http://xoomer.virgilio.it/lusebra/NuoviFile/PrevenzioneTVP.pdf

Prevention of venous thromboembolism

https://www.chpso.org/sites/main/files/file-attachments/chest-2008-geerts-381s-453s.pdf

Prevention of Venous Thromboembolism* American College of Chest Physicians Evidence- Based Clinical Practice Guidelines (8th Edition)

Neuronal activity in the brain gives rise to transmembrane currents that can be measured in the extracellular medium. Although the major contributor of the extracellular signal is the synaptic transmembrane current, other sources — including Na+ and Ca2+ spikes, ionic fluxes through voltage- and ligand-gated channels, and intrinsic membrane oscillations — can substantially shape the extracellular field. High-density recordings of field activity in animals and subdural grid recordings in humans, combined with recently developed data processing tools and computational modelling, can provide insight into the cooperative behaviour of neurons, their average synaptic input and their spiking output, and can increase our understanding of how these processes contribute to the extracellular signal.

/pdf/the-origin-of-extracellular-fields-and-currents-eeg-ecog-lfp-2e79zygxj0.pdf

The origin of extracellular fields and currents — EEG, ECoG, LFP and spikes

Prevention of Venous Thromboembolism : The Seventh ACCP Conference on Antithrombotic and Thrombolytic Therapy

Background Reported risk factors for venous thromboembolism (VTE) vary widely, and the magnitude and independence of each are uncertain Objectives To identify independent risk factors for deep vein thrombosis and pulmonary embolism and to estimate the magnitude of risk for each Patients and Methods We performed a population-based, nested, case-control study of 625 Olmsted County, Minnesota, patients with a first lifetime VTE diagnosed during the 15-year period from January 1, 1976, through December 31, 1990, and 625 Olmsted County patients without VTE The 2 groups were matched on age, sex, calendar year, and medical record number Results Independent risk factors for VTE included surgery (odds ratio [OR], 217; 95% confidence interval [CI], 94-499), trauma (OR, 127; 95% CI, 41-397), hospital or nursing home confinement (OR, 80; 95% CI, 45-142), malignant neoplasm with (OR, 65; 95% CI, 21-202) or without (OR, 41; 95% CI, 19-85) chemotherapy, central venous catheter or pacemaker (OR, 56; 95% CI, 16-196), superficial vein thrombosis (OR, 43; 95% CI, 18-106), and neurological disease with extremity paresis (OR, 30; 95% CI, 13-74) The risk associated with varicose veins diminished with age (for age 45 years: OR, 42; 95% CI, 16-113; for age 60 years: OR, 19; 95% CI, 10-36; for age 75 years: OR, 09; 95% CI, 06-14), while patients with liver disease had a reduced risk (OR, 01; 95% CI, 00-07) Conclusion Hospital or nursing home confinement, surgery, trauma, malignant neoplasm, chemotherapy, neurologic disease with paresis, central venous catheter or pacemaker, varicose veins, and superficial vein thrombosis are independent and important risk factors for VTE

https://jamanetwork.com/journals/jamainternalmedicine/articlepdf/485266/ioi90392.pdf

Risk factors for deep vein thrombosis and pulmonary embolism: a population-based case-control study.

The survivorship method of analysis was used to compare the failure rate and overall success of 2629 cemented primary total knee arthroplasties during a 22-year period by the senior surgeon. There were 215 Total Condylar prostheses with a polyethylene tibia, 265 of the Posterior Stabilized type with an all polyethylene tibia, 2036 Posterior Stabilized with a metal backed tibial component, 49 Posterior Stabilized with modular augmented components, and 64 with the Constrained Condylar system. Failure was considered revision or planned revision. The Total Condylar series had an average annual failure rate of 0.46% and a 21-year success rate of 90.77%. The Posterior Stabilized prosthesis with an all polyethylene tibia had an average annual rate of failure of 0.38% and a 16-year success rate of 94.10%, and this prosthesis with a metal backed tibial component had an annual failure rate of 0.14% and a 14-year success rate of 98.10%. The Posterior Stabilized series with modular components had an average annual rate of failure of 0.59% and a 10-year success rate of 93.63%. The Constrained Condylar knee series had an average annual failure rate of 0.26% and a 7-year success rate of 98.12%. This review represents a retrospective analysis of consecutive series of cemented, total knee arthroplasties, whose annual failure and success rates were done during differing time spans. The overall success rate was not influenced by gender, age, diagnosis, or percentage of ideal body weight. Failure was considered revision or planned revision. The best and worse case scenarios were calculated for each series. Long term results of cemented, total knee arthroplasty with a relatively conforming articular surface has been shown to be a reliable procedure with excellent survivorship.

Survivorship of cemented total knee arthroplasty.

In 1989, The Knee Society Clinical Rating System [3] was developed as a simple, but objective scoring system to rate the knee and patient’s functional abilities such as walking and stair climbing before and after TKA. Since the scoring system did not include assessment of radiographs, The Knee Society endorsed a method to evaluate radiographs [2]. The Knee Society Clinical Rating System has been the most popular method of tracking and reporting outcomes after total and partial knee arthroplasty worldwide. However, the reliability, responsiveness, and validity of the original score have been challenged. In addition, it became clear over time that there were ambiguities and deficiencies with the original Knee Society Clinical Rating System that challenged its utility and validity in our contemporary patients, who often have expectations, demands, and functional requirements that are different from those of prior generations of patients who underwent knee arthroplasty.

The Knee Society therefore embarked on a complete review of the previous system. The project started more than 3 years ago and involved Knee Society members from 18 institutions in the United States and Canada; these individuals contributed more than 500 cases of both preoperative and postoperative TKA. The magnitude of this exhaustive project involved a multidisciplinary team of arthroplasty surgeons, epidemiologists, and statisticians. The prior objective knee score was amplified from the prior Knee Society score to incorporate current knee arthroplasty clinical parameters. The functional component of the new score was developed on the basis of comprehensive inventories of the activities and observations of 101 patients at five major knee arthroplasty centers who completed a 120-item survey, which was ultimately condensed down to the current assessment tool. This assessment tool was then included in the validation process at the 18 participating centers. The final scoring system was then approved by the Knee Society Scoring Committee.

The new Knee Society Knee Scoring System is both physician and patient derived. It includes versions to be administered preoperatively (Appendix 1) and postoperatively (Appendix 2). It has an initial assessment of demographic details, including an expanded Charnley functional classification [1]. The objective knee score, completed by the surgeon, includes a VAS score of pain walking on level ground and on stairs or inclines, as well as an assessment of alignment, ligament stability, and ROM, along with deductions for flexion contracture or extensor lag. Patients then record their satisfaction, functional activities, and expectations. Given the diverse activity profiles of many contemporary patients, the functional component of the score was improved to include a patient-specific survey, which evaluates features such as standard activities of daily living, patient-specific sports and recreational activities, patient satisfaction, and patient expectations. Portions of the original Knee Society Clinical Rating System have been integrated into the new version to maintain the integrity of the prior version of the Knee Society score.

The new Knee Society Knee Scoring System has been developed and validated, in part, to better characterize the expectations, satisfaction, and physical activities of the younger and more diverse population of current patients undergoing TKA. The new score provides sufficient flexibility and depth to capture the diverse lifestyles and activities of our current patients. The score was validated in a thoughtful and methodical fashion confirming internal reliability and analyzed for differential item functioning [4]. The new Knee Society Scoring System is broadly applicable across sex, age, activity level, and implant type.

In conclusion, the new Knee Society Scoring System is a validated and responsive method for assessing objective and subjective outcomes after total and partial knee arthroplasty, without the ambiguities of the prior scoring system. As physicians, clinical practices, and health systems become increasingly more responsible for reporting patient outcomes, the clear value of this new scoring system will become apparent. The new scoring system is available through application on the Knee Society Web site (http://www.kneesociety.org).

/pdf/the-new-knee-society-knee-scoring-system-4ibhj6xbxg.pdf

The new Knee Society Knee Scoring System.

In 100 knees undergoing a total replacement, the angles between the tangent line of the posterior condylar surfaces, the anteroposterior axis as described by Whiteside, the transepicondylar line, and the trochlear line were measured. Also measured were the sulcus angle, the transepicondylar width, the height of the condyles, and the thickness of the various cuts. Radiologic measurements made were: the mechanical angle, the hip center-femoral shaft angle, the transcondylar angle, and the tibial plateau-tibial shaft angle. The mean values of these measurements were calculated, and comparisons were made according to gender and the mechanical axis using the Student's t test. Correlations between the various measurements were calculated. The transepicondylar axis was found to be a reliable landmark to properly rotate the femoral component, and was easier to locate at surgery than the anteroposterior axis. In trochlear dysplasia and in some valgus knees, relying on the anteroposterior axis can induce an excessive external rotation of the femoral component, and the opposite can happen in some varus knees. The anterior extent of the condyles is highly variable in arthritic knees, and cannot be used to orient the prosthesis. The ratio between the transepicondylar width and the height of the condyles is constant, but some narrow femora could require narrower implants to avoid medial-lateral overhang of the femoral component.

/pdf/rotational-landmarks-and-sizing-of-the-distal-femur-in-total-s7ukqnn817.pdf

Rotational Landmarks and Sizing of the Distal Femur in Total Knee Arthroplasty

The survivorship method of analysis has been used to compare the failure rate and overall success of 1,430 cemented primary total knee arthroplasties performed at The Hospital for Special Surgery over a 15-year period. There were 224 total condylar prostheses with a polyethylene tibia, 289 of the posterior stabilised type with an all polyethylene tibia, and 917 posterior stabilised with a metal-backed tibial component. There were 12 failures in the total condylar series, giving an average annual failure rate of 0.65% and a 15-year success rate of 90.56%. The posterior stabilised prosthesis with a polyethylene tibia showed an average annual failure rate of 0.27% and a 10-year success rate of 97.34%, and this prosthesis with a metal-backed tibial component gave an annual failure rate of 0.19% and a seven-year success rate of 98.75%. The overall survival rate was not influenced by sex or age, diagnosis or the percentage of ideal body weight. No metal-backed tibial components have yet needed revision for loosening. It seems that infection will be the major cause of failure.

Giles R. Scuderi

Papers

Survivorship of cemented total knee arthroplasty.

The new Knee Society Knee Scoring System.

Rotational Landmarks and Sizing of the Distal Femur in Total Knee Arthroplasty

Survivorship of cemented knee replacements

The Basic Principles