained from the Ethics Committee of Gazi University for this retrospective study (approval number: E-77082166-604.01.02-830153, date: 19.12.2023). This retrospective study encompassed 66 patients who underwent either KP or VP for vertebral compression fractures at Gazi University Hospital, Ankara, of whom 33 were excluded because of the lack of pre- and postoperative clinical and radiological data. The final cohort comprised 33 patients who underwent both preoperative and postoperative assessments and maintained a follow-up period of at least 24 months. Patients with metastatic spinal fractures, those undergoing surgery for fractures and/or degenerative causes of the spine, and those with instrumentation in the spine were excluded from the study.
The 33 patients included in the study were divided into two groups according to the surgical procedure performed: KP (n=16) and VP (n=17).
Data Collection
Clinical assessments were performed using the Oswestry Disability Score, visual analog scale (VAS), and EuroQol- 5 Dimension (EQ-5D) scores. Radiological evaluations encompassed the measurement of anterior and middle column height, along with the assessment of the kyphotic angle of the fractured vertebrae. All radiological evaluations were performed on plain radiographs of the spine taken in the standing position. The local kyphosis angle was obtained by measuring the Cobb angle between the inferior endplate of the vertebra above the fractured vertebra and the inferior endplate of the fractured vertebra. These evaluations were conducted at preoperative, early postoperative, and final follow-up visits (Figure 1, 2, 3). These measurements were obtained using the hospital’s PACS system (ExtremePACS 2015 version 4.3).
The Oswestry Disability Index (ODI) is a scale used to assess disability in relation to back pain and quality of life. It consists of 10 questions. Each question has five possible answers, and a percentage of the answers is calculated. Patients with a score of 0-20 have mild back problems, whereas patients with a score of 80-100 have severe back problems and are bedridden. The EQ-5D is a preference-based measure of health-related quality of life that includes one question for each of 5 dimensions, including mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The EQ-5D questionnaire also includes a Visual Analogue Scale (VAS), which allows respondents to report their perceived health on a scale from 0 (worst possible health) to 100 (best possible health) (5).
Subsequent to data collection, rigorous statistical analyses were performed to draw meaningful conclusions. Comparative analyses were specifically conducted between the results obtained from the KP and VP patient groups.
Surgical Techniques
In KP, patients were positioned prone under general anesthesia.
The procedures were conducted under fluoroscopic guidance. For each targeted vertebra, a 1 cm skin and subcutaneous incision was made approximately 1.5-2 cm lateral to the pedicle. A trocar was inserted between the center and edge of the pedicle (between 1-3 o’clock on the right side pedicle and 9-11 o’clock on the left side pedicle). Under posteroanterior (PA) fluoroscopic guidance, the trocar was advanced approximately 2-3 cm, ensuring that it did not cross the medial line of the pedicle. Lateral fluoroscopic images of the vertebral column were obtained. Once it was confirmed that the tip of the trocar had passed the posterior wall of the vertebral corpus and was inside the corpus, the trocar was further advanced. Upon reaching approximately one-fourth of the anterior part of the vertebral corpus, the trocar was removed, and its position within the corpus was confirmed using a probe. A working cannula was then placed in the trocar position. KP balloon instruments were inserted through the working cannula and inflated with contrast material. The expansion of the kyphotic vertebra was monitored by fluoroscopy. This procedure was performed bilaterally. After sufficient correction of the vertebra was observed, the KP balloon was deflated and removed. Before injection of PMMA cement, a contrast material was used to check for vascular leakage. Then, PMMA cement was slowly injected, ensuring that its consistency was not too fluid. Approximately 3-4 cc of PMMA cement was used in the thoracic region and 5-6 cc in the lumbar region. During the injection, both lateral and PA images were taken to ensure that the PMMA cement did not leak outside the corpus, especially into the spinal canal.
VP was performed similarly to KP under general anesthesia in the prone position and guided by fluoroscopy. Following the placement of the working cannula into the vertebral corpus, PMMA cement was directly injected without balloon KP. Care was taken to ensure that the PMMA cement did not leak, especially into the spinal canal, during fluoroscopic monitoring.
To prevent possible complications, we evaluated venous extravasation by injecting contrast material before VP and KP. We also check the fluidity of PMMA and inject PMMA after it has a consistency similar to toothpaste.
Both KP and VP patients were mobilized at the 4th hour after surgery. None of the patients required the use of a brace.
Statistical Analysis
The analysis was conducted using SPSS version 27. Descriptive statistics were computed, and the Shapiro-Wilk test was used to evaluate the normality of distributions. Pearson’s and Spearman’s correlation analyses were performed as appropriate. The Wilcoxon signed-rank test assessed differences in vertebral height measurements preoperatively and postoperatively. The Mann-Whitney U test was used to compare the KP and VP groups in terms of measurements and scores.
RESULTS
The KP patients ranged in age from 43 to 84 years with a mean age of 62.81 [standard deviation (SD)=20.06] years and a mean follow-up of 95.65 (SD=39.80) months. The VP group ranged in age from 42 to 90 years with a mean age of 68.29 (SD=18.06) years and a mean follow-up of 89.72 (SD=43.75) months. There were no significant differences in the mean age and follow-up between KP and VP patients (Table 1). Fracture levels were generally located in the thoracolumbar region (Table 2).
The mean functional status of the patients in the KP group as measured by the ODI was 26.88 (SD=13.31), indicating moderate disability. The quality of life, as assessed by the EQ-5D index, had a mean value of 0.865 (SD=0.099). Preoperative vertebral anterior column height measurements averaged 1.15 cm (SD=0.61), early postoperative measurements averaged 1.89 cm (SD=0.36) and at the last follow-up, 1.44 cm (SD=0.415). The vertebral mid-column height was 1.33 cm (SD=0.381) preoperatively, 1.91 cm (SD=0.322) early postoperatively, and 1.40 cm (SD=0.312) at the last follow-up (Table 3).
In the VP group, the ODI indicated a higher level of disability with a mean score of 31.53 (SD=21.02), whereas the EQ-5D index was comparable to the KP group with a mean score of 0.871 (SD=0.100). The preoperative vertebral measurements in this group averaged 1.25 cm (SD=0.55), the early postoperative measurements demonstrated a significant increase, averaging 1.27 cm (SD=0.362) and at the last control 1.28 cm (SD=0.34). The vertebral mid-column height was 1.41 cm (SD=0.478) preoperatively, 1.61 cm (SD=0.488) early postoperatively, and 1.41 cm (SD=0.483) at the last control (Table 3).
There was no significant change in vertebral posterior column height in either group preoperatively, early postoperatively, or at final follow-up.
For both groups, the collected scores and measurements displayed a range of distributions, with some variables exhibiting non-normal distribution characteristics, as indicated by their skewness and kurtosis values. This data variability underscores the heterogeneity within the patient population and the outcomes of the surgical procedures.
Normality of the Data
Shapiro-Wilk tests showed that most variables in the KP and VP groups did not deviate significantly from a normal distribution. However, certain variables in each group, such as age distribution and specific preoperative and postoperative measurements, showed significant deviations from normality (Table 4).
Correlation Analysis
Pearson correlation analyses within the KP group indicated significant negative correlations between age and specific postoperative measurements and strong relationships between disability, quality of life, and pain levels. The VP group showed similar patterns, with age negatively correlated with certain preoperative and postoperative measurements and significant interrelations among disability, quality of life, and pain scores.
Wilcoxon Signed-Rank Tests
In the KP group (n=16), a Wilcoxon signed-rank test revealed significant changes in vertebral measurements from the preoperative to postoperative stages. There was a significant increase in early postoperative vertebral anterior column height measurement (Z=-2.699, p=0.007) and vertebral mid-column height measurement (Z=-3.319, p=0.001), but no significant change in vertebral posterior column height measurement (Z=-0.586, p=0.558). A significant decrease was observed in the postoperative local kyphosis angle measurement (Z=-3.527, p<0.001) (Table 5).
In the VP group (n=17), the test also indicated significant changes. There was a significant increase in the postoperative vertebral anterior column height measurement (Z=-3.461, p=0.001) and vertebral mid-column height measurement (Z=-2.126, p=0.033), whereas no significant change was observed in the vertebral posterior column height measurement (Z=-0.577, p=0.564). A significant decrease was noted in the postoperative local kyphosis angle measurement (Z=-2.812, p=0.005) (Table 6).
Mann-Whitney U Test Findings
The Mann-Whitney U test demonstrated significant differences between the KP and VP groups in terms of ODI scores, postoperative anterior column, mid-column height, and local kyphosis angle. No significant differences were found between the groups in other variables, including age, EQ-5D index, VAS, and various preoperative and postoperative measurements (Table 7).
DISCUSSION
Our study compared the outcomes of KP and VP in terms of restored vertebral height, quality of life, disability, and pain scores. The findings indicate that both procedures are effective in managing vertebral compression fractures although there are nuanced differences between them.
Comparative Efficacy in Pain and Disability Management
The results of our study align with those found in previous research. A systematic review and meta-analysis included 29 studies with 2,838 patients, and found no significant differences in mean pain scores postoperatively and at 12 months between the KP and VP groups. This study also reported similar disability scores postoperatively and at 12 months for both groups (3). These findings suggest that both KP and VP are equally effective in managing pain and disability associated with vertebral compression fractures. In another study from Türkiye, both KP and VP were found to be effective in improving functional recovery and pain relief in patients with osteoporotic vertebral fractures. While KP showed slightly better radiological outcomes, this difference was not clinically significant, leading the authors to recommend VP for its simpler management (6).
A study examining long-term outcomes over a 5-year period showed only subtle differences between KP and VP, suggesting the use of VP over KP considering treatment costs (7). Another study assessing KP outcomes over 3 years found significant improvements in pain and mobility compared with controls, as well as a reduced risk of new vertebral fractures (8). Additionally, a study evaluating VP outcomes over a 29-month period reported significant reductions in pain and disability scores, with less intense analgesic use compared with conservative therapy (9). In our study, the mean follow-up time was 96 (SD=39.80) months, which is consistent with the results of other long-term studies. Our findings show that there were no significant differences in pain and quality of life scores between patients undergoing both KP and VP procedures.
Vertebral Height Restoration and Kyphosis Reduction
Our findings on vertebral height restoration are particularly noteworthy. We observed significant changes in both vertebral height measurements and local kyphosis angle in the early postoperative period in the KP group. This is consistent with another study, which found that KP was superior to VP in terms of increasing postoperative vertebral body height (2,10). Although the final follow-up radiographs of KP patients showed better results in terms of both vertebral height and local kyphosis angle, there was a significant loss of both vertebral height and local kyphosis angle in KP patients compared with early postoperative values. Biomechanical studies also support the initial superiority of KP in increasing vertebral body height and reducing kyphosis although these gains may diminish with repetitive loading (11).
Complications and Cost-Effectiveness
There were no serious intraoperative or early postoperative complications in either group of patients. Two patients who underwent KP had adjacent vertebral fractures at 3 and 6 months postoperatively. Three patients who underwent VP had adjacent vertebral fractures at 8 and 13 months of age. None of the patients underwent surgery for an adjacent vertebral fracture. The fractures healed conservatively during follow-up. With the exception of adjacent vertebral fractures, no complications were observed in the patients included in this study.
While KP has advantages in vertebral height restoration, it is important to consider the balance of benefits and risks. KP is associated with lower odds of new fractures and less extraosseous cement leakage than VP. However, the more complex nature of KP, including its higher cost and longer operative time, raises questions about its cost-effectiveness, especially when the differences in pain and disability outcomes between the two procedures are statistically insignificant (2,3). Complications related to cement extravasation, such as compression of neural elements and venous embolism, are rare but more common with VP (11). In our study, no serious complications related to PMMA cement leakage were observed. Cement leakage into the intervertebral disk space occurred in one patient who underwent KP and in three patients who underwent VP. However, because these patients did not exhibit any clinical problems during follow-up, no additional procedures were necessary. This finding highlights the relative safety of both procedures in terms of cement leakage, with clinical outcomes remaining unaffected despite this occurrence.
Study Limitations
One of the main limitations of our study is that it was retrospective and the number of patients included in the study was relatively small. The lack of data on patients’ body mass index, comorbidities, and bone mineral density are also limitations of the study. In addition, the wide age range of the patients included in the study and the inability to classify them according to age are also important limitations of our study.
CONCLUSION
In conclusion, our study contributes to the ongoing debate on the comparative efficacy of KP and VP. While both procedures are effective in managing pain and disability, KP appears to offer better outcomes in terms of vertebral height restoration and reduced complications related to cement leakage. However, its higher cost and longer operative time necessitate further research to establish its cost-effectiveness. Future studies should focus on long-term outcomes and identify specific patient subgroups that may benefit more from one procedure than the other. This would enable more personalized treatment approaches and optimize outcomes for patients suffering from vertebral compression fractures.
Ethics
Ethics Committee Approval: Ethics committee approval was obtained from the Ethics Committee of Gazi University for this retrospective study (approval number: E-77082166-604.01.02-830153, date: 19.12.2023).
Informed Consent: Retrospective study.
Authorship Contributions
Surgical and Medical Practices: A.C.B., F.A., A.A., A.Ş., Concept: A.C.B., F.A., A.Ş., Design: A.C.B., A.A., A.Ş., Data Collection or Processing: M.F.T., M.M.C., C.İ.G., Analysis or Interpretation: A.A., M.F.T., M.M.C., Literature Search: A.A., Writing: A.C.B., F.A., A.A.
Conflict of Interest: No conflict of interest was declared by the authors.
Financial Disclosure: The authors declared that this study received no financial support.