Early and long-term changes in adjacent vertebral body bone mineral density determined by quantitative computed tomography after posterolateral fusion with transpedicular screw fixation.

OBJECTIVE: The aim of this study is to investigate vertebral body bone mineral density (BMD) changes following posterolateral fusion with transpedicular screw fixation using quantitative computerized tomography (QCT) in short and relatively long-term periods. PATIENTS AND METHODS: A retrospective study was performed to investigate vertebral body BMD changes in the patients who underwent posterolateral fusion with transpedicular screw fixation at thoracic and lumbar spine. A total of 160 patients were enrolled into the study. According to the follow-up period, patients were divided into two subgroups (group 1, early follow-up, mean follow-up period, 279.3±162.3 days and group 2, later follow-up, mean follow-up period, 969.1±274.2 days). The trabecular BMDs (mg/cm³) were measured from T12 to L5 as screw free levels by using QCT measurement software. Comparisons between preoperative and postoperative BMD values were assessed using paired t-test. RESULTS: The mean postoperative BMD values of both group 1 and 2 weresignificantly lower, compared with the preoperative values (79.2±31.3mg/cm³ vs. 91.5±31.4mg/cm(3), 76.1±25.5mg/cm(3) vs. 89.3±30.4mg/cm(3), p<0.001 and p<0.001, respectively). There was no significant correlation between BMD loss and number of fused segments. Vertebral BMD loss was significantly higher in the L3 vertebra when located caudally to the operation site than when located cranially (-27.7±19.8% vs. -12.8±27.1%; p<0.01). CONCLUSIONS: The vertebral body BMD values are decreased at the adjacent of the posterolateral fusion with transpedicular screw fixation levels in both cephalad and caudad sides at an average of 9-months-follow-up postoperatively. This BMD loss persisted, but not worsened at an average of 32-months-follow-up. Vertebral BMD loss was significantly higher in the L3 vertebra when located caudally versus cranially to the surgery site.

Evaluation of computed tomography findings for success prediction after extracorporeal shock wave lithotripsy for urinary tract stone disease.

PURPOSE: Currently, the most widely used method of treatment of urinary tract stones is extracorporeal shock wave lithotripsy (SWL). Patient and stone characteristics are important for SWL success. We evaluated noncontrast computed tomography (NCCT) characteristics of urinary tract stones for the prediction of SWL success. METHODS: Records of patients who underwent NCCT before SWL treatment between January 2008 and June 2012 were retrospectively evaluated. Demographic data were recruited from patient files. Hounsfield units (HU), stone size and skin-to-stone distance (SSD) were measured on NCCT. After serial measurements of the highest HU value (HUmax) and lowest HU value (HUmin), HU value was calculated as the average of these two values (HUave). These parameters were compared between successful [stone-free (SF) group] and unsuccessful [residual fragment (RF) group] cases after SWL. RESULTS: A total of 254 patients, 113 kidney stones and 141 ureteral stones, were evaluated. Mean age was 51.0±14.6 (18-87) years, and mean stone size was 10.9±3.7 mm. Stone diameter, HUmax, HUmin and HUave were significantly lower in SF group when compared with RF group for both kidney and ureteral stones (p<0.05). We also found that SSD for kidney stones was predictive for SWL success. CONCLUSIONS: We suggest that HUmax, HUmin and HUave values are significant predictors of SWL success for both kidney and ureteral stones. They might be used in daily clinical practice for patient counselling.