Relative effects of age on implant integration in a rat model: A longitudinal in vivo microct study

Abstract

The effect of age on implant fixation in bone is not always considered during the design of preclinical models. The decision on animal's age is often related to practical or historical reasons, which ultimately may affect the reproducibility of results. This study aimed to quantify the effect of age by monitoring the fixation of contrast‐enhanced PEEK screws in rats, hypothesizing that the kinetics of fixation is impaired in older animals but that age effects are less severe than osteoporotic effects. The time course of implant fixation was investigated in healthy rats at 24, 40, and 60 weeks of age; and in ovariectomized rats. Implant fixation was monitored using in‐vivo microCT and dynamic histomorphometry during 1 month. The rats were euthanized 28 days post screw insertion. The data was analyzed both in absolute value and after normalization to baseline bone mass. In absolute terms, greater age had a detrimental effect on bone implant contact, bone fraction, implant stiffness, and bone remodeling but less than ovariectomy. Interestingly, once data was normalized to baseline bone mass this effect disappeared, suggesting that the physiologic response to implant placement was not affected by age. In conclusion, implant fixation kinetics is less affected by age than by baseline bone mass in this rat model. Animals of different ages can therefore be compared but data must be construed relatively to baseline bone mass and not in absolute terms. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 9999:1–12, 2018.

Impact of low bone mass and antiresorptive therapy on antibiotic efficacy in a rat model of orthopedic device‐related infection

“…Consent to perform this study was granted by the ethical committee of the canton of Graubünden in Switzerland (approval number 05/2015) and was carried out in an AAALAC‐accredited research institute. Our previously reported model of ODRI in the rat proximal tibia was used, 20,21 utilizing polyetheretherketone (PEEK) screws. A total of 72 rats were included in the study (overview of grouping shown in Table 1).…”

“…Skeletally mature, adult female, specific pathogen‐free Wistar rats, purchased from Charles River at 9–10 weeks of age, were used in this study after a minimum 2‐week acclimatization period. Animal monitoring, care, and potential exclusion criteria were as previously described 20,21 . Animals were randomly allocated to either OVX or non‐OVX groups and subsequent subgroupings of infected/noninfected.…”

“…Anesthesia and surgery were performed as described previously 20,21 . In brief, OVX surgery was performed at 12 weeks of age followed by a 12‐week period to allow bone mass loss before screw insertion surgery at 24 weeks.…”

Evaluation of the bone morphology around four types of porous metal implants placed in distal femur of ovariectomized rats

“…In order to study osseointegration and fixation properties, animal models were established for material evaluation [24]. It has been established that osteoporosis can affect the fixation and osseointegration of implants [25,26], in particular, giving the different responses of osteoporotic cortical and trabecular bone to material implantation [27]. Therefore, establishing the structural features of bone tissue around porous implant materials is important for selecting a particular material for use in patients with low bone mineral density.…”

Evaluation of the Bone Morphology Around Four Types of Porous Metal Implants Placed in Distal Femur of Ovariectomized Rats

“…In order to study osseointegration and xation properties animal models were established for material evaluation [24]. It has been established that osteoporosis can affect the xation and osseointegration of implants [25,26], in particular, giving the different response of osteoporotic cortical and trabecular bone to material implantation [27]. Therefore, establishing the structural features of bone tissue around porous implant materials is important for selecting a particular material for use in patients with low bone mineral density.…”