Introduction. To introduce a new classification method and analyze related risk factor about lateral wall perforation associated with lower cervical pedicle screw and free-hand insertion technique. Methods. A Retrospective study was made to analyze 214 patients (1024 screws) with various cervical spine disorders, involved in pedicle screw instrumentation at C3-7 from July 2004 to July 2009. Researchers assessed the position of the screws in the pedicle by carefully probing intraoperatively and studying postoperative thin-slice computed tomography scan. Perforation of lateral wall was classified into two phases. Phase I refers to the burst of the pedicle by screw, which means that the length of screw threads penetrating the external cortex of pedicles on CT scan is 2 mm, whereas in Phase, the length is >2 mm. The Penetrated screws and related factors were analyzed though Backward Stepwise (Wald) Logistic regression. Results. During the follow-up, 2 screws were reported to be broken and 1 screw loosened. Of the screws inserted, total of 129 screws 12.60% have shown violated of lateral pedicle walls, included 101 screws (9.86%) causative of Phase I and 28 screws (2.73%) of Phase II. Two variance were deduced in the regression analysis, which concerned to ratio variance between inner and lateral walls, PRC 0.695, OR value = 2.003and angle difference variance between screws implanted and measurements preoperativePRC −1.542, OR value = 0.214). Conclusions. Free-hand lower cervical pedicle screw insertion in this series was comparatively safety. Phase I Penetration was believed to be safe of vertebral artery and Phase II faced to higher risk of artery damage. The main risk factor of lateral wall perforation was the ratio variance between inner and lateral wall, while the main protection factor was the angle difference variance between screws implanted and CT measurements

Aim. Debridement, antibiotics and implant retention (DAIR) is recommended for acute postoperative and late acute prosthetic joint infection (PJI). There are two recommend scores to predict its outcome, KLIC and CRIME 80 scores respectively. They have not been widely adopted for decision making. We aim to evaluate them in predicting DAIR failure in our cohort. Method. All patients submitted to DAIR after total hip or knee PJI, between 2010 and 2021, with a minimum one-year follow-up, were retrospectively evaluated. We excluded tumoral total joint replacements. KLIC score was applied to acute PJIs and CRIME 80 to late acute (LA) PJI. LA PJI was defined as the development of acute symptoms occurring ≥ 3 months after implantation. Repeat DAIR was performed as needed. Failure was defined as the need for implant removal, amputation, infection related death and suppressive antibiotic therapy. Results. We included 102 patients. The overall failure rate was 35.5% (36/102). There was no significant difference for the rate of failure in patients that had one DAIR and those who repeated DAIR - 32.5% (26/80) vs. 45.5% (10/22) (p=0.26). There were no significant correlations between KLIC or CRIME 80 scores and failure rates (p=0.54 and p=0.93 respectively, figure 1). Focusing specifically on the cohort who underwent repeat DAIR (n=22), KLIC and CRIME-80 score were also not associated with failure (p= 0.44 and p=0.50 respectively, figure 1). No host, pathogen or antibiotic treatment related factors were found to predict failure. Conclusions. In our cohort KLIC- and CRIME-80 scores failed to be predictive of DAIR failure, even in the cohort that needed repeat DAIR. We were unable to find any independent failure risk factors. For any tables or figures, please contact the authors directly

Aim. Musculoskeletal infection is a serious complication, however literature is lacking prospective data on its impact on mental health. The study aimed to assess mental health in patients with musculoskeletal infections and how they experience the possible mental and physical impairment. Method. All patients treated in our unit for musculoskeletal infections between July 2020 and March 2022 were prospectively included. To assess specific patient reported outcomes the following questionnaires were used: World-Health-Organization Quality-Of-Life (WHOQOL)-BREF and the Veterans-RAND-12Item Health Survey (VR-12) for mental & physical health; Patient-Health-Questionnaire (PHQ-8) for depression symptoms; Generalized-Anxiety-Disorder-Scale-7 (GAD-7) for anxiety symptoms and Somatic-Symptom-Disorder-B Criteria Scale (SSD-12) for experience of mental & physical impairment. The surveys were conducted at baseline, 6 and 12-weeks and 1-year. Results. In total 199 patients were included (31 fracture-related infections, 80 prosthetic joint infections, 40 diabetic foot syndromes and 48 other musculoskeletal infections). Physical health was significantly worse 6 weeks after treatment compared to baseline (WHOQOL p=.002; VR-12 p<.001), but significantly better at 3-months (p<.001; p=.006) and 12-months (p=.003; p<.001). Mental health was significantly worse at 3-months (WHOQOL p=.002), but at final follow-up significantly better (VR-12 p=.046). Social relationships (domain of WHOQOL) were perceived significantly worse 6 weeks and 12 months after treatment initiation (p=.003; p=.007), as were environmental factors. At baseline moderate to severe depression symptoms (PHQ-8≥10) and moderate to severe anxiety symptoms (GAD-7≥10) were observed in 14.6%, respectively 10.6% of all patients. At 12-months these were 7.4% and 3%. Over the course of treatment, only patients with DFS showed a significant change in experienced psychological or physical impairment, which was perceived significantly less compared 6 weeks to 12 months (p=.042). Conclusions. Patients with musculoskeletal infections suffer from a considerable impact on their mental health. The greatest impairment in physical health was seen 6 weeks after beginning of treatment. The psychological well-being was worse at 3-months. Environmental factors, such as mobility, activities of daily living and dependence on medication or medical treatment were worst at 3-months. Also increasingly worse social relationships over the course of treatment was observed. Further studies are needed to identify psychological impairment and related factors, as well as to determine how patients cope with their disease and treatment. This could serve as a foundation to implement treatment algorithms in order to improve patient related outcome and quality of life

Abstract. Objectives. Total hip replacement (THR) is one of the most successful and cost-effective interventions in orthopaedic surgery. Dislocation is a debilitating complication of THR and managing an unstable THR constitutes a significant clinical challenge. Stability in THR is multifactorial and is influenced by surgical, patient and implant related factors. It is established that larger diameter femoral heads have a wider impingement-free range of movement and an increase in jump distance, both of which are relevant in reducing the risk of dislocation. However, they can generate higher frictional torque which has led to concerns related to increased wear and loosening. Furthermore, the potential for taper corrosion or trunnionosis is also a potential concern with larger femoral heads, particularly those made from cobalt-chrome. These concerns have meant there is hesitancy among surgeons to use larger sized heads. This study presents the comparison of clinical outcomes for different head sizes (28mm, 32mm and 36mm) in primary THR for 10,104 hips in a single centre. Methods. A retrospective study of all consecutive patients who underwent primary THR at our institution between 1st April 2003 and 31st Dec 2019 was undertaken. Institutional approval for this study was obtained. Demographic and surgical data were collected. The primary outcome measures were all-cause revision, revision for dislocation, and all-cause revision excluding dislocation. Continuous descriptive statistics used means, median values, ranges, and 95% confidence intervals where appropriate. Kaplan-Meier survival curves were used to estimate time to revision. Cox proportional hazard regression analysis was used to compare revision rates between the femoral head size groups. Adjustments were made for age at surgery, gender, primary diagnosis, ASA score, articulation type, and fixation method. Results. 10,104 primary THRs were included; median age 68.6 years with 61.5% females. A posterior approach was performed in 71.6%. There were 3,295 hips with 28 mm heads (32.6%), 4,858 (48.1%) with 32 mm heads and 1,951 (19.3%) with 36 mm heads. Overall rate of revision was 1.7% with the lowest rate recorded for the 36mm group (2.7% vs. 1.3% vs. 1.1%). Cox regression analysis showed a decreased risk of all-cause revision for 32mm & 36mm head sizes as compared to 28mm; this was statistically significant for the 32mm group (p = 0.01). Risk of revision for dislocation was significantly reduced in both 32mm (p = 0.03) and 36mm (p = 0.03) head sizes. Analysis of all cause revision excluding dislocation showed no significant differences between head sizes. Conclusion. There was a significantly reduced risk of revision for all causes, but particularly revision for dislocation with larger head sizes (36mm & 32mm vs. 28mm). Concerns regarding increased risk of early revision for aseptic loosening, polyethylene wear or taper corrosion with larger heads appear to be unfounded in this cohort of 10,104 patients with a mean of 6.0-year follow-up. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Periprosthetic fractures around the femur during and after total hip arthroplasty (THA) remain a common mode of failure. It is important therefore to recognise those factors that place patients at increased risk for development of this complication. Prevention of this complication, always trumps treatment. Risk factors can be stratified into: 1. Patient related factors; 2. Host bone and anatomical considerations; 3. Procedural related factors; and 4. Implant related factors. Patient Factors. There are several patient related factors that place patients at risk for development of a periprosthetic fracture during and after total hip arthroplasty. Metabolic bone disease, particularly osteoporosis increases the risk of periprosthetic fracture. In addition, patients that smoke, have long term steroid use or disuse, osteopenia due to inactivity should be identified. A metabolic bone work up and evaluation of bone mineralization with a bone densitometry test can be helpful in identifying and implementing treatment prior to THA. Pre-operative Host Bone and Anatomic Considerations. In addition to metabolic bone disease the “shape of the bone” should be taken into consideration as well. Dorr has described three different types of bone morphology (Dorr A, B, C), each with unique characteristics of size and shape. It is important to recognise that not one single cementless implant may fit all bone types. The importance of templating a THA prior to surgery cannot be overstated. Stem morphology must be appropriately matched to patient anatomy. Today, several types of cementless stem designs exist with differing shape and areas of fixation. It is important to understand via pre-operative templating which stem works best in what situation. Procedural Related Factors. There has been a resurgence in interest in the varying surgical approaches to THA. While the validity and benefits of each surgical approach remains a point of debate, each approach carries with it its own set of risks. Several studies have demonstrated increased risk of periprosthetic fractures during THA with the use of the direct anterior approach. Risk factors for increased risk of periprosthetic fracture may include obesity, bone quality and stem design. Implant Related Factors. As mentioned there are several varying cementless implant shapes and sizes that can be utilised. There is no question that cementless fixation remains the most common mode of fixation in THA. However, one must not forget the role of cemented fixation in THA. Published results on long term fixation with cemented stems are comparable if not exceeding those of press fit fixation. In addition, the literature is clear that cemented fixation in the elderly hip fracture patient population is associated with a lower risk of periprosthetic fracture and lower risk of revision. The indication and principles of cemented stem fixation in THA should not be forgotten

Extended patient waiting lists for assessment and treatment are widely reported for planned elective joint replacement surgery. The development of regionally based Elective Orthopaedic Centres, separate from units that provide acute, urgent or trauma care has been suggested as one solution to provide protected capacity and patient pathways. These centres will adopt protocolised care to allow high volume activity and increased day-case care. We report the plan to establish a new elective orthopaedic centre serving a population of 2.4 million people. A census conducted in 2022 identified that 15000 patients were awaiting joint replacement surgery with predictions for further increases in waiting times. The principle of care will be to offer routine primary arthroplasty surgery for low risk (ASA 1 and 2) patients at a new regional centre. Pre-operative assessment and preparation will be undertaken digitally, virtually and/or in person at local centres close to the where patients live. This requires new and integrated pathways and ways of working. Predicting which patients will require perioperative transfusion of blood products is an important safety and quality consideration for new pathways. We reviewed all cases of hip and knee arthroplasty surgery conducted at our centre over a 12-month period and identified pre-operative patient related predictive factors to allow us to predict the need for the perioperative transfusion of blood products. We examined patient sex, age, pre-operative haemaglobin and platelet count, use of anti-coagulants, weight and body mass index to allow us to construct the Imperial blood transfusion tool. We have used the results of our study and the transfusion tool to propose the patient pathway for the new regional elective orthopaedic centre which we present

Aim. To describe the risk factors, microbiology and treatment outcome polymicrobial prosthetic joint infections (PJI) compared to monomicrobial PJI. Methods. Between January 2011 and December 2021, a total of 536 patients were diagnosed with PJI at our institution. Clinical records were revised, and 91(16.9%) had an isolation of two or more pathogens. Age, sex, previous conditions, Charlson comorbidity score, previous surgery, PJI diagnosis and surgical and antibiotic treatment, from the index surgery onwards were reviewed and compared between groups. Results. Polymicrobial PJI success rate was 57.1%, compared to 85.3% of the monomicrobial PJI(p=0.0036). There were no statistically significative differences between acute and chronic infections. In terms of related risk factors, revision surgery(p=0.0002), fracture(p=0.002), tobacco(p=0.0031) and Body Mass Index (BMI) between 20–25(p=0.0021) were associated to monomicrobial PJI, whereas overweight(p=0.005) and obesity(p=0.02) were linked to polymicrobial PJI. Regarding pathogens, the most common microorganism isolated in monomicrobial was S.aureus (33.5%), followed by S. epidermidis(20%) and gram negative bacilli (12.2%); while S. epidermidis(56%), gram negative bacilli (41.8%) and E.colli (30.8%) were the most frequent in the polymicrobial PJI. Enterococci(p=0.0008), S. epidermidis(p=0.007), E.colli (p=0.0008), gram negative bacilli (p=0.00003) and atypical bacteria (p=0.00001) statistically significative linked to polymicrobial PJI; while S.aureus (p=0.018) was related to monomicrobial PJI. Conclusion. Polymicrobial PJI showed worse outcome compared to monomicrobial PJI in our cohort. In terms of risk factors, overweight, obesity and some pathogens like gram negative bacilli, atypical bacteria, enterococci, S. epidermidis and E.colli were associated with Polymicrobial PJI

Aim. Chronic osteomyelitis reflects a progressive inflammatory process of destruction and necrosis affecting bone architecture. It presents a challenge to manage, requiring multi-stage multidisciplinary interventions, and the literature reports a wide variety of treatment strategies. This systematic scoping review aims to map and summarise existing literature on treatment of chronic osteomyelitis of the femur and tibia and investigates the full range of treatments reported in order to enhance the reader's understanding of how to manage this complex condition. Method. A comprehensive computer-based search was conducted in PubMed, EMBASE, MEDLINE, Emcare and CINAHL for articles reporting treatment of chronic tibial/femoral osteomyelitis. Two reviewers independently performed a two-stage title/abstract and full-text screening, followed by data collection. Studies were included if they described any treatment strategy including at least one surgical intervention. Key information extracted included causative pathogens, treatment protocol and outcome i.e. both success rate, defined as remission achieved following initial treatment with no recurrence during followup, and recurrence rate. Results. A total of 1230 articles were identified, and 40 articles (2529 patients) ultimately included. Although a wide variety of treatment protocols are reported, all revolve around three key principles: removal of infected tissue, dead space management and antibiotic therapy. Variations are evident when considering use of extensive versus more conservative debridement techniques, and delivery and regime of antibiotic therapy, e.g. whether to use one of, or both systemic and local delivery. The majority (84.5%) of patients presented with stage III or IV disease according to the Cierny-Mader classification and staphylococcus aureus was the most commonly isolated organism. Although there is heterogeneity across studies in reporting outcomes, with only 29 studies reporting success rate as defined in this review, 25 (86.2%) of these reported a success rate of at least 80%. Conclusions. It is difficult to identify the optimal treatment strategy when reporting of outcomes is not standardised across studies, even in the context of similar techniques being used. Success rates across studies may also vary depending on patient demographics, comorbidities, severity, type and number of causative pathogens and follow-up length. It is now essential to identify specific patient and treatment related factors that may affect clinical outcomes. Given the current dominance of case series in the literature, there is a need for randomised controlled trials to yield further information that could aid future efficient management

Ankle arthrodesis is the gold standard for treatment of end stage ankle arthritis. We analysed the data of 124 Ankle Arthrodesis (Open Ankle Arthrodesis (OAA) −27; Arthroscopic Ankle Arthrodesis (AAA)- 97) performed between January 2005 and December 2015 by fellowship trained foot and ankle surgeons in a single institution. Based on preoperative deformity (AAA- 28 degree valgus to 26 degrees varus; OAA- 41 degree valgus to 28 degree varus), they were subdivided into 2 groups based upon deformity more than 15 degrees. Union rates, time to union, length of hospital stay and patient related factors like smoking, alcoholism, diabetes, BMI were assessed. Mean age of patients was 60 years (Range 20 to 82 years)(Male:Female-87:32). Overall fusion rate was 93% in AAA and 89% in OAA (p=0.4). On sub group analysis of influence of preoperative deformity, there was no difference in union rates of AAA versus OAA. 7 patients in AAA and 3 in OAA required further procedures. Average time to union was 13.7 in AAA and 12.5 weeks in OAA (p=0.3). Average hospital stay was 2.6 days in AAA and 3.8 days in OAA (p=0.003). Smoking, alcoholism, Diabetes, BMI did not have any correlation with union rates. Although both AAA and OAA showed good union rates, hospital stay was significantly shorter in AAA. A larger deformity did not adversely affect union rates in AAA. Time to union was higher in AAA though it was statistically insignificant. Lifestyle risk factors did not have cumulative effect on union. We conclude that AAA is a reproducible method of treating end stage tibiotalar arthritis irrespective of preoperative deformity and patient related factors

Acute post-operative urinary retention (POUR) is a recognized complication following lower limb arthroplasty. Its occurrence may have patient and ultimately medico-legal implications. Identifying high-risk patients and the associated risk factors pre-operatively, is vital to tackle this issue and reduce its occurrence, which ultimately, may enhance the overall success of our operations. Our aim was to assess the incidence of POUR following elective lower limb arthroplasty and analyze the related factors that could potentially predict the likelihood of developing POUR in our patient cohort. A prospective audit of 158 patients was conducted in our department. POUR was defined as inability to pass urine voluntarily within the first 24 hours following elective lower limb arthroplasty leading to the insertion of a urinary catheter. Surgical-related factors including intra-operative fluid use, type of spinal anesthetic, duration of surgery, time from surgery till insertion of a urinary catheter as well as patient-related factors including medication, urological history and Body Mass index (BMI) was collected and analyzed. 21 (13.3%) patients developed post-operative urinary retention, 11 (52%) and 10 (48%) following knee and hip replacements respectively. Of which, 19 (90.5%) were male and 2 (9.5%) were female with an average age of 66 yrs. 13 (62%) had a previous urological history and 10 (48%) were on retention associated medication. Bupivacaine as a spinal anesthetic was associated with an increased risk of developing post-operative urinary retention. The average time till catheter insertion was 14 hrs. Only 2 (10%) had an unsuccessful TWOC on discharge. Bupivacaine as a spinal anesthetic and a previous urological history can be considered as risk factors for the development of POUR. Pre-operative urinary catheterization should be considered in this high-risk group of patients

Introduction. The purpose of this study was to evaluate the long term changes in bone mineral density (BMD) following implantation of a low-modulus composite femoral component designed to closely match the stiffness of the proximal femur and minimize stress shielding. Specifically, we asked: 1) How does BMD in the proximal femur change with time and with Gruen zone location; 2) Does BMD in the proximal femur stabilize after two years of implantation?. Methods. We retrospectively reviewed a subgroup of sixteen patients who had preoperative and postoperative DEXA scans in an FDA multi-center prospective trial of this composite stem. Five of these sixteen patients returned for long-term DEXA scans at a mean 22.0 years post-op (range 21.2–22.6 years). BMD in the 7 Gruen zones at final follow-up was compared to immediate post-operative and 2-year follow-up values. Percentage change was calculated and change in BMD was plotted against time from immediate post-operative measurements to each subsequent follow-up. Results. At the time of last follow-up, all stems were well fixed with signs of extensive osteointegration. There were no mechanical implant failures. In Gruen zone 1, patients underwent an overall decrease or little change in BMD, though one patient experienced a notable increase from initial post-op to the latest follow-up. The overall mean (+ SD) annual percent change in BMD in Gruen zone 1 was −0.31% ± 1.09%. When considering the change from the two-year DEXA scan to latest follow-up, two patients demonstrated a decrease in BMD and three patients demonstrated an increase in BMD in Gruen zone 1. All patients demonstrated progressive increase in BMD in Gruen zones 2, 3, 4, 5, and 6 from the initial post-op scan until last follow-up with mean annual percent changes ranging from 0.59% ± 0.50% in Gruen zone 6 to 2.78% ± 2.49% in Gruen zone 3. In our cohort, BMD progressively decreased with time in Gruen zone 7 for all patients with a mean decrease of 1.78% + 0.38% annually from the time of the initial post-op DEXA scan until last follow-up. This was consistent with prior reports with shorter term follow-up. Conclusions. Despite the extensively porous coated design of this stem and concerns about distal fixation and related stress shielding, we observed consistent DEXA scan evidence of increases in BMD in Gruen zones 2–6 and limitation of decreases in BMD exclusively to zone 7 and to a lesser extent zone 1. This is unlike reported results with several other extensively porous coated and proximally porous coated implants designed to obtain proximal fixation. These increases in BMD occurred despite the potential age-related decreases in BMD in the proximal femur that one would anticipate over the mean 22-year follow-up in this study. Clearly, “normal” physiologic loading of bone after THA is determined by a complex interaction between location of ingrowth, location and extent of endosteal contact of the implant in the proximal femur, stiffness of the stem and other implant design and patient related factors. The long-term observations of this study suggest that effective loading of the proximal femur occurs with this low-modulus stem and that this concept may have a role in the future of THA

Introduction: We examined the risk of blood transfusion in patients undergoing THA at 21 different orthopaedic departments in Denmark. Material and Methods: Patients with primary THA (n=21,773) registered in the Danish Hip Arthroplasty Registry between 1999 and 2006 were identified. Data on use of blood transfusion was collected from the Danish Transfusion Data Base (DTDB). The outcome was defined as red blood cell transfusion (yes/no) within 7 days after surgery. Modified Poisson regression analyses were used to estimate the risk of red blood cells transfusion (RR) and a 95% confidence interval (CI) adjusting for possible confounding factors including patient related factors (age, gender, comorbidity and diagnosis for primary THA) and surgery related factors (type of anestesia, type of osiffication prophylaxis type of operation, duration of surgery, and duration of admission. The risk of blood transfusion for each department was compared with the general risk of blood transfusion for all departments. Results: Overall, red blood cells transfusion was given to 8,162 of 21,773 patients (37%) (range between 16% and 64%, depending on department). After adjusting for different patient–and surgery-related factors, the adjusted RRs differed from 1.24 (95% CI, 2.07–3.43) to 0.52 (95% CI, 0.4–0.69) using all departments as reference. Coefficient of variation was 23%. Conclusions: Substantial differences in the risk of red blood cells transfusion among THA patients were found when comparing a sample of Danish orthopaedic departments. The differences in use of transfusions appeared not to be explained by a range of patient – and surgery – related factors and may thus reflect true differences in transfusion practice

Introduction. Total knee arthroplasty (TKA) is a proven treatment method for advanced knee arthritis in terms of pain relief, function restoration, and quality-of-life improvement. The TKA use has increased significantly over the past decade and the growing rate is more prominent in Asian countries. Thus, the revision TKA may also increase in recent days, which represents a burden to the national health care system. To the best of our knowledge, little information is currently available regarding the incidence and related factors of revision TKA in Asian countries on the basis of nationwide database. This study sought to find the incidence of revision TKA and related factors in South Korea using national database from 2007 to 2012. Material and Method. Data collected by the Health Insurance Review Agency of Korea, from 260,068 TKA patients between 2007 and 2012, were used to estimate the incidence of revision TKA according to age group, gender and hospital TKA and manufacturer prosthesis volume (i.e., the number of TKA procedures carried out at a given hospital, and the number of procedures performed using a given manufacturer's prosthesis, respectively). Age group and hospital and manufacturer volumes were categorized into three groups and TKA incidence rates were computed for groups stratified according to age, gender and hospital and manufacturer volumes. Result. Incidence rates per 100,000 person-years were as follows: 1) by age: < 65 years, 447.2; 65–74 years, 363.7; ≥ 75 years, 270.9, 2) by gender: male, 537.8; female, 346.1; 3) by hospital volume (procedures/year): < 20, 536.9; 20–199, 432.3; ≥ 200, 300.1; and 4) by manufacturer volume (prostheses/year): < 1500, 772.3; 1500–3999, 453.9; ≥ 4000, 345.6. TKA incidence rate in young males was significantly higher compared to that in elderly females. The difference in cumulative incidence, between hospitals with an annual volume of < 20 procedures and those with a volume of 20–199 procedures, was reduced for manufacturers with an annual volume of ≥ 4000. Similarly, the difference in cumulative incidence between manufacturers with an annual volume of < 1500 and those with a volume of 1500–3999 was reduced in hospitals with an annual volume of ≥ 200. Conclusions. Revision TKA incidence varied according to age, gender and hospital and manufacturer volumes. This data could inform clinical decisions and healthcare strategies

There is a growing requirement by governmental and other funders of research, that investigators pay attention to and integrate considerations of sex and gender in their health research studies. Doing so, the argument goes, will reduce data waste, lead to the generation of more complete and accurate evidence to apply to the delivery of health care, and hopefully improve outcomes for both male and female patients. Yet, it is not always clear what sex and gender mean and how best to apply these to the study of diverse health conditions and health service delivery. In this presentation sex, gender and other related factors will be considered in the context of fractures, fracture repair, and post-operative management. Examples of sex and gender bias, sex and gender differences, and the integration of sex and gender in research on fracture and fracture repair will be presented

Introduction. In total hip arthroplasty (THA), it is important to define the coordinate system of the pelvis and femur for standardization in measuring the implant alignment. A coronal plane of the pelvis (functional pelvic coordinates) in supine position has been recommended as the pelvic coordinates for cup orientation and an anatomical plane of the femur (posterior condylar plane: PCP) is widely used as the femoral coordinates to measure stem or femoral anteversion. It has been reported that the pelvic sagittal tilt in supine does not change a lot after THA. However, changes in the axial rotation of the posterior condylar plane after THA have not been well studied. If the horizontal tilt of PCP of the femur in a resting position changes a lot after THA, the combined anteversion theory cannot be functional. Therefore, we evaluated the angulation changes of the posterior condylar plane after THA and analyzed the related factors by using CT images. Methods. Forty patients (5 men and 35 women, mean age 58 years) with hip osteoarthritis who had undergone THA were the subjects of this study. CT images used for measurements were taken preoperatively (preop-CT) and 3 weeks after THA (postop-CT), and more than 2 years after THA (2nd postop-CT). Measurements were done on the reconstructed CT images using 3D viewer software. The axial rotation of the femur was measured as the angle between the posterior condylar line (PCL) and a line through the bilateral anterior superior iliac spines. To analyze the factors relating to the rotational change of the femur, change in femoral anteversion, leg length, and leg medialization after THA were also measured. Surgical approach (posterolateral: 32 cases, direct anterior: 8 cases) was also evaluated as a factor relating to the rotational change. Results. PCL was externally rotated at an average angle of 3.3° at preop-CT, −10.4° at postop-CT, and −7.2° at 2nd postop-CT. There was a significant difference between preop-CT and postop-CT, preop-CT and 2nd postop-CT (p<0.01, respectively). Femoral anteversion decreased 0.5°, the leg was lengthened 11.7mm, and was medialized 8.5mm after THA. In the analysis of the related factors, only the leg length change and the amount of leg medialization significantly correlated with the rotational change between preop-CT and postop-CT (β=−0.367, −0.316, respectively). On the other hand, no factors correlated with the rotational change between preop-CT and 2nd postop-CT. Discussion. PCL at a resting position internally rotated 13.7° after THA and remained 10.5° internally rotated from the preoperative position at more than 2 years after THA. This internal rotation after THA may have occurred by releasing the external contracture caused by osteoarthritis. Because the PCL at a resting position internally rotates approximately 10° after THA, we have to consider this change when we calculate the range of motion of the hip in the combined anteversion theory. Conclusion. PCL at a resting position internally rotates approximately 10°after THA and we may need to consider this change in the combined anteversion theory

Introduction: The acetabular component in primary THA is placed on pathologic bone stock. Little is known about histology and its impact on aseptic cup loosening. We therefore investigated undecalcified acetabular bone biopsies taken prior to primary THA and at the time of revision surgery. Study design: In a prospective study, starting 01/1993, a bone biopsy of the acetabulum out of zone 1 according to De Lee and Charnley is taken in each primary THA in a standardized manner. In case of revision surgery of the cup, another biopsy is taken again. Between 01/1993 and 08/1997 351 cementless titanium shells with screws cups have been implanted at our institution. The average age at operation was 68 years (range 29–90 years). In 88% osteoarthritis was the primary diagnosis. Biopsies were classified as normal bone (type I), increased sclerosis (type II), restless bone (type III) or dead bone (type IV) according to a classification developed in our institution. Biopsies with a special entity such as rheumatoid arthritis are grouped «others». The initial diagnosis on the pre-operative X-ray was correlated to the results of the biopsies. Signs for aseptic loosening of the cup were defined on the complete x-ray series. All explanted cups were analysed for signs of impingement or increased wear. Results: 8 cups (8 patients) had to be revised until August 2004 (average age at revision 63.6years, range 49.6–77.8 years). The initial diagnosis was osteoarthritis in 5 cases, twice avascular necrosis of the femoral head and 1 rheumatoid arthritis. 5 times we found metal-on-metal, 3 times PE-ceramic bearings. We found one of each biopsies in type I and type IV, 2 in type II and type III. 2 biopsies had to be grouped «others». At time of revision one biopsy initially grouped as type III had to be reclassified as «others». 2 cups were revised due to late haematogenous infection. 3 cases showed a direct relation between the result of the biopsy and failure of the cup. In 1 case we found surgical failure, though impingement and a type IV biopsy as combined reasons for failure. 2 cups (2 patients) revised after 1.2 years, immunhistological reaction due to metal-on-metal could have been the reason for failure (still under investigation). Discussion: Surgical failures and implant related factors are accused as major reasons for loosening of the cup in THA, patient related factors often neglected. The acetabular bone quality, as one patient related factor, showed in almost half of the cases analysed a correlation with later acetabular loosening. One should therefore be aware of acetabular bone quality as one factor for loosening of the cup when monitoring acetabular implants, especially when newly introduced

Aims

Mendelian randomization (MR) is considered to overcome the bias of observational studies, but there is no current meta-analysis of MR studies on rheumatoid arthritis (RA). The purpose of this study was to summarize the relationship between potential pathogenic factors and RA risk based on existing MR studies.

Introduction. Wear of polyethylene tibial inserts has been cited as being responsible for up to 25% of revision surgeries, imposing a very significant cost burden on the health care system and increasing patient risk. Accurate measurement of material loss from retrieved knee bearings presents difficult challenges because gravimetric methods are not useful with retrievals and unworn reference dimensions are often unavailable. Geometry and the local anatomy restrict in vivo radiographic wear analysis, and no large-scale analyses have illuminated long-term comparative wear rates and their dependence on design and patient factors. Our study of a large retrieval archive of knee inserts indicates that abrasive/adhesive wear of polyethylene inserts, both on the articular surface and on the backside of modular knees is an important contributor to wear, generation of debris and integrity of locking geometry. The objective of the current study is to quantify wear performance of tibial inserts in a large archive of retrieved knees of different designs. By assessing wear in a large and diverse series, the goal is to discern the effect on wear performance of a number of different factors: patient factors that might help guide treatment, knee design factors and bearing material factors that may inform a surgeon's choice from among the array of arthroplasty device options. Methods. An IRB approved retrieval database was queried for TKA designs implanted between 1997 and 2017. 1385 devices from 5 TKA designs were evaluated. Damage was ranked according to Hood's method, oxidation was determined through FTIR, and wear was determined through direct measurement of retrieved inserts using a previously established protocol. Design features (e.g. materials, conformity, locking mechanisms, stabilization, etc.) and patient demographics (e.g. age, weight, BMI, etc.) were cataloged. Multivariate analysis was performed to isolate factors contributing to wear, oxidation, and damage. Results. Wear and oxidation were both found to scale with time in vivo in conventional and crosslinked polyethylene. Wear rate was also found to scale with time in vivo, but was not found to be a function of oxidation. Regression shows patient age and female sex to correlate negatively with wear rate. Polished trays, crosslinked polyethylene, and constrained knee designs are all correlated with decreased wear rates. Discussion. While this study indicates that loosening and infection are predominant causes for TKA revision, wear related failure remains common. We believe this to be the largest existing comparative study of modern TKA wear rates. Insert wear is shown to correlate with several patient factors. Wear performance also varies significantly between knee designs, polyethylene material choice and tray surface finish. When compared to a historical standard for knee wear rates, all designs evaluated in the current study exhibited significant improvements in wear rates. Retrieval analysis can provide insight into implant and patient related factors that contribute to knee wear, with the goal of improving patient outcomes and best matching design decisions to patient populations

Aims

The mechanism by which synovial fluid (SF) kills bacteria has not yet been elucidated, and a better understanding is needed. We sought to analyze the antimicrobial properties of exogenous copper in human SF against Staphylococcus aureus.

Introduction. Implant-cement debonding at the knee has been reported previously [1]. The strength of the mechanical interlock of bone cement on to an implant surface can be associated with both bone cement and implant related factors. In addition to implant surface profile, sub-optimal mixing temperatures and waiting times prior to cement application may weaken the strength of the interlock. Aims. The study aimed to investigate the influence of bone cement related factors such as mixing temperature, viscosity, and the mixing and waiting times prior to application, in combination with implant surface roughness, on the tensile strength at the interface. Materials and Methods. Tensile tests were carried out on two types of hand-mixed cement, high (HV) and medium viscosity (MV), sandwiched between two cylindrical Cobalt-Chrome coupons with either smooth (60 grit) or rough (20 grit) surface finishes. 144 Specimens were prepared with a cement thickness layer of 2.5 mm in customised rigs (Figure 1). The samples were grouped and tested at two mixing temperatures (23 and 19 degrees), at different mixing times (HV-30s, MV-45s). Waiting times after mixing were varied between early (1.5 min), optimal (4.5 min) or late (8 min); for HV and 4 min, 7.5 min and 11 min for MV cements. All the samples were cured for 24 hours prior to testing. The peak force and stress was calculated for all specimens. Results and Conclusion. Surface Finish: Rough surfaced samples had significantly higher (p < 0.05) mean tensile forces and stress than smooth samples at both 19 and 23 degrees across HV and MV cement types. Cement Type: MV cements, when applied to rough samples with waiting times of 4 minutes at 23 degrees, and 11 minutes at 19 degrees, resulted in the highest peak tensile forces, followed by 7.5 minutes at 23 and 19 degrees respectively (Figure 2). Temperature at different application times for rough and smooth samples: for MV cement, rough samples prepared at 23 degrees, 4 minutes, and smooth samples at 19 degrees, 7.5 minutes were found to be significantly better (p < 0.05) than their counterparts. For HV cement, 23 degrees was found to be better (p < 0.05) for smooth samples at applications times of 4.5 and 8 minutes and 19 degrees for application times of 1.5 minutes. No significant difference was noted for rough samples for the same. Application times at different temperatures for rough and smooth samples: at both 19 and 23 degrees, there were no differences between application times within the rough sample groups for HV or MV. However, for smooth samples, HV cement, tensile forces were significantly higher (p < 0.05) at 23 degrees in the following order; 8 minutes > 4.5 minutes > 1.5. The results show that implant surface roughness and cement mixing time, temperature, viscosity and application times affect the strength of the interlock at the interface