We compared thirty-eight patients from three orthopaedic centres who had external fixation of the femur or the tibia. Patients were randomised to receive standard (tapered 5/6 millimeter) pins (Group A) or OsteoTite (hydroxyapatite coated tapered 5/6 mm) pins (Group B).

In Group A there were 18 patients who received 71 pins. Average age of the patients was 49±12 years. Three patients had external fixation in the femur and 15 in the tibia. External fixation was used in three types of treatment: fracture fixation (4), knee osteotomy (12), and bone-transport (2). Two different fixator frames were used: a unilateral fixator was mounted in 15 patients and a circular fixator in three patients. In Group B, 20 patients (average age: ± 48 years) received 86 pins. Four patients had external fixation in the femur and 16 in the tibia. External fixation was used in three types of treatments: fracture fixation in three patients, knee osteotomy in 13 patients, and bone-transport in four patients. Two different fixator frames were used: a unilateral fixator was mounted in 16 patients and a circular fixator in four patients.

No significant difference regarding sex, age, external fixation treatment type, external fixation frame, and length of treatment were observed between the two groups. Mean final pin insertion torque was 477 ± 214 Newton cm in Group A and 339 ± 184 in Group B (p< 0.01). Mean pin extraction torque was 205 ± 169 Newton cm in Group A and 532 ± 211 in Group B (p< 0.01). Pin extraction torque was significantly lower compared to the corresponding insertion torque in Group A (p< 0.01). Pin extraction torque was significantly higher compared to the corresponding insertion torque in Group B (p< 0.01). Pin tract infection rate was lower in Group B compared to Group A (p< 0.01).

This study shows that hydroxyapatite coating was clinically effective in the improvement of the bone pin interface strength of tapered pins. By using these pins, deterioration of the bone pin interface strength can be avoided and external fixation complications minimised.