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Abstract Background Opening wedge high tibial osteotomy (OWHTO) is an effective surgical treatment for knee osteoarthritis. This study aimed to explore the feasibility and accuracy of a novel 3D-printed patient-specific instrument (PSI) based on “H-point” for medial OWHTO in a prospective cadaver study. Methods Twenty-six fresh-frozen lower limbs were collected and randomly divided into two groups: PSI group treated with 3D virtual preoperative planning and a novel 3D-printed PSI; control group with the standard technique. 3D models were reversely reconstructed for preoperative surgical planning, guide plate design, and simulated osteotomy. Anatomic features of “H-point,” surgical time, fluoroscopic dose, correction accuracy including tibiofemoral angle (FTA) and posterior tibial slope (TS) angle were measured. Results First, H-point was always described as a bony bulge in the posteromedial to the proximal tibia and had a relatively constant relationship with the osteotomy site. Second, the absolute correction error of mFTA and TS were significantly smaller in the PSI group. The effective rate of TS in the PSI group was more concentrated with absolute correction error within 1° and within 2° for 53.3% and 93.3%, compared to 9.1% and 45.5% in the control group. The total operation time, positioning osteotomy time, distraction correction time and fluoroscopy dose in the PSI group were significantly less than those in the control group. Conclusions The novel 3D-printed PSI based on H-point is feasibility and accuracy with advantages in terms of TS, surgery time and radiation dose for OWHTO.

The fluorescence spectra of protoporphyrin IX (PPIX) solutions and human serum samples were measured and analyzed under physiological conditions. The experimental results showed that the fluorescence of PPIX in human serum was mainly derived from PPIX-serum albumin complex. Moreover, the effects of serum albumin and PPIX on the PPIX emission fluorescence were also investigated. Compared with pure PPIX solution, not only a red-shift of PPIX fluorescence peak was found for PPIX+albumin solution, but also albumin had a fluorescence enhancement effect on protoporphyrin IX. For the mixture of PPIX+albumin, with the increase of PPIX the wavelength of the PPIX emission peak will increased a little when its concentration was less than 0.8 x 10(-5) mol x L(-1), but was nearly invariable when its concentration was more than 0.8 x 10(-5) mol x L(-1).

A method was developed for the determination of As, Pb, Sn, Sb and Bi in high temperature iron and nickel-based alloy by graphite furnace atomic absorption spectrometry combined with liquid-liquid extraction. These elements formed complexes with I- ions and were subsequently extracted into MIBK to be separated from matrix elements. The effects of remnant matrix elements were studied in detail. Meanwhile, the interferences of other elements, such as W, Nb and Ta, were eliminated with masking method. The recovery rates for As, Pb, Sn, Sb and Bi are in the range of 93%-99%, and the relative standard deviations are from 8.8% to 12%.

Determination of trace element arsenic in high purity nickel by GFAAS in STPF conditions is described in this paper. The dry time, ashing temperature and atomization temperature are obtained by optimization process. The standard solutions are matched to eliminate the influences of matrix nickel, and nickel is also as the chemical matrix modifier in the detected. The characteristic mass of the method is 1.9 pg, the average relative standard deviation is 1.4%, the recovery rate is in the range of 95%-103%.