Heat Generation During Bony Decompression of Lumbar Spinal Stenosis Using a High-Speed Diamond Drill with or without Automated Irrigation and an Ultrasonic Bone-Cutting Knife: A Single-Blinded Prospective Randomized Controlled Study.

OBJECTIVE: The main objective of the present prospective, randomized, single-blinded controlled study was to measure heat during bony decompression of lumbar spinal stenosis with high-speed drills and an ultrasonic bone-cutting knife. METHODS: Ninety patients diagnosed with lumbar spinal stenosis were included in this study and randomized for lumbar spinal canal decompression using either a high-speed drill with automatic irrigation, high-speed drill with manual irrigation, or an ultrasonic bone-cutting knife with automatic irrigation (USBCD). For evaluation of group homogeneity, a visual analog scale pain score and neurologic findings were measured preoperatively and postoperatively. Temperatures during bony decompression were measured using a forward-looking infrared camera system. RESULTS: Clinical results among the 3 groups did not differ in pain reduction, improvement of neurologic findings, or the rate of complications. However, significantly lower values were found for absolute and mean maximal temperatures during bony decompression in the USBCD group compared with the groups of patients who received the high-speed drill with automatic irrigation and the high-speed drill with manual irrigation, indicating this technique to be less aggressive in terms of thermal induction of bone necrosis. USBCD allows more precise bone removal compared with high-speed drills, and despite increased device time, no significant difference in the overall decompression time was observed. CONCLUSIONS: All methods examined produced short temperature peaks with possible, at least temporary, damage to bone and neural tissue. Automatic irrigation was associated with lower heat development compared with manual irrigation. Despite evidence of critical temperatures, no clinical correlation (e.g., neurologic deficits) was encountered in this study. Clinically, all 3 methods presented equally good results.

Proton-density fat fraction and simultaneous R2* estimation as an MRI tool for assessment of osteoporosis.

OBJECTIVE: To investigate multi-echo chemical shift-encoded MRI-based mapping of proton density fat fraction (PDFF) and fat-corrected R2* in bone marrow as biomarkers for osteoporosis assessment. METHODS: Fifty-one patients (28 female; mean age 69.7 ± 9.0 years) underwent dual energy X-ray absorptiometry (DXA). On the basis of the t score, 173 valid vertebrae bodies were divided into three groups (healthy, osteopenic and osteoporotic). Three echo chemical shift-encoded MRI sequences were acquired at 3 T. PDFF and R2* with correction for multiple-peak fat (R2*MP) were measured for each vertebral body. Kruskal-Wallis test and post hoc analysis were performed to evaluate differences between groups. Further, the area under the curve (AUC) for each technique was calculated using logistic regression analysis. RESULTS: On the basis of DXA, 92 samples were normal (53 %), 47 osteopenic (27 %) and 34 osteoporotic (20 %). PDFF was increased in osteoporosis compared with healthy (P = 0.007). R2*MP showed significant differences between normal and osteopenia (P = 0.004), and between normal and osteoporosis (P < 0.001). AUC to differentiate between normal and osteoporosis was 0.698 for R2*MP, 0.656 for PDFF and 0.74 for both combined. CONCLUSION: PDFF and R2*MP are moderate biomarkers for osteoporosis. PDFF and R2*MP combination might improve the prediction in differentiating healthy subjects from those with osteoporosis.

Comparison of waterjet dissection and ultrasonic aspiration: an in vivo study in the rabbit brain.

OBJECT: The waterjet method of dissection has been shown to enable the precise dissection of the parenchyma vessels while preserving blood in cadaveric pig brains. The waterjet device has also been applied clinically to treat various diseases and disorders without complications. Evidence still remains to be gathered as to how the instrument performs in reducing surgical trauma, intraoperative blood loss, and postsurgical brain edema. In the present study the authors investigate these parameters in a comparison between waterjet dissection and ultrasonic aspiration in the rabbit brain in vivo. METHODS: Thirty-one rabbits received identical bilateral frontal corticotomies, which were created using the waterjet device or an ultrasonic aspirator. The animals were killed 1, 3, or 7 days, or 6 weeks after surgery and their brains were processed for immunohistological analysis. Blood vessel preservation, intraoperative hemorrhage, postsurgical brain edema, and posttraumatic microglial and astoglial reactions were evaluated. Only in animals subjected to waterjet dissection were preserved vessels observed within the corticotomies. In addition, less intraoperative bleeding occurred in animals in which the waterjet was used. The microglial reaction was significantly reduced by waterjet dissection compared with ultrasonic aspiration; however, no difference in edema formation or astrocytic reactivity was observed. CONCLUSIONS: These results demonstrate that waterjet dissection appears to be less traumatic than ultrasonic aspiration with respect to intraoperative hemorrhage and postoperative microglial reactivity in the rabbit model. Nevertheless, no difference in edema formation could be demonstrated. It remains to be proven that the observed differences are of clinical relevance.