Patterns of pre-operative opioid use affect the risk for complications after total joint replacement

Preoperative opioid use has been shown to increase the risk for complications following total joint arthroplasty (TJA); however, these studies have not always accounted for differences in co-morbidities and socio-demographics between patients that use opioids and those that do not. They have also not accounted for the variation in degree of pre-operative use. The objective of this study was to determine if preoperative opioid use is associated with risk for surgical complications after TJA, and if this association varied by degree of use. Population-based retrospective cohort study. Older adult patients undergoing primary TJA of the hip, knee and shoulder for osteoarthritis between 2002 and 2015 in Ontario, Canada were identified. Using accepted definitions, patients were stratified into three groups according to their preoperative opioid use: no use, intermittent use and chronic use. The primary outcome was the occurrence of a composite surgical complication (surgical site infection, dislocation, revision arthroplasty) or death within a year of surgery. Intermittent and chronic users were matched separately to non-users in a 1:1 ratio, matching on TJA type plus a propensity score incorporating patient and provider factors. Overall, 108,067 patients were included in the study; 10% (N = 10,441) used opioids on a chronic basis before surgery and 35% (N = 37,668) used them intermittently. After matching, chronic pre-operative opioid use was associated with an increased risk for complications after TJA (HR 1.44, p = 0.001) relative to non-users. Overall, less than half of patients undergoing TJA used opioids in the year preceding surgery; the majority used them only intermittently. While chronic pre-operative opioid use is associated with an increased risk for complications after TJA, intermitted pre-operative use is not.

Design Approach for Reducing Cross-Axis Sensitivity in a Single-Drive Multi-Axis MEMS Gyroscope

In this paper, a new design technique is presented to estimate and reduce the cross-axis sensitivity (CAS) in a single-drive multi-axis microelectromechanical systems (MEMS) gyroscope. A simplified single-drive multi-axis MEMS gyroscope, based on a mode-split approach, was analyzed for cross-axis sensitivity using COMSOL Multiphysics. A design technique named the “ratio-matching method” of drive displacement amplitudes and sense frequency differences ratios was proposed to reduce the cross-axis sensitivity. Initially, the cross-axis sensitivities in the designed gyroscope for x and y-axis were calculated to be 0.482% and 0.120%, respectively, having an average CAS of 0.301%. Using the proposed ratio-matching method and design technique, the individual cross-axis sensitivities in the designed gyroscope for x and y-axis were reduced to 0.018% and 0.073%, respectively. While the average CAS was reduced to 0.045%, showing a reduction rate of 85.1%. Moreover, the proposed ratio-matching method for cross-axis sensitivity reduction was successfully validated through simulations by varying the coupling spring position and sense frequency difference variation analyses. Furthermore, the proposed methodology was verified experimentally using fabricated single-drive multi-axis gyroscope.

Patterns of pre-operative opioid use affect the risk for complications after total joint replacement

Background Preoperative opioid use has been shown to increase the risk for complications following total joint arthroplasty (TJA); however, these studies have not always accounted for differences in co-morbidities and socio-demographics between patients that use opioids and those that do not. They have also not accounted for the variation in degree of pre-operative use. The objective of this study was to determine if preoperative opioid use is associated with risk for surgical complications after TJA, and if this association varied by degree of use. Methods Population-based retrospective cohort study. Older adult patients undergoing primary TJA of the hip, knee and shoulder for osteoarthritis between 2002 and 2015 in Ontario, Canada were identified. Using accepted definitions, patients were stratified into three groups according to their preoperative opioid use: no use, intermittent use and chronic use. The primary outcome was the occurrence of a composite surgical complication (surgical site infection, dislocation, revision arthroplasty) or death within a year of surgery. Intermittent and chronic users were matched separately to non-users in a 1:1 ratio, matching on TJA type plus a propensity score incorporating patient and provider factors. Results Overall, 108,067 patients were included in the study; 10% (N=10,441) used opioids on a chronic basis before surgery and 35% (N=37,668) used them intermittently. After matching, neither intermittent nor chronic pre-operative opioid use were associated with an increased risk for complications after TJA. Conclusions Overall, less than half of patients undergoing TJA used opioids in the year preceding surgery; the majority used them only intermittently. Pre-operative opioid use is not associated with an increased risk for complications after TJA.

A Method for Identifying Pollution Sources of Heavy Metals and PAH for a Risk-Based Management of a Mediterranean Harbour

A procedure for assessing harbour pollution by heavy metals and PAH and the possible sources of contamination is proposed. The procedure is based on a ratio-matching method applied to the results of principal component analysis (PCA), and it allows discrimination between point and nonpoint sources. The approach can be adopted when many sources of pollution can contribute in a very narrow coastal ecosystem, both internal and outside but close to the harbour, and was used to identify the possible point sources of contamination in a Mediterranean Harbour (Port of Vado, Savona, Italy). 235 sediment samples were collected in 81 sampling points during four monitoring campaigns and 28 chemicals were searched for within the collected samples. PCA of total samples allowed the assessment of 8 main possible point sources, while the refining ratio-matching identified 1 sampling point as a possible PAH source, 2 sampling points as Cd point sources, and 3 sampling points as C > 12 point sources. By a map analysis it was possible to assess two internal sources of pollution directly related to terminals activity. The study is the prosecution of a previous work aimed at assessing Savona-Vado Harbour pollution levels and suggested strategies to regulate the harbour activities.