RESUMO
The effects of TiN-MgO intermediate layer on the microstructure and magnetic properties of FePt-SiNx-C films were investigated. With doping MgO into TiN, three components were formed, including titanium dioxide, titanium nitride and titanium oxynitride. This caused the decrease of the surface energy and the increase of the interface energy, and further induced the promotion of island growth of FePt, thus the improvement of the isolation and the decrease of FePt grains. On the other hand, the decrease of surface energy and the forming of some titanium dioxide with doping MgO would accompany the deterioration of epitaxial growth and thus the deterioration of the perpendicular magnetic anisotropy of FePt films in a certain degree. By optimizing the concentration of TiN and MgO, the FePt-SiNx-C films with small grain size of 5.86±1.03 nm and good perpendicular anisotropy would be obtained.
RESUMO
OBJECTIVE: To investigate and clarify the key surgical techniques and evaluate clinical effectiveness of modular cementless femoral stems(LINK MP modular stem) in complex revision hip arthroplasty. METHODS: From January 2002 to December 2013, 470 patients in Chinese PLA General Hospital received revision hip arthroplasties using MP stems. Among them, 246 patients were followed for an average of 5.7 years (ranged, 0.5 to 11 years). There were 148 males and 98 females, with an average age of 62.5 years old (ranged from 26 to 83 years old). The most common reason for revision was aseptic loosening of femoral stems (107 cases, 43.5%), followed by prosthetic joint infection (104 cases, 42.3%). Other reasons included unexplained hip or thigh pain, periprosthetic femoral fracture, prosthesis wear and dislocation. According to Paprosky classification of femoral deficiency, there were 171 cases of type IIIA (69.5%), 14 cases of type I, 39 cases of type II, and 22 cases of type IIIB. The average preoperative Harris hip score (HHS) was 37.4 ± 7.5. In addition, radiographic presentation, degree of patients' subjective satisfaction, and clinical effectiveness were assessed as well. RESULTS: The average Harris score was im- proved to 87.8 ± 4.2 after operation,with significant statistical difference when compared to preoperative score (t = 92.13,P = 0.00). Analysis of patients' subjective satisfaction for leg length discrepancy, stability and overall degree of satisfaction showed that the number of patients with great satisfaction were 27, 60, 61 respectively. The most common complication was the periprosthetic fracture (intraoperatively 21 cases and postoperatively 8 cases). Other complications included infection (7 cases), dislocation (5 cases), numbness possibly caused by incomplete sciatic nerve injury (6 cases) and thigh swelling (3 cases). The X-ray taken at the final follow-up revealed that prosthesis subsidence occurred in 4 cases, 2 of which needed a second revision. CONCLUSION: The application of modular cementless femoral stems (LINK MP modular stem) in complex revision hip arthroplasty (especially in cases with the serious defect of proximal femoral bone) shows good results at both the short-term and long-term follow-up, especially in the revision for prosthetic infection with the high success rate. In order to avoid complications and improve clinical outcomes,the surgeons should carefully select proper surgery candidates,perform the procedure with care, and master the key surgical techniques.