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Research on dynamics of the knee joint for different types of loads

Research on dynamics of the knee joint for different types of loads Modern clinical and sports medicine increasingly uses training and diagnostic equipment. They allow monitoring of the training process, cycle control, and evaluation of the basic parameters. These devices are used to carry out the training process for healthy people as well as for the rehabilitation of persons with impaired organ movement functions. The developed measurement properties allow defining many parameters and biomechanical functions. They can estimate the state of a particular biomechanical group and monitor its efficiency for a long period of time. The main aim of the research was to determine the impact of the type of load on the dynamic parameters during straightening of the knee joint. It compared parameters of the sick and healthy limbs under the influence of a particular load. The article presents the results of measurements of dynamic parameters of the knee joint. Measurements were obtained during the use of different types of loads for healthy people. The second part of the article concerns the comparison of functions in the sick and healthy limbs of the test person. Keywords: biomedical engineering; medical biology; medical science. Introduction Modern clinical and sport medicine has been increasingly employing training and diagnostic tools. This allows monitoring of the training process, setting variable loads, applying control over the effort cycle, and assessing the basic parameters. These devices are used for managing the training process for healthy persons, and may also be successfully used in the rehabilitation of persons with impairment of motor organ functionalities. The extensive *Corresponding author: Jacek Dygut, The Regional Hospital St. Padre Pio, ul. Monte Cassino Przemyl, Poland, E-mail: jacekdygut@gmail.com Marek Kuchta: Department of Electronic, Military University of Technology, Warszawa, Poland measurement possibilities allow setting a number of parameters and biomechanical functions used for the assessment of the condition of a given biomechanical system, and monitoring of changes in its capacity over an extended period of time [1­4]. Both training and improvement of the joint and muscular systems consist in the execution of movements of the same type. In case of the knee joint, these are extension or flexion movements of the lower leg with overcoming of the preset resistance moment [5, 6]. Sports training differs from improvement training in the selection of loads and effort cycles, as well as the adopted measurement method [7, 8]. The presented measurements for healthy persons were based on the minimum time criterion (covering a section of the road in the shortest time possible). For persons with an injured knee joint, the obtained basic values of parameters and biomechanical functions measured for the affected limb were referred to the same parameters measured for the healthy limb. The main objective of the measurements was to determine the effect of the type of load on dynamic parameters of extension movement in the knee joint, as well as to compare the parameters of the affected limb and of the healthy limb under the specific load. This article features the results of the measurements of parameters of extension dynamics in the knee joint obtained with various types of loads as obtained with healthy persons. The second part of the article reports comparisons of movement between the affected limb and the healthy limb of the examined person. Conditions and methodology of examining healthy persons The study was conducted in a special post fitted with various types of weights in the form of weights over a pulley, a pendulum, rubber strips, and a hydraulic generator of resistance moment [9­11]. Selection of safe values of weights for their types, which would allow complete extension, was a very important issue, which is why three degrees of each weight value were set, with similar values of the weight set for each degree within the ranges presented in Table 1. 250Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads Table 1:Values of external loads used in testing the dynamics of extension in the knee joint. Method of generating moment of the force load Weights, Nm Load level I II III 35 50 75 Pendulum, Nm 35 50 ­ Rubber, Nm 35 50 75 Hydraulic generator, Nm 35 50 75 Sample results of tests with healthy persons Examples of measurements of waveform torque, joint angle, and rotational speed for the first examined person using different types of loads (gravity ballast or hydraulic ballast) are shown in Figures 2 and 3. To compare the results, a set of parameters of the cycle of lower limb straightening of the knee were adopted: Mmax [Nm] ­ maximum moment of the force, t(Mmax) ­ time of maximum moment of the force, (Mmax) ­ angle of maximum moment of the force, Text ­ time of maximal knee extension, max ­ maximum angular velocity, t(max) ­ time of maximum angular velocity, (max) ­ angle of maximum angular velocity, max ­ maximum angular acceleration, t(max) ­ time of maximum angular acceleration, (max) ­ angle of maximum angular acceleration, -max ­ maximum of negative angular acceleration. Comparison of selected parameters obtained for various types of loads, e.g. weights (W), a pendulum (P), a hydraulic generator (H), and rubber (R), is presented in Table 2. The study as well as the opinions of the examined persons indicate that changes in the type of load changes the comfort level of exercises. The least comfortable and safe turned out to be loads of the inertia type: weights and pendulum. They are also cumbersome in the selection of the load. The more comfortable and safe loads were rubber and particularly the hydraulic system. The hydraulic load turned out to be the most stable throughout the range of angular movement. This is confirmed by the torque characteristics shown in Figure 3. On the basis of the studies, the impact of the type of load on movement parameters was found. As shown in Table 2, for each of the examined persons, a number of characteristic parameters exhibited the same features: ­ The greatest maximum moment of extension occurred for the rubber load ­ (185÷108) [Nm]. ­ The lowest maximum moment of extension occured for the hydraulic generator ­ (86÷79) [Nm]. ­ The shortest time of maximum moment occurrence (0.10÷0.11) [s], with the slightest angle (5.2÷6.6) [°], was obtained for rubber. ­ The longest time of maximum moment (0.29÷0.46) [s], with the greatest angle (19÷38) [°], was obtained for the hydraulic generator. ­ The longest time of full extension (1.3÷2.1) [s] occured for the hydraulic generator. The control group included four healthy men. The study was conducted in a stand presented in Figure 1. This stand allows diagnostics and training of the lower limb during its extension and flexion in the knee joint, with the load in the form of a fixed moment of force with various types of load [12, 13]. Before starting the study, the participants were briefed about the measurement stand and the method of execution of the study. The measurement method consisted in extending the lower limb in the knee joint within the shortest time possible. Several tests were done for each degree of load, with a break of 3 min between tests. Change of the load type was done after a 2-h break. Figure 1:The stand for testing the dynamics of knee joint movement. Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads251 Figure 2:Sample results of measurements for one of the subjects with a gravitational weight. Figure 3:Sample results of measurements for one of the subjects with a hydraulic weight. Table 2:The mean values of the characteristic parameters of the cycle of straightening received by all tested persons for various types of loads. Mmax, Nm t(Mmax), s (Mmax), ° Text, s max, °/s t(max), s (max), ° max, °/s2 t(max), s (max), ° max, °/s2 Person 1 H R 86 0.37 38 1.34 238 0.40 45.2 2437 0.16 2.5 1670 110 0.11 6.6 0.40 420 0.24 50 4200 0.12 8 3800 Person 2 H R 79 0.29 19 2.10 146 0.28 17.4 1312 0.14 2.5 1193 104 0.10 6.1 0.38 380 0.22 46 4200 0.10 6.2 3900 Person 3 H R 84 0.34 26.1 1.62 194 0.44 44.7 1465 0.26 12 1585 107 0.10 6.5 0.4 378 0.24 42 3500 0.10 6.1 3600 Person 4 W 105 0.29 7.6 0.64 330 0.49 55 1615 0.31 9.1 2125 P 108 0.26 16.8 0.66 238 0.38 43 1105 0.21 10 1275 H 81 0.46 35 1.30 186 0.47 39 1398 0.24 4.8 1278 R 98 0.10 5.2 0.45 346 0.25 44 2720 0.11 6.4 3600 W 131 0.13 9.4 0.37 403 0.26 51 2635 0.13 9.9 2890 P 185 0.16 9.3 0.52 282 0.27 35 1700 0.16 11.1 2295 W 126 0.14 7.8 0.41 358 0.28 50 2295 0.13 7.4 3315 P 157 0.11 7.8 0.50 280 0.22 40 1360 0.19 6.3 1190 W 110 0.20 11.4 0.48 338 0.36 57 1870 0.19 9.6 2295 P 126 0.19 9.0 0.62 248 0.34 42 1275 0.18 7.7 1105 W, Weights; R, rubber; P, pendulum; H, hydraulic generator; Mmax [Nm], maximum moment of the force; t(Mmax), time of maximum moment of the force; (Mmax), angle of maximum moment of the force; Text, time of maximal knee extension; max, maximum angular velocity; t(max), time of maximum angular velocity; (max), angle of maximum angular velocity; max, maximum angular acceleration; t(max), time of maximum angular acceleration; (max), angle of maximum angular acceleration; -max, maximum of negative angular acceleration. The highest speed of extension (346÷420) [°/s] was obtained for the rubber load, and the lowest (146÷238) [°/s] for the hydraulic generator. For inertia loads as weights (W) and pendulum (P), full extension was obtained with the speed significantly greater than zero, which is disadvantageous for the 252Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads safety of the examined person. In conclusion, it could be said that the most favorable in terms of unconditional safety and comfort for the exerciser is the hydraulic weight. With hydraulic load, the lowest moment developed by the lower limb was obtained, whereas the time it took to reach the maximum value is the longest of all the types of loads. It confirmed the measurements presented in the article as well as the personal opinions of the examined persons. Hydraulic load is recommended for training persons with mobility problems and the elderly. with four different injuries subject to hospital treatment. The patients underwent a series of measurements with a hydraulic weight with fixed resistance moments. The distribution of these loads is presented in Figure 4. During the study, each person performed five tests with identical load for each joint function of the right and left limbs. The following codes were applied: chp, the injured limb in extension; chz, the injured limb in flexion; zp, the healthy limb in extension; zz, the healthy limb in flexion. Movements and exercises were done within the ranges and loads that did not cause discomfort and pain. The sample results of the conducted tests are presented in Figures 4­7. Conditions and methodology of examining patients The presented rehabilitation and diagnostic stand fitted with hydraulic weights may be successfully used for improvement exercises and preliminary tests of persons with an injured knee joint. The tests conducted in this stand are completely safe. It seems that the most valuable method presenting progress in improving the knee joint would be a method based on referring the obtained results to the values achieved in the previous measurement sessions. In the presented tests (owing to their limited duration), a different method was used in which the results obtained for the affected limb were referred to the tests of the same biomechanical values for the healthy limb. The study covered a group of six persons Sample results of tests with patients Each patient should be analyzed separately due to the different weights used. The following part of the text presents selected results of particular biomechanical parameters obtained during the tests of the affected and healthy limbs. The values are expressed in percentages to present the difference in the results between the healthy limb and the injured limb. Irrespective of the type of damage, the speed and power obtained during extension of the injured limb in the knee joint, as presented in Figure 5, were 20%­50% lower than those obtained in the healthy limb. Similar 60 a meniscus a meniscus 1 50 ACL 1 ACL Operating treatment Knee sprain 40 Fmax, Nm chp chz zp zz Figure 4:Average values for external load moments recorded during tests. Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads253 vmax (%) Pmax (%) 0 Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) Figure 5:Percentage values of differences for speed and power during extension in the knee joint. 80 70 60 50 40 30 20 10 0 Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) vmax (%) Pmax (%) Figure 6:Percentage values of differences for speed and power during flexion in the knee joint. vFmax (%) vPmax (%) Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) Figure 7:Movement speed values obtained for the maximum moment of force in the joint (vFmax) and power (vPmax) during extension. 254Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads 70 60 50 40 30 20 10 0 Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) vFmax (%) vPmax (%) Figure 8:Movement speed values obtained for the maximum moment of force in the joint (vFmax) and power (vPmax) during flexion. differences were obtained for flexion, as visualized in Figure 6. Relatively much higher values of the muscle moment and power were found depending on the speed at which the subjects achieved maximum values of these parameters. The results in this case were also higher in case of the healthy limb (Figures 7 and 8). Summary Methods for rehabilitation of the knee and their effects are widely discussed in the literature [14­16]. The results presented in this article justify the conclusion that the type of load has a major effect on the obtained results during tests of the knee joint under kinematic conditions. Inertia weights (weights and pendulum) proved to be least comfortable and safe. Hydraulic weight ensures the highest safety and comfort of the exercise, as it provides the best feeling of stability of load throughout the angular range of movement. When there is no reaction on the part of the subject, the resistance moment in the hydraulic weight fades out. For this reason, this method is specifically indicated for tests and rehabilitation exercises for persons with knee joint injuries. The presented test methods, the minimum time method for healthy persons, and the method based on comparing the results obtained for the injured and healthy lower limbs, proved their effectiveness with the improvement of the condition of the movement organ of the knee joint. Author contributions: All the authors have accepted responsibility for the entire content of the submitted manuscript and approved submission. Research funding: None declared. Employment or leadership: None declared. Honorarium: None declared. Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Bio-Algorithms and Med-Systems de Gruyter

Research on dynamics of the knee joint for different types of loads

Bio-Algorithms and Med-Systems , Volume 11 (4) – Dec 1, 2015

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Abstract

Modern clinical and sports medicine increasingly uses training and diagnostic equipment. They allow monitoring of the training process, cycle control, and evaluation of the basic parameters. These devices are used to carry out the training process for healthy people as well as for the rehabilitation of persons with impaired organ movement functions. The developed measurement properties allow defining many parameters and biomechanical functions. They can estimate the state of a particular biomechanical group and monitor its efficiency for a long period of time. The main aim of the research was to determine the impact of the type of load on the dynamic parameters during straightening of the knee joint. It compared parameters of the sick and healthy limbs under the influence of a particular load. The article presents the results of measurements of dynamic parameters of the knee joint. Measurements were obtained during the use of different types of loads for healthy people. The second part of the article concerns the comparison of functions in the sick and healthy limbs of the test person. Keywords: biomedical engineering; medical biology; medical science. Introduction Modern clinical and sport medicine has been increasingly employing training and diagnostic tools. This allows monitoring of the training process, setting variable loads, applying control over the effort cycle, and assessing the basic parameters. These devices are used for managing the training process for healthy persons, and may also be successfully used in the rehabilitation of persons with impairment of motor organ functionalities. The extensive *Corresponding author: Jacek Dygut, The Regional Hospital St. Padre Pio, ul. Monte Cassino Przemyl, Poland, E-mail: jacekdygut@gmail.com Marek Kuchta: Department of Electronic, Military University of Technology, Warszawa, Poland measurement possibilities allow setting a number of parameters and biomechanical functions used for the assessment of the condition of a given biomechanical system, and monitoring of changes in its capacity over an extended period of time [1­4]. Both training and improvement of the joint and muscular systems consist in the execution of movements of the same type. In case of the knee joint, these are extension or flexion movements of the lower leg with overcoming of the preset resistance moment [5, 6]. Sports training differs from improvement training in the selection of loads and effort cycles, as well as the adopted measurement method [7, 8]. The presented measurements for healthy persons were based on the minimum time criterion (covering a section of the road in the shortest time possible). For persons with an injured knee joint, the obtained basic values of parameters and biomechanical functions measured for the affected limb were referred to the same parameters measured for the healthy limb. The main objective of the measurements was to determine the effect of the type of load on dynamic parameters of extension movement in the knee joint, as well as to compare the parameters of the affected limb and of the healthy limb under the specific load. This article features the results of the measurements of parameters of extension dynamics in the knee joint obtained with various types of loads as obtained with healthy persons. The second part of the article reports comparisons of movement between the affected limb and the healthy limb of the examined person. Conditions and methodology of examining healthy persons The study was conducted in a special post fitted with various types of weights in the form of weights over a pulley, a pendulum, rubber strips, and a hydraulic generator of resistance moment [9­11]. Selection of safe values of weights for their types, which would allow complete extension, was a very important issue, which is why three degrees of each weight value were set, with similar values of the weight set for each degree within the ranges presented in Table 1. 250Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads Table 1:Values of external loads used in testing the dynamics of extension in the knee joint. Method of generating moment of the force load Weights, Nm Load level I II III 35 50 75 Pendulum, Nm 35 50 ­ Rubber, Nm 35 50 75 Hydraulic generator, Nm 35 50 75 Sample results of tests with healthy persons Examples of measurements of waveform torque, joint angle, and rotational speed for the first examined person using different types of loads (gravity ballast or hydraulic ballast) are shown in Figures 2 and 3. To compare the results, a set of parameters of the cycle of lower limb straightening of the knee were adopted: Mmax [Nm] ­ maximum moment of the force, t(Mmax) ­ time of maximum moment of the force, (Mmax) ­ angle of maximum moment of the force, Text ­ time of maximal knee extension, max ­ maximum angular velocity, t(max) ­ time of maximum angular velocity, (max) ­ angle of maximum angular velocity, max ­ maximum angular acceleration, t(max) ­ time of maximum angular acceleration, (max) ­ angle of maximum angular acceleration, -max ­ maximum of negative angular acceleration. Comparison of selected parameters obtained for various types of loads, e.g. weights (W), a pendulum (P), a hydraulic generator (H), and rubber (R), is presented in Table 2. The study as well as the opinions of the examined persons indicate that changes in the type of load changes the comfort level of exercises. The least comfortable and safe turned out to be loads of the inertia type: weights and pendulum. They are also cumbersome in the selection of the load. The more comfortable and safe loads were rubber and particularly the hydraulic system. The hydraulic load turned out to be the most stable throughout the range of angular movement. This is confirmed by the torque characteristics shown in Figure 3. On the basis of the studies, the impact of the type of load on movement parameters was found. As shown in Table 2, for each of the examined persons, a number of characteristic parameters exhibited the same features: ­ The greatest maximum moment of extension occurred for the rubber load ­ (185÷108) [Nm]. ­ The lowest maximum moment of extension occured for the hydraulic generator ­ (86÷79) [Nm]. ­ The shortest time of maximum moment occurrence (0.10÷0.11) [s], with the slightest angle (5.2÷6.6) [°], was obtained for rubber. ­ The longest time of maximum moment (0.29÷0.46) [s], with the greatest angle (19÷38) [°], was obtained for the hydraulic generator. ­ The longest time of full extension (1.3÷2.1) [s] occured for the hydraulic generator. The control group included four healthy men. The study was conducted in a stand presented in Figure 1. This stand allows diagnostics and training of the lower limb during its extension and flexion in the knee joint, with the load in the form of a fixed moment of force with various types of load [12, 13]. Before starting the study, the participants were briefed about the measurement stand and the method of execution of the study. The measurement method consisted in extending the lower limb in the knee joint within the shortest time possible. Several tests were done for each degree of load, with a break of 3 min between tests. Change of the load type was done after a 2-h break. Figure 1:The stand for testing the dynamics of knee joint movement. Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads251 Figure 2:Sample results of measurements for one of the subjects with a gravitational weight. Figure 3:Sample results of measurements for one of the subjects with a hydraulic weight. Table 2:The mean values of the characteristic parameters of the cycle of straightening received by all tested persons for various types of loads. Mmax, Nm t(Mmax), s (Mmax), ° Text, s max, °/s t(max), s (max), ° max, °/s2 t(max), s (max), ° max, °/s2 Person 1 H R 86 0.37 38 1.34 238 0.40 45.2 2437 0.16 2.5 1670 110 0.11 6.6 0.40 420 0.24 50 4200 0.12 8 3800 Person 2 H R 79 0.29 19 2.10 146 0.28 17.4 1312 0.14 2.5 1193 104 0.10 6.1 0.38 380 0.22 46 4200 0.10 6.2 3900 Person 3 H R 84 0.34 26.1 1.62 194 0.44 44.7 1465 0.26 12 1585 107 0.10 6.5 0.4 378 0.24 42 3500 0.10 6.1 3600 Person 4 W 105 0.29 7.6 0.64 330 0.49 55 1615 0.31 9.1 2125 P 108 0.26 16.8 0.66 238 0.38 43 1105 0.21 10 1275 H 81 0.46 35 1.30 186 0.47 39 1398 0.24 4.8 1278 R 98 0.10 5.2 0.45 346 0.25 44 2720 0.11 6.4 3600 W 131 0.13 9.4 0.37 403 0.26 51 2635 0.13 9.9 2890 P 185 0.16 9.3 0.52 282 0.27 35 1700 0.16 11.1 2295 W 126 0.14 7.8 0.41 358 0.28 50 2295 0.13 7.4 3315 P 157 0.11 7.8 0.50 280 0.22 40 1360 0.19 6.3 1190 W 110 0.20 11.4 0.48 338 0.36 57 1870 0.19 9.6 2295 P 126 0.19 9.0 0.62 248 0.34 42 1275 0.18 7.7 1105 W, Weights; R, rubber; P, pendulum; H, hydraulic generator; Mmax [Nm], maximum moment of the force; t(Mmax), time of maximum moment of the force; (Mmax), angle of maximum moment of the force; Text, time of maximal knee extension; max, maximum angular velocity; t(max), time of maximum angular velocity; (max), angle of maximum angular velocity; max, maximum angular acceleration; t(max), time of maximum angular acceleration; (max), angle of maximum angular acceleration; -max, maximum of negative angular acceleration. The highest speed of extension (346÷420) [°/s] was obtained for the rubber load, and the lowest (146÷238) [°/s] for the hydraulic generator. For inertia loads as weights (W) and pendulum (P), full extension was obtained with the speed significantly greater than zero, which is disadvantageous for the 252Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads safety of the examined person. In conclusion, it could be said that the most favorable in terms of unconditional safety and comfort for the exerciser is the hydraulic weight. With hydraulic load, the lowest moment developed by the lower limb was obtained, whereas the time it took to reach the maximum value is the longest of all the types of loads. It confirmed the measurements presented in the article as well as the personal opinions of the examined persons. Hydraulic load is recommended for training persons with mobility problems and the elderly. with four different injuries subject to hospital treatment. The patients underwent a series of measurements with a hydraulic weight with fixed resistance moments. The distribution of these loads is presented in Figure 4. During the study, each person performed five tests with identical load for each joint function of the right and left limbs. The following codes were applied: chp, the injured limb in extension; chz, the injured limb in flexion; zp, the healthy limb in extension; zz, the healthy limb in flexion. Movements and exercises were done within the ranges and loads that did not cause discomfort and pain. The sample results of the conducted tests are presented in Figures 4­7. Conditions and methodology of examining patients The presented rehabilitation and diagnostic stand fitted with hydraulic weights may be successfully used for improvement exercises and preliminary tests of persons with an injured knee joint. The tests conducted in this stand are completely safe. It seems that the most valuable method presenting progress in improving the knee joint would be a method based on referring the obtained results to the values achieved in the previous measurement sessions. In the presented tests (owing to their limited duration), a different method was used in which the results obtained for the affected limb were referred to the tests of the same biomechanical values for the healthy limb. The study covered a group of six persons Sample results of tests with patients Each patient should be analyzed separately due to the different weights used. The following part of the text presents selected results of particular biomechanical parameters obtained during the tests of the affected and healthy limbs. The values are expressed in percentages to present the difference in the results between the healthy limb and the injured limb. Irrespective of the type of damage, the speed and power obtained during extension of the injured limb in the knee joint, as presented in Figure 5, were 20%­50% lower than those obtained in the healthy limb. Similar 60 a meniscus a meniscus 1 50 ACL 1 ACL Operating treatment Knee sprain 40 Fmax, Nm chp chz zp zz Figure 4:Average values for external load moments recorded during tests. Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads253 vmax (%) Pmax (%) 0 Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) Figure 5:Percentage values of differences for speed and power during extension in the knee joint. 80 70 60 50 40 30 20 10 0 Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) vmax (%) Pmax (%) Figure 6:Percentage values of differences for speed and power during flexion in the knee joint. vFmax (%) vPmax (%) Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) Figure 7:Movement speed values obtained for the maximum moment of force in the joint (vFmax) and power (vPmax) during extension. 254Dygut and Kuchta: Research on dynamics of the knee joint for different types of loads 70 60 50 40 30 20 10 0 Meniscus (20 Nm) Meniscus1 (20 Nm) ACL (34 Nm) vFmax (%) vPmax (%) Figure 8:Movement speed values obtained for the maximum moment of force in the joint (vFmax) and power (vPmax) during flexion. differences were obtained for flexion, as visualized in Figure 6. Relatively much higher values of the muscle moment and power were found depending on the speed at which the subjects achieved maximum values of these parameters. The results in this case were also higher in case of the healthy limb (Figures 7 and 8). Summary Methods for rehabilitation of the knee and their effects are widely discussed in the literature [14­16]. The results presented in this article justify the conclusion that the type of load has a major effect on the obtained results during tests of the knee joint under kinematic conditions. Inertia weights (weights and pendulum) proved to be least comfortable and safe. Hydraulic weight ensures the highest safety and comfort of the exercise, as it provides the best feeling of stability of load throughout the angular range of movement. When there is no reaction on the part of the subject, the resistance moment in the hydraulic weight fades out. For this reason, this method is specifically indicated for tests and rehabilitation exercises for persons with knee joint injuries. The presented test methods, the minimum time method for healthy persons, and the method based on comparing the results obtained for the injured and healthy lower limbs, proved their effectiveness with the improvement of the condition of the movement organ of the knee joint. Author contributions: All the authors have accepted responsibility for the entire content of the submitted manuscript and approved submission. Research funding: None declared. Employment or leadership: None declared. Honorarium: None declared. Competing interests: The funding organization(s) played no role in the study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the report for publication.

Journal

Bio-Algorithms and Med-Systemsde Gruyter

Published: Dec 1, 2015

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