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.

BACKGROUNDThe thermal injury during bipolar radiofrequercy results in chondrocyte death that limits cartilage repair. The purpose was to determine the effects of various factors of bipolar radiofrequency on human articular cartilage after thermal injury, offering suitable working conditions for bipolar radiofrequency during arthroscopy.

METHODSOsteochondral explants from 28 patients undergoing total knee arthroplasty (TKA) in Department of Orthopaedic, Peking University Reople's Hospital from October 2013 to May 2014, were harvested and treated using bipolar radiofrequency in a light contact mode under the following conditions: various power setting of levels 2, 4 and 6; different durations of 2 seconds, 5 seconds and 10 seconds; irrigation with fluids of different temperatures of 4°C, 22°C, and 37°C; two different bipolar radiofrequency probes ArthroCare TriStar 50 and Paragon T2. The percentage of cell death and depth of cell death were quantified with laser confocal microscopy. The content of proteoglycan elution at different temperatures was determined by spectrophotometer at 530 nm.

RESULTSChondrocyte mortality during the treatment time of 2 seconds and power setting of level 2 was significantly lower than that with long duration or in higher level groups (time: P = 0.001; power: P = 0.001). The percentage of cell death after thermal injury was gradually reduced by increasing the temperature of the irrigation solutions (P = 0.003), the depth of dead chondrocytes in the 37°C solution group was significantly less than those in the 4°C and 22°C groups (P = 0.001). The proteoglycan elution was also gradually reduced by increasing the temperature (P = 0.004). Compared with the ArthroCare TriStar 50 group, the percentage of cell death in the Paragon T2 group was significantly decreased (P = 0.046).

CONCLUSIONSThermal chondroplasty with bipolar radiofrequency resulted in defined margins of chondrocyte death under controlled conditions. The least cartilage damage during thermal chondroplasty could be achieved with lower power, shorter duration, suitable temperature of irrigation solutions and chondroprotective probes. The recommendations for the use of bipolar radiofrequency to minimize cartilage damage could be achieved with a power setting of level 2, treatment duration of 2 seconds, suitable fluid temperature (closer to body temperature of 37°C) and chondroprotective Paragon T2 probes.

Arthroplasty, Replacement, Knee ; methods ; Cartilage, Articular ; surgery ; Catheter Ablation ; methods ; Cell Survival ; physiology ; Chondrocytes ; pathology ; Humans ; Microscopy, Confocal