Dorsey S. Williams

Gender differences in lower extremity mechanics during running.

OBJECTIVE To compare differences in hip and knee kinematics and kinetics in male and female recreational runners. DESIGN Gait analysis of 20 men and 20 women recreational runners. BACKGROUND Female runners are reported to be more likely to sustain certain lower extremity injuries compared to their male counterparts. This has been attributed, in part, to differences in their structure and it has been postulated that these structural differences may lead to differences in running mechanics. It was hypothesized that females would exhibit greater peak hip adduction, hip internal rotation, knee abduction and decreased knee internal rotation compared to their male counterparts. It was also hypothesized that females would exhibit greater hip and knee negative work in the frontal and transverse planes compared to males. METHODS Comparisons of hip and knee three-dimentional joint angles and negative work during the stance phase of running gait were made between genders. RESULTS Female recreational runners demonstrated a significantly greater peak hip adduction, hip internal rotation and knee abduction angle compared to men. Female recreational runners also demonstrated significantly greater hip frontal and transverse plane negative work compared to male recreational runners. CONCLUSION Female recreational runners exhibit significantly different lower extremity mechanics in the frontal and transverse planes at the hip and knee during running compared to male recreational runners. RELEVANCE Understanding the differences in running mechanics between male and female runners may lend insight into the etiology of different injury patterns seen between genders. In addition, these results suggest that care should be taken to account for gender when studying groups of male and female recreational runners.

Arch structure and injury patterns in runners

OBJECTIVE The purpose of this study was to determine if high-arched and low-arched runners exhibit different injury patterns. DESIGN Non-randomized, two-group injury survey. BACKGROUND Running-related injuries are thought to be related, in part, to lower extremity structure. High-arched and low-arched runners with their different bony architecture may exhibit very different lower extremity mechanics and, consequently, different injury patterns. It was hypothesized that high-arched runners will exhibit a greater incidence of lateral injuries, skeletal injuries and knee injuries while low-arched runners will show a greater incidence of medial injuries, soft tissue injuries and foot injuries. METHODS Twenty high-arched and 20 low-arched runners were included in this study. Running-related injuries were recorded and divided into injury patterns of medial/lateral, bony/soft tissue and knee/foot and ankle for both high-arched and low-arched runners. A chi(2) analysis was then employed in an attempt to associate injury patterns with arch structure. RESULTS High-arched runners reported a greater incidence of ankle injuries, bony injuries and lateral injuries. Low-arched runners exhibited more knee injuries, soft tissue injuries and medial injuries. CONCLUSIONS Based on these results, high and low arch structure is associated with different injury patterns in runners. Relevance. Different injury patterns are present in individuals with extreme high arches when compared to those with extremely low arches. These relationships may lead to improved treatment and intervention strategies for runners based on their predisposing foot structure.

High-arched runners exhibit increased leg stiffness compared to low-arched runners

Leg stiffness between high-arched (HA) and low-arched (LA) runners was compared. It was hypothesized that high-arched runners would exhibit increased leg stiffness, increased sagittal plane support moment, greater vertical loading rates, decreased knee flexion excursion and increased activation of the knee extensor musculature. Twenty high-arched and 20 low-arched subjects were included in this study. Leg stiffness, knee stiffness, vertical loading rate and lower extremity support moment were compared between groups. Electromyographic data were collected in an attempt to explain differences in leg stiffness between groups. High-arched subjects were found to have increased leg stiffness and vertical loading rate compared to low-arched runners. Support moment at the impact peak of the vertical ground reaction force was related to leg stiffness across all subjects. High-arched subjects demonstrated decreased knee flexion excursion during stance. Finally, high-arched subjects exhibited a significantly earlier onset of the vastus lateralis (VL) than the low-arched runners. Differences exist in leg stiffness and vertical loading rate between runners with different foot types. Differences in lower extremity kinetics in individuals with different foot types may have implications for new treatment strategies or preventative measures.

A comparison of within- and between-day reliability of discrete 3D lower extremity variables in runners

It is important to understand the day‐to‐day variability that is attributed to repositioning of markers especially when assessing a treatment effect or response over time. While previous studies have reported reliability of waveform patterns, none have assessed the repeatability of discrete points such as peak angles, velocities and angular excursions which are often used when making statistical and clinical comparisons. The purpose of this study was to compare the within‐ and between‐day variability of discrete kinematic, kinetic, and ground reaction force (GRF) data collected during running. Comparisons for 20 recreational runners were evaluated for within‐ and between‐day reliability of discrete 3D kinematic, kinetic, and GRF variables. The results indicated that within‐day comparisons were more reliable than between‐day. Joint angular velocity and angular excursion values were more reliable between‐days as compared to absolute peak angle measures and may be more useful in interpreting changes in treatment over time. Between‐day kinematic and kinetic sagittal plane values were more reliable than secondary plane values. Reliability of GRF data was greater than kinematic and kinetic data for between‐day comparisons.

Effect of inverted orthoses on lower-extremity mechanics in runners

INTRODUCTION Foot orthoses are recommended for individuals with injuries associated with abnormal lower-extremity mechanics. However, the biomechanical effect of these devices is not completely understood. Most clinicians and researchers believe that foot orthoses are effective in reducing some aspect of rearfoot motion. This is important as many injuries are suggested to be the result of increased pronation. Inverted orthoses are a more aggressive treatment in those whose symptoms do not respond to standard orthotics. They are likely to alter motion in all planes. However, no three-dimensional studies have assessed lower-extremity mechanics in individuals wearing inverted orthotics. PURPOSE The purpose of this study was to compare the three-dimensional kinematics and kinetics of the rearfoot and knee during running while varying orthotic intervention. METHODS Eleven subjects were initially fitted with standard foot orthoses and then with inverted orthoses. Three-dimensional kinematic and kinetic data were collected for conditions of no orthoses, standard orthoses, and inverted orthoses. RESULTS There were no differences between conditions in peak rearfoot eversion or rearfoot eversion excursion. Peak rearfoot inversion moment and work were significantly reduced (P = 0.045 and P < 0.001, respectively) in the inverted orthotic condition suggesting a decreased demand on the soft tissue structures that control eversion. Significant differences were seen in tibial rotation (P = 0.043), knee adduction (P = 0.035), and knee abduction moment (P < 0.001) in the inverted orthotic condition, suggesting alterations were made further up the kinetic chain. CONCLUSIONS The differences in kinetic parameters at the rearfoot may result in fewer injuries of the rearfoot soft tissue structures when using inverted orthotics. These alterations in lower-extremity mechanics associated with inverted orthoses provide clinicians some evidence for prescribing this device.

Sagittal and frontal plane joint mechanics throughout the stance phase of walking in adolescents who are obese.

The incidence of obesity has increased dramatically in children and adolescents, and with this comes health risks typically associated with adult obesity. Among those health consequences are musculoskeletal damage and pain. Previous studies have demonstrated inconsistent effects of increased body mass on movement patterns in adults and children who are obese. The purpose of this study was to investigate frontal and sagittal plane mechanics during walking in adolescents who were obese. Adolescents (12-17 years) who were obese were recruited from a weight management program, and healthy weight peers (matched for age, race and gender) were recruited from the community. Three-dimensional motion analysis of the lower extremities was performed during walking. Analysis of kinematic and kinetic data from 36 adolescents who were obese and healthy weight revealed significant differences in mechanics at all lower extremity joints in both sagittal and frontal planes. Subjects who were obese seemed to use movement strategies that minimized joint moments, especially at the hip and knee during walking. The lower extremity mechanics during walking in the subjects who were obese raise concerns about maintenance of structural integrity of the lower extremity joints over time, given the repeated high stresses across the joints even with walking. Neither the long term consequences of these atypical movement patterns, nor the ability to alter these patterns through therapeutic activities or weight loss has been investigated in adolescents who are obese.

A comparison of four methods of obtaining a negative impression of the foot.

Four methods are currently available for taking a negative impression of the foot for the purpose of fabricating an orthotic device: nonweightbearing plaster casting, partial-weightbearing foam impressions, and partial-weightbearing and nonweightbearing laser scanning. This study compares the reliability and accuracy of these methods. Each impression method was performed three times on each foot of 15 subjects. Measures of rearfoot and forefoot width, forefoot-to-rearfoot relationship, and arch height were obtained from the negative impressions. Additionally, rearfoot and forefoot width and forefoot-to-rearfoot relationship were measured clinically for each subject. This study found that 1) foot measures are significantly influenced by the method used to obtain a negative foot impression; 2) the methods differ in reliability; and 3) plaster casting may be preferable to the other three methods when it is important to capture the forefoot-to-rearfoot relationship, as in fabricating a functional orthosis.

Anterior cruciate ligament injury in female and male athletes: the relationship between foot structure and injury.

BACKGROUND It has been shown that anterior cruciate ligament (ACL) injuries are more prevalent in female athletes than in male athletes. Soccer and basketball are considered high-risk sports for ACL injury in female athletes. Several studies have reported a relationship between ACL injury and measures of foot structure. This study was conducted to investigate the relationship between foot structure and ACL injury rates in female and male soccer and basketball players. METHODS One hundred five soccer and basketball players (53 women and 52 men) were recruited and divided into an ACL-normal group (n=89) and an ACL-injured group (n=16). Two measures of foot structure (subtalar joint neutral position and navicular drop test values) were recorded for each subject. An independent t test and a paired t test were used to analyze differences in ACL status, foot structure, and sex. A chi2 analysis determined whether the prevalence of ACL injury was independent of sport. RESULTS No statistically significant differences were found in the foot structure measures between women and men. Female soccer and basketball players had an ACL injury rate seven times that of male players. CONCLUSIONS Values derived from subtalar joint neutral position measurement and the navicular drop test were not associated with ACL injury in collegiate female and male soccer and basketball players.