Reading Assignment: De Wall Malefijt et al., The Actual Status of - PowerPoint PPT Presentation

Reading Assignment: De Wall Malefijt et al., “The Actual Status of Acrylic Bone Cement in Total Hip Replacement,” Acta Orthop. Belg. 53: 52-58, 1987. Also, (re) read the Barich Ph.D. thesis section on fixturing for laboratory micromotion testing. Homework Assignment: Review the Davies et al. article and the Rimnac et al. article on the effects of cement centrifugation. Take a side in this controversy, and support your view by critical reasoning. Should PMMA be centrifuged? Write 2-3 pages, double-spaced 12 pt. Due Wed Oct 9 th .

Biomechanics of Acrylic Cement Fixation

O H CH 3 O H CH 3 C – O – C – C* C – O* + C = C H C = O H C = O O O CH 3 CH 3 H CH 3 H CH 3 O H CH 3 H CH 3 … C – C C – C C – O – C – C C – C* H H C = O H C = O H C = O C = O O O O O CH 3 CH 3 CH 3 CH 3 Polymerization Reaction

Setting Time: 8.5 mins. Property Changes Approaching Setting Time

Effect of Aging on PMMA Breaking Stress

Effect of Aging on PMMA Elastic Modulus

Regions of High Cement Calcar Stress

Cement-Bone Interface

Beam Theory Load Transmission through the Stem

Construct Stresses from Beam Theory M: unit moment D M : medullary diam. D P : prosthesis diam.

FEA of Construct Stesses

Distribution of Bending Stresses

High Intensity Cement Technique Lavage & As Cut Surface Preparation

High Intensity Cement Technique Lavage As Cut & Surface Preparation

Complete Contact Cement-Bone Interface Gap

Fatigue Test Specimen

Uncentrifuged Centrifuged Simplex P Cement Porosity

Maximum Initial Tensile Stress (MPa) Curves S-N

Survival Probability

Survival Probability

Uniaxial Tensile Test

Endurance Limit

Compact Tensile Specimen Fracture Toughness Test

Crack Propagation

Compact Tensile Specimen

Zimmer Simplex Palacos Gentimicin Fracture Toughness Comparisons

Fatigue Crack Propagation

Gel Permeation Chromatography Molecular Weight Distributions

Contraction upon Setting

Fracture around Particles

Fracture through Particles

Average Molecular Weights