【Abstract】 Objective To review the progress in the treatment of bone defect by porous tantalum implant. Methods Recent l iterature was extensively reviewed and summarized, concerning the treatment method of bonedefect by porous tantalum implant. Results By right of their unique properties, porous tantalum implants have achievedvery good results in the treatment of certain types of bone defects. Conclusion Porous tantalum implants have their ownadvantages and disadvantages. If the case is meet to its indications, this method can obtain a good effect. Porous tantalum implants provide a new way for the cl inical treatment of bone defects.
Objective To study the effectiveness of avascular necrosis of the femoral head treated by lesions clearance, compact bone grafting, and porous tantalum rod implantation. Methods Between March 2008 and May 2010, 14 patients (16hips) with avascular necrosis of the femoral head were treated by lesions clearance, compact bone grafting, and implantation of porous tantalum rod. Of 15 cases, 13 were male (15 hips) and 1 was female (1 hip) with a median age of 42.2 years (range, 18-73 years), including traumatic in 1 case (1 hip), alcohol ic in 4 cases (4 hips), and steroid-induced in 9 cases (11 hips); 3 hips were at Association Research Circulation Osseous (ARCO) stage I and 13 hips were at ARCO stage II. The Harris score was 51.89 ± 12.42, and the X-ray score was 31.88 ± 4.03. All the cases were diagnosed by X-ray films and MRI. The median disease duration was 2.5 years (range, 6 months to 7 years). All the patients accepted the operation of lesions clearance by slotting at the neck of femur, then, compact bone grafting, and implantation of porous tantalum rod were performed. The affected l imb could not bear weight loading at 1-3 months after operation and partly bear weight loading after 3 months of operation. Results Primary heal ing of incision was achieved in all patients and no compl ication occurred. The patients were followed up 24 months on average (range, 13-36 months). Two patients underwent total hip arthroplasty at 4 months and 2 years respectively because of even worsened pain and collapsed femoral heads; 12 patients achieved obvious pain rel ief with a survival rate 87.5%(14/16). The postoperative Harris score was 84.89 ± 17.96, showing significant difference when compared with preoperative score (t= —8.038,P=0.001). The X-ray examination showed definite ossification, increased density, regular arrangement of the trabeculae and no collapsed femoral head. The X-ray score was 32.19 ± 6.57, showing no significant difference when compared with preoperative score (t= —2.237, P=0.819). Conclusion Lesions clearance, compact bone grafting, and implantation of porous tantalum rod for avascular necrosis of the femoral head have a good short-term cl inical result.
ObjectiveTo observe the morphological characteristic by implanting domestic porous tantalum in rabbit patellar tendon and to evaluate biocompatibility features so as to provide experimental basis for porous tantalum used as interface fixation between tendon and bone. MethodsA total of 48 adult New Zealand white rabbits, male or female, weighing 2.5-3.0 kg, were selected. Porous tantalum flake (5 mm×5 mm×2 mm) was implanted in the left patellar tendon (experimental group) and the same size porous titanium flake in the right patellar tendon (control group). The animals were sacrificed at 2, 4, 8, and 12 weeks after implantation, then the specimens were harvested for gross observation, HE staining, scanning electron microscope (SEM) observation, and hard slices observation. ResultsNo animal died after operation. Porous tantalum was bonded closely with host tendon and no inflammatory reaction was found. Loose and thick fibrous capsule was observed at the beginning and became density and thinner in the end by microscope, showing significant difference between different time points in 2 groups (P<0.05), but no significant difference was found between 2 groups at different time points (P>0.05). The SEM observation showed that fibrous tissue attached to the surface and inner walls of porous tantalum at early stage, and extended on the material to reach confluence at late period, but the experimental group was more than the control group. Hard slices observation showed that the collagen fibrils were seen on porous tantalum interface with host tendon, and blood vessels grew into the pores. The control group and the experimental group showed no significant difference. ConclusionThe domestic porous tantalum has good biocompatibility. Connection and integration can be established between tendon and porous tantalum, and therefore it could be used in reconstruction of tendon-bone fixation device.
Objective To summarize the physicochemical properties, manufacturing technique, and biological characteristics of porous tantalum and its application progress and related problems in spinal surgery. Methods The domestic and foreign related literature about porous tantalum was summarized and analyzed. Results Porous tantalum is characterized by high porosity, high coefficient of friction, low elastic modulus, good biocompatibility, and superior osseointegration capability. Its manufacture methods include chemical vapor deposition and infiltration technique, foam impregnation and powder metallurgy technique, and heat treatment method. Good clinical efficacy has achieved in the application of porous tantalum interbody fusion Cage in cervical and lumbar fusion surgery, but there is controversy in spinal fusion rate, especially in cervical fusion rate. Surface modification can increase the osseointegration capability of porous tantalum and intervertebral bony fusion. Conclusion Good clinical efficacy has achieved in the application of porous tantalum interbody fusion Cage in lumbar fusion surgery, while there is a dispute in cervical fusion surgery. In order to further observation, studies with more patients and longer follow-up would be needed.
ObjectiveTo investigate the ability to repair osteochondral defect and the biocompatibility of porous tantalum loaded with bone morphogenetic protein 7 (BMP-7) by observing the effect of porous tantalum loaded with BMP-7 in repairing articular cartilage and subchondral bone defect. MethodsThe cartilage defect models of medial femoral condyle were established in 48 New Zealand white rabbits, which were randomly divided into 3 groups (n=16): porous tantalum material+BMP-7 (group A) and porous tantalum material (group B) were implanted into the right side of the medial femoral condyle; and no material was implanted as control (group C). The general condition of animals was observed after operation, then the specimens were harvested for gross observation, histological observation, and scanning electron microscope (SEM) observation at 4, 8, and 16 weeks after implantation, micro-CT was used to observe the cartilage and bone ingrowth and bone formation around porous tantalum at 16 weeks after implantation. ResultsNo animal died after operation and wound healed well. Gross observation showed that defects of groups A and B were covered with new cartilage with time, but earlier new cartilage formation and better repair were observed in group A than group B, no repair occurred at the site of bone defects, and defect surface was filled with fibrous tissue in group C. Cartilage repair gross score of group A was significantly higher than that of group B at 8 and 16 weeks (P < 0.05) but no significant difference was found between groups A and B at 4 weeks (P>0.05). SEM observation showed that the number of new cartilage and osteoblasts increased gradually with time, and the implanted material was gradually covered with the extracellular matrix, and the new bone tissue grew into the pores of the material; the neonatal bone tissue and extracellular matrix secretion of group A were significantly more than those of group B. The toluidine blue staining results showed that new cartilage and bone tissue gradually increased in the porous tantalum interface, and new bone trabecula formed and grew in the pores, the bone and the porous tantalum contact tended to close, and cartilage defect was gradually covered with cartilage like tissue, cartilage tissue and porous tantalum combined more closely in groups A and B at 4, 8 and 16 weeks. New cartilage and bone tissue of group A was more than that of group B. Micro-CT analysis indicated that the bone mineral density, trabecular thickness, trabecular number, and bone volume fraction of group A were significantly higher than those of group B at 16 weeks (P < 0.05), but the trabecular bone space was significantly lower than that of group B (P < 0.05). ConclusionThe domestic porous tantalum has good biocompatibility, domestic porous tantalum loaded with BMP-7 can promote the formation of a stable connection with the host and has a good effect on cartilage and subchondral bone defect repair.
Objective To investigate the effect of domestic porous tantalum encapsulated with pedicled fascial flap on repairing of segmental bone defect in rabbits’ radius. Methods A total of 60 New Zealand white rabbits (aged 6- 8 months and weighing 2.5-3.0 kg) were randomly divided into the experimental group and control group (30 rabbits each group). A 1.5 cm segmental bone defect in right radius was established as the animal model. The porous tantalums encapsulated with pedicled fascial flaps (30 mm×20 mm) were implanted in the created bone defect in the experimental group, and the porous tantalums were only implanted in the control group. X-ray films were observed at the day after operation and at 4, 8, and 16 weeks after operation. Specimens were taken out at 4, 8, and 16 weeks after operation for HE staining and toluidine blue staining observation. The maximum load force and bending strength were detected by three point bending biomechanical test, and the Micro-CT analysis and quantitative analysis of the new bone volume fraction (BV/TV) were performed at 16 weeks after operation to compare the bone defect repair abilityin vivo in 2 groups. Results All incisions healed by first intention without wound infection. At 4, 8, and 16 weeks after operation, the X-ray films showed that the implants were well maintained without apparent displacement. As followed with time, the combination between the implants and host bone became more and more closely, and the fracture line gradually disappeared. HE staining and toluidine blue staining showed that new bone mass and maturity gradually increased at the interface and inside materials in 2 groups, and the new bone gradually growed from the interface to internal pore. At 16 weeks after operation, the three point bending biomechanical test showed that the maximum load force and bending strength in the experimental were (96.54±7.21) N and (91.26±1.76) MPa respectively, showing significant differences when compared with the control group [(82.65±5.65) N and (78.53±1.16) MPa respectively] (t=3.715, P=0.004; t=14.801, P=0.000). And Micro-CT analysis exhibited that there were a large amount of new bone at the interface and the surface of implant materials and inside the materials. The new bone BV/TV in the experimental group (32.63%±3.56%) was significantly higher than that in control group (25.07%±4.34%) (t=3.299, P=0.008). Conclusion Domestic porous tantalum encapsulated with pedicled fascial flap can increase local blood supply, strengthen material bone conduction ability, and promote the segmental bone defect repair.
Objective To review the basical research progress of porous tantalum in bone tissue engineering. Methods The related basical research in fabrication, cytobiology, and surface modification of porous tantalum was reviewed and analyzed. Results The outstanding physiochemical properties of porous tantalum granted its excellent performance in biocompatibility and osteointegration, as well as promoting cartilage and tendon tissue restoration. However, the clinical utilization of porous tantalum is somehow greatly limited by the complex and rigid commercial fabrication methods and extraordinary high cost. Along with the publication of novel fabrication and surface modification technology, the application of porous tantalum will be more extensive, the promotion in bone tissue regeneration will be more prominent. Conclusion Porous tantalum has advantage in bone defect restoration, and significant breakthrough technology is needed in fabrication methods and surface modification.