Knee Brace Research Articles

Design and Performance Evaluation of a Fully Integrated Knitted Knee Brace for Knee Motion Sensing.

The use of e-textiles in wearable sensor design has recently received much interest in many applications, such as robotics, rehabilitation, personal wellness, and sports. Particularly in the rehabilitation domain, it has provided a potential alternative tool for telerehabilitation. In this paper, we designed and evaluated a knitted knee brace with interconnects, resistors, and sensors for real-time kinematic data acquisition. The real-time data acquisition is transmitted using a printed circuit board (PCB) connected to the knee brace through snap pins. The knitted knee brace was tested on three male and one female participant , aged between 30 and 50 years old. All participants were instructed to perform a walking activity at 1.5 km/h for a duration of 10 seconds on the Advanced Mechanical Technology, Inc (AMTI) treadmill over two sessions. The results demonstrated that the fully integrated knitted wearable knee brace could monitor and track human joint locomotion in real time with a standard deviation of 0.39V and 0.41V , respectively, for these two sessions. However, double peak signals were noticeable from the knitted knee brace at a mean of 80.54% during the gait cycles across the four subjects; this observation could be due to the coupled motion along the transverse and coronal planes during the activity.

A comparison of stiffness of six knee braces with application for posterolateral corner reconstructions.

Posterolateral corner knee injuries are clinically significant, and often require surgical reconstruction. The optimal knee brace following posterolateral corner reconstructions has not yet been determined via clinical nor biomechanical study. We sought to evaluate the stiffness of six types of knee braces to determine the ideal brace type for reducing varus forces, which may have clinical utility for posterolateral corner knee reconstruction rehabilitation. Six different groups of knee braces underwent mechanical testing: cruciate braces, cruciate braces with a valgus bend, medial unloaders, articulating sleeves, hinged braces, and tri-panel immobilizers. Each brace was fitted to the same fiberglass leg model and was secured to the testing apparatus. Force was applied under four-point bending to generate a varus moment about the artificial knee. The stiffness in Newtons per millimeter (N/mm) of each brace was calculated from the slope of the force-displacement curve. The cruciate brace with a valgus bend had the highest average stiffness at 192.61 N/mm (SD 28.53). The articulating sleeve was the least stiff with an average stiffness of 49.86 N/mm (SD 8.99). Stiffness of the cruciate brace was not statistically different compared to cruciate valgus (p = 0.083) or medial unloader (p = 0.098). In this experimental design, a cruciate brace with a valgus bend was shown to have the highest overall stiffness, while an articulating sleeve had the lowest stiffness. Future work will investigate whether this translates into clinical performance.

PATELLAR DISLOCATION AND PATELLAR INSTABILITY PANORAMIC REVIEW

Introduction: Primary patellar dislocation is usually the initial manifestation of patellofemoral instability. Among the long-term repercussions of this disorder are recurrent dislocation and indefinable knee dysfunction. At present, there is no agreement on the optimal treatment of patellar dislocation. Objective: to detail the current information related to patellar dislocation, epidemiology, mechanism of action, clinical evaluation, imaging evaluation, classification, differential diagnosis, treatment and complications of the disease. Methodology: a total of 30 articles were analyzed in this review, including review and original articles, as well as clinical cases, of which 22 bibliographies were used because the other articles were not relevant to this study. The sources of information were PubMed, Google Scholar and Cochrane; the terms used to search for information in Spanish, Portuguese and English were: patella, knee anatomy, patellar dislocation, knee instability. Results: Approximately 5% of the time it is related to osteochondral fractures. To define whether a patella is high or low, a lateral radiograph should be taken with the knee in 30° of flexion to determine Blumensaats line. The increase in the Q angle facilitates patellar dislocation. Most patellar dislocations are related to congenital anomalies of the patella or trochlea, high patella, hypoplasia of the vastus medialis and hypertrophy of the lateral retinaculum. Conclusions: Patellar dislocation is usual in individuals with connective tissue disorders and hypermobility, the patella can be dislocated laterally, superiorly or intra-articularly, presenting different mechanisms of action for each case. It is important to have a good knowledge of the anatomy and to measure the Q angle because the increase of this angle facilitates patellar dislocation. It is essential to establish the etiology of the dislocation, especially in those with recurrent dislocations as this may alter the management plan. In addition to the clinical evaluation it is important to request anteroposterior, lateral knee and axial projections. When conservative treatment is chosen, reduction and immobilization with a cast or orthosis should be performed with the knee in extension, the long knee brace can be used, with or without arthrocentesis to relieve the symptomatology; surgical treatment is mostly used in recurrent dislocations. At the moment, no surgical technique is able to correct all the problems of patellar alignment. It should be kept in mind that the surgical procedure should take into account the individuals age, diagnosis, activity level and the situation of the patellofemoral joint. Patellofemoral instability should be treated with the goal of correcting all of the alignment issues. The usual complications are loss of knee mobility, recurrent dislocation and patellofemoral pain. KEY WORDS: dislocation, patella, knee, instability.

Outcomes and Complications Following Chronic Patellar Tendon Repair: A Systematic Review.

The purpose of this systematic review is to report outcomes and complications following the reconstruction of chronic patellar tendon ruptures. Four databases (Cochrane Database of Systematic Reviews, PubMed, Embase, MEDLINE) were searched from inception to July 2021. Inclusion criteria included articles that (1) analyzed outcomes and complications following chronic patellar tendon reconstruction (>4 weeks from injury to repair), (2) were written in English, (3) greater than five patients, and (4) a minimum 2-year follow-up. Exclusion criteria included (1) non-original research and (2) patellar tendon repair/reconstruction with prior total knee arthroplasty. Data on outcome metrics and complications were extracted from the included studies and reported in a qualitative manner. Nine studies (number of patients = 96) were included after screening. Seven studies analyzed autograft reconstruction, and three of those seven studies analyzed reconstructions with additional augmentation. The remaining two studies evaluated reconstruction utilizing a bone-tendon-bone (BTB) allograft. Four of the autograft studies (n=40 patients) showed a range of post-operative mean Lysholm scores of 74-94. Additionally, four studies reported a post-operative extensor lag of 0-3°. Post-operative protocol for autograft studies included delayed motion and was either contained to a bivalved cast or a hinged knee brace for six weeks. The two allograft studies reported a range of mean Lysholm scores from 62 to 67, and each immobilized the leg in full extension until six weeks. While chronic patellar tendon ruptures are a rare injury of the extensor mechanism, there are viable options for reconstruction. Overall, chronic patellar tendon ruptures reconstructed with both autograft and allograft will provide fair to good outcomes with low complication rates. Following surgery, immobilization for at least six weeks should be emphasized to protect the graft and optimize patient outcomes.

Rotational behavior of bolted post-to-beam glulam connections with friction damped knee brace

Alternative bracing systems have been widely applied in heavy timber structures due to its contribution to lateral stiffness and strength, while the improvement in the ductility and energy dissipation capability is limited. Friction damped knee brace is applied in this paper to reinforce rotational behavior of the bolted post-to-beam glulam connections. Monotonic and cyclic loading experiments were conducted on fifteen full-scale specimens. The failure modes, elastic stiffness, moment capacity, hysteresis response and energy dissipation were evaluated and analyzed. The experimental results indicated that with the installation of friction damped knee brace, extremely large initial stiffness was achieved and the moment capacity and accumulated energy dissipation of the post-to-beam connections were increased by 207% and 950%, respectively. Moreover, a multi-segment theoretical model was proposed to predict the rotational behavior of the reinforced bolted glulam connections. The theoretically predicted moment-rotation curves showed good agreement with the experimental results.

Seismic design of buckling-restrained knee-braced frames considering cumulative damage

A buckling-restrained knee-braced frame (BRKBF) is an efficient structural system utilizing short buckling-restrained braces (BRBs) as knee bracing elements. Because of the shorter yielding core length compared to those of conventional BRBs, one of the key parameters concerning the performance of this system is the low cycle fatigue cumulative damage of the BRBs. This paper presents a seismic design method considering the cumulative damage, performance evaluation, and collapse assessment of 3-story, 6-story, and 9-story archetype BRKBFs. An energy-based plastic design method was utilized to design the example frames. The frames were then evaluated by nonlinear static analysis and multiple-stripe analysis (MSA). The results indicated that BRKBs were able to accommodate seismic motions with limited damage. The validity of the design methodology considering cumulative damage was also confirmed.

Computational Control Strategy for Reducing Medial Compartment Load in Knee Bracing with Embedded Actuator

Medial unloader braces represent a primary noninvasive approach for alleviating knee pain. However, conventional valgus unloader braces, while reducing load on the medial compartment, inadvertently increase load on the lateral compartment through rotation from adduction to abduction. This phenomenon significantly elevates the risk of damage to the lateral compartment. To address this issue, we introduce a novel embedded actuation mechanism that unloads the knee using a pioneering computational procedure. By considering the knee osteoarthritis condition, we propose the calculation of the adduction knee angle and cartilage penetration depth as surrogate parameters for assessing knee pain. Accordingly, the newly developed unloader brace redistributes the load by precisely correcting the abduction angle. Additionally, we determine the maximum required torque for effectively tracking the desired abduction angle. Then, the saturated torque through the robust control method is applied in the presence of interaction force uncertainty between the orthosis and the user. A very small femur rotation change (1.7°) from adduction to abduction in the frontal plane is adequate to significantly reduce the medial contact force (around 886 N). The required robust external abduction torque is determined to be 27.6 Nm. The result shows that the novel procedure and brace prevent excessive overloading of the lateral compartment while it unloads the medial compartment sufficiently. This innovative approach offers significant potential for optimizing unloader brace design and enhancing the management of knee osteoarthritis.

Immediate Effects of Walking With a Knee Brace After Anterior Cruciate Ligament Reconstruction: A Biomechanical, Biochemical, and Structural Approach.

Individuals who undergo anterior cruciate ligament reconstruction (ACLR) are at higher risk of posttraumatic osteoarthritis. Altered joint tissue loading caused by aberrant gait biomechanics leads to deleterious changes in joint health linked to the onset of posttraumatic osteoarthritis. Knee braces have been used to modify joint tissue loading in individuals with joint injury, yet the effects of walking with a brace after ACLR on biomechanical, biochemical, and structural cartilage outcomes are unknown. To compare biomechanical, biochemical, and structural outcomes between braced and nonbraced walking in individuals with ACLR. Crossover study. Research laboratory. A total of 34 individuals with unilateral ACLR (18 females, 16 males; time since ACLR = 50.1 ± 36.8 months). Gait biomechanics were assessed during braced and unbraced conditions on separate days. Vertical ground reaction force, knee-flexion angle, and internal knee-extension moment waveforms were evaluated throughout the stance phase and compared between conditions. Percentage changes in serum cartilage oligomeric matrix protein (%ΔCOMP) and femoral cartilage cross-sectional area (%ΔCSA) measured via ultrasound were calculated after a 3000-step walking protocol. Braced walking increased the knee-flexion angle (largest difference = 3.56°; Cohen d effect size = 1.72) and knee-extension moment (largest difference = -0.48% body weight × height; Cohen d effect size = -1.14) compared with nonbraced walking but did not influence vertical ground reaction force. Whereas no difference (P = .20) in %ΔCOMP existed between the braced and nonbraced conditions in the entire cohort (n = 30 with complete blood data), a larger increase (P = .04) in %ΔCOMP was seen during nonbraced than braced walking in individuals who demonstrated increased COMP during nonbraced walking. No difference (P = .86) in %ΔCSA was present between the braced and nonbraced conditions. Braced walking may improve sagittal-plane gait biomechanics and %ΔCOMP in a subset of individuals who demonstrate a typical increased COMP response to load (ie, increase in COMP) after nonbraced walking.

A RETROSPECTIVE REVIEW OF THE THERAPEUTIC CHALLENGES OF 16 FITBONE INTRAMEDULLARY FEMORAL LENGTHENINGS COMPLETED AT SHEFFIELD CHILDREN'S HOSPITAL BETWEEN 2021 AND 2022

IntroductionAt Sheffield Children's Hospital, treatment of leg length discrepancy is a common procedure. Historically, this has been done with external fixators. With the development in intramedullary technology, internal nails have become the preferred modality for long bone lengthening in the adolescent population. However, it is important to review whether this technology practically reduces the known challenges seen and if it brings any new issues. Therefore, the aim of this review is to retrospectively evaluate the therapeutic challenges of 16 fit-bone intramedullary femoral lengthening's at Sheffield Children's Hospital between 2021–2022.Materials & MethodsThe international classification of function (ICF) framework was used to differentiate outcomes. The patient's therapy notes were retrospectively reviewed for themes around structural, activity and participation limitation. The findings were grouped for analysis and the main themes presented.ResultsThere were 8 males, mean age 17.4 years (range 17–18) and 8 females, mean age 15.9 years (range 14–18). 5 right and 11 left femurs were lengthened. Underlying pathology varied amongst the 16 patients. All patients went into a hinged knee brace post operatively. Structural limitations included: pain, fixed flexion deformity of the knee, loss of knee flexion, quadriceps muscle lag, muscle spasms and gluteal weakness. The primary activity limitation was reduced weight bearing with altered gait pattern. Participation limitations included reduced school attendance and involvement in activities with peers. Access to Physiotherapy from local services varied dramatically. Five of the cohort have completed treatment.ConclusionsAnecdotally, intramedullary femoral lengthening nails have perceived benefits for families compared to external fixators in the adolescent population. However, there remain musculoskeletal and psychosocial outcomes requiring therapeutic management throughout the lengthening process and beyond. Therefore, quantifying these outcomes is essential for measuring the impact on each patient for comparison. To interpret these themes, we need to evaluate the outcomes objectively, this was not done consistently in this review. Future research should look at outcome measures that are sensitive to all aspects of the ICF. With an aim of improving the therapeutic treatment provided and the overall outcome for the children treated.

Seismic Assessment of Combined Effects of Knee Bracing and Dog-bone Connections in Dual Moment Frame Systems for Tall Steel Structures

The growing population and urbanization have led to an increasing interest in constructing tall buildings, particularly in large cities. However, the frequent occurrence of earthquakes worldwide has necessitated the development of systems with high ductility and sufficient lateral stiffness. The special dual system of moment frame with bone connections and knee bracing systems are two examples of such systems. In this study, the seismic behavior of these two systems in combination with tall structures was investigated. Ten, thirteen, and sixteen-story frames with four different combinations of bone joints and knee bracing were analyzed using ETABS software. Linear and nonlinear static (pushover) analyses, as well as linear and nonlinear dynamic (time history) analyses, were conducted. Seismic parameters were then calculated for each case and compared. The results emphasized the importance of considering multiple factors and coefficients when evaluating the seismic performance of structures.

Osteophyte-related medial collateral ligament injury in asymptomatic osteoarthritis following minor trauma: a case report.

A 78-year-old Thai female presented with left knee pain 1h after a low-energy trauma caused by a fall. The MRI showed deep MCL and medial meniscal root injuries, a nondisplaced lateral femoral condyle, and also revealed a large osteophyte near the midpart of the MCL, with a blunt persistent projection from the osteophyte pushing against the MCL where the injury was located. She was treated with a knee brace, a gait aid for walking, and analgesic pain control. Her symptoms gradually improved over the next few weeks. If an osteophyte touches a ligament, it can cause degenerative changes to the ligament from chronic irritation, resulting in reducing the strength of the ligament and may be causing some degree of degenerative changes and tightening of the MCL in its at-rest state, resulting in an increased chance of injury when it is required to resist a sudden external force, even from a minor trauma. When there is an osteophyte pushing against a ligament, there is an increased chance of ligament injury when even a minor trauma stresses that ligament.

The description of knee brace interventions for knee osteoarthritis: a review of published randomised controlled trials

The description of knee brace interventions for knee osteoarthritis: a review of published randomised controlled trials

Combined Rehabilitation Protocol in the Treatment of Osteoarthritis of the Knee: Comparative Study of Extremely Low-Frequency Magnetic Fields and Soft Elastic Knee Brace Effect.

The investigation of this observational case-control study aimed at determining the effectiveness of a combined treatment of extremely low-frequency electromagnetic fields (ELF) with a soft elastic knee brace versus ELF alone in knee osteoarthritis (KOA) with respect to a reduction in pain and functional recovery. We hypothesized that the combined use of ELF and a soft elastic knee brace may provide better results. Thirty-five patients (N = 35, divided into Group 1 = ELF and Group 2 = ELF with the soft elastic knee brace) were analyzed. The rehabilitative protocol consisted of 10 sessions of antiphlogistic and antiedema programs (first cycle) for 2 weeks, followed by twelve sessions of bone repair and connective tissue repair programs (second cycle) in patients with knee osteoarthritis (KOA) for 4 weeks. Patient evaluations were conducted at baseline (T0) and after 2 (T1) and 4 (T2) weeks of treatment. A follow-up evaluation was conducted 6 weeks after treatment (T3). The LIMFA© Therapy System was used to create multifrequency magnetoelectric fields with an intensity of 100 µT and a low-frequency field. The Incrediwear Cred 40 knee sleeve (Incred) was used for alleviating knee pain. The Visual Analogue Scale (VAS), the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Lysholm score (Ls) were used as outcome measures. The results showed that pain at rest (Vr), pain in motion (Vm), KOOS, and Ls were significantly affected by ELF over time. In conclusion, Group 2 had a better response in terms of pain resolution at rest (p < 0.05) and a concurrent better response at T3 in terms of functional recovery (p < 0.05).

Analysis of a Motocross Knee Brace: From the Real Model to the Numerical Finite Element Model via 3D Scanning and Reverse Engineering

Musculoskeletal injuries often occur when performing motocross; almost half of the overall ligamentous injuries (42%) are knee ligaments injuries. Lesions can be greatly reduced with knee braces. Commercial knee braces are expected to oppose and limit unwanted and potentially harmful movements such as hyperextension and excessive rotation of the knee joint. However, this aspect has not been fully investigated from a biomechanical point of view. This would require proper Finite Element Modelling (FEM) and Analysis (FEA). However, to perform FEA and evaluate the efficacy of the brace simulating sportive conditions, numerical models need to be built. It requires a dedicated setup and several preprocessing steps, for which no industrial standard or widely accepted better practise is available as of today. Firstly, the brace and the lower limb are scanned using a 3D scanner. The geometry is reconstructed using reverse engineering techniques. These allow us to obtain a smooth, reliable 3D model starting from the points cloud acquired during scanning. A lower limb model was created using a mixed approach, combining MRI data and 3D scanning. Finally, a simulation of the impact condition after a jump using the developed model was carried out.

Center of Pressure Deviation during Posture Transition in Athletes with Chronic Ankle Instability.

Center of pressure (COP) tracking during posture transition is an ideal scale for determining the recurrence of an ankle injury, thereby preventing chronic ankle instability (CAI). However, the same is difficult to determine because the reduced ability of certain patients (who experienced sprain) to control posture at the ankle joint is masked by the chain of hip and ankle joint motion. Thus, we observed the effects of knee joint immobilization/non-immobilization on postural control strategies during the posture transition task and attempted to evaluate the detailed pathophysiology of CAI. Ten athletes with unilateral CAI were selected. To examine differences in COP trajectories in the CAI side and non-CAI legs, patients stood on both legs for 10 s and one leg for 20 s with/without knee braces. COP acceleration during the transition was significantly higher in the CAI group with a knee brace. The COP transition from the double- to single-leg stance phase was significantly longer in the CAI foot. In the CAI group, the fixation of the knee joint increased COP acceleration during postural deviation. This suggests that there is likely an ankle joint dysfunction in the CAI group that is masked by the hip strategy.

Tricompartment offloader knee brace reduces sagittal plane knee moments, quadriceps muscle activity, and pain during chair rise and lower in individuals with knee osteoarthritis

The Levitation tricompartment offloader (TCO) knee brace provides an assistive knee extension moment with the goal of unloading all three compartments of the knee and reducing pain for individuals with multicompartment knee osteoarthritis (OA). This study aimed to determine the effect of the TCO brace on sagittal plane knee moments, quadriceps muscle activity, and pain in individuals with multicompartment knee OA. Lower limb kinematics, kinetics, and electromyography data were collected during a chair rise and lower to determine differences between bracing conditions. TCO brace use significantly decreased the peak net knee external flexion moment in high power mode, providing extension assistance during chair rise [p<0.001; mean difference (MD) (98.75% CI) -0.8 (-1.0, -0.6)%BWxH] and bodyweight support during chair lower [p<0.001; -1.1 (-1.6, -0.7)%BWxH]. Quadriceps activation intensity was significantly reduced with brace use by up to 67% for the vastus medialis [Z = -2.55, p = 0.008] and up to 39% for the vastus lateralis [Z = -2.67, p = 0.004]. Participants reported significantly reduced knee pain with the TCO brace worn in high power mode compared to the no brace condition [p = 0.014; MD (97.5% CI) -18.8 (-32.22, -2.34) mm]. These results support the intended mechanism of joint unloading via extension assistance with the TCO brace. The observed biomechanical changes were accompanied by immediate reductions in user reported pain levels, and support the use of the TCO for conservative management to reduce knee pain in patients with multicompartment knee OA.

Is arthroscopic assisted double tibial tunnel fixation a good option for tibial eminentia fractures?

Tibial eminentia fractures are avulsion fractures of the anterior cruciate ligament caused with additional injuries like meniscus tears or ligamentous injuries. Arthroscopic assisted internal fixation has become a preferred technique with the development of arthroscopic techniques. We aimed to present our results for arthroscopic assisted double tibial tunnel fixation in patients with displaced eminentia fracture. Twenty patients who were operated on for eminentia fracture between January 2010 and May 2014 were included in this study. All fractures were type II according to Meyers's classification. Eminentia was reduced with two nonabsorbable sutures through the ACL. Two tibial tunnels were created over the medial proximal tibia with a 2.4 mm cannulated drill. The two suture ends taken out of the 2 tibial tunnels were connected on the bone bridge between the tunnels. Patients were evaluated with Lysholm score, Tegner score, IKDC score and examined for clinical and radiological evidence of bony union. Quadriceps exercises were started on the third day. The patients were followed up with a locked knee brace in extension for 3 weeks after surgery and later patients were encouraged to mobilize as pain allowed. The preoperative Lysholm score was 75 ±3.3 and the postoperative Lysholm score was 94.5 ±3. Tegner score was 3.52±1.02 preoperatively and 6.84±1.099 postoperatively. International Knee Documentation Committee(IKDC) score was abnormal in all of the 20 patients preoperatively but normal postoperatively. The postoperative scores of the patients were statistically significant when compared with preoperative activity scores(p<0,0001). Tibial eminentia fractures may lead to pain, knee instability, malunion, laxity, or extension deficit. The technique we have described together with early rehabilitation may give good clinical results.

Tricompartment offloader knee brace reduces contact forces in adults with multicompartment knee osteoarthritis.

The levitation tricompartment offloader (TCO) brace is designed to unload all three knee compartments by reducing compressive forces caused by muscle contraction. This study aimed to determine the effect of the TCO on knee contact forces and quadriceps muscle activity in individuals with knee osteoarthritis. Lower limb kinematics, kinetics, and electromyography data were collected during a chair rise-and-lower task. A three-dimensionalinverse dynamics model of the lower leg and foot was used with a sagittal plane knee model to compute knee joint forces. TCO brace use significantly decreased forces in the tibiofemoral [p = 0.001; mean difference,MD (97.5% confidence interval,CI) -0.62 (-0.91, -0.33) body weight (BW)] and patellofemoral [p = 0.001; MD (97.5% CI) -0.88 (-1.36, -0.39) BW] compartments in high-power mode. Significant reductions in quadriceps tendon force [p = 0.002; MD (97.5% CI) -0.53 (-0.83, -0.23) BW] and electromyography intensity of the vastus medialis [p = 0.018, MD (97.5% CI) -30.7 (-59.1, -2.3)] and vastus lateralis [p = 0.012, MD (97.5% CI) -26.2 (-48.5, -3.9)] were also observed. The TCO significantly reduced tibiofemoral and patellofemoral contact forces throughout chair lower, and when knee flexion was greater than 50° during chair rise in high power. These results demonstrate that the TCO reduces contact forces in the tibiofemoral and patellofemoral joint compartments and confirms that the TCO unloads the joint by reducing compressive forces caused by the quadriceps. Clinical significance: The magnitude of knee joint unloading provided by the TCO is similar to that achieved by clinically recommended levels of bodyweight loss and is therefore expected to result in clinical benefits for knee osteoarthritis patients.

Immediate effects of a buffered knee orthosis on gait in stroke patients with knee hyperextension.

Patients exhibit considerable variations in gait patterns especially in knee hyperextension in the stance phase after stroke. If knee hyperextension is untreated it may lead to pain, reduced independence in activities of daily living, deformities and instability. The aim of this study was to investigate the immediate effects of a buffered knee orthosis on gait of stroke patients with knee hyperextension. A total of nine patients with knee hyperextension after stroke were selected to wear buffered knee orthosis developed by Zhongshan Traditional Chinese Medicine Hospital and Ruike Medical Technology (Shanghai) Co., Ltd during walking training and daily walking. Then the gait analysis system of Motionanalysis was used to analyze and evaluate kinematic and spatiotemporal parameters of the gait in patients with independent walking or walking with a buffered knee orthosis. After wearing the buffered knee brace, initial contact, maximum and minimum angles of support phase, the toe off the ground, maximum and minimum angles of swing phase on the injured side of knee and ankle increased. Minimum angle of support phase and maximum angle of swing phase on the uninjured side of ankle decreased, while the toe off the ground and minimum angles of swing phase increased significantly (all P< 0.05); There was no significant difference in other kinematics, in parameters between time and space, in walking speed among subjective gait parameters (P> 0.05). Walking distance, confidence, sense of security, and the feeling of walking hyperextension were all improved. In addition, the number of asymmetric kinematic parameters and spatiotemporal parameters decreased. The buffered knee orthosis can effectively prevent knee hyperextension after stroke, improve the knee and ankle sagittal motion, gait asymmetry, gait subjective feeling, and does not affect gait space-time parameters.

Seismic performance evaluation and design of resilient knee braced frames equipped with shape memory alloy knee braces and replaceable energy-dissipating connections

This paper proposes a novel seismic resilient knee braced frame (KBF) and focuses on seismic performance evaluation and design. In this novel system, the shape memory alloy (SMA) knee braces (KBs) and replaceable energy-dissipating (RED) connections are the key components. The SMA KBs mainly provide self-centering capacity, and the RED connections mainly offer energy-dissipating capacity. To reveal the seismic performance characteristics, the 3- and 6- story KBFs are selected as the example structures. The proposed systems are designed by a modified performance-based plastic design method, which distributes the seismic energy to the SMA KBs and the RED connections by defining an energy distribution factor p. In what followed, nonlinear static and nonlinear time history analysis are conducted. It indicates that these systems could well meet the prescribed performance targets, although they are designed using different p values. In current work, the potentially optimal p value is found to be 0.1, which represents the case where 10% of seismic energy is allocated to the SMA KBs. The advantages of the novel KBF are twofold: 1) the consumption of SMA material is significantly reduced, because the RED connections are the major damping source; 2) the damaged RED connections can be conveniently repaired or replaced, because the frames could nearly return to original position, owing to the SMA KBs.