Osseointegration of biochemically modified implants in an osteoporosis rodent model

Abstract

The present study examined the impact of implant surface modifications on osseointegration in an osteoporotic rodent model. Sandblasted, acid-etched titanium implants were either used directly (control) or were further modified by surface conditioning with NaOH or by coating with one of the following active agents: collagen/chondroitin sulphate, simvastatin, or zoledronic acid. Control and modified implants were inserted into the proximal tibia of aged ovariectomised (OVX) osteoporotic rats (n = 32/group). In addition, aged oestrogen competent animals received either control or NaOH conditioned implants. Animals were sacrificed 2 and 4 weeks post-implantation. The excised tibiae were utilised for biomechanical and morphometric readouts (n = 8/group/readout). Biomechanical testing revealed at both time points dramatically reduced osseointegration in the tibia of oestrogen deprived osteoporotic animals compared to intact controls irrespective of NaOH exposure. Consistently, histomorphometric and microCT analyses demonstrated diminished bone-implant contact (BIC), periimplant bone area (BA), bone volume/tissue volume (BV/ TV) and bone-mineral density (BMD) in OVX animals. Surface coating with collagen/chondroitin sulphate had no detectable impact on osseointegration. Interestingly, statin coating resulted in a transient increase in BIC 2 weeks post-implantation; which, however, did not correspond to improvement of biomechanical readouts. Local exposure to zoledronic acid increased BIC, BA, BV/TV and BMD at 4 weeks. Yet this translated only into a non-significant improvement of biomechanical properties. In conclusion, this study presents a rodent model mimicking severely osteoporotic bone. Contrary to the other bioactive agents, locally released zoledronic acid had a positive impact on osseointegration albeit to a lesser extent than reported in less challenging models.

A systematic review and meta‐analysis on the influence of biological implant surface coatings on periimplant bone formation

“…6 Yet another surface modification to further stimulate osseointegration is the coating of implant surfaces with biological components. [7][8][9] For bone, these may be organic as well as inorganic in nature, and both can potentially influence cellular activity during periimplant healing. In this context, many different types of surface coatings have been analyzed in recent years.…”

Bone regenerating effect of surface-functionalized titanium implants with sustained-release characteristics of strontium in ovariectomized rats

“…39 Anesthesia was initialized with Isoflurane (Forane ® ; Abbott Laboratories, Abbott Park, IL, USA) with subsequent intramuscular administration of Ketaminol (Ketamin ® ; Dr E Graeub AG, Bern, Switzerland; 100 mg/kg body weight) and Xylasol (Xylazin ® ; Dr E Graeub AG; 10 mg/kg body weight) to assure sufficient narcosis. An overview of the surgical procedure is shown in Figure 2.…”

Collagen type I coating stimulates bone regeneration and osteointegration of titanium implants in the osteopenic rat

“…biphosphonates) or anabolic agents (i.e. parathyroid hormone or bone morphogenetic protein) immobilised on the material surface in the osteoporotic condition, but, to the best of the authors' knowledge, few published papers have evaluated material surface functionalisation with collagen type I in an osteoporotic animal model [21,22].…”

“…study design, site of implant, age of the animal, experimental times, different techniques employed to modify material surfaces both topographically than biochemically) are important variables that can influence the results. For example, Stadlinger et al [22] found no detectable impact on the osteointegration parameter (BIC, BI and BV/TV and pull-out test) exerted by a collagen/chondroitin sulphate titanium coating at either two or four weeks after implant. In another in vivo study, Alghamdi et al [21] compared a CaP and collagen type I coated Ti implant to an uncoated one both in healthy and osteoporotic conditions, by adopting a similar experimental set up.…”