Cornejo, Jorge

Stroke is the second leading cause of death globally and a major contributor to lower-limb disability, affecting gait, balance, and functional independence in elderly populations. While robot-assisted rehabilitation has demonstrated effectiveness in motor recovery, access remains limited due to high costs and geographic barriers, particularly in Latin America. This study presents ExoKnee, a low-cost knee exoskeleton designed through biomimetic principles and 3D-printed fabrication as a proof-of-concept device targeting gait rehabilitation in elderly adults. The system integrates a single-degree-of-freedom pneumatic actuator controlled by electromyography (EMG) signals from the quadriceps muscle, enabling knee flexion and extension (90° to 180°). The design was evaluated through finite element analysis and dynamic simulations in MATLAB/Simulink R2024a under constant, stepwise, and sinusoidal reference inputs in a digital-twin environment. Expert validation using the Content Validity Coefficient yielded a mean score of 0.8747, reflecting preliminary expert agreement on the conceptual design’s coherence and relevance. The prototype demonstrated controlled movements through a 6-bar pneumatic system with EMG-triggered relay activation, validated at the proof-of-concept level through simulation and single-subject threshold calibration. ExoKnee addresses critical gaps by offering an anthropometrically informed, biosignal-driven, and locally manufacturable rehabilitation platform for low- and middle-income countries, pending clinical validation. Future work will focus on clinical trials and adaptive EMG control strategies.

Background: Revisional bariatric surgery for recurrent weight gain is becoming more common, though it carries higher risks and may be less effective than primary bariatric surgery. This study compares clinical outcomes between primary and revisional duodenal switch (DS) in patients with a body mass index (BMI) > 55 kg/m2. Methods: A retrospective cohort study was conducted on 20 patients who underwent either primary or revisional duodenal switch (DS) surgeries, including biliopancreatic diversion with duodenal switch (BPDDS) and Single-Anastomosis Duodeno-Ileal Bypass with Sleeve Gastrectomy (SADI-s), between January 2015 and December 2023. Revisional DS was defined as the conversion from Sleeve Gastrectomy (SG) to either BPDDS (C-BPDDS) or SADI-S (C-SADI-S). Perioperative and postoperative variables were analyzed. A statistical analysis was performed using chi-square and McNemar tests for categorical variables and Student’s t-test for continuous variables. A p-value of <0.05 was considered significant. Results: Eleven primary DS patients (six BPDDS, five SADI-s) and nine revisional DS patients (five C-BPDDS, four C-SADI-s) were included. The revisional group had a slightly higher preoperative BMI (57.56 ± 5.92 kg/m2 vs. 55.93 kg/m2 ± 6.91 kg/m2). Although operative times were shorter in the revisional group (153.20 ± 53.26 vs. 193.27 ± 46.79 min), the length of stay was longer (2.70 ± 1.25 vs. 2.18 ± 1.16 days). Primary DS patients experienced three minor late complications (dehydration, nephrolithiasis), whereas the revisional group had one major complication (internal hernia requiring reoperation). At the 12-month follow-up, both groups demonstrated similar outcomes in terms of percentage of total weight loss (%TWL) (primary DS: 25.25% ± 12.38 vs. revisional DS: 30.31% ± 10.79) and percentage of excess weight loss (%EWL) (primary DS: 48.41% ± 22.93 vs. revisional DS: 53.24% ± 14.48). Conclusions: Revisional DS was associated with shorter operation times and similar weight loss to primary DS. Additionally, it was accomplished safely and led to adequate and sustained weight loss in patients with a BMI greater than 55 kg/m2.

Revisional metabolic and bariatric surgery (RMBS) presents unique challenges in addressing weight loss failure or complications arising from initial bariatric procedures. This review aims to explore the complexities and solutions associated with revisional bariatric procedures comprehensively, offering insights into the evolving terrain of metabolic and bariatric surgery. A literature review is conducted to identify pertinent studies and expert opinions regarding RMBS. Methodological approaches, patient selection criteria, surgical techniques, preoperative assessments, and postoperative management strategies are synthesized to provide a comprehensive overview of current practices and advancements in the field, including institutional protocols. This review synthesizes key findings regarding the challenges encountered in RMBS, including the underlying causes of primary procedure failure, anatomical complexities, technical considerations, and assessments of surgical outcomes. Additionally, patient outcomes, complication rates, and long-term success are presented, along with institutional approaches to patient assessment and procedure selection. This review provides valuable insights for clinicians grappling with the complexities of RMBS. A comprehensive understanding of patient selection, surgical techniques, preoperative management, and postoperative care is crucial for enhancing outcomes and ensuring patient satisfaction in the field of metabolic bariatric surgery.