The use of rotating hinge (RH) prostheses for severe primary as well as revision arthroplasty is widely established. Aim of this study was to investigate long term results of a new RH prosthesis (EnduRo®, B Braun, Germany), which uses carbon-fiber reinforced poly-ether-ether-ketone (CFR PEEK) as a new bearing material, first time used in knee arthroplasty. Fifty-six consecutive patients, who received the EnduRo® RH prosthesis were included in this prospective study: 21 patients (37.5%) received the prosthesis as a primary total knee arthroplasty (TKA) and 35 patients (62.5%) underwent revision total knee arthroplasties (rTKA). Clinical and radiographic examinations were performed preoperatively as well as postoperatively after 3 and 12 months and annually thereafter. Min. Follow up was 7 and mean follow up 9,3 years. Clinical examination included Knee Society Score (KSS), Western Ontario and McMaster Osteoarthritis Index (WOMAC), Oxford Knee Score (OKS), and range of motion (ROM). Competing risk analysis was assessed for survival with respect to indication and failure mode. KSS, WOMAC, OKS, and ROM significantly improved from the preoperative to the follow up investigations (p < 0.0001). There was no difference in clinical outcome between the primary and the revision group. The overall cumulative incidence for revision for any reason was 23.6% and the cumulative incidence for complications associated with failure of the prothesis was 5.6% at 7 years, respectively. Complications occurred more frequently in the revision group (p = 0.002). The evaluated RH prosthesis provided reliable and durable results with a minimum follow-up of 7 years. Prosthesis survival was successful considering the complexity of cases. The use of this RH system in primary patients showed high survival rates. Long-term functional and clinical results proved to be satisfying in both revision and primary cases. No adverse events were associated with the new bearing material CFR-PEEK

Approximately 20% of patients feel unsatisfied 12 months after primary total knee arthroplasty (TKA). Current predictive tools for TKA focus on the clinician as the intended user rather than the patient. The aim of this study is to develop a tool that can be used by patients without clinician assistance, to predict health-related quality of life (HRQoL) outcomes 12 months after total knee arthroplasty (TKA). All patients with primary TKAs for osteoarthritis between 2012 and 2019 at a tertiary institutional registry were analysed. The predictive outcome was improvement in Veterans-RAND 12 utility score at 12 months after surgery. Potential predictors included patient demographics, co-morbidities, and patient reported outcome scores at baseline. Logistic regression and three machine learning algorithms were used. Models were evaluated using both discrimination and calibration metrics. Predictive outcomes were categorised into deciles from 1 being the least likely to improve to 10 being the most likely to improve. 3703 eligible patients were included in the analysis. The logistic regression model performed the best in out-of-sample evaluation for both discrimination (AUC = 0.712) and calibration (gradient = 1.176, intercept = -0.116, Brier score = 0.201) metrics. Machine learning algorithms were not superior to logistic regression in any performance metric. Patients in the lowest decile (1) had a 29% probability for improvement and patients in the highest decile (10) had an 86% probability for improvement. Logistic regression outperformed machine learning algorithms in this study. The final model performed well enough with calibration metrics to accurately predict improvement after TKA using deciles. An ongoing randomised controlled trial (ACTRN12622000072718) is evaluating the effect of this tool on patient willingness for surgery. Full results of this trial are expected to be available by April 2023. A free-to-use online version of the tool is available at . smartchoice.org.au.

Aim. One of the most severe complications of primary total knee arthroplasty (TKA) is periprosthetic joint infection (PJI). Nowadays, the use of antibiotic-loaded cement for prevention of infection is still controversial. The aim of the present study is to evaluate the use of an antibiotic-loaded cement to reduce the infection rate in primary total knee arthroplasty. Method. Prospective randomized study, with 2893 cemented total knee arthroplasties performed between 2005 and 2010 in our institution. Two different groups were formed depending on which bone cement was used, without antibiotic (the control group) or loaded with erythromycin and colistin (the study group). All patients received the same systemic prophylactic antibiotics. The patients were followed for a minimum of twelve months. The rate of infection was analyzed according to the criteria of the Centers for Disease Control and Prevention (CDC). Results. In 1452 patients the prosthetic components were fixed using bone cement without antibiotic and in 1441 patients bone cement loaded with erythromycin and colistin was used. There were no differences between both groups in terms of demographic data (age, sex and BMI), either in operating time (p>0,05). The rate of infection was similar in both groups, being 2,0% (n=29) in the control group and 1,7% in the study group (p=0,58) at 8,7 years (SD 5,1) of follow up. In terms of prosthetic revision due to any cause (infected or aseptic), there wasn't differences between groups, performing a total of 61 revision arthroplasties in control group and 68 in study group (p>0,05). Moreover, we analyzed the erythromycin resistance rate, being no differences between both groups (p=0.6). Conclusions. The use of erythromycin and colistin-loaded bone cement in total knee arthroplasty did not lead to a decrease in the rate of infection when systemic prophylactic antibiotics were used, a finding that suggests that its use would not be indicated in the general population

The aim of this study was to determine the incidence, annual trend, perioperative outcomes, and identify risk factors of early-onset (≤ 90 days) deep surgical site infection (SSI) following primary total knee arthroplasty (TKA) for osteoarthritis. Risk factors for early-onset deep SSI were assessed. We performed a retrospective population-based cohort study using prospectively collected patient-level data from several provincial administrative data repositories between January 2013, and March 2020. The diagnosis of early-onset deep SSI was based on published Centre for Disease Control/National Healthcare Safety Network (CDC/NHSN) definitions. The Mann-Kendall Trend Test was used to detect monotonic trends in early-onset deep SSI rates over time. The effects of various patient and surgical risk factors for early-onset deep SSI were analyzed using multiple logistic regression. Secondary outcomes were 90-day mortality and 90-day readmission. A total of 20,580 patients underwent primary TKA for osteoarthritis. Forty patients had a confirmed deep SSI within 90-days of surgery representing a cumulative incidence of 0.19%. The annual infection rate did not change over the 7-year study period (p = 0.879). Risk factors associated with early-onset deep SSI included blood transfusions (OR, 3.93 [95% CI 1.34-9.20]; p=0.004), drug or alcohol abuse (OR, 4.91 [95% CI 1.85-10.93]; p<0.001), and surgeon volume less than 30 TKA per year (OR, 4.45 [1.07-12.43]; p=0.013). Early-onset deep SSI was not associated with 90-days mortality (OR, 11.68 [0.09-90-58]; p=0.217), but was associated with an increased chance of 90-day readmission (OR, 50.78 [26.47-102.02]; p<0.001). This study establishes a reliable baseline infection rate for early-onset deep SSI after TKA for osteoarthritis through the use of a robust methodological process. Several risk factors for early-onset deep SSI are potentially modifiable or can be optimized prior to surgery and be effective in reducing the incidence of early-onset SSI. This could guide the formulation of provincial screening programs and identify patients at high risk for SSI

Primary hip and knee joint replacements in Canada have been estimated to cost over $1.4 billion dollars annually, with revision surgery costing $177 million. The most common cause of revision arthroplasty surgery in Canada is infection. Periprosthetic joint infections (PJIs) are a devastating though preventable complication following arthroplasty. Though variably used, antibiotic laden bone cement (ALBC) has been demonstrated to decrease PJIs following primary total knee arthroplasty (TKA). Unfortunately, ALBC is costlier than regular bone cement (RBC). Therefore, the aim of this study was to determine if the routine use of ALBC in primary TKA surgery is a cost-effective practice from the perspective of the Canadian healthcare system. A decision tree was constructed using a decision analysis software (TreeAge Software, Williamstown, Massachusetts) to a two-year time horizon comparing primary TKA with either ALBC or RBC from the perspective of a single-payer healthcare system. All costs were in 2020 Canadian dollars. Health utilities were in the form of quality adjusted life years (QALYs). Model inputs for cost were derived from regional and national databases. Health utilities and probability parameters were derived from the latest literature. One-way deterministic sensitivity analysis was performed on all model parameters. The primary outcome of this analysis was an incremental cost-effectiveness ratio (ICER) with a willingness-to-pay (WTP) threshold of $50,000 per QALY. Primary TKA with ALBC (TKA-ALBC) was found to be more cost-effective compared to primary TKA with RBC (TKA-RBC). More specifically, TKA-ALBC dominated TKA-RBC as it was less costly on the long term ($11,160 vs. $11,118), while providing the same QALY (1.66). The ICER of this cost-utility analysis (CUA) was $-11,049.72 per QALY, much less than the WTP threshold of $50,000 per QALY. The model was sensitive to costs of ALBC-TKA as well as the probability of PJI following ALBC-TKA and RBC-TKA. ALBC ceased to be cost effective once the cost of ALBC was greater than $223.08 CAD per bag of cement. The routine use of ALBC in primary TKA is a cost-effective practice in the context of the Canadian healthcare system as long as the cost of ALBC is maintained at a reasonable price and the published studies to-date keep supporting the efficacy of ALBC in decreasing PJI following primary TKA. Further, this analysis is very conservative, and ALBC is likely much more cost-effective than presented. This is due to this model's revision surgery cost parameter being based on the average cost of all revision TKA surgery in Canada, regardless of etiology. Considering many PJIs require two-stage revisions, the cost parameter used in this analysis for revision surgery is an underestimate of true cost. Ultimately, this is the first cost-effectiveness study evaluating this topic from the perspective of the Canadian healthcare system and can inform future national guidelines on the subject matter

Aim. Strenuous efforts to minimize postoperative infection rates have been made, including the Swedish nation-wide initiative Prosthesis Related Infections Shall be Stopped (PRISS). The aim of this study was to calculate the incidence rate of periprosthetic joint infections (PJI) following primary total knee arthroplasty (TKA) before and after PRISS. Method. All 45,438 primary TKAs registered in the Swedish knee arthroplasty register (SKAR) during 2007–2008 and 2012–2013 were included. Matched data on antibiotic prescriptions were obtained from the Swedish Prescribed Drug Register (SPDR). All patients with ≥28 days of continuous antibiotic treatment within 2 years of primary surgery had their medical charts reviewed to identify cases of PJI. Results. 644 PJIs were identified, equaling a 2-year cumulative incidence rate of 1.42% (95% CI: 1.31–1.53). The incidence rate was 1.41% before PRISS and 1.43% after. Diagnosis was made within 30 days of primary TKA in 52%, and within 90 days in 73% of the cases. 603 cases were reoperated. Debridement with exchange of the insert was performed in 32.1% and 62.5% of cases before and after PRISS respectively. Conclusions. No reduction in cumulative PJI incidence was seen after the PRISS initiative

Aim. Whether laminar airflow (LAF) in the operating room (OR) is effective for decreasing periprosthetic joint infection (PJI) following total joint arthroplasty (TJA) remains a clinically significant yet controversial issue. This study investigated the association between operating room ventilation systems and the risk of PJI in TJA patients. Method. We performed a retrospective observational study on consecutive patients undergoing primary total knee arthroplasty (TKA) and total hip arthroplasty (THA) from January 2013-September 2017 in two surgical facilities within a single institution, with a minimum 1-year follow-up. All procedures were performed by five board-certified arthroplasty surgeons. The operating rooms at the facilities were equipped with LAF and turbulent ventilation systems, respectively. Patient characteristics were extracted from clinical records. PJI was defined according to Musculoskeletal Infection Society criteria within 1-year of the index arthroplasty. A multivariate logistic regression model was performed to explore the association between LAF and risk of 1-year PJI, and then a sensitivity analysis using propensity score matching (PSM) was performed to further validate the findings. Results. A total of 6,972 patients (2,797 TKA, 4,175 THA) were included. The incidence of PJI within 1 year for patients from the facility without laminar flow was similar at 0·4% to that of patients from the facility with laminar flow at 0·5%. In the multivariate logistic regression analysis, after all confounding factors were taken into account, the use of LAF was not significantly associated with reduction of the risk of PJI. After propensity score matching, there was no significant difference in the incidence of PJI within 1 year for patients between the two sites. Conclusions. The use of LAF in the operating room was not associated with a reduced incidence of PJI following primary TJA. With an appropriate perioperative protocol for infection prevention, LAF does not seem to play a protective role in PJI prevention

Introduction. Surgeons commonly resect additional distal femur during primary total knee arthroplasty (TKA) to correct a flexion contracture to restore range of motion and knee function. However, the effect of joint line elevation on the resulting TKA kinematics including frontal plane laxity is unclear. Thus, our goal was to quantify the effect of additional distal femoral resection on passive extension and mid-flexion laxity. Methods. Six computational knee models with capsular and collateral ligament properties specific to TKA were developed and implanted with a contemporary posterior-stabilized TKA. A 10° flexion contracture was modeled by imposing capsular contracture as determined by simulating a common clinical exam of knee extension and accounting for the length and weight of each limb segment from which the models were derived (Figure 1). Distal femoral resections of 2 mm and 4 mm were simulated for each model. The knees were then extended by applying the measured knee moments to quantify the amount of knee extension. The output data were compared with a previous cadaveric study using a two-sample two-tailed t-test (p<0.05) [1]. Subsequently, varus and valgus torques of ±10 Nm were applied as the knee was flexed from 0° to 90° at the baseline, and after distal resections of 2 mm, and 4 mm. Coronal laxity, defined as the sum of varus and valgus angulation in response to the applied varus and valgus torques, was measured at 30° and 45°of flexion, and the flexion angle was identified where the increase in laxity was the greatest with respect to baseline. Results. With 2 mm and 4 mm of distal femoral resection, the knee extended an additional 4°±0.5° and 8°±0.75°, respectively (Figure 2). No significant difference was found between the extension angle predicted by the six models and the results of the cadaveric study after 2 mm (p= 0.71) and 4 mm (p= 0.47). At 2 mm resection, mean coronal laxity increased by 3.1° and 2.7° at 30° and 45°of flexion, respectively. At 4 mm resection, mean coronal laxity increased by 6.5° and 5.5° at 30° and 45° of flexion, respectively (Figures 3a and 3b). The flexion angle corresponding to the greatest increase in coronal laxity for 2 mm of distal resection occurred at 22±7° of flexion with a mean increase in laxity of 4.0° from baseline. For 4 mm distal resection, the greatest increase in coronal laxity occurred at 16±6° of flexion with a mean increase in laxity of 7.8° from baseline. Conclusion. A TKA computational model representing a knee with preoperative flexion contracture was developed and corroborated measures from a previous cadaveric study [1]. While additional distal femoral resection in primary TKA increases passive knee extension, the consequent joint line elevation induced up to 8° of additional coronal laxity in mid-flexion. This additional midflexion laxity could contribute to midflexion instability; a condition that may require TKA revision surgery. Further studies are warranted to understand the relationship between joint line elevation, midflexion laxity, and instability. For any figures or tables, please contact the authors directly

Surgical fixation of tibial plateau fractures in elderly patients with open reduction and internal fixation (ORIF) provides inferior outcomes compared to younger patients. Primary total knee arthroplasty (TKA) may be of benefit in patients with pre-existing arthritis, marked osteopenia, or severe fracture comminution. Rationale for primary TKA includes allowing early mobility in hopes of reducing associated complications such as deconditioning, postoperative pneumonia, or venous thromboembolism, and reducing post-traumatic arthritis which occurs in 25% to 45% of patients and requires revision TKA in up to 15%. Subsequent revision TKA has been shown to have significantly worse outcomes than TKA for primary osteoarthritis. This systematic review sought to elicit the clinical outcomes and peri-operative complication rates following primary TKA for tibial plateau fractures. A comprehensive search of MEDLINE, Embase, and PubMed databases from inception through March 2018 was performed in accordance with PRISMA guidelines. Two reviewers independently screened papers for inclusion and identified studies featuring perioperative complications and clinical outcomes following primary TKA for tibial plateau fractures. Studies were included for final data analysis if they met the following criteria: (1) studies investigating TKA as the initial treatment for tibial plateau fractures, (2) patients must be ≥ 18 years old, (3) have a minimum ≥ 24-month follow-up, and (4) must be published in the English language. Case series, cohort, case-control, and randomized-control trials were included. Weighted means and standard deviations are presented for each outcome. Seven articles (105 patients) were eligible for inclusion. The mean age was 73 years and average follow-up was 39 months. All-cause mortality was 4.75% ± 4.85. The total complication rate was 15.2% ± 17.3% and a total of eight patients required revision surgery. Regarding functional outcomes, the Knee Society score was most commonly reported. The average score on the knee subsection was 85.6 ± 5.5 while the average function subscore was 64.6 ± 13.7. Average range of motion at final follow-up was 107.5° ± 10°. Total knee arthroplasty for the treatment of acute tibial plateau fractures is enticing to allow early mobility and weightbearing. However, complication rates remain high. Functional outcomes are similar to patients treated with ORIF or delayed arthroplasty. Given these findings, surgeons should be highly selective in performing TKA for the immediate treatment of tibial plateau fractures

Background. Patterns of opioid overprescribing following arthroplasty likely developed given that poor pain control can diminish patient satisfaction, delay disposition, and lead to complications. Recently, interventions promoting responsible pain management have been described however most of the existing literature focuses on opioid naive patients. We sought to describe the effect of an educational intervention on prescribing for opioid tolerant patients. Methods. As the start to a quality improvement initiative to reduce opioid overprescribing, a departmental grand rounds was conducted. Prescribing data, for the year before and after this intervention, were retrospectively collected for all opioid tolerant patients undergoing primary total knee arthroplasty (TKA) and primary total hip arthroplasty (THA). Opioid prescribing data was standardized to mean morphine equivalents (MME). Segmented time series regression was utilized to estimate the change in opioid prescribing associated with the intervention. Results. A total of 508 opioid tolerant patients underwent TKA and 342 opioid tolerant patients underwent THA at our institution during the study period. The intervention was associated with a statistically significant decrease of 468 mean MME (23%) from 2,062 to 1,594 (P=0.005)in TKA patients and 594 mean MME (28%) from 2,159 to 1,565 (P=0.003) in THA patients. There were no readmissions for pain control during the study period. Conclusions. This study demonstrates an educational intervention is associated with decreased opioid prescribing to opioid tolerant arthroplasty patients. While the effective management of these patients is challenging, surgeon education should be a key focus to optimizing their care. Level of Evidence. Level III, retrospective cohort study. Keywords. Primary Arthroplasty; Opioid Tolerant; Analgesics, Opioid; Practice Patterns, Physicians; Quality Improvement; Pain, Postoperative

Introduction/Aim. Outcomes for guided motion primary total knee arthroplasty (TKA) in obese patients are unknown. Materials and Methods. 1,684 consecutive patients underwent 2,059 primary TKAs with a second-generation guided motion implant (Journey II Bi-Cruciate Stabilized Knee System, Smith & Nephew, Inc., Memphis) between 2011–2017 at three European and seven US sites. Results. Of 2,003 (97.3%) TKAs in 1,644 patients with BMI data: average age 64.5 years; 58.4% females; average BMI 32.5 kg/m. 2. ;13.4% had BMI ≥ 40 kg/m. 2. Subjects with BMI ≥ 40 kg/m. 2. had longest length of hospital stay (LOS) at European sites; LOS similar at US sites. Subjects with BMI ≥ 40 kg/m. 2. (P=0.0349) had longest surgery duration. BMI ≥ 40 kg/m. 2. had more re-hospitalizations or post-TKA reoperations than BMI < 40 kg/m. 2. (12.7% and 9.2% at five-year post-TKA, P<.0495). 62 TKAs were revised (3.39/100 TKA at five years) with no differences in revision risk between groups. 17 (27.4%) revisions involved femoral or tibial component removal; 45 (72.6%) involved tibial insert or patellar component removal only with revision risk similar between groups. Discussion. Our results corroborate literature-reported revision outcomes of standard TKAs in obese patients. Conclusion. Surgery duration and long-term complication rates are higher in patients with BMI ≥ 40 kg/m. 2. , but device revision risk is not elevated

Up to 20 percent of patients remain dissatisfied after primary total knee arthroplasty (TKA) surgery. Understanding the reasons for dissatisfaction post TKA may allow for better patient selection and optimized treatment for those who remain dissatisfied. The association between function, mobility and satisfaction are not well understood. The purpose of this study was to investigate the association between post-TKA satisfaction and i) pre-operative, ii) post-operative, and iii) change in knee joint function during gait. Thirty-one patients scheduled to receive primary TKA for knee osteoarthritis (OA) diagnosis were recruited and visited the Dynamics of Human Motion laboratory for instrumented walking gait analysis (using a synchronized NDI Optotrak motion capture system and AMTI force platforms in the walkway) at two time points, first within the week prior to their surgery, and second at approximately one year after surgery. At their post-operative visit, patients were asked to indicate their satisfaction with their knee prosthesis on a scale from zero to 100, with zero being totally unsatisfied and 100 being completely satisfied. Knee joint mechanics during gait at both time points were characterized by discriminant scores, the projection of their three-dimensional knee angles and moments during gait onto an existing discriminant model that was created to optimize separation of severe knee OA and healthy asymptomatic gait patterns. This discriminant model was created using data from 73 healthy participants and 73 with severe knee OA, and includes the magnitude and pattern features (captured with principal component analysis) of the knee adduction and flexion moment, and the magnitude of the knee flexion angle during gait. Larger discriminant scores indicate improved function toward healthy patterns, and smaller scores indicate more severe function. Associations between post-operative satisfaction and pre, post and change in discriminant scores were examined using Pearson correlation analyses. We also examined associations between satisfaction and pre-operative BMI, EQ5D and Oxford 12 scores, as well as changes in these scores from pre to post-TKA. Discriminant scores representing knee joint function during gait significantly improved on average after surgery (P =0.05). While overall knee joint function improved after primary TKA surgery, the amount of improvement in function was not reflected in post-operative patient satisfaction. However, the pre-operative function of the patient was negatively associated with satisfaction, indicating that patients with higher pre-operative function are overall less satisfied with their TKA surgery, regardless of any functional improvement due to the surgery. Interestingly, the only significant association with post-operative satisfaction was knee joint function, and the relationship between function and patient satisfaction following TKA appears to relate only to the baseline functional state of the patient, and not with functional improvement. This suggests that dissatisfaction post-surgery is more likely reflecting the unmet expectations of a higher functioning patient, and has implications for the need for improved understanding of pre-operative patient functional variability in TKA triage and expectation management

Introduction. The constitutional knee anatomy in the coronal plane includes the distal femoral joint line obliquity (DFJLO) which in most patients is in slight valgus positioning. Despite this native anatomy, the mechanical positioning of the femoral component during primary total knee arthroplasty (TKA) often ignores the native DFJLO opting to place the femur in a set degree of valgus that varies upon the practitioner's practice and experience. Unfortunately, this technique is likely to generate high rate of distal lateral femoral overstuffing. This anatomical mismatch might be a cause of anterior knee pain and therefore partly explain the adverse functional outcomes of mechanically aligned (MA) TKA. Our study aims at assessing the relationship between constitutional knee anatomy and clinical outcomes of MA TKA. We hypothesized that a negative relationship would be found between the constitutional frontal knee deformity, the distal femoral joint line obliquity, and functional outcomes of MA TKA with a special emphasize on patellofemoral (PF) specific outcomes. Methods. One hundred and thirteen patients underwent MA TKA (posterior-stabilized design) for primary end-stage knee osteoarthritis. They were prospectively followed for one year using the New KSS 2011 and HSS Patella score. Residual anterior knee pain was also assessed. Knee phenotypes using anatomical parameters (such as HKA, HKS, DFJLO and LDFA (Lateral distal femoral angle)) were measured from preoperative and postoperative lower-limb EOS® images (Biospace, Paris, France). We assessed the relationship between the knee anatomical parameters and the functional outcome scores at 1 year postoperatively. Results. We investigated four groups according to the preoperative obliquity of the distal femur and HKA. The group with high DFJLO and varus knee deformity demonstrated lower HSS scores (drop>10%, p=0.03) and higher rate of anterior knee pain (p=0.03). Higher postoperative variation of LDFA was associated with lower HSS scores (r = −0.2367, p=0.03) and with higher preoperative DFJLO (p=0.0001) due to the MA technique. Knee phenotypes with LDFA<87° presented higher risk of variation of LDFA. No correlation was found using New KSS 2011 outcomes at one-year follow-up. Discussion/Conclusion. Disregard of the constitutional knee anatomy (LDFA and DFJLO) when performing a MA TKA may generate a non-physiologic knee kinematics that impact patellofemoral outcomes and resulting in residual anterior knee pain. While these results are restricted to modern posterior-stabilized TKA design, recent in silico and in vitro studies supported the negative effect of the lateral overstuffing of the femoral component in the coronal plane during knee flexion. This study provides further evidence that suggest patient-specific anatomical considerations are needed to optimize component position and subsequent outcomes following primary TKA. Additional studies are needed to integrate the rotational status of the femoral component in this analysis. For any figures or tables, please contact authors directly

INTRODUCTION. Over the past 40 years of knee arthroplasty, significant advances have been made in the design of knee implants, resulting in high patient satisfaction. Patellar tracking has been central to improving the patient experience, with modern designs including an optimized Q-angle, deepened trochlear groove, and thin anterior flange.[1–4] Though many of today's femoral components are specific for the left and right sides, Total Joint Orthopedics’ (TJO) Klassic® Knee System features a universal design to achieve operating room efficiencies while providing all the advancements of a modern knee. The Klassic Femur achieves this through a patented double Q-angle to provide excellent patellar tracking whether implanted in the left or the right knee (Figure 1). The present study examines a prospective cohort of 145 consecutive TKA's performed using a modern universal femur and considers patients’ pre- and post-operative Knee Society Clinical Rating System score (KSS). METHODS AND MATERIALS. 145 primary total knee arthroplasties (TKA) were performed during the study using a measured resection technique with a slope-matching tibial cut for all patients. The posterior cruciate ligament (PCL) was sacrificed to accommodate an ultra-congruent polyethylene insert. The distal femur was cut at five degrees (5°) valgus; the tibia was resected neutral (0°) alignment for valgus legs and in two degrees (2°) of varus for varus alignment. The patella was resurfaced for all patients. Patients were followed annually for up to 46 months and were evaluated using the KSS score on a 200-point scale. RESULTS. The final study group comprised 127 primary TKAs. The average age was 68 years (51–90) with 45 males and 68 females. The average weight was 110kg (range: 75–151kg) for men and 88kg (range: 50–129kg) for women. One patient deceased during the follow-up period, four required manipulation under anesthesia, and two required revision for periprosthetic joint infection. There were no failures due to patellar maltracking. No special soft tissue releases were required in any patient. Average pre-operative knee score was 107, improving to 182 at average follow-up of 41 months (36–46 months). Results are summarized in Table 1. DISCUSSION. The improvement in patient clinical experience demonstrates that a universal femoral design can achieve excellent results if it incorporates modern technologies. A double Q-angle design with a deepened trochlear groove and a thin anterior flange appears to provide excellent patellar tracking for all patients in this cohort. This study is limited to the experience of a single institution. Further study would improve the extensibility of these findings. It does show, however, that a femur using a universal design with modern patellar tracking can improve patient satisfaction with their knee following TKA. For any figures or tables, please contact the authors directly

Introduction. Postoperative nausea and vomiting (PONV) is a common occurrence following total joint arthroplasty, and can result in patient discomfort, delayed discharge, and decreased patient satisfaction. Carbohydrate loading as part of the Enhanced Recovery after Surgery (ERAS) protocol has gained popularity, and has been shown to minimize postoperative nausea, vomiting, pain, and lead to accelerated recovery and better overall outcome following abdominal surgery. This study aims to investigate the effects of preoperative carbohydrate-rich drinks on PONV following primary total knee arthroplasty (TKA). Methods. Patients undergoing primary TKA at one institution were enrolled randomly assigned to one of three groups: Group 1 received preoperative carbohydrate-rich drink, Group 2 received placebo water drink of similar appearance and taste, and Group 3 did not receive a drink (control). All healthcare personnel and patients (group 1 and 2) were blinded to group allocation. We compared rate of postoperative nausea, vomiting, length of stay (LOS), and opiate consumption (morphine equivalents, meq). We also reviewed visual analog scale (VAS) pain scores and serum glucose at 0–4 hours, 4–12 hours, and 12–24 hours postoperatively. Results. 229 eligible patients were enrolled and randomized. 79 patients were later excluded due to reasons precluding appropriate participation. 150 patients were included for final analysis, with 50 patients in Group 1, 48 patients in Group 2, and 52 patients in Group 3. The demographics and comorbid conditions known to increase risk of nausea and vomiting were similar between the groups. Rate of vomiting was not statistically significant across groups; group 1 (6%, 3/50), group 2 (13%, 6/48), group 3 (8%, 4/52), p=0.51. Rate of requiring antiemetic medication in group 1 (30%, 15/50) did not differ significantly from group 2 (27%, 13/48) and group 3 (40%, 21/52), p=0.32. Average LOS was not different in group 1 (32 hours) compared to group 2 (32.5 hours) and group 3 (32 hours), p=0.79. Average postoperative opiate consumption for group 1 (57.0 meq) was not statistically different from group 2 (61.3) or group 3 (61.0), p=0.91. Pain VAS scores and serum glucose measurements did not differ between groups for all three time periods (p>0.05). There was no difference in reported adverse events between groups. Conclusion. There appears to be no significant difference in PONV, antiemetic requirements, LOS, pain VAS scores, serum glucose measurements, and opiate consumption in patients receiving preoperative carbohydrate-rich drink prior to primary TKA. Preoperative carbohydrate-rich drinks are safe, however, their utility in the setting of arthroplasty does not yet demonstrate clinical benefit. Continued investigation is required. Summary. This is a prospective, randomized, double-blind, placebo-controlled trial investigating the effect of preoperative carbohydrate-rich drinks on postoperative nausea and vomiting following primary total knee arthroplasty. For any figures or tables, please contact authors directly

INTRODUCTION. In patients presenting with significant ligamentous instability/insufficiency and/or significant varus/valgus deformity of the knee, reproduction of knee alignment and soft tissue stability continues to be a difficult task to achieve. These complex primary total knee arthroplasty (TKA) candidates generally require TKA systems incorporating increasing levels of constraint due to the soft-tissue and/or bone deficiencies. In addition, achievement of “normal” gap symmetry through physiologic kinematics is challenging due to the complexity of the overall correction. Advancements in TKA design have not fully addressed the negative consequences of the increased forces between the degree of component constraint, the femoral box, and the tibial post. The purpose of this early feasibility study was to introduce the design characteristics of a primary TKA system that incorporates progressive constraint kinematics using a low profile trapezoidal femoral box, and to assess the short-term clinical and radiographic results of this patient cohort. METHODS. We retrospectively evaluated 22 consecutive, non-selected, complex primary TKA patients with a minimum of 3-years follow-up and varus deformity of > 20 degrees or valgus deformity of >15 degrees. The Progressive Constraint Kinematics® Knee System (PCK, MAXX Orthopedics, Norristown, PA) was used and provides a variable constraint profile, from high constraint in extension to less constraint in flexion through a novel trapezoidal femoral box. We evaluated patient demographics, pre- and post-operative serial radiography, range of motion (ROM), and total Knee Society Score (KSS – total score). General descriptive statistics and paired t-Test to assess the difference between means at p <0.05 level of significance. RESULTS. The average time to most recent follow-up was 40.5 ±3.5 months (range: 36.0 to 44.0 months). The PCK knee system had 100% survival rate at the most recent follow-up, with no reports of adverse events, subsequent corrective surgery, or revision. The average total KSS improved from 72.7 ±3.2 (range: 68 to 81) pre-operatively to 92.3 ±2.1 (range: 88 to 96) post-operatively (p < 0.001). Full post-operative arc of motion was 0 – 130° and there was no radiographic evidence of composite degradation, aseptic loosening or component malalignment. DISCUSSION/CONCLUSION. The PCK Knee System utilizes a trapezoidal shaped femoral box, where the narrower end is located anteriorly, allowing a valgus/varus tilt of 1–4 degrees and internal/external rotation of 2–7 degrees during flexion, while maintaining necessary soft-tissue constraint during extension. This variable constraint profile allows for fully tensed collaterals in extension, with a slight reduction in collateral tension through flexion. Furthermore, the combination of the condylar anatomy, trapezoidal femoral box and tibial post allows for adequate clearance through full flexion, while facilitating slightly progressive increases in tilt and rotation, thereby maintaining knee kinematics while dampening forces transmitted through the prosthetic composite. From this feasibility study we report promising short-term clinical and radiographic results in the absence of biomechanical failure in complex primary TKA cases. We recommend continuation of the use and further research of the PCK Knee System for complex primary TKA with the ultimate goal of further determining cost effectiveness and intermediate to long-term clinical relevance

Aim. Prosthetic Joint Infection (PJI) remains one of the leading cause for revision arthroplasty. 1,2. Early recognition and appropriate initial treatment of early PJI with debridement, antibiotics and implant retention (DAIR) can eradicate infection on first attempt and prevent implant failure. We evaluated the outcome after one year of patients who were treated for an early PJI after primary total knee arthroplasty (TKA) or total hip arthroplasty (THA) with DAIR. Furthermore, we determined preoperative infection markers, microbiology, and treatment factors related to treatment failure after DAIR procedure. Method. A retrospective cohort study was assembled with 91 patients undergoing DAIR after primary TKA or THP with a high suspicion of an early PJI. For all patients intraoperative cultures were obtained. Records were reviewed for demographic details, preoperative laboratory results, microbiological data, given treatment and postoperative follow-up. The primary outcome measure was infection-free implant survival at one year. Repeated DAIR was not considered as treatment failure. Results. Following DAIR in early PJI the rate of infection-free implant survival was 83% (95% confidence intervals (CI) 79 to 91) at one year follow-up, including patients with multiple DAIR procedures. Univariate analysis indicate a higher failure rate in early PJI caused by Enterococcus faecalis (p=0.04). Multivariate analysis showed that a high C-reactive protein level (CRP >100) (odds ratio 7.5, 95% CI [1.4–39.7]) and multiple debridement procedures (≥2) (p=0.004, odds ratio 8.5, 95%CI [2.1–34.3]) were independently associated with treatment failure. Conclusions. Significantly elevated preoperative serum inflammatory markers may indicate difficult-to-treat, fulminant infections. The winning team in the eradication of an early PJI on first attempt and prevent implant failure is adequate debridement and appropriate empiric antibiotics. To improve treatment success and prevent the need for multiple debridement procedures it is important to use the adequate debridement technique and to have knowledge about local bacterial resistance patterns. Inadequate use of debridement and/or antibiotics can contribute to treatment failure in early PJIs and consequently in saving the affected joint arthroplasty

Radiographic assessment of component rotation has been impossible without using computed tomography or magnetic resonance imaging. The purpose of the present study was to assess the rotational alignment of the femoral component using plane radiography. Eighty-three patients from 89 knees who underwent primary total knee arthroplasty (TKA) were evaluated radiographically before and after surgery using kneeling view, a postero-anterior projection vertical to the tibia at 70 to 80° flexion of the knee. In this view, the transepicondylar axis and posterior condylar line can be seen. The condylar twist angle was 5.7±1.6° preoperatively and 2.6±0.9° postoperatively. The external rotation of the femoral component was 3.2±1.1°. Plane kneeling view radiographs taken before and after TKA can be used to assess the rotational alignment of the femoral component. Axial images of patellofemoral articulation were then superimposed to the kneeling view images along the outline of the femoral component. Combination of kneeling view and axial view can demonstrate the relationship between the rotational alignment of the femoral component and the patellofemoral joint after TKA

Introduction. Fifteen percent of the primary total knee arthroplasties (TKA) fails within 20 years. Among the main causes for revision surgery are instability and patellofemoral pain. Currently, the diagnostic pathway requires various diagnostic techniques to reveal the original cause for the failed knee prosthesis and is therefore time consuming and inefficient. Accordingly, there is a growing demand for a diagnostic tool that is able to simultaneously visualize soft tissue structures, bone and TKA. Magnetic resonance imaging (MRI) is capable of visualising all the structures in the knee although a trade- off needs to be made between metal artefact reducing capacities and image quality. Low-field MRI (0.25T) results in less metal artefacts and a lower image quality compared with high-field MRI (1.5T). The aim of this study is to develop a MRI imaging guide to image the problematic TKA and to evaluate this guide by comparing low-field and high-field MRI on a case study. Method. Based on literature and current differential diagnostic pathways a guide to diagnose patellofemoral pain, instability, malposition and signs of infection or fracture with MRI was developed. Therefore, methods as Insall Salvati, patellar tilt angle and visibility of fluid and soft tissues were chosen. Visibility was scored on a VAS scale from 0 to 100mm (0mm zero visibility, 100mm excellent visibility). Subsequently, this guide is used to analyse MRI scans made of a volunteer (female, 61 years, right knee) with primary TKA (Biomet, Zimmer) in sagittal, coronal and transversal direction with a FSE PD metal artefact reducing (MAR) sequence (TE/TR 12/1030ms, slice thickness 4.0mm, FOV 260×260×120mm. 3. , matrix size 224×216) on low-field MRI (Esaote G-scan Brio, 0.25T) and with a FSE T. 1. -weighted high bandwidth MAR sequence (TE/TR 6/500ms, slice thickness 3.0mm, FOV 195×195×100mm. 3. , matrix size 320×224) on high-field MRI (Avanto 1.5T, Siemens). Scans were analysed three times by one observer and the intra observer reliability was calculated with a two-way random effects model intra class correlation coefficient (ICC). Results. Due to less metal artefacts on the low-field MRI scans the angle, distance and ratio measurements were more consistent: Insall Salvati low-field 0.97–0.99, Insall Salvati high-field 1.05–1.12, patellar tilt angle low-field 2.1–2.8°, patellar tilt angle high-field 2.4–7.6°. Over all, the VAS scores are higher on the high-field MRI scans; VAS medial collateral ligament high-field 26–45, VAS medial collateral ligament low-field 24–34, VAS popliteus tendon high-field 15–27, VAS popliteus tendon low-field 2–7. The ICC values of the VAS scores, angle measurements and ratio measurements were excellent, ICC > 0.9. The ICC values of the distance measurements were moderate, ICC > 0.6. Conclusion. MRI offers possibilities to simultaneously differentiate underlying causes of the failed knee prosthesis. The structures of interest were more clearly visible on the high-field MRI scans due to higher image contrast. The angle, distance and ratio measurements were more consistent on the low-field MRI scans due to less metal artefacts. Further research should focus on a larger group of patients with complaints after TKA to verify the analysis methods

Controversy remains regarding the optimal treatment for iatrogenic injury to the medial collateral ligament (MCL) during primary total knee arthroplasty (TKA). Some authors have recommended converting to a prosthesis that provides varus/valgus constraint while others have recommended primary repair. In this study we report the results of a 45 patients who sustained intra-operative MCL injuries during primary TKA that were treated with primary repair. Of 3922 consecutive primary TKA there were 48 (1.2%) intra-operative MCL lacerations or avulsions. One patient was lost and one died before 24-month follow-up. All but one patient underwent primary repair with placement of components without varus/valgus constraint. This left 45 knees with a mean follow up of 89 months (range, 24 – 214 months). The mean HSS knee scores increased from 47 to 85 points (p<0.001). No patients had subjective complaints of instability. No patients had excessive varus/valgus laxity when tested in full extension and 30 degrees of flexion. The range of motion at the time of final follow-up averaged 110 degrees (range, 85 – 130 degrees). Five knees required treatment for stiffness with 4 knees undergoing manipulation under anesthesia and 1 knee undergoing open lysis of adhesions with polyethylene articular surface exchange. Two knees underwent revision for aseptic loosening of the tibial component. In the three knees that underwent open revision, the MCL was noted to be in continuity and without laxity. Primary repair with 6 weeks of post-operative hinged bracing after iatrogenic injury to the MCL during primary TKA was successful at preventing instability although stiffness was seen in approximately 10% of patients. The increased morbidity associated with implantation of a semi-constrained or constrained implant may be unwarranted in this situation