Biodegradable iron alloy implants have become one of the most ideal possible candidates because of their biocompatibility and comprehensive mechanical properties. Iron alloy’s impact on chondrocytes is still unknown, though. This investigation looked at the biocompatibility and degradation of the Fe30Mn0.6N alloy as well as how it affected bone formation and chondrocyte autophagy. In vivo implantation of Fe30Mn0.6N and Ti6Al4V rods into rabbit femoral cartilage and femoral shaft was carried out to evaluate the degradation of the alloy and the cartilage and bone response at different intervals. After 8 weeks of implantation, the cross-sectional area of the Fe30Mn0.6N alloys lowered by 50.79 ± 9.59 % . More Ca and P element deposition was found on the surface Fe30Mn0.6N rods by using energy dispersive spectroscopy (EDS) and scanning electron microscopy ( P < 0.05 ). After 2, 4, and 8 weeks of implantation, no evident inflammatory infiltration was seen in peri-implant cartilage and bone tissue of Fe30Mn0.6N and Ti6Al4V alloys. Also, implantation of Fe30Mn0.6N alloy promoted autophagy in cartilage by detecting expression of LC3-II compared with Ti6Al4V after implantation ( P < 0.05 ). Fe30Mn0.6N alloy also stimulated early osteogenesis at the peri-implant interface compared with Ti6Al4V after implantation ( P < 0.05 ). In the in vitro test, we found that low concentrations of Fe30Mn0.6N extracts had no influence on cell viability. 15% and 30% extracts of Fe30Mn0.6N could upregulate autophagy compared to the control group by detecting beclin-1, LC3, Atg3, and P62 on the basis of WB and IHC ( P < 0.05 ). Also, the PI3K-AKT-mTOR signaling pathway mediated in the upregulation of autophagy of chondrocytes resulting in exposure to extract of Fe30Mn0.6N alloy. It is concluded that Fe30Mn0.6N showed degradability and biocompatibility in vivo and upregulated autophagy activity in chondrocytes.

ObjectiveThe high hip center (HHC) technique has been proposed for the treatment of patients with developmental dysplaisa of the hip (DDH) who have an acetabular bone defect. However, the importance of global femoral offset (FO) in the application of this technique has not been sufficiently appreciated. Our goals were to confirm that the HHC technique is feasible in the treatment of patients with DDH and to assess the function of global FO in this procedure.MethodsWe retrospectively analyzed 73 patients who underwent total hip arthroplasty using high hip center technique for unilateral DDH at our hospital between January 2014 and June 2019. According to global FO, the patients were split into three groups: increased FO group (increment greater than 5 mm), restored FO group (restoration within 5 mm) and decreased FO group (reduction greater than 5 mm). Patients' medical records and plain radiographs were reviewed. One‐way ANOVA was used to compare radiographic outcomes and Harris hip score (HHS). Paired t‐test was used to assess preoperative and postoperative HHS and leg length discrepancy. Trochanteric pain syndrome, Trendelenburg sign and postoperative limp was evaluated with Fisher's exact test.ResultsThe average follow‐up time was 7.5 ± 1.4 years. The patients' HHS and leg length discrepancy were significantly improved (p < 0.05). In terms of vertical acetabular height, abductor arm, postoperative leg length difference, and acetabular cup inclination, there was no statistically significant difference between the three groups. At the last follow‐up, HHS was significantly higher in the restored FO group than in the decreased FO and increased FO groups. Trochanteric pain syndrome occurred in 15.0% and Trendelenburg sign and postoperative limp in 8.2% of all patients, respectively. Trochanteric pain syndrome, Trendelenburg sign and postoperative limp did not differ significantly across the three groups. One patient in increased FO group underwent revision for dislocation 6 years after surgery.ConclusionThe HHC technique is an alternative technique for total hip arthroplasty in patients with acetabular bone abnormalities, according to the results of the mid‐term follow‐up. Also, controlling the correction of the global femoral offset to within 5 mm may lead to better clinical outcomes.

Ferroalloy has shown potential as implant materials, but little attention has been paid to their effects on synovial tissue ferroptosis. This study aimed to examine the mechanical properties, degradability and biocompatibility of Fe-30Mn-0.6N alloy and effects of it on synovial tissue ferroptosis. Tensile testing showed that Fe-30Mn-0.6N alloys exhibited tensile strength of 487 ± 18 MPa, yield strength of 221 ± 10 MPa, elongation of 16.9 ± 0.3% and Young's modulus of 37.7 ± 1.3 GPa.In vivo experiments, the cross-sectional area of the Fe-30Mn-0.6N alloys decreased by 73.32 ± 12.73% after 8 weeks of implantation. The results of scanning electron microscopy (SEM) and surface elemental analysis (EDS) showed that the Fe-30Mn-0.6N alloys had more Ca, O, C and P element deposition (p < .05). After 2, 4 and 8 weeks of implantation, no inflammatory response was observed in peri-implant synovial tissue of Fe-30Mn-0.6N and Ti-6Al-4V alloys, and Fe-30Mn-0.6N alloys did not affect the expression of the ferroptosis inhibitory gene Glutathione peroxidase 4 (GPX4). Compared with the control group, 30% Fe-30Mn-0.6N alloy extracts did not affect the cell viability (p > .05) in vitro, and intracellular Fe 2+ and the reactive oxygen species (ROS) was significantly reduced (p < .05). WB and PCR results showed that the 30% extracts increased the protein activity and mRNA expression of GPX4, FTH1 and SLC7A11 in synoviocytes, but had no effect on PTGS2 and p53. It is concluded that Fe-30Mn-0.6N had degradability and biocompatibility in periimplant synovial tissue, and did not induce significantly ferroptosis in synoviocytes.biodegradable alloy, Fe-Mn alloy, ferroptosis, glutathione peroxidase 4, synoviocytes | INTRODUCTIONRecently, the development of orthopedic implant materials has attracted widespread attention. Titanium, titanium alloys, stainless steel, and cobalt-based alloys are common implant materials. However, these materials produce stress shielding due to their higher Young's modulus, which is higher than human bone density . Studies have shown that bone resorption caused by stress shielding is one of the reasons for the induction of glenoid loosening in total shoulder arthroplasty. 1 Interim follow-up of the low elastic modulus femoral stem showed that no patients had prosthesis loosening, and mild stress shielding was observed in 65% of patients. 2In addition, metal particles and ions from corrosion and wear of implants are released into local tissues and blood, which can have a range of adverse effects on patients. 3 As an alloy with high Tianyu Yang and Shimin Hao equally contributed to this work.Hao Lei Guo and Tianlong Jiang equally contributed to this work.