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Biomedical subjects

Irene S Davis

Publications and source records attributed to Irene S Davis.

7 recordsLinked to original sources
PubMed2006

Biomechanical factors associated with tibial stress fracture in female runners.

PURPOSE: Tibial stress fractures (TSF) are among the most serious running injuries, typically requiring 6-8 wk for recovery. This cross-sectional study was conducted to determine whether differences in structure and running mechanics exist between trained distance runners with a history of prior TSF and those who have never sustained a fracture. METHODS: Female runners with a rearfoot strike pattern, aged between 18 and 45 yr and running at least 32 km.wk(-1), were recruited for this study. Participants in the study were 20 subjects with a history of TSF and 20 age- and mileage-matched control subjects with no previous lower extremity bony injuries. Kinematic and kinetic data were collected during overground running at 3.7 m.s(-1) using a six-camera motion capture system, force platform, and accelerometer. Variables of interest were vertical impact peak, instantaneous and average vertical loading rates, instantaneous and average loading rates during braking, knee flexion excursion, ankle and knee stiffness, and peak tibial shock. Tibial varum was measured in standing. Tibial area moment of inertia was calculated from tibial x-ray studies for a subset of runners. RESULTS: The TSF group had significantly greater instantaneous and average vertical loading rates and tibial shock than the control group. The magnitude of tibial shock predicted group membership successfully in 70% of cases. CONCLUSION: These data indicate that a history of TSF in runners is associated with increases in dynamic loading-related variables.

Adolescent↗
PubMed2005

Free moment as a predictor of tibial stress fracture in distance runners.

Stress fractures are a common and serious overuse injury in runners, particularly female runners. They may be related to loading characteristics of the lower extremity during running stance. Some tibial stress fractures (TSFs) are spiral in nature and, therefore, may be related to torque. Free moment (FM) is a measure of torque about a vertical axis at the interface with the shoe and ground. Increases in FM variables may be related to a history of TSF in runners. The purpose of this cross-sectional study was to investigate differences in FM between female distance runners with and without a history of TSF and, additionally, to investigate the relationship between absolute FM and the occurrence of TSF. A group of 25 currently uninjured female distance runners with a history of TSF (28+/-10 years, 46+/-15 km week(-1)) and an age- and mileage-matched control group of 25 healthy runners with no previous lower extremity fractures (26+/-9 years, 46+/-19 km week(-1)) participated in this study. Ground reaction forces and foot placement on the force platform were recorded during running at 3.7 ms(-1) (+/-5%). Peak adduction, braking peak and absolute peak FM and impulse were compared between groups using one-tailed t-tests. The predictive value of absolute peak FM was investigated via a binary logistic regression. All variables, except impulse, were significantly greater in runners with a history of TSF. Absolute peak FM had a significant predictive relationship with history of TSF. There is a significant relationship between higher values for FM variables and a history of TSF.

Adolescent↗
PubMed2005

The addition of the Protonics brace system to a rehabilitation protocol to address patellofemoral joint syndrome.

STUDY DESIGN: Randomized clinical trial. OBJECTIVES: To investigate the clinical efficacy of the addition of the Protonics system to a standard exercise-based patellofemoral rehabilitation protocol. BACKGROUND: The Protonics system has been suggested as an intervention for patients with patellofemoral pain syndrome (PFPS). However, the effects of this system have not been compared to the effects associated with traditional exercise-based rehabilitation alone. METHODS AND MEASURES: Seventeen of 34 females (mean age, 28 years; range, 13-55 years) diagnosed with PFPS were randomly assigned to wear the Protonics system while participating in a conventional exercise-based rehabilitation program. Functional and patient-reported outcome measures were evaluated, including Kujala score and the lateral step-up test. In addition, measurements of hip internal and external rotation, hip extension, and iliotibial band muscle length were compared between groups. RESULTS: Patients in both groups demonstrated improvement in Kujala score (P<.001), performance on the lateral step-up test (P<.001), and pain during the step-up test (P<.001) at the conclusion of the study. However, there was no difference between groups with respect to improvement in Kujala score (P = .33), step-up test performance (P = .47), or pain during the step-up test (P = .24). Patients using the Protonics system demonstrated greater gain in passive hip extension (P = .023) and increased hip external rotation motion (P = .017) at discharge versus patients treated with exercise alone. However, there was no difference in iliotibial band flexibility (P = .80) or hip internal rotation motion (P = .09) between groups. A greater proportion of patients in the Protonics group reported no pain with step-up testing at each 2-week interval. However, the 2.2 fewer visits required by patients in the Protonics group to meet discharge criteria did not achieve statistical significance (P = .08). CONCLUSIONS: Patients using the Protonics system demonstrated a shift in available hip rotation and increased passive hip extension flexibility. However, these changes were not outside the bounds of potential measurement error and did not translate into significant functional differences from a similar group treated with exercise alone. The economic implications of an average 2.2-visit decrease in treatment sessions per patient using the Protonics system are uncertain.

Adolescent↗
PubMed2004

Lower extremity joint coupling during running: a current update.

BACKGROUND: The relationship between lower extremity mechanics and injury is not well understood. However, joint coupling studies are beginning to emerge, which may lend further insight into running biomechanics. PURPOSE: To provide a current review of the research examining lower extremity joint coupling in running. SUMMARY: There are various techniques utilized to measure joint coupling, including joint timing, rearfoot eversion/tibial internal rotation ratios, continuous relative phase calculations, and vector coding. The study of joint coupling is of particular interest as it may pertain to running injuries. There is some evidence that joint coupling may be altered with orthotics and/or with footwear. Most studies have included a relatively small sample size and larger scale studies are needed to quantify normal ranges for many of the coupling measures. In addition, prospective studies are needed to clarify the relationship to injury. RELEVANCE: It is hoped that this update will serve as a review of the current state of thought regarding lower extremity joint coupling during running. As greater insight into the role of joint coupling in injuries is gained, more optimal intervention and prevention strategies can be developed to minimize injury risk.

Ankle Joint↗
PubMed2004

Foot and Ankle Research Retreat: concensus statement.

It is well recognized that the foot is a complex structure with 26 bones and over 30 articulations. Measuring its mechanics is a formidable task that is usually accomplished with a simplification of the system. The papers presented at this meeting provided some of the most current research in the area of multisegment foot modeling. The scientific discussions were rich as the small, intimate, and collegial environment encouraged an open flow of ideas. It was acknowledged that much work is still needed in the development of foot models to improve the measurement of foot mechanics. However, there was a strong sentiment among the participants to begin to apply these models to clinical problems. It was suggested that this be the focus of the next Foot and Ankle Research Retreat.

Ankle Joint↗