STP953: Porous Polysulfone-Coated Femoral Stems

    DeMane, M
    Development manager of reconstructive products, research engineer, and advanced materials technology manager, Richards Medical Co., Memphis, TN

    Beals, NB
    Development manager of reconstructive products, research engineer, and advanced materials technology manager, Richards Medical Co., Memphis, TN

    McDowell, DL
    Associate professor of mechanical engineering, Georgia Institute of Technology, Atlanta, GA

    Georgette, FS
    Development manager of reconstructive products, research engineer, and advanced materials technology manager, Richards Medical Co., Memphis, TN

    Spector, M
    Professor, Emory University School of Medicine, Atlanta, GA

    Pages: 15    Published: Jan 1987


    Abstract

    Concerns about the metal ion release, high stiffness, and reduction in stem strength that are associated with porous metal coatings have prompted investigations of a relatively high-strength porous polymeric coating, porous polysulfone (PPSF). The present study was initiated in order to characterize the mechanical properties of PPSF and PPSF-coated titanium alloy and to evaluate the performance of PPSF as a coating on titanium alloy femoral stems in dogs. PPSF with various porosities was fabricated by sintering particles of Union Carbide P-1700 medical-grade polysulfone. Chemical coupling of PPSF to Ti-6Al-4V alloy specimens was achieved using silyl-reactive polysulfone. The shear strength of the PPSF/titanium alloy interface determined from push-out tests on coated cylindrical rods and transverse sections of the coated canine femoral stems was found to exceed 16 MPa. Tension and punch shear tests performed on the PPSF yielded values of 13 and 21 MPa, respectively. The relationship between strength and porosity characteristics was determined. Fatigue tests performed on PPSF-coated titanium femoral stems revealed no failure of the coating up to 1 million cycles. No difference between PPSF-coated and uncoated titanium specimens was found in the fatigue behavior. PPSF-coated titanium alloy canine femoral stems (32% porosity, 246 µm in average pore size) were implanted in 25 dogs. Evidence of loosening was found only in those animals in which the canal/fill ratio was low. No gross radiographic changes were found in the implanted femurs within the two-year postoperative period. Histology showed bone ingrowth fixation of the prostheses. Results of this investigation indicate that PPSF-coated femoral stems warrant continued investigation.

    Keywords:

    porous implants, porous materials, porous polymers, polysulfone, titanium alloy, femoral stems, orthopedic prostheses


    Paper ID: STP25243S

    Committee/Subcommittee: F04.93

    DOI: 10.1520/STP25243S


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