Prognostic factors of balloon kyphoplasty for osteoporotic vertebral fractures with diffuse idiopathic skeletal hyperostosis

Yuji Tsuchikawa Department of Orthopaedic Surgery, JA Hiroshima General Hospital, Hatsukaichi, Japan; and

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Naosuke Kamei Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan

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Kiyotaka Yamada Department of Orthopaedic Surgery, JA Hiroshima General Hospital, Hatsukaichi, Japan; and

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Toshio Nakamae Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan

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Nobuo Adachi Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan

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Yoshinori Fujimoto Department of Orthopaedic Surgery, JA Hiroshima General Hospital, Hatsukaichi, Japan; and

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OBJECTIVE

The authors aimed to determine the poor prognostic factors of balloon kyphoplasty for the treatment of fractures of the most distal or distal-adjacent vertebrae in ankylosing spines with diffuse idiopathic skeletal hyperostosis (DISH).

METHODS

Eighty-nine patients with fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with DISH were included and divided into two groups: those with (n = 51) and without (n = 38) bone healing 6 months postoperatively. Clinical evaluation included age, sex, time from onset to surgery, the visual analog scale score for low-back pain, and the Oswestry Disability Index (ODI). The VAS scores and ODI were measured both preoperatively and at 6 months postoperatively. Radiological evaluations included bone density; wedge angles of the fractured vertebrae in the supine and sitting positions on lateral radiographs; differences in the wedge angles (change in wedge angle); and the amount of polymethylmethacrylate used.

RESULTS

The preoperative ODI, vertebral wedge angles in the supine and sitting positions, change in wedge angle, and amount of polymethylmethacrylate were significantly different between the two groups and were significantly associated with delayed bone healing in univariate logistic regression analysis. Multivariate logistic regression analysis showed that only a change in the wedge angle was significantly associated with delayed healing, with a cutoff value of 10°, sensitivity of 84.2%, and specificity of 82.4%.

CONCLUSIONS

Treatment with balloon kyphoplasty alone should be avoided in patients with a difference ≥ 10° in the wedge angle of the fractured vertebrae between the supine and sitting positions.

ABBREVIATIONS

BKP = balloon kyphoplasty; DISH = diffuse idiopathic skeletal hyperostosis; ODI = Oswestry Disability Index; OVF = osteoporotic vertebral fracture; PMMA = polymethylmethacrylate; ROC = receiver operating characteristic; VAS = visual analog scale.

OBJECTIVE

The authors aimed to determine the poor prognostic factors of balloon kyphoplasty for the treatment of fractures of the most distal or distal-adjacent vertebrae in ankylosing spines with diffuse idiopathic skeletal hyperostosis (DISH).

METHODS

Eighty-nine patients with fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with DISH were included and divided into two groups: those with (n = 51) and without (n = 38) bone healing 6 months postoperatively. Clinical evaluation included age, sex, time from onset to surgery, the visual analog scale score for low-back pain, and the Oswestry Disability Index (ODI). The VAS scores and ODI were measured both preoperatively and at 6 months postoperatively. Radiological evaluations included bone density; wedge angles of the fractured vertebrae in the supine and sitting positions on lateral radiographs; differences in the wedge angles (change in wedge angle); and the amount of polymethylmethacrylate used.

RESULTS

The preoperative ODI, vertebral wedge angles in the supine and sitting positions, change in wedge angle, and amount of polymethylmethacrylate were significantly different between the two groups and were significantly associated with delayed bone healing in univariate logistic regression analysis. Multivariate logistic regression analysis showed that only a change in the wedge angle was significantly associated with delayed healing, with a cutoff value of 10°, sensitivity of 84.2%, and specificity of 82.4%.

CONCLUSIONS

Treatment with balloon kyphoplasty alone should be avoided in patients with a difference ≥ 10° in the wedge angle of the fractured vertebrae between the supine and sitting positions.

In Brief

The purpose of this study was to determine the poor prognostic factors of balloon kyphoplasty in the treatment of fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with diffuse idiopathic skeletal hyperplasia. Bone healing was more likely to be delayed in patients with wedge angle changes ≥ 10°. This study demonstrates the indication for balloon kyphoplasty in osteoporotic vertebral fractures in patients with diffuse idiopathic skeletal hyperplasia.

The incidence of osteoporotic vertebral fractures (OVFs) in the elderly is increasing as society ages, impairing the daily activities of the elderly and increasing the economic burden on society.13 Conservative treatment of ordinary OVFs was reported to result in good outcomes;4 however, fractures in the fused part of ankylosing spines with diffuse idiopathic skeletal hyperostosis (DISH) tend to create three columns, which usually have poor clinical outcomes and are indications for surgery.5 Additionally, conservative treatment of vertebral fractures in patients with DISH was reported to have poor outcomes, even in nonfused and type A fractures, which are usually treated conservatively.6

Balloon kyphoplasty (BKP) is a minimally invasive and effective treatment for vertebral fractures, and is widely used for the treatment of OVFs because it provides early pain relief and improves activities of daily living.7,8 We previously demonstrated that intervertebral bridging osteophyte formation adjacent to the cephalic side of a fractured vertebra, as seen in DISH, is a poor prognostic factor for adjacent vertebral fractures and cement loosening following BKP for OVFs.9 However, BKP also resulted in favorable outcomes in some patients with intervertebral bridging osteophytes. Early surgical stabilization is therefore recommended for vertebral fractures in patients with DISH, due to the risk of instability and secondary delayed neurological deterioration.10

Fusion surgery for OVFs in ankylosing spines with DISH has been previously reported;1114 however, minimally invasive treatment is desirable due to the high incidence of postoperative complications reported in patients with DISH.15,16 Although the treatment of ankylosing spinal fractures requires fusion surgery similar to that required for long bone fractures, the indications for BKP in fractures of the terminal or adjacent vertebral bodies of ankylosing spines remain controversial.9,17 Therefore, the purpose of this study was to determine the poor prognostic factors of BKP for the treatment of fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with DISH.

Methods

This retrospective study was approved by the ethics committee of our institution, and informed consent was obtained from all participants.

Participants

BKP was performed in patients with fresh vertebral compression fractures of the thoracic or lumbar spine who had persistent pain ≥ 40 mm on the visual analog scale (VAS) despite conservative treatment with bracing for at least 1 month postinjury, and who preferred surgery with BKP. The BKP procedure was performed using BKP (Kyphon; Medtronic Sofamor Danek). Needles were inserted into the fractured vertebrae through the bilateral pedicles, the balloons were placed through these needles into the vertebrae and dilated, and polymethylmethacrylate (PMMA) was infused through the same needles after the balloons were removed. After the BKP procedure patients wore spinal braces for at least 3 months.

We first evaluated the CT images of 795 patients with single-level OVFs who underwent BKP at our hospital between January 2011 and September 2020. Among them, 150 patients exhibited intervertebral bridging osteophyte formation that met the criteria for DISH, which includes the following: continuous ossification bridges across ≥ 4 vertebrae; maintained disc height; and no osteosclerosis or bone healing at the sacroiliac joints.18 Eighty-nine patients had fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with bridging osteophytes (Fig. 1A and B), and were divided into two groups: patients with (union group; Fig. 1C) and without (nonunion group; Fig. 1D) bone healing 6 months postsurgery. Bone healing was determined when the cephalad and caudal vertebral endplates of the fractured vertebrae achieved fusion, which was confirmed by CT sagittal or coronal sectional views. Fractures of the most distal vertebra or ≥ 1 distal-adjacent vertebrae of an ankylosing spine in which ≥ 4 vertebrae are bridged by continuous ossification were included in this study. Fractures of ankylosing spines at sites other than the most distal vertebrae, or fractures of vertebrae > 2 vertebrae away from ankylosing spines were excluded from this study.

FIG. 1.
FIG. 1.

CT sagittal images of the vertebral fracture site (arrows). A: Vertebral fracture at the most distal end of an ankylosing spine. B: Fracture of the distal-adjacent vertebra of an ankylosing spine. C: Bone fusion at the vertebral fracture site after BKP. D: Delayed bone fusion at the vertebral fracture site after BKP.

Assessments

Back pain was measured using the VAS and the American Academy of Orthopaedic Surgeons MODEMS (Musculoskeletal Outcomes Data Evaluation and Management System) version of the Oswestry Disability Index (ODI; range 0%–100%), evaluated both preoperatively and at 6 months postoperatively.19,20

The bone densities of the lumbar spine and left proximal femur were assessed immediately before surgery using dual-energy x-ray absorptiometry scanning. The bone density of the lumbar spine was evaluated using the mean value of the L2–4 vertebrae, excluding the fractured vertebrae.

Vertebral wedge angles were evaluated from plain lateral radiographic images in the supine (Fig. 2A) and sitting (Fig. 2B) positions immediately before surgery.9 The degree of change in the vertebral wedge angle was assessed as the difference in this angle between the supine and sitting positions on plain lateral radiographic scans, according to a previous study (β° − α° in Fig. 2).9

FIG. 2.
FIG. 2.

Plain lateral radiographic images of a fractured vertebra. Vertebral wedge angle in the supine (panel A, α°) and sitting (panel B, β°) positions. The change in the wedge angle was calculated as the difference between these angles (β° − α°).

Intervertebral bridging osteophyte formation was evaluated via CT scans obtained immediately before surgery. The clinical and radiographic characteristics of the patients immediately before surgery, including age, sex, time from onset to surgery, VAS score, ODI score, bone densities of the left proximal femur and lumbar spine, vertebral wedge angle in the supine and sitting positions, degree of change in the vertebral wedge angle, and amount of PMMA cement infused into fractured vertebrae, were analyzed as possible factors associated with delayed bone healing 6 months after BKP. Data for the amounts of PMMA injected were obtained from surgical records.

Statistical Analyses

Continuous values were expressed as the mean ± SD. Between-group comparisons of continuous and nominal variables were performed using the Mann-Whitney U-test, Fisher’s exact test, or chi-square test, as appropriate. The Wilcoxon signed-rank test was performed to compare the preoperative and postoperative VAS or ODI scores in each group, while univariate and multivariate logistic regression analyses were used to identify the independent factors associated with delayed bone healing. The relationships between continuous variables were evaluated using Pearson’s product-moment correlation coefficients with 95% confidence intervals. Receiver operating characteristic (ROC) curve analysis was used to determine the cutoff values for the degree of change in the vertebral wedge angle that would delay bone healing. Statistical significance was set at p < 0.05, and statistical analyses were performed using JMP 16 software (SAS Institute, Inc.).

Results

Among the 89 patients (42 men, 47 women) with fractures of the most distal or distal-adjacent vertebrae of ankylosing spines, the average age was 80.1 (range 63–94) years. Patients were divided into union (n = 51) and nonunion (n = 38) groups for comparison (Table 1).

TABLE 1.

Comparison of clinical and radiological factors with and without bone fusion

VariableTotal, n = 89Union, n = 51Nonunion, n = 38p Value
Age in yrs80.1 ± 6.9 (63 to 94)79.5 ± 7.4 (63 to 94)81.1 ± 6.3 (68 to 91)0.295
Female sex, no. (%)47 (52.8%)27 (52.9%)20 (52.6%)0.977
Time since onset in mos3.6 ± 4.0 (0.3 to 18)4.1 ± 4.5 (0.3 to 18)3.3 ± 2.0 (0.5 to 7)0.756
Preop VAS score74.5 ± 19.4 (40 to 100)73.4 ± 19.4 (5 to 100)76.0 ± 19.8 (7 to 100)0.549
Postop VAS score38.0 ± 27.6 (0 to 100)*28.8 ± 24.7 (0 to 80)*54.2 ± 25.3 (10 to 100)*<0.001
Preop ODI59.4 ± 18.0 (26.7 to 96.7)54.5 ± 17.5 (26.7 to 95.6)65.9 ± 16.8 (42.2 to 96.7)0.008
Postop ODI38.9 ± 20.5 (0 to 88.9)*32.1 ± 18.0 (0 to 68.9)*50.3 ± 19.7 (14.3 to 88.9)*<0.001
Site of vertebral fracture (no. of cases)T7 (1), T9 (1), T10 (1), T11 (1), T12 (30), L1 (34), L2 (12), L3 (6), L4 (3)T7 (1), T9 (1), T10 (1), T12 (16), L1 (19), L2 (7), L3 (5), L4 (1)T11 (1), T12 (14), L1 (15), L2 (5), L3 (1), L4 (2)0.762
Bone density in proximal femur, YAM %74.9 ± 12.6 (44 to 109)75.7 ± 13.0 (44 to 109)73.8 ± 12.1 (50 to 106)0.450
Bone density in lumbar vertebrae, YAM %81.9 ± 16.0 (50 to 136)80.9 ± 15.8 (50 to 116)83.3 ± 16.4 (59 to 136)0.660
Wedge angle in supine, °12.9 ± 8.1 (−8 to 33)14.6 ± 7.9 (2 to 33)10.6 ± 7.9 (−8 to 27)0.040
Wedge angle in sitting, °22.0 ± 8.2 (2 to 36)20.5 ± 8.4 (5 to 36)24.1 ± 7.6 (2 to 36)0.045
Change of wedge angle, °9.4 ± 5.4 (1 to 23)6.2 ± 3.5 (1 to 17)13.6 ± 4.4 (5 to 23)<0.001
Amount of PMMA in ml4.6 ± 2.3 (1.0 to 11.5)3.6 ± 2.1 (1.0 to 11.5)5.8 ± 2.0 (3.5 to 10.0)<0.001

YAM = young adult mean.

Unless otherwise indicated, values are expressed as the mean ± SD (range). Boldface type indicates statistical significance.

Significantly better than preoperative values (p < 0.05).

Among the clinical factors, there were no significant differences between the two groups regarding age, sex, and time from onset to surgery. Preoperative VAS scores were not significantly different between the two groups; however, preoperative ODI scores were significantly higher in the nonunion than union group. The postoperative VAS and ODI scores were significantly better than the preoperative scores in both groups (all p < 0.001), and both postoperative scores were significantly better in the union than nonunion group.

Regarding radiological assessments, there were no significant differences in the site of vertebral fractures, or bone densities of the proximal femur and lumbar spine, between the two groups. There were significant differences between the two groups in the vertebral wedge angles between the supine and sitting positions (change in wedge angle), and the amount of PMMA infused into the fractured vertebrae. The nonunion group had a smaller vertebral wedge angle in the supine position, and a larger wedge angle in the sitting position than the union group, resulting in a larger change in the wedge angle. The amount of PMMA was greater in the nonunion than in the union group.

Given that the pathophysiology might differ between the most distal and distal-adjacent vertebral fractures, a subanalysis comparing patients with these two types of fractures was performed (Table 2). Significant age differences were observed between the two groups; however, there were no significant differences between the two groups in the bone healing rates or in other factors.

TABLE 2.

Comparison of clinical and radiological factors in fractures of the most distal vertebrae and distal-adjacent vertebrae

VariableDistal, n = 24Adjacent, n = 65p Value
Bone fusion0.716
 Union1338
 Nonunion1127
Age in yrs83.0 ± 6.3 (73 to 94)79.1 ± 6.9 (63 to 93)0.026
Female sex, no. (%)13 (54.2%)34 (52.3%)0.876
Time since onset in mos3.2 ± 1.7 (1.0 to 7.0)3.8 ± 4.0 (0.3 to 18.0)0.738
Preop VAS score76.7 ± 17.2 (40 to 100)73.6 ± 20.3 (5 to 100)0.643
Postop VAS score35.0 ± 26.7 (0 to 80)*41.0 ± 29.1 (0 to 100)*0.496
Preop ODI59.9 ± 17.5 (27.5 to 95.6)59.3 ± 18.4 (26.7 to 96.7)0.794
Postop ODI41.2 ± 18.8 (2.2 to 64.0)*37.7 ± 21.4 (0 to 88.9)*0.420
Site of vertebral fracture (no. of cases)T10 (1), T12 (7), L1 (13), L2 (3)T7 (1), T9 (1), T11 (1), T12 (23), L1 (21), L2 (9), L3 (6), L4 (3)0.365
Bone density in proximal femur, YAM %75.0 ± 15.3 (45 to 109)74.9 ± 11.6 (44 to 98)0.781
Bone density in lumbar vertebrae, YAM %86.8 ± 16.0 (62 to 117)80.2 ± 15.7 (50 to 136)0.660
Wedge angle in supine, °11.2 ± 7.4 (−5 to 23)13.5 ± 8.3 (−8 to 33)0.306
Wedge angle in sitting, °20.8 ± 6.7 (7 to 30)22.5 ± 8.7 (2 to 36)0.236
Change of wedge angle, °9.5 ± 5.9 (1 to 23)9.0 ± 5.6 (1 to 17)0.119
Amount of PMMA in ml4.4 ± 1.3 (2.4 to 6.0)4.7 ± 2.6 (1.0 to 11.5)0.790

Unless otherwise indicated, values are expressed as the mean ± SD (range). Boldface type indicates statistical significance.

Significantly better than preoperative values (p < 0.05).

Univariate logistic regression analysis was performed to identify risk factors associated with delayed bone healing (Table 3). Preoperative ODI scores, vertebral wedge angles in the supine and sitting positions, change in wedge angle, and amount of PMMA were shown to be significantly associated with delayed bone healing. Correlations between these factors were evaluated using Pearson’s product-moment correlations (Table 4). There was no significant correlation between the vertebral wedge angle in the sitting position and preoperative ODI score, or the amount of PMMA; however, all other combinations showed significant correlations.

TABLE 3.

Univariate logistic regression analysis of the relationship of clinical and radiological factors to delayed bone fusion

VariableOR95% CIp Value
Age1.0350.973–1.1040.273
Female sex0.9880.426–2.2910.609
Time since onset0.2710.011–6.4770.420
Preop VAS score1.0070.984–1.0310.555
Preop ODI1.0391.010–1.0680.005
Bone density in proximal femur0.9880.954–1.0220.487
Bone density in lumbar vertebrae1.0090.982–1.0370.502
Wedge angle in supine0.9360.885–0.9910.024
Wedge angle in sitting1.0581.002–1.1180.043
Change in wedge angle1.5751.316–1.884<0.001
Amount of PMMA1.7261.170–2.5450.006

Boldface type indicates statistical significance.

TABLE 4.

Correlations between clinical and radiological factors

Wedge Angle in SupineWedge Angle in SittingChange of Wedge AngleAmount of PMMA
Preop ODI
  Coefficient−0.480−0.2200.3470.434
  p value<0.0010.0560.0020.008
Wedge angle in supine
  Coefficient0.758−0.327−0.341
  p value<0.0010.0020.021
Wedge angle in sitting
  Coefficient0.352−0.304
  p value<0.0010.277
Change of wedge angle
  Coefficient0.441
  p value0.002

Boldface type indicates statistical significance.

Multivariate logistic analysis was performed to further examine the association between these factors and delayed bone healing (Table 5). However, vertebral wedge angles in the supine and sitting positions were excluded from the analysis because they were variables in the formula used to calculate the change in the wedge angle. Multivariate logistic analysis showed that only a change in the wedge angle was significantly associated with delayed bone healing. Additionally, ROC analysis was performed to determine the degree of change in the wedge angle to predict delayed bone healing. ROC analysis showed that the area under the curve was 0.909, with a cutoff value of 10°, a sensitivity of 84.2%, and a specificity of 82.4%.

TABLE 5.

Multivariate logistic regression analysis of the relationship of clinical and radiological factors to delayed bone fusion

VariableOR95% CIp Value
Preop ODI1.0050.940–1.0740.884
Change of wedge angle1.5511.130–2.1300.007
Amount of PMMA1.6140.982–2.6520.059

Boldface type indicates statistical significance.

Discussion

In this study, the clinical and radiological factors associated with delayed bone healing were analyzed in patients who underwent BKP for fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with DISH. Comparison of the presence or absence of bone healing 6 months postoperatively, as well as univariate logistic regression analysis, demonstrated that preoperative ODI scores, vertebral wedge angles in the supine and sitting positions, change in vertebral wedge angle between the supine and sitting positions, and the amount of PMMA injected into the fractured vertebrae were significantly associated with delayed bone healing. Multivariate logistic regression analysis revealed that only a change in the wedge angle was significantly associated with delayed bone healing, and the angular cutoff value for the change in wedge angle to identify delayed bone healing was 10°, with a sensitivity of 84.2% and a specificity of 82.4%.

Patients both with and without bone healing had significantly better postoperative than preoperative VAS and ODI scores; however, postoperative VAS and ODI scores were significantly better in patients with bone healing than in those without. These results suggest that bone healing in fractures contributes to pain reduction and improved activities of daily living. Even in BKP for common OVFs, bone healing at the fracture site was observed in 27/36 vertebrae (75%), contributing to the stabilization of the spine reported in a previous study.21 Still, bone healing did not affect the postoperative VAS score in this previous report. Bone healing after BKP thus seems to be more important for the prognosis of OVFs with DISH than for common OVFs.

An ankylosing spine with DISH poorly distributes axial loads, placing greater stress on the proximal and distal nonfused areas.22 Our previous study showed that intervertebral bridging osteophyte formation on the cephalad side of the fractured vertebra was a risk factor for adjacent vertebral fracture and loosening around the PMMA cement after BKP; however, even among patients with intervertebral bridging osteophytes, 18/32 (56.3%) exhibited no postoperative complications.9 There are also a few previous reports of successful percutaneous vertebroplasties for vertebral fractures in patients with DISH.12,23

The present study showed that fractures of the most distal or distal-adjacent vertebrae of ankylosing spines were stabilized by bone healing in 51/89 patients (57.3%) 6 months after BKP. In addition, fractures of the vertebrae adjacent to the ankylosing spines with disruption of the discs, as shown in Fig. 1B, were stabilized by the appearance of a bony bridge between the fractured vertebra and the adjacent vertebra, as shown in Fig. 1C. These findings suggest that fractures of the most distal or distal-adjacent vertebrae of ankylosing spines can be healed and stabilized by BKP in some patients with DISH. Patients without bone healing had significantly worse preoperative ODI scores, a smaller vertebral wedge angle in the supine position, a larger vertebral wedge angle in the sitting position, a larger change in wedge angle, and a larger amount of PMMA than patients with bone healing. Univariate logistic regression analysis showed a significant association between these factors and bone healing.

Preoperative ODI scores were worse in patients without than with healing, independent of the pain scores. Additionally, whereas these scores did not significantly correlate with the vertebral wedge angle in the sitting position, they did correlate with the vertebral wedge angle in the supine position and with the change in wedge angle. The poor preoperative ODI scores observed in patients without bone healing may be due to instability of the fracture site, independent of pain or spinal alignment. The amount of PMMA is also considered a candidate factor related to bone healing, given that insufficient PMMA infusion into the vertebrae may adversely affect bone healing. However, the amount of PMMA was significantly higher in patients without than in those with bone healing, suggesting that insufficient PMMA volume was not the reason for the inhibition of bone healing. Additionally, the amount of PMMA negatively correlated with the vertebral wedge angle in the supine position, and positively correlated with the change in the wedge angle. The amount of PMMA may thus have increased when the instability of the fractured vertebra was substantial, and a large cavity was created in the vertebral body.

Multivariate logistic regression analysis showed that only a change in the wedge angle was significantly associated with bone healing, suggesting that preoperative instability of fractured vertebrae has the greatest influence on postoperative bone healing. In our previous study, preoperative changes in the vertebral wedge angle tended to be greater in patients with loosening around the PMMA after BKP for OVFs; however, this could not be statistically evaluated because only 3 patients demonstrated loosening around the PMMA.9 In the present study, the cutoff value for the change in wedge angle for delayed bone healing in ROC analysis was 10°. In a previous study on thoracolumbar OVFs, the stability of a fractured vertebra was evaluated via the difference in the wedge angle of the vertebra by using lateral radiographs measured in flexion and extension; here, a value > 11° was identified as dynamic instability, and fusion surgery was recommended instead of kyphoplasty.24 Although the measurement method differed from ours and the rationale for selecting 11° was not provided, their results were similar to those observed in our study. This suggests that surgical treatment with BKP alone should be avoided in patients with preoperative vertebral wedge angle changes ≥ 10°.

This study had some limitations. First, spinal global alignment was not evaluated because some patients were unable to undergo preoperative plain radiography in the standing position. Second, preexisting medical conditions and medications could not be evaluated as candidate factors affecting bone healing, because they typically vary between patients; however, this study did not include patients using steroids or teriparatide, which have a known impact on bone healing. Third, MRI was not used for evaluation in this study because it was not performed in all patients. Fourth, the relationship between the number of intervertebral bridges and postoperative bone healing could not be evaluated because some patients did not have a complete count of the number of intervertebral bridges. Last, comparisons with patients who underwent fusion surgery were not performed because the indications for surgery were different. Of the patients without bone healing after BKP, 3 underwent further spinal fusion surgery.

Conclusions

The factors affecting bone healing at the fracture site after BKP were analyzed in patients with fractures of the most distal or distal-adjacent vertebrae of ankylosing spines with DISH, and preoperative instability was found to have the greatest influence on postoperative bone healing at the fracture site. The cutoff value for the difference in the vertebral wedge angle between the sitting and supine positions that predicted delayed bone healing after BKP was 10°. At the very least, surgical treatment with BKP alone should be avoided, and fusion surgery should be considered for patients with preoperative vertebral wedge angle changes ≥ 10°.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Kamei, Tsuchikawa. Acquisition of data: Yamada. Analysis and interpretation of data: Kamei, Tsuchikawa. Drafting the article: Kamei. Critically revising the article: Tsuchikawa. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Kamei. Statistical analysis: Kamei. Study supervision: Adachi, Fujimoto.

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    Ikuma H, Takao S, Inoue Y, Hirose T, Matsukawa K, Kawasaki K. Treatment of thoracolumbar spinal fracture accompanied by diffuse idiopathic skeletal hyperostosis using transdiscal screws for diffuse idiopathic skeletal hyperostosis: preliminary results. Asian Spine J. 2021;15(3):340348.

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    McCarty S, Bruckner JJ, Camacho JE, et al. Comparison of outcomes in percutaneous fixation of traumatic fractures between ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis. Global Spine J. Published online October 20, 2021. doi:10.1177/21925682211052003

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    Lakomkin N, Mikula AL, Pinter ZW, et al. Perioperative risk stratification of spine trauma patients with ankylosing spinal disorders: a comparison of 3 quantitative indices. J Neurosurg Spine. 2022;37(5):722728.

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    Liu H, Zhou Q, Zhang J, et al. Kyphoplasty for thoracic and lumbar fractures with an intravertebral vacuum phenomenon in ankylosing spondylitis patients. Front Surg. 2022;9:962723.

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    Resnick D, Shaul SR, Robins JM. Diffuse idiopathic skeletal hyperostosis (DISH): Forestier’s disease with extraspinal manifestations. Radiology. 1975;115(3):513524.

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    Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy. 1980;66(8):271273.

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    Shah NG, Keraliya A, Nunez DB, et al. Injuries to the rigid spine: what the spine surgeon wants to know. Radiographics. 2019;39(2):449466.

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    Kim GD, Chae SU, Kim YJ, Choi DH. Osteoporotic lumbar compression fracture in patient with ankylosing spondylitis treated with kyphoplasty. J Bone Metab. 2013;20(1):4750.

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    Hao DJ, Yang JS, Tuo Y, et al. Reliability and application of the new morphological classification system for chronic symptomatic osteoporotic thoracolumbar fracture. J Orthop Surg Res. 2020;15(1):348.

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    • Export Citation
  • Collapse
  • Expand
Figure from Vedantam et al. (pp 28–39).
  • FIG. 1.

    CT sagittal images of the vertebral fracture site (arrows). A: Vertebral fracture at the most distal end of an ankylosing spine. B: Fracture of the distal-adjacent vertebra of an ankylosing spine. C: Bone fusion at the vertebral fracture site after BKP. D: Delayed bone fusion at the vertebral fracture site after BKP.

  • FIG. 2.

    Plain lateral radiographic images of a fractured vertebra. Vertebral wedge angle in the supine (panel A, α°) and sitting (panel B, β°) positions. The change in the wedge angle was calculated as the difference between these angles (β° − α°).

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    Jindal V, Binyala S, Kohli SS. Balloon kyphoplasty versus percutaneous vertebroplasty for osteoporotic vertebral body compression fractures: clinical and radiological outcomes. Spine J. Published online December 4, 2022. doi:10.1016/j.spinee.2022.11.015

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    Wang S, Zheng L, Ma JX, et al. Analysis of the most influential publications on vertebral augmentation for treating osteoporotic vertebral compression fracture: a review. Medicine (Baltimore). 2022;101(31):e30023.

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    Kamei N, Yamada K, Nakamae T, et al. Radiographic factors for adjacent vertebral fractures and cement loosening following balloon kyphoplasty in patients with osteoporotic vertebral fractures. Spine Surg Relat Res. 2021;6(2):159166.

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    Okada E, Tsuji T, Shimizu K, et al. CT-based morphological analysis of spinal fractures in patients with diffuse idiopathic skeletal hyperostosis. J Orthop Sci. 2017;22(1):39.

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    Shiraishi D, Yamamoto Y, Motonori I, et al. Downward penetrating endplate screw technique under O-arm navigation posterior fusion in patients with osteoporotic vertebral body fractures associated with diffuse idiopathic skeletal hyperostosis. Surg Neurol Int. 2022;13:436.

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  • 12

    Wang W, Huang Y, Zhang L, Yang H. Percutaneous kyphoplasty for the treatment of diffuse idiopathic skeletal hyperostosis with vertebral fractures: a case report and treatment review. Front Surg. 2022;9:922139.

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  • 13

    Hishiya T, Ishikawa T, Ota M. Posterior spinal fixation using penetrating endplate screws in patients with diffuse idiopathic skeletal hyperostosis-related thoracolumbar fractures. J Neurosurg Spine. 2021;34(6):936941.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Ikuma H, Takao S, Inoue Y, Hirose T, Matsukawa K, Kawasaki K. Treatment of thoracolumbar spinal fracture accompanied by diffuse idiopathic skeletal hyperostosis using transdiscal screws for diffuse idiopathic skeletal hyperostosis: preliminary results. Asian Spine J. 2021;15(3):340348.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 15

    McCarty S, Bruckner JJ, Camacho JE, et al. Comparison of outcomes in percutaneous fixation of traumatic fractures between ankylosing spondylitis and diffuse idiopathic skeletal hyperostosis. Global Spine J. Published online October 20, 2021. doi:10.1177/21925682211052003

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 16

    Lakomkin N, Mikula AL, Pinter ZW, et al. Perioperative risk stratification of spine trauma patients with ankylosing spinal disorders: a comparison of 3 quantitative indices. J Neurosurg Spine. 2022;37(5):722728.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 17

    Liu H, Zhou Q, Zhang J, et al. Kyphoplasty for thoracic and lumbar fractures with an intravertebral vacuum phenomenon in ankylosing spondylitis patients. Front Surg. 2022;9:962723.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Resnick D, Shaul SR, Robins JM. Diffuse idiopathic skeletal hyperostosis (DISH): Forestier’s disease with extraspinal manifestations. Radiology. 1975;115(3):513524.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 19

    Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy. 1980;66(8):271273.

  • 20

    Fairbank JC, Pynsent PB. The Oswestry Disability Index. Spine (Phila Pa 1976). 2000;25(22):29402952.

  • 21

    Tarukado K, Tono O, Harimaya K, Doi T. Does an osteoporotic vertebral fracture treated by balloon kyphoplasty successfully achieve bone union during the follow-up? A retrospective study with a minimum 2-year follow-up. J Orthop. 2017;14(4):480483.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 22

    Shah NG, Keraliya A, Nunez DB, et al. Injuries to the rigid spine: what the spine surgeon wants to know. Radiographics. 2019;39(2):449466.

  • 23

    Kim GD, Chae SU, Kim YJ, Choi DH. Osteoporotic lumbar compression fracture in patient with ankylosing spondylitis treated with kyphoplasty. J Bone Metab. 2013;20(1):4750.

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 24

    Hao DJ, Yang JS, Tuo Y, et al. Reliability and application of the new morphological classification system for chronic symptomatic osteoporotic thoracolumbar fracture. J Orthop Surg Res. 2020;15(1):348.

    • PubMed
    • Search Google Scholar
    • Export Citation

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