Percutaneous vertebroplasty is an efficient procedure to treat pain due to osteoporotic vertebral compression fractures. However, refracture of cemented vertebrae occurs occasionally after vertebroplasty. It is unclear whether such fractures are procedure-related or part of the natural course of osteoporosis. The effect of potentially important covariates on refracture risk in cemented vertebrae has not been evaluated previously. We retrospectively analyzed the incidence and possible causative mechanism of refracture in patients who had received only one vertebroplasty for a single level of vertebral compression fracture. We assessed the following covariates: age, sex, body weight, height, lumbar spine bone mineral density, treated vertebral level, pre-existing untreated vertebral compression fracture, and gas-containing vertebrae before treatment. Surgical variables, including surgical approach, cement injected, and anterior vertebral height restoration, were also analyzed. Antiosteoporotic treatment after surgery was recorded. Multiple logistic regression analysis was used to determine the relative risk of refractures of cemented vertebrae. Over all, 98 patients were evaluated with a mean follow-up of 26.9 ± 12.4 months (range, 7-55 months). We identified 62 refractures and the mean loss of anterior vertebral height was 13.3% (range 3.2-40.3%). The greater the anterior vertebral height obtained from vertebroplasty, the greater the risk of refracture occurring (P \ 0.01). Gas-containing vertebrae were also prone to refracture after the procedure (P = 0.01). Anti-osteoporotic treatment was of borderline significance between refractured and non-refractured vertebrae (P = 0.07). Only restoration of anterior vertebral height was positively associated with refracture during the follow-ups (P \ 0.01). In conclusion, refractures of cemented vertebrae after vertebroplasty occurred in 63% of osteoporotic patients. Significant anterior vertebral height restoration increases the risk of subsequent fracture in cemented vertebrae.

Complex biomolecules absorb in the mid-infrared ( ‫؍‬ 2-20 m), giving vibrational spectra associated with structure and function. We used Fourier transform infrared (FTIR) microspectroscopy to "fingerprint" locations along the length of human small and large intestinal crypts. Paraffinembedded slices of normal human gut were sectioned (10 m thick) and mounted to facilitate infrared (IR) spectral analyses. IR spectra were collected using globar (15 m ؋ 15 m aperture) FTIR microspectroscopy in reflection mode, synchrotron (<10 m ؋ 10 m aperture) FTIR microspectroscopy in transmission mode or near-field photothermal microspectroscopy. Dependent on the location of crypt interrogation, clear differences in spectral characteristics were noted. Epithelial-cell IR spectra were subjected to principal component analysis to determine whether wavenumber-absorbance relationships expressed as single points in "hyperspace" might on the basis of multivariate distance reveal biophysical differences along the length of gut crypts. Following spectroscopic analysis, plotted clusters and their loadings plots pointed toward symmetric ( s )PO 2 ؊ (1,080 cm ؊1 ) vibrations as a discriminating factor for the putative stem cell region; this proved to be a more robust marker than other phenotypic markers, such as ␤-catenin or CD133. This pattern was subsequently confirmed by image mapping and points to a novel approach of nondestructively identifying a tissue's stem cell location. s PO 2 ؊ , probably associated with DNA conformational alterations, might facilitate a means of identifying stem cells, which may have utility in other tissues where the location of stem cells is unclear.

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