It is known that the gait dynamics of elderly substantially differs from that of young people. However, it has not been well studied how this age-related gait dynamics affects the knee biomechanics, e.g., cartilage mechanical response. In this study, we investigated how aging affects knee biomechanics in a female population using subject-specific computational models. Two female subjects (ages of 23 and 69) with no musculoskeletal disorders were recruited. Korea National Institute for Bioethics Policy Review Board approved the study. Participants walked at a self-selected speed (SWS), 110% of SWS, and 120% of SWS on 10 m flat ground. Three-dimensional marker trajectories and ground reaction forces (Motion Analysis, USA), and lower limbs’ muscle activities were measured (EMG, Noraxon USA). Knee cartilage and menisci geometries were obtained from subjects’ magnetic resonance images (3T, GE Health Care). An EMG-assisted musculoskeletal finite element modeling workflow was used to estimate knee cartilage tissue mechanics in walking trials. Knee cartilage and menisci were modeled using a transversely isotropic poroviscoelastic material model. Walking speed in SWS, 110%, and 120% of SWS were 1.38 m/s, 1.51 m/s, and 1.65 m/s for the young, and 1.21 m/s, 1.34 m/s and 1.46 m/s for the elderly, respectively. The maximum tensile stress in the elderly tibial cartilage was ~25%, ~33%, and ~32% lower than the young at SWS, 110%, and 120% of SWS, respectively. These preliminary results suggest that the cartilage in the elderly may not have enough stimulation even at 20% increases in walking speed, which may be one reason for tissue degeneration. To enhance these findings, further study with more subjects and different genders will investigate how age-related gait dynamics affects knee biomechanics.
Joint arthroplasties may be associated with a blood loss, which necessitates transfusion. Especially, hip arthroplasties are highly associate with transfusion to compensate perioperative bleeding. Orthopaedic surgeons and patients have increasing concerns regarding complications of blood transfusions. Although various methods to reduce transfusions have been attempted in TJA, a high percentage of patients require a transfusion during and after the procedures. The purposes of this study were to evaluate the trends of the transfusion(transfusion rates, transfusion amounts, economic burden) in hip arthroplasties, using nationwide data from the National Health Insurance Service (NHIS). We used data from nationwide claims database of Health Insurance Review Assessment Service (HIRA). The data managed by the NHIS were used to identify the 161,934 hip arthroplasties by 3 categories including bipolar hemiarthroplasty(BH), total hip arthroplasty(THA), and revision arthroplasty(RA) from 2007 to 2015. These 3 categories were classified using the operation code recorded in the requisition data of NHIS. The transfusion rates, transfusion amounts, proportion of transfusion, cost of each type of operation was investigated and stratified by age, gender, hospital type, and area in hip arthroplasties. The proportion of transfusion about whole blood, red blood cell, fresh frozen plasma, platelet, was also evaluated in hip arthroplasties.Aims
Patients and methods
We evaluated the accuracy of augmented reality (AR)-based navigation assistance through simulation of bone tumours in a pig femur model. We developed an AR-based navigation system for bone tumour resection, which could be used on a tablet PC. To simulate a bone tumour in the pig femur, a cortical window was made in the diaphysis and bone cement was inserted. A total of 133 pig femurs were used and tumour resection was simulated with AR-assisted resection (164 resection in 82 femurs, half by an orthropaedic oncology expert and half by an orthopaedic resident) and resection with the conventional method (82 resection in 41 femurs). In the conventional group, resection was performed after measuring the distance from the edge of the condyle to the expected resection margin with a ruler as per routine clinical practice.Objectives
Methods
We hypothesised that the synovial white blood cell (WBC) count
in patients with a late periprosthetic joint infection (PJI) of
the hip would depend on the duration of a patient’s symptoms, and
that the optimal diagnostic threshold would also depend on this
period of time. The synovial WBC count and percentage of polymorphonuclear cells
(%PMN), and the serum CRP and ESR levels obtained >
six weeks after
primary THA were compared between 50 infected and 88 non-infected
THAs, and in patients with symptoms for more than or less than two
weeks. Diagnostic thresholds for the synovial WBC count were calculated
using area under the curve calculation.Aims
Patients and Methods
Arthroplasties of hip and knee are associated with blood loss, which may lead to adverse patient outcome. Jehovah's Witnesses do not accept blood transfusion. Performing arthroplasties in Witness patients without transfusion has been a matter of concern. We developed a protocol, which avoids transfusion in arthroplasties of Witness patients, and evaluated the feasibility and safety of the protocol. Our protocol consisted of subcutaneous administration of 4000 U recombinant erythropoietin and 100 mg of intravenous iron supplements when patient's hemoglobin level was less than 10 g/dL in preoperative evaluation. During the operation, cell saver, and plasma expander were used. Postoperatively, recombinant erythropoietin was administered three times a week and iron supplements were administered daily until the hemoglobin level reached 10 g/dL. We evaluated the feasibility of our protocol, perioperative complications and hematologic changes.Introduction
Materials and Methods
Lengthening of the humerus is now an established
technique. We compared the complications of humeral lengthening
with those of femoral lengthening and investigated whether or not
the callus formation in the humerus proceeds at a higher rate than
that in the femur. A total of 24 humeral and 24 femoral lengthenings
were performed on 12 patients with achondroplasia. We measured the
pixel value ratio (PVR) of the lengthened area on radiographs and
each radiograph was analysed for the shape, type and density of
the callus. The quality of life (QOL) of the patients after humeral
lengthening was compared with that prior to surgery. The complication
rate per segment of humerus and femur was 0.87% and 1.37%, respectively.
In the humerus the PVR was significantly higher than that of the
femur. Lower limbs were associated with an increased incidence of
concave, lateral and central callus shapes. Humeral lengthening
had a lower complication rate than lower-limb lengthening, and QOL
increased significantly after humeral lengthening. Callus formation
in the humerus during the distraction period proceeded at a significantly
higher rate than that in the femur. These findings indicate that humeral lengthening has an important
role in the management of patients with achondroplasia.
