Histological characteristics of bone in-growth of proximal humeral implants with different spatial structures

This study compares the longitudinal histological characteristics of proximal humeral implants with different spatial structures in rabbits. Thirty skeletally-mature male rabbits were divided into a trabecular structure group and regular hexahedron structure group according to the different spatial structures of a biological titanium alloy screw inserted into the greater tuberosity of the proximal humerus. Samples were collected 3, 6, and 12 weeks after the implantation surgery. Histological results showed that the amount of bone in-growth in the porous cavity of the screw implant increased over time. Quantitative analysis showed there was significantly more bone in-growth in the trabecular structure group than the classic structure group 3 weeks (25.4% ± 6.9% vs 19.6% ± 3.7%, P < 0.05) and 6 weeks (31.2% ± 1.7% vs 26.9% ± 5.3, P < 0.05) after the implantation surgery. No significant difference was detected between the two groups 12 weeks after the surgery (41.7% ± 2.5% vs 39% ± 4.1%, P > 0.05). Our data found that bone in-growth significantly differed among the three time points (P < 0.05) in both groups, but not between the implants with different spatial structures 12 weeks after the surgery.