Effects of prolonged weak anodal direct current on electrocorticogram in awake rabbit.

The effects of prolonged weak anodal direct current (DC) on the electrocorticogram (ECoG) were investigated in awake rabbits. When the current (20-40 microA) was applied to the motor region of the cerebral cortex, seizure activity in the ECoG appeared from the frontal cortex. Repeated application of the DC decreased the threshold current for producing the seizure activity. Diazepam significantly elevated the threshold of the seizure activity. In contrast to the marked changes in the ECoG, no behavioral changes were observed during or after the application of weak anodal DC. The changes in the ECoG are discussed in relation to the intensity and duration of the DC.</p

Ability of a Novel Foot and Ankle Loading Device to Reproduce Loading Conditions in the Standing Position During Computed Tomography

To describe a loading device, we created for use with current computed tomography (CT) scanners and to evaluate its ability to reproduce loading conditions. Ten feet of five healthy volunteers (three men and two women) with no history of foot or ankle disorders and no foot pain were studied. Subjects lay on the device in the supine position with the legs extended and ankles in a neutral position. An axial load equivalent to their body weight was applied to the soles. A foot scan measured plantar contact area, plantar pressure, and the center of pressure under standing and weight-bearing conditions. Differences between measurements were assessed using the paired t test with a two-sided significance of 5%. No subjects complained of pain or discomfort during loading. Weight-bearing measurements varied from standing measurements as follows: plantar contact area, À4.15 cm 2 ; contact % (forefoot/midfoot/hindfoot), À0.61%/À0.17%/0.79%; plantar pressure, À1.47 N/cm 2 /À0.49 N/cm 2 /3.7 N/cm 2 (6.40 N/cm 2 overall); and center of pressure location (anterior-posterior/ medial-lateral), 0.88%/0.36%. With the numbers available, no significant difference could be detected for any tested items. We were able to produce load distributions and intensities resembling standing conditions. Thus, the standing condition can be well produced on CT images if our device is used. Furthermore, images can be compared with those of healthy individuals to yield useful information for elucidating the pathophysiology and pathology of foot disorders

Three-Dimensional Analysis of Windlass Mechanism Using Loading Computed Tomography in Patients With Hallux Rigidus and Healthy Volunteers

Category: Midfoot/Forefoot; Basic Sciences/Biologics Introduction/Purpose: The windlass mechanism (WM) increases the height of the medial longitudinal arch (MLA) of the foot by tensing the plantar aponeurosis during dorsiflexion of the metatarsophalangeal (MTP) joint. We speculated that this mechanism may be deeply involved in the pathogenesis of forefoot diseases such as hallux rigidus (HR). These conditions are three- dimensional (3D) deformities including rotational deformity, but the role of the WM has been evaluated only two-dimensionally by measuring the height of the navicular on lateral plain radiographs. The purpose of this study was to analyze in detail the WM of normal and HR feet in 3D. Methods: Participants were 14 patients with HR (17 feet) and 13 volunteers (21 feet). The volunteers had no history of foot disease or trauma, whereas the patients with HR had Coughlin and Shurnas classification I or II. Computed tomography (CT) of the foot with a load equivalent to the participant’s body weight was performed. Imaging was performed with the 1st MTP joint in the neutral position and dorsiflexed 30 degrees. 3D models were created using the software Mimics Research 17.0. Next, we used the iterative closest point (ICP) algorithm, which allows 3D objects to be superimposed without specifying anatomical feature points. Then, we performed 3D measurements of the (1) rotation of each bone in the MLA with respect to the tibia, (2) rotation of the distal bone in each joint of the MLA, and (3) changes in the height of the geometric center of the navicular. Results: At the calcaneus, navicular and medial cuneiform, the HR group showed less inversion, adduction than healthy group. (P < 0.05) At the talonavicular joint, the navicular was 3.7° inversion, 2.9° adduction in the healthy group and 2.4°inversion, 1.3° adduction in the HR group. At the talocalcaneal joint, the calcaneus was 1.7° inversion, 1.5° adduction in the healthy group and 0.9°inversion, 0.6° adduction in the HR group. In the talonavicular and talocalcaneal joint, the HR group showed less inversion and adduction than control. (P < 0.05) With dorsiflexion of the hallux, the height of the navicular increased by 2.1 mm in the healthy group and 1.3 mm in the HR group. There was a significant difference (P < 0.05) between the two groups. Conclusion: In both groups, the calcaneus, navicular, and medial cuneiform bones moved not only in the sagittal plane but also in the frontal plane. But the movement of the talonavicular and talocalcaneal joints and the change in height of the navicular were significantly reduced compared with the healthy group. In other words, in the HR group, the motion of the midfoot and hindfoot was limited, suggesting that there may be a close relationship between WM dysfunction and midfoot and hindfoot motion. This study indicates that the dysfunction of the WM may have been a clue to the cause of HR