The aim of this study was to explore whether adverse reactions would occur during the material’s degradation period even at a later time point after surgery and whether these phenomena were clinically significant and would influence the final outcome. 12 unstable, displaced metacarpal fractures in 10 patients (7 males, 3 females; mean age 36.4 y, range 18–75 y) were treated with the Inion® OTPSTM Biodegradable Mini Plating System. 9 patients (10 fractures) were available for follow-up (mean 25.6 months, range 14 to 44 m). For patients without appearance of foreign body reaction the minimum follow-up time was 24 months Patients were examined both radiologically to evaluate fracture healing, and clinically by completing the DASH-score and a visual analogue scale for pain assessment. Grip strength, finger strength and range of motion of metacarpo-phalangeal and interphalangeal joints were measured. Fracture healing occurred uneventfully in all patients within six weeks. The most important complication was a foreign body reaction observed in 4 of our patients more than a year postoperatively. All were re-operated and had the materials removed. Histological examination confirmed the diagnosis of aseptic inflammation and foreign body reaction. Although internal fixation of metacarpal fractures by using bioabsorbable implants is a satisfactory alternative fixation method, patients should be advised of this possible late complication and should be followed postoperatively for at least one and a half year, possibly longer.