Osseointegration of porous titanium and tantalum implants in ovariectomized rabbits: A biomechanical study

Abstract

BACKGROUND Today, biological fixation of uncemented press-fit acetabular components plays an important role in total hip arthroplasty. Long-term stable fixation of these implants depends on the osseointegration of the acetabular cup bone tissue into the acetabular cup implant, and their ability to withstand functional loads. AIM To compare the strength of bone-implant osseointegration of four types of porous metal implants in normal and osteoporotic bone in rabbits. METHODS The study was performed in 50 female California rabbits divided into non-ovariectomized (non-OVX) and ovariectomized groups (OVX) at 6 mo of age. Rabbits were sacrificed 8 wk after the implantation of four biomaterials [TTM, CONCELOC, Zimmer Biomet's Trabecular Metal (TANTALUM), and ATLANT] in a 5-mm diameter defect created in the left femur. A biomechanical evaluation of the femur was carried out by testing implant breakout force. The force was gradually increased until complete detachment of the implant from the bone occurred. RESULTS The breakout force needed for implant detachment was significantly higher in the non-OVX group, compared with the OVX group for all implants (TANTALUM, 194.7 ± 6.1 N vs 181.3 ± 2.8 N; P = 0.005; CONCELOC, 190.8 ± 3.6 N vs 180.9 ± 6.6 N; P = 0.019; TTM, 186.3 ± 1.8 N vs 172.0 N ± 11.0 N; P = 0.043; and ATLANT, 104.9 ± 7.0 N vs 78.9 N ± 4.5 N; P = 0.001). In the OVX group, The breakout forces in TANTALUM, TTM, and CONCELOC did not differ significantly ( P = 0.066). The breakout force for ATLANT in the OVX group was lower by a factor of 2.3 compared with TANTALUM and CONCELOC, and by 2.2 compared with TTM ( P = 0.001). In the non-OVX group, the breakout force for ATLANT was significantly different from all other implants, with a reduction in fixation strength by a factor of 1.9 ( P = 0.001). CONCLUSION TANTALUM, TTM, and CONCELOC had equal bone-implant osseointegration in healthy and in osteoporotic bone. ATLANT had significantly decreased osseointegration ( P = 0.001) in healthy and in osteoporotic bone.

Comparison of the Mechanical and Osseointegrative Performance of Porous Tantalum and Titanium for Acetabular Implantation in Total Hip Arthroplasty: A Literature Review

“…Contrastingly, Wu et al performed a pull-out test, with five PTi alloy structures with varying porosity levels, and found that the PTi cages with the two highest porosity levels demonstrated statistically significantly higher pull-out strengths than the PTa cage [11]. Bondarenko et al performed a test of implant break-out force, comparing the force required to detach an implant from both normal and osteoporotic bone tissue 8 weeks after implantation in four available PTi alloy implants against the PTa implant [2]. They found that in both normal and simulated osteoporotic bone, the breakout force of the tantalum was not significantly different than two of the three titanium alloy products, but one of the titanium alloy products withstood much lower break-out force than the other three [2].…”

“…Bondarenko et al performed a test of implant break-out force, comparing the force required to detach an implant from both normal and osteoporotic bone tissue 8 weeks after implantation in four available PTi alloy implants against the PTa implant [2]. They found that in both normal and simulated osteoporotic bone, the breakout force of the tantalum was not significantly different than two of the three titanium alloy products, but one of the titanium alloy products withstood much lower break-out force than the other three [2]. In a unique test that sought to compare the compression deformation resistance and stress-strain parameters of both scaffold types with that of pig bone, Fan et al performed uniaxial compression tests on the scaffolds and found that the deformation behaviour and stress-strain parameters of the tantalum scaffolds were closer to that of pig bone scaffolds than the titanium scaffolds [12].…”

“…Studies included in this review act as evidence of the potential significant contribution of pore morphology to observed results. For example, Bondarenko et al found that when testing several available titanium implants (of varying pore characteristics) with the PTa product, the titanium implant options with a porosity more similar to that of the tantalum implant tested displayed comparable results, while the other titanium implants with different porosity displayed varying results [2]. This demonstrated that it was the pore characteristics that affected the performance more drastically than the material itself.…”

“…In the early 1980s, the usage of cementless acetabular implants began to surpass that of traditional cemented components [1]. The transition to increased reliance on biological fixation through bone remodeling for stable long-term attachment of implant components generated significant experimentation in terms of the bone-facing implantation surface, especially in terms of morphological structure [2]. Given that aseptic loosening is the most common reason for THA revision, and that the number of both THA and revision THA procedures performed each year continues to increase [3], the identification of implant surfaces that maximize functional connection between bone and implant and consequently improve stability of the acetabular component is an important research objective.…”