Clinical and histomorphometrical study on titanium dioxide-coated external fixation pins

Hironobu Koseki,¹ Tomohiko Asahara,¹ Takayuki Shida,¹ Itaru Yoda,¹ Hidehiko Horiuchi,¹ Koumei Baba,² Makoto Osaki<sup>1

1</sup>Department of Orthopedic Surgery, Graduate School of Medicine, Nagasaki University, ²Industrial Technology Center of Nagasaki, Nagasaki, Japan

Background: Pin site infection is the most common and significant complication of external fixation. In this work, the efficacy of pins coated with titanium dioxide (TiO2) for inhibition of infection was compared with that of stainless steel control pins in an in vivo study.
Methods: Pins contaminated with an identifiable Staphylococcus aureus strain were inserted into femoral bone in a rat model and exposed to ultraviolet A light for 30 minutes. On day 14, the animals were sacrificed and the bone and soft tissue around the pin were retrieved. The clinical findings and histological findings were evaluated in 60 samples.
Results: Clinical signs of infection were present in 76.7% of untreated pins, but in only 36.7% of TiO₂-coated pins. The histological bone infection score and planimetric rate of occupation for bacterial colonies and neutrophils in the TiO₂-coated pin group were lower than those in the control group. The bone-implant contact ratio of the TiO₂-coated pin group was significantly higher (71.4%) than in the control pin group (58.2%). The TiO₂ was successful in decreasing infection both clinically and histomorphometrically.
Conclusion: The photocatalytic bactericidal effect of TiO₂ is thought to be useful for inhibiting pin site infection after external fixation.

Keywords: titanium dioxide, external fixation, bactericidal activity, Staphylococcus aureus