The study aims were to estimate the radiation dose in patients examined with low dose spine CT and to compare it with that received by patients undergoing standard CT for trauma of the same region, as well as to evaluate the impact of dose reduction on image quality. Radiation doses in 113 consecutive low dose spine CTs were compared with those in 127 CTs for trauma. The inter- and intraobserver agreement in measurements of pedicular width, and vertebral rotation, measurements of signal-to-noise ratio and assessment of hardware status were the indicators in the evaluation of image quality. The effective dose of the low dose spine CT (0.37 mSv) was 20 times lower than that of a standard CT for trauma (13.09 mSv). This dose reduction conveyed no impact on image quality. This low dose spine CT protocol allows detailed evaluation that is necessary for preoperative planning and postoperative evaluation.

In electromyographic (EMG) and functional magnetic resonance imaging (fMRI) studies, muscle and brain activity was compared during low levels of tooth clenching using a novel biting device to control bite force. A total of 21 healthy subjects performed motor tasks, comprising tooth clenching at 5, 10 and 20 N. During all measurements, subjects kept the novel bite device between the anterior teeth during tooth clenching. The EMG study (n = 15) characterised jaw muscle activity for the three motor tasks and demonstrated significant differences in root mean square (RMS) EMG amplitude between 5-, 10- and 20-N tooth clenching (F = 46.21, P < 0.001). There were no differences in variability of muscle activity between the three tooth-clenching levels. In an fMRI pilot study (n = 6), statistical comparisons were used to identify brain regions with significant activation in the subtraction of baseline from 5- or 20-N tooth-clenching activity. 5- and 20-N tooth clenching significantly and bilaterally activated the sensorimotor cortex, supplementary motor area, cerebellum and basal ganglia (P < 0.05, corrected for multiple comparisons). However, activation of each brain region did not differ significantly between two tooth-clenching tasks. Based on these preliminary findings, we propose that the novel biting device may be useful in further fMRI studies on controlled jaw muscle activation patterns in different craniofacial pain conditions. In addition, our fMRI result suggests that there are no significant differences in brain activity within low levels of tooth clenching with controlled force.

Osteonecrosis of the femoral head following femoral neck fractures is a common condition. Spontaneous osteonecrosis, is, however, a rare disorder, which is observed with increased frequency in alcohol abusers. In this retrospective study, we followed 512 consecutive male patients who had sustained femoral neck fractures between 1984 and 1992; 82 of these 512 patients (16%) had earlier been registered at the Department of Alcohol Diseases as high consumers of alcohol. The aim of the study was to determine the relationship between the rate of healing complications and alcohol consumption. No differences were observed in the degree of fracture dislocation, frequency of femoral head necrosis, and pseudoarthrosis among the abusers. Furthermore, no differences were found in causative events, primary operative treatment, post-operative complications, and the number of secondary operations. The abusers were significantly younger, had a higher rate of early retirement, and had an increased death rate. Our study suggests that alcohol complicates the healing process to a lesser extent than earlier thought, and that osteonecrosis of the femoral head after femoral neck fractures is equally common in non-abusers as in abusers.