Osteoporotic vertebral compression fractures (VCFs) have a high incidence and have direct and indirect negative consequences on health-related quality of life in elderly patients and costs to the healthcare system.[1,2] Currently, percutaneous vertebroplasty (VP) and balloon kyphoplasty (KP) are widely used in clinical practice. Both procedures are minimally invasive procedure that provides pain relief and stability by correcting kyphosis and body height in patients with osteoporotic compression fractures.[3-5] KP is a minimally invasive intervention method that utilizes an inflatable balloon to create space in the central portion of the vertebral body before cement injection, aiming to restore height as an alternative to VP.[6] One of the main concerns in these procedures is that augmentation with bone cement can lead to the development of new fracture at untreated levels and extravasation of inserted cement.[7-9] In our previous study, we obtained research results indicating that a higher rate of height restoration in the vertebral body is associated with an increased risk of adjacent vertebral fractures.[10] Therefore, we were concerned about the possibility of complications occurring after KP, particularly when performing excessive kyphotic angle correction in cases of significant deformity. So, in this study, we investigated retrospectively the risk of complications comparing radiological and clinical outcomes 1 year after the procedures between VP and KP performed over 10 years period at our institute to evaluate the safety and efficiency of KP.

A total of 115 patients managed with VP and KP were enrolled in this study. They consisted of 63 (54.8%) patients in the VP group and 52 (45.2%) in the KP group. Mean age of VP group was 80.2 (68-95) and 74.2 (65-84) in KP group. The level of fracture was distributed between T6 and L4 spine and was most prevalent on the thoracolumbar junction. There was no significant difference between 2 groups for demographic data statistically including BMD which mostly corresponds to osteoporosis (Table 1).

There was a significant difference in the mean preoperative vertebral body height, local wedge angle and adjacent kyphotic angle (Cobb angle) between the VP and KP groups, respectively (P<0.01). Although the mean volume of polymethylmethacrylate (PMMA) cement per body was not different in both groups (7.3±1.7 mL vs. 7.7±2.6 mL, in the VP and KP group; P=0.41), the restoration rate, degrees of improvement local kyphotic angle and cobb angle were significantly higher after KP as compared with VP (P<0.05) (Table 2). The rate of cement leakage cases was higher in the VP group (19.0%) than in the KP group (11.5%), but a statistically significant difference could not be confirmed (P=0.31). Between the 2 groups, a significant difference in the change of pre- and postoperative restoration rate and 2 angle measurements, but no difference was observed in the incidence of adjacent fractures (P=0.46). Comparing the period of occurrence of adjacent fractures in the 2 groups, it was found that fractures occurred in a relatively short period in the KP group, but there was no statistical significance (P=0.09). At 1 year follow-up, significant improvements in pain evaluated by VAS were shown but there were no statistically significant differences (P=0.56) when comparing the VAS scores between the 2 groups (Table 3).

Patients suffering from compression vertebral fracture will have developed irreversible spinal deformity (kyphosis) associated with several significant health consequences including decreased physical functioning and diminished health-related quality of life,[13,14] increased future fracture risk,[1,15] impaired balance, and increased incidence of falls.[16]

There is still controversy in studies as to whether new vertebral body fractures are a result of the natural progression of osteoporosis or a consequence of augmentation.[17] But restoration of vertebral height and sagittal balance through the interventions is believed to be important in the treatment of long-term increased morbidity and mortality that arises from compression fractures and spinal deformity.[13] A cost-effectiveness study conducted in the United States concluded that both procedures were more cost-effective than conservative treatment,[18] and Svedbom et al. [17] in the United Kingdom argued that KP was more cost-effective than VP.

Several studies have reported that treated fracture transfers excessive load to the surrounding vertebral body due to the biomechanical effect of PMMA cement injected with KP or VP, increasing the risk of adjacent vertebral fractures.[1,4] Kim et al. [9] found an increased risk of new adjacent fracture to level with increased height restoration after vertebral augmentation. For the risk factors for peripheral fractures, biomechanical studies and results suggest that the greater the height and angle resilience, the more fractures there are. Based on this findings, because of the greater degree of height recovery with the KP procedure, new fractures can be expected to be more common after KP.[19]

However, this was not the result found in this study. Same as in our study, Wang et al. [20] concluded that both interventions were considered to have similar risks with subsequent fracture and cement leakage. Ma et al. [21] conducted a meta-analysis that encompassed 12 studies with 1,081 patients, and there were no statistical differences in VAS, Oswestry Disability Index (ODI), cement leakage rates, and adjacent vertebral fracture rates. Zhao et al. [22] also represented both VP and KP showed similar effects on short-term pain relief, posterior vertebral body mass, and adjacent-level fractures.

Rho et al. [23] and Lin et al. [24] reported that leakage of cement into the intervertebral disc during augmenting vertebrae with bone cement increases the risk of new fractures of adjacent vertebral bodies. Komemushi et al. [25] also determined the only independent variable associated with fractures was cement leakage into the intervertebral disc. Based on indirect comparison of KP and VP case series, previous systematic reviews or meta-analyses showed that KP appears to have a substantially lower incidence of cement leakage than VP.[26-28] and it had been suggested that cement leaks into the adjacent intervertebral disc space affect the mechanical loading of either the disc or adjacent vertebrae, which might predispose the patient to an adjacent-level fracture.[25]

As expected, our study proved the advantage of KP in the correction of vertebral deformity associated with VCFs of severe deformity (Table 3). KP is an alternative minimally invasive intervention method for VP that uses an expandable balloon to restore height and create space in the central part of the vertebral body before cement injection.[19] Data from our study showed that KP was performed in a group of patients with severe preoperative deformity and showed significantly better angle recovery rates (Table 3). In our previous study, We confirmed that the frequency of complications decreased when additional pain control was provided through nerve root blocks.[29] Also, considering the impact of sagittal balance on the patient’s long-term pain, gait, quality of life, and risk of falling, KP is considered to be a very useful treatment.[13,15] Evaluation is limited as there have been no studies on the long-term results of pain, radiological and clinical complications, but short-term results showed no significant difference from VP.

This was a retrospective study, so there was a lack of randomization for both groups of patients and a relatively short follow-up period. Although we treated many patients at a single institution for 10 years, we unable to obtain a numerous long-term follow-up patient group. As the long-term outcome after the procedure could not be confirmed, the impact of osteoporosis treatment could not be studied. It is believed that randomized controlled trials with larger sample sizes, multicenter studies, and longer follow-up data are needed to complement the current results and confirm more accurate results.

Considering that KP was performed on fractures with severe deformity, it didn’t make a difference in clinical outcomes and incidence of adjacent vertebral fractures compared to VP and improvements in radiological measurement have been demonstrated. As improvement in kyphotic deformity can impact a prolonged patient’s physical activity and pain, KP may be a good treatment choice for pain improvement and long-term prognosis in high compressive rate vertebral fracture.