Background: Athletes, especially female athletes, experience high rates of tibial bone stress inj... more Background: Athletes, especially female athletes, experience high rates of tibial bone stress injuries (BSIs). Knowledge of tibial loads during walking and running is needed to understand injury mechanisms and design safe running progression programs. Purpose: To examine tibial loads as a function of gait speed in male and female runners. Study Design: Controlled laboratory study. Methods: Kinematic and kinetic data were collected on 40 recreational runners (20 female, 20 male) during 4 instrumented gait speed conditions on a treadmill (walk, preferred run, slow run, fast run). Musculoskeletal modeling, using participant-specific magnetic resonance imaging and motion data, was used to estimate tibial stress. Peak tibial stress and stress-time impulse were analyzed using 2-factor multivariate analyses of variance (speed*sex) and post hoc comparisons (a = .05). Bone geometry and tibial forces and moments were examined. Results: Peak compression was influenced by speed (P \ .001); increasing speed generally increased tibial compression in both sexes. Women displayed greater increases in peak tension (P = .001) and shear (P \ .001) than men when transitioning from walking to running. Further, women displayed greater peak tibial stress overall (P \ .001). Compressive and tensile stress-time impulse varied by speed (P \ .001) and sex (P = .006); impulse was lower during running than walking and greater in women. A shear stress-time impulse interaction (P \ .001) indicated that women displayed greater impulse relative to men when changing from a walk to a run. Compared with men, women displayed smaller tibiae (P \ .001) and disproportionately lower tibial forces (P .001-.035). Peak tibial stress increased with gait speed, with a 2-fold increase in running relative to walking. Women displayed greater tibial stress than men and greater increases in stress when shifting from walking to running. Sex differences appear to be the result of smaller bone geometry in women and tibial forces that were not proportionately lower, given the womens' smaller stature and lower mass relative to men. Clinical Relevance: These results may inform interventions to regulate running-related training loads and highlight a need to increase bone strength in women. Lower relative bone strength in women may contribute to a sex bias in tibial BSIs, and female runners may benefit from a slower progression when initiating a running program.
In the original publication of the article, Fig. did not include the peak knee extension moment d... more In the original publication of the article, Fig. did not include the peak knee extension moment data. The correct Fig. is given below: The online version of the original article can be found under
The purpose of this study was to quantify characteristics of bimanual movement intensity during 3... more The purpose of this study was to quantify characteristics of bimanual movement intensity during 30-hour Hand Arm Bimanual Intensive Therapy (HABIT) and bimanual performance (activities and participation) in real-world using accelerometers in children with unilateral cerebral palsy (UCP). Twenty-five children with UCP participated in a 30-hour HABIT program. Data was collected from bilateral wrist-worn accelerometers during 30-hours HABIT to quantify the movement intensity, and three days pre- and post-HABIT to assess real-world performance gains. Movement intensity and performance gains were measured using six standard accelerometer-derived variables. Bimanual capacity (body function and activities) was assessed using standardized hand function tests. We found that accelerometer variables increased significantly during HABIT, indicating increased bimanual symmetry and intensity. Post-HABIT, children demonstrated significant improvements in all accelerometer metrics, reflecting real-...
apist assistants who are beginning their doctoral studies. The Foundation wishes these students t... more apist assistants who are beginning their doctoral studies. The Foundation wishes these students the best of luck during the course of their studies.
OBJECTIVE. The goal of this prospective randomized study was to determine whether isosmolar contr... more OBJECTIVE. The goal of this prospective randomized study was to determine whether isosmolar contrast material offers an advantage over low-osmolar contrast material for delayed venous opacification in CT venography. SUBJECTS AND METHODS. We prospectively enrolled 200 adult outpatients. Patients were randomized to receive either the low-osmolar (hyperosmolar to blood) nonionic contrast medium, iohexol, or the nonionic isosmolar contrast medium, iodixanol. Images were obtained before contrast administration and 180 sec after contrast administration through the pelvis at the level of the external iliac vessels. Opacification of the external iliac vessels was assessed both objectively and subjectively. RESULTS. The arterial and venous densities before contrast administration were approximately 45 H for both groups. On delayed images obtained after contrast administration, the mean venous density was 95.2 H for iohexol and 101.4 H for iodixanol. Changes in venous density due to administration of iohexol and iodixanol were 49.8 and 56.1 H, respectively. This 12.5% difference was highly significant (p = 0.002). Sixty-six percent of the images in the iodixanol group were rated either 4 (good) or 5 (excellent), whereas only 36% of the iohexol group achieved a similar rating on our subjective rating scale. This difference was statistically significant (χ 2 = 16.4, p < 0.001, df = 1). CONCLUSION. Our study shows that isosmolar contrast material provides significant improvement in delayed opacification of the external iliac vessels in comparison with conventional low-osmolar contrast medium (hyperosmolar to blood).
Advances in Neuroergonomics and Cognitive Engineering, 2020
When walking on a treadmill, people can experience a sensory mismatch resulting from the lack of ... more When walking on a treadmill, people can experience a sensory mismatch resulting from the lack of visual flow. In this study, functional Near-Infrared Spectrometry (fNIRS) was used to investigate hemodynamic changes in the brain during overground and treadmill walking. Nine healthy right-handed subjects (25 ± 3 years) were recruited in this study. The test conditions included walking overground, on a split-belt treadmill, and on a standard treadmill. Results showed significantly increased activity in the prefrontal cortex (PFC) and the temporoparietal junction (Vestibular Cortex-VEST) on both treadmills compared with overground walking. Walking on the standard treadmill significantly increased activation in the PFC and both the left and right VEST compared with the split-belt treadmill. Our results suggest that walking on the treadmill provokes increased PFC and VEST activation. This finding may explain the fleeting sensation of dizziness after stopping walking on a treadmill.
The inherit injury risk associated with high-impact exercises calls for alternative ways to achie... more The inherit injury risk associated with high-impact exercises calls for alternative ways to achieve the benefits of aerobic exercise while minimizing excessive stresses to body tissues. Skipping presents such an alternative, incorporating double support, flight, and single support phases. We used ground reaction forces (GRFs), lower extremity joint torques and powers to compare skipping and running in 20 healthy adults. The two consecutive skipping steps on each limb differed significantly from each other, and from running. Running had the longest step length, the highest peak vertical GRF, peak knee extensor torque, and peak knee negative and positive power and negative and positive work. Skipping had the greater cadence, peak horizontal GRF, peak hip and ankle extensor torques, peak ankle negative power and work, and peak ankle positive power. The second vs first skipping step had the shorter step length, higher cadence, peak horizontal GRF, peak ankle extensor torque, and peak an...
Old compared to young adults exhibit increased hip and decreased ankle mechanical output during w... more Old compared to young adults exhibit increased hip and decreased ankle mechanical output during walking - a phenomenon known as biomechanical plasticity. Previous comparison studies suggest that low compared to high capacity old adults exhibit larger magnitudes of this plasticity, however the precise relationship between capacity and plasticity magnitude remains unclear. The purpose of this study was to quantify the relationships between physical capacity and biomechanical plasticity magnitude during level and incline walking. Data were collected for 32 old adults walking over level and inclined (+10°) surfaces at self-selected, comfortable speeds. Physical capacity was measured using the Short-Form Health Survey Physical Component (SF-36 PC) and biomechanical plasticity was quantified by ratios of hip extensor to ankle plantarfexor peak torques, angular impulses, peak positive powers, and positive work (larger ratios indicate larger magnitudes of plasticity). SF-36 PC scores correl...
Journal of oral & facial pain and headache, Jan 20, 2018
To test whether the Neck Disability Index (NDI) would indicate higher reported disability among p... more To test whether the Neck Disability Index (NDI) would indicate higher reported disability among people with neck pain, cervicogenic headache, and temporomandibular disorders (TMD) when compared to people with only neck pain or neck pain with cervicogenic headache. A total of 62 participants were enrolled and categorized into one of three groups: (1) neck pain only; (2) neck pain and cervicogenic headache; and (3) neck pain, cervicogenic headache, and TMD. NDI scores, pain, cervical active range of motion (AROM), and maximum mouth opening (MMO) were recorded for each subject. NDI scores were compared between groups using the Kruskal-Wallis test, and associations between the NDI and pain, cervical AROM, and MMO were tested using Pearson correlations. No statistical difference in NDI score was identified among the three groups (P = .08). NDI scores were not correlated with MMO (P = .17) or TMD pain (P = .16), but were correlated with cervical AROM (r = -0.635 to -0.311), cervicogenic h...
Journal of orthopaedic research : official publication of the Orthopaedic Research Society, Jan 28, 2018
Knee osteoarthritis is a major public health problem and adults with obesity are particularly at ... more Knee osteoarthritis is a major public health problem and adults with obesity are particularly at risk. One approach to alleviating this problem is to reduce the mechanical load at the joint during daily activity. Adjusting temporospatial parameters of walking could mitigate cumulative knee joint mechanical loads. The purpose of this study was to determine how adjustments to velocity and step length affects knee joint loading in healthy weight adults and adults with obesity. We collected three-dimensional gait analysis data on 10 adults with a normal body mass index and 10 adults with obesity during over ground walking in nine different conditions. In addition to preferred velocity and step length, we also conducted combinations of 15% increased and decreased velocity and step length. Peak tibiofemoral joint impulse and knee adduction angular impulse were reduced in the decreased step length conditions in both healthy weight adults (main effect) and those with obesity (interaction ef...
International Journal of Athletic Therapy and Training
Frontal plane knee alignment can influence the development and management of various knee patholo... more Frontal plane knee alignment can influence the development and management of various knee pathologies. Valid and reliable clinical methods for assessment are needed. The primary purposes of this study were to assess the validity and reliability of inclinometer-based frontal plane tibial orientation as a limb alignment measure, and secondarily to establish normal values in healthy individuals. Frontal tibial orientation was validated per moderately strong correlation to radiographic knee alignment. Intra- and interrater reliability were excellent. The normative mean was approximately 7°. In summary, inclinometer-based frontal tibial orientation is a valid and reliable clinical measure of frontal plane knee alignment.
Deficits in plantarflexor function are common after an Achilles tendon rupture. These deficits ma... more Deficits in plantarflexor function are common after an Achilles tendon rupture. These deficits may result in an altered distribution of joint loads during lower extremity tasks. We hypothesized that, regardless of treatment, the Achilles tendon-ruptured limb would exhibit deficits in ankle kinematics and joint power while exhibiting elevated knee joint power and patellofemoral joint loads during walking, jogging, and hopping. We further hypothesized that this loading pattern would be most evident during jogging and hopping. Controlled laboratory study. Thirty-four participants (17 participants treated surgically, 17 treated nonsurgically) were tested at a mean 6.1 ± 2.0 years after an Achilles tendon rupture. Lower extremity kinematics and kinetics were assessed while participants completed walking, jogging, and single-legged hopping trials. Patellofemoral joint stress was calculated via a musculoskeletal model. Data were analyzed via mixed-model repeated analyses of variance (α = ....
The purpose of this study was to examine the effects of step length and foot strike pattern along... more The purpose of this study was to examine the effects of step length and foot strike pattern along with their interaction on tibiofemoral joint (TFJ) and medial compartment TFJ kinetics during running. Nineteen participants ran with a rear foot strike pattern at their preferred speed using a short (-10%), preferred, and long (+10%) step length. These step length conditions were then repeated using a forefoot strike pattern. Regardless of foot strike pattern, a 10% shorter step length resulted in decreased peak contact force, force impulse per step, force impulse per kilometre, and average loading rate at the TFJ and medial compartment, while a 10% increased step length had the opposite effects (all P < 0.05). A forefoot strike pattern significantly lowered TFJ and medial compartment TFJ average loading rates compared with a rear foot strike pattern (both <0.05) but did not change TFJ or medial compartment peak force, force impulse per step, or force impulse per km. The combinat...
Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess... more Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess change in these forces that accompany load-modifying interventions, minimum detectable change (MDC) thresholds must be established. The primary study purpose was to derive MDCs for medial tibiofemoral peak force and force impulse during walking. The secondary purpose was to identify the proportions of individuals exhibiting reductions greater than these MDCs when walking with lateral foot wedging. Eight healthy individuals provided three-dimensional gait data over three test sessions to serve as inputs for an inverse dynamics-driven medial tibiofemoral contact force model, from which MDCs for peak force and impulse were derived. The MDC was 0.246 BW (8.7%) for peak force and 0.0385 BW*s (3.7%) for impulse. Then, 25 healthy individuals provided gait data walking with and without 6 degree laterally wedged foot orthoses and the proportion of individuals exhibiting changes in medial tibiofe...
Understanding how body-borne mass influences knee loads during running and how to modulate these ... more Understanding how body-borne mass influences knee loads during running and how to modulate these knee loads may assist efforts to reduce the high rate of knee injuries in military populations. We tested a) the extent a 15-kg body-borne load affects peak and cumulative patellofemoral (PFJ) and tibiofemoral (TFJ) contact forces during running and b) if a 7.5% increase in running cadence modulates these contact forces. Compared with unloaded running, the body-borne load increased peak PFJ contact force (+0.2 body weights; p=0.001) and PFJ impulse (+32 body weights per km; p<0.001). Additionally, greater peak total TFJ contact force (+0.5 body weights; p<0.001) and greater peak medial TFJ contact force (+0.4 body weights; p=0.002) resulted with the added load. Similarly, 85 additional body weights of total TFJ impulse per km (p<0.001) and 65 additional body weights of medial TFJ impulse per km (p<0.001) were noted with the added load. The higher cadence condition reduced pea...
The American Journal of Sports Medicine, Apr 30, 2008
Background Patellofemoral pain is especially common among female athletes and is traditionally as... more Background Patellofemoral pain is especially common among female athletes and is traditionally associated with lower extremity mechanics thought to increase retropatellar stress. These detrimental mechanics may increase with exertion. Hypothesis Differences in lower extremity mechanics during single-legged jumps between female athletes with and without patellofemoral pain will increase after exertion. Study Design Controlled laboratory study. Methods Twenty women with patellofemoral pain and 20 healthy female controls participated in a functional lower extremity exertion protocol of repetitive single-legged jumps. Pain, exertion, hip and trunk strength, and 3-dimensional lower extremity joint mechanics were recorded at the beginning and end of the protocol. Results The patellofemoral pain group reported increased pain at the conclusion of the protocol. However, all subjects terminated the protocol due to complaints of fatigue. Mean strength measurements for the patellofemoral pain group were 24% lower for lateral trunk flexion ( P = .06), 13% lower for hip abduction ( P = .09), and 14% lower for hip external rotation ( P = .03) than for controls. Subjects with patellofemoral pain demonstrated greater contralateral pelvic drop at the end of the exertion protocol compared with the control group ( P = .003). Group differences in lower extremity mechanics, including increased hip adduction angle, hip flexion angle, hip abduction angular impulse, and decreased hip internal rotation angles, were observed among women with patellofemoral pain throughout the exertion protocol. These group differences were consistent despite increased pain for the patellofemoral pain group after exertion. Both groups demonstrated decreased jump height, hip flexion and internal rotation, knee flexion, and hip extension impulse at the end of the protocol. Conclusion Women with patellofemoral pain demonstrated lower extremity mechanics that differed from the healthy control group during single-legged jumping, particularly at the hip. These differences do not appear to vary with exertion level or pain among patellofemoral pain subjects during single-legged jumps. Clinical Relevance Lower extremity jumping mechanics appear to be consistently different among women with patellofemoral pain. Conservative treatment programs that include kinematic retraining as well as hip and trunk strengthening may improve patient outcomes and prevent recurrence of this common orthopaedic condition.
Background: Athletes, especially female athletes, experience high rates of tibial bone stress inj... more Background: Athletes, especially female athletes, experience high rates of tibial bone stress injuries (BSIs). Knowledge of tibial loads during walking and running is needed to understand injury mechanisms and design safe running progression programs. Purpose: To examine tibial loads as a function of gait speed in male and female runners. Study Design: Controlled laboratory study. Methods: Kinematic and kinetic data were collected on 40 recreational runners (20 female, 20 male) during 4 instrumented gait speed conditions on a treadmill (walk, preferred run, slow run, fast run). Musculoskeletal modeling, using participant-specific magnetic resonance imaging and motion data, was used to estimate tibial stress. Peak tibial stress and stress-time impulse were analyzed using 2-factor multivariate analyses of variance (speed*sex) and post hoc comparisons (a = .05). Bone geometry and tibial forces and moments were examined. Results: Peak compression was influenced by speed (P \ .001); increasing speed generally increased tibial compression in both sexes. Women displayed greater increases in peak tension (P = .001) and shear (P \ .001) than men when transitioning from walking to running. Further, women displayed greater peak tibial stress overall (P \ .001). Compressive and tensile stress-time impulse varied by speed (P \ .001) and sex (P = .006); impulse was lower during running than walking and greater in women. A shear stress-time impulse interaction (P \ .001) indicated that women displayed greater impulse relative to men when changing from a walk to a run. Compared with men, women displayed smaller tibiae (P \ .001) and disproportionately lower tibial forces (P .001-.035). Peak tibial stress increased with gait speed, with a 2-fold increase in running relative to walking. Women displayed greater tibial stress than men and greater increases in stress when shifting from walking to running. Sex differences appear to be the result of smaller bone geometry in women and tibial forces that were not proportionately lower, given the womens' smaller stature and lower mass relative to men. Clinical Relevance: These results may inform interventions to regulate running-related training loads and highlight a need to increase bone strength in women. Lower relative bone strength in women may contribute to a sex bias in tibial BSIs, and female runners may benefit from a slower progression when initiating a running program.
In the original publication of the article, Fig. did not include the peak knee extension moment d... more In the original publication of the article, Fig. did not include the peak knee extension moment data. The correct Fig. is given below: The online version of the original article can be found under
The purpose of this study was to quantify characteristics of bimanual movement intensity during 3... more The purpose of this study was to quantify characteristics of bimanual movement intensity during 30-hour Hand Arm Bimanual Intensive Therapy (HABIT) and bimanual performance (activities and participation) in real-world using accelerometers in children with unilateral cerebral palsy (UCP). Twenty-five children with UCP participated in a 30-hour HABIT program. Data was collected from bilateral wrist-worn accelerometers during 30-hours HABIT to quantify the movement intensity, and three days pre- and post-HABIT to assess real-world performance gains. Movement intensity and performance gains were measured using six standard accelerometer-derived variables. Bimanual capacity (body function and activities) was assessed using standardized hand function tests. We found that accelerometer variables increased significantly during HABIT, indicating increased bimanual symmetry and intensity. Post-HABIT, children demonstrated significant improvements in all accelerometer metrics, reflecting real-...
apist assistants who are beginning their doctoral studies. The Foundation wishes these students t... more apist assistants who are beginning their doctoral studies. The Foundation wishes these students the best of luck during the course of their studies.
OBJECTIVE. The goal of this prospective randomized study was to determine whether isosmolar contr... more OBJECTIVE. The goal of this prospective randomized study was to determine whether isosmolar contrast material offers an advantage over low-osmolar contrast material for delayed venous opacification in CT venography. SUBJECTS AND METHODS. We prospectively enrolled 200 adult outpatients. Patients were randomized to receive either the low-osmolar (hyperosmolar to blood) nonionic contrast medium, iohexol, or the nonionic isosmolar contrast medium, iodixanol. Images were obtained before contrast administration and 180 sec after contrast administration through the pelvis at the level of the external iliac vessels. Opacification of the external iliac vessels was assessed both objectively and subjectively. RESULTS. The arterial and venous densities before contrast administration were approximately 45 H for both groups. On delayed images obtained after contrast administration, the mean venous density was 95.2 H for iohexol and 101.4 H for iodixanol. Changes in venous density due to administration of iohexol and iodixanol were 49.8 and 56.1 H, respectively. This 12.5% difference was highly significant (p = 0.002). Sixty-six percent of the images in the iodixanol group were rated either 4 (good) or 5 (excellent), whereas only 36% of the iohexol group achieved a similar rating on our subjective rating scale. This difference was statistically significant (χ 2 = 16.4, p < 0.001, df = 1). CONCLUSION. Our study shows that isosmolar contrast material provides significant improvement in delayed opacification of the external iliac vessels in comparison with conventional low-osmolar contrast medium (hyperosmolar to blood).
Advances in Neuroergonomics and Cognitive Engineering, 2020
When walking on a treadmill, people can experience a sensory mismatch resulting from the lack of ... more When walking on a treadmill, people can experience a sensory mismatch resulting from the lack of visual flow. In this study, functional Near-Infrared Spectrometry (fNIRS) was used to investigate hemodynamic changes in the brain during overground and treadmill walking. Nine healthy right-handed subjects (25 ± 3 years) were recruited in this study. The test conditions included walking overground, on a split-belt treadmill, and on a standard treadmill. Results showed significantly increased activity in the prefrontal cortex (PFC) and the temporoparietal junction (Vestibular Cortex-VEST) on both treadmills compared with overground walking. Walking on the standard treadmill significantly increased activation in the PFC and both the left and right VEST compared with the split-belt treadmill. Our results suggest that walking on the treadmill provokes increased PFC and VEST activation. This finding may explain the fleeting sensation of dizziness after stopping walking on a treadmill.
The inherit injury risk associated with high-impact exercises calls for alternative ways to achie... more The inherit injury risk associated with high-impact exercises calls for alternative ways to achieve the benefits of aerobic exercise while minimizing excessive stresses to body tissues. Skipping presents such an alternative, incorporating double support, flight, and single support phases. We used ground reaction forces (GRFs), lower extremity joint torques and powers to compare skipping and running in 20 healthy adults. The two consecutive skipping steps on each limb differed significantly from each other, and from running. Running had the longest step length, the highest peak vertical GRF, peak knee extensor torque, and peak knee negative and positive power and negative and positive work. Skipping had the greater cadence, peak horizontal GRF, peak hip and ankle extensor torques, peak ankle negative power and work, and peak ankle positive power. The second vs first skipping step had the shorter step length, higher cadence, peak horizontal GRF, peak ankle extensor torque, and peak an...
Old compared to young adults exhibit increased hip and decreased ankle mechanical output during w... more Old compared to young adults exhibit increased hip and decreased ankle mechanical output during walking - a phenomenon known as biomechanical plasticity. Previous comparison studies suggest that low compared to high capacity old adults exhibit larger magnitudes of this plasticity, however the precise relationship between capacity and plasticity magnitude remains unclear. The purpose of this study was to quantify the relationships between physical capacity and biomechanical plasticity magnitude during level and incline walking. Data were collected for 32 old adults walking over level and inclined (+10°) surfaces at self-selected, comfortable speeds. Physical capacity was measured using the Short-Form Health Survey Physical Component (SF-36 PC) and biomechanical plasticity was quantified by ratios of hip extensor to ankle plantarfexor peak torques, angular impulses, peak positive powers, and positive work (larger ratios indicate larger magnitudes of plasticity). SF-36 PC scores correl...
Journal of oral & facial pain and headache, Jan 20, 2018
To test whether the Neck Disability Index (NDI) would indicate higher reported disability among p... more To test whether the Neck Disability Index (NDI) would indicate higher reported disability among people with neck pain, cervicogenic headache, and temporomandibular disorders (TMD) when compared to people with only neck pain or neck pain with cervicogenic headache. A total of 62 participants were enrolled and categorized into one of three groups: (1) neck pain only; (2) neck pain and cervicogenic headache; and (3) neck pain, cervicogenic headache, and TMD. NDI scores, pain, cervical active range of motion (AROM), and maximum mouth opening (MMO) were recorded for each subject. NDI scores were compared between groups using the Kruskal-Wallis test, and associations between the NDI and pain, cervical AROM, and MMO were tested using Pearson correlations. No statistical difference in NDI score was identified among the three groups (P = .08). NDI scores were not correlated with MMO (P = .17) or TMD pain (P = .16), but were correlated with cervical AROM (r = -0.635 to -0.311), cervicogenic h...
Journal of orthopaedic research : official publication of the Orthopaedic Research Society, Jan 28, 2018
Knee osteoarthritis is a major public health problem and adults with obesity are particularly at ... more Knee osteoarthritis is a major public health problem and adults with obesity are particularly at risk. One approach to alleviating this problem is to reduce the mechanical load at the joint during daily activity. Adjusting temporospatial parameters of walking could mitigate cumulative knee joint mechanical loads. The purpose of this study was to determine how adjustments to velocity and step length affects knee joint loading in healthy weight adults and adults with obesity. We collected three-dimensional gait analysis data on 10 adults with a normal body mass index and 10 adults with obesity during over ground walking in nine different conditions. In addition to preferred velocity and step length, we also conducted combinations of 15% increased and decreased velocity and step length. Peak tibiofemoral joint impulse and knee adduction angular impulse were reduced in the decreased step length conditions in both healthy weight adults (main effect) and those with obesity (interaction ef...
International Journal of Athletic Therapy and Training
Frontal plane knee alignment can influence the development and management of various knee patholo... more Frontal plane knee alignment can influence the development and management of various knee pathologies. Valid and reliable clinical methods for assessment are needed. The primary purposes of this study were to assess the validity and reliability of inclinometer-based frontal plane tibial orientation as a limb alignment measure, and secondarily to establish normal values in healthy individuals. Frontal tibial orientation was validated per moderately strong correlation to radiographic knee alignment. Intra- and interrater reliability were excellent. The normative mean was approximately 7°. In summary, inclinometer-based frontal tibial orientation is a valid and reliable clinical measure of frontal plane knee alignment.
Deficits in plantarflexor function are common after an Achilles tendon rupture. These deficits ma... more Deficits in plantarflexor function are common after an Achilles tendon rupture. These deficits may result in an altered distribution of joint loads during lower extremity tasks. We hypothesized that, regardless of treatment, the Achilles tendon-ruptured limb would exhibit deficits in ankle kinematics and joint power while exhibiting elevated knee joint power and patellofemoral joint loads during walking, jogging, and hopping. We further hypothesized that this loading pattern would be most evident during jogging and hopping. Controlled laboratory study. Thirty-four participants (17 participants treated surgically, 17 treated nonsurgically) were tested at a mean 6.1 ± 2.0 years after an Achilles tendon rupture. Lower extremity kinematics and kinetics were assessed while participants completed walking, jogging, and single-legged hopping trials. Patellofemoral joint stress was calculated via a musculoskeletal model. Data were analyzed via mixed-model repeated analyses of variance (α = ....
The purpose of this study was to examine the effects of step length and foot strike pattern along... more The purpose of this study was to examine the effects of step length and foot strike pattern along with their interaction on tibiofemoral joint (TFJ) and medial compartment TFJ kinetics during running. Nineteen participants ran with a rear foot strike pattern at their preferred speed using a short (-10%), preferred, and long (+10%) step length. These step length conditions were then repeated using a forefoot strike pattern. Regardless of foot strike pattern, a 10% shorter step length resulted in decreased peak contact force, force impulse per step, force impulse per kilometre, and average loading rate at the TFJ and medial compartment, while a 10% increased step length had the opposite effects (all P < 0.05). A forefoot strike pattern significantly lowered TFJ and medial compartment TFJ average loading rates compared with a rear foot strike pattern (both <0.05) but did not change TFJ or medial compartment peak force, force impulse per step, or force impulse per km. The combinat...
Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess... more Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess change in these forces that accompany load-modifying interventions, minimum detectable change (MDC) thresholds must be established. The primary study purpose was to derive MDCs for medial tibiofemoral peak force and force impulse during walking. The secondary purpose was to identify the proportions of individuals exhibiting reductions greater than these MDCs when walking with lateral foot wedging. Eight healthy individuals provided three-dimensional gait data over three test sessions to serve as inputs for an inverse dynamics-driven medial tibiofemoral contact force model, from which MDCs for peak force and impulse were derived. The MDC was 0.246 BW (8.7%) for peak force and 0.0385 BW*s (3.7%) for impulse. Then, 25 healthy individuals provided gait data walking with and without 6 degree laterally wedged foot orthoses and the proportion of individuals exhibiting changes in medial tibiofe...
Understanding how body-borne mass influences knee loads during running and how to modulate these ... more Understanding how body-borne mass influences knee loads during running and how to modulate these knee loads may assist efforts to reduce the high rate of knee injuries in military populations. We tested a) the extent a 15-kg body-borne load affects peak and cumulative patellofemoral (PFJ) and tibiofemoral (TFJ) contact forces during running and b) if a 7.5% increase in running cadence modulates these contact forces. Compared with unloaded running, the body-borne load increased peak PFJ contact force (+0.2 body weights; p=0.001) and PFJ impulse (+32 body weights per km; p<0.001). Additionally, greater peak total TFJ contact force (+0.5 body weights; p<0.001) and greater peak medial TFJ contact force (+0.4 body weights; p=0.002) resulted with the added load. Similarly, 85 additional body weights of total TFJ impulse per km (p<0.001) and 65 additional body weights of medial TFJ impulse per km (p<0.001) were noted with the added load. The higher cadence condition reduced pea...
The American Journal of Sports Medicine, Apr 30, 2008
Background Patellofemoral pain is especially common among female athletes and is traditionally as... more Background Patellofemoral pain is especially common among female athletes and is traditionally associated with lower extremity mechanics thought to increase retropatellar stress. These detrimental mechanics may increase with exertion. Hypothesis Differences in lower extremity mechanics during single-legged jumps between female athletes with and without patellofemoral pain will increase after exertion. Study Design Controlled laboratory study. Methods Twenty women with patellofemoral pain and 20 healthy female controls participated in a functional lower extremity exertion protocol of repetitive single-legged jumps. Pain, exertion, hip and trunk strength, and 3-dimensional lower extremity joint mechanics were recorded at the beginning and end of the protocol. Results The patellofemoral pain group reported increased pain at the conclusion of the protocol. However, all subjects terminated the protocol due to complaints of fatigue. Mean strength measurements for the patellofemoral pain group were 24% lower for lateral trunk flexion ( P = .06), 13% lower for hip abduction ( P = .09), and 14% lower for hip external rotation ( P = .03) than for controls. Subjects with patellofemoral pain demonstrated greater contralateral pelvic drop at the end of the exertion protocol compared with the control group ( P = .003). Group differences in lower extremity mechanics, including increased hip adduction angle, hip flexion angle, hip abduction angular impulse, and decreased hip internal rotation angles, were observed among women with patellofemoral pain throughout the exertion protocol. These group differences were consistent despite increased pain for the patellofemoral pain group after exertion. Both groups demonstrated decreased jump height, hip flexion and internal rotation, knee flexion, and hip extension impulse at the end of the protocol. Conclusion Women with patellofemoral pain demonstrated lower extremity mechanics that differed from the healthy control group during single-legged jumping, particularly at the hip. These differences do not appear to vary with exertion level or pain among patellofemoral pain subjects during single-legged jumps. Clinical Relevance Lower extremity jumping mechanics appear to be consistently different among women with patellofemoral pain. Conservative treatment programs that include kinematic retraining as well as hip and trunk strengthening may improve patient outcomes and prevent recurrence of this common orthopaedic condition.
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