Abstract
Background Surgical fixation of implants into bone for the correction of bone deformities or defects is a traditional approach for skeletal stabilization. Important measures of efficacy of implants include implant stability and osseointegration—the direct interaction between living bone and an implant. Osseointegration depends on successful implant placement and subsequent bone remodeling. This study utilized osseodensification drilling (OD) in a low bone density model using trabecular metal (TM) implants. Material and Methods Three osteotomy sites, Regular, OD-CW (clockwise), and OD-CCW (counterclockwise), were prepared in each ilium of three female sheep. Drilling was performed at 1100rpm with saline irrigation. Trabecular metal (TM) (Zimmer®, Parsippany, NJ, USA) implants measuring 3.7mm in diameter x 10mm length were placed into respective osteotomies. A three-week period post-surgery was given to allow for healing to take place after which all three sheep were euthanized and the ilia were collected. Samples were prepared, qualitatively and quantitatively analyzed using histology micrographs and image analysis software (ImageJ, NIH, Bethesda, MD). Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were quantified to evaluate the osseointegration parameters. Results All implants exhibit successful bone formation in the peri-implant environment as well as within the open spaces of the trabecular network. Osseointegration within the TM (quantified by %BIC) as a function of drilling technique was more pronounced in OD samples(p>0.05). The %BAFO however shows a significant difference (p=0.036) between the CCW and R samples. Greater bone volume and frequency of bone chips are observed in OD samples. Conclusions The utilization of OD as a design for improved fixation of hardware was supported by increased levels of stability, both primary and secondary. Histological data with OD provided notably different results from those of the regular drilling method. Key words:Osseodensification drilling, trabecular tantalum metal, osteotomies, implants, subtractive drilling.
Highlights
Successful integration of an implant with bone may be influenced by factors such as surgical protocol (presence of irrigation, speed (RPM), drilling sequence, etc.), device geometrical configurations, or surface chemistry modifications (e.g. chemical coating such as calcium phosphate (CaP) crystals or hydroxyapatite) [1,2]
No evident failure of implants was observed at time of necropsy. - Histomorphometric Analysis Analyzing the level of integration within the trabecular metal portion of the implant as a function of drilling technique showed an, not statistically different, increasing trend, of %Bone-to-implant contact (BIC) in samples drilled with osseodensification drilling (OD) relative to samples prepared through the conventional R drilling instrumentation (Fig. 2) (p>0.05)
Osseodensification is a novel approach to osteotomy preparation for implant placement that has shown to improve parameters such as primary stability, osseointegration, and secondary stability—all indicators of long-term implant survival from the time of fixation to the healing period
Summary
Successful integration of an implant with bone may be influenced by factors such as surgical protocol (presence of irrigation, speed (RPM), drilling sequence, etc.), device geometrical configurations, or surface chemistry modifications (e.g. chemical coating such as calcium phosphate (CaP) crystals or hydroxyapatite) [1,2]. The use of hydroxyapatite (HA)-coated implants was implemented to take advantage of the osteoconductive nature of the mineralized matrix, but HA has been subject to rapid wear which can diminish the implant’s osseointegrative potential [2,10]. Another implant modification, which has an influence on osseointegration is the surface roughness/texture of the implant [11]. The bone fragments have shown to significantly increase primary stability [21], while simultaneously functioning to bridge the gap created between the implant surface and osteotomy wall. Osseointegration within the TM (quantified by %BIC) as a function of drille764
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