Design and Development of an Instrumented Knee Joint for Quantifying Ligament Displacements

Recently robotic assistive leg exoskeletons have gained popularity because an increased number of people crave for powered devices to run faster and longer or carry heavier loads. However, these powered devices have the potential to impair knee ligaments. This work was aimed to develop an instrumented knee joint via rapid prototyping that measures the displacements of the four major knee ligaments\textemdash the anterior cruciate ligament (ACL), posterior crucial ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL)\textemdash to quantify the strain experienced by these ligaments. The knee model consists of a femur, lateral and medial menisci, and a tibia-fibula, which were printed from 3D imaging scans. Non-stretchable cords served as main fiber bundles of the ligaments with their desired stiffnesses provided by springs. The displacement of each cord was obtained via a rotary encoder mechanism, and the leg flexion angle was acquired via a closed-loop four-bar linkage of a diamond shape. The displacements were corroborated by published data, demonstrating the profiles of the displacement curves agreed with known results. The paper shows the feasibility of developing a subject-specific knee joint via rapid prototyping that is capable of quantifying the ligament strain via rapid prototyping.

A COMPARISON OF SOME ANTHROPOMETRIC AND MOTOR FEATURES OF VISUALLY IMPAIRED STUDENTS WHO PLAY SPORTS AND THOSE WHO DO NOT PLAY SPORTS IN SCHOOLS FOR THE VISUALLY IMPAIRED IN TURKEY

Purpose: The aim of this study is to compare certain anthropometric and motor features of visually impaired students who play sports and those who do not play sports in schools for the visually impaired in Turkey. It is thought that the sport has an important place in the rehabilitation of disabled people and also has an effect on their physical characteristics. Material and Methods: In this context, 98 visually impaired students who played sports regularly (72 male, 26 female) and 189 visually impaired students who did not play sports regularly (110 male, 79 female) participated in our study. In the study, participants’ gender, age, height, body weight, body mass index, girth, and motor features such as flamingo balance test, flexibility, standing long jump, sit-up, bent arm hang, 10 x 5m shuttlerun, grip strength, vertical jump, abdominal strength, back strength, hip flexion strength, hip extension strength, leg flexion strength, leg extension strength, arm strength and arm extension strength were measured. During the strength measurements, Lovett’s Manual Muscle Strength Test was utilised. Results: In the study, significant differences were found between visually impaired students who played sports and those who did not play sports in terms of age, height, grip strength, vertical jump, balance test, flexibility, long jump, sit-up, bent arm hang, 10 x 5m shuttle run, abdominal strength, back strength, hip flexion strength, hip extension strength, leg flexion strength, leg extension strength, arm flexion strength and arm extension strength (p<0.05). However, no significant differences were found in terms of body weight, body mass index or girth (p>0.05). Conclusion: Examination of the test results of the study reveals that visually impaired students who played sports had higher performance levels than those of students who did not play sports. It is recommended that visually impaired students, as well as being given physical education lessons, should take part in more mobility games and sporting activities, or that more mobility games and sporting activities should be included in course curricula. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0740/a.php" alt="Hit counter" /></p>

The Effects of Short-Term Visual Feedback Training on the Stability of the Roundhouse Kicking Technique in Young Karatekas

The aim of this study was to assess the efficacy of using real-time visual feedback (VF) during a one-week balance training intervention on postural sway parameters in young karatekas. Twenty-six young male karatekas (age = 14.0 ± 2.3 years) were randomly divided into two groups: real-time VF training (VFT; n = 14) and control (CTRL; n = 12). Their center of pressure (COP) displacement (path length, COPpl; distance from origin, COPod) was assessed pre- and post-training on a Wii Balance Board platform in two positions (Flex: knee of the supporting leg slightly bent, maximum hip and leg flexion of the other leg; Kick: knee of the supporting leg slightly bent, mawashi-geri posture for the kicking leg). Both groups trained twice a day for seven days, performing a one-legged stance on the non-dominant limb in the Kick position. During the training, VFT received real-time VF of COP displacement, while CTRL looked at a fixed point. No interaction effect was found (p > 0.05). VFT exhibited greater changes pre- and post-training in Flex COPpl (−25.2%, g = 1.5), Kick COPpl (−24.1%, g = 1.3), and Kick COPod (−44.1%, g = 1.0) compared to CTRL (−0.9–−13.0%, g-range: 0.1–0.7). It is possible that superimposing real-time VF to a week-long balance training intervention could induce a greater sport-specific balance-training effect in young karatekas.

Experimental quantification of soft tissue deformation in quasi-static single leg flexion using biplanar imaging

Soft tissue deformation(STD) causes the most prominent source of error in skin marker (SM) based motion analysis, commonly referred to as Soft Tissue Artifact (STA). To compensate for its effect and to accurately assess in vivo joint kinematics, quantification of STD in three-dimension (3D) is essential. In the literature, different invasive and radiological approaches have been employed to study how STA propagates in joint kinematics. However, there is limited reference data extensively reporting distribution of the artifact itself in 3D.The current study was thus aimed at quantifying STD in 10 subjects along three anatomical directions. Biplanar X-ray system was used to determine true bone and SM positions while the subjects underwent quasi-static single leg flexion.STD exhibited inter-subject similarity. A non-uniform distribution was observed at the pelvis, thigh and shank displaying maximum at the thigh (up to 18.5 mm) and minimum at the shank (up to 8 mm). STD at the pelvis and thigh displayed inter-marker similarity. STD at the pelvis was found direction independent, showing similar distribution in all the 3 directions. However, the thigh and shank exhibited higher STD in the proximal-distal direction of the bone embedded anatomical reference frame. These findings may provide more insights while interpreting motion analysis data as well to effectively strategize STA compensation methods.

IMPROVED PHYSICAL FUNCTION WITH COMPLEMENTARY USE OF A DIETARY SUPPLEMENT FOR MILD KNEE OSTEOARTHRITIS: A SUBGROUP ANALYSIS

The aim: In this study, we present a sub-analysis of physical functionality in sufferers of mild knee osteoarthritis (OA) following a clinical assessment of a novel nutraceutical supplement Tregocel® complementary to standard treatment. Materials and methods: We evaluated the results of a multicenter, open-label, single-arm efficacy and safety evaluation of a polyherbal nutraceutical, performed in subjects with symptomatic, mild knee OA (n = 107, 59.7 ± 10.8 yrs, 68.2% female) over 36 weeks. Physical function was assessed using a standardized walking challenge (6-min walk test), combined with WOMAC indices and leg flexion measurements. Sub-analysis was performed using a linear mixed model that tracked changes in the walking challenge outcomes over time, adjusted for age, gender, and OA duration. Results: Walking distance was significantly improved with the duration of nutraceutical use, increasing by 0.72 m (95% CI: 0.56, 0.88) per week of product administration. Similarly, there were significant decreases in WOMAC indices per week for stiffness (-1.6, 95% CI: -1.8, 1.4), daily functioning (-13.5, 95% CI: 14.9, 11.9) and global outcome (-19.2, 95% CI -21.3 – -17.1). Furthermore, supine heel-to-high flexion distance was improved relative to the duration of nutraceutical use. Conclusions: The use of a polyherbal nutraceutical resulted in clinical improvements in several indices of physical functioning in mild knee OA suffers. Trial registration: NCT03636035

Metabolic Power and Efficiency for an Amputee Cyclist: Implications for Cycling Technique

Cycling technique is steeped in cultural lore. One deeply held belief is that "pulling-up" to lift the leg (increased muscular leg flexion) will optimize technique and improve efficiency. In contrast, scientific evidence suggests that when cyclists are instructed to pull-up efficiency decreases. However, such interventions may not have allowed sufficient time for cyclists to adapt and refine their technique. This case study documented how a cyclist with a complete unilateral limb amputation consumed metabolic power to produce mechanical power during single-leg cycling. The cyclist was a 4-time U.S. National Paralympic Champion who performed single-leg cycling for 7yrs and thus was fully adapted to pull-up. We hypothesized that a counterweight system, which reduced the requirement to pull-up, would decrease metabolic power and increase efficiency for this cyclist. The cyclist performed submaximal cycling (100, 135, 170, 205W, 80rpm, 5min) with and without a counterweight (10kg) on the unused crank. Expired gasses were measured, and metabolic power and gross efficiency were calculated. Metabolic power decreased on average by 87±7W (p<0.001) and gross efficiency increased from 16.3±1.9 to 18.0±1.8% (p<0.001) when cycling with the counterweight. During counterweighted single-leg cycling, the metabolic power of unloaded cycling decreased (317 vs. 238W) and delta efficiency was similar (25.2 vs. 25.5%). Results demonstrated that significant metabolic power was associated with pulling-up to produce muscular leg flexion power even in a cyclist who pulled-up substantially during cycling. Our findings confirm observations from previous studies that altered pedaling technique acutely and indicate that pulling-up during cycling is less efficient.

Dynamics of carving runs in alpine skiing. II.Centrifugal pendulum with a retractable leg.

In this paper we present an advanced model of centrifugal pendulum where its length is allowed to vary during swinging. This modification accounts for flexion and extension of skier's legs when turning. We focus entirely on the case where the pendulum leg shortens near the vertical position, which corresponds to the most popular technique for the transition between carving turns in ski racing, and study the effect of this action on the kinematics and dynamics of these turns. In particular, we find that leg flexion on approach to the summit point is a very efficient way of preserving the contact between skis and snow. The up and down motion of the skier centre of mass can also have significant effect of the peak ground reaction force experienced by skiers, particularly at high inclination angles. Minimisation of this motion allows a noticeable reduction of this force and hence of the risk of injury. We make a detailed comparison between the model and the results of a field study of slalom turns and find a very good agreement. This suggests that the pendulum model is a useful mathematical tool for analysing the dynamics of skiing.

The effect of combined preconditioning strategies on isokinetic strength in well trained kickboxers

Background & Study Aim: The use of preconditioning strategies (PconSt) alone has a positive impact on performance. However, it is thought that there will be more impact on the performance of the combined preconditioning strategies, and this is the first work to prove it. This study was to examine the effect of combined preconditioning strategies on isokinetic strength in well-trained kickboxers. Material & Methods: The following preconditioning strategies were combined: morning resistance exercise (MRE), ischemic preconditioning (IP), active warm-up (AW-U), hormonal preconditioning (HP) and post-activation potentiation (PAP). Fifteen well-trained male kickboxers (age: 22.38 ± 4.01years, height: 182.23 ± 1.05cm, body mass: 77.67 ± 8.01kg) volunteered for this study. Peak isokinetic knee extension and flexion moment were determined at 60°/s, 180°/s and 240°/s bilaterally. All participants performed the pre-test and then were randomly divided into Sham and PconSt groups on separate days. For the PconSt group, MRE, IP, AW-U, HP and PAP were implemented sequentially before test. Results: The findings indicated significant increase in strength after combined training in the PconSt groups for right leg flexion at 180°/s flexion (p < 0.05). The average percentage strength difference between sham and PconSt groups was 4.12 ± 8.95%. Conclusionː This study showed that a combined preconditioning strategy increased isokinetic strength.

The influence of the position of the medial portal and of lower leg flexion on the length of the femoral tunnel in anatomic anterior cruciate ligament reconstruction: A cadaveric study

Background/Aim. The key to successful anterior cruciate ligament reconstruction lies in the proper positioning of the femoral tunnel within the anatomical footprint and in providing for an adequate length of this tunnel without perforation to the lateral cortex. The aim of this study was to determine the change in the length of the femoral tunnel drilled during anatomic anterior cruciate ligament (ACL) reconstruction, depending on: the position of the limb being operated on, the degree of knee flexion, as well as the angle between the drill and the medial aspect of the lateral condyle. Methods. This study was performed on 16 cadaveric knees (6 male and 10 female) of the average age of 83. After the subcutaneous tissue was dissected, the femoral insertion of the ACL was identified. Then, 18 tunnels were drilled through the center of the femoral insertion with the help of 2 mm thick Kirschner wires. This was performed in two stages. In the first phase the leg was positioned on an arthroscopic leg holder, while in the second phase the leg was positioned on the table. In each phase the knee was placed in three different flexion positions (110?, 120? and 130?) and for each position three tunnels were drilled (70?, 60? and 50?) in relation to the medial aspect of the lateral condyle. Results. The average length of the femoral tunnel drilled with the leg positioned on the operating table (36.6 ? 4.7 mm) was highly statistically significantly greater (p = 0.000) in comparison with the length of the femoral tunnel obtained by positioning the leg on a fixed arthroscopic leg holder (35.4?4.3 mm). The greatest lengths of the femoral tunnel were obtain with the leg flexed at 130? and the reamer positioned at 50? angle in relation to the medial aspect of the lateral condyle (43 mm on the operating table and 41 mm on a fixed leg holder), while the shortest tunnel (33 mm on the operating table and 31 mm on a fixed leg holder) was obtained with the lower leg flexed at 110? and the reamer positioned at a 70? angle. Conclusion. The optimal position of the leg on a fixed leg holder for obtaining a femoral tunnel of sufficient length requires lower leg flexion of 120? and the position of the medial portal which enables the positioning of the reamer at a 60? angle in relation to the medial aspect of the lateral condyle. With the leg positioned on the operating table, it becomes unnecessary to push the leg into flexion greater than 110?; rather a longer femoral tunnel is achieved by lateralization of the medial portal.