This study investigated the prevalence of the intravertebral vacuum phenomenon (IVP) and osteonecroses in vertebral compression fractures (VCFs). We therefore performed an histological analysis of biopsies obtained from VCFs prior to balloon kyphoplasty. Computed tomography (CT) scans were reviewed regarding the presence of an IVP (i.e. cleft sign, Kümmell disease). We reviewed the data of 266 consecutive patients treated by balloon kyphoplasty in 501 procedures from 2002 to 2004. From 180 patients (68%) we obtained adequate bone tissue for histological evaluation. Biopsy specimens were analysed regarding the presence of osteoporosis, infection, malignancy and osteonecrosis. CT scans of all 180 patients were reviewed for presence of an IVP. Histological examination revealed 135 (75%) osteoporoses, 20 (11%) neoplasms, 12 (7%) trauma cases and 13 (7%) osteonecroses. An IVP was present in 12 (7%) patients. There was a significant association of osteonecrosis and IVP (P < 0.0001). Eleven of 12 patients with a vacuum phenomenon showed an osteonecrosis on histology, whereas 11 of 13 patients with osteonecrosis showed an IVP on CT. The IVP is a specific sign of osteonecrosis in vertebral compression fractures (sensitivity 85%, specificity 99%, positive predictive value 91%). Our findings strongly support the thesis that an IVP indicates local bone ischemia associated with a non-healing vertebral collapse and pseudarthrosis.
CaP cement, e.g., Calcibon, is as effective and safe as conventional PMMA-cement with regard to immediate and sustained pain reduction and improvement of mobility after kyphoplasty of patients with painful osteoporotic vertebral fractures. CaP cement has the potential of being resorbed and replaced by newly formed bone tissue; thus, it seems to be a promising alternative for PMMA also in younger patients with painful vertebral fractures.
BackgroundCalcium phosphate cements are used frequently in orthopedic and dental surgeries. Strontium-containing drugs serve as systemic osteoblast-activating medication in various clinical settings promoting mechanical stability of the osteoporotic bone.MethodsStrontium-containing calcium phosphate cement (SPC) and calcium phosphate cement (CPC) were compared regarding their local and systemic effects on bone tissue in a standard animal model for osteoporotic bone. A bone defect was created in the distal femoral metaphysis of 60 ovariectomized Sprague-Dawley rats. CPC and SPC were used to fill the defects in 30 rats in each group. Local effects were assessed by histomorphometry at the implant site. Systemic effects were assessed by bone mineral density (BMD) measurements at the contralateral femur and the spine.ResultsFaster osseointegration and more new bone formation were found for SPC as compared to CPC implant sites. SPC implants exhibited more cracks than CPC implants, allowing more bone formation within the implant. Contralateral femur BMD and spine BMD did not differ significantly between the groups.ConclusionsThe addition of strontium to calcium phosphate stimulates bone formation in and around the implant. Systemic release of strontium from the SPC implants did not lead to sufficiently high serum strontium levels to induce significant systemic effects on bone mass in this rat model.
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