Outcome of percutaneous balloon kyphoplasty in vertebral compression fractures

Safety and Efficacy of Balloon Kyphoplasty for Vertebral Fractures With Posterior Wall Disruption

BACKGROUND

Percutaneous balloon kyphoplasty (BK) is widely accepted as both a safe and effective method for the treatment of symptomatic benign vertebral compression fractures (VCFs) of the thoracic and lumbar spines. A disruption in the posterior wall of the affected vertebra is often considered to be a relative or an absolute contraindication to BK. This study was performed to determine the safety as well as the efficacy of BK for vertebral body compression fractures associated with posterior wall disruption.

METHODS

This was a retrospective, nonrandomized clinical cohort investigation of patients with VCF and posterior wall disruption treated with BK between 2010 and 2018. All cases were performed using a bipedicular technique. Each case was examined for cement leakage, anterior vertebral body height restoration, improvement in pain (determined by VAS) from baseline and 6-week postprocedure, and clinical sequelae from cement leakage.

RESULTS

Ninety-eight consecutive patients with 157 VCF levels who underwent BK were evaluated. There was a significant improvement in anterior vertebral height, vertebral wedge angle, and local kyphotic angle in all cases. The mean preoperative VAS improved from 8.7 preprocedure to 2.5 postprocedure (P = .001). There were 14 (9%) cases with asymptomatic cement leakage outside of the vertebral body, and no patients experienced postprocedure neurological symptoms at the 6-week follow up.

CONCLUSIONS

BK in the setting of posterior wall disruption was found to be a safe and highly effective treatment for patients with benign compression fractures. Posterior wall disruption should not be considered an absolute contraindication to BK.

Percutaneous intervertebral bridging cementoplasty for adjacent multilevel osteoporotic thoracolumbar fractures with vertebral endplate-disc complex injury: technical note

This paper describes a minimally invasive technique of percutaneous intervertebral bridging cementoplasty (PIBC) to augment the fractured vertebrae and immobilize the intervertebral space with endplate-disc complex injury simultaneously. Thirty-two patients with adjacent multilevel osteoporotic thoracolumbar fractures (AMOTLFs) and vertebral endplate-disc complex injury (EDCI) treated by PIBC were retrospectively reviewed. The PIBC technique was a combination of puncture, balloon expansion and bridging cementoplasty. The clinical and radiological assessments were reviewed. The operation time was 82.8 ± 32.5 min, and blood loss was 76.9 ± 31.7 mL. A cement bridge was connected between the two fractured vertebrae across the injured intervertebral space. VAS at three time points including pre-operation, post-operation 1 day and final follow-up was 6.9 ± 0.9, 2.9 ± 0.8 and 1.7 ± 0.8, respectively; ODI at three time points was (71.1 ± 7.8)%, (18.4 ± 5.7)%, and (10.3 ± 5.7)%, respectively; Cobb angle at three time points was 46.0° ± 10.4°, 25.9° ± 8.5°, and 27.5° ± 7.1°, respectively. Compared with pre-operation, VAS, ODI and Cobb angle were significantly improved at post-operation 1 day and final follow-up (P < 0.05). Clinical asymptomatic cement leakage was observed in thirteen patients. No vessel or neurological injury was observed. PIBC may be an alternative way of treatment for AMOTLFs with EDCI. The technique is a minimally invasive surgery to augment the fractured vertebrae and immobilize the injured intervertebral space simultaneously.

Percutaneous balloon kyphoplasty in the treatment of vertebral compression fractures: a single-center analysis of pain and quality of life outcomes

BACKGROUND

Vertebral body compression fractures are one of the most common causes of disability and morbidity, especially among the elderly population. The present study was performed in order to evaluate the effect of percutaneous balloon kyphoplasty (BKP) on patients' pain and quality of life (QOL) in Iran.

METHODS

The study was conducted on a consecutive series of 54 patients with symptomatic vertebral compression fractures who failed conservative management between 2014 and 2017. A quasi-experimental design was employed in which the pain severity, quality of life, and kyphotic angle were measured before and 3 and 12 months after the PBK procedure. Pain and quality of life outcomes were determined using a Visual Analogue Scale (VAS) for Pain and the 12-Item Short Form Health Survey (SF-12) for QOL.

RESULTS

Excellent improvement in VAS was documented at 3 and 12 months after the BKP procedure (p = 0.001). Improvement at 3 months was maintained through the 12 months follow-up period. A statistically significant improvement in QOL was documented at 3 months after BKP that continued to improve through 12 months follow-up. The mean kyphotic angle before PBK was 19.4 ± 5.3 degrees which after 3 months improved to 12.8 ± 3.1 degrees; this reduction was significant (p < 0.001). No new fractures occurred during the follow-up period.

CONCLUSION

Balloon kyphoplasty was determined to be a safe and successful method for treating symptomatic vertebral compression fractures. It leads to significant pain relief, an improvement in self-reported QOL measures, and correction in kyphotic deformity.

Osteoporotic Vertebral Compression Fracture and Single Balloon Extrapedicular Kyphoplasty: Findings and Technical Considerations

Objective:

To evaluate the functional and radiological outcome of balloon kyphoplasty and to endorse the unilateral single balloon extrapedicular kyphoplasty as practically more feasible and safer method in comparison to the conventional methods.

Methods:

Totally, 81 patients were presented to our center with osteoporotic vertebral compression fracture. Among these, 59 patients (61 vertebrae) were enrolled with stable wedge osteoporotic compression fracture. Pre-operatively percentage of vertebral height loss and kyphotic angle were calculated and single balloon extrapedicular kyphoplasty was performed in all cases.

Results:

Postoperatively, anterior vertebral height improved to 79.61% of normal subjects. In our study, the mean segmental kyphosis correction following balloon kyphoplasty was 14.27°. Overall incidence of cement leak in our study was 15.25%.

Conclusion:

Although we encountered the few difficulties, but this technique holds the safety and feasibility measures. Furthermore, it is effective in restoring anterior vertebral height, alignment and angle of kyphosis.

[Effect of percutaneous kyphoplasty on lumbar-pelvic correlation in osteoporotic vertebral compressive fractures]

OBJECTIVE

To explore the effect of percutaneous kyphoplasty (PKP) on lumbar-pelvic correlation in osteoporotic vertebral compressive fracture (OVCF).

METHODS

According to the inclusion criteria, 63 patients with primary osteoporosis between January 2012 and June 2017 were selected as the control group and 67 patients with single-segment lumbar OVCF receiving PKP and complete clinical data were included as the observation group. There was no significant difference in gender, age, and lumbar spine bone density between the two groups ( P>0.05). The visual analogue scale (VAS) score and Oswestry Disability Index (ODI) score were used to assess lumbar pain and function before operation and at 3 days after operation in the observation group; lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) were measured in lumbar lateral X-ray films which were taken before PKP and at 1 month after PKP. The same parameters were measured in the lumbar lateral X-ray films which were taken at the time of initial diagnosis in the control group.

RESULTS

All patients were followed up 3-24 months with an average of 5.8 months in the observation group. The VAS score decreased from 5.6±1.8 before PKP to 2.8±1.3 at 3 days after PKP ( t=14.082, P=0.000); ODI decreased from 50.1%±5.0% before PKP to 18.2%±1.8% ( t=47.011, P=0.000). Compared with the control group, the LL, PI, and SS decreased and the PT increased in the observation group, and only the difference in LL between the two groups was significant ( P<0.05). In the observation group, the LL and SS significantly increased ( P<0.05) and PT significantly decreased ( P<0.05) at 1 month after operation when compared with preoperative ones, and PI decreased, but the difference was not significant ( P>0.05). In the control group, LL was positively correlated with PI and SS ( P<0.05); PI was positively correlated with PT and SS ( P<0.05). In the observation group, PI was positively correlated with SS ( P<0.05) before and after PKP.

CONCLUSION

OVCF patients lost the specific lumbar-pelvic correlation. PKP can restore lumbar lordosis, but it still can not restore the normal physiological fitting.

A prospective, international, randomized, noninferiority study comparing an implantable titanium vertebral augmentation device versus balloon kyphoplasty in the reduction of vertebral compression fractures (SAKOS study)

BACKGROUND CONTEXT

Balloon kyphoplasty (BKP) is a commonly performed vertebral augmentation procedure for painful osteoporotic vertebral compression fractures (OVCFs).

OBJECTIVE

This study aimed to support a non-inferiority finding for the use of a titanium implantable vertebral augmentation device (TIVAD) compared to BKP.

STUDY DESIGN

Prospective, parallel group, controlled comparative randomized study.

PATIENT SAMPLE

Patients who presented with one or two painful OVCFs located between T7 and L4 aged <3 months, failed conservative treatment, and had an Oswestry Disability Index (ODI) score ≥30/100 were eligible for the study.

OUTCOME MEASURES

The primary composite endpoint was defined as: reduction in VCF fracture-related pain at 12 months from baseline and maintenance or functional improvement (ODI) at 12 months from baseline, and absence of device-related adverse event or surgical reintervention. If the primary composite endpoint was successful, a fourth component (absence of adjacent level fracture) was added for analysis. If the analysis of this additional composite endpoint was successful, then midline target height restoration at 6 and 12 months was assessed. Secondary clinical outcomes included back pain intensity, ODI score, EQ-5D index score (range 0=death to 1=full health) and EQ-VAS score (range 0-100).

METHODS

Patients were recruited in 13 hospitals across 5 countries and were randomly assigned (1:1) to either TIVAD or BKP with electronic randomization as described in the protocol. A total of 152 patients with OVCFs were initially randomized. Eleven patients were excluded (six met exclusion criteria, one with evidence of tumor, and four patients had T score out of requested range). Anterior vertebral body height ratio, midline vertebral body height ratio, and Cobb angle were measured preoperatively and postoperatively by an independent imaging core lab. Adjacent and subsequent fractures and safety parameters were recorded throughout the study. Cement extravasation was evaluated on X-rays. All patients were followed at screening at 5 days, 1 month, 6 months, and 12 months postoperatively. This study was supported by Vexim SA. Seven authors received study-specific support less than $10,000 per year and seven authors received no study-specific support.

RESULTS

Among the 141 patients (78.7% female, mean age 73.3±9.5 years) who underwent surgery (TIVAD=68; BKP=73), 126 patients (89.4%) completed the 12-month follow-up period (TIVAD=61; BKP=65). The analysis of primary endpoint on the ITT population demonstrated non-inferiority of the TIVAD to BKP. The analysis of the additional composite endpoint demonstrated the superiority of TIVAD over BKP (p<0.0001) at 6 months (88.1% vs. 60.9%) and at 12 months (79.7% vs. 59.3%). Midline VB height restoration was more improved for TIVAD than for BKP at 6 months (1.14±2.61 mm vs. 0.31±2.22 mm); p=0.0246) and 12 months after surgery (1.31±2.58 mm vs. 0.10±2.34 mm; p=0.0035). No statistically significant differences were shown between procedures for improvement in functional capacity and quality of life. Pain relief was significantly more marked in the TIVAD group compared to the BKP group at 1 month (p=0.029) and at 6 months (p=0.021) after surgery. No patient required surgical reintervention or retreatment at the treated level. No symptomatic cement leakage was reported. Adverse events were similar for both groups (41.2% in the TIVAD group and 45.2% in the BKP group). The incidence of adjacent fractures was significantly lower after the TIVAD procedure than after BKP (12.9% vs. 27.3%; p=0.043).

CONCLUSIONS

Study results demonstrated non-inferiority of the TIVAD to the predicate BKP with an excellent risk/benefit profile for results up to 12 months.

Influence of vertebral bone mineral density on total dispersion volume of bone cement in vertebroplasty

The aim of this study was to investigate the influence of vertebral bone mineral density (BMD) on total diffusion volume of bone cement in percutaneous vertebroplasty (PVP). This study was a retrospective review of prospectively collected data of consecutive patients with A1.2 thoracolumbar compression fractures treated by PVP. Vertebral BMD was measured before surgery and participants were divided into 3 groups according to World Health Organization diagnostic criteria for osteoporosis: Group A (normal BMD), Group B (reduced BMD), and Group C (osteoporosis). All vertebrae were injected with 3 mL of bone cement via the unilateral pedicle and scanned by computed tomography after surgery. Actual injection volume (bone cement only) and total diffusion volume (bone cement plus trabeculae and space) were calculated. Pain severity was determined by the visual analog scale before surgery and at both 1 day and 1 month after surgery. There were no significant differences in injection volume among the groups (P > .05), but the total dispersion volume was greater than injection volume in all groups (P < .05). Pairwise comparison showed a significant difference in total diffusion volume of bone cement between groups, with Group A having the largest volume and Group C the smallest volume. Pain was significantly reduced 1 day after surgery in each group compared with before surgery, but there were no significant between-group differences at 1 day or 1 month. Increasing vertebral BMD was positively correlated with increasing total diffusion volume. BMD does not significantly affect pain relief, despite producing a significantly lower distribution volume in osteoporotic patients.

Kyphoplasty for osteoporotic vertebral fractures with posterior wall injury

BACKGROUND CONTEXT

Cement augmentation techniques are standard treatments for osteoporotic vertebral fractures. Compared with vertebroplasty, kyphoplasty is associated with lower rates of cement leak and better deformity correction; however, posterior wall fractures are relative, but not absolute; contraindications for both techniques and hence treatment practices vary among spine centers.

PURPOSE

The primary aim of this study was to assess our center's incidence of posterior cement leakage in osteoporotic vertebral fractures with posterior wall injury treated by balloon kyphoplasty (BKP). Secondarily, physiological results, pain relief, complication rates, and non-posterior cement leakage were also evaluated.

STUDY DESIGN

This is a prospective cohort study done in a high-volume spine center in Germany.

PATIENT SAMPLE

Eighty-two patients with 98 osteoporotic vertebral fractures with posterior wall cortical injury were studied from 2012 to 2016.

OUTCOME MEASURES

The following were the outcome measures: (1) physiological measures: standing plain x-rays (anteroposterior and lateral views), with the following parameters evaluated: cement leak behind the posterior vertebral body border, Cobb angle for local sagittal deformity, vertebral wedge angle, and anterior vertebral height; (2) cement volume injected in each vertebra; and (3) self-report measures: visual analog scale (VAS).

METHODS

All patients underwent BKP using a bipedicular approach. Preoperative clinical and neurologic evaluations were done. Radiological evaluations included plain X-ray images, computed tomography scans and magnetic resonance imaging. The average follow-up period was 18 months.

RESULTS

No cement leakage into the spinal canal occurred in any of the patients. Asymptomatic leakage into other sites was seen in 22 vertebrae (22.45%). There was significant improvement in the Cobb angle, the vertebral wedge angle, and the anterior vertebral height in all cases. The mean preoperative VAS was 8.1, and this improved to 2.3 on the third postoperative day.

CONCLUSION

Balloon kyphoplasty is a viable option for the treatment of osteoporotic vertebral fractures even with posterior wall involvement.

Bone cement distribution is a potential predictor to the reconstructive effects of unilateral percutaneous kyphoplasty in OVCFs: a retrospective study

Background

Osteoporotic vertebral compression fracture (OVCF) is a common type of fracture, and percutaneous kyphoplasty (PKP) is an eligible solution to it. Previous studies have revealed that both the volume and filling pattern of bone cement correlate with the clinical outcomes after PKP procedure. However, the role of bone cement distribution remains to be illustrated.

Methods

To retrospectively evaluate the relationship between the bone cement distribution and the clinical outcomes of unilateral PKP, we enrolled 73 OVCF patients receiving unilateral PKP treatment. All the intervened vertebrae were classified into three groups based on the bone cement distribution observed on postoperative X-ray films. Preoperative and postoperative radiographic parameters including the vertebral height and kyphotic Cobb angle were recorded, and anterior vertebral height restoration rate (AVHRR) and Cobb angle correction (CR) were then calculated to assess the vertebral height reconstruction. Preoperative and postoperative Oswestry Disability Index (ODI) and visual analogue scale (VAS) were adopted by interviewing patients to assess the mobility improvement and pain relief. Demographic data, body mass index (BMI), lumbar bone mineral density (evaluated by BMD T-score) of each patient, bone cement volume (BV), and bone cement extravasation (BE) were also recorded. Between- and within-group comparisons and multivariable correlation analysis were carried out to analyze the data.

Results

VAS and ODI scores were both significantly improved in all of the enrolled cases with no significant differences between groups. Among the three groups, the average age, AVHRR, and BV were significantly different. Occurrence of BE was significantly different between two of the three groups. AVHRR was demonstrated to correlate negatively with preoperative anterior vertebral height ratio and positively with preoperative Cobb angle, CR, diffusion score, and ODI changes.

Conclusions

Bone cement distribution is a potential predictor to the reconstructive effects in unilateral PKP for OVCFs. Bone cement distribution is associated with AVHRR and BV, as well as the risk of BE occurrence. Greater bone cement distribution may indicate better vertebral restoration along with a higher BE risk.

Percutaneous kyphoplasty combined with zoledronic acid infusion in the treatment of osteoporotic thoracolumbar fractures in the elderly

Objective

We studied the efficacy of zoledronic acid (ZOL) infusion on radiographic and clinical outcomes after percutaneous kyphoplasty (PKP) for elderly patients with osteoporotic thoracolumbar fractures (osteoporotic vertebral compression fractures [OVCFs]).

Materials and methods

We retrospectively analyzed 95 elderly patients (age >65 years) with OVCF. All patients were followed up for 2 years. Thirty-two patients were treated with only once-yearly 5 mg ZOL infusion (ZOL group), 34 patients with only PKP (PKP group) and 29 patients received ZOL infusion 3 days after PKP (PKP+ZOL group).

Results

There were no significant differences in the patients’ age, gender, body mass index, lumbar spine bone mineral density T-scores, baseline of Visual Analog Scale scores and Oswestry Disability Index scores (P>0.05). The postoperative vertebral heights of patients with OVCF after PKP and PKP+ZOL were 23.70±3.03 and 24.30±3.13 mm, respectively, which were significantly higher than that of patients in ZOL group (P<0.05). The reduction in degrees of kyphotic deformity in the PKP and PKP+ZOL groups were corrected to 8.4° and 8.7°. The bone mineral density T-scores of patients with OVCF in the ZOL group and PKP+ZOL group were significantly higher than that in the PKP group (P<0.05). The Visual Analog Scale and the Oswestry Disability Index scores of the PKP+ZOL and PKP groups were significantly lower than those of the ZOL group (P<0.05). The incidence of recompression vertebral fracture (RVF) in the PKP group was 14.7%, but there was no patient with RVF in the PKP+ZOL group (P<0.05).

Conclusion

Once-yearly 5 mg ZOL infusion combined with PKP could provide beneficial effects in elderly osteoporotic patients with OVCF.

Percutaneous Balloon Kyphoplasty Vertebral Augmentation for Compression Fracture Due to Vertebral Metastasis: A 12-Month Retrospective Clinical Study in 72 Patients

Background

Vertebral compression fracture is common in osteoporosis, but can also occur due to bone metastases, for which current treatment options are limited and include bone-strengthening with cement and supportive care. Kyphoplasty is a surgical method of bone augmentation that can reduce pain, stabilize vertebral bone, and restore some or all of the vertebral body height. The aim of this study was to investigate the clinical results of balloon kyphoplasty in the correction of vertebral deformity due to metastatic vertebral compression fracture.

Material/Methods

A retrospective clinical study included 72 patients (82 vertebral bodies) with metastases resulting in vertebral compression fracture, treated by percutaneous balloon kyphoplasty; 9 patients were found incidentally to have vertebral metastases. Bone mineral density (BMD) levels were measured. Patient responses from questionnaires, including the visual analog scale (VAS) for pain intensity, and the Oswestry Disability Index (ODI) for disability, were scored. The local kyphosis angle (KA) and the vertebral height ratio (VHR) were measured. All patients were followed up for 12 months. The initial postoperative and 12-month postoperative values, and the preoperative and postoperative values were compared.

Results

Following balloon kyphoplasty, the KA, VHR, VAS, and ODI scores significantly improved at the final 12-month follow-up compared with preoperative levels (p<0.05, and p<0.001). There was cement leakage in 6 procedures (8.3%) and adjacent segment fracture in 11 procedures (15.2%).

Conclusions

Balloon kyphoplasty was an effective method to reduce pain, reduce disability, and improve quality of life by eliminating kyphotic deformity in pathological vertebral compression fractures due to vertebral metastases.

Clinical outcomes of percutaneous vertebroplasty for selective single segment dorsolumbar vertebral compression fractures

OVERVIEW OF LITERATURE

Elderly patients sustaining a trivial fall may develop vertebral compression fractures if they are predisposed to any factor that leads to decreased bone mineral density. Such patients suffer with severe pain and disability during the early healing stages. Percutaneous Vertebroplasty is mainly done to provide immediate pain relief and also believed to offer stability to the compressed vertebra by preventing further collapse.

METHODS

Selected patients [n = 20; Age = 57.9 ± 7.9 years] with osteoporotic vertebral compression fracture of a single dorsolumbar vertebra were treated with percutaneous vertebroplasty after 2-3 weeks of conservative trail. Their Pain score was noted using numeric rating scale (NRS) before and after the procedure. Functional outcomes were analysed using Roland Morris Disability Questionnaire (RMDQ) score.

RESULTS

NRS pain score before procedure was 8.3 ± 0.6. RMDQ score before procedure was 21.6 ± 0.5. Third post procedural day NRS pain score was 4.7 ± 1.2 (p < 0.0001), denoting significant decrease in pain. Functional outcome analysis using RMDQ score showed an average of 87 ± 6.1 percent improvement (p < 0.0001), by 6 weeks following procedure. Considering pre-injury status all patients were in their best possible functional state by 6 weeks.

CONCLUSIONS

Percutaneous Vertebroplasty serves its purpose adequately and economically. Under controlled circumstances, it offers immediate pain relief and stability, leading to early recovery in selective patients. Yet, underlying poor bone mineral density status needs to be treated.

STUDY DESIGN

Observational Case Series (Level 4).

Cause Analysis of Open Surgery Used After Percutaneous Vertebroplasty and Kyphoplasty

BACKGROUND The aim of this study was to analyze reasons why open surgery was done after percutaneous vertebroplasty and kyphoplasty. MATERIAL AND METHODS Patients (587 vertebral bodies) treated with percutaneous vertebroplasty or kyphoplasty in the Xi'an Honghui Hospital of Shanxi Province from January 2008 to January 2012 were retrospectively analyzed and 13 patients were enrolled in the study. These 13 patients had serious adverse events after percutaneous vertebroplasty or kyphoplasty. Their average age was 64.5 years old. Nine patients had spinal cord injury and 4 had nerve root injury. All the patients underwent open surgery within 4-12 h after definitive diagnosis. RESULTS All 13 cases were followed up (average time 14.1 months, range 3-47 months). Reasons for open surgery included cement extravasation (6 cases, 46.2%), puncture mistake (3 cases, 23.1%), and false selection of indications (4 cases, 30.8%). At last follow-up, skin feeling was better than that before open surgery in 4 cases with nerve root injury, and muscle strength recovered to grade 5 (3 cases) and grade 4 (1 case). In 9 cases with spinal cord injury, 7 patients improved and 2 remained at the same ASIA level. CONCLUSIONS The main reasons for open surgery after percutaneous vertebroplasty and kyphoplasty were cement extravasation (the most common reason), puncture mistake, and false selection of indications.

Tuberculous Spondylitis Following Kyphoplasty: A Case Report and Review of the Literature

Tuberculous spondylitis of the augmented vertebral column following percutaneous vertebroplasty or kyphoplasty has rarely been described. We report an unusual case of tuberculous spondylitis diagnosed after percutaneous kyphoplasty (PKP). A 61-year-old woman presented to our institution complaining of back pain following a fall 7 days before. Radiologic studies revealed an acute osteoporotic compression L1 fracture. The patient denied history of pulmonary tuberculosis (TB) and there were no signs of infection. The patient was discharged from hospital 4 days after undergoing L1 PKP with a dramatic improvement in her back pain. Two years later, the patient was readmitted with a 1 year history of recurrent back pain. Imaging examinations demonstrated long segmental bony destruction involving L1 vertebra with massive paravertebral abscess formation. The tentative diagnosis of tuberculous spondylitis was made, after a serum T-SPOT. The TB test was found to be positive. Anterior debridement, L1 corpectomy, decompression, and autologous rib graft interposition, and posterior T8-L4 instrumentation were performed. The histologic examination of the resected tissue results confirmed the diagnosis of spinal TB. Anti-TB medications were administered for 12 months and the patient recovered without sequelae. Spinal TB and osteoporotic vertebral compression fractures are similar clinically and radiologically. Spinal surgeons should consider this disease entity to avoid misdiagnosis or complications. Early surgical intervention and anti-TB treatment should be instituted as soon as the diagnosis of spinal TB after vertebral augmentation is made.