Mini project 3 hip problem
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Transcript of Mini project 3 hip problem
Mini Project 3
Mini Project 3: Orthobullets
Jensen Williams, Natalie Ivey, Timothy Lindquist
Question
Summarize the problemWhat is J when the acetabulum is moved medially on a patient standing on their right leg given the information on the next slide?
Collect InformationNon-medial Distance A = 50 mm = 0.05 mDistance B = 100 mm = 0.1 mJ = Resultant Hip Joint Force = 1800 NAT = Abductor Tension = 1200 NFBW = Body weight at pubis = 5/6 x BW = 5/6 x 720 N = 600 N
Medial Distance A = 50 mm = 0.05 mDistance B = 50 mm = 0.05mJ = Resultant Hip Joint Force = UNKNOWNAT = Abductor Tension = UNKNOWNFBW = Body weight at pubis = 5/6 x BW = 5/6 x 720 N = 600 N
Assumptions?Assumptions for this problem include: 1) This material exhibits ideal behavior for the models used. This is termed a LEHI material.2) 2D problem: this simplifies calculation of forces3) Ignore all other forces: just focusing on the hip.4) Hip in static equilibrium: allows for calculations to be set to zero.5) Forces are perpendicular to moment arm: this eliminates the need for force calculations regarding different angles, although some problems might contain angles this one does not.
Isolate the area to be analyzed before drawing the free body diagram
Draw the free body diagram
Pick a point to take moment about
Visualize the moments
Solve for equilibrium of moments
Continue to solve for J
Alternate Way OR A Great Checking Mechanism
Isolate the spot to analyze moment
Visualize the moments
Write moment equilibrium equations
Continue to solve the equations
Equilibrium in y direction
Looking BackEliminating Answers
M = r x FM = r x FFcJM = r x FRed Medial hip body weight momentGreen Medial and nonmedial hip moment from JDark Blue Nonmedial hip moment from body weightFc