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Bone & Joint Research
Vol. 11, Issue 1 | Pages 23 - 25
17 Jan 2022
Matar HE Platt SR Bloch BV Board TN Porter ML Cameron HU James PJ


The Bone & Joint Journal
Vol. 105-B, Issue 6 | Pages 602 - 609
1 Jun 2023
Mistry D Ahmed U Aujla R Aslam N D’Alessandro P Malik S

Aims. In the UK, the agricultural, military, and construction sectors have stringent rules about the use of hearing protection due to the risk of noise-induced hearing loss. Orthopaedic staff may also be at risk due to the use of power tools. The UK Health and Safety Executive (HSE) have clear standards as to what are deemed acceptable occupational levels of noise on A-weighted and C-weighted scales. The aims of this review were to assess the current evidence on the testing of exposure to noise in orthopaedic operating theatres to see if it exceeds these regulations. Methods. A search of PubMed and EMBASE databases was conducted using PRISMA guidelines. The review was registered prospectively in PROSPERO. Studies which assessed the exposure to noise for orthopaedic staff in operating theatres were included. Data about the exposure to noise were extracted from these studies and compared with the A-weighted and C-weighted acceptable levels described in the HSE regulations. Results. A total of 15 studies were deemed eligible. These included a total of 386 orthopaedic operations and the use of 64 orthopaedic instruments. A total of 294 operations (76%) and 45 instruments (70%) exceeded the regulations on an A-weighted scale, and 22% (10 of 46) of operations exceeded the maximum C-weighted peak acceptable level of noise. Noise-induced hearing loss was reported in 28 of 55 orthopaedic staff members (50.9%). Conclusion. Safe levels of noise can be exceeded in orthopaedic operations, and when using orthopaedic instruments. Employers have clear policies about exposure to noise in the workplace but have yet to identify orthopaedic theatres as a potential at-risk area. Orthopaedic staff need education, monitoring, and protection, while employers should consider regular assessments of staff in orthopaedic theatres and offer methods to prevent noise-induced hearing loss. Cite this article: Bone Joint J 2023;105-B(6):602–609


Orthopaedic Proceedings
Vol. 85-B, Issue SUPP_II | Pages 124 - 124
1 Feb 2003
McGregor-Riley J Ali F Hussainy HA Sukumar S
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This study examines the value of a proforma in improving the standards of orthopaedic operation notes. The standard of operation notes in orthopaedic surgery is notoriously poor. This has clinical, medicolegal and research implications. There is no published study on the influence of a proforma on the quality of orthopaedic operation notes. An audit of the quality of operation notes in the orthopaedic department of Chesterfield and North Derbyshire Royal Hospital was undertaken. 1, 928 cases were identified from theatre log books and 88 randomly selected casenotes were scrutinised by a single observer for the legible inclusion of parameters based on Royal College of Surgeons guidelines. An operation note proforma was devised and used routinely over a period of six weeks. The effectiveness of the proforma was assessed by examining operation notes randomly selected from the procedures performed during that period. Identical parameters were assessed. Results from the two groups were compared and statistically analysed using the Wilcoxon signed ranks test. To investigate the longer term impact of proformas an identical audit was undertaken in a neighbouring unit in which a proforma had been in use for five years. Following introduction of the proforma in Chesterfield there was a statistically significant increase in the inclusion of the assessed parameters (p=0. 001). Criteria such as the patient ID number, pre-op diagnosis, tourniquet use and time, prophylactic antibiotic administration, prosthesis details and post-op instructions showed a marked improvement. No parameter showed a significant reduction in its documentation rate. The results from Rotherham were comparable to those achieved following the introduction of the proforma in Chesterfield. This study clearly demonstrates the effectiveness of a proforma in improving the standard of operation notes. The results from Rotherham suggest that high standards can be maintained long after the introduction of the proforma. We recommend the routine use of operation note proformas in orthopaedic surgery


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_II | Pages 264 - 264
1 Jul 2008
IRRAZI M SELLIES J BERRICHI A BEAU P IONESCU N CUNY C
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Purpose of the study: Surveillance of operative site infections (OSI) is a persistent problem in orthopedic surgery. In France, a specific administrative directive was issued on December 29, 2000 to regulate surveillance of OSI. Material and methods: Based on evidence reported in the literature, the efficacy of any surveillance plan requires a sufficiently dense data base obtained by long-term and systematic registration of all significant information concerning all orthopedic surgery patients. Of particular importance are the ASA score, Altmeier, and antibiotic prophylaxy. During the five-year period from 1999 through 2004, a total of 8811 consecutive orthopedic surgery procedures were followed prospectively. Infections detected were registered using a dedicated software. The hospital hygiene committee and the referring surgeon performed the follow-up. Results: On average, infection developed four months after surgery. The rate of infection was 1.2% in 1999 and declined to 0.6% in 2003 with the implementation of a few prophylactic measures. It was possible to determine which operations and which patients were at risk using as criteria the type of operation and the ASA score. Discussion: Surveillance of OSI, with adjustment for risk factors, enabled a measurement of the risk of infection and enabled us to recognized a trend within our department. This study enabled us to define the level of risk for our patients and also develop a new preventive policy. Our findings led us to modify certain practices. Certain data reported in the literature concerning antibiotic prophylaxy were confirmed. Conclusion: This work demonstrated the importance of following operative site infections, disclosed the implications for medical and hospital personnel, and demonstrated the efficacy of preventive measures for decreasing the rate of these infections


Orthopaedic Proceedings
Vol. 95-B, Issue SUPP_15 | Pages 45 - 45
1 Mar 2013
Conditt M Branch SH Ballash M Granchi C
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INTRODUCTION. Adult reconstructive orthopedic surgery in the United States is facing an imminent logjam due to the increasing divergence of the demand for services and the ability for the community to supply those services. In combination with several other factors, a perfect storm is brewing that may leave the system overtaxed and the patient population suffering from either a lack of treatment, or treatment by less qualified providers. A key component to improving the overall efficiency of surgical care is to introduce enabling technologies that can effectively increase the throughput while simultaneously improving the quality of care. One such enabling technology that has proven itself in many industries is robotics, which has recently been introduced in surgery with even more recent applications in orthopedic surgery. A surgeon interactive robotic arm has been developed for partial knee arthroplasty (PKA) and total hip arthroplasty (THA). This study aims to analyse the efficiency of a new robotic technology for use in orthopaedic surgery. METHODS. 18 robotic arm assisted PKA's across 10 sites were recorded to accurately capture the timeline elemental tasks throughout the procedure. Two camera angles were set up to capture both surgical staff group dynamics and individual procedural steps. 17 tasks were identified and measured from video data. (Fig 1) The robotic arm specific tasks were analyzed for correlation to total surgical time (measured as first incision to last suture). The tasks for the surgeons with the shortest and longest total times were compared directly to determine areas of opportunity. RESULTS. Average total time across 18 surgeries was 55 ± 19 min (range: 30–98 min). There was no correlation between bone registration time and total time (p=0.271) and no correlation between femoral burring time and total time (p=0.230). Per task time comparison of the two surgeons exhibited an average time variation of 3.5 min per task (range: 0.7–8.4 min) (Fig 2). The robotic elements of the procedure exhibited an average time variation of 3.3 min per task while the non robotic elements of the procedure (boxed) exhibited an average time variation of 3.8 min per task. CONCLUSION. Our preliminary results indicate that introducing robotic technology in to the OR does not directly lead to an increase in total surgical time. On average, non robotic specific elements of the procedure exhibited a larger opportunity for efficiency gain. This is likely due to the fact that a large population of surgeon users are not only new to the robotic technology, but new to PKA. Further video collection and analysis will lead to an efficiency benchmarking program that aims to establish methods for best practices in achieving efficiency throughout a robotic arm assisted PKA procedure


Bone & Joint Open
Vol. 4, Issue 2 | Pages 96 - 103
14 Feb 2023
Knowlson CN Brealey S Keding A Torgerson D Rangan A

Aims

Early large treatment effects can arise in small studies, which lessen as more data accumulate. This study aimed to retrospectively examine whether early treatment effects occurred for two multicentre orthopaedic randomized controlled trials (RCTs) and explore biases related to this.

Methods

Included RCTs were ProFHER (PROximal Fracture of the Humerus: Evaluation by Randomisation), a two-arm study of surgery versus non-surgical treatment for proximal humerus fractures, and UK FROST (United Kingdom Frozen Shoulder Trial), a three-arm study of two surgical and one non-surgical treatment for frozen shoulder. To determine whether early treatment effects were present, the primary outcome of Oxford Shoulder Score (OSS) was compared on forest plots for: the chief investigator’s (CI) site to the remaining sites, the first five sites opened to the other sites, and patients grouped in quintiles by randomization date. Potential for bias was assessed by comparing mean age and proportion of patients with indicators of poor outcome between included and excluded/non-consenting participants.


Orthopaedic Proceedings
Vol. 90-B, Issue SUPP_I | Pages 54 - 54
1 Mar 2008
Furey A Stone C Martin R
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Wrong site surgery is a preventable problem. In 1994 the Canadian Orthopaedic Association (COA) began an educational program initiated to prevent such mistakes from occurring. The purpose of this study was to assess the proportion of orthopedic surgeons who mark their sites preoperatively. This study confirms a high proportion (74.9%) of surgeons in Canada follow the COA guidelines at least occasionally with over half (52.1%) consistently “signing their sites.”. Wrong site surgery is often a catastrophic, but preventable problem. Reports of wrong site surgery have been on the rise in the United States every year since 1995. In 1994 the Canadian Orthopaedic Association (COA) began an educational program initiated to prevent such mistakes from occurring. Their recommendations involved marking the incision site preoperatively. Since that time the claims of wrong site orthopedic surgery have diminished. The purpose of this study was to assess the proportion of orthopedic surgeons who mark their sites preoperatively. Two hundred orthopedic surgeons across Canada were asked to complete a survey concerning preoperative incision site marking. A response rate of 89.3% was achieved. Eighty seven (52.1%) stated they always marked their incision site, thirty eight (22.8%) stated they occasionally marked their incision site, while forty two (25.1%) claimed to never mark their incision site preoperatively. Surgeons in academic centers were more likely to sign their sites than their community counterparts (p=0.021) and surgeons in practice longer were less likely to comply with the COA recommendation (p=0.023). The COA and American Academy of Orthopedic Surgeons (AAOS) have recommended marking incision sites preoperatively in an attempt to reduce wrong site surgery. This study confirms a high proportion (74.9%) of surgeons in Canada follow the COA guidelines at least occasionally with over half (52.1%) consistently “signing their sites.”


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_II | Pages 337 - 338
1 May 2006
Ilsar I Weil Y Mosheiff R Joskowicz L Peyser A Liebergall M
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Introduction: To enable navigated-assisted orthopedic surgery, a reference frame must be rigidly fixed to a stable bony structure. This may create technical obstacles and wound complications. Instead, we propose to attach the reference frame to the fracture table. Methods: The study population consisted of 10 patients who underwent fixation of subcapital femoral neck fracture with three cannulated screws, using fluoroscopy-based navigation. Step 1 – the patient was positioned on a fracture table and the reference frame was attached to the iliac crest. Three guide wires were inserted under fluoroscopy-based navigation. 2 – New fluoroscopic images were acquired. 3 – Navigated drill guide placed over each guide wire to record final navigated drill guide position – these images include actual guide wire positions and the trajectories of the navigated drill guide. Navigation accuracy was validated, measuring translational and angular deviations of the virtual trajectory from the implant on the same fluoroscopic image in anteroposterior and lateral views. 4 – The reference frame was removed from the iliac crest and attached to the fracture table. Step 3 was then repeated. Results: The translational deviation of the virtual trajectory from the inserted guide wire when the reference frame was attached to the iliac crest was not statistically significant from the deviation when it was attached to the fracture table. Angular differences were also not statistically significant. Conclusions: In our experience, attaching the reference frame to the fracture table instead of to the iliac crest allows for similar accuracy of the navigation process with the possible benefit of reducing patient morbidity


Orthopaedic Proceedings
Vol. 93-B, Issue SUPP_IV | Pages 561 - 561
1 Nov 2011
Gandhi R Rampersaud YR Mahomed NN Hudak P Veillette C Syed K Lewis S Davey JR
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Purpose: Factors influencing patient willingness to undergo elective surgery are poorly understood. Method: We prospectively evaluated patient concerns prior to surgical consultation for elective spinal, hip, knee, shoulder/elbow (S/E), or foot/ankle (F/A) conditions. Patients were surveyed for demographic data, SF 36 quality of life (QOL) scores and asked to report their greatest concern about considering surgery for their condition, as well as their willingness to undergo surgery if it was offered to them by their treating surgeon. Results: In our prospective cohort of 743 patients, 364 (51%) were male and 293 (39 %) were evaluated for a spine condition, 74 (10 %) hip, 192 (26 %) knee, 69 (9 %) S/E, and 115 (16 %) F/A. Mean QOL scores were similar for patients across specialities. The top three greatest concerns for undergoing elective musculoskeletal surgery were potential complications (20%), effectiveness (15%) and recovery time (15%) of surgery. When categorized by specialty, concern of surgical complications was the most prevalent in spine (23%) and F/A patients (30%). However, patients were most commonly unsure of risks associated with their respective subspecialty surgery (spine – 56%; hip – 53%; knee – 44%; S/E – 48% and F/A – 33%). The majority of hip patients (89%) perceived a high success rate for hip surgery, while 65% of spine patients where unsure of the success of spine surgery. Patient willingness to undergo surgery was greatest for hip (84%), knee (78%), and S/E (82%) surgery and least for spine (68%) and F/A surgery (74%). Conclusion: Although patient willingness to consider surgery is clearly a multifactorial decision, patient perception of surgical risk or success prior to surgical consultation are significant factors


Bone & Joint Open
Vol. 4, Issue 2 | Pages 104 - 109
20 Feb 2023
Aslam AM Kennedy J Seghol H Khisty N Nicols TA Adie S

Aims

Patient decision aids have previously demonstrated an improvement in the quality of the informed consent process. This study assessed the effectiveness of detailed written patient information, compared to standard verbal consent, in improving postoperative recall in adult orthopaedic trauma patients.

Methods

This randomized controlled feasibility trial was conducted at two teaching hospitals within the South Eastern Sydney Local Health District. Adult patients (age ≥ 18 years) pending orthopaedic trauma surgery between March 2021 and September 2021 were recruited and randomized to detailed or standard methods of informed consent using a random sequence concealed in sealed, opaque envelopes. The detailed group received procedure-specific written information in addition to the standard verbal consent. The primary outcome was total recall, using a seven-point interview-administered recall questionnaire at 72 hours postoperatively. Points were awarded if the participant correctly recalled details of potential complications (maximum three points), implants used (maximum three points), and postoperative instructions (maximum one point). Secondary outcomes included the anxiety subscale of the Hospital and Anxiety Depression Scale (HADS-A) and visual analogue scale (VAS) for pain collected at 24 hours preoperatively and 72 hours postoperatively. Additionally, the Patient Satisfaction Questionnaire Short Form (PSQ-18) measured satisfaction at 72 hours postoperatively.


Orthopaedic Proceedings
Vol. 92-B, Issue SUPP_I | Pages 84 - 84
1 Mar 2010
Minguez JP Otero RC Sixto AG Follente JC
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Introduction and Objectives: In this study we attempted to analyze the biocompatibility of 3 different materials used in Orthopedic Surgery, Titanium, Tantalum and Hydroxyapatite, measuring their adsorption of fibrinogen by means of real time in vitro studies quantifying the mass of fibrinogen that becomes deposited on them. Materials and Methods: We assessed fibrinogen adsorption on these biomaterials by means of quantitative studies using the QCM-D system and qualitative studies reviewing fibrinogen adhesion, by atomic microscopy. For the statistical analysis of the results of this study we used SSP 14.0. Results: The results of the measurement of fibrinogen adsorption on the biomaterials used proved that when low concentrations of fibrinogen were used, 33 ng/ml, Ti and Ha adsorbed fibrinogen relatively rapidly, but Ta does not. However, when we used high concentrations of fibrinogen, 100 ng/ml, Ta adsorption increased markedly. When concentrations greater than 1000 ng/ml of fibrinogen were used, Ta was the biomaterial that showed most fibrinogen adsorption. Discussion and Conclusions: The adsorption of proteins from body fluids is the first biological response to the implantation of a biomaterial, and this protein adhesion will guide cell adhesion on the implanted biomaterial. In our in vitro study, carrying out measurements in real time, we saw that Ta was the material with greatest biocompatibility


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_II | Pages 156 - 156
1 Feb 2004
Konstantopoulos G Konstantopoulos K Papaioannou E Dounis E Proveleggios S Kostakis S Tsinari K
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Aim: Our aim was to record our experience with a fine needle 27G with any possible difficulties and side-effects. Methods: 38 patients (26 men, 12 women) were selected for our study, aged 18–33 years. The underwent orthopedic surgery (femoral fractures, ankle surgery, patella, tibia and fibula fractures). The patients were preloaded with 500–700 ml crystalloid fluids.Lignocaine 2% (2–4ml) was injected for skin infiltration. The spinal was performed in lateral positioning in O3–O4 or O4–O5 spaces. Bupivacaine (Marcaine 0.5%) was injected and clonidine (Catapresan) was added in 8 cases for prolonged anaesthesia. The injection was slow and the patients were evaluated in 1, 12, 24, 48 hours. Results: Headache – technical difficulties – delayed action – nausea and vomiting and urine retention were recorded. Headache. Even though all the patients were well informed for 24th bed rest, 2 of them suffered headache. They were treated with fluids, paracetamol, bed rest. No headache was noted after 72 hours. Technical difficulties. Multiple tries were needed for successful spinal in 3 obese patients. Delayed action. In 4 cases the onset of spinal anaesthesia took more than 20min. One patient was finally given general anaesthesia because of the spinal failure. No urine retention was recorded. Nausea – vomiting. 3 patients suffered nausea and were given ondasertron. No vomiting was recorded. Conclusion: We conclude that spinal anaesthesia in young patients doesn’t cause severe side-effects nor technical difficulties. Headache, nausea, vomiting are less common in spinal than general anaesthesia


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 233 - 233
1 Mar 2004
Eriksson B Bauer K Lassen M Turpie A
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Aims: In major orthopedic surgery, fondaparinux provided a major benefit over enoxaparin, with an overall venous thromboembolsim (VTE) risk reduction of > 50% and similar safety profile regarding clinically relevant bleeding (leading to death or reoperation, or occurring in critical organ). The aim of the present study was to analyze this superior efficacy according to patients and surgery characteristics. Methods: In four phase III trials, the primary efficacy outcome was the VTE incidence up to day 11, defined as deep-vein thrombosis (DVT) detected by mandatory bilateral venography or documented symptomatic DVT or pulmonary embolism. Primary efficacy was further analyzed according to predefined categorical covariates using a logistic regression model. Results: Fondaparinux was more effective than enoxaparin irrespective of age, gender, obesity, the use of cement or surgery duration (odds reduction from −46.9% to −59.7% in favor of fondaparinux. Clinically relevant bleeding did not differ between the two groups according to predefine covariates. Conclusions: For VTE prevention in major orthopaedic surgery, the superiority of fondaparinux over enoxaparin was consistent irrespective of patient or surgery characteristics


Bone & Joint Open
Vol. 4, Issue 9 | Pages 704 - 712
14 Sep 2023
Mercier MR Koucheki R Lex JR Khoshbin A Park SS Daniels TR Halai MM

Aims

This study aimed to investigate the risk of postoperative complications in COVID-19-positive patients undergoing common orthopaedic procedures.

Methods

Using the National Surgical Quality Improvement Programme (NSQIP) database, patients who underwent common orthopaedic surgery procedures from 1 January to 31 December 2021 were extracted. Patient preoperative COVID-19 status, demographics, comorbidities, type of surgery, and postoperative complications were analyzed. Propensity score matching was conducted between COVID-19-positive and -negative patients. Multivariable regression was then performed to identify both patient and provider risk factors independently associated with the occurrence of 30-day postoperative adverse events.


Orthopaedic Proceedings
Vol. 88-B, Issue SUPP_I | Pages 6 - 6
1 Mar 2006
Borris LC
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According to the 2004 ACCP guidelines on antithrombotic and thrombolytic therapy general extended prophylaxis with low molecular weight heparins, vitamin K antagonists, or fondaparinux is recommended after major orthopedic surgery. This recommendation is based on a number of placebo controlled, clinical studies using venographic screening for deep vein thrombosis (DVT), as a surrogate end-point for pulmonary embolism (PE), other vascular thrombotic events were not considered. In a recent meta-analysis on these studies the overall event rate of symptomatic venous thromboembolism 30–42 days after a joint arthroplasty was 2.7% DVT and 0.6 % PE in patients having short-term prophylaxis and it was significantly reduced by extended prophylaxis. Bleeding episodes were seen in 4% of cases having extension. Taking into consideration the risk benefit for the individual patient do these findings justify that extended prophylaxis is used on a general basis? To answer this question also compliance, adverse event profile, and cost of the prophylactic regimens have to be addressed. It would be very attractive to be able to individualize the duration of the prophylactic period by assessing the thrombotic potential of every patient in order to balance the risks and benefits of continued prophylaxis


Orthopaedic Proceedings
Vol. 86-B, Issue SUPP_III | Pages 232 - 232
1 Mar 2004
Eriksson B Bauer K Lassen M Turpie A
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Aims: The fondaparinux thromboprophylaxis phase III studies database including 7344 patients in orthopaedic surgery provides information regarding patient management according to country specificities. Methods: 4 randomized double-blind trials were conducted in 376 centers in 23 countries comparing fondaparinux to enoxaparin – 1 in major knee surgery (MKS) in North America (NA); 2 in total hip replacement (THR) in NA and in Europe, respectively; and 1 in hip-fracture (HF) surgery worldwide except in NA. The use of regional anesthesia or cement during surgery, use of stockings during hospitalization, or prolonged prophylaxis (PP) after discharge were left to the investigators. Results: In all studies the majority of patients were women, particularly in HF. The median age was 67 years for THR, 69 years for MKS, and 79 years for HF. In THR studies, regional anesthesia was used more frequently in Europe (59%) than in NA (24.4%). The table summarizes investigators’ practice. Conclusions: There are important differences in the management of orthopedic surgery patients according to country specificities and type of surgery. However, fondaparinux is more effective than enoxaparin for thromboprophylaxis irrespective of patient or surgery characteristics


Bone & Joint Open
Vol. 1, Issue 5 | Pages 93 - 97
6 May 2020
Giorgi PD Gallazzi E Capitani P D’Aliberti GA Bove F Chiara O Peretti G Schirò GR

The COVID-19 virus is a tremendous burden for the Italian health system. The regionally-based Italian National Health System has been reorganized. Hospitals' biggest challenge was to create new intensive care unit (ICU) beds, as the existing system was insufficient to meet new demand, especially in the most affected areas. Our institution in the Milan metropolitan area of Lombardy, the epicentre of the infection, was selected as one of the three regional hub for major trauma, serving a population of more than three million people. The aims were the increase the ICU beds and the rationalization of human and structural resources available for treating COVID-19 patients. In our hub hospital, the reorganization aimed to reduce the risk of infection and to obtained resources, in terms of beds and healthcare personnel to be use in the COVID-19 emergency. Non-urgent outpatient orthopaedic activity and elective surgery was also suspended. A training programme for healthcare personnel started immediately. Orthopaedic and radiological pathways dedicated to COVID-19 patients, or with possible infection, have been established. In our orthopaedic department, we passed from 70 to 26 beds. Our goal is to treat trauma surgery's patient in the “golden 72 hours” in order to reduce the overall hospital length of stay. We applied an objective priority system to manage the flow of surgical procedures in the emergency room based on clinical outcomes and guidelines. Organizing the present to face the emergency is a challenge, but in the global plan of changes in hospital management one must also think about the near future. We reported the Milan metropolitan area orthopaedic surgery management during the COVID-19 pandemic. Our decisions are not based on scientific evidence; therefore, the decision on how reorganize hospitals will likely remain in the hands of individual countries.




Background: Postoperative thromboses are among the most feared complications in orthopedic surgery, possibly causing life-threatening conditions in otherwise highly successful procedures such as total joint replacement. Body weight is an important risk factor for thromboses and is being used in algorithms to determine dosages in prophylaxis. However, weight patterns among orthopedic populations have changed considerably since the introduction of these algorithms, essentially shifting towards obesity. This study asks whether present-day obese patients are essential under-dosed and would benefit from higher than usual dosages of bemiparin sodium in the prophylaxis of postoperative thrombosis. Patients and Methods: To ensure sufficient power a sample of 750 patients, allocated into two cohorts receiving either 3,500 IU or 5,00o IU bemiparin sodium were followed postoperatively for 6 weeks and blindly assessed for clinically symptomatic thrombotic events. Differences in rates of thrombotic events were modeled using mulitvariate Poisson regression including potential confounders severity of immobilisation, gender, exact weight, and age as covariates. A p-value of 5% was considered significant. Results: Information on 723 patients for a total of 66.8 person-years was analysed per intention-to-treat. The adjusted incidence rate ratio was 0.35 (95%CI: 0.03 to 2.91). Thus there was not evidence for a difference in rates between groups. There was, however, a borderline significant association between rates and body weight, suggesting a potential benefit of higher dosages in even heavier patients. There were no complications due to higher dosages of bemiparin sodium. Conclusion: We did not see a significant reduction of incidence rates of thromboses with higher dosages of bemiparin in this population. However, there was some evidence that higher dosages might prove beneficial as populations further gain weight