The effect of surface preparation on metal/bone cement interfacial strength

Abstract

This study is concerned with finding practical ways for strengthening metal/bone cement (M/BC) interfaces via surface alterations and identifying fundamental mechanisms underlying M/BC adherence. Shear strengths have been inferred from torsion tests using shear-lag analysis. The variables examined with regard to their effects on interfacial strength are substrate material, surface roughness, interface porosity, passivation and sterilization, surface cleaning procedures, and use of bone cement precoated metals. M/BC interfaces can be substantially strengthened by applying the bone cement to the metal with high pressure. This would be a practical way to strengthen interfaces for precoated implants. The acrylic polymerized in vivo would employ the usual low pressure method. Otherwise, the main method for improving M/BC interfaces is through changing surface topography. Cleaning or chemical treatments have relatively minor effects. Roughened surfaces, as expected, produce stronger interfaces. Dramatic strength improvements occurred with a porous arc plasma sprayed layer on the substrate. Surprisingly, highly polished surfaces also improve interface strength (compared to less polished surfaces). The hypothesis is advanced that M/BC adherence depends upon superposition of mechanical interlocking and atomic interaction effects, with the latter predominating for finer finishes and vice versa. Differences exist between materials which are independent of roughness.

Surface roughness of debonded straight-tapered stems in cemented THA reduces subsidence but not cement damage

“…Cementing techniques [16], surface roughness patches [17], textures [18], and pre-coatings [7,[19][20][21] have been considered to create a reliable and endurable fixation. However, as long as the bond between the stem and the cement mantle cannot be secured for the complete lifetime of the implant, not just the bonding strength, but also the fail-safe mechanism against the effects of debonding should be considered.…”

Fluid flow around model femoral components of differing surface finishes: In vitro investigations

“…A study of the bonding forces between stems with different surface finishes and PMMA found an unexplained increase in the bonding force as the stem became smoother (Bundy and Penn 1987). The increased bonding force between increasingly smooth surfaces and the PMMA was ascribed to an atomic (or chemical) interaction.…”

“…An increased electrostatic interaction between the metal and bone cement due to van der Waals forces could be involved." (Bundy and Penn 1987).…”

Effect of antibiotic loading on the shear strength at the stem–cement interface (Shear strength of antibiotic loaded cement)

“…A roughness of 1 μm was preferred in this study, depending on the findings of previous studies about shear strength and clinical outcome. Around the level of 1 μm, an acute increase in SCI stability was reported, reaching the estimated in vivo shear stresses [4,7]. Although higher levels of roughness provide higher shear strength values, they are not preferred in clinical settings since rough stems have been shown to have higher failure rates compared to polished stems [6].…”

“…Shear strength of the SCI is affected by several factors including the stem's surface roughness [4,7,20,21], preheating the stem [12,21], pre-chilling the cement monomer [13], the type of cement used [20], precoating of the stem [1,17], metal type [4], and even the loading rate [22]. Possible effects of all these factors were eliminated in our study, using a standard protocol for all groups.…”