Aims. The aim of this study was to observe the implications of withholding total joint arthroplasty (TJA) in morbidly obese patients. Patients and Methods. A total of 289 morbidly obese patients with end-stage osteoarthritis were prospectively followed. There were 218 women and 71 men, with a mean age of 56.3 years (26.7 to 79.1). At initial visit, patients were given information about the risks of TJA in the morbidly obese and were given referral information to a bariatric clinic. Patients were contacted at six, 12, 18, and 24 months from initial visit. Results. The median body mass index (BMI) at initial visit was 46.9 kg/m. 2. (interquartile range (IQR) 44.6 to 51.3). A total of 82 patients (28.4%) refused to follow-up or answer phone surveys, and 149 of the remaining 207 (72.0%) did not have surgery. Initial median BMI of those 149 was 47.5 kg/m. 2. (IQR 44.6 to 52.5) and at last follow-up was 46.7 kg/m. 2. (IQR 43.4 to 51.2). Only 67 patients (23.2%) went to the bariatric clinic, of whom 14 (20.9%) had bariatric surgery. A total of 58 patients (20.1%) underwent TJA. For those 58, BMI at initial visit was 45.3 kg/m. 2. (IQR 43.7 to 47.2), and at surgery was 42.3 kg/m. 2. (IQR 38.1 to 46.5). Only 23 patients (39.7%) of those who had TJA successfully achieved BMI < 40 kg/m. 2. at surgery. Conclusion. Restricting TJA for morbidly obese patients does not incentivize weight loss prior to arthroplasty. Only 20.1% of patients ultimately underwent TJA and the majority of those remained morbidly obese. Better resources and coordinated care are required to optimize patients prior to surgery. Cite this article: Bone Joint J 2019;101-B(7 Supple C):28–32

Aims. The purpose of this study was to assess total knee arthroplasty (TKA) volume and rates of early complications in morbidly obese patients over the last decade, where the introduction of quality models influencing perioperative care pathways occurred. Methods. Patients undergoing TKA between 2011 to 2018 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Patients were stratified by BMI < 40 kg/m. 2. and ≥ 40 kg/m. 2. and evaluated by the number of cases per year. The 30-day rates of any complication, wound complications, readmissions, and reoperation were assessed. Trends in these endpoints over the study period were compared between groups using odds ratios (ORs) and multivariate analyses. Results. In total, 314,695 patients underwent TKA and 46,362 (15%) had BMI ≥ 40 kg/m. 2. The prevalence of morbid obesity among TKA patients did not change greatly, ranging between 14% and 16%. Reoperation rate decreased from 1.16% to 0.96% (odds ratio (OR) 0.81 (95% confidence interval (CI) 0.66 to 0.99)) for patients with BMI < 40 kg/m. 2. , as did rates of readmission (4.46% to 2.87%; OR 0.61 (0.55 to 0.69)). Patients with BMI ≥ 40 kg/m. 2. also had fewer readmissions over the study period (4.87% to 3.34%; OR 0.64 (0.49 to 0.83)); however, the rate of reoperation did not change (1.37% to 1.41%; OR 0.99 (0.62 to 1.56)). Significant improvements were not observed for infective complications over time for either group; patients with BMI ≥ 40 kg/m. 2. had increased risk of both deep infection and wound complications compared to non-morbidly obese patients. Rate of any complication decreased for all patients. Conclusion. The proportion of TKAs in morbidly obese patients has not significantly changed over the past decade. Although readmission rates improved for all patients, reductions in reoperation in non-morbidly obese patients were not experienced by the morbidly obese, resulting in a widening of the complication gap between these cohorts. Care improvements have not lowered the differential risk of infective complications in the morbidly obese. Cite this article: Bone Joint J 2021;103-B(6 Supple A):38–44

Aims. It has been shown that the preoperative modification of risk factors associated with obesity may reduce complications after total knee arthroplasty (TKA). However, the optimal method of doing so remains unclear. The aim of this study was to investigate whether a preoperative Risk Stratification Tool (RST) devised in our institution could reduce unexpected intensive care unit (ICU) transfers and 90-day emergency department (ED) visits, readmissions, and reoperations after TKA in obese patients. Methods. We retrospectively reviewed 1,614 consecutive patients undergoing primary unilateral TKA. Their mean age was 65.1 years (17.9 to 87.7) and the mean BMI was 34.2 kg/m. 2. (SD 7.7). All patients underwent perioperative optimization and monitoring using the RST, which is a validated calculation tool that provides a recommendation for postoperative ICU care or increased nursing support. Patients were divided into three groups: non-obese (BMI < 30 kg/m. 2. , n = 512); obese (BMI 30 kg/m. 2. to 39.9 kg/m. 2. , n = 748); and morbidly obese (BMI > 40 kg/m. 2. , n = 354). Logistic regression analysis was used to evaluate the outcomes among the groups adjusted for age, sex, smoking, and diabetes. Results. Obese patients had a significantly increased rate of discharge to a rehabilitation facility compared with non-obese patients (38.7% (426/1,102) vs 26.0% (133/512), respectively; p < 0.001). When stratified by BMI, discharge to a rehabilitation facility remained significantly higher compared with non-obese (26.0% (133)) in both obese (34.2% (256), odds ratio (OR) 1.6) and morbidly obese (48.0% (170), OR 3.1) patients (p < 0.001). However, there was no significant difference in unexpected ICU transfer (0.4% (two) non-obese vs 0.9% (seven) obese (OR 2.5) vs 1.7% (six) morbidly obese (OR 5.4); p = 0.054), visits to the ED (8.6% (44) vs 10.3% (77) (OR 1.3) vs 10.5% (37) (OR 1.2); p = 0.379), readmissions (4.5% (23) vs 4.0% (30) (OR 1.0) vs 5.1% (18) (OR 1.4); p = 0.322), or reoperations (2.5% (13) vs 3.3% (25) (OR 1.2) vs 3.1% (11) (OR 0.9); p = 0.939). Conclusion. With the use of a preoperative RST, morbidly obese patients had similar rates of short-term postoperative adverse outcomes after primary TKA as non-obese patients. This supports the assertion that morbidly obese patients can safely undergo TKA with appropriate perioperative optimization and monitoring. Cite this article: Bone Joint J 2021;103-B(6 Supple A):45–50

The results of 41 consecutive total knee replacements performed on morbidly obese patients with a body mass index > 40 kg/m. 2. , were compared with a matched group of 41 similar procedures carried out in non-obese patients (body mass index < 30 kg/m. 2. ). The groups were matched for age, gender, diagnosis, type of prosthesis, laterality and pre-operative Knee Society Score. We prospectively followed up the patients for a mean of 38.5 months (6 to 66). No patients were lost to follow-up. At less than four years after operation, the results were worse in the morbidly obese group compared with the non-obese, as demonstrated by inferior Knee Society Scores (mean knee score 85.7 and 90.5 respectively, p = 0.08; mean function score 75.6 and 83.4, p = 0.01), a higher incidence of radiolucent lines on post-operative radiographs (29% and 7%, respectively, p = 0.02), a higher rate of complications (32% and 0%, respectively, p = 0.001) and inferior survivorship using revision and pain as end-points (72.3% and 97.6%, respectively, p = 0.02). Patients with a body mass index > 40 kg/m. 2. should be advised to lose weight prior to total knee replacement and to maintain weight reduction. They should also be counselled regarding the inferior results which may occur if they do not lose weight before surgery

Introduction. Morbid obesity (BMI>40) is a significant risk factor for complications following total joint arthroplasty (TJA). As such many have a restrictive practice of withholding elective primary TJA in the morbidly obese. The purpose of this study was to observe the implications of this practice. Methods. From 2012 to 2014, 289 patients with morbid obesity and end-stage OA of the hip or knee were prospectively followed. At initial visit, patients were given a packet on risks of TJA in the morbidly obese and referral information to a weight loss clinic. Patients were contacted at 6, 12, 18 and 24 months from initial visit for PROs, and BMI changes. The average age of patients was 56 (26.7–79.1) there were 218 females and 71 males. Results. The average BMI at initial visit was 46.9 (39.9–68.2). 85 patients (29%) refused additional follow up or to answer phone surveys regarding their status. 146 patients (50.5%) have not had surgery. Initial BMI in this cohort was 47.4 (39.9–68.6) and at last follow up was 46.8 (28.9–70.8). Of those, 11 (7.5%) had a last follow up BMI≤40. Only 23% of patients went to the bariatric clinic and 13% had bariatric surgery. Fifty-eight patients (20.1%) underwent TJA. BMI at initial visit was 45.3 (40.3–55.4), and at the time of surgery was 41.3 (27.5–69.5). Only 20 patients (6.9% of those followed) have successfully achieved BMI < 40 and had surgery. Of those, 14 (70%) had a last follow up BMI≤40, and 2 (10%) had a last follow up BMI≤30. Conclusions. The practice of restricting total joint replacement to morbidly obese patients does not serve as an incentive to lose weight prior to arthroplasty. Only 20% of patients ultimately underwent TJA and the majority of those remained morbidly obese. Better resources and collaborative care among specialties is required to optimize patients prior to surgery

Abstract. Aims. The association between body mass index (BMI) and venous thromboembolism (VTE) is well studied, but remains unclear in the literature. We aimed to determine whether morbid obesity (BMI≥40) was associated with increased risk of VTE following total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA), compared to those of BMI<40. Methods. Between January 2016 and December 2020, our institution performed 4506 TKAs and 449 UKAs. 450 (9.1%) patients had a BMI≥40. CT pulmonary angiography (CTPA) for suspected pulmonary embolism (PE) and ultrasound scan for suspected proximal deep vein thrombosis (DVT) were recorded up to 90 days post-operatively. Results. When comparing those of BMI<40 to those with BMI≥40, there was no difference in incidence of PE (1.0% vs 1.1%, p=0.803) or proximal DVT (0.4% vs 0.2%, p=0.645). There was no difference in number of ultrasound scans ordered (p=0.668), or number of CTPAs ordered for those with a BMI≥40 (p=0.176). The percentage of patients with a confirmed PE or proximal DVT were 24.2% and 3.9% respectively in the BMI<40 group, compared to 20.0% (p=0.804) and 2.3% (p=0.598) in the BMI≥40 group. Conclusion. Morbid obesity was not associated with increased risk of PE or proximal DVT within 90 days of TKA or UKA. Overall, 76.3% of CTPAs and 96.2% of ultrasound scans were negative. Increasing the threshold for VTE investigation would reduce the rate of negative investigations. Establishing more effective risk stratification protocols, to guide investigation, would likely reduce unnecessary imaging

Aims. This study investigated the influence of body mass index (BMI) on the post-operative fall in the level of haemoglobin (Hb), length of hospital stay (LOS), 30-day re-admission rate, functional outcome and quality of life, two years after total knee arthroplasty (TKA). Patients and Methods. A total of 7733 patients who underwent unilateral primary TKA between 2001 and 2010 were included. The mean age was 67 years (30 to 90). There were 1421 males and 6312 females. The patients were categorised into three groups: BMI < 25.0 kg/m. 2. (normal); BMI between 25.0 and 39.9 kg/m. 2. (obese); and BMI ≥ 40.0 kg/m. 2. (morbidly obese). Results. Compared with the normal and obese groups, the mean LOS was longer by one day (95% confidence interval (CI) 0 to 2) in the morbidly obese group (p = 0.003 and p = 0.001 respectively). The 30-day re-admisison rate was also higher in the morbidly obese group compared to the obese group (OR 2.323, 95% CI 1.101 to 4.900, p = 0.024); and showed a higher trend compared to the normal group (OR 1.850, 95% CI 0.893 to 3.831, p = 0.100). However, the morbidly obese group had a smaller drop in post-operative Hb level by a mean of 0.5 g/dl (0.3 to 0.6) and 0.3 g/dl (0.1 to 0.5), when compared with the normal and obese groups respectively (both p < 0.001). Furthermore, the mean improvement in Oxford Knee Score (OKS) and Knee Society Knee Score (KSKS) at two years follow-up was three points (two to four) and five points (two to seven) more in the morbidly obese group than in the normal group (both p < 0.001). The mean improvement in Knee Society Function Score, and Physical and Mental Component Scores of Short Form-36 were comparable between the three BMI groups (p = 0.736, p = 0.739 and p = 0.731 respectively). The ten-year rate of survival was 98.8% (98.0 to 99.3), 98.9% (98.5 to 99.2) and 98.0% (95.8 to 100), for the normal, obese and morbidly obese groups, respectively (p = 0.703). Conclusion. Although morbidly obese patients have a longer LOS and higher 30-day re-admission rate after TKA, they have a smaller drop in post-operative Hb level and larger improvement in OKS and KSKS at two years follow-up. The ten-year rate of survival of TKA was also comparable with those with a normal BMI. . Take home message: Morbidly obese patients should not be excluded from the benefits of TKA. Cite this article: Bone Joint J 2016;98-B:780–5

We carried out a prospective, continuous study on 529 patients who underwent primary total knee replacement between January 2006 and December 2007 at a major teaching hospital. The aim was to investigate weight change and the functional and clinical outcome in non-obese and obese groups at 12 months post-operatively. The patients were grouped according to their pre-operative body mass index (BMI) as follows: non-obese (BMI < 30 kg/m. 2. ), obese (BMI . 3. 30 to 39 kg/m. 2. ) and morbidly obese (BMI > 40 kg/m. 2. ). The clinical outcome data were available for all patients and functional outcome data for 521 (98.5%). Overall, 318 (60.1%) of the patients were obese or morbidly obese. At 12 months, a clinically significant weight loss of ≥ 5% had occurred in 40 (12.6%) of the obese patients, but 107 (21%) gained weight. The change in the International Knee Society score was less in obese and morbidly obese compared with non-obese patients (p = 0.016). Adverse events occurred in 30 (14.2%) of the non-obese, 59 (22.6%) of the obese and 20 (35.1%) of the morbidly obese patients (p = 0.001)

Introduction. Perioperative optimization efforts have improved outcomes following primary total knee arthroplasty (TKA). However, morbidly obese patients continue to have increased rates of complications. The purpose of this study was to assess if rates of early complications after TKA have similarly improved for both morbidly obese and non-morbidly obese patients. Methods. Elective, primary TKA patients from 2011–2018 were identified in the National Surgical Quality Improvement Program database. Patients were stratified by body mass index (BMI) <40 kg/m. 2. and ≥40 kg/m. 2. Thirty-day rates of infectious complications, readmissions, and reoperation were assessed. Trends in these endpoints over the study period were compared between BMI groups utilizing odds ratios (OR) and multivariate analyses. Results. In total, 314,719 patients underwent TKA and 46,386 (15%) had BMI ≥40 kg/m. 2. From 2011–2018, the reoperation rate significantly improved from 1.2% to 1.0% (OR: 0.6 [0.6–0.7]) for patients with BMI <40 kg/m. 2. , as did rates of readmission (4.5% to 2.9%, OR: 0.8 [0.7–0.99]). Patients with BMI ≥40 kg/m. 2. also had a significant decrease in the rate of readmission over the study period (4.9% to 3.3%, OR: 0.6 [0.5–0.8]); however, the rate of reoperation did not significantly change (1.4% to 1.4%, OR: 1.0 [0.6–1.6]). Significant improvements were not observed for infectious complications over time for either group. However, patients with BMI ≥40 kg/m. 2. consistently had increased risk of both deep infection from 2014–2018 (2014 OR: 2.2 [1.4–3.4], 2018: 2.2 [1.6–3.0]) and wound complications from 2011–2018 (2011 OR: 1.7 [1.2–2.6], 2018 OR: 2.0 [1.7–2.4]) compared to non-morbidly obese patients. Conclusion. Although readmission rates significantly decreased for all patients, improvements in reoperation rates observed in non-morbidly obese patients were not experienced by the morbidly obese – resulting in a widening of the complication gap between these cohorts. Care improvements have not lowered the differential risk of infectious complications compared to non-morbidly obese

Introduction. Previous research has indicated that preoperative modification of risk factors associated with obesity may reduce complications after TKA. However, the optimal method is still debated. This study aims to investigate whether a preoperative Risk Stratification Tool (RST) devised by our institution to optimize obese patients can reduce unexpected ICU transfers, and 90-day ED visits, readmissions, and reoperations. Methods. We retrospectively reviewed 1,724 consecutive risk stratified patients undergoing primary unilateral TKA. The mean age was 64.8 years and average body mass index (BMI) was 34.2 kg/m2. All patients underwent preoperative optimization using the RST. We first compared our primary variables of interest between obese (BMI>30, n=1,189) and non-obese patients (n=535). Patients were then divided into 3 groups (I-non-obese, II-obese (30–39.9 kg/m2) and III-morbidly obese ((>40 kg/m2)) and logistic regression was used to evaluate outcomes among the groups adjusted for age, sex, smoking history and diabetes. Results. Overall, obese patients had an increased rate of discharge to facility compared to non-obese patients (38.0% vs 25.9%, p<0.001). After stratifying by BMI (group I (n=535), II (n=793), III (n=396)), discharge to facility remained higher relative to non-obese (25.9%) in both obese (34.0%, OR 1.6, CI 1.3–2.1) and morbidly obese (45.8%, OR 3.0, CI 2.2–4.1) patients. However, there was no difference in unexpected ICU transfer (0.6% non-obese vs 1.0% obese [OR 1.9, CI 0.5–7.3] vs 1.8% morbidly obese [OR 4.1, CI 1.0–17.2]), ED visits (8.6% vs 10.5% [OR 1.3, CI 0.9–1.9] vs 10.3% [OR 1.2, CI 0.7–1.9]), readmissions (4.7% vs 4.3% [OR 1.0, CI 0.6–1.8] vs 4.8% [OR 1.3, CI 0.7–2.6]), or reoperations (2.4% vs 3.3% [OR 1.3, CI 0.6–2.5] vs 3.0% [OR 1.0, CI 0.7–2.2]). Conclusion. Use of a preoperative risk stratification tool is effective at lowering the risk of short-term complications after TKA in obese patients to similar levels as non-obese patients. For any figures or tables, please contact the authors directly

Introduction. In the lower extremity, lymphedema is characterized by fluid buildup and swelling which can lead to fibrosis of the skin and recurring soft-tissue infections. Risk factors include obesity, older age, lower extremity surgery, and radiotherapy. There is currently a paucity of data examining the impact of lymphedema in primary total knee arthroplasty (TKA). The purpose of this study was to review outcomes following primary TKA performed in patients with lymphedema compared to a matched cohort with primary osteoarthritis. Methods. Over a 19-year period (1998–2016), 144 patients underwent primary TKA with a preceding diagnosis of ipsilateral lymphedema (Table 1). There were 114 (79%) females, a mean age of 69 years, and mean BMI of 37.1 kg/m2. Mean follow-up was 7-years (range 2–17 years). A blinded analyst completed a 1:2 match of patients with lymphedema to a group of patients without lymphedema undergoing primary TKA for osteoarthritis during the same period. Matching criteria included sex, age, date of surgery, and BMI. Matched controls included 228 (79%) females along with a mean age and BMI of 69 and 36.4 kg/m2. The mean follow-up for the comparison cohort was 8 years (range 2–18 years). There were no significant differences between groups on the evaluated baseline parameters. Results: Patients with a history of lymphedema were at a significantly increased risk of revision TKA (HR 7.60, P<0.001), reoperation for any cause (HR 2.87, P<0.001), and postoperative infection (HR 6.19, P<0.001). Patients with lymphedema were also at increased risk for periprosthetic fracture (p=0.04) and tibial component loosening (p=0.01). Morbid obesity increased the risk of reoperation (HR 2.11, p=0.02) and trended toward increased risk of revision TKA (HR 2.29, p=0.059) and infection (HR 2.37, p=0.06). Discussion: Patients with lymphedema are at significantly increased risk of revision, reoperation, and infection following primary TKA. This data highlights the need for appropriate patient counseling in this population and optimization of lymphedema management before and after TKA. Results. Patients with a history of lymphedema were at a significantly increased risk of revision TKA (HR 7.60, P<0.001), reoperation for any cause (HR 2.87, P<0.001), and postoperative infection (HR 6.19, P<0.001). Patients with lymphedema were also at increased risk for periprosthetic fracture (p=0.04) and tibial component loosening (p=0.01). Morbid obesity increased the risk of reoperation (HR 2.11, p=0.02) and trended toward increased risk of revision TKA (HR 2.29, p=0.059) and infection (HR 2.37, p=0.06). Discussion. Patients with lymphedema are at significantly increased risk of revision, reoperation, and infection following primary TKA. This data highlights the need for appropriate patient counseling in this population and optimization of lymphedema management before and after TKA. For any figures or tables, please contact authors directly

Introduction. At a time when many surgeons are reluctant to perform a unilateral TKA in the obese patient, little is written on the safety and efficacy of bilateral simultaneous TKA in this same patient population. While these potential benefits are attractive to patients, surgeons may be hesitant to perform bilateral TKA due to the greater physical demand placed on the patient, and a potential increase in postoperative complication. The primary aim of this study was to analyze the impact of obesity on clinical outcomes and complication rates of patients undergoing bilateral TKA under one anesthetic. Materials and Methods. The clinical outcomes of 133 patients (266 knees) who underwent bilateral TKA between 2013 and 2016 were reviewed. The procedures were performed by three separate surgeons across three major academic institutions. ASA scores, tourniquet time, operative time, blood loss, length of stay, readmission, and postoperative complications were compared between different BMI categories of less than 30 kg/ m2, 30–34.99 kg/ m2, 35–39.99 kg/ m2and above 40 kg/ m2. Results. There were 83 females and 50 males who underwent bilateral TKA identified, with an average age of 60.17 years. The average LOS was 5 days and there was no significant impact of BMI on the length of stay or blood loss. 31 out of 133 patients experienced either a minor or major complication postoperatively (Table 1). Obese patients experienced more complications than non-obese patients. Specifically, patients identified as morbidly obese experienced a complication rate of 44.4%. This was significantly higher than the complication rate in the non-obese (less than 30 kg/ m2) patient cohort, 20.8% (p=.034). Of the 31 complications, 10 patients required a return to the operating room for a manipulation under anesthesia. There was no significant difference in the manipulation rate for the obese and non-obese patient. As BMI increased; postoperative ROM displayed a trend in the negative direction (Table 2). On average, obese patients had significantly higher ASA scores, with only 13.8% of patients with a BMI below 30 assigned an ASA score of 3 in comparison to 50% of patients with a BMI of 40 and above (p= .013) (Table 3). Higher BMI was significantly correlated with longer operative times (p=.002). Conclusion. Similar to numerous unilateral TKA studies in the obese patient, greater complication rates in the obese patient population were noted. The majority of complications that occurred within the time of this study were minor and did not affect the outcome of the procedure. Surgeons should carefully analyze the comorbidities of patients with a BMI above 40 kg/m2 such as cardiac history, diabetes mellitus, and smoking status when considering operating on morbidly obese patients and take steps to address these comorbidities and maximize the patient prior to surgery. For any figures or tables, please contact authors directly

The COVID-19 pandemic has led to unprecedented times worldwide. From lockdowns to masks now being part of our everyday routine, to the halting of elective surgeries, the virus has touched everyone and every part of our personal and professional lives. Perhaps, now more than ever, our ability to adapt, change and persevere is critical to our survival. This year's closed meeting of The Knee Society demonstrated exactly those characteristics. When it became evident that an in-person meeting would not be feasible, The Knee Society leadership, under the direction of President John Callaghan, MD and Program Chair Craig Della Valle, MD created a unique and engaging meeting held on September 10–12, 2020. Special recognition should be given to Olga Foley and Cynthia Garcia at The Knee Society for their flexibility and creativeness in putting together a world-class flawless virtual program. The Bone & Joint Journal is very pleased to partner with The Knee Society to once again publish the proceedings of the closed meeting of the Knee Society. The Knee Society is a United States based society of highly selected members who have shown leadership in education and research in knee surgery. It invites up to 15% international members; this includes some of the key opinion leaders in knee surgery from outside the USA. Each year, the top research papers from The Knee Society meeting will be published and made available to the wider orthopaedic community in The Bone & Joint Journal. The first such proceedings were published in BJJ in 2019. International dissemination should help to fulfil the mission and vision of the Knee Society of advancing the care of patients with knee disorders through leadership, education and research. The quality of dissemination that The Bone & Joint Journal provides should enhance the profile of this work and allow a larger body of surgeons, associated healthcare professionals and patients to benefit from the expertise of the members of The Knee Society. The meeting is one of the highlights of the annual academic calendar for knee surgeons. With nearly every member in attendance virtually throughout the 3 days, the top research papers from the membership were presented and discussed in a virtual format that allowed for lively interaction and discussion. There are 75 abstracts presented. More selective proceedings with full papers will be available after a robust peer review process in 2021, both online and in The Bone & Joint Journal. The meeting commenced with the first group of scientific papers focused on Periprosthetic Joint Infection. Dr Berry and colleagues from the Mayo Clinic further help to clarify the issue of serology and aspirate results to diagnose TKA PJI in the acute postoperative setting. 177 TKA's had an aspiration within 12 weeks and 22 were proven to have PJI. Their results demonstrated that acute PJI after TKA should be suspected within 6 weeks if CRP is ≥81 mg/L, synovial WBCs are ≥8500 cells/μL, and/or synovial neutrophils≥86%. Between 6– 12 weeks, concerning thresholds include a CRP ≥ 32 mg/L, synovial WBC ≥7450, and synovial neutrophils ≥ 84%. While historically the results of a DAIR procedure for PJI have been variable, Tom Fehring's study showed promise with the local delivery of vancomycin through the Intraosseous route improved early results. New member Simon Young contrasted the efficacy of the DAIR procedure when comparing early infections to late acute hematogenous PJI. DAIR failed in 63% of late hematogenous PJIs (implant age>1 year) compared to 36% of early (<1year) PJIs. Dr Masri demonstrated in a small group of patients that those with well-functioning articulating spacers can retain their spacers for over 12 months with no difference in infection from those that had a formal two stage exchange. The mental toll of PJI was demonstrated in a longitudinal study by Doug Dennis, where patient being treated with 2 stage exchange had 4x higher rates of depression compared to patient undergoing aseptic revision. The second session focused on both postoperative issues with regards to anticoagulation and manipulation. Steven Haas demonstrated high complication rates with utilization of anticoagulation for treatment of postoperative pulmonary embolism with modern therapeutic anticoagulation (warfarin, enoxaparin, Xa inhibitors) with the Xa inhibitors demonstrating lower complication rates. Two papers focused on the topic of manipulation. Mark Pagnano presented data on timing of manipulation under anesthesia up to even past 12 months. While gains were modest, a subset of patients did achieve substantial gains in ROM > 20degrees even after 3 months post op. Dr Westrich's study demonstrated no difference in MUA outcomes with either IV sedation or neuraxial anesthesia although the length of stay was shorter in the IV sedation group. Several studies in Session II focused on kinematics and femoral component position. Dr Li's in vivo kinematic study during weightbearing flexion and gait demonstrated that several knees rotated with a lateral pivot motion and not all knees can be described with a single motion character. Dr Mayman and his group utilized a computational knee model to demonstrate that additional distal femoral resection results in increasing levels of mid -flexion instability and cautioned against the use of additional bony resection as the first line for flexion contractures. Using computer navigation, Dr Huddleston's study nicely outlined the variability in femoral component rotation to achieve a rectangular flexion gap utilizing a gap balanced method. The third session opened the meeting on Friday morning. The focus was on unicompartmental knee arthroplasty and the increasing utilization of robotic assisted total knee arthroplasty. David Murray showed using registry data that for patient with higher comorbidities (ASA >3), UKA was safer and more cost effective than TKA while Dr Della Valle's group demonstrated overall lower average healthcare costs in UKA patients compared to TKA in the first 10 years after surgery. Dr Geller assessed UKA survivorship among 3 international registries. While survivorship varied by nation and designs, certain designs consistently had better overall performance. Dr Nunley and his group showed robotic navigation UKA significantly reduced outliers in alignment and overhang compared to manual UKA. Dr Catani's data demonstrated that full thickness cartilage loss should still be considered a requirement for UKA success even with robotic assistance. Despite a high dislocation rate of 4%, Mr Dodd demonstrated high survivorship for lateral UKA despite historical contraindications. The growing evidence for robotics TKA was demonstrated in two studies. Professor Haddad showed less soft tissue injury, reduced bone trauma and improved accuracy or rTKA compared to manual TKA while Dr Gustke single surgeon study showed his rTKA had improved forgotten joint scores and less ligament releasing required for balancing. Despite these finding, Dr Lee's study demonstrated that a robotic TKA could not guarantee excellent pain relief and other factors such a patient expectations and psychological factors play a role. Our fourth session was devoted to machine learning and smart tools and modeling. Dr Meneghini used machine learning algorithms to identify optimal alignment outcomes that correlated with patient outcomes. Several parameters such as native tibial slope, femoral sagittal position and coronal limb alignment correlated with outcomes. Along the same lines, Bozic and coauthors demonstrated that using AI algorithms incorporated with PROM's improved levels of shared decision making and patient satisfaction. Dr Lombardi demonstrated that a mobile patient engagement platform that provided smart phone-based exercise and education was comparable to traditional methods. Dr Mahfouz demonstrated the accuracy of using ultrasound to produce 3D models of the bone compared to conventional CT based strategies and Dr Mahoney showed the valued of a preop 3D model in reproducing more normal knee kinematics. The last two talks of the session focused on some of the positives of the COVID-19 pandemic, namely the embracing of telemedicine by patients and surgeons as demonstrated by Dr Slover and the increasing and far reaching educational opportunities made available to residents and fellows during the pandemic. Session five focused on risk stratification and optimization prior to TKA. Dr O'Connor demonstrated that that the implementation of an optimization program preoperatively reduced length of stay and ED visits, and Charles Nelson's study showed that risk stratification tool can lower complication rates in obese patients undergoing TKA comparable to those that are nonobese. Dr Markel's study demonstrated that those who have preoperative depression and anxiety are at higher risk of complications and readmissions after surgery and these issues should be addressed preoperatively. Interestingly, a study by Dr Callaghan demonstrated that care improvement pathways have not lowered the gap in complications for morbidly obese patients undergoing TKA, Dr Barsoum argued that the overall complication rates were low and this patient cohort had significant gains in PROMS after TKA that would not be experienced if arbitrary cutoff for limited surgery were established. The final session on Friday, Session six, had several well done and interesting studies. There continues to be mounting evidence that liposomal bupivacaine has little effect on managing post-operative pain to warrant its increased use. Bill Macaulay and colleagues showed no change in pain scores, opioid consumption and functional scores when liposomal bupivacaine was discontinued at a large academic medical center. Dr Bugbee importantly demonstrated that a supervised ambulation program reduced falls in the early postoperative period. Several paper on healthcare economics were presented. Rich Iorio showed that stratifying complexity of total joint cases between hospitals with a system can be efficient and cost savings while Dr Jiranek demonstrated in his study that complex TKAs can be identified preoperatively and are associated with prolonged operative time and cost of care and consideration should be given in future reimbursement models to a complexity modifier. Dr Springer, in their evaluation of Medicare bundled payment models, demonstrated that providers and hospitals in historical bundled models that became efficient were penalized in the new model, forcing many groups to drop out and return to a fee for service model. Ron Delanois important work showed that social determinants can have a major negative impact on outcomes following TKA. Our final day on Saturday opened with Session seven, and several interesting paper on metal ions/debris in TKA. Dr Whitesides simulator study showed the absence of scratches and material loss in a ceramic TKA compared with Co-Cr TKA and suggested an advantage to this material in patients with metal sensitivity. Conversely, in a histological study of failed TKA, perivascular lymphocytic infiltration was not associated with worse clinical outcomes or differences in revision in a series of 617 aseptic revisions, 19% of which had PVLI found on histology. The Mayo group and Dr Trousdale however, noted that serum metal ion levels can be helpful in identifying implant failure in a group of revision TKAs, especially those with metallic junctions. Dr Dalury demonstrated nicely that use of maximally conforming inserts did not have a negative effect on implant loosening in a series of 76 revision TKA's at an average follow up of 7 years, while Kevin Garvin and his group showed no difference in end of stem pain between cemented and cementless stems in revision TKA. The final two studies in the session by Bolognesi and Peters respectively showed that metaphyseal cones continue to demonstrate excelled survivorship in rTKA setting despite extensive bone loss. Session eight was highlighted by a large series of revision reported by new member Dr Schwarzkopf, who showed that revision TKA done by high volume surgeons demonstrated better outcomes and lower revision rates compared to surgeon who did less than 18 rTKA's per year. Dr Maniar importantly showed that preoperatively, patients with high activity level and low pain and indicated by a high preop forgotten joint score did poorly following TKA while David Ayers nicely demonstrated that KOOS scores that assess specific postoperative outcomes can predict patient dissatisfaction after TKA. The final paper in this session by Max Courtney showed that the majority of surgical cancellations are due to medical issues, yet a minority of these undergo any intervention specifically for that condition, but they resulted in a delay of 5 months. The first two studies of Session nine focused on polyethylene thickness. Dr Backstein demonstrated no difference in KSS scores, change in ROM and aseptic revision rates based on polyethylene thickness in a series of 195 TKA's. An interesting lab study by Dr Tim Wright showed a surprising consistency in liner thickness choice among varying levels of surgeon experience that did not correlate with applied forces or gap stability estimates. Two studies looked specifically at the issue of tibial loosening and implant design. Nam and colleagues were not able to demonstrate concerning findings for increasing tibial loosening in a tibial baseplate with a shortened tibial keel at short term follow up, while Lachiewicz demonstrated a 19% revision or revision pending rate in 223 cemented fixed bearing ATTUNE TKA at a mean of 30 months. Our final session of the meeting, began with encouraging news, that despite only currently capturing about 40% of TJA's done in the US, the American Joint Replacement Registry data is representative of data in other representative US databases. An interesting study presented by Robert Barrack looked at bone remodeling in the proximal tibia after cemented and cementless TKA of two different designs. No significant difference was noted among the groups with the exception of the cemented thicker cobalt chrome tray which demonstrated significantly more bone mineral density loss. Along the same lines, a study out of Dr Bostrom's lab demonstrated treatment of a murine tibial model with iPTH prevents fibrous tissue formation and enhances bone formation in cementless implants. New Member Jamie Howard showed no difference in implant migration and kinematics of a single radius cementless design using either a measured resection or gap balancing technique and Dr Cushner show no difference in blood loss with cemented or cementless TKA with the use of TKA. The final two studies looked at staging and bilateral TKA's. Peter Sharkey showed that simultaneous TKA's were associated with higher complication compared to staged TKA and that staged TKA with less than a 90-day interval was not associated with higher risk. However, Mark Figgie showed that patients undergoing simultaneous TKA compared to staged TKA, missed 17 fewer days of work. In spite of the virtual nature of the meeting, there were some outstanding scientific interactions and the material presented will continue to generate debate and to guide the direction of knee arthroplasty as we move forwards

Aims

To assess the incidence of radiological lateral osteoarthritis (OA) at 15 years after medial unicompartmental knee arthroplasty (UKA) and assess the relationship of lateral OA with symptoms and patient characteristics.

Aims

The mid-term results of kinematic alignment (KA) for total knee arthroplasty (TKA) using image derived instrumentation (IDI) have not been reported in detail, and questions remain regarding ligamentous stability and revisions. This paper aims to address the following: 1) what is the distribution of alignment of KA TKAs using IDI; 2) is a TKA alignment category associated with increased risk of failure or poor patient outcomes; 3) does extending limb alignment lead to changes in soft-tissue laxity; and 4) what is the five-year survivorship and outcomes of KA TKA using IDI?

Aims

Access to total knee arthroplasty (TKA) is sometimes restricted for patients with severe obesity (BMI ≥ 40 kg/m²). This study compares the cost per quality-adjusted life year (QALY) associated with TKA in patients with a BMI above and below 40 kg/m² to examine whether this is supported.

Aims

Rates of readmission and reoperation following primary total knee arthroplasty (TKA) are under scrutiny due to new payment models, which penalize these negative outcomes. Some risk factors are more modifiable than others, and some conditions considered modifiable such as obesity may not be as modifiable in the setting of advanced arthritis as many propose. We sought to determine whether controlling for hypoalbuminaemia would mitigate the effect that prior authors had identified in patients with obesity.

Aims

Many patients undergoing total knee arthroplasty (TKA) have severe osteoarthritis (OA) in both knees and may consider either simultaneous or staged bilateral TKA. The implications of simultaneous versus staged bilateral TKA for return to work are not well understood. We hypothesized that employed patients who underwent simultaneous bilateral TKA would have significantly fewer days missed from work compared with the sum of days missed from each operation for patients who underwent staged bilateral TKA.

Aims

For many designs of total knee arthroplasty (TKA) it remains unclear whether cemented or uncemented fixation provides optimal long-term survival. The main limitation in most studies is a retrospective or non-comparative study design. The same is true for comparative trials looking only at the survival rate as extensive sample sizes are needed to detect true differences in fixation and durability. Studies using radiostereometric analysis (RSA) techniques have shown to be highly predictive in detecting late occurring aseptic loosening at an early stage. To investigate the difference in predicted long-term survival between cemented, uncemented, and hybrid fixation of TKA, we performed a randomized controlled trial using RSA.

Cementless knee arthroplasty has seen a recent resurgence in popularity due to conceptual advantages, including improved osseointegration providing biological fixation, increased surgical efficiency, and reduced systemic complications associated with cement impaction and wear from cement debris. Increasingly younger and higher demand patients are requiring knee arthroplasty, and as such, there is optimism cementless fixation may improve implant survivorship and functional outcomes.

Compared to cemented implants, the National Joint Registry (NJR) currently reports higher revision rates in cementless total knee arthroplasty (TKA), but lower in unicompartmental knee arthroplasty (UKA). However, recent studies are beginning to show excellent outcomes with cementless implants, particularly with UKA which has shown superior performance to cemented varieties. Cementless TKA has yet to show long-term benefit, and currently performs equivalently to cemented in short- to medium-term cohort studies. However, with novel concepts including 3D-printed coatings, robotic-assisted surgery, radiostereometric analysis, and kinematic or functional knee alignment principles, it is hoped they may help improve the outcomes of cementless TKA in the long-term. In addition, though cementless implant costs remain higher due to novel implant coatings, it is speculated cost-effectiveness can be achieved through greater surgical efficiency and potential reduction in revision costs. There is paucity of level one data on long-term outcomes between fixation methods and the cost-effectiveness of modern cementless knee arthroplasty.

This review explores recent literature on cementless knee arthroplasty, with regards to clinical outcomes, implant survivorship, complications, and cost-effectiveness; providing a concise update to assist clinicians on implant choice.

Cite this article: Bone Jt Open 2021;2(1):48–57.