Iliopsoas fibrosis after revision of total hip arthroplasty revealed by 68Ga-FAPI PET/CT: a case report.

Background: Total hip arthroplasty (THA) is a well-established surgical procedure that has been extensively validated to alleviate pain, enhance joint function, improve the ability to perform daily activities, and enhance overall quality of life. However, this procedure is associated with certain complications, among which skeletal muscle fibrosis is a frequently overlooked but significant complication that can lead to persistent pain. Currently, there is no effective method for diagnosing skeletal muscle fibrosis following total hip arthroplasty. Case report: We report a 75-year-old male patient who complained of left groin pain after revision total hip arthroplasty. Serological examinations, X-rays, and bone scan results were all normal. However, during the 68Ga-FAPI PET/CT examination, we observed significant radiotracer uptake along the iliopsoas muscle. This abnormal uptake pattern suggested potential biological activity in this specific area. Combined with physical examination, the patient was diagnosed with iliopsoas fibrosis. Conclusions: The presented images indicated that the uptake pattern was an important indicator for diagnosis, and the prospect of fibroblast activation protein in the diagnosis of skeletal muscle fibrosis has shown certain application value.

Association of Use of Tourniquets During Total Knee Arthroplasty in the Elderly Patients With Post-operative Pain and Return to Function.

Objective: During total knee arthroplasty (TKA), tourniquet may negatively impact post-operative functional recovery. This study aimed at investigating the effects of tourniquet on pain and return to function. Methods: Pubmed, Embase, and Cochrane Library were comprehensively searched for randomized controlled trials (RCTs) published up to February 15th, 2020. Search terms included; total knee arthroplasty, tourniquet, and randomized controlled trial. RCTs evaluating the efficacies of tourniquet during and after operation were selected. Two reviewers independently extracted the data. Effect estimates with 95% CIs were pooled using the random-effects model. Dichotomous data were calculated as relative risks (RR) with 95% confidence intervals (CI). Mean differences (MD) with 95% CI were used to measure the impact of consecutive results. Primary outcomes were the range of motion (ROM) and visual analog scale (VAS) pain scores. Results: Thirty-three RCTs involving a total of 2,393 patients were included in this study. The mean age is 65.58 years old. Compared to no tourniquet group, the use of a tourniquet resulted in suppressed ROM on the 3rd post-operative day [MD, -4.67; (95% CI, -8.00 to -1.35)] and the 1st post-operative month [MD, -3.18; (95% CI, -5.92 to -0.44)]. Pain increased significantly when using tourniquets on the third day after surgery [MD, 0.39; (95% CI, -0.19 to 0.59)]. Moreover, tourniquets can reduce intra-operative blood loss [MD, -127.67; (95% CI, -186.83 to -68.50)], shorter operation time [MD, -3.73; (95% CI, -5.98 to -1.48)], lower transfusion rate [RR, 0.85; (95% CI, 0.73-1.00)], higher superficial wound infection rates RR, 2.43; [(5% CI, 1.04-5.67)] and higher all complication rates [RR, 1.98; (95% CI, 1.22-3.22)]. Conclusion: Moderate certainty evidence shows that the use of a tourniquet was associated with an increased risk of higher superficial wound infection rates and all complication rates. Therefore, the findings did not support the routine use of a tourniquet during TKA.

Field-free switching of perpendicular magnetization through spin-orbit torque in FePt/[TiN/NiFe]5 multilayers.

In order to maintain the thermal stability of SOT devices with nanoscale size, it is desirable to achieve current induced magnetic switching in magnetic materials with high perpendicular anisotropy. In the present paper, current induced field-free switching of FePt/[TiN/NiFe]5 is achieved by interlayer exchange coupling, in which in-plane magnetized NiFe serves as a coupling layer through a TiN space layer. The large Ku (1.03 × 107 erg cc-1) and low critical current density values (0.17 × 107 A cm-2) show great advantages in thermal stability and energy consumption. Interestingly, it is found that the rotation directions of the current-induced magnetic switching loops under different applied magnetic fields are dependent on the sputtering temperature of [TiN/NiFe]5 multilayers: once sign change for FePt/[TiN/NiFe]5 RT and three sign changes for FePt/[TiN/NiFe]5 HT. Simultaneously, when the magnetization direction of NiFe changes from the Hx direction to -Hx direction, the switching polarities at Hx = 0 always remain unchanged, which is different from other groups' reports. These phenomena may be attributed to the combined effect of TiN layer thickness induced ferromagnetic or antiferromagnetic coupling and the inherent Hin. Furthermore, gradual tuning of resistance states through the trains of current pulses has also been realized, showing potential applications in artificial synaptic networks. These results will put forward the applications of L10-FePt in current controlled MRAM and neuromorphic computing.

A Seismic Data Acquisition System Based on Wireless Network Transmission.

A seismic data acquisition system based on wireless network transmission is designed to improve the low-frequency response and low sensitivity of the existing acquisition system. The system comprises of a piezoelectric transducer, a high-resolution data acquisition system, and a wireless communication module. A seismic piezoelectric transducer based on a piezoelectric simply supported beam using PMN-PT is proposed. High sensitivity is obtained by using a new piezoelectric material PMN-PT, and a simply supported beam matching with the PMN-PT wafer is designed, which can provide a good low-frequency response. The data acquisition system includes an electronic circuit for charge conversion, filtering, and amplification, an FPGA, and a 24-bit analog-to-digital converter (ADC). The wireless communication was based on the ZigBee modules and the WiFi modules. The experimental results show that the application of the piezoelectric simply supported beam based on PMN-PT can effectively improve the sensitivity of the piezoelectric accelerometer by more than 190%, compared with the traditional PZT material. At low frequencies, the fidelity of the PMN-PT piezoelectric simply supported beam is better than that of a traditional central compressed model, which is an effective expansion of the bandwidth to the low-frequency region. The charge conversion, filtering, amplification, and digitization of the output signal of the piezoelectric transducer are processed and, finally, are wirelessly transmitted to the monitoring centre, achieving the design of a seismic data acquisition system based on wireless transmission.

Investigation of the Resistive Switching Mechanisms and Rectification Characteristics of HfO2-Based Resistive Random Access Memory Devices with Different Electrode Materials.

To study the substitutability of noble metal electrodes in memristors, the effect of Pt/HfO2/Ti structure on the replacement of noble metal electrode Pt by different electrodes was studied. Compared with the unsubstituted devices, the HfO2-based RRAM devices with TiN and TiOxNy electrodes devices showed good resistive switching performance and resistive switching mechanism under oxygen ion migration. Five devices were prepared, and their resistive switching mechanism under oxygen ion migration was investigated. Moreover, besides the resistive switching phenomenon of these RRAM devices, it was found that significant rectifying characteristics were exhibited in a highresistance state (HRS). This phenomenon can be explained by regulation of the Schottky barrier of the interface between the top electrode and the resistive layer, which can be influenced by the migration of oxygen vacancies.

Noise Modeling and Simulation of Giant Magnetic Impedance (GMI) Magnetic Sensor.

The detection resolution of a giant magneto-impedance (GMI) sensor is mainly limited by its equivalent input magnetic noise. The noise characteristics of a GMI sensor are evaluated by noise modeling and simulation, which can further optimize the circuit design. This paper first analyzes the noise source of the GMI sensor. It discusses the noise model of the circuit, the output sensitivity model and the modeling process of equivalent input magnetic noise. The noise characteristics of three modules that have the greatest impact on the output noise are then simulated. Finally, the simulation results are verified by experiments. By comparing the simulated noise spectrum curve and the experimental noise spectrum curve, it is demonstrated that the preamplifier and the multiplier contribute the most to the output white noise, and the low-pass filter plays a major role in the output 1/f noise. These modules should be given priority in the optimization of the noise of the conditioning circuit. The above results provide technical support for the practical application of low-noise GMI magnetometers.

Theoretical Analysis of a Microring Resonator Array with High Sensitivity and Large Dynamic Range Based on a Multi-Scale Technique.

By using a multi-scale measurement technique, a high-sensitivity and large dynamic-range sensor array, which consisted of a single resonator and a series of cascaded resonators with a sensing ring and a reference ring, was modeled, and its transmission properties were investigated theoretically and numerically. We also set forth the principle of a multi-scale measurement technique based on the transmission spectrum of a resonator. This sensor array could have a nearly tenfold increase in sensitivity, and an improved dynamic range in an arrow wavelength range. The simulated results were in good agreement with the theoretical analysis.

[Clinical research of debridement with prosthesis retention for periprosthetic joint infection after arthroplasty].

Objective: To investigate the mid-term effectiveness of debridement with prosthesis retention for periprosthetic joint infection (PJI) after total hip arthroplasty (THA) and total knee arthroplasty (TKA), and analyze the influence factors that affected the effectiveness. Methods: A clinical data of 45 cases with PJI after THA (16 cases) and TKA (29 cases) that were treated with debridement with prosthesis retention between January 2011 and January 2015 were collected and analyzed. There were 19 males and 26 females with a mean age of 58.4 years (range, 23-78 years). PJI occurred after primary joint arthroplasty in 40 cases and after revision in 5 cases. The mean time interval between the performance of infection symptoms and the arthroplasty or revision was 15.5 months (range, 0.5-72.0 months). The time interval between the performance of infection symptoms and debridment was 35 days (range, 3-270 days). There were early postoperative infections in 13 cases, acute hematogenous infections in 24 cases, and late chronic infections in 8 cases. X-ray films showed that the location of prosthesis was good. The results of bacilli culture showed that 28 cases were positive and 17 were negative. Twelve cases had sinuses. Length of stay, Hospital for Special Surgery (HSS) score, and Harris score were recorded to evaluate risk factors by using a multivariate logistic regression. Results: The mean length of stay was 22.6 days (range, 5-79 days). All patients were followed up 24-74 months (mean, 52 months). There were 33 cases that retained the prosthesis without further evidence of infection with the success rate was 73.3%. There were significant differences in Harris score and HSS score between pre- and post-operation ( P<0.05). The univariate analysis results showed that the failure of debridement with prosthesis retention had a significant correlation with sinus developing and duration of infection symptoms more than 14 days ( P<0.05). Multivariate logistic regression analysis results showed that sinus developing was an independent risk factor of failure ( P<0.05). Conclusion: Debridement with prosthesis retention plays an important role in treating PJI after THA and TKA. These patients with sinus performing and duration of infection symptoms more than 14 days have higher risk to develop infection again.

Control of Microstructure and Magnetic Properties of FePt Thin Films with TiN-MgO Intermediate Layer.

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.

Using maximum spectrum of continuous wavelet transform for demodulation of an overlapped spectrum in a fiber Bragg grating sensor network.

The maximum spectrum of the continuous wavelet transform (MSCWT) is proposed to demodulate the central wavelengths for the overlapped spectrum in a serial fiber Bragg grating (FBG) sensing system. We describe the operation principle of the MSCWT method. Moreover, the influence of the interval gap between two FBG wavelengths, 3 dB bandwidths, and optical powers of the reflected spectra are discussed. The simulation and experimental results indicate that the MSCWT can resolve an overlapped spectrum and decode the central wavelength with high accuracy. More importantly, the proposed peak detection method can enhance the sensing capacity of a wavelength division multiplexing FBG sensor network.

[COMPARISON OF CEMENTLESS TOTAL HIP ARTHROPLASTY BETWEEN WITH AND WITHOUT SUBTROCHANTERIC FEMORAL SHORTENING OSTEOTOMY IN Crowe TYPE IV DEVELOPMENTAL DYSPLASIA OF HIP].

OBJECTIVE: To investigate the clinical characteristic differences of cementless total hip arthroplasty (THA) between with and without subtrochanteric femoral shortening osteostomy in Crowe type IV developmental dysplasia of the hip (DDH). METHODS: Between January 2006 and March 2012, 21 patients (21 hips) with Crowe type IV DDH who underwent primary THA were enrolled according to inclusion criteria. According to whether subtrochanteric femoral shortening osteostomy was performed during THA or not, the patients were divided into 2 groups: THA with osteostomy group (n = 9) and THA without osteotomy group (n = 12). There was no significant difference in gender, age, body mass index, and hip Harris score between 2 groups (P > 0.05) except leg length discrepancy (t = -3.170, P = 0.005). The operation time, blood loss, postoperative drainage, complications, and radiography data were compared to evaluate the clinical characteristics. RESULTS: The operation time, blood loss, and postoperative drainage of osteotomy group were all significantly greater than those of no osteotomy group (P < 0.05). All patients achieved primary healing of incision; 1 patient (1 hip) had transient sciatic nerve symptom in osteotomy group. The average follow-up time was 53 months (range, 28-88 months). The X-ray films showed good fracture healing at 3-6 months after operation in osteostomy group. No prosthetic loosening or dislocation was found. The hip Harris score was 90.67 ± 4.06 in osteostomy group and 92.17 ± 3.27 in no osteostomy group, showing no significant difference between 2 groups (t = -0.938, P = 0.360). The leg length discrepancy was (0.22 ± 0.26) cm in osteostomy group and (0.18 ± 0.27) cm in no osteostomy group, showing no significant.difference (t = 107.000, P = 0.546). The leg length discrepancy was found in 6 patients of osteotomy group and 5 patients of no osteotomy group. One patient complained of thigh pain in osteotomy group; 2 patients had slight limp (Trendelenburg +) in no osteotomy group. CONCLUSION: THA can improve joint function and increase limb length in the treatment of Crowe type IV DDH. Subtrochanteric shortening osteotomy is an effective treatment which can be performed according to preoperative template measurement, leg length shortening, and the soft tissue tension.

[Application of modular cementless femoral stems in complex revision hip arthroplasty].

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.