Master of Science
Measuring knee motion during landing is a method to evaluate knee injury risk. Three-dimensional (3D) motion capture is inaccessible, and the Microsoft Kinect is an alternative to measure knee motion. The primary objective was to evaluate the influence of sex and body size on the validity of the Kinect to measure knee motion during landing. A secondary objective was to compare knee motion between females and males with high and low body mass index (BMI). We assessed frontal plane knee kinematics of 40 (10 per group of females and males with high and low BMI) participants during landing with the Kinect and 3D motion capture. Good agreement between methods was found for the knee ankle separation ratio across groups, but there was low agreement between methods for measuring knee abduction. The high BMI group regardless of sex had more knee abduction than the low BMI group when measured with motion capture.
Summary for Lay Audience
Traumatic knee injuries are common and result in missed playing time and long-term repercussions. The anterior cruciate ligament (ACL) is a knee structure that is important for stability during athletic tasks. ACL injuries require surgery and extensive physical rehabilitation. After rehabilitation, many athletes do not return to the same level of participation and are more likely to develop joint disease later in life.
Females have a higher incidence of ACL injury than males, which is partly due to physical characteristics such as bone shape, lower muscular strength, and different movement patterns. Additionally, females carry body mass around their hips and thighs compared with males who carry mass around the trunk. Therefore, females with greater mass may be disproportionately affected by poor movement patterns during landing. Individuals with larger body size have an increased risk of ACL injury. Furthermore, differences in body shape due to sex or size influence methods of assessing knee motion during landing.
This study evaluated the validity of a cost-effective and portable sensor that measures knee motion during landing relative to laboratory-based methods. There were two aims to the research: (1) to assess agreement between the portable sensor and laboratory-based motion capture for sex and body size groups, and (2) to compare knee motion during landing between females and males of different body sizes. We found that the sensor agreed with the motion capture for assessing knee position relative to the ankles, but not for measuring the angle between the thigh and shin. Furthermore, body size but not sex influenced the accuracy of the portable sensor. We also found that individuals with greater body size landed with more inward knee motion than individuals with lower body size.
The findings from this study may guide the use of the portable sensor for identifying individuals at greater risk of knee injury. Exercise programs have shown success in lowering knee injury rates by improving strength and coordination. Therefore, the portable sensor may be useful for identifying individuals who may benefit from preventative exercises, but caution is recommended when measuring knee motion in those with larger body size.
Neufeld, Jillian, "The Influence Of Sex And Body Size On The Validity Of The Microsoft Kinect For Measuring Knee Motion During Landing" (2023). Electronic Thesis and Dissertation Repository. 9482.
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