Reinforcement of PMMA bone cement with a continuous wire coil--a 3D finite element study.
The changes in the mechanical response of a bone cement reinforcement, comprised of a continuous stainless steel coil imbedded within the PMMA bone cement matrix surrounding the distal tip of the total hip arthroplasty, was investigated. To achieve this, a 3D finite element model depicting two and one half rotations of the coil imbedded within the cement at the distal tip was constructed. Ideally, the wire coil should reduce the radial, and to a greater extent, the hoop stresses developing within the cement and at the cement-stem interface. As a means of comparison, a control model of only bone cement was also built. For the radial stresses, the control had about 4.5 times the compressive stress of the reinforced models (0.039 (+/-0.00065) MPa vs. 0.0087 (+/-0.0012) MPa) at the cement-stem interface. The tensile hoop stresses were also 4.5 times higher (4.272 (+/-0.0147) MPa and 0.95 (+/-0.0052) MPa) for the control than for the reinforced models. This indicates that the wire coil reinforcement is effective in reducing the cement mantle's radial and, more importantly, the hoop stresses which may lead to the failure of both the cement and the implant as a whole.
Frigstad
J R
JR
Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City 52242, USA.
Park
J B
JB
D001843:Bone Cements / Q000737:chemistry*; D019245:Compressive Strength; D003198:Computer Simulation; D004548:Elasticity; D006622:Hip Prosthesis; D006801:Humans; D008768:Methylmethacrylates / Q000737:chemistry*; D008956:Models, Chemical; D011312:Pressure; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013193:Stainless Steel / Q000737:chemistry*; D013314:Stress, Mechanical; D013718:Tensile Strength
D001843:Bone Cements; D008768:Methylmethacrylates; D013193:Stainless Steel