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15 Cards in this Set
- Front
- Back
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What two structures does the abductor complex consist of? What is more medial?
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Gluteus medius
Gluteus minimus Minimus is more medial |
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How is offset measured?
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From the center of the femoral head to the greater trochanter
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How is neck length measured?
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Center of head to lesser trochanter
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What are the two potential disadvantages of decreased neck length?
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Lax abductor complex
Trochanteric impingement |
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What surgical option exists if THA components are well aligned but remain unstable?
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Trochanteric advancement
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What three surgical options are available in abductor deficient patients?
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Large head
Constrained (polyethelene) PE liner Hemiarthroplasty |
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What effect on hip joint reaction force (JRF) does each of the following factors have? Trendelenburg gait?
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Decreased abductor moment and decreased JRF
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A contralateral cane?
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Decreased JRF
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A varus positioned femoral implant? What is the downside of varus?
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Decreased JRF
Downside: increased shear |
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What is the advantage of increased offset? What is the disadvantage?
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Decreased JRF
Increased loosening |
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Quick review: What are four key ways to decrease hip joint reaction force?
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Cane in contralateral hand
Trendelenburg gait Varus component High offset |
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With a valgus positioned femoral component, what is the effect on offset?
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Decreased offset
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. . . on joint reaction force?
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Increased JRF
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. . . on shear?
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Decreased shear
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Therefore, is a varus or valgus femoral implant position preferred and why?
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Valgus
Varus placement results in loosening because PMMA poorly resists shear |
