Loading improves anchorage of hydroxyapatite implants more than titanium implants

Abstract

Roentgen Stereophotogrammetric Analysis (RSA) studies have shown that the quality of the early fixation of implants has a dominant effect on their long-term function. To evaluate methods to improve their fixation, we examined the influence of mechanical loading and surface coating on the quality of the bone-implant interface. We compared the fixation of a cylindrical, stable 6.0 mm implant initially surrounded by a 0.75 mm concentric gap, after 4 weeks of loaded or unloaded conditions. Two types of surfaces were analyzed: plasma sprayed hydroxyapatite (HA) and plasma sprayed titanium (Ti). The histomorphometric evaluation showed that HA implants had greater bone coverage than Ti implants, and this coverage was further increased under loaded conditions only for HA. Furthermore, loading reduced the fibrous tissue coverage for the HA implants, while it increased fibrous tissue coverage for Ti implants. These findings were in agreement with pushout results showing that HA implants had greater shear strength, stiffness, and energy than Ti implants, and (except for energy) these parameters were further increased under loaded conditions only for HA. In addition, because the two implant surfaces exhibited a different relative response to load, it is important to evaluate new surfaces under the more clinically relevant loaded condition.

Osseointegration of alumina with a bioactive coating under load-bearing and unloaded conditions

“…Hydroxyapatite revealed greater bone contact than titanium. Bone contact was further increased under loaded conditions only for hydroxyapatite implants, while loading increased fibrous tissue coverage for titanium implants [32]. Similar results were found in the present study: The two implant surfaces revealed a different response to load.…”

“…A reason for the controversial results of coated Al 2 O 3 in the both implant models, however, could be the different mechanical conditions at the implantation sites. Mouzin et al [32] reported that loading improves anchorage of hydroxyapatite implants more than titanium implants. The authors compared stable but mechanically loaded and unloaded implants.…”

Alendronate treatment in the revision setting, with and without controlled implant motion

“…Following intravenous administration of alendronate (miniosmotic pump; 0.01 mg/kg/day), bone volume was similar to counterparts not exposed to particles. While these results are encouraging, it should be noted that the experimental protocols did not allow mechanical stability or weight bearing to be controlled (Mouzin 2001).…”

Calcium phosphate sol–gel-derived thin films on porous-surfaced implants for enhanced osteoconductivity. Part II: Short-term in vivo studies

“…Perizzolo et al [33] reported on an in vitro study in which a synergistic effect was observed between topography (micromachined grooved surfaces) and chemistry (Ca-P coatings) for the initiation of bonelike nodule formation. Soballe et al reported on the benefits of an HA coating over a Ti plasma-sprayed layer that results in a very irregular surface topography [34]. The application of plasma-sprayed 'HA' (actually a mixture of different Ca-P phases) over sintered porouscoated implants (sintered Ti fibres) was reported by Rivero et al [25] to give faster bone ingrowth.…”