Aims. The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI). Methods. This is a retrospective cohort study of operatively managed orthopaedic trauma patients from 1 January 2007 to 31 December 2016, performed in Queensland, Australia. Record linkage was used to develop a person-centric, population-based dataset incorporating routinely collected administrative, clinical, and health economic information. The FRI group consisted of patients with International Classification of Disease 10th Revision diagnosis codes for deep infection associated with an implanted device within two years following surgery, while all others were deemed not infected. Demographic and clinical variables, as well as healthcare utilization costs, were compared. Results. There were 111,402 patients operatively managed for orthopaedic trauma, with 2,775 of these (2.5%) complicated by FRI. The development of FRI had a statistically significant association with older age, male sex, residing in rural/remote areas, Aboriginal or Torres Strait Islander background, lower socioeconomic status, road traffic accident, work-related injuries, open fractures, anatomical region (lower limb, spine, pelvis), high injury severity, requiring soft-tissue coverage, and medical comorbidities (univariate analysis). Patients with FRI had an eight-times longer median inpatient length of stay (24 days vs 3 days), and a 2.8-times higher mean estimated inpatient hospitalization cost (AU$56,565 vs AU$19,773) compared with uninfected patients. The total estimated inpatient cost of the FRI cohort to the healthcare system was AU$156.9 million over the ten-year period. Conclusion. The results of this study advocate for improvements in trauma care and infection management, address social determinants of health, and highlight the upside potential to improve prevention and treatment strategies. Cite this article: Bone Joint J 2024;106-B(1):77–85

Total hip arthroplasty (THA) is one of the most successful and effective treatments for advanced hip osteoarthritis (OA). Over the last 5 years, Canada has seen a 17.8% increase in the number of hip replacements performed annually, and that number is expected to grow along with the aging Canadian population. However, the rise in THA surgery is associated with an increased number of patients at risk for the development of an infection involving the joint prosthesis and adjacent deep tissue – periprosthetic joint infections (PJI). Despite improved hygiene protocols and novel surgical strategies, PJI remains a serious complication. No previous population-based studies has investigated PJI risk factors using a time-to-event approach and none have focused exclusively on patients undergoing THA for primary hip OA. The purpose of this study is to determine risk factors for PJI after primary THA for OA using a large population-based database collected over 15 years. Our secondary objective is to determine the incidence of PJI, the time to PJI following primary THA, and if PJI rates have changed in the past 15 years. We performed a population-based cohort study using linked administrative databases in Ontario, Canada in accordance with RECORD and STROBE guidelines. All primary total hip replacements performed for osteoarthritis in patients aged 55 or older between January 1st 2002 – December 31st 2016 in Ontario, Canada were identified. Periprosthetic joint infection as the cause for revision surgery was identified with the International Classification of Diseases, 10th Edition (ICD-10), Clinical Modification diagnosis code T84.53 in any component of the healthcare data set. Data were obtained from the Institute for Clinical Evaluative Sciences (ICES). Demographic data and outcomes are summarized using descriptive statistics. We used a Cox proportional hazards model to analyze the effect of surgical factors and patient factors on the risk of developing PJI. Surgical factors include the approach, use of bone graft, use of cement, and the year of surgery. Patient factors include sex, age at surgery, income quintile and rurality (community vs. urban). We compared the 1,2,5 and 10 year PJI rates for patients undergoing THA each year of our cohort with the Cochran-Armitage test. Less than 0.1% of data were missing from all fields except for rurality which was lacking 0.3% of data. A total of 100,674 patients aged 55 or older received a primary total hip arthroplasty for osteoarthritis from 2002–2016. We identified 1034 cases of revision surgery for prosthetic joint infection for an overall PJI rate of 1.03%. When accounting for patients censored at final follow-up, the cumulative incidence for PJI is 1.44%. Our Cox proportional hazards model revealed that male sex, Type II diabetes mellitus, discharge to convalescent care, and having both hips replaced during one's lifetime were associated with increased risk of developing PJI following primary THA. Importantly, the time adjusted risk for PJI was equal for patients operated within the past 5 years, 6–10 years ago, or 11–15 years ago. The surgical approach, use of bone grafting or cement were not associated with increased risk of infection. PJI rates have not changed significantly over the past 15 years. One, two, five and ten-year PJI rates were similar for patients undergoing THA in all qualifying years. Analysis of a population-based cohort of 100,674 patients has shown that the risk of developing PJI following primary THA has not changed over 15 years. The surgical approach, use of bone grafting or cement were not associated with increased risk of infection. Male sex, Type II diabetes Mellitus and discharge to a rehab facility are associated with increased risk of PJI. As the risk of PJI has not changed in 15 years, an appropriately powered trial is warranted to determine interventions that can improve infection rate after THA

Aims. The aim of this study was to report a complete overview of both incidence, fracture distribution, mode of injury, and patient baseline demographics of paediatric distal forearm fractures to identify age of risk and types of activities leading to injury. Methods. Population-based cohort study with manual review of radiographs and charts. The primary outcome measure was incidence of paediatric distal forearm fractures. The study was based on an average at-risk population of 116,950. A total number of 4,316 patients sustained a distal forearm fracture in the study period. Females accounted for 1,910 of the fractures (44%) and males accounted for 2,406 (56%). Results. The overall incidence of paediatric distal forearm fractures was 738.1/100,000 persons/year (95% confidence interval (CI) 706/100,000 to 770/100,000). Female incidences peaked with an incidence of 1,578.3/100,000 persons/year at age ten years. Male incidence peaked at age 13 years, with an incidence of 1,704.3/100,000 persons/year. The most common fracture type was a greenstick fracture to the radius (48%), and the most common modes of injury were sports and falls from ≤ 1 m. A small year-to-year variation was reported during the five-year study period, but without any trends. Conclusion. Results show that paediatric distal forearm fractures are very common throughout childhood in both sexes, with almost 2% of males aged 13 years sustaining a forearm fracture each year. Cite this article: Bone Jt Open 2022;3(6):448–454

Population-based studies from the United States have reported that sarcoma patients living in rural areas or belonging to lower socioeconomic classes experience worse overall survival; however, the evidence is not clear for universal healthcare systems where financial resources should theoretically not affect access to standard of care. The purpose of this study was to determine the survival outcomes of soft-tissue sarcoma (STS) patients treated in Ontario, Canada over 23 years and determine if the patient's geographic location or income quintile are associated with survival. We performed a population-based cohort study using linked administrative databases of patients diagnosed with STS between 1993 – 2015. The Kaplan-Meier method was used to estimate 2, 5, 10, 15 and 20-year survival stratified by age, stage and location of tumor. We estimated survival outcomes based on the patient's geographic location and income quintile. The Log-Rank test was used to detect significant differences between groups. If groups were significantly different, a Cox proportional hazards model was used to test for interaction effects with other patient variables. We identified 8,896 patients with biopsy-confirmed STS during the 23-year study period. Overall survival following STS diagnosis was 70% at 2 years, 59% at 5 years, 50% at 10 years, 43% at 15 years, and 38% at 20 years. Living in a rural location (p=0.0028) and belonging to the lowest income quintile (p<0.0001) were independently associated with lower overall survival following STS diagnosis. These findings were robust to tests of interaction with each other, age, gender, location of tumor and stage of disease. This population-based cohort study of 8,896 STS patients treated in Ontario, Canada over 23 years reveals that patients living in a rural area and belonging to the lowest income quintile are at risk for decreased survival following STS diagnosis. We extend previous STS survival reporting by providing 15 and 20-year survival outcomes stratified by age, stage, and tumor location

To determine the risk of total knee replacement (TKR) for primary osteoarthritis (OA) associated with overweight/obesity in the Australian population. This population-based study analyzed 191,723 cases of TKR collected by the Australian Orthopaedic Association National Joint Registry and population data from the Australian Bureau of Statistics. The time-trend change in incidence of TKR relating to BMI was assessed between 2015-2018. The influence of obesity on the incidence of TKR in different age and gender groups was determined. The population attributable fraction (PAF) was then calculated to estimate the effect of obesity reduction on TKR incidence. The greatest increase in incidence of TKR was seen in patients from obese class III. The incidence rate ratio for having a TKR for obesity class III was 28.683 at those aged 18-54 years but was 2.029 at those aged >75 years. Females in obesity class III were 1.7 times more likely to undergo TKR compared to similarly classified males. The PAFs of TKR associated with overweight or obesity was 35%, estimating 12,156 cases of TKR attributable to obesity in 2018. The proportion of TKRs could be reduced by 20% if overweight and obese population move down one category. Obesity has resulted in a significant increase in the incidence of TKR in the youngest population in Australia. The impact of obesity is greatest in the young and the female population. Effective strategies to reduce the national obese population could potentially reduce 35% of the TKR, with over 10,000 cases being avoided

The primary objective is to compare revision rates for lumbar disc replacement (LDR) and fusion at the same or adjacent levels in Ontario, Canada. The secondary objectives include acute complications during hospitalization and in 30 days, and length of hospital stay. A population-based cohort study was conducted using health administrative databases including patients undergoing LDR or single level fusion between October 2005 to March 2018. Patients receiving LDR or fusion were identified using physician claims recorded in the Ontario Health Insurance Program database. Additional details of surgical procedure were obtained from the Canadian Institute for Health Information hospital discharge abstract. Primary outcome measured was presence of revision surgery in the lumbar spine defined as operation greater than 30 days from index procedure. Secondary outcomes were immediate/ acute complications within the first 30 days of index operation. A total of 42,024 patients were included. Mean follow up in the LDR and fusion groups were 2943 and 2301 days, respectively. The rates of revision surgery at the same or adjacent levels were 4.7% in the LDR group and 11.1% in the fusion group (P=.003). Multivariate analysis identified risk factors for revision surgery as being female, hypertension, and lower surgeon volume. More patients in the fusion group had dural tears (p<.001), while the LDR group had more “other” complications (p=.037). The LDR group had a longer mean hospital stay (p=.018). In this study population, the LDR group had lower rates of revision compared to the fusion group. Caution is needed in concluding its significance due to lack of clinical variables and possible differences in indications between LDR and posterior decompression and fusion

Introduction:. There is substantial range in kinematics and joint loading in the total knee arthroplasty (TKA) patient population. Prospective TKA designs should be evaluated across the spectrum of loading conditions observed in vivo. Recent research has implanted telemetric tibial trays into TKA patients and measured loads at the tibiofemoral (TF) joint [1]. However, the number of patients for which telemetric data is available is limited and restricts the variability in loading conditions to a small subset of those which may be encountered in vivo. However, there is a substantial amount of fluoroscopic data available from numerous TKA patients and component designs [2]. The purpose of this study was to develop computational simulations which incorporate population-based variability in loading conditions derived from in vivo fluoroscopy, for eventual use in computational as well as experimental activity models. Methods:. Fluoroscopic kinematic data was obtained during squat for several patients with fixed bearing and rotating platform (RP) components. Anterior-posterior (A-P) and internal-external (I-E) motions of the TF joint were extracted from full extension to maximum flexion. Joint compressive loading was estimated using an inverse-dynamics approach. Previously-developed computational models of the knee, lower limb, and Kansas knee simulator were virtually implanted with the same design as the fluoroscopy patients. A control system was integrated with the computational models such that external loading at the hip and ankle were determined in order to reproduce the measured in vivo motions and compressive load (Fig. 1). Accuracy of the model in matching the in vivo motions was assessed, in addition to the resulting joint A-P and I-E loading. The external loading determined for a broader range of patients can subsequently be utilized in a force-controlled simulation to assess the robustness of implant concepts to patient loading variability. The applicability of this work as a comparative tool was illustrated by assessing the kinematics of two PS RP designs under three patient-specific loading conditions. Results:. External hip and ankle loading conditions were determined for each computational model that reproduced in vivo A-P, I-E and flexion-extension joint motions and estimated compressive load. For example, RMS accuracy of 0.4 mm, 0.2° and 0.7° were achieved for A-P, I-E and flexion, respectively (Fig. 1, 2). There was good agreement in both trend and magnitude of joint loads predicted from the externally-loaded models compared to telemetric measurements. Comparative analysis of two designs under multiple loading conditions illustrated variability in joint mechanics as a result of design factors and variation between subjects for the same design (Fig. 3). Discussion:. Pre-clinical evaluation of new devices under physiological joint loading conditions is crucial to robust functionality across the TKA population. The loads applied to a TKA system will affect fixation, wear, and functional performance. Harnessing in vivo kinematic data to develop population-based loading profiles will facilitate development of a platform for comprehensive design-phase evaluation of prospective designs. In addition, loading conditions for experimental simulators can be developed in order to test new devices under the range of variability likely to be encountered in vivo

Bone fixation plates are routinely used in corrective and reconstructive interventions. Design of such implants must take into consideration not only good surface fit, but also reduced intra-operative bending and twisting of the implant itself. This process increases mechanical stresses within the implant and affects its durability and the functional outcome of the surgery. Wound exposure and anaesthesia times are also reduced. Current population-based designs consider the average shape of a target bone as a template to pre-shape the implant. Other studies try to enhance the average design by optimising surface metrics in a statistical shape space. This could ensure a low mean distance between the implant and any bone in the population, but does not reduce neither the maximum possible distances nor directly the mechanical forces needed to fit the implant to the specific patient. We propose a population-based study that considers the bending and torsion forces as metrics to be minimised for the design of enhanced fixation plates. Our aim is to minimise the necessary intra-operative deformations of the plates. In our approach, we first propose to represent a fixation plate by dividing it into discrete sections lengthwise and fitting a plane to each section. The number of sections depends on the size of the implant and anatomical location. It should be small enough to capture the anatomical curvatures, but large enough not to be affected by local noise in the surface. Surface patches corresponding to common locations for plate fixations are extracted from 200 segmented computed tomography (CT) images. In this work, distal lateral femoral patches are considered. A statistical shape model of the patches is then computed and a large population of 2,197 instances is generated, evenly covering the natural statistical variation within the initial population. These instances are considered as both bone surfaces and potential new designs of the contact surface of the fixation plate. The key formulation of our solution is to examine the effect of deforming each section of the implant on the rest of the sections and compute the amount of bending and torsion needed to shape one patch to another. Each instance of the population is fitted to all others and the maximum bending and torsion angles are recorded. A similar process was applied for the mean of the population. The goal is to pick from the population the shape that simultaneously minimises the bending and torsion angles. The maximum required bending was reduced from 25.3® to 19.3® (24.72% reduction), whereas the torsion component was reduced from 12.4® to 6.2® (50% reduction). The method proposed in this abstract enhances the current state-of-the-art in orthopaedic implant design by considering the mechanical deformations applied to the implant during the surgery. The obtained results are promising and indicate a noticeable improvement over the standard pre-contouring to the population mean. We plan to further validate the method and as a future outlook, we intend to test the approach in real surgical scenarios

Since the introduction of national guidelines in 2009 encouraging the use of total hip arthroplasty (THA) to treat intracapsular neck of femur fractures there has been no population-based studies into the surgical outcomes for this indication. This study aims to calculate the complication rates for THA when performed for a fractured neck of femur and compare them to THA performed for primary osteoarthritis in the same population. The Scottish Arthroplasty Project was used to identify all THAs performed in Scotland for neck of femur fracture and osteoarthritis between 1st of January 2009 and 31st December 2014. Dislocation, infection and revision rates at 1 year were calculated. The rate of dislocation, infection and revision at 1 year were all significantly increased among the fracture neck of femur cohort. In total 44046 THAs were performed, 38316 for OA and 2715 for a neck of femur fracture. 2.1% of patients (n=57) who underwent a THA for a neck of femur fracture suffered a dislocation in the 1st year postoperatively, compared to 0.9% (n=337) when the THA was performed for osteoarthritis. Relative Risk of dislocation: 2.3870 (95% C.I. 1.8077–3.1252, p value <0.0001). Relative Risk of infection: 1.4561 (95% C.I. 1.0496–2.0200, p value 0.0245) Relative Risk of revision: 1.4807 (95% C.I. 1.0308–2.1268, p value 0.0336). This is the first time a dislocation rate for THA performed for a neck of femur fracture has been calculated for an entire population. As the number of THAs for neck of femur fracture increases this dislocation rate will have clinical implications

Traumatic disruption of the pelvic ring has a high risk of mortality. These injuries are predominantly due to high-energy, blunt trauma and severe associated injuries are prevalent, increasing management complexity. This population-based study investigated predictors of mortality following severe pelvic ring fractures managed in an organised trauma system. Cases aged greater than 15 years from 1st July 2001 to 30th June 2008 were extracted from the population-based state-wide Victorian State Trauma Registry for analysis. Patient demographic, pre-hospital and admission characteristics were considered as potential predictors of mortality. Multivariate logistic regression was used to identify predictors of mortality with adjusted odds ratios (AOR) and 95% confidence intervals (CI) calculated. There were 348 cases over the 8-year period. The mortality rate was 19%. Patients aged greater than 65 years were at higher odds of mortality (AOR 7.6, 95% CI: 2.8, 20.4) than patients aged 15–34 years. Patients hypotensive at the scene (AOR 5.5, 95% CI: 2.3, 13.2), and on arrival at the definitive hospital of care (AOR 3.7, 955 CI: 1.7, 8.0), were more likely to die than patients without hypotension. The presence of a severe chest injury was associated with an increased odds of mortality (AOR 2.8, 95% CI: 1.3, 6.1), while patients injured in intentional events were also more likely to die than patients involved in unintentional events (AOR 4.9, 95% CI: 1.6, 15.6). There was no association between the hospital of definitive management and mortality after adjustment for other variables, despite differences in the protocols for managing these patients at the major trauma services (Level 1 trauma centres). The findings highlight the importance of the need for effective control of haemodynamic instability for reducing the risk of mortality. As most patients survive these injuries, further research should focus on long term morbidity and the impact of different treatment approaches

Socially deprived patients face significant barriers that reduce their access to care, presenting unique challenges for orthopaedic surgeons. Few studies have investigated the outcomes of surgical fracture care among those socially deprived, despite the increased incidence of fractures, and the inequality of care received in this group. The purpose of this study was to evaluate whether social deprivation impacted the complications and subsequent management of marginalized/homeless patients following ankle fracture surgery. In this retrospective, population-based cohort study involving 202 hospitals in Ontario, Canada, we evaluated 45,444 patients who underwent open reduction internal fixation for an ankle fracture performed by 710 different surgeons between January 1, 1994, and December 31, 2011. Socioeconomic deprivation was measured for each patient according to their residential location by using the “deprivation” component of the Ontario Marginalization Index (ON-MARG). Multivariable logistic regression models were used to assess the relationship between deprivation and shorter-term outcomes within 1 year (implant removal, repeat ORIF, irrigation and debridement due to infection, and amputation). Multivariable cox proportional hazards (CPH) models were used to assess longer-term outcomes up to 20 years (ankle fusion and ankle arthroplasty). A higher level of deprivation was associated with an increased risk of I&D (quintile 5 vs. quintile 1: odds ratio (OR) 2.14, 95% confidence interval (CI), 1.25–3.67, p = 0.0054) and amputation (quintile 4 vs. quintile 1: OR 3.56, 95% CI 1.01–12.4, p = 0.0466). It was more common for less deprived patients to have their hardware removed compared to more deprived patients (quintile 5 vs. quintile 1: OR 0.822, 95% CI 0.76–0.888, p < 0.0001). There was no correlation between marginalization and subsequent revision ORIF, ankle fusion, or ankle arthroplasty. Marginalized patients are at a significantly increased risk of infection and amputation following operatively treated ankle fractures. However, these complications are still extremely rare among this group. Thus, socioeconomic deprivation should not prohibit marginalized patients from receiving operative management for unstable ankle fractures

Even in patients with pronounced osteoporosis, fragility is rarely a sufficient or necessary cause of fracture. Almost always a trauma involved. Exposure to injuries varies with eg sociologic and climatologic. Since 1993 all injuries admitted to Ume̊ University hospital, Sweden, up to 58 parameters have been registered, eg mechanism, environment, involved products and diagnoses. The 12-year population-based injury register now comprises113,668 injuries (29,190 fractures). The absolute number of fractures is important from a practical clinical point of view. Most fractures occur in the extremities of life, perhaps due to both a weaker skeleton in growth and senescence and to exposure to injury. The earlier fracture peak in girls is caused by their earlier growth spurt. The higher and broader fracture peak in boys also reflects behavioural factors. Men continue to have more fractures until around 50, showing the effect of menopause. Radius fracture incidence in Ume̊ was about 15% higher than in Malmö, Sweden. But surprisingly hip fracture incidences were in the same order of magnitude in Malmö and Ume̊, which is remarkable considering the 8o latitude difference. But this may be explained by the different injury mechanisms in the two fractures. Low energy-trauma (fall in the same level) was most common in the extremities of life. However, most of the other mechanisms also involved low-moderate trauma, and high-energy trauma was rare. In this sub arctic register, outdoor slips was a common cause of fracture in middle age but as in other materials such injuries became less common with age. A further detailed analysis of the mechanisms causing fractures and soft tissue injuries could be a useful tool in prevention of fall injuries. Is it possible to identify frequent fallers or other accident prone people, before an incapacitating injury? This would indeed be a major public health challenge

Purpose: The purpose was to investigate the relationship between distal radius fracture malunion and arm-related disability. Methods: This prospective population-based cohort study included 143 patients above 18 years with acute distal radius fracture treated at one emergency hospital with either closed reduction and cast (55 patients) or with closed reduction and external and/or percutaneous pin fixation (88 patients). The patients were evaluated with the disabilities of the arm, shoulder and hand (DASH) questionnaire at baseline (inquiring about disabilities before fracture) and at 6, 12 and 24 months after the fracture. The 12-month follow-up also included the SF-12 health status questionnaire as well as clinical and radiographic examination. The patients were classified according to the degree of malunion (defined as dorsal tilt > 10 degrees or ulnar variance > 0 mm) into three groups; no malunion, malunion involving either dorsal tilt or ulnar variance, and malunion involving both dorsal tilt and ulnar variance. A Cox regression analysis was performed to determine the relationship between the 1-year DASH score (≥ 15 or < 15) and malunion adjusting for age, sex, fracture AO type, and treatment method and the relative risk (RR) of obtaining the higher DASH score was calculated. The number needed to harm (NNH) associated with malunion was calculated. Results: The mean DASH score at 1 year after fracture was about 10 points worse with each degree of increased malunion. The degree of malunion also correlated with SF-12 score, grip strength and supination. The regression analysis showed significantly higher disability with each degree of malunion compared to no malunion; for malunion involving either dorsal tilt or ulnar variance the RR was 2.4 (95% CI 1.0–5.7; p=0.038), and for malunion involving both dorsal tilt and ulnar variance the RR was 3.2 (95% CI 1.4–7.5; p=0.007). The NNH was 2.5 (95% CI 1.8–5.4). Conclusion: Malunion after distal radius fracture was associated with higher arm-related disability

There is widespread appreciation amongst orthopaedic surgeons of the importance of thromboprophylaxis. However much of the evidence is based on surrogate outcomes of clinical end-points. This population-based study aims to identify the incidence and trends in venous thromboembolic disease (VTE) following total hip (THR) and knee arthroplasty (TKR) with death or readmission for VTE up to two years following surgery for all patients in Scotland as the primary outcome. We used the Scottish Morbidity Record (SMR01) system to identify all patients undergoing hip or knee arthroplasty over the ten-year period from 1992 to 2001. Patients undergoing cataract surgery over the same period were identified as a control group. Record linkage for all patients to subsequent SMR01 and Registrar General records provided details of further admissions due to DVT or non-fatal PE and deaths within Scotland up to two years after the operation. The cause of death was determined from the Registrar General Records. The incidence of VTE (including fatal pulmonary embolism (PE)) three months following primary THR was 2.27% and primary TKR was 1.79%. The incidence of fatal PE within three months of THR was 0.22% and TKR was 0.15%. The majority of events occurred in the interval from hospital discharge to six weeks after surgery. There was no apparent trend over the period. An apparent reduction in the overall mortality within 365 days of surgery appears to be due to a reduction in the incidence of acute myocardial infarct. The data support the current advice that prophylaxis should be continued for at least six weeks following surgery. Despite increased uptake of prophylaxis regimens and earlier mobilisation, there has been no apparent change in the incidence of symptomatic VTE over the ten-years from 1992 to 2001

Aims

To provide normative data that can assess spinal-related disability and the prevalence of back or leg pain among adults with no spinal conditions in the UK using validated questionnaires.

Objective: Hospital volume is a known indicator for orthopaedic adverse events in patients undergoing total hip replacement. The aim of the current study was to evaluate the effect of hospital volume on the length of stay, re-admissions and complications of THR on a population-based level in Finland. Methods: Using the information from the Hospital Discharge Registry and that of four other National databases, 28,218 THRs performed for primary osteoarthritis were identified for the period covering 1998 to 2005. Hospitals were classified into four groups according to the number of primary and revision hip and knee replacements performed on an annual basis over the whole study period: 1–100 (Group 1), 101–300 (Group 2), 301–600 (Group 3) and 601 or over (Group 4). Logistic regression analysis and generalized linear models were used to study the effect of hospital volume on the length of stay, unscheduled re-admissions, re-operations, dislocations and infections. Results: The lengths of both the surgical treatment period and the uninterrupted institutional care were shorter for the very high volume hospitals (Group 4) than for the low volume hospitals (Group 1) (p< 0.0001). The odds ratio for dislocations (0.71, 95% CI 0.56–0.91) was significantly lower in the high volume hospitals (Group 3), than in the low volume hospitals (Group 1, the reference group). Conclusion: Specialization of hip replacements by high volume hospitals should reduce costs by significantly shortening length of stay, and may reduce the dislocation rate

A prior fragility fracture is one of the strongest predictors for a subsequent one, and this should be a target for secondary fracture prevention. All injured patients admitted to the emergency floor, Ume̊ University Hospital, Sweden, were registered. Between 1993–2004, there were 113,668 injury events, including 29,190 fracture events (one or more fractures at the same time), of whom 12,635 patients were _ 50 years. 1,994 of them had at least two fracture events; 500 had 3; 131 had 4; 35 had 5; and 11 had _ 6 fracture events. Mean age at the baseline fracture was 72.2 years and 75.5 at the second one. Thus, over 50 years of age, not less than 37% of all fractures were serial fractures, and 20% of the patients are serial fracturers. Hip and radius fracture were the most common ones, but 20% were fractures not traditionally labelled as fragility fractures. However, since more than 78% were caused by falls in the same level, most presumably have a fragility component. The interval between the two first fractures was longer than reported in several previous studies, mostly on patients participating in clinical trials. However, our material is population-based and unselected, since there is just one trauma facility in the area, and the general population is healthier than in-hospital or trial patients. On the other hand, there is a cut-off bias, so the interval is likely to be even longer. Interestingly, the difficult-to-treat hip fracture was the second common baseline fracture, the most common subsequent one, and hip-hip fractures were the most common combination, not less than 8.5% of the serial fractures. It is therefore clinically important to use the information provided by the fracture event, a fragility fracture may actually be regarded as a biomechanical test or a natural experiment. Trauma units, therefore, have an onus to screen for risk factors and inform patients about the treatment options, and to organize fracture liaison services. This seems to be especially cost-efficient for our oldest and frailest patients, but alas this is rarely done. A similar neglect of secondary prophylaxis and treatment after cardiovascular disorders would be an outrage! Secondary prevention is especially important since serial fractures are so common, often preventable, having a high impact on health-related quality of life

National guidelines encourage the use of total hip arthroplasty (THA) to treat intracapsular neck of femur fractures. There have been no population based studies appraising the surgical outcomes for this indication across an entire population. This study aims to calculate the complication rates for THA when performed for a fractured neck of femur and compare them to THA performed for primary osteoarthritis in the same population.

The Scottish Arthroplasty Project identified all THAs performed in Scotland for neck of femur fracture and osteoarthritis between 1st of January 2009 and 31st December 2014. Dislocation, periprosthetic infection and revision rates at 1 year were calculated.

The rate of dislocation, periprosthetic infection and revision at 1 year were all significantly increased among the fracture neck of femur cohort. In total 44046 THAs were performed, 38316 for OA and 2715 for a neck of femur fracture. 2.1% of patients (n=57) who underwent a THA for a neck of femur fracture suffered a dislocation in the 1st year postoperatively, compared to 0.9% (n=337) when the THA was performed for osteoarthritis. Relative Risk of dislocation: 2.4 (95% C.I. 1.8077–3.1252, p value <0.0001). Relative Risk of infection: 1.5 (95% C.I. 1.0496–2.0200, p value 0.0245) Relative Risk of revision: 1.5 (95% C.I. 1.0308–2.1268, p value 0.0336).

This is the first time a dislocation rate for THA performed for a neck of femur fracture has been calculated for an entire population. As the number of THAs for neck of femur fracture increases this dislocation rate will have clinical implications.

Introduction

Smoking, a modifiable factor, may adversely affect post-operative outcomes. Healthcare providers are increasingly denying smokers access to total hip arthroplasty (THA) until they stop smoking. Evidence supporting this is unclear. We assessed the effect of smoking on outcomes following THA.

There is a large variability associated with hip stem designs, patient anatomy, bone mechanical property, surgical procedure, loading, etc. Designers and orthopaedists aim at improving the performance of hip stems and reducing their sensitivity to this variability. This study focuses on the primary stability of a cementless short stem across the spectrum of patient morphology using a total of 109 femoral reconstructions, based on segmentation of patient CT scan data. A statistical approach is proposed for assessing the variability in bone shape and density [Blanc, 2012]. For each gender, a thousand new femur geometries were generated using a subset of principal components required to capture 95% of the variance in both female and male training datasets [Bah, 2013]. A computational tool (Figure 1) is then developed that automatically selects and positions the most suitable implant (distal diameter 6–17 mm, low and high offset, 126° and 133° CCD angle) to best match each CT-based 3D femur model (75 males and 34 females), following detailed measurements of key anatomical parameters. Finite Element contact models of reconstructed hips, subjected to physiologically-based boundary constraints and peak loads of walking mode [Speirs, 2007] were simulated using a coefficient of fricition of 0.4 and an interference-fit of 50μm [Abdul-Kadir, 2008]. Results showed that the maximum and average implant micromotions across the subpopulation were 100±7μm and 7±5μm with ranges [15μm, 350μm] and [1μm, 25μm], respectively. The computed percentage of implant area with micromotions greater than reported critical values of 50μm, 100μm and 150μm never exceeded 14%, 8% and 7%, respectively. To explore the possible correlations between anatomy and implant performance, response surface models for micromotion metrics were constructed using the so-called Kriging regression methodology, based on Gaussian processes. A clear nonlinear decreasing trend was revealed between implant average micromotion and the metaphyseal canal flare indexes (MCFI) measured in the medial-lateral (ML), anterio-posterior (AP) and femoral neck-oriented directions but also the average bone density in each Gruen zone. In contrast, no clear influence of the remaining clinically important parameters (neck length and offsets, femoral anteversion and CCD angle, standard canal flares, patient BMI and weight or stem size) to implant average micromotion was found. In conclusion, the present study demonstrates that the primary stability and tolerance of the short stem to variability in patient anatomy were high, suggesting no need for patient stratification. The developed methodology, based on detailed morphological analysis, accurate implant selection and positioning, prediction of implant micromotion and primary stability, is a novel and valuable tool to support implant design and planning of femoral reconstructive surgery.