Student research award in the graduate degree candidate category, 17th annual meeting of the society for biomaterials, scottsdale, AZ may 1–5,1991. A mechanical investigation of fluorapatite, magnesiumwhitlockite, and hydroxylapatite plasma‐sprayed coatings in goats

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Abstract
Ceramic coatings of fluorapatite (FA), magnesiumwhitlockite (MW), and hydroxylapatite (HA), and noncoated Ti‐6Al‐4V alloy (Ti) implants were evaluated before and after implantation in an animal study. Cylindrical plugs were coated by plasma‐spraying with FA, MW, and HA. X‐ray‐diffraction patterns showed for FA and HA a crystalline and for MW, an amorphous‐crystalline coating structure. The plugs were implanted into the right femora and left humeri of 16 adult goats. Follow‐up periods were 12 and 25 weeks. The in vivo results were evaluated using push‐out tests and scanning electron microscopy. There were significant differences in push‐out strengths between femur and humerus. The FA and HA implants showed significantly higher push‐out strengths than the MW and Ti alloy implants, especially for the 12 week follow‐up period. Furthermore, at 12 week follow‐up period. Furthermore, at 12 weeks, MW showed significantly lower push‐out strengths than Ti alloy. SEM‐investigation of the interfaces revealed that FA did not degrade while both MW and HA showed extensive degradation at 12 and 25 weeks. In addition, the interface after push‐out testing showed for the MW, HA, and Ti alloy implants to be fractured at the implant‐tissue interface and for the FA to be fractured at the coating‐titanium interface.