A Marching Cubes Algorithm: Application for Three-dimensional Surface Reconstruction Based on Endoscope and Optical Fiber

International audienceIn this paper, a marching cubes (MC) algorithm is presented for the three-dimensional (3-D) surface reconstruction based on endoscope images. In general, the classical MC algorithm processes the 3-D medical images obtained from computed tomography (CT) or magnetic resonance (MR), while the volumetric data described in this work are not. Therefore, the purpose of this study mainly focuses on: (1) An active endoscope scanning system that equips an endoscope and optical fiber using for profile measurement of the object, is described in detail; (2) A novel method is also presented to create the regular 3-D grid, which is suitable specifically for the data type of endoscope images. The average errors of the endoscope system on depth detection and surface recover were about 0.50 mm (standard deviation, 0.991) and 2.39 mm (standard deviation, 0.759), respectively. Experimental results on several realistic reconstruction demonstrate the feasibility and good performance of the proposed approach

Migration Measurement of Pins in Postoperative Recovery of the Proximal Femur Fractures Based on 3D Point Cloud Matching

Background and objectives: Internal fixation is one of the most effective methods for the treatment of proximal femur fractures. The migration of implants after the operation can seriously affect the reduction of treatment and even cause complications. Traditional diagnosis methods can not directly measure the extent of displacement. Methods: Based on the analysis of Hansson pins, this paper proposes a measurement method based on three-dimensional matching, which uses computerized tomography (CT) images of different periods of patients after the operation to analyze the implants’ migration in three-dimensional space with the characteristics of fast speed and intuitive results. Results and conclusions: The measurement results show that the method proposed in this paper has more minor errors, more flexible coordinate system conversion, and more explicit displacement analysis than the traditional method of manually finding references in CT images and measuring displacement

Plantar pressure sensors indicate women to have a significantly higher peak pressure on the hallux, toes, forefoot, and medial of the foot compared to men

Background Sex-related differences of plantar pressure distribution during activities should be thoroughly inspected as it can help establish treatment and prevention strategies for foot and ankle problems. In-shoe measurement systems are preferable without space and activity restrictions; however, previously reported systems are still heavy and bulky and induce unnatural movement. Therefore, a slim and light plantar pressure sensor was newly developed to detect the effect of sex difference on plantar pressure during standing and walking. Methods One-hundred healthy adult volunteers (50 women and 50 men) were recruited. Ten plantar pressure sensors were implanted in a 1-mm thick insole, with a total weight of 29 g. Plantar pressure was recorded with 200 Hz during 3 s of standing and while walking 10 steps. The maximum loads during standing and walking were analyzed in each sensor, and the results were compared between different areas of the foot in the antero-posterior direction and the medio-lateral direction and between different time points. The movement of the center of pressure (COP) during walking was also evaluated. Analyses were adjusted for body mass index and gait speed. Results The movement of COP was constant for both sexes. In all cases, the maximum load was observed on the medial of the foot. Women had a significantly higher peak pressure on the hallux, toes, forefoot, and medial aspect of the foot compared to men while standing and walking (p < .05). Conclusions A newly introduced in-shoe plantar pressure sensor demonstrated a typical loading transition pattern of the foot. Furthermore, higher plantar pressure in the forefoot was detected in healthy women as compared to men during standing and walking activities