Hydroxylapatite and fluoroapatite coated intramedullary rods in canine femurs

The effect of plasma sprayed synthetic calcium phosphate coatings, specifically hydroxylapatite (HA) and fluoroapatite (FA), on the degree of bone/implant attachment strength was investigated using a canine femoral intramedullary rod model. Titanium grit-blasted rods were implanted bilaterally, right side uncoated and the left side coated, in 12 coonhounds. The degree of bone attachment strength was determined by measuring the push-out force to failure and histological analysis after 3, 6, and 12 months implantation. For each time period there were four canines with either HA or FA coated implants. At 3 months, the HA and FA coatings promoted greater bone attachment strength (FA less so than HA) when compared to uncoated surfaces. At 6 months, all surfaces were statistically equivalent (with the FA, on average, exhibiting a lower strength). At 12 months, the HA and uncoated surfaces were equivalent, with the FA having a significantly lower strength