RESUMO
Previously, 3D-printed bone grafts made of titanium alloy with bioactive coating has shown great potential for the restoration of bone defects. Implanted into a medullary canal titanium graft with cellular structure demonstrated stimulation of the reparative osteogenesis and successful osseointegration of the graft into a single bone-implant block. The purpose of this study was to investigate osseointegration of a 3D-printed degradable polymeric implant with cellular structure as preclinical testing of a new technique for bone defect restoration. During an experimental study in sheep, a 20 mm-long segmental tibial defect was filled with an original cylindrical implant with cellular structure made of polycaprolactone coated with hydroxyapatite. X-ray radiographs demonstrated reparative bone regeneration from the periosteum lying on the periphery of cylindrical implant to its center in a week after the surgery. Cellular structure of the implant was fully filled with newly-formed bone tissue on the 4th week after the surgery. The bone tissue regeneration from the proximal and distal bone fragments was evident on 3rd week. This provides insight into the use of bioactive degradable implants for the restoration of segmental bone defects. Degradable implant with bioactive coating implanted into a long bone segmental defect provides stimulation of reparative osteogenesis and osseointegration into the single implant-bone block.
RESUMO
INTRODUCTION: Ilizarov bone transport for large bone defect is challenging and may end in distraction osteogenesis failure. MATERIAL AND METHODS: Ten forearm and seven tibial defect cases with failed regeneration due to ischaemia during bone transport were studied retrospectively. Mean forearm and tibial defects were 5.5 ± 0.8 and 7.6 ± 1 cm respectively, or 22.3 ± 3.6 and 20 ± 2.3% as compared with healthy segments. Most patients had numerous previous operations (2.6 ± 0.5 and 3.4 ± 0.8 per patient, respectively), extensive scars locally and post-traumatic neuropathy. There were seven infected defects. Mechanical solutions used were (1) additional osteotomy and transport of the fragment to compact the ischaemic regenerate (10 forearms, 4 tibias) and (2) compaction of the connective tissue layer in the tibial regenerate with either two 5-mm steps (two cases) or gradually (one case). RESULTS: Bone integrity was restored in all the cases. Complete compensation of the defects was achieved in 12 patients with the first technique. Two patients with 8-cm ulna defects remained with residual discrepancy. In the forearm, mean compaction was 1.7 ± 0.4 cm. It took 25.7 ± 5.4 days followed by an average fixation period of 107.1 ± 11.8 days. In the tibia, mean longitudinal compaction by distraction measured 1.7 ± 0.8 cm. The second technique ended up with an acceptable shortening of 1 cm in two cases. Four centimeters were compressed in the third case gradually. CONCLUSION: The technical solutions used for mechanical effects on the ischaemic distraction regenerate resulted in its rescue and bone union in all the cases.