To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the di... more To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the differentiation of osteoarthritis (OA) knee joints from non-OA joints by detecting mobile protein and peptide levels in synovial fluid by determining their relative distribution. A total of 25 knees in 11 men and 12 women with knee injuries were imaged using whole knee joint proteinCEST MRI sequence at 3 T. The joint synovial fluid was segmented and the asymmetric magnetization transfer ratio at 3.5 ppm MTR(asym) (3.5 ppm) was calculated to assess protein content in the synovial fluid. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) distribution profile was compared using the independent Student's t test. The diagnostic performance of the 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in differentiating OA and non-OA knee joints was evaluated. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in knee joints with OA was 8.6%±3.4% and significantly higher than th...
ABSTRACT Background/Purpose: Obese children have a higher prevalence of lower extremity (LE) pain... more ABSTRACT Background/Purpose: Obese children have a higher prevalence of lower extremity (LE) pain, with associated diminished quality of life, greater knee malalignment, generate less knee extensor force, and are less physically active compared to healthy weight (HW) children, putting them at risk to be obese adults. In adults, obesity is one major risk factor in developing osteoarthritis (OA) that negatively affects quality of life. Obese children may have “adult” risk factors, which may confer a risk of developing OA. We explored the relationships between knee alignment, LE strength and quality of life in obese adolescents. We compared 1) knee alignment and lower extremity strength in OB and HW adolescents and 2) evaluated the relationship of BMI and LE strength, and LE strength and QOL. Methods: Adolescents (ages 11–18) recruited from pediatric community and tertiary centers were enrolled into two age and sex matched groups based on obesity status. Body mass index (BMI= kg/m2) was calculated to determine BMI Z-scores from CDC US 2002 data. QOL was assessed using the Pediatric Quality of Life™(PedsQL) physical function score. Frontal plane knee alignment was measured using umbilicus, knee and ankle landmarks. LE strength was measured bothisokinetically: quadricep peak torque (QPT) and hamstring peak torque (HSPT) and isometrically: hip abductor peak torque (AbdPT) and hip extensor peak torque (ExtPT). Peak torque was normalized to body weight and right side data were analyzed as all subjects were right leg dominant. Means and standard deviations described the data. Paired t-tests and Pearson's correlations coefficients evaluated group differences and associations among variables of interest. Results: 12 males and 10 females were enrolled. They were divided into 2 groups: OB and HW based on mean BMI and BMI z-scores are reported in Table 1. Mean PedsQL physical function scores differ by group. (Table 1). Mean right knee alignment did not differ between the OB and HW adolescents. (Table 1) The OB group had significantly lower QPT, HSPT, AbdPT, and ExtPT (Table 1). BMI Z-scores were negatively correlated with LE strength (QPT r= −0.443, p<0.05, HSPT r= −0.527, p< 0.05, AbdPT r= −0.394, p> 0.05, ExtPT r= −0.513, p< 0.05). LE strength measures were positively correlated with physical function scores (QPT r= 0.551, p< 0.05, HSPT r= 0.692, p< 0.001, AbdPT r= 0.538, p< 0.05, ExtPT r= 0.555, p< 0.05). Conclusion: OB adolescents have diminished LE strength compared to HW counterparts. Higher BMI Z-scores correlated with lower LE strength while lower LE strength correlated with reduced physical function. LE strength may limit appropriate physical activity participation in obese adolescents further contributing to obesity and other risk factors that may lead to the development of knee OA. Future research need to explore why the muscles in obese children are not responding as expected to excess load by increasing muscular strength.
Stair climbing is a common daily activity, yet there is no basic knowledge on how lower extremity... more Stair climbing is a common daily activity, yet there is no basic knowledge on how lower extremity joint angles, moments or muscle activations are affected by stair climbing speed. This information will determine whether speed matching is necessary for stair climbing studies. Moreover, changes in lower extremity biomechanics during stair climbing at different speeds will aid in the clinical interpretation of a patient's maximal stair climbing speed. Thirty healthy participants provided consent. Kinematics, kinetics, and muscle activations were collected on a three step staircase. Subjects climbed the staircase at normal, slow and fast self-selected speeds. Linear mixed models for repeated measures were used to study the associations between speed and the lower extremity peak joint angles and moments, and muscle activations. The peak hip flexion and extension moments increased with increasing speed, while peak knee flexion moment did not vary consistently with speed. The peak muscle activations varied consistently with respect to the sagittal plane kinetics. These results suggest that in healthy subjects, the hip is the greatest contributor when modulating stair climbing speed, while additional knee contributions do not appear necessary to increase speed. Further stair studies should consider speed matching in order to accurately assess biomechanical differences.
The purpose of this study was to quantify the effects of two independent treatments, soft tissue ... more The purpose of this study was to quantify the effects of two independent treatments, soft tissue mobilization and a localized heat pack, upon iliotibial band syndrome injured runner. Iliotibial band injured runners (n=5) who were actively seeking soft tissue mobilization as a treatment were recruited. These runners received one of three randomized treatments during three consecutive visits - (1) soft
The purpose of this study was to prospectively analyze a large group of marathon runners (n=20) a... more The purpose of this study was to prospectively analyze a large group of marathon runners (n=20) and test for biomechanical determinants of running injuries. The opportunity to prospectively follow runners of organized marathon training teams allowed for testing of the hypothesis that functional biomechanics may lead to iliotibial band syndrome (ITBS). Each runner was gait tested prior to developing any
Anthropometric parameters are fundamental for a wide variety of applications in biomechanics, ant... more Anthropometric parameters are fundamental for a wide variety of applications in biomechanics, anthropology, medicine and sports. Recent technological advancements provide methods for constructing 3D surfaces directly. Of these new technologies, visual hull construction may be the most cost-effective yet sufficiently accurate method. However, the conditions influencing the accuracy of anthropometric measurements based on visual hull reconstruction are unknown. The purpose of this study was to evaluate the conditions that influence the accuracy of 3D shape-from-silhouette reconstruction of body segments dependent on number of cameras, camera resolution and object contours. The results demonstrate that the visual hulls lacked accuracy in concave regions and narrow spaces, but setups with a high number of cameras reconstructed a human form with an average accuracy of 1.0 mm. In general, setups with less than 8 cameras yielded largely inaccurate visual hull constructions, while setups with 16 and more cameras provided good volume estimations. Body segment volumes were obtained with an average error of 10% at a 640x480 resolution using 8 cameras. Changes in resolution did not significantly affect the average error. However, substantial decreases in error were observed with increasing number of cameras (33.3% using 4 cameras; 10.5% using 8 cameras; 4.1% using 16 cameras; 1.2% using 64 cameras).
The aim of the study was to estimate the tibiofemoral joint force in deep flexion to consider how... more The aim of the study was to estimate the tibiofemoral joint force in deep flexion to consider how the mechanical load affects the knee. We hypothesize that the joint force should not become sufficiently large to damage the joint under normal contact area, but should become deleterious to the joint under the limited contact area. Sixteen healthy knees were analyzed using a motion capture system, a force plate, a surface electromyography, and a knee model, and then tibiofemoral joint contact forces were calculated. Also, a contact stress simulation using the contact areas from the literature was performed. The peak joint contact forces (M +/- SD) were 4566 +/- 1932 N at 140 degrees in rising from full squat and 4479 +/- 1478 N at 90 degrees in rising from kneeling. Under normal contact area, the tibiofemoral contact stresses in deep flexion were less than 5 MPa and did not exceed the stress to damage the cartilage. The contact stress simulation suggests that knee prosthesis having the...
The most common methods for accurate capture of three-dimensional human motion require a laborato... more The most common methods for accurate capture of three-dimensional human motion require a laboratory environment and the attachment of markers or fixtures to the body segments. These laboratory conditions can cause unknown experimental artifacts. Thus our understanding of normal and pathological human movement would be enhanced by a method that allows capture of human movement without the constraint of markers
Few objective data are available regarding strength and movement patterns in individuals with art... more Few objective data are available regarding strength and movement patterns in individuals with articular cartilage defects (ACDs) of the knee. To test the following hypotheses: (1) The involved limb of individuals with ACDs would demonstrate lower peak knee-flexion angle, peak internal knee-extension moment, and peak vertical ground-reaction force (vGRF) than the contralateral limb and healthy controls. (2) On the involved limb of individuals with ACDs, quadriceps femoris strength would positively correlate with peak knee-flexion angle, peak internal knee-extension moment, and peak vGRF. Cross-sectional. Biomechanics research laboratory. 11 individuals with ACDs in the knee who were eligible for surgical cartilage restoration and 10 healthy controls. Quadriceps femoris strength was quantified as peak isometric knee-extension torque via an isokinetic dynamometer. Sagittal-plane knee kinematics and kinetics were measured during the stance phase of stair ascent with 3-dimensional motion analysis. Quadriceps strength and knee biomechanics during stair ascent were compared between the involved and contralateral limbs of participants with ACD (paired t tests) and with a control group (independent-samples t tests). Pearson correlations evaluated relationships between strength and stair-ascent biomechanics. Lower quadriceps strength and peak internal knee-extension moments were observed in the involved limb than in the contralateral limb (P < .01) and the control group (P < .01). For the involved limb of the ACD group, quadriceps femoris strength was strongly correlated (r = .847) with involved-limb peak internal knee-extension moment and inversely correlated (r = -.635) with contralateral peak vGRF. Individuals with ACDs demonstrated deficits in quadriceps femoris strength with associated alterations in movement patterns during stair ascent. The results of this study are not comprehensive; further research is needed to understand the physiological characteristics, activity performance, and movement quality in this population.
To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the di... more To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the differentiation of osteoarthritis (OA) knee joints from non-OA joints by detecting mobile protein and peptide levels in synovial fluid by determining their relative distribution. A total of 25 knees in 11 men and 12 women with knee injuries were imaged using whole knee joint proteinCEST MRI sequence at 3 T. The joint synovial fluid was segmented and the asymmetric magnetization transfer ratio at 3.5 ppm MTR(asym) (3.5 ppm) was calculated to assess protein content in the synovial fluid. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) distribution profile was compared using the independent Student's t test. The diagnostic performance of the 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in differentiating OA and non-OA knee joints was evaluated. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in knee joints with OA was 8.6%±3.4% and significantly higher than th...
The purpose of this study was to determine the presence and prevalence of asymmetry in lower extr... more The purpose of this study was to determine the presence and prevalence of asymmetry in lower extremity joint moments within and across healthy populations during overground walking. Bilateral gait data from several studies performed at two institutions were pooled from 182 healthy, pain-free subjects. Four distinct populations were identified based on age, activity level and body mass index. Mean peak external joint moments were calculated from three to six trials of level overground walking at self-selected speed for each subject. Right and left limb moments were reclassified as "greater" or "lesser" moment for each subject to prevent obscuring absolute asymmetry due to averaging over positive and negative asymmetries across subjects. A clinically relevant asymmetry measure was calculated from the peak joint moments with an initial chosen cutoff value of 10%. Confidence intervals for the proportion of subjects with greater than 10% asymmetry between limbs were estimated based on the binomial distribution. We found a high amount of asymmetry between the limbs in healthy populations. More than half of our overall population exceeded 10% asymmetry in peak hip and knee flexion and adduction moments. Group medians exceeded 10% asymmetry for all variables in all populations. This may have important implications on gait evaluations, particularly clinical evaluations or research studies where asymmetry is used as an outcome. Additional research is necessary to determine acceptable levels of joint moment asymmetry during gait and to determine whether asymmetrical joint moments influence the development of symptomatic pathology or success of lower extremity rehabilitation.
ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of... more ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of a Trunk Stabilization Program on Trunk Control and Knee Loading." for more detailed information.
ABSTRACT Please see our journal article "Knee Joint Kinetics in Relation to Commonly Pre... more ABSTRACT Please see our journal article "Knee Joint Kinetics in Relation to Commonly Prescribed Squat Loads and Depths." for more detailed information.
ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of... more ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of a Trunk Stabilization Program on Trunk Control and Knee Loading." for more detailed information.
This review examines a mechanism for the initiation of osteoarthritis after anterior cruciate lig... more This review examines a mechanism for the initiation of osteoarthritis after anterior cruciate ligament (ACL) injury by considering the relationship between reported ambulatory changes after ACL injury, cartilage adaptation to load, and the association between cartilage loads during walking and regional variations in cartilage structure and biology. Taken together, these observations suggest that cartilage degeneration after ACL injury could be caused by a kinematic gait change that shifts ambulatory loading applied to cartilage. Such a shift may cause regions of cartilage to become newly loaded, be subjected to altered levels of compression and tension, or become unloaded. The metabolic sensitivity of chondrocytes to such changes in their mechanical environment, combined with the low adaptation potential of mature cartilage, could lead to cartilage degeneration and premature osteoarthritis after ACL injury. This proposed mechanism demonstrates the value of using the ACL injury model to understand the relationship between mechanics and biology, as well as helping to explain the importance of restoring normal ambulatory kinematics after ACL injury to avoid premature osteoarthritis.
To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the di... more To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the differentiation of osteoarthritis (OA) knee joints from non-OA joints by detecting mobile protein and peptide levels in synovial fluid by determining their relative distribution. A total of 25 knees in 11 men and 12 women with knee injuries were imaged using whole knee joint proteinCEST MRI sequence at 3 T. The joint synovial fluid was segmented and the asymmetric magnetization transfer ratio at 3.5 ppm MTR(asym) (3.5 ppm) was calculated to assess protein content in the synovial fluid. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) distribution profile was compared using the independent Student's t test. The diagnostic performance of the 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in differentiating OA and non-OA knee joints was evaluated. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in knee joints with OA was 8.6%±3.4% and significantly higher than th...
ABSTRACT Background/Purpose: Obese children have a higher prevalence of lower extremity (LE) pain... more ABSTRACT Background/Purpose: Obese children have a higher prevalence of lower extremity (LE) pain, with associated diminished quality of life, greater knee malalignment, generate less knee extensor force, and are less physically active compared to healthy weight (HW) children, putting them at risk to be obese adults. In adults, obesity is one major risk factor in developing osteoarthritis (OA) that negatively affects quality of life. Obese children may have “adult” risk factors, which may confer a risk of developing OA. We explored the relationships between knee alignment, LE strength and quality of life in obese adolescents. We compared 1) knee alignment and lower extremity strength in OB and HW adolescents and 2) evaluated the relationship of BMI and LE strength, and LE strength and QOL. Methods: Adolescents (ages 11–18) recruited from pediatric community and tertiary centers were enrolled into two age and sex matched groups based on obesity status. Body mass index (BMI= kg/m2) was calculated to determine BMI Z-scores from CDC US 2002 data. QOL was assessed using the Pediatric Quality of Life™(PedsQL) physical function score. Frontal plane knee alignment was measured using umbilicus, knee and ankle landmarks. LE strength was measured bothisokinetically: quadricep peak torque (QPT) and hamstring peak torque (HSPT) and isometrically: hip abductor peak torque (AbdPT) and hip extensor peak torque (ExtPT). Peak torque was normalized to body weight and right side data were analyzed as all subjects were right leg dominant. Means and standard deviations described the data. Paired t-tests and Pearson's correlations coefficients evaluated group differences and associations among variables of interest. Results: 12 males and 10 females were enrolled. They were divided into 2 groups: OB and HW based on mean BMI and BMI z-scores are reported in Table 1. Mean PedsQL physical function scores differ by group. (Table 1). Mean right knee alignment did not differ between the OB and HW adolescents. (Table 1) The OB group had significantly lower QPT, HSPT, AbdPT, and ExtPT (Table 1). BMI Z-scores were negatively correlated with LE strength (QPT r= −0.443, p<0.05, HSPT r= −0.527, p< 0.05, AbdPT r= −0.394, p> 0.05, ExtPT r= −0.513, p< 0.05). LE strength measures were positively correlated with physical function scores (QPT r= 0.551, p< 0.05, HSPT r= 0.692, p< 0.001, AbdPT r= 0.538, p< 0.05, ExtPT r= 0.555, p< 0.05). Conclusion: OB adolescents have diminished LE strength compared to HW counterparts. Higher BMI Z-scores correlated with lower LE strength while lower LE strength correlated with reduced physical function. LE strength may limit appropriate physical activity participation in obese adolescents further contributing to obesity and other risk factors that may lead to the development of knee OA. Future research need to explore why the muscles in obese children are not responding as expected to excess load by increasing muscular strength.
Stair climbing is a common daily activity, yet there is no basic knowledge on how lower extremity... more Stair climbing is a common daily activity, yet there is no basic knowledge on how lower extremity joint angles, moments or muscle activations are affected by stair climbing speed. This information will determine whether speed matching is necessary for stair climbing studies. Moreover, changes in lower extremity biomechanics during stair climbing at different speeds will aid in the clinical interpretation of a patient's maximal stair climbing speed. Thirty healthy participants provided consent. Kinematics, kinetics, and muscle activations were collected on a three step staircase. Subjects climbed the staircase at normal, slow and fast self-selected speeds. Linear mixed models for repeated measures were used to study the associations between speed and the lower extremity peak joint angles and moments, and muscle activations. The peak hip flexion and extension moments increased with increasing speed, while peak knee flexion moment did not vary consistently with speed. The peak muscle activations varied consistently with respect to the sagittal plane kinetics. These results suggest that in healthy subjects, the hip is the greatest contributor when modulating stair climbing speed, while additional knee contributions do not appear necessary to increase speed. Further stair studies should consider speed matching in order to accurately assess biomechanical differences.
The purpose of this study was to quantify the effects of two independent treatments, soft tissue ... more The purpose of this study was to quantify the effects of two independent treatments, soft tissue mobilization and a localized heat pack, upon iliotibial band syndrome injured runner. Iliotibial band injured runners (n=5) who were actively seeking soft tissue mobilization as a treatment were recruited. These runners received one of three randomized treatments during three consecutive visits - (1) soft
The purpose of this study was to prospectively analyze a large group of marathon runners (n=20) a... more The purpose of this study was to prospectively analyze a large group of marathon runners (n=20) and test for biomechanical determinants of running injuries. The opportunity to prospectively follow runners of organized marathon training teams allowed for testing of the hypothesis that functional biomechanics may lead to iliotibial band syndrome (ITBS). Each runner was gait tested prior to developing any
Anthropometric parameters are fundamental for a wide variety of applications in biomechanics, ant... more Anthropometric parameters are fundamental for a wide variety of applications in biomechanics, anthropology, medicine and sports. Recent technological advancements provide methods for constructing 3D surfaces directly. Of these new technologies, visual hull construction may be the most cost-effective yet sufficiently accurate method. However, the conditions influencing the accuracy of anthropometric measurements based on visual hull reconstruction are unknown. The purpose of this study was to evaluate the conditions that influence the accuracy of 3D shape-from-silhouette reconstruction of body segments dependent on number of cameras, camera resolution and object contours. The results demonstrate that the visual hulls lacked accuracy in concave regions and narrow spaces, but setups with a high number of cameras reconstructed a human form with an average accuracy of 1.0 mm. In general, setups with less than 8 cameras yielded largely inaccurate visual hull constructions, while setups with 16 and more cameras provided good volume estimations. Body segment volumes were obtained with an average error of 10% at a 640x480 resolution using 8 cameras. Changes in resolution did not significantly affect the average error. However, substantial decreases in error were observed with increasing number of cameras (33.3% using 4 cameras; 10.5% using 8 cameras; 4.1% using 16 cameras; 1.2% using 64 cameras).
The aim of the study was to estimate the tibiofemoral joint force in deep flexion to consider how... more The aim of the study was to estimate the tibiofemoral joint force in deep flexion to consider how the mechanical load affects the knee. We hypothesize that the joint force should not become sufficiently large to damage the joint under normal contact area, but should become deleterious to the joint under the limited contact area. Sixteen healthy knees were analyzed using a motion capture system, a force plate, a surface electromyography, and a knee model, and then tibiofemoral joint contact forces were calculated. Also, a contact stress simulation using the contact areas from the literature was performed. The peak joint contact forces (M +/- SD) were 4566 +/- 1932 N at 140 degrees in rising from full squat and 4479 +/- 1478 N at 90 degrees in rising from kneeling. Under normal contact area, the tibiofemoral contact stresses in deep flexion were less than 5 MPa and did not exceed the stress to damage the cartilage. The contact stress simulation suggests that knee prosthesis having the...
The most common methods for accurate capture of three-dimensional human motion require a laborato... more The most common methods for accurate capture of three-dimensional human motion require a laboratory environment and the attachment of markers or fixtures to the body segments. These laboratory conditions can cause unknown experimental artifacts. Thus our understanding of normal and pathological human movement would be enhanced by a method that allows capture of human movement without the constraint of markers
Few objective data are available regarding strength and movement patterns in individuals with art... more Few objective data are available regarding strength and movement patterns in individuals with articular cartilage defects (ACDs) of the knee. To test the following hypotheses: (1) The involved limb of individuals with ACDs would demonstrate lower peak knee-flexion angle, peak internal knee-extension moment, and peak vertical ground-reaction force (vGRF) than the contralateral limb and healthy controls. (2) On the involved limb of individuals with ACDs, quadriceps femoris strength would positively correlate with peak knee-flexion angle, peak internal knee-extension moment, and peak vGRF. Cross-sectional. Biomechanics research laboratory. 11 individuals with ACDs in the knee who were eligible for surgical cartilage restoration and 10 healthy controls. Quadriceps femoris strength was quantified as peak isometric knee-extension torque via an isokinetic dynamometer. Sagittal-plane knee kinematics and kinetics were measured during the stance phase of stair ascent with 3-dimensional motion analysis. Quadriceps strength and knee biomechanics during stair ascent were compared between the involved and contralateral limbs of participants with ACD (paired t tests) and with a control group (independent-samples t tests). Pearson correlations evaluated relationships between strength and stair-ascent biomechanics. Lower quadriceps strength and peak internal knee-extension moments were observed in the involved limb than in the contralateral limb (P < .01) and the control group (P < .01). For the involved limb of the ACD group, quadriceps femoris strength was strongly correlated (r = .847) with involved-limb peak internal knee-extension moment and inversely correlated (r = -.635) with contralateral peak vGRF. Individuals with ACDs demonstrated deficits in quadriceps femoris strength with associated alterations in movement patterns during stair ascent. The results of this study are not comprehensive; further research is needed to understand the physiological characteristics, activity performance, and movement quality in this population.
To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the di... more To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the differentiation of osteoarthritis (OA) knee joints from non-OA joints by detecting mobile protein and peptide levels in synovial fluid by determining their relative distribution. A total of 25 knees in 11 men and 12 women with knee injuries were imaged using whole knee joint proteinCEST MRI sequence at 3 T. The joint synovial fluid was segmented and the asymmetric magnetization transfer ratio at 3.5 ppm MTR(asym) (3.5 ppm) was calculated to assess protein content in the synovial fluid. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) distribution profile was compared using the independent Student's t test. The diagnostic performance of the 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in differentiating OA and non-OA knee joints was evaluated. The 85th percentile of synovial fluid MTR(asym) (3.5 ppm) in knee joints with OA was 8.6%±3.4% and significantly higher than th...
The purpose of this study was to determine the presence and prevalence of asymmetry in lower extr... more The purpose of this study was to determine the presence and prevalence of asymmetry in lower extremity joint moments within and across healthy populations during overground walking. Bilateral gait data from several studies performed at two institutions were pooled from 182 healthy, pain-free subjects. Four distinct populations were identified based on age, activity level and body mass index. Mean peak external joint moments were calculated from three to six trials of level overground walking at self-selected speed for each subject. Right and left limb moments were reclassified as "greater" or "lesser" moment for each subject to prevent obscuring absolute asymmetry due to averaging over positive and negative asymmetries across subjects. A clinically relevant asymmetry measure was calculated from the peak joint moments with an initial chosen cutoff value of 10%. Confidence intervals for the proportion of subjects with greater than 10% asymmetry between limbs were estimated based on the binomial distribution. We found a high amount of asymmetry between the limbs in healthy populations. More than half of our overall population exceeded 10% asymmetry in peak hip and knee flexion and adduction moments. Group medians exceeded 10% asymmetry for all variables in all populations. This may have important implications on gait evaluations, particularly clinical evaluations or research studies where asymmetry is used as an outcome. Additional research is necessary to determine acceptable levels of joint moment asymmetry during gait and to determine whether asymmetrical joint moments influence the development of symptomatic pathology or success of lower extremity rehabilitation.
ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of... more ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of a Trunk Stabilization Program on Trunk Control and Knee Loading." for more detailed information.
ABSTRACT Please see our journal article "Knee Joint Kinetics in Relation to Commonly Pre... more ABSTRACT Please see our journal article "Knee Joint Kinetics in Relation to Commonly Prescribed Squat Loads and Depths." for more detailed information.
ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of... more ABSTRACT Please see our 2012 MSSE article "Randomized Controlled Trial of the Effects of a Trunk Stabilization Program on Trunk Control and Knee Loading." for more detailed information.
This review examines a mechanism for the initiation of osteoarthritis after anterior cruciate lig... more This review examines a mechanism for the initiation of osteoarthritis after anterior cruciate ligament (ACL) injury by considering the relationship between reported ambulatory changes after ACL injury, cartilage adaptation to load, and the association between cartilage loads during walking and regional variations in cartilage structure and biology. Taken together, these observations suggest that cartilage degeneration after ACL injury could be caused by a kinematic gait change that shifts ambulatory loading applied to cartilage. Such a shift may cause regions of cartilage to become newly loaded, be subjected to altered levels of compression and tension, or become unloaded. The metabolic sensitivity of chondrocytes to such changes in their mechanical environment, combined with the low adaptation potential of mature cartilage, could lead to cartilage degeneration and premature osteoarthritis after ACL injury. This proposed mechanism demonstrates the value of using the ACL injury model to understand the relationship between mechanics and biology, as well as helping to explain the importance of restoring normal ambulatory kinematics after ACL injury to avoid premature osteoarthritis.
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