Importance of intravertebral fracture clefts in vertebroplasty outcome.

OBJECTIVE: The importance of filling intravertebral fracture clefts with polymethylmethacrylate during percutaneous vertebroplasty to maximize stabilization of fracture fragments has been emphasized in the literature. The purpose of this study was to determine whether patients with a single compression fracture with an intravertebral cleft have better outcome after percutaneous vertebroplasty than do patients with a compression fracture but no cleft. MATERIALS AND METHODS: A retrospective study was conducted to review 354 consecutive percutaneous vertebroplasty procedures on 694 compression fractures. Patients were excluded from consideration if they were treated for metastatic compression fracture or if they were treated at more than a single vertebral body level. Sixty-five patients met the inclusion criteria. Preprocedure radiographs and MR images were reviewed with specific attention to the presence or absence of intravertebral gas or fluid. Images obtained at the procedure also were reviewed for the presence or absence of an intravertebral cleft. Imaging findings were correlated with subjective pain scores immediately, 2 weeks, 1 month, 3 months, 6 months, 1 year, and 2 years after the procedure. RESULTS: Thirty-one (48%) of the 65 patients had evidence of a fracture cleft. Twenty-seven patients had opacification of an intravertebral fracture cleft at percutaneous vertebroplasty, and four patients had an intravertebral cleft on preprocedure imaging but did not have cleft opacification. Thirty-four (52%) of the patients had no evidence of a fracture cleft and had only a trabecular pattern of opacification. Although there was a trend toward a greater failure rate in patients with a filled cleft, there was no statistically significant difference in subjective pain scores between the groups. CONCLUSION: Pain relief with vertebroplasty is similar in patients with and those without intravertebral fracture clefts. Because of the small number of unfilled fracture clefts in our population, the true incidence of post-percutaneous vertebroplasty pain in patients with an un-filled cleft remains uncertain.

Prediction of atrial fibrillation following cardiac surgery using rough set derived rules.

Atrial fibrillation (AF) and flutter are common following cardiac surgery, increasing costs and morbidity. Cardiologists need a method to discern those patients who are at high risk for this arrhythmia in order to attempt to treat them by either pharmacologic or non-pharmacologic means. We performed a retrospective analysis of 377 CABG patients, of which 94 developed AF post-operatively. Feature selection and AF occurrence prediction was performed using a multivariate regression model, and two rough set derived rule classifiers. The rough set derived feature subset performed best with an accuracy of 87%, a sensitivity of 58.5%, and a specificity of 96.5%. This shows the importance of testing feature subsets, thereby discouraging the practice of simply combining the best individual predictors. The utility of rough set theory in prediction of cardiac arrhythmia is also validated.