Modeling and Simulation of an Assistive Exoskeleton Leg System with Knee Osteoarthritis and Quadriceps Weakness

The most common human locomotion problems such as quadriceps weakness, knee osteoarthritis can be healed up by using exoskeleton mechanisms with proper control systems. However, these kinds of abnormalities cannot be easily modeled in terms of engineering perspectives due to a lack of adequate data or unknown dynamics. Also, nature always seeks minimum energy as well as biology which means that the unknown dynamics can be built by using this phenomenon. In this study, a new system dynamic model had been involved in designing a simple single-legged exoskeleton robot mechanism and its control system to assist partially disabled individuals to improve their quality of locomotion. To determine the specific features of the human gait disorders to interpret their nature in the computer-aided simulation environment, knee osteoarthritis and quadriceps weakness, which are the common types of such problems, have been chosen as the main interests for this study. By using the lower limb model with anthropometric data, the simulations of disorders have been realized on MATLAB Simscape environment which enables us to model the entire exoskeleton system with the 3D parts of the human body. A model of a leg with the disorder was able to be obtained with the utilization of feedback linearization which is one of the examples of minimum principles in the control theory. A proper gait cycle is achieved with the exoskeleton application and separately for the leg, with approximately 10 deg deviation from the natural property in knee flexion. Finally, it can be seen that the system conversion into such problematic cases with or without an exoskeleton system is accomplished.

Tourniquets and Adductor Canal Blocks in Total Knee Arthroplasty: Is There a Synergistic Effect on Postoperative Pain and Quadriceps Weakness?

Background and Hypothesis: Adequate pain control and avoidance of falls are crucial for successful early recovery following total knee arthroplasty (TKA). Studies have shown an increase in postoperative quadriceps weakness (QW) and pain associated with tourniquet use during TKA. Additionally, increasing doses of adductor canal block (ACB) anesthetic per unit of BMI are associated with QW after TKA. This retrospective cohort study examined whether tourniquets and ACBs have a synergistic effect on postoperative QW and pain. Experimental Design or Project Methods: 348 TKAs in 319 patients performed by a single surgeon between October 2015 and May 2018 were retrospectively reviewed. Outcomes included QW as documented in the physical therapy evaluation, average pain score during the first 24 hours after PACU discharge, average pain score during the remainder of the hospital stay, and final pain score prior to discharge. Results: Sex, age, and BMI did not differ in patients with ACBs with (n=177) and without (n=168) tourniquet use (p≥0.330). The overall prevalence of QW in the sample was 8.7%. Proportionally more patients with ACBs and tourniquets (11.6%) had QW compared to patients with ACBs without tourniquets (6.1%), but the difference was not statistically significant with the numbers available. Patient-reported pain scores at the three time points did not differ significantly between patients who received ACBs with or without tourniquets. Conclusion and Potential Impact: There appears to be no synergistic effect of ACBs and tourniquet use on postoperative pain. However, due to the effect size and number of cases in each group, the synergistic effect of ACBs and tourniquet use on QW deserves additional study with a larger sample size as these results may impact functional recovery and postoperative complications among patients undergoing primary TKA.

Quadratus lumborum block type 3 versus lumbar plexus block in hip replacement surgery: a randomized, prospective, non-inferiority study

IntroductionThe posterior lumbar plexus block (LPB) has been used for decades to provide acute pain management after hip surgery. Unfamiliarity with the technique and its perceived difficulty, potential risks, and possible adverse effects such as quadriceps weakness have limited broader use. The quadratus lumborum block (QLB) has been reported to be effective for postoperative pain control following hip surgery and may thus offer another regional alternative for practitioners. This study hypothesized that the QLB type 3 (QLB3) can produce a non-inferior analgesic effect compared with LPB for primary hip replacement.MethodsThis double-blinded, non-inferiority trial randomized 46 patients undergoing primary hip replacement to receive either QLB3 or LPB. Outcomes were assessed on postanesthesia care unit arrival and at postoperative hours 6, 12, and 24. The primary outcome measured was numeric rating scale (NRS) pain score 24 hours after surgery. Secondary outcomes included opioid consumption, presence of quadriceps weakness at first postoperative physical therapy (PT) session, and time to achieve 100 feet of walking.ResultsThe QLB3 did not cross the non-inferiority delta of 2 points on the NRS pain score (mean difference −0.43 (95% CI −1.74 to 0.87)). There were no significant differences between groups in total opioid consumption at 24 hours or in time to achieve 100 feet of walking. Quadriceps weakness at first PT session was less common with QLB3 (26% vs 65%) and time to perform the block was significantly less with QLB3 (10 min vs 5 min).ConclusionThis trial supported the hypothesis that the QLB3 yields non-inferior analgesia compared with LPB for hip replacement surgery.Trial registration numberNCT03801265.