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

Wu et al. BMC Musculoskeletal Disorders 2010, 11:164 http://www.biomedcentral.com/1471-2474/11/164 RESEARCH ARTICLE Open Access Role of the supine lateral radiograph of the spine in vertebroplasty for osteoporotic vertebral compression fracture: a prospective study Meng-Huang Wu1, Tsung-Jen Huang1,2,3, Chin-Chang Cheng1,2, Yen-Yao Li1,2*, Robert Wen-Wei Hsu1,2 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. Background Vertebroplasty is a minimally invasive surgical procedure that can relieve pain caused by an osteoporotic vertebral compression fracture (VCF) [1-4]. However, VCFs that show severe vertebral body collapse to less than one-third of its original height were considered as a contraindication * Correspondence: 1 Department of Orthopedic Surgery, Chang Gung Memorial Hospital at Chiayi, Chiayi, Taiwan for vertebroplasty, because the vertebral height (VH) was too low which might hinder needle placement within the vertebral body [5,6]. Furthermore, severely collapsed VCFs are often accompanied by significant kyphosis associated with an inferior outcome after vertebroplasty [2]. However, we had observed that the VH of severely collapsed VCFs increased on supine lateral radiographs (SuLR) compared with standing lateral radiographs (StLR). McKiernan et al. [7] had reported that SuLR could demonstrate the dynamic mobility of the vertebral body and formation of © 2010 Wu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Wu et al. BMC Musculoskeletal Disorders 2010, 11:164 http://www.biomedcentral.com/1471-2474/11/164 Page 2 of 6 intravertebral clefts (IVCs) in nonunion of VCFs. These mobile VCFs are mechanically unstable and can be managed by vertebroplasty or kyphoplasty [8]. Significant height recovery and improved sagittal alignment after postural reduction could be demonstrated for these mobile, severely collapsed VCFs resulting in pain relief after vertebroplasty or kyphoplasty [8,9]. The purposes of this study were to: (1) evaluate the efficacy of SuLR to detect IVCs and assess the intravertebral mobility in osteoporotic VCFs in comparison with StLR or magnetic resonance imaging (MRI) and (2) evaluate the short-term results of vertebroplasty in severely collapsed VCFs with IVCs detected on SuLR. Methods Subjects This prospective study was approved by the institutional review board of our hospital (No 99-0445B). Thirtyseven patients (29 females and 8 males; mean age, 75 years; age, 50-93 years; 40 vertebrae) with symptomatic osteoporotic VCFs were enrolled from July 2008 to April 2009 according to the CONSORT statement [10]. All of them had given informed consent to participate the study and underwent percutaneous vertebroplasty with cement augmentation and were followed up for at least 6 months. The indication for percutaneous vertebroplasty was painful osteoporotic VCF refractory to conservative treatment with severe local tenderness over the spinal process of the fractured vertebra and without focal radicular pain. Besides, in patients with severely collapsed VCFs with residual VH less than 33% of the original height, IVCs should be noted on SuLR before considering the patient for percutaneous vertebroplasty. Radiographic outcome measures Within 1 week before operation, standing anteroposterior (AP) radiograph, StLR, and SuLR of the thoraciclumbar spine were taken from all patients to identify the fractured vertebra and determine the mobile vertebra with or without IVC. MRIs were also obtained from all patients on the day of or 1 day before operation to exclude infection or pathologic fracture and to identify IVC [11]. On the day after operation, postoperative StLR was taken to evaluate the restoration of the VH and regional kyphosis, compared with preoperative StLR. The 3 radiographs (preoperative StLR, SuLR, and postoperative StLR) were digitized to measure the VH of the index vertebra, which was the distance between the midpoints of upper and lower endplates on the lateral views described by McKiernan et al. [7] (Figure 1). The VH ratio of the index vertebra was then calculated as the VH of the index vertebra divided by the average of the VH 1 level above and below the index vertebra. Figure 1 The measurement of vertebral height ratio. The vertebral height (VH) is the (...truncated)