title: The effect of phosphoric and phosphonic acid primers on bone cement bond strength to total hip stem alloys.
abstract: Aseptic loosening at alloy-cement interfaces constitutes a main failure mechanism of cemented total hip replacements (THR). As a potential solution we investigated the effect of metal primers containing phosphoric and phosphonic acid on shear bond strength (SBS) of bone cement to THR alloys (CoCrMo, TiAlNb) and pure tin (Sn) substrates (20×8×3 mm). Metal surfaces were modified by polishing or Al2O3blasting and primer application. Substrates without primer treatment served as references. Cylindrical cement pins (Ø 5mm) were polymerised onto substrate surfaces and aging (1, 5, 14 and 150 days) was simulated in aqueous NaCl solution (0.9%) before SBS determination and failure mode evaluation. Regardless of surface roughness and aging time, SBS for THR alloys and Sn was always significantly higher with primer treatment. Compared to untreated reference specimens (≤0.2MPa) SBS values increased even up to 350 fold (TiAlNb, 14 days) or 400 fold (CoCrMo, 5 days). In general, the phosphoric acid containing primer revealed significant higher SBS values on THR alloys compared to the phosphonic acid containing one. Al2O3blasted specimens showed generally higher SBS values than polished ones with the exception of Sn which showed high SBS values in general. With primer treatment on polished Sn a significant reduction of SBS could not be detected even up to 150 days, whereas THR alloys showed only an SBS improvement in the short term (≤14 days). A NaCl-pitting corrosion probably led to an increasing and durable SBS on polished Sn surfaces over time. Compared to modern THR in clinical practice that shows survival rates of 10, 15, 20 or more years, the receivable bond strength enhancements described in this study appeared to be very short. The improved SBS on THR alloys lasted only a few days before it was lost again. In contrast, the phosphoric acid primer treatment of polished Sn appeared to be very promising and may play a key role in further investigations dealing with the prevention of the stem-cement debonding in THR.
authors.affiliation: Laboratory for Biomechanics and Biomaterials (LBB), Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Strasse 1-7, 30628 Hannover, Germany; Laboratory of Biomechanics, Department of Orthopaedics, Justus-Liebig-University, Paul-Meimberg-Strasse 3, 35392 Giessen, Germany.
authors.forename: Eike
authors.initials: E
authors.lastname: Jakubowitz
authors.affiliation: Laboratory of Biomechanics, Department of Orthopaedics, Justus-Liebig-University, Paul-Meimberg-Strasse 3, 35392 Giessen, Germany.
authors.forename: Louisa
authors.initials: L
authors.lastname: Liehn
authors.affiliation: Laboratory of Biomechanics, Department of Orthopaedics, Justus-Liebig-University, Paul-Meimberg-Strasse 3, 35392 Giessen, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Jahnke
authors.affiliation: Laboratory of Biomaterials, Department of Prosthodontics, School of Dental Medicine, Justus-Liebig-University, Schlangenzahl 14, 35392 Giessen, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Wöstmann
authors.affiliation: Laboratory of Biomechanics, Department of Orthopaedics, Justus-Liebig-University, Paul-Meimberg-Strasse 3, 35392 Giessen, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Rickert
authors.affiliation: Laboratory of Biomaterials, Department of Prosthodontics, School of Dental Medicine, Justus-Liebig-University, Schlangenzahl 14, 35392 Giessen, Germany. Electronic address: Thomas.Niem@dentist.med.uni-giessen.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Niem
mesh_terms: D000497:Alloys; D019644:Arthroplasty, Replacement, Hip; D001843:Bone Cements; D006622:Hip Prosthesis; D006801:Humans; D008422:Materials Testing; D010757:Phosphorous Acids / Q000737:chemistry*; D033081:Shear Strength; D013499:Surface Properties
chemical_list: D000497:Alloys; D001843:Bone Cements; D010757:Phosphorous Acids
keywords: Aseptic loosening; Cement bond strength; Debonding; Metal primer; Passivation layer; Total hip replacement