Development of gait segmentation methods for wearable foot pressure sensors.

We present an automated segmentation method based on the analysis of plantar pressure signals recorded from two synchronized wireless foot insoles. Given the strict limits on computational power and power consumption typical of wearable electronic components, our aim is to investigate the capability of a Hidden Markov Model machine-learning method, to detect gait phases with different levels of complexity in the processing of the wearable pressure sensors signals. Therefore three different datasets are developed: raw voltage values, calibrated sensor signals and a calibrated estimation of total ground reaction force and position of the plantar center of pressure. The method is tested on a pool of 5 healthy subjects, through a leave-one-out cross validation. The results show high classification performances achieved using estimated biomechanical variables, being on average the 96%. Calibrated signals and raw voltage values show higher delays and dispersions in phase transition detection, suggesting a lower reliability for online applications.

Late results of modified Mitchell procedure for the treatment of hallux valgus.

From a total of 153 patients (251 feet), 64 (41.8%) patients, who had had 105 modified Mitchell procedures, were clinically and radiographically examined with follow-up periods ranging from 15 to 24 years (mean, 21 years). Mean age at operation was 41 years (range, 12-64 years). The classic double osteotomies, which diverged slightly toward the plantar surface and the distal fragment, shifted laterally, and angled plantarward, were fixed with a smooth Kirschner wire. In this way, it was possible to achieve a reduction in the first intermetatarsal angle from an average of 22.5 degrees preoperatively to 7.7 degrees postoperatively, and the hallux valgus angle changed from an average of 33 degrees to 17 degrees, with an average shortening of the first metatarsal of 5.4 mm and an average lateral displacement of the first metatarsal head of 4.5 mm. In 67 feet (64%), the results were graded good to excellent; in 23 feet (22%), satisfied; and in 15 feet (14%), poor. The results were worse than the results obtained on the same patient population with a follow-up ranging from 2 to 11 years, with 97% good-to-excellent results reported. Pain over bunion caused by recurrence of the hallux valgus deformity was the main reason for this late deterioration of the results.