Date of Award

Summer 2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Medical Diagnostic & Translational Sciences

Program/Concentration

Mechanical Engineering

Committee Director

Stacie I. Ringleb

Committee Director

Sebastian Y. Bawab

Committee Member

Joshua T. Weinhandl

Call Number for Print

Special Collections; LD4331.E56 C68 2012

Abstract

Knee moments are greater in individuals who climb Navy ship ladders than in people climbing stairs. Because it is known that people who climb stairs frequently are at greater risk for osteoarthritis and that people in the Navy report higher incidences of knee pain, it was hypothesized that the internal joint reaction forces during the sailor's descent of a ship ladder would be greater than internal joint reaction forces of gait and stair climbing. Dimensions of a commonly used Navy ship ladder were collected and a replica was constructed. The replica was instrumented to collect 3D kinematics and kinetics during its descent. Three dimensional dynamic models of three individuals descending the replica Navy ship ladder were created. OpenSim (SimTK, Stanford University) was used to create the dynamic model using the kinematic marker trajectories and six degree of freedom ground reaction forces as input. It was also used for the post analysis in conjunction with Matlab (MathWorks, Natick, MA). The dynamic model's quadriceps to hamstring (Q:H) strength ratio was adjusted from a 5:3 ratio to 2:1 and 4:3 to see how it would affect the internal joint reaction force at the knee.

The peak average external knee moment was 1.9 Nm/Kg. The calculated external knee moments were greater than published knee moments on traditional stairs. The internal joint reaction forces at the knee were calculated from the dynamic model using the Analysis tool in OpenSim. The average peak vertical and anterior internal joint reaction force at the knee were 4.05 x BW and 5.46 x BW. These internal forces were greater than internal knee joint reaction forces from walking on level ground and traditional stairs found in the literature. Changing the Q:H strength ratio did not alter the internal joint reaction force, however future studies should be used to determine if the contact force across the medial and lateral joint surfaces of the knee are altered when the Q:H ratio is changed.

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DOI

10.25777/jhyr-zj34

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