Are C-reactive protein (CRP) and neutrophil to lymphocyte ratio (NLR) predictive markers of successful two-stage prosthetic joint infection management?

The treatment of prosthetic joint infections (PJI) regularly involves a two-stage surgical strategy. The second stage is generally performed when the surgeon estimates that the infection is under control based on either the treatment length or clinical and biological data. We have raised the question whether standardization of C-reactive protein (CRP) and neutrophil to lymphocyte ratio (NLR) values could be either indicative of infection control or predictive of infection recurrence. This was an analytical retrospective and monocentric cross-sectional observational study. The CRP and NLR values were recorded prior to the second-stage surgery in a sample of 100 patients who underwent a two-stage revision arthroplasty following a PJI, and these values were correlated with the absence of infectious recurrence within a 2-year follow-up. The statistical analysis consisted of evaluating the diagnostic validity of each marker, first individually, and then in combination. CRP was shown associated with a 68% sensitivity, 40% specificity, 27% positive predictive value (PPV), and 79% negative predictive value (NPV). The ROC curve was 51.1%. The NLR displayed a 12% sensitivity, 89% specificity, 27% PPV, and 75% NPV. The ROC curve was 47.9%. The combination of the two markers did not fundamentally improve the statistical results, with only a 43% concordance of the two markers, 27% sensitivity, 84% specificity, 37% PPV, and 77% NPV. Measuring CRP and NLR values, either individually or in combination, before the second-stage revision arthroplasty did not turn out to be predictive of either infection recurrence or cure within two years of follow-up. Therefore, an absolute test is still lacking, which would enable us to predict without failure the absence of control or the control of a PJI before or after second-stage revision. Level of evidence: Level III, retrospective cross-sectional study.

Unilateral versus simultaneous bilateral total hip arthroplasty. The Belgian experience.

Bilateral hip osteoarthritis is frequent. The safety and patient selection for simultaneous bilateral total hip arthroplasty (SBTHA) are still debated. The purpose of this article is to share our experience and assess if performing SBTHA carries more risk than unilateral total hip arthroplasty (UTHA). METHODS: A retrospective data analysis was performed on 468 patients who underwent either UTHA (418 patients) or SBTHA (50 patients) using a direct anterior approach between June 2016 and December 2020. Apart from SBTHA patients being significantly younger, there was no significant preoperative difference in demographics, comorbidities, surgical variables and biological values between the two groups. Primary outcomes were 90-days emergency room (ER) visit and readmission, as well as 90-days minor and major complications. Secondary outcomes were length of stay (LOS), operative time and blood loss. RESULTS: 90-days ER visit (p=0.244), 90- days readmission (p=0.091), overall complications rate (p=0.376), minor complications (p=0.952) and major complications (p=0.258) were not statistically different between the two groups. Operative time and average LOS were significantly longer in the SBTHA group (p<0.001). Blood loss was significantly higher (p<0.001) in the SBTHA group. However, no difference in the transfusion rate between the two groups was observed (p=0.724). CONCLUSION: Complication rate, 90- days hospital readmission and 90-days ER visit were similar between the two groups. This study shows that performing SBTHA is a safe, effective, and doesn't carry additional risks for patients with bilateral symptomatic osteoarthritis.

Neutrophil-to-lymphocyte ratio (NLR) distribution shows an advantage compared to C-reactive protein (CRP) for the early inflammation monitoring after total hip arthroplasty.

C-reactive protein (CRP) distribution has been used to monitor early inflammation after total hip arthroplasty (THA). Neutrophil to lymphocyte ratio (NLR) is a new and cheap inflammatory marker. This study aimed to verify whether Neutrophil to lymphocyte ratio (NLR) distribution has an advantage when compared to C-reactive protein (CRP) distribution for the inflammation monitoring after total hip arthroplasty (THA). 116 THA patients were retrospectively selected over a 2 years period. They all had available blood tests preoperatively and at postoperative days 2, 4 and 42. Median peak values were compared between CRP and NLR. The effect of demographics on CRP and NLR was tested. At days 4 and 42, 100% and 16.3% of patients had not reached normal CRP (< 10mg/L) while 56.8% and 6.8% of patients had not reached normal NLR (<5) respectively. There was no effect of demographics on NLR except for age. Older patients had higher NLR (p 0.037). NLR showed a quicker return to normal than CRP. Our results show that NLR seems to be a better marker to follow inflammation after THA than CRP.

Fused micro-computed tomography (µCT) and histological images of bone specimens.

OBJECTIVES: To describe a stepwise process to obtain fused images from micro-computed tomography (µCT) and histological images of bone specimens. MATERIAL AND METHODS: Four surgically resected human femoral heads from four patients who had total hip replacement were imaged at a spatial resolution of 12-microns by using µCT. Histological sections of four focal bone lesions including bone cyst in osteoarthritis (n=2) and subchondral bone plate fracture in osteonecrosis (n=2) were prepared and digitized. µCT images were reformatted and adjusted to match the histological images using a landmark-based visual co-registration. Fused µCT and histological images were displayed in a cine-loop video mode with a gradual transition from one image to the other. RESULTS: µCT images of the four focal bone lesions could be successfully fused with the corresponding histological images with a near perfect match of the bone trabeculae. CONCLUSION: We present a stepwise process to obtain fused images from histological and reformatted µCT images of human femoral heads.

Diagnosis of prosthetic joint infection with alpha-defensin using a lateral flow device: a multicentre study.

AIMS: The purpose of this current multicentre study is to analyse the presence of alpha-defensin proteins in synovial fluid using the Synovasure lateral flow device and to determine its diagnostic reliability and accuracy compared with the prosthetic joint infection (PJI) criteria produced by the Musculoskeletal Infection Society (MSIS). PATIENTS AND METHODS: A cohort of 121 patients comprising 85 total knee arthroplasties and 36 total hip arthroplasties was prospectively evaluated between May 2015 and June 2016 in three different orthopaedic centres. The tests were performed on patients with a chronically painful prosthesis undergoing a joint aspiration in a diagnostic pathway or during revision surgery. RESULTS: Based on the MSIS criteria, 34 patients (28%) would have had a PJI, and 87 patients had no PJI. Testing with the lateral flow device had a sensitivity of 97.1% (95% confidence intervals (CI) 84.5 to 99.9) and a specificity of 96.6% (95% CI 90.3 to 99.2). The positive predictive value was 91.7% (95% CI 77.7% to 98.3), and the negative predictive value was 98.8% (95% CI 93.6 to 99.9). Receiver operator characteristics analysis demonstrated an area under the curve for the Synovasure test of 0.97 (95% CI 0.93 to 1.00). CONCLUSION: Our findings suggest that the Synovasure test has an excellent diagnostic performance to confirm or reject the diagnosis of a PJI. The results are promising for the care of the painful or problematic knee and hip joint arthroplasty and the test should be considered as part of the diagnostic toolbox for PJIs. Cite this article: Bone Joint J 2017;99-B:1176-82.

Radiation exposure to the patients in thoracic and lumbar spine fusion using a new intraoperative cone-beam computed tomography imaging technique: a preliminary study.

PURPOSE: The goals of this paper are to assess the ionizing radiation exposure to the patients during thoracic and lumbar spinal fusion using a new intraoperative 3D imaging system and to evaluate the factors that could explain the variability in the observed doses. METHOD: We retrospectively reviewed 97 patients who underwent posterior instrumented thoracic and/or lumbar spinal fusion from December 2013 to November 2014. Primary data were the total dose area product (total DAP, Gy cm2) and total skin dose (total SD, mGy). Influence of different variables (patient characteristics, surgical technique, and intraoperative imaging system parameters) that could influence patients' exposure was analyzed. RESULTS: Radiation dose imparted to patients depended on four parameters including acquisition protocol, surgical technique, patient's BMI and operative time. Minimally invasive surgery (MIS) resulted in twofold higher dose for patients, compared to open surgery. The use of low dose acquisition protocols reduced patient exposure by a factor three. CONCLUSION: Patient exposure was highly variable. Four parameters were found to explain about 68% of its variance when using a multi-axis robotic C-arm system. MIS technique (with navigation or not) as well as the acquisition protocol dramatically increases the radiation dose for patients. These results show the necessity to develop specific strategies adapted to patients and surgical procedures.