A new joint reconstruction technique in the treatment of giant cell tumors around the knee: Structural allograft and unicompartmental arthroplasty.

OBJECTIVE: The long-term prognosis of patients who underwent unicompartmental knee arthroplasty (UKA) with a structural allograft or hemiarticular allograft transplantation to treat giant cell tumors (GCTs) around the knee and the prosthesis survival rate were analyzed. METHODS: We retrospectively reviewed 73 patients who were diagnosed with GCTs around the knee and underwent surgery to restore joint function from 2000 to 2015. Patients were divided into two groups according to the surgical procedure used for functional knee reconstruction: hemiarticular allograft transplantation or structural allograft and UKA. The Knee Society Score (KSS) and Western Ontario and McMaster Universities Arthritis Index (WOMAC) were used to analyze postoperative knee function between the two groups. The Kellgren-Lawrence (K-L) classification system was used to evaluate the progression of osteoarthritis. The incidence of complications and the prosthesis survival rate were also investigated. RESULTS: Patients who underwent UKA to treat GCT demonstrated significantly improved knee function. The rate of an excellent or good KSS was significantly different between the two groups (p = 0.041 at the 1-year follow-up, p = 0.033 at the last follow-up). The proportion of severe cases according to WOMAC in the two groups was also different (p = 0.030 at the 1-year follow-up, p = 0.021 at the last follow-up). According to the K-L grade of unaffected compartments, UKA better prevented the progression of osteoarthritis (p = 0.034). CONCLUSIONS: Patients with GCTs around the knee could benefit from UKA. In addition to providing better knee function and range of motion, UKA could also slow the progression of osteoarthritis in the knee joint. This new surgical method could meet the needs of patients wishing to preserve joint integrity and favorable joint function.

The diagnostic value of blood sample NGS in patients with early periprosthetic joint infection after total hip arthroplasty.

The diagnostic value of next-generation sequencing (NGS) of blood samples from patients with periprosthetic joint infection (PJI) after total hip arthroplasty (THA) was evaluated by comparing it with drainage fluid NGS and bacterial culture. The study was designed as a retrospective diagnostic test. Thirty-six infected patients were diagnosed with PJI according to the Musculoskeletal Infection Society (MSIS) criteria and 57 volunteers were included in our study. NGS and bacterial culture were chosen to detect PJI after THA. Blood samples and drainage fluid were collected for NGS, and the drainage fluid, which was collected at the same time as the NGS drainage fluid sample, was used for bacterial culture. The primary outcomes of interest were sensitivity, specificity, and accuracy. In the infection group, 31 patients showed positive results by blood sample NGS, 33 patients showed positive results by drainage fluid NGS, and 17 patients showed positive bacterial culture results. In the control group, the results of 2 blood sample NGS, 16 drainage fluid NGS, and 3 bacterial cultures were positive. The sensitivity, specificity, and accuracy of the blood sample were 0.86, 0.96, and 0.92, respectively. The sensitivity, specificity, and accuracy of the drainage fluid samples were 0.92, 0.72, and 0.80, respectively. The sensitivity, specificity, and accuracy of bacterial culture were 0.47, 0.95, and 0.79, respectively. The study demonstrated that both the sensitivity and specificity of NGS were higher than those of bacterial culture, regardless of the kind of sample. Compared with drainage fluid NGS, the sensitivity of blood sample NGS was slightly lower (0.86 vs 0.92), but blood sample NGS showed higher specificity (0.96 vs 0.72). In total, the diagnostic value of blood sample NGS was superior to that of drainage fluid NGS and bacterial culture. The majority of infected patients could be identified by blood sample NGS. Moreover, because of its high specificity, blood sample NGS can not only detect infectious bacteria but also distinguish infectious from non-infectious bacteria, which is dramatically different from using drainage fluid NGS.

Differential Soft Sensor-Based Measurement of Interactive Force and Assistive Torque for a Robotic Hip Exoskeleton.

With the emerging of wearable robots, the safety and effectiveness of human-robot physical interaction have attracted extensive attention. Recent studies suggest that online measurement of the interaction force between the robot and the human body is essential to the aspects above in wearable exoskeletons. However, a large proportion of existing wearable exoskeletons monitor and sense the delivered force and torque through an indirect-measure method, in which the torque is estimated by the motor current. Direct force/torque measuring through low-cost and compact wearable sensors remains an open problem. This paper presents a compact soft sensor system for wearable gait assistance exoskeletons. The contact force is converted into a voltage signal by measuring the air pressure within a soft pneumatic chamber. The developed soft force sensor system was implemented on a robotic hip exoskeleton, and the real-time interaction force between the human thigh and the exoskeleton was measured through two differential soft chambers. The delivered torque of the hip exoskeleton was calculated based on a characterization model. Experimental results suggested that the sensor system achieved direct force measurement with an error of 10.3 ± 6.58%, and torque monitoring for a hip exoskeleton which provided an understanding for the importance of direct force/torque measurement for assistive performance. Compared with traditional rigid force sensors, the proposed system has several merits, as it is compact, low-cost, and has good adaptability to the human body due to the soft structure.

Existing hip joint disease is associated with an increased incidence of hip fracture in adults: A retrospective survey of 9710 individuals from a single center.

Objective: In hip disease patients, pain and movement restrictions might cause changes in bone strength and increase the likelihood of falls, finally leading to hip fracture. The aim of this study was to identify the incidence of, characteristics of and risk factors for hip fracture in patients with existing hip disease. Methods: This was a retrospective cohort study. Patients with existing hip disease treated at both outpatient and inpatient departments of our institute were identified by searching the electronic medical record system and followed retrospectively for the occurrence of hip fracture. Demographic and clinical characteristics, such as age, sex and kind of primary hip disease, were collected from the electronic medical record system. The incidence and timing of hip fracture were estimated, and a Cox regression model was built to identify the independent risk factors for hip fracture in these patients. Results: A total of 9710 eligible patients were included. After a mean follow-up of 3.97 years, hip fractures were identified in 95 patients, for an estimated incidence of hip fracture of 978.37 per 100,000 patients. The femoral neck was involved in 49 fractures (51.58 %), and the femoral trochanter was involved in 45 fractures (47.37 %). Four independent risk factors and one protective factor for hip fracture in patients with hip diseases were identified: age (HR = 1.116, 95 % CI = 1.094-1.138), the presence of osteonecrosis of the femoral head (HR = 2.201, 95 % CI = 1.217-3.980), a lower Harris hip score (HR = 0.966, 95 % CI = 0.949-0.982), a history of previous hip surgery (HR = 2.126, 95 % CI = 1.304-3.466) and the use of walking aids (HR = 0.588, 95 % CI = 0.354-0.975). A scoring system with a total score of 20 points was built, which included all of the above risk factors. The predictive scores for a low risk (estimated incidence of hip fracture ≤30 %), a moderate risk (estimated incidence of hip fracture 31 %-69 %), and a high risk (estimated incidence of hip fracture ≥70 %) of hip fracture were ≤8.5 points, 9.0-13.0 points and ≥13.5 points, respectively. Conclusion: The incidence of hip fracture in the special population of patients with existing hip disease was determined. Elderly patients, patients with a history of hip surgery, patients with osteonecrosis and patients with poor Harris hip scores were at increased risk of hip fracture. In patients with a predictive score greater than 9 points, indicating a moderate to high risk of hip fracture, the use of a walking aid might reduce the risk of hip fracture.

Bone Remodelling of the Proximal Femur After Hip Revision with a Metaphyseal-Fixation Femoral Stem Component.

Background: Whether hip revision with a metaphyseal-fixation femoral stem component can restore the bone mass of the proximal femur remains unclear. The aims of this study were to identify whether the bone mineral density (BMD) of the proximal femur increases following hip revision with a metaphyseal-fixation femoral stem and to identify the factors associated with BMD recovery. Methods: This was a retrospective study involving 36 patients who underwent hip arthroplasty with a metaphyseal-diaphyseal fixation stem (standard length stem) and had indications for hip revision, which was performed with a proximal press-fit short-stem prosthesis for each patient. Dual-energy X-ray absorptiometry (DEXA) was used to obtain, evaluate, and compare the BMD at baseline and one year and two years postoperatively. The proximal femur was divided into several independent areas according to the Gruen zone (Gruen 1 to Gruen 7 from the greater trochanter counterclockwise to the lesser trochanter). Logistic regression analyses were used to assess potential factors significantly associated with an increase in BMD. Results: An increased BMD was obviously identified in the proximal femur. Two years after the surgery, the BMD of the Gruen 1, Gruen 2, Gruen 6, and Gruen 7 areas had increased by 22.6%, 12.6%, 16.2% and 24.2%, respectively, relative to baseline. Three independent risk factors associated with bone mineral density recovery were identified: age (OR=1.100, 95% CI=1.005-1.203, P=0.038), osteoporosis (OR=14.921, 95% CI=1.223-182.101, P=0.034) and fair to poor hip function (OR=13.142, 95% CI=1.024-168.582, P=0.048). Conclusion: This study confirms that metaphyseal-fixation stem hip revision can indeed help restore bone mass in the proximal femur, especially in the Gruen 1, Gruen 2, Gruen 6 and Gruen 7 zones. It was also found that advanced age, osteoporosis, and fair to poor hip joint function were three important risk factors affecting the recovery of proximal femur bone mass after surgery. Trial Registration: Retrospectively registered.

First measurements of the radiation dose on the lunar surface.

Human exploration of the Moon is associated with substantial risks to astronauts from space radiation. On the surface of the Moon, this consists of the chronic exposure to galactic cosmic rays and sporadic solar particle events. The interaction of this radiation field with the lunar soil leads to a third component that consists of neutral particles, i.e., neutrons and gamma radiation. The Lunar Lander Neutrons and Dosimetry experiment aboard China's Chang'E 4 lander has made the first ever measurements of the radiation exposure to both charged and neutral particles on the lunar surface. We measured an average total absorbed dose rate in silicon of 13.2 ± 1 µGy/hour and a neutral particle dose rate of 3.1 ± 0.5 µGy/hour.

An analysis of dependency of counting efficiency on worker anatomy for in vivo measurements: whole-body counting.

In vivo radiobioassay is integral to many health physics and radiological protection programs dealing with internal exposures. The Bottle Manikin Absorber (BOMAB) physical phantom has been widely used for whole-body counting calibrations. However, the shape of BOMAB phantoms-a collection of plastic, cylindrical shells which contain no bones or internal organs-does not represent realistic human anatomy. Furthermore, workers who come in contact with radioactive materials have rather different body shape and size. To date, there is a lack of understanding about how the counting efficiency would change when the calibrated counter is applied to a worker with complicated internal organs or tissues. This paper presents a study on various in vivo counting efficiencies obtained from Monte Carlo simulations of two BOMAB phantoms and three tomographic image-based models (VIP-Man, NORMAN and CNMAN) for a scenario involving homogeneous whole-body radioactivity contamination. The results reveal that a phantom's counting efficiency is strongly dependent on the shape and size of a phantom. Contrary to what was expected, it was found that only small differences in efficiency were observed when the density and material composition of all internal organs and tissues of the tomographic phantoms were changed to water. The results of this study indicate that BOMAB phantoms with appropriately adjusted size and shape can be sufficient for whole-body counting calibrations when the internal contamination is homogeneous.

CNMAN: a Chinese adult male voxel phantom constructed from color photographs of a visible anatomical data set.

A voxel phantom of Chinese adult male called CNMAN was constructed from color photographs of the first Chinese visible human data set, for radiation protection purpose. This data set was obtained from a 35-y-old Chinese male cadaver by a medical university in China. The man, 170 cm in height and 65 kg in weight, was dead without any pathological changes. The image size for transversal anatomical photographs of the whole body was 3072 x 2048. After the photographs were semi-automatically segmented, the voxel phantom (CNMAN) with a voxel size of 0.16 mm x 0.16 mm x 1 mm, consisting of 29 tissues or organs was constructed. Combined with the MCNP Monte Carlo transport code, preliminary results for radiation protection dosimetry were obtained based on this Chinese voxel phantom.

Deformable adult human phantoms for radiation protection dosimetry: anthropometric data representing size distributions of adult worker populations and software algorithms.

Computational phantoms representing workers and patients are essential in estimating organ doses from various occupational radiation exposures and medical procedures. Nearly all existing phantoms, however, were purposely designed to match internal and external anatomical features of the Reference Man as defined by the International Commission on Radiological Protection (ICRP). To reduce uncertainty in dose calculations caused by anatomical variations, a new generation of phantoms of varying organ and body sizes is needed. This paper presents detailed anatomical data in tables and graphs that are used to design such size-adjustable phantoms representing a range of adult individuals in terms of the body height, body weight and internal organ volume/mass. Two different sets of information are used to derive the phantom sets: (1) individual internal organ size and volume/mass distribution data derived from the recommendations of the ICRP in Publications 23 and 89 and (2) whole-body height and weight percentile data from the National Health and Nutrition Examination Survey (NHANES 1999-2002). The NHANES height and weight data for 19 year old males and females are used to estimate the distributions of individuals' size, which is unknown, that corresponds to the ICRP organ and tissue distributions. This paper then demonstrates the usage of these anthropometric data in the development of deformable anatomical phantoms. A pair of phantoms--modeled entirely in mesh surfaces--of the adult male and female, RPI-adult male (AM) and RPI-adult female (AF) are used as the base for size-adjustable phantoms. To create percentile-specific phantoms from these two base phantoms, organ surface boundaries are carefully altered according to the tabulated anthropometric data. Software algorithms are developed to automatically match the organ volumes and masses with desired values. Finally, these mesh-based, percentile-specific phantoms are converted into voxel-based phantoms for Monte Carlo radiation transport simulations. This paper also compares absorbed organ doses for the RPI-AM-5th-height and -weight percentile phantom (165 cm in height and 56 kg in weight) and the RPI-AM-95th-height and -weight percentile phantom (188 cm in height and 110 kg in weight) with those for the RPI-AM-50th-height and -weight percentile phantom (176 cm in height and 73 kg in weight) from exposures to 0.5 MeV external photon beams. The results suggest a general finding that the phantoms representing a slimmer and shorter individual male received higher absorbed organ doses because of lesser degree of photon attenuation due to smaller amount of body fat. In particular, doses to the prostate and adrenal in the RPI-AM-5th-height and -weight percentile phantom is about 10% greater than those in the RPI-AM-50th-height and -weight percentile phantom approximating the ICRP Reference Man. On the other hand, the doses to the prostate and adrenal in the RPI-AM-95th-height and -weight percentile phantom are approximately 20% greater than those in the RPI-AM-50th-height and -weight percentile phantom. Although this study only considered the photon radiation of limited energies and irradiation geometries, the potential to improve the organ dose accuracy using the deformable phantom technology is clearly demonstrated.

An ICRP-based Chinese adult male voxel model and its absorbed dose for idealized photon exposures--the skeleton.

A site-specific skeleton voxel model for a Chinese adult male was constructed in this paper upon a previous Chinese individual voxel model. The whole skeleton was divided into 19 site-specific bones and bone groups; the mass of various skeleton tissues at each bone site, e.g. red bone marrow, was specified according to Asian reference data and the distribution data from ICRP Publication 70. The resultant voxel model (called CAM) has a resolution of 1.741 mm x 1.741 mm in plane, and the total bone mass is 8397.8 g which is almost equal to the Asian reference value. Dose coefficients for the red bone marrow and bone surface in CAM were calculated, and then compared with those from Rex, CMP and ICRP 74. It shows that the dose to RBM in Rex is generally 12% lower than that to CAM in low-energy range (30-150 keV) for AP, LAT, ROT and ISO geometries. It is also found that the RBM dose from mathematical models, i.e. CMP and ICRP 74, is underestimated by -30% in AP geometry and overestimated by 30% in PA geometry for low-energy photons. Meanwhile, the bone surface dose in the low-energy range is overestimated by 150% and 75% in CMP and ICRP 74, respectively, if compared with that from CAM.

Organ dose conversion coefficients on an ICRP-based Chinese adult male voxel model from idealized external photons exposures.

A high-resolution whole-body voxel model called CAM representing the Chinese adult male was constructed in this paper based on a previous individual voxel model. There are more than 80 tissues and organs in CAM, including almost all organs required in the ICRP new recommendation. The mass of individual organs has been adjusted to the Chinese reference data. Special considerations were given to representing the gross spatial distribution of various bone constituents as realistically as possible during the construction of the site-specific skeleton. Organ dose conversion coefficients were calculated for six idealized external photon exposures from 10 keV to 10 MeV by using Monte Carlo simulation. The resulting dose coefficients were then compared with those from other models, e.g. CMP, ICRP 74, Rex, HDRK-man and VIP-man. Old and new effective male doses of CAM were calculated by using the tissue weighting factors from ICRP 60 and 103 Publications, respectively. Dosimetric differences between mathematical and voxel models, and the differences between Asian and Caucasian models are also discussed in this paper.