Potential use of porous titanium-niobium alloy in orthopedic implants: preparation and experimental study of its biocompatibility in vitro.

BACKGROUND: The improvement of bone ingrowth into prosthesis and enhancement of the combination of the range between the bone and prosthesis are important for long-term stability of artificial joints. They are the focus of research on uncemented artificial joints. Porous materials can be of potential use to solve these problems. OBJECTIVES/PURPOSES: This research aims to observe the characteristics of the new porous Ti-25Nb alloy and its biocompatibility in vitro, and to provide basic experimental evidence for the development of new porous prostheses or bone implants for bone tissue regeneration. METHODS: The Ti-25Nb alloys with different porosities were fabricated using powder metallurgy. The alloys were then evaluated based on several characteristics, such as mechanical properties, purity, pore size, and porosity. To evaluate biocompatibility, the specimens were subjected to methylthiazol tetrazolium (MTT) colorimetric assay, cell adhesion and proliferation assay using acridine staining, scanning electron microscopy, and detection of inflammation factor interleukin-6 (IL-6). RESULTS: The porous Ti-25Nb alloy with interconnected pores had a pore size of 200 µm to 500 µm, which was favorable for bone ingrowth. The compressive strength of the alloy was similar to that of cortical bone, while with the elastic modulus closer to cancellous bone. MTT assay showed that the alloy had no adverse reaction to rabbit bone marrow mesenchymal stem cells, with a toxicity level of 0 to 1. Cell adhesion and proliferation experiments showed excellent cell growth on the surface and inside the pores of the alloy. According to the IL-6 levels, the alloy did not cause any obvious inflammatory response. CONCLUSION: All porous Ti-25Nb alloys showed good biocompatibility regardless of the percentage of porosity. The basic requirement of clinical orthopedic implants was satisfied, which made the alloy a good prospect for biomedical application. The alloy with 70% porosity had the optimum mechanical properties, as well as suitable pore size and porosity, which allowed more bone ingrowth.

[Effectiveness of vacuum sealing drainage combined with anti-taken skin graft for primary closing of open amputation wound].

OBJECTIVE: To observe the effectiveness of vacuum sealing drainage (VSD) combined with anti-taken skin graft on open amputation wound by comparing with direct anti-taken skin graft. METHODS: Between March 2005 and June 2010, 60 cases of amputation wounds for limbs open fractures were selected by using the random single-blind method. The amputation wounds were treated with VSD combined with anti-taken skin graft (test group, n = 30) and direct anti-taken skin graft (control group, n = 30). No significant difference was found in age, gender, injury cause, amputation level, defect size, preoperative albumin index, or injury time between 2 groups (P > 0.05). In test group, the redundant stump skin was used to prepare reattached staggered-meshed middle-thickness skin flap by using a drum dermatome dealing after amputation, which was transplanted amputation wounds, and then the skin surface was covered with VSD for continuous negative pressure drainage for 7-10 days. In control group, wounds were covered by anti-taken thickness skin flap directly after amputation, and conventional dress changing was given. RESULTS: To observe the survival condition of the skin graft in test group, the VSD device was removed at 8 days after operation. The skin graft survival rate, wound infection rate, reamputation rate, times of dressing change, and the hospitalization days in test group were significantly better than those in control group [ 90.0% vs. 63.3%, 3.3% vs. 20.0%, 0 vs. 13.3%, (2.0 +/- 0.5) times vs. (8.0 +/- 1.5) times, and (12.0 +/- 2.6) days vs. (18.0 +/- 3.2) days, respectively] (P < 0.05). The patients were followed up 1-3 years with an average of 2 years. At last follow-up, the scar area and grading, and two-point discrimination of wound in test group were better than those in control group, showing significant differences (P < 0.05). No obvious swelling occurred at the residual limbs in 2 groups. The limb pain incidence and the residual limb length were better in test group than those in control group (P < 0.05). Whereas, no significant difference was found in the shape of the residual limbs between 2 groups (P > 0.05). In comparison with the contralateral limbs, the muscle had disuse atrophy and decreased strength in residual limbs of 2 groups. There was significant difference in the muscle strength between normal and affected limbs (P < 0.05), but no significant difference was found in affected limbs between 2 groups (P > 0.05). CONCLUSION: Compared with direct anti-taken skin graft on amputation wound, the wound could be closed primarily by using the VSD combined with anti-taken skin graft. At the same time it could achieve better wound drainage, reduce infection rate, promote good adhesion of wound, improve skin survival rate, and are beneficial to lower the amputation level, so it is an ideal way to deal with amputation wound in the phase I.