Affinos (Kuraray, Japan) is a β-tricalcium phosphate bone substitute with a unidirectional porous structure. This study aimed to investigate its efficacy on the healing process after filling for bone defects. Fifty-six patients who met the inclusion criteria were divided into cohort 1 (n = 30), including bones other than phalanges and metacarpal/tarsal bones, and cohort 2 (n = 26), including phalanges and metacarpal/tarsal bones. Semi-quantified scores for material resorption and trabeculation through the defect were evaluated with radiographs after surgery. In some patients, levels of bone metabolic markers were assessed. The values of resorption and trabeculation increased steadily with time, and trabeculation progressed compared with resorption in both cohorts. In cohort 1, multiple regression analyses showed that the diaphyseal lesion, smaller defect volume, and increased resorption values at 3 months were associated with increased values of resorption 12 months after surgery (R2 = 0.66, p < 0.001). The trabeculation values at 2 months were positively related to the trabeculation values 12 months after surgery (R2 = 0.35, p = 0.002). In cohort 2, the increased resorption values at 2 months and smaller defect volume significantly correlated with the increased resorption values 12 months after surgery (R2 = 0.58, p < 0.001). The ratio from the baseline of pyridinoline cross-linked carboxyterminal telopeptide of type I collagen at 3 months was negatively associated with the trabeculation values 12 months after surgery (R = - 0.791, p = 0.004). Evaluation of radiographic images and bone metabolic markers in the early postoperative period may predict the healing status at 12 months postoperatively in the defects followed by Affinos filling.
© 2022. The Author(s).