To date, few studies have investigated the feasibility of the loop-mediated isothermal amplification (LAMP) assay for identifying pathogens in tissue samples. This study aimed to investigate the feasibility of LAMP for the rapid detection of methicillin-susceptible or methicillin-resistant Staphylococcus aureus (MSSA or MRSA) in tissue samples, using a bead-beating DNA extraction method. Twenty tissue samples infected with either MSSA (n = 10) or MRSA (n = 10) were obtained from patients who underwent orthopedic surgery for suspected musculoskeletal infection between December 2019 and September 2020. DNA was extracted from the infected tissue samples using the bead-beating method. A multiplex LAMP assay was conducted to identify MSSA and MRSA infections. To recognize the Staphylococcus genus, S. aureus, and methicillin resistance, 3 sets of 6 primers for the 16S ribosomal ribonucleic acid (rRNA) and the femA and mecA genes were used, respectively. The limit of detection and sensitivity (detection rate) of the LAMP assay for diagnosing MSSA and MRSA infection were analyzed. The results of this study suggest that the LAMP assay performed with tissue DNA samples can be a useful diagnostic method for the rapid detection of musculoskeletal infections caused by MSSA and MRSA.
We aimed to investigate whether the anterior superior iliac spine could provide consistent rotational landmark of the tibial component during mobile-bearing medial unicompartmental knee arthroplasty (UKA) using computed tomography (CT). During sagittal tibial resection, we utilized the ASIS as a rotational landmark. In 47 knees that underwent postoperative CT scans after medial UKA, the tibial component position was assessed by drawing a line tangential to the lateral wall of the tibial component. Rotation of the tibial component was measured using two reference lines: a line perpendicular to the posterior cortical rim of the tibia (angle α) and Akagi's line (angle β). Instant bearing position and posterior cruciate ligament fossa involvement were also evaluated. External rotation of the tibial component relative to each reference line and external rotation of the bearing relative to the lateral wall of the tibial component were considered positive values.Purpose
Methods
Spontaneous osteonecrosis of the knee (SONK) is a distinct clinical condition occurring in patients without any associated risk factors. There is controversy as to the best method of treatment, and the available literature would suggest that patients with SONK have a worse outcome. We evaluated the clinical and radiographic outcomes of unicompartmental knee arthroplasty using Oxford prosthesis in patients with spontaneous osteonecrosis Between September 2002 and March 2008, 20 knees (18 patients) with SONK were treated with Oxford unicompartmental knee arthroplasty. There were fifteen women and three men with a mean age of 61.1 years old. The mean follow up was 37 months. The clinical assessment was performed using the American knee society score rating system. The preoperative radiography and MRI were analyzed according to size and stage of the osteonecrotic lesion and the osteoarthritic changes. Postoperatively, new osteonecrotic lesion, loosening of implant, subsidence, arthritic changes of other compartment were recorded. The mean preoperative knee score and the knee function score were 52.5 and 56.0 points, respectively. The knee score was improved to 89.2 points (p <
0.05) and the knee function score was also improved to 85.2 points (p <
0.05) at last follow up. There were no implant failures. There was no new necrotic lesion in the lateral compartment, loosening, subsidence and arthritic change. The Oxford Unicompartmental knee arthroplasty for spontaneous osteonecrosis of the knee provided satisfactory clinical and radiological results in a short to medium term. However, a longer term follow up will be needed.
