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This paper has measured local traffic density under real driving conditions. The methodology employed is based on the traditional process of image recording. However, the conventional method has suffered from three typical limitations: long processing times, low vehicle detection performance, and inaccurate road length estimates. This study proposed two sequential approaches to resolve the three drawbacks. First, the you-only-look-once (YOLO) algorithm was used to shorten the computation time and enhance vehicle detection accuracy. Second, the vanishing point was identified during digital image processing to adjust the vertical and horizontal curves of roads, thereby calculating accurate road lengths. The proposed framework was applied to an arterial road in Seoul, South Korea. This approach was fast enough to measure local traffic density in real time. The performance of vehicle detection evaluated using a weighted mean average precision (mAP) was high at 88.73%. The accuracy of estimated road lengths evaluated using the Pearson correlation coefficient was also high at 0.97. Some co-benefits expected from the proposed method are also discussed.

Synovial chondromatosis is a benign metaplastic disease of the synovial joints, characterized by the development of cartilaginous nodules in the synovium. Treatment generally includes open or arthroscopic loose body removal combined with a synovectomy. An all-arthroscopic approach has been described to minimize complications and reduce morbidity while providing adequate control of local disease. The purpose of this Technical Note is to describe our techniques and technical pearls that allow for adequate excision of disease while minimizing complications and disease recurrence. The combination of patient positioning, the establishment of multiple arthroscopic portals to ensure optimal visualization and freedom of instruments, the use of a leg holder, and the use of a variety of surgical instruments to facilitate loose body removal and synovectomy is critical to optimize clinical outcomes and minimize complications. Although technically demanding, our described technique can help facilitate extensive loose body removal and complete synovectomy., Technique Video Video 1 Surgical tips and techniques for systematic arthroscopic treatment of synovial chondromatosis of the knee. A case presentation outlining the clinical findings and relevant magnetic resonance imaging (sagittal and axial views) in a patient with this condition is provided. First, the relevant surface anatomy and the location of our arthroscopic portals are reviewed. Drainage of a significant knee effusion is then shown, whereby loose bodies can be found within the synovial fluid. A standard diagnostic arthroscopy is performed, and our technique of using multiple shavers, electrocautery, and various graspers to effectively remove embedded loose bodies within the synovium is described. To identify loose bodies and the nearby structures that must be protected, the compartments of the knee, intercondylar notch, and submeniscal regions are addressed. To access difficult regions of the knee, techniques such as shaving through the notch, using a modified Gillquist maneuver, and debriding with a trans-septal approach in the posterior aspect of the knee are reviewed. Finally, intraoperative images of our biopsy procedures and specimens are shown.

Limb alignment in total knee arthroplasty (TKA) influences periarticular soft-tissue tension, biomechanics through knee flexion, and implant survival. Despite this, there is no uniform consensus on the optimal alignment technique for TKA. Neutral mechanical alignment facilitates knee flexion and symmetrical component wear but forces the limb into an unnatural position that alters native knee kinematics through the arc of knee flexion. Kinematic alignment aims to restore native limb alignment, but the safe ranges with this technique remain uncertain and the effects of this alignment technique on component survivorship remain unknown. Anatomical alignment aims to restore predisease limb alignment and knee geometry, but existing studies using this technique are based on cadaveric specimens or clinical trials with limited follow-up times. Functional alignment aims to restore the native plane and obliquity of the joint by manipulating implant positioning while limiting soft tissue releases, but the results of high-quality studies with long-term outcomes are still awaited. The drawbacks of existing studies on alignment include the use of surgical techniques with limited accuracy and reproducibility of achieving the planned alignment, poor correlation of intraoperative data to long-term functional outcomes and implant survivorship, and a paucity of studies on the safe ranges of limb alignment. Further studies on alignment in TKA should use surgical adjuncts (e.g. robotic technology) to help execute the planned alignment with improved accuracy, include intraoperative assessments of knee biomechanics and periarticular soft-tissue tension, and correlate alignment to long-term functional outcomes and survivorship.

Rotating hinge implants are commonly used in revision total knee arthroplasty (TKA) in the setting of significant ligamentous instability or bone deficiency. These highly constrained implants have been associated with variable clinical outcomes and uncertain long-term survivorship. The aim of this study is to establish long-term functional outcomes, radiographic results, and survivorship after revision TKA with a rotating hinge implant.This is a retrospective study of prospectively collected data of 41 consecutive patients undergoing revision TKA with rotating hinge components and minimum 10-years follow-up. The study included 22 females (53.7%) and 19 males (46.3%) with a mean age of 66.6 ± 8.5 years. Clinical outcomes recorded included the Oxford Knee Score (OKS) preoperatively and at latest follow-up. Range of motion, implant survivorship, and complications were also recorded. Predefined radiological outcomes were obtained using plain radiographs.There was a significant improvement in OKS after revision TKA with a rotating hinge implant compared to preoperative scores (40.7 ± 4.2 vs. 21.4 ± 4.9 respectively, p 0.001). At latest follow-up, mean range of motion was 111.5° ± 9.3° and mean overall limb alignment was 0.2° ± 2.0° varus. Implant survivorship at minimum 10-year follow-up was 90.2%. Radiographic lucent lines were observed in 14 patients (34.1%).Revision TKA with a rotating hinge implant leads to satisfactory clinical outcomes and very good implant survivorship at long-term follow-up. Surgeons should have a low threshold to use these versatile implants in complex revision knee arthroplasty.

The use of an extensively porous-coated uncemented cobalt-chrome monoblock femoral stem for revision total hip arthroplasty (THA) is well established with excellent mid-term results. The aim of this study is to report the long-term survivorship of these implants in femoral stem revisions.This is a long-term retrospective review of prospectively collected data of 55 femoral stem revisions in 55 patients using a contemporary, cementless extensively porous-coated cobalt-chrome monoblock stem. All patients between 2001 and 2006 who underwent first time femoral stem revision with a contemporary, cementless extensively porous-coated cobalt-chrome monoblock stem were included. Harris Hip Score, Western Ontario and McMaster Universities Index, and University of California Los Angeles activity scores were recorded preoperatively and at latest follow-up. Radiographs were analyzed for evidence of loosening, subsidence, osteolysis, and bony union. This study included 55 patients, comprising of 36 females (66%) and 19 males (34%) with a mean age of 66.4 ± 9.3 years at the time of surgery. The mean time interval from index procedure was 9.8 ± 2.9 years. Mean time from revision THA to final follow-up was 13.2 ± 2.17 years with a minimum of 10 years of follow-up.Indications for revision included aseptic loosening (33), prosthetic joint infection (13), and periprosthetic fracture (10). Significant improvement in Harris Hip Score (85.1 ± 1.77 vs 51.8 ± 2.3, P.001), Western Ontario and McMaster Universities Index (17.6 ± 0.77 vs 33.3 ± 0.8, P.001), and University of California Los Angeles (5.25 ± 0.2 vs 2.7 ± 0.36, P.001) scores were found at latest follow-up compared to preoperative. Fifty-four patients (98%) achieved stable bony ingrowth on radiographic analysis. All 10 patients treated for periprosthetic fractures achieved bony union of their fractures. Two patients suffered intraoperative periprosthetic fractures and were treated with a cable-plating system. There were no mechanical failures and no femoral stem re-revisions. One patient was diagnosed with a deep infection and was treated with chronic suppressive antibiotic therapy due to significant medical comorbidities.Revision of the femoral component with a contemporary extensively porous-coated cobalt-chrome femoral stem has excellent functional outcomes, radiographic outcomes, and long-term survivorship with minimal complications.

For the first time, mobile campaign and building monitoring experiments were conducted in downtown Seoul, Korea during the 2018/2019 winter period to assess the possibility of the co-benefit of CO2 emission reduction and air quality improvement. Given that CO2 and air pollutants in cities both originate from fossil fuel combustion, monitoring urban CO2 concentrations using a mobile vehicle and from the top of tall buildings can be a potentially effective approach for diagnosing the air quality. The local enhancement values (△species) related to urban emission sources were estimated by eliminating baseline concentrations. The results obtained showed high correlation coefficients between △CO2 and △air pollutants (i.e., 0.753, 0.505, and 0.525 for △CO, △NOX, and △NO2), confirming the applicability of CO2 as an indicator of air pollutant sources in downtown Seoul. The evaluation of the air quality in the study area using air pollutant ratios, including the ratios of CO and NOX/NO2, relative to CO2 showed that the ratios of △CO, △NOX, and △NO2 relative to △CO2 were 5.76, 1.89, and 0.21 ppb ppm−1. The estimated △NO2/△NOX ratio (11%) and a comparison of the △NOX/△CO2 ratios obtained with those reported for other cities in different countries suggested the possibility of a relationship between the current air quality in downtown Seoul and the use of diesel vehicles. Results suggest that the development of municipal policies aimed at mitigating climate change should consider the co-benefit of air quality improvement so as to ensure the effective reduction of CO2 and air pollutant emissions.

The number of patients requiring hip and knee arthroplasty continues to rise each year. Patients are living longer and expecting to remain active into later life following joint replacement. Developments in computer-assisted surgery and robotic technology may optimise surgical outcomes and patient satisfaction following lower limb arthroplasty. The use of artificial intelligence in healthcare is rapidly growing and has gained momentum in lower limb arthroplasty. This article reviews the use of artificial intelligence and surgical innovation in lower limb arthroplasty, with a particular focus on robotic-assisted surgery in total knee arthroplasty.

Injuries to the hamstring muscle complex are common in athletes, accounting for between 12% and 26% of all injuries sustained during sporting activities. Acute hamstring injuries often occur during sports that involve repetitive kicking or high-speed sprinting, such as American football, soccer, rugby, and athletics. They are also common in watersports, including waterskiing and surfing. Hamstring injuries can be career-threatening in elite athletes and are associated with an estimated risk of recurrence in between 14% and 63% of patients. The variability in prognosis and treatment of the different injury patterns highlights the importance of prompt diagnosis with magnetic resonance imaging (MRI) in order to classify injuries accurately and plan the appropriate management.Low-grade hamstring injuries may be treated with nonoperative measures including pain relief, eccentric lengthening exercises, and a graduated return to sport-specific activities. Nonoperative management is associated with highly variable times for convalescence and return to a pre-injury level of sporting function. Nonoperative management of high-grade hamstring injuries is associated with poor return to baseline function, residual muscle weakness and a high-risk of recurrence. Proximal hamstring avulsion injuries, high-grade musculotendinous tears, and chronic injuries with persistent weakness or functional compromise require surgical repair to enable return to a pre-injury level of sporting function and minimize the risk of recurrent injury.This article reviews the optimal diagnostic imaging methods and common classification systems used to guide the treatment of hamstring injuries. In addition, the indications and outcomes for both nonoperative and operative treatment are analyzed to provide an evidence-based management framework for these patients.Cite this article: Bone Joint J 2020;102-B(10):1281–1288.

Aims The safe resumption of elective orthopaedic surgery following the peak of the COVID-19 pandemic remains a significant challenge. A number of institutions have developed a COVID-free pathway for elective surgery patients in order to minimize the risk of viral transmission. The aim of this study is to identify the perioperative viral transmission rate in elective orthopaedic patients following the restart of elective surgery. Methods This is a prospective study of 121 patients who underwent elective orthopaedic procedures through a COVID-free pathway. All patients underwent a 14-day period of self-isolation, had a negative COVID-19 test within 72 hours of surgery, and underwent surgery at a COVID-free site. Baseline patient characteristics were recorded including age, American Society of Anaesthesiologists (ASA) grade, body mass index (BMI), procedure, and admission type. Patients were contacted 14 days following discharge to determine if they had had a positive COVID-19 test (COVID-confirmed) or developed symptoms consistent with COVID-19 (COVID-19-presumed). Results The study included 74 females (61.2%) and 47 males (38.8%) with a mean age of 52.3 years ± 17.6 years (18 to 83 years). The ASA grade was grade I in 26 patients (21.5%), grade II in 70 patients (57.9%), grade III in 24 patients (19.8%), and grade IV in one patient (0.8%). A total of 18 patients (14.9%) had underlying cardiovascular disease, 17 (14.0%) had pulmonary disease, and eight (6.6%) had diabetes mellitus. No patients (0%) had a positive COVID-19 test in the postoperative period. One patient (0.8%) developed anosmia postoperatively without respiratory symptoms or a fever. The patient did not undergo a COVID-19 test and self-isolated for seven days. Her symptoms resolved within a few days. Conclusion The development of a COVID-free pathway for elective orthopaedic patients results in very low viral transmission rates. While both surgeons and patients should remain vigilant, elective surgery can be safely restarted using dedicated pathways and procedures. Cite this article: Bone Joint Open 2020;1-9:562–567.

Road safety performance varies among local municipalities since road safety involves multiple inputs (e.g. facilities and programs) and multiple outputs (e.g. crashes and casualties). A benchmark analysis between local governments is a useful platform to improve their road safety performances because the analysis can specify which other municipalities' processes should be consulted to improve their practices. This study employs the data envelopment analysis approach for benchmark analysis. The input-oriented variable returns to scale model is applied to Korea. The outputs are the numbers of crashes and fatalities, and two sets of indexed inputs comprising institutional managements and governmental interventions are visited. In particular, standardized data formatting between, and controllability by, local governments are highlighted as the required properties for inputs. The overall efficiency scores and the nature of returns to scale reveal the under-investments in road safety in Korea. Efficiency scores by each municipality are also provided. This examination shows the projected values of inputs and outputs as well as benchmarks for each municipality. A sensitivity analysis based on the leave-one-out method generates stable efficiency scores across local governments, which shows the robustness of the model. Finally, the incorporation of environmental variables and dynamic analysis is suggested for further studies.

To determine whether a mobile app can reduce the need for in-person visits and examine the resulting societal cost differences between mobile and conventional follow-up for postoperative anterior cruciate ligament (ACL) reconstruction patients.Study design was a single-center, 2-arm parallel group randomized controlled trial. All patients undergoing ACL reconstruction aged 16 to 70 years were screened for inclusion in the study. Competent use of a mobile device and ability to communicate in English was required. Patients were randomly assigned to receive follow-up via a mobile app or conventional appointments. Analysis was intention-to-treat. The primary outcome was the number of in-person visits to any health care professional during the first 6 postoperative weeks. Secondary outcomes included analysis of costs incurred by the health care system and personal patient costs related to both methods of follow-up. Patient-reported satisfaction and convenience scores, rates of complications, and clinical outcomes were also analyzed.Sixty patients were analyzed. Participants in the app group attended a mean of 0.36 in-person visits versus 2.44 in-person visits in the conventional group (95% confidence interval 0.08-0.28; P.0001). On average, patients in the app group spent $211 (Canadian dollars) less than the conventional group over 6 weeks (P.0001) on personal costs related to follow-up. Health care system costs were also significantly less in the app group ($157.5 vs CAD $202.2; P.0001). There was no difference between groups in patient satisfaction, convenience, complication rates, or clinical outcome measures.Mobile follow-up can eliminate a significant number of in-person visits during the first 6 postoperative weeks in patients undergoing ACL reconstruction with cost savings to both the patient and health care system. This method should be considered for dissemination among similar orthopaedic procedures during early postoperative care.I: Prospective randomized controlled trial.

The coronavirus 2019 (COVID-19) global pandemic has had a significant impact on trauma and orthopaedic (T&O) departments worldwide. To manage the peak of the epidemic, orthopaedic staff were redeployed to frontline medical care; these roles included managing minor injury units, forming a “proning” team, and assisting in the intensive care unit (ICU). In addition, outpatient clinics were restructured to facilitate virtual consultations, elective procedures were cancelled, and inpatient hospital admissions minimized to reduce nosocomial COVID-19 infections. Urgent operations for fractures, infection and tumours went ahead but required strict planning to ensure patient safety. Orthopaedic training has also been significantly impacted during this period. This article discusses the impact of COVID-19 on T&O in the UK and highlights key lessons learned that may help to proactively prepare for the next global pandemic. Cite this article: Bone Joint Open 2020;1-7:420–423.

Aims The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA). Methods This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus). Results ACL resection increased the mean extension gap significantly more than the flexion gap in the medial (mean 1.2 mm (SD 1.0) versus mean 0.2 mm (SD 0.7) respectively; p < 0.001) and lateral (mean 1.1 mm (SD 0.9) versus mean 0.2 mm (SD 0.6) respectively; p < 0.001) compartments. The mean gap differences following ACL resection did not create any significant mediolateral soft tissue laxity in extension (gap difference: mean 0.1 mm (SD 2.4); p = 0.89) or flexion (gap difference: mean 0.2 mm (SD 3.1); p = 0.40). ACL resection did not significantly affect maximum knee extension (change in maximum knee extension = mean 0.2° (SD 0.7°); p = 0.23) or fixed flexion deformity (mean 4.2° (SD 3.2°) pre-ACL release versus mean 3.9° (SD 3.7°) post-ACL release; p = 0.61). ACL resection did not significantly affect overall limb alignment (change in alignment = mean 0.2° valgus (SD 1.0° valgus; p = 0.11). Conclusion ACL resection creates flexion-extension mismatch by increasing the extension gap more than the flexion gap. However, gap differences following ACL resection do not create any mediolateral soft tissue laxity in extension or flexion. ACL resection does not affect maximum knee extension or overall limb alignment. Cite this article: Bone Joint J 2020;102-B(4):442–448.

Indian transportation sector faces the severe challenges in the account of the limited expansion of relevant infrastructure, lack of integration among major transport systems like railways and roadways, and multiple institutions deal with these systems with different mandates. Thus the sector needs the multi-pronged approach to address the challenges in sustainable development. To derive such strategies, this paper assesses India’s evolution of transport policies, identifies the gap between demand and supply related infrastructure, and presents good governance framework to deliver, mainly at the national level. Based on secondary data sources, like census of India, relevant ministries documents, and existing policies and programs, this study reveals that Indian transport system is in the emerging state and it requires demand-based policies to improve overall transport quality in India. This paper concludes with policy recommendations for guiding sustainable transportation system in India.

Metal-on-metal (MoM) arthroplasty systems became popular in the early-2000s due to presumed advantages of improved wear characteristics and superior stability. However, subsequent reports of abnormal soft-tissue reactions to MoM implants and national registry data reporting high failure rates raised concerns. Early outcomes of revision total hip arthroplasty (THA) for adverse reaction to metal debris (ARMD) were poor, leading to development of surveillance programs and a trend towards early revision surgery. Patients with MoM arthroplasties require surveillance, comprehensive history and physical examination, imaging with ultrasound or magnetic resonance imaging (MRI), and laboratory evaluation including metal ion levels. Operative strategies for revision THA vary from exchange of modular components to extensive debridement and reconstruction with revision components. Surgeons should be aware of the increased risks of dislocation and infection following revision THA for ARMD. However, there is growing evidence that early revision surgery prior to extensive soft tissue destruction results in improved outcomes and decreased re-operation rates. It is estimated that >1 million MoM articulations have been implanted, with a large proportion still in situ. It is imperative to understand the aetiology, presentation, and management strategies for these patients to optimise their clinical outcomes.

Ulaanbaatar is the capital and the biggest city of Mongolia. There has been rapid urbanization since 1990. Due to the rapid growth in population and vehicles, traffic congestion has rapidly intensified too. To mitigate the traffic congestion, uses of public transportation is strongly recommended, but the quality of public transportation is not meeting the expectations of Mongolian citizens. In this paper, the analytic hierarchy process (AHP) has been employed to identify priority attributes of Ulaanbaatar bus services. A survey was conducted for a total of 30 people including Mongolian experts and citizens and Korean experts. Results reveal that Ulaanbaatar bus service is unsafe and the bus route is inefficient. In the short term, safety and security attributes should be complemented and, in the long term, convenience and comfort for public transportation commuters should be prioritized in Ulaanbaatar.

Road traffic makes a major contribution to air pollution by emitting solid and liquid particles, also known as particulate matter, into the air. However, the causal relationship between road traffic and particulate matter emissions has not been adequately explored, primarily because traffic is the result of dynamic interactions involving many real-time variables, such as volume and speed. This study used structural equation modeling to quantify this complex causal relationship. A one-year survey using a mobile laboratory was conducted to collect data on particulate matter concentrations and traffic, which were then combined with weather statistics provided by the Korea Meteorological Administration. The key finding of this study suggests that greater attention in research and policy should be directed toward non-exhaust particulate matter emissions from road traffic.

Excess commuting refers to wasteful journey-to-work travel, resulting from the non-optimal spatial configuration of residences and workplaces. Traditionally, this concept has been employed to analy...

Pedestrian crosswalks are not always placed at optimal locations, and some crosswalks cause walkers to detour from their shortest routes. Some walkers run the risk of jaywalking to avoid d...

Traditionally, the performance of transit service has been assessed using the framework of level of service or quality of service. This study proposes a novel platform for evaluating perfor...

Coronavirus disease 2019 (COVID-19) was declared a pandemic by the World Health Organization on March 11, 2020. By mid-March, London had emerged as the epicenter in the United Kingdom, accounting for 45% of the COVID-19-related mortality. A cancer COVID-19-free "cold hub," through National Health Service partnership with independent institutions, was established to maintain a throughput of surgical oncology patients with an accessible triage system for oncologic specialties. The high population density, commuter volume, and rising COVID-19 incidence heightened the challenge of segregating a vulnerable population that was already at high risk for surgical morbidity and mortality.The aim of this review is to report the experience of developing a multicenter COVID-19-free cold hub with the aim of providing safe surgery for surgical oncology patients. We discuss the timeline, structure, and infection control policy and suggest practical points that may guide other health care systems.The surgical oncology hub treated 1542 patients between March 1 and July 1, 2020. There were no cases of COVID-19-related mortality in a 30-day follow-up. Key strategies for the restructuring of the cancer service included the following: (1) formation of an accessible referral pathway, (2) creation and structuring of cold hub hospitals, (3) development of protocols for infection control and preoperative testing, (4) rapid reorganization of services based on initial feedback, and (5) clear communication and leadership.It has been shown that a surgical oncology cold hub with an accessible referral system and an effective system of preoperative screening system can minimize COVID-19 transmission, morbidity, and mortality, in a region with heavy disease prevalence. This structure represents a safe, ethical, and viable system that can be replicated in other health care systems.

Aims Graft infection following anterior cruciate ligament reconstruction (ACLR) may lead to septic arthritis requiring multiple irrigation and debridement procedures, staged revision operations, and prolonged courses of antibiotics. To our knowledge, there are no previous studies reporting on how gentamicin pre-soaking of hamstring grafts influences infection rates following ACLR. We set out to examine this in our study accordingly. Methods This retrospective study included 2,000 patients (1,156 males and 844 females) who underwent primary ACLR with hamstring autografts between 2007 to 2017. This included 1,063 patients who received pre-soaked saline hamstring grafts for ACLR followed by 937 patients who received pre-soaked gentamicin hamstring grafts for ACLR. All operative procedures were completed by a single surgeon using a standardized surgical technique. Medical notes were reviewed and data relating to the following outcomes recorded: postoperative infection, clinical progress, causative organisms, management received, and outcomes. Results Superficial wound infection developed in 14 patients (1.31 %) receiving pre-saline soaked hamstring grafts compared to 13 patients (1.38 %) receiving pre-gentamicin soaked hamstring grafts, and this finding was not statistically significant (p = 0.692). All superficial wound infections were treated with oral antibiotics with no further complications. There were no recorded cases of septic arthritis in patients receiving pre-gentamicin soaked grafts compared to nine patients (0.85%) receiving pre-saline soaked grafts, which was statistically significant (p = 0.004). Conclusion Pre-soaking hamstring autographs in gentamicin does not affect superficial infection rates but does reduce deep intra-articular infection rates compared to pre-soaking hamstring grafts in saline alone. These findings suggest that pre-soaking hamstring autografts in gentamicin provides an effective surgical technique for reducing intra-articular infection rates following ACLR. Cite this article: Bone Jt Open 2021;2(1):66–71.

Aims Echocardiography is commonly used in hip fracture patients to evaluate perioperative cardiac risk. However, echocardiography that delays surgical repair may be harmful. The objective of this study was to compare surgical wait times, mortality, length of stay (LOS), and healthcare costs for similar hip fracture patients evaluated with and without preoperative echocardiograms. Methods A population-based, matched cohort study of all hip fracture patients (aged over 45 years) in Ontario, Canada between 2009 and 2014 was conducted. The primary exposure was preoperative echocardiography (occurring between hospital admission and surgery). Mortality rates, surgical wait times, postoperative LOS, and medical costs (expressed as 2013$ CAN) up to one year postoperatively were assessed after propensity-score matching. Results A total of 2,354 of 42,230 (5.6%) eligible hip fracture patients received a preoperative echocardiogram during the study period. Echocardiography ordering practices varied among hospitals, ranging from 0% to 23.0% of hip fracture patients at different hospital sites. After successfully matching 2,298 (97.6%) patients, echocardiography was associated with significantly increased risks of mortality at 90 days (20.1% vs 16.8%; p = 0.004) and one year (32.9% vs 27.8%; p < 0.001), but not at 30 days (11.4% vs 9.8%; p = 0.084). Patients with echocardiography also had a mean increased delay from presentation to surgery (68.80 hours (SD 44.23) vs 39.69 hours (SD 27.09); p < 0.001), total LOS (19.49 days (SD 25.39) vs 15.94 days (SD 22.48); p < 0.001), and total healthcare costs at one year ($51,714.69 (SD 54,675.28) vs $41,861.47 (SD 50,854.12); p < 0.001). Conclusion Preoperative echocardiography for hip fracture patients is associated with increased postoperative mortality at 90 days and one year but not at 30 days. Preoperative echocardiography is also associated with increased surgical delay, postoperative LOS, and total healthcare costs at one year. Echocardiography should be considered an urgent test when ordered to prevent additional surgical delay. Cite this article: Bone Joint J 2021;103-B(2):271–278.

Aims Total knee arthroplasty (TKA) using functional alignment aims to implant the components with minimal compromise of the soft-tissue envelope by restoring the plane and obliquity of the non-arthritic joint. The objective of this study was to determine the effect of TKA with functional alignment on mediolateral soft-tissue balance as assessed using intraoperative sensor-guided technology. Methods This prospective study included 30 consecutive patients undergoing robotic-assisted TKA using the Stryker PS Triathlon implant with functional alignment. Intraoperative soft-tissue balance was assessed using sensor-guided technology after definitive component implantation; soft-tissue balance was defined as intercompartmental pressure difference (ICPD) of < 15 psi. Medial and lateral compartment pressures were recorded at 10°, 45°, and 90° of knee flexion. This study included 18 females (60%) and 12 males (40%) with a mean age of 65.2 years (SD 9.3). Mean preoperative hip-knee-ankle deformity was 6.3° varus (SD 2.7°). Results TKA with functional alignment achieved balanced medial and lateral compartment pressures at 10° (25.0 psi (SD 6.1) vs 23.1 psi (SD 6.7), respectively; p = 0.140), 45° (21.4 psi (SD 5.9) vs 20.6 psi (SD 5.9), respectively; p = 0.510), and 90° (21.2 psi (SD 7.1) vs 21.6 psi (SD 9.0), respectively; p = 0.800) of knee flexion. Mean ICPD was 6.1 psi (SD 4.5; 0 to 14) at 10°, 5.4 psi (SD 3.9; 0 to 12) at 45°, and 4.9 psi (SD 4.45; 0 to 15) at 90° of knee flexion. Mean postoperative limb alignment was 2.2° varus (SD 1.0°). Conclusion TKA using the functional alignment achieves balanced mediolateral soft-tissue tension through the arc of knee flexion as assessed using intraoperative pressure-sensor technology. Further clinical trials are required to determine if TKA with functional alignment translates to improvements in patient satisfaction and outcomes compared to conventional alignment techniques. Cite this article: Bone Joint J 2021;103-B(3):507–514.

Background:Surgical repair of proximal rectus femoris avulsion injuries is associated with prolonged periods of rehabilitation and highly variable risk of injury recurrence. Surgical tenodesis of these injuries is often reserved for recurrent injuries or revision surgery. To our knowledge, the outcomes of proximal rectus femoris avulsion injuries treated with surgical repair versus primary tenodesis have not been previously reported.Hypothesis:Primary tenodesis of proximal rectus femoris avulsion injuries is associated with reduced risk of injury recurrence as compared with surgical repair.Study Design:Cohort study; Level of evidence, 3.Methods:This study included 25 patients (22 male and 3 female) who underwent surgical repair versus 30 patients (26 male and 4 female) who received primary tenodesis for proximal rectus femoris avulsion injuries. Predefined outcomes were recorded at regular intervals after surgery. Mean follow-up time was 27.9 months (range, 24.0-31.7 months) from date of surgery.Results:All patients returned to their preinjury levels of sporting activity. Primary tenodesis was associated with earlier return to preinjury level of sporting function as compared with surgical repair (mean ± SD, 12.4 ± 1.6 vs 15.8 ± 2.2 weeks; P < .001) and reduced risk of recurrence (0% vs 16%; P < .001). At 1-year follow-up, there was no difference in surgical repair versus primary tenodesis relating to patient satisfaction scores (12 very satisfied and 13 satisfied vs 16 very satisfied and 14 satisfied; P = .70), isometric quadriceps strength (95.6% ± 2.8% vs 95.2% ± 6.3%; P = .31), Tegner scores (median [interquartile range], 9 [8-9] vs 9 [8-9]; P = .54), and lower extremity functional scores (73 [72-76] vs 74 [72-75]; P = .41). High patient satisfaction, quadriceps muscle strength, and functional outcome scores were maintained and remained comparable between treatment groups at 2-year follow-up.Conclusion:Primary tenodesis was associated with reduced time for return to preinjury level of sporting function and decreased risk of injury recurrence when compared with surgical repair for proximal rectus femoris avulsion injuries. There were no differences in patient satisfaction, functional outcome scores, and quadriceps muscle strength between the treatment groups at 1- and 2-year follow-up.

Injuries to the quadriceps muscle group are commonly seen in sporting activities that involve repetitive kicking and high-speed sprinting, including football (soccer), rugby and athletics. The proximal rectus femoris is prone to avulsion injuries as rapid eccentric muscle contraction leads to asynchronous muscle activation and different force vectors through the straight and reflected heads. Risk factors for injury include previous rectus femoris muscle or hamstring injury, reduced flexibility of the quadriceps complex, injury to the dominant leg, and dry field playing conditions. Magnetic resonance imaging (MRI) is the preferred imaging modality as it enables the site of injury to be accurately located, concurrent injuries to be identified, preoperative grading of the injury, and aids surgical planning. Non-operative management is associated with highly variable periods of convalescence, poor return to preinjury level of function and high risk of injury recurrence. Operative treatment of proximal rectus femoris avulsion injuries with surgical repair or surgical tenodesis enables return to preinjury level of sporting activity and high functional outcomes. Surgical tenodesis of proximal rectus femoris avulsion injuries may offer an avenue for further reducing recurrence rates compared to direct suture anchor repair of these injuries. Cite this article: EFORT Open Rev 2020;5:828-834. DOI: 10.1302/2058-5241.5.200055

Background The medial-pivot (MP) design for total knee arthroplasty (TKA) aims to restore more natural “ball-and-socket” knee kinematics compared to the traditional posterior-stabilized (PS) implants for TKA. The objective of this study is to determine if there was any difference in functional outcomes between patients undergoing MP-TKA vs PS-TKA. Methods This prospective randomized controlled trial consisted of 43 patients undergoing MP-TKA vs 45 patients receiving a single-radius PS-TKA design. The primary outcome was postoperative range of motion (ROM). Secondary outcomes included the Western Ontario and McMaster Universities Arthritis Index, Oxford Knee Score, Knee Society Score (KSS), and radiological outcomes. All study patients were followed-up for 2 years after surgery. Results Patients undergoing MP-TKA had comparable ROM at 1 year (114.6° ± 16.3° vs 111.3° ± 17.8° respectively, P = .88) and 2 years after surgery (114.9° ± 15.5° vs 114.9° ± 16.4° respectively, P = .92) compared to PS-TKA. There were also no differences in Western Ontario and McMaster Universities Arthritis Index (26.8 ± 19.84 vs 22.0 ± 12.03 respectively, P = .14), Oxford Knee Score (42.7 ± 8.1 vs 42.3 ± 6.7 respectively, P = .18), KSS clinical scores (82.9 ± 16.96 vs 81.42 ± 10.45 respectively, P = .12) and KSS functional scores (76.2 ± 18.81 vs 73.93 ± 8.53 respectively, P = .62) at 2-year follow-up. There was no difference in postoperative limb alignment or complications. Conclusion This study demonstrated excellent results in both the single-radius PS-TKA design and MP-TKA design. No differences were identified at 2-year follow-up with respect to postoperative ROM and patient-reported outcome measures.

The objectives of this study were to assess the effect of anterior cruciate ligament (ACL) resection on flexion-extension gaps, mediolateral soft tissue laxity, maximum knee extension, and limb alignment during primary total knee arthroplasty (TKA).This prospective study included 140 patients with symptomatic knee osteoarthritis undergoing primary robotic-arm assisted TKA. All operative procedures were performed by a single surgeon using a standard medial parapatellar approach. Optical motion capture technology with fixed femoral and tibial registration pins was used to assess study outcomes pre- and post-ACL resection with knee extension and 90° knee flexion. This study included 76 males (54.3%) and 64 females (45.7%) with a mean age of 64.1 years (SD 6.8) at time of surgery. Mean preoperative hip-knee-ankle deformity was 6.1° varus (SD 4.6° varus).ACL resection increased the mean extension gap significantly more than the flexion gap in the medial (mean 1.2 mm (SD 1.0) versus mean 0.2 mm (SD 0.7) respectively; p0.001) and lateral (mean 1.1 mm (SD 0.9) versus mean 0.2 mm (SD 0.6) respectively; p0.001) compartments. The mean gap differences following ACL resection did not create any significant mediolateral soft tissue laxity in extension (gap difference: mean 0.1 mm (SD 2.4); p = 0.89) or flexion (gap difference: mean 0.2 mm (SD 3.1); p = 0.40). ACL resection did not significantly affect maximum knee extension (change in maximum knee extension = mean 0.2° (SD 0.7°); p = 0.23) or fixed flexion deformity (mean 4.2° (SD 3.2°) pre-ACL release versus mean 3.9° (SD 3.7°) post-ACL release; p = 0.61). ACL resection did not significantly affect overall limb alignment (change in alignment = mean 0.2° valgus (SD 1.0° valgus; p = 0.11).ACL resection creates flexion-extension mismatch by increasing the extension gap more than the flexion gap. However, gap differences following ACL resection do not create any mediolateral soft tissue laxity in extension or flexion. ACL resection does not affect maximum knee extension or overall limb alignment. Cite this article

Background: Surgical repair of proximal hamstring avulsion injuries can enable the return to preinjury levels of sporting function and minimize the risk of recurrence in both professional and recreational athletes. While venous thromboembolism (VTE) is a recognized complication of surgical repair, the incidence thereof is poorly reported in the literature. Purpose/Hypothesis: To report the incidence of symptomatic VTE after proximal hamstring avulsion repair and assess the efficacy of our thromboprophylaxis protocol. It was hypothesized that the incidence of VTE after proximal hamstring avulsion repair is low and that aspirin is an adequate choice of chemical prophylaxis. Study Design: Cohort study; Level of evidence, 2. Methods: We performed a prospective cohort study of 2 groups of patients who underwent proximal hamstring avulsion (partial and complete) repair between 2000 to 2020 with different thromboprophylaxis protocols. No patients were routinely screened for VTEs, and VTE was investigated only if clinically indicated. Prospectively collected data included demographics, the mechanism and sport that caused injury, use of bracing, and clinical diagnosis of deep vein thrombosis (DVT) or pulmonary embolism (PE). The first cohort (n = 380) was given mechanical prophylaxis in the form of compression stockings for 6 weeks postoperatively. The second cohort (n = 600) was given compression stockings and aspirin 150 mg once daily routinely, or prophylactic low–molecular weight heparin in high-risk individuals, until the 6-week follow-up. Patients in both cohorts underwent early mobilization after surgery; a hinged knee brace locked at 60° to 120° was provided if the tendon repair was under significant tension. The surgical technique and rehabilitation protocol remained consistent throughout the study. Results: The overall incidence of symptomatic VTE was 0.51%. A total of 5 patients developed symptomatic VTEs (3 DVTs, 2 PEs) in the first cohort, and no patients developed symptomatic VTEs in the second cohort (1.32% vs 0%; P = .0048). Conclusion: The incidence of symptomatic VTE after proximal hamstring avulsion repairs was extremely low. A combination of aspirin, early mobilization despite bracing, compression stockings, and good hydration was an effective thromboprophylaxis strategy.

This paper investigates the nonuse values for expressways. The values represent travellers’ willingness-to-pay regardless of any direct or indirect uses for the transport facility. Option, vicariou...

There have been extensive studies on the monetary valuations for the transit service attributes such as fares, frequency, and in- and out-of-vehicle time. On the contrary, five categories of the elements relating to tangible, comfort, convenience, customer care, and safety and security have not been sufficiently evaluated. This paper explored the valuations based on the service improvements of Korean high-speed rail. The survey for attribute selection identified 11 user-tailored items for the betterment. Factors pertinent to comfort were predominantly preferred. Subsequently, choice experiments were conducted in the form of train-type choices. Binary logit models were then specified and estimated using the data collected. Monetary values were obtained in both individual attributes and a service bundle. Policy implications were also investigated in terms of price discriminations. The direction for future studies, particularly in examining user heterogeneity, was finally suggested.

BackgroundThe process of obtaining informed consent is an important and complex pursuit, especially within a paediatric setting. Medical governing bodies have stated that the role of the trainee surgeon must be explained to patients and their families during the consent process. Despite this, attitudes and practices of surgeons and their trainees regarding disclosure of the trainee’s participation during the consent process has not been reported in the paediatric setting.MethodsNineteen face-to-face interviews were conducted with surgical trainees and staff surgeons at a tertiary-level paediatric hospital in Toronto, Canada. These were transcribed and subsequently thematically coded by three reviewers.ResultsFive main themes were identified from the interviews. (1) Surgeons do not consistently disclose the role of surgical trainees to parents. (2) Surgical trainees are purposefully vague in disclosing their role during the consent discussion without being misleading. (3) Surgeons and surgical trainees believe parents do not fully understand the specific role of surgical trainees. (4) Graduated responsibility is an important aspect of training surgeons. (5) Surgeons feel a responsibility towards both their patients and their trainees. Surgeons do not explicitly inform patients about trainees, believing there is a lack of understanding of the training process. Trainees believe families likely underestimate their role and keep information purposely vague to reduce anxiety.ConclusionThe majority of surgeons and surgical trainees do not voluntarily disclose the degree of trainee participation in surgery during the informed consent discussion with parents. An open and honest discussion should occur, allowing for parents to make an informed decision regarding their child’s care. Further patient education regarding trainees’ roles would help develop a more thorough and patient-centred informed consent process.

As Korea is predicted to be a super-aged society in the near future, transport policies that internalize the elderly have also drawn attentions. Even though some studies have examined the travel by the elderly with various motives, it is, however, difficult to find references that deal with the unique spatio-temporal characteristics of senior trips. For example, the models by time period have represented the temporal property while a set of independent variables associated with urban infrastructure have addressed the spatial feature. This study was conducted under a trip attraction model for transit. The result shows that transit facilities, commercial areas, and hospitals are the dominant factors to explain the travel by the elderly, particularly during 09:00-17:00. Keywords regression model; smart card data; trip attraction model; the elderly; urban infrastructure ; 회귀모형; 교통카드자료; 통행유입 모형; 고령자; 도시기반시설 Language: ko

교통량 배정 알고리즘은 통행자가 어느 경로를 이용하는 지를 분석하는 기법으로 전통적 교통수요 예측과정의 네 번 째 단계에 적용된다. 이 단계에서 예측된 통행저항은 다시 교통수요 예측과정의 다른 단계에 입력자료로 사용된다. 예 컨대, 경로의 통행저항은 주거지 선택(통행발생), 통행분포, 교통수단 선택 모형에서 중요한 독립변수이다. 이는 교통량 배정 알고리즘의 정확도가 교통수요 예측의 모든 과정에 상 당한 영향을 미칠 수 있음을 의미한다. 또한 재난상황에 대 한 네트워크의 취약성 분석이나 수도권 광역·도시철도 운 영기관간 운임수입 정산 등의 응용분야에서도 교통량 배정 알고리즘의 정확도에 대한 요구가 높다. 이에 따라 교통량 배정 알고리즘의 적합성 평가가 주목 받 고 있으며, 최근에는 대중교통 교통량 배정 알고리즘에 대 한 평가도 일부 시도되었다. 예컨대, Liu et al. [1]은 대중 교통 교통량 배정 알고리즘을 정태적 교통량 배정 기법(전 량 배정기법, 확률적 경로선택 모형, 이용자 균형 기법), 동 태적 교통량 배정 기법 등으로 분류하고 각 알고리즘의 특 성을 이론적 측면에서 광범위하게 고찰하였다. 또한 Kato et al. [2]는 동경 대도시권의 도시철도망을 대상으로 다항 로 짓 모형, 구조화된 다항 프로빗 모형, 이용자균형 기법, 로 짓기반 확률적 이용자균형 기법, 프로빗기반 확률적 이용자 균형 기법, 전량 배정기법 등 6개 알고리즘의 성능(performance)을 평가하였다. 그러나 국내 학계에서는 교통량 배정 알고리즘의 적합성 과 발전방향에 대한 논의가 활발하지 않다. 특히 도시철도 부문 교통량 배정은 지난 십여 년 동안 최적전략 알고리즘 (the Optimal strategy algorithm)이 표준적으로 적용되고 있 으나, 이 알고리즘이 도시철도 이용자의 통행행태 분석에 적 합한지에 대한 연구는 충분하지 않다. 이에 본 연구는 최적 전략 알고리즘을 포함하여 경로선택 알고리즘, Dial 알고리 Abstract This paper evaluates the performance of transit assignment algorithms for urban rail networks. The accuracy of the algorithms is essential not just for travel forecasting but also for the area of applications such as the assessment of road vulnerability and the fare adjustments between train operating companies. Nonetheless, the suitability and caveats for the series of computational steps have not yet been much discussed. This study thus considers the characteristics that are appropriate for investigating Seoul rail travelers using three representative transit assignment algorithms: the optimal strategy algorithm, route choice algorithms, and the Dial’s algorithm. Both the theoretical foundation and the empirical performance are examined. The results demonstrate that the Dial’s algorithm is superior in terms of the theoretical soundness and the computational efficiency.

Pigmented villonodular synovitis (PVNS) is a benign aggressive disease that presents in either a localized (LPVNS) or diffuse (DPVNS) form. Arthroscopic synovectomy is the standard operative treatment for LPVNS, and when used to treat DPVNS, it is usually combined with an open posterior procedure. The purpose of this Technical Note is to report the technique that we have refined to allow for arthroscopic synovectomy as the sole treatment for DPVNS. We describe our technique with the factors we have found to be important to ensure adequate arthroscopic synovectomy, while minimizing risks and complications. The combination of additional portals, the use of multiple different shavers and arthroscopes, and the use of a leg holder all maximize our ability to clear disease.

As ground transport infrastructure causes diverse externalities such as noise and urban separation, the rerouting of such facilities to tunnels is one practical option to resolve the problem of social costs. Although such a mega-project is normally associated with huge budgets, this solution can also generate useful benefits for society. This paper explores these benefits using the Yongsan line in Seoul, Korea, as a case study. Four representative values are considered. Noise reduction benefits are represented by two cost components: annoyance and health risk. Railway crossings are evaluated by operating and accident costs. Excess travel time for pedestrians is used as the key index to measure urban separation. Finally, the value of the landscape is quantified based on an anthropocentric method in the form of the transfer of benefits. In the calculation of these benefits, the local parameters of Korea are applied for realistic estimates while a universal methodology for each component is adopted for secur...

This paper assessed the weights of attributes in creating transit malls. The aim of the creation was classified as travel demand management and urban revitalization. The attributes were grouped into four aspects, or 4As: attraction, amenity, accessibility, and activity. These dimensions represented land-use, urban design, transport, and socio-cultural characteristics, respectively. The analytical hierarchy process was applied to explore the weights. Accessibility(52.7%), attraction(25.6%), amenity(13.7%), and activity(8.0%) were the order of magnitude in weights for the purpose of travel demand management, while attraction(36.1%), accessibility(30.6%), amenity(17.7%), and activity(15.6%) were that of urban revitalization. The multi criteria analysis also showed different size of weights in the sub planning attributes. These results indicate that the aimin implementingtransit malls should be differentiated and highlight that the combined land-use and transport plan is essential for the successful development. Car accessibility and socio-cultural characteristics are also understood as the important factors.이 연구는 대중교통전용지구의 조성목적에 따른 계획요소별 중요도 평가에 관한 것이다 . 대중교통전용지구의 조성목적은 교통수요관리형과 지역활성화추진형으로 구분하였다 . 이를 바탕으로 계획요소를 토지이용 , 도시설계, 교통, 사회문화 특성으로 분류하고 이를 4As(Attraction, Amenity, Accessibility, Activity)라 명명하였다. AHP(Analytical Hierarchy Process) 기법을 통해 각 조성목적별로 계획요소의 중요도를 평가한 결과 , 교통수요관리형은 교통(52.7%), 토지이용(25.6%), 도시설계(13.7%), 사회문화(8.0%) 순으로, 지역활성화추진형은 토지이용(36.1%), 교통(30.6%), 도시설계(17.7%), 사회문화(15.6%) 순으로 도출되었다. 또한, 조성목적별로 세부계획요소의 중요도에서도 차이가 나타났다. 이러한 결과는 대중교통전용지구의 조성목적을 구분할 필요가 있음을 뒷받침하며 , 다양한 계획요소의 반영을 위해서는 교통부문 단독계획이 아닌 타 계획과의 연계가 필수적임을 시사한다 . 또한 승용차 접근성이 배제요인이 아닌 선택요인이라는 것과 사회문화적 특성에 대한 고려도 필요함을 확인하였다 .

This paper compares the performance of trip generation models. Trip generation estimates the number of trips to and from a traffic analysis zone. This process is the first stage of the conventional four-step travel forecasting framework. Although many approaches have been suggested for this step, regression and category analyses have been widely applied. The two methods have generated an acceptable level of performance from the perspective of transport planning. Critical problems, however, have also been observed. In the regression analysis, trip rates are treated as continuous variables that can be negative, which is obviously unrealistic. Furthermore, the method does not incorporate traveler behavior. For the category analysis, its arbitrary way of choosing independent variables and their strata has drawn critiques. The cell-by-cell calculation in this method also increases the concerns about unreliable estimation of trip rates. Censored regression, count data, and discrete choice models have been visited for the alternative of regression approach while the multiple classification method has been conceived for the substitute of the category analysis. A systematic examination of the performance among the models has not been discussed sufficiently yet, which is the motive of this paper. Six representative models – regression, tobit, Poisson, ordered logit, category, and multiple classification analyses – were applied to the homebased work trips in the Seoul metropolitan area. Cross-validation and back-casting were the key for checking the performance among the models. In this process, the measures of correlation, variance, and coincidence were compared. The category-type model was superior in overall performance.

The paper offers a valuation of urban rail noise in South Korea using the hedonic pricing method. It considers trade-offs in the context of housing prices, locality, and environment intrusion. The model adopted provides a reasonable explanation of the determinants of property values, with a unit increase in dB(A) decreases property value by 0.53% in the Seoul area.

The total economic value for a transportation service consists of use, option, and non-use value. The use benefit is based on a traveler’s willingness to pay for usual consumption of the service. The optional value, on the other hand, is related to the possible use of the service for trips not yet anticipated or currently accommodated by other travel modes. The non-use value, however, is derived from the intrinsic merit of the service, even though a trip-maker never actually or potentially depends on the mode. A closed-ended contingent valuation method is considered for the quantification of the option and non-use values. A survey of single- and double-bounded dichotomous choices is conducted with a case study of South Korean bus operations. A logistic regression model and a survival analysis for the single- and double-bounded approaches, respectively, are applied. The estimation result is examined according to the statistical property required and the behavioral validity expected. In particular, three issues from the output are discussed. First, the results help to show the preferable framework between single- and double-bounded surveys for addressing an individual’s option and non-use values. Second, the differences in the absolute values of option and non-use values are compared. Thirdly, the relationship between trip-makers’ willingness to pay and the level of service of their primary travel modes are investigated. In conclusion, the summary of research and the possibilities for future studies are given.

This paper considers a way of assessing travel time reliability in transport appraisal. The term travel time reliability generally refers to variations in journey time that travellers may not predict. Two essential requirements for the evaluation and guidance of the appraisal are discussed. The requirements represent the measurement and valuation of travel time uncertainties. The gap between actual and planned journey times is used for the quantification, subject to the differing characteristics of road and rail usage. A logit-based choice model is developed to derive monetary values of travel time variation. Guidelines are established using the standard framework of the rule of a half. Concluding remarks are also presented.