Role of the supine lateral radiograph of the spine in vertebroplasty for osteoporotic vertebral compression fracture: a prospective study

Abstract

Background: Severely collapsed vertebral compression fracture (VCF) is usually considered as a contraindication for vertebroplasty because of critically decreased vertebral height (less than one-third the original height). However, osteoporotic VCF can possess dynamic mobility with intravertebral cleft (IVC), which can be demonstrated on supine lateral radiographs (SuLR) and standing lateral radiographs (StLR). The purposes of this study were to: (1) evaluate the efficacy of SuLR to detect IVCs and assess the intravertebral mobility in VCFs, and (2) evaluate the short-term results of vertebroplasty in severely collapsed VCFs with IVCs.

Methods: We enrolled 37 patients with 40 symptomatic osteoporotic VCFs for vertebroplasty; 11 had severely collapsed VCFs with concurrent IVCs detected on the SuLR, the others had not-severely collapsed VCFs. A preoperative StLR, SuLR, magnetic resonance imaging (MRI), and postoperative StLR were taken from all patients. Radiographs were digitized to calculate vertebral body morphometrics including vertebral height ratio and Cobb's kyphotic angle. The intensity of the patient's pain was assessed by the visual analogue scale (VAS) on the day before operation and 1 day, 1 month, and 4 months after operation. The patient's VAS scores and image measurement results were assessed with the paired t-test and Pearson correlation tests; Mann-Whitney U test was used for VAS subgroup comparison. Significance was defined as p < 0.05.

Results: IVCs in patients with not-severely collapsed VCFs were detected in 21 vertebrae (72.4%) by MRI, in 15 vertebrae (51.7%) by preoperative SuLR, and in 7 vertebrae (24.1%) by preoperative StLR. Using the MRI as a gold standard to detect IVCs, SuLR exhibit a sensitivity of 0.71 as compared to StLR that yield a sensitivity of 0.33. In patients with VCFs with IVCs detected on SuLR, the average of the postoperative restoration in vertebral height ratio was significantly higher than that in those without IVCs (17.1% vs. 6.4%). There was no statistical difference in the VAS score between severely collapsed VCFs with IVCs detected on SuLR and not-severely collapsed VCFs at any follow-up time point.

Conclusions: The SuLR efficiently detects an IVC in VCF, which indicates a better vertebral height correction after vertebroplasty compared to VCF without IVC. Before performing a costly MRI, SuLR can identify more IVCs than StLR in patients with severely collapsed VCFs, whom may become the candidates for vertebroplasty.

Figure 1

The measurement of vertebral height ratio. The vertebral height (VH) is the distance between the midpoints of upper and lower endplates of the index vertebra on the lateral views. The VH ratio of the index vertebra was then calculated as the VH of the index vertebra (A) divided by the average of the VHs 1 level above (B1) and below the index vertebra (B2).

Figure 2

The intravertebral cleft detected on the supine lateral radiograph. A 93-year-old male patient with T12 severely collapsed vertebral compression fracture (VCF) with preoperative VAS score of 9, vertebral height (VH) ratio of 24.5%, and a kyphotic angle of 31.9° on the preoperative standing lateral radiograph (StLR) (A). The supine lateral radiograph (SuLR) (B) revealed an intravertebral cleft (IVC) and the VH ratio and kyphotic angle were reduced to 39.9% and 14.1°, respectively. We performed T2-weighted MRI (C) to confirm the level of symptomatic VCF at 12 weeks after a fall from standing height, which showed an IVC with fluid sign. The postoperative StLR (D) showed that the VH ratio and kyphotic angle were restored to 60% and 24.3°, respectively. The VAS score of this patient decreased to 3, 1, and 0 points at day 1, 1 month, and 4 months, respectively, post operation. (* T12 vertebra)