Waris E, MD (1,2), Ashammakhi N, MD, PhD, FRCSEd (3), Happonen H, MSc (4), Raatikainen T, MD, PhD (5), Kaarela O, MD, PhD (3), Törmälä P, PhD, BMS (4), Santavirta S, MD, PhD (6), and Konttinen YT, MD, PhD (1, 2)

1. Institute of Biomedicine/Anatomy, Biomedicum Helsinki, University of Helsinki, Finland;
2.ORTON Research Institute, Invalid Foundation, Helsinki, Finland;
3. Division of Plastic Surgery, Department of Surgery, Oulu University Hospital, Finland;
4. Institute of Biomaterials, Tampere University of Technology, Finland;
5. Clinic of Hand Surgery, Department of Surgery, Helsinki University Central Hospital, Finland;
6. Department of Orthopedics and Traumatology, Helsinki University Central Hospital, Finland; and Department of Medicine/Invärtes medicin, Helsinki University Central Hospital, Finland.

Abstract
Bioabsorbable implants offer an attractive alternative to metallic ones to stabilize small bone fractures in hand. Self-reinforced (SR) bioabsorbable miniplating for metacarpal (MC) fractures was studied in cadaver bones and compared with standard metallic fixation methods. One hundred and twelve fresh-frozen human MC bones underwent three-point bending and torsional loading after transverse osteotomy followed by fixation using seven different methods: dorsal and dorsolateral 2.0 mm SR polylactide-polyglycolide (PLGA) 80/20 plating, dorsal and dorsolateral 2.0 mm SR poly-L/DL-lactide (P(L/DL)LA) 70/30 plating, dorsal 1.7 mm titanium plating, dorsal 2.3 mm titanium plating, and crossed 1.25 mm Kirschner wires. In apex dorsal and palmar bending, dorsal SR-PLGA and SR-P(L/DL)LA plates provided stability comparable with dorsal titanium 1.7 mm plating. When the bioabsorbable plates were applied dorsolaterally, apex palmar rigidity was increased and apex dorsal rigidity was decreased. Bioabsorbable platings resulted in higher torsional rigidity than 1.7 mm titanium plating and in failure torque comparable with 2.3 mm titanium plating. In conclusion, low-profile SR-PLGA 80/20 and SR-P(L/DL)LA 70/30 miniplates provide satisfactory biomechanical stability for MC fixation. These findings suggest that bioabsorbable miniplating can be safely used in clinical stabilization of MC and phalangeal fractures.