Aims. The primary aim was to assess whether robotic total knee arthroplasty (rTKA) had a greater early knee-specific outcome when compared to manual TKA (mTKA). Secondary aims were to assess whether rTKA was associated with improved expectation fulfilment, health-related quality of life (HRQoL), and patient satisfaction when compared to mTKA. Methods. A randomized controlled trial was undertaken, and patients were randomized to either mTKA or rTKA. The primary objective was functional improvement at six months. Overall, 100 patients were randomized, 50 to each group, of whom 46 rTKA and 41 mTKA patients were available for review at six months following surgery. There were no differences between the two groups. Results. There was no difference between rTKA and mTKA groups at six months according to the Western Ontario and McMaster Universities osteoarthritis index (WOMAC) functional score (mean difference (MD) 3.8 (95% confidence interval (CI) -5.6 to 13.1); p = 0.425). There was a greater improvement in the WOMAC pain score at two months (MD 9.5 (95% CI 0.6 to 18.3); p = 0.037) in the rTKA group, although by six months no significant difference was observed (MD 6.7 (95% CI -3.6 to 17.1); p = 0.198). The rTKA group were more likely to achieve a minimal important change in their WOMAC pain score when compared to the mTKA group at two months (n = 36 (78.3%) vs n = 24 (58.5%); p = 0.047) and at six months (n = 40 (87.0%) vs n = 29 (68.3%); p = 0.036). There was no difference in satisfaction between the rTKA group (97.8%; n = 45/46) and the mTKA group (87.8%; n = 36/41) at six months (p = 0.096). There were no differences in EuroQol five-dimension questionnaire (EQ-5D) utility gain (p ≥ 0.389) or fulfilment of patient expectation (p ≥ 0.054) between the groups. Conclusion. There were no statistically significant or clinically meaningful differences in the change in WOMAC function between mTKA and rTKA at six months. rTKA was associated with a higher likelihood of achieving a clinically important change in knee pain at two and six months, but no differences in knee-specific function, patient satisfaction, health-related quality of life, or expectation fulfilment were observed. Cite this article: Bone Joint J 2023;105-B(9):961–970

Aims. The aim was to assess whether robotic-assisted total knee arthroplasty (rTKA) had greater knee-specific outcomes, improved fulfilment of expectations, health-related quality of life (HRQoL), and patient satisfaction when compared with manual TKA (mTKA). Methods. A randomized controlled trial was undertaken (May 2019 to December 2021), and patients were allocated to either mTKA or rTKA. A total of 100 patients were randomized, 50 to each group, of whom 43 rTKA and 38 mTKA patients were available for review at 12 months following surgery. There were no statistically significant preoperative differences between the groups. The minimal clinically important difference in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score was defined as 7.5 points. Results. There were no clinically or statistically significant differences between the knee-specific measures (WOMAC, Oxford Knee Score (OKS), Forgotten Joint Score (FJS)) or HRQoL measures (EuroQol five-dimension questionnaire (EQ-5D) and EuroQol visual analogue scale (EQ-VAS)) at 12 months between the groups. However, the rTKA group had significantly (p = 0.029) greater improvements in the WOMAC pain component (mean difference 9.7, 95% confidence interval (CI) 1.0 to 18.4) over the postoperative period (two, six, and 12 months), which was clinically meaningful. This was not observed for function (p = 0.248) or total (p = 0.147) WOMAC scores. The rTKA group was significantly (p = 0.039) more likely to have expectation of ‘Relief of daytime pain in the joint’ when compared with the mTKA group. There were no other significant differences in expectations met between the groups. There was no significant difference in patient satisfaction with their knee (p = 0.464), return to work (p = 0.464), activities (p = 0.293), or pain (p = 0.701). Conclusion. Patients undergoing rTKA had a clinically meaningful greater improvement in their knee pain over the first 12 months, and were more likely to have fulfilment of their expectation of daytime pain relief compared with patients undergoing mTKA. However, rTKA was not associated with a clinically significant greater knee-specific function or HRQoL, according to current definitions. Cite this article: Bone Joint J 2024;106-B(5):450–459

Aims. Histology is an established tool in diagnosing periprosthetic joint infections (PJIs). Different thresholds, using various infection definitions and histopathological criteria, have been described. This study determined the performance of different thresholds of polymorphonuclear neutrophils (≥ 5 PMN/HPF, ≥ 10 PMN/HPF, ≥ 23 PMN/10 HPF) , when using the European Bone and Joint Infection Society (EBJIS), Infectious Diseases Society of America (IDSA), and the International Consensus Meeting (ICM) 2018 criteria for PJI. Methods. A total of 119 patients undergoing revision total hip (rTHA) or knee arthroplasty (rTKA) were included. Permanent histology sections of periprosthetic tissue were evaluated under high power (400× magnification) and neutrophils were counted per HPF. The mean neutrophil count in ten HPFs was calculated (PMN/HPF). Based on receiver operating characteristic (ROC) curve analysis and the z-test, thresholds were compared. Results. Using the EBJIS criteria, a cut-off of ≥ five PMN/HPF showed a sensitivity of 93% (95% confidence interval (CI) 81 to 98) and specificity of 84% (95% CI 74 to 91). The optimal threshold when applying the IDSA and ICM criteria was ≥ ten PMN/HPF with sensitivities of 94% (95% CI 79 to 99) and 90% (95% CI 76 to 97), and specificities of 86% (95% CI 77 to 92) and 92% (95% CI 84 to 97), respectively. In rTKA, a better performance of histopathological analysis was observed in comparison with rTHA when using the IDSA criteria (p < 0.001). Conclusion. With high accuracy, histopathological analysis can be supported as a confirmatory criterion in diagnosing periprosthetic joint infections. A threshold of ≥ five PMN/HPF can be recommended to distinguish between septic and aseptic loosening, with an increased possibility of detecting more infections caused by low-virulence organisms. However, neutrophil counts between one and five should be considered suggestive of infection and interpreted carefully in conjunction with other diagnostic test methods. Cite this article: Bone Joint Res 2021;10(8):536–547

Aims. Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised. Methods. This retrospective, observational study reviewed patients who underwent unilateral, aseptic rTKA at an academic orthopaedic speciality hospital between June 2011 and April 2020 with > one-year of follow-up. Patients were dichotomized based on whether this was their first revision procedure or not. Patient demographics, surgical factors, postoperative outcomes, and re-revision rates were compared between the groups. Results. A total of 663 cases were identified (486 index rTKAs and 177 multiply revised TKAs). There were no differences in demographics, rTKA type, or indication for revision. Multiply revised patients had significantly longer rTKA operative times (p < 0.001), and were more likely to be discharged to an acute rehabilitation centre (6.2% vs 4.5%) or skilled nursing facility (29.9% vs 17.5%; p = 0.003). Patients who had been multiply revised were also significantly more likely to have subsequent reoperation (18.1% vs 9.5%; p = 0.004) and re-revision (27.1% vs 18.1%; p = 0.013). The number of previous revisions did not correlate with the number of subsequent reoperations (r = 0.038; p = 0.670) or re-revisions (r = −0.102; p = 0.251). Conclusion. Multiply revised TKA had worse outcomes, with higher rates of facility discharge, longer operative times, and greater reoperation and re-revision rates compared to index rTKA. Cite this article: Bone Jt Open 2023;4(5):393–398

Aims. Revision total knee arthroplasty (rTKA) and revision total hip arthroplasty (rTHA) are complex procedures with higher rates of re-revision, complications, and mortality compared to primary TKA and THA. We report the effects of the establishment of a revision arthroplasty network (the East Midlands Specialist Orthopaedic Network; EMSON) on outcomes of rTKA and rTHA. Methods. The revision arthroplasty network was established in January 2015 and covered five hospitals in the Nottinghamshire and Lincolnshire areas of the East Midlands of England. This comprises a collaborative weekly multidisciplinary meeting where upcoming rTKA and rTHA procedures are discussed, and a plan agreed. Using the Hospital Episode Statistics database, revision procedures carried out between April 2011 and March 2018 (allowing two-year follow-up) from the five network hospitals were compared to all other hospitals in England. Age, sex, and mean Hospital Frailty Risk scores were used as covariates. The primary outcome was re-revision surgery within one year of the index revision. Secondary outcomes were re-revision surgery within two years, any complication within one and two years, and median length of hospital stay. Results. A total of 57,621 rTHA and 33,828 rTKA procedures were performed across England, of which 1,485 (2.6%) and 1,028 (3.0%), respectively, were conducted within the network. Re-revision rates within one year for rTHA were 7.3% and 6.0%, and for rTKA were 11.6% and 7.4% pre- and postintervention, respectively, within the network. This compares to a pre-to-post change from 7.4% to 6.8% for rTHA and from 11.7% to 9.7% for rTKA for the rest of England. In comparative interrupted time-series analysis for rTKA there was a significant immediate improvement in one-year re-revision rates for the revision network compared to the rest of England (p = 0.024), but no significant change for rTHA (p = 0.504). For the secondary outcomes studied, there was a significant improvement in trend for one- and two-year complication rates for rTHA for the revision network compared to the rest of England. Conclusion. Re-revision rates for rTKA and complication rates for rTHA improved significantly at one and two years with the introduction of a revision arthroplasty network, when compared to the rest of England. Most of the outcomes studied improved to a greater extent in the network hospitals compared to the rest of England when comparing the pre- and postintervention periods. Cite this article: Bone Joint J 2023;105-B(6):641–648

Aims. To identify variables independently associated with same-day discharge (SDD) of patients following revision total knee arthroplasty (rTKA) and to develop machine learning algorithms to predict suitable candidates for outpatient rTKA. Methods. Data were obtained from the American College of Surgeons National Quality Improvement Programme (ACS-NSQIP) database from the years 2018 to 2020. Patients with elective, unilateral rTKA procedures and a total hospital length of stay between zero and four days were included. Demographic, preoperative, and intraoperative variables were analyzed. A multivariable logistic regression (MLR) model and various machine learning techniques were compared using area under the curve (AUC), calibration, and decision curve analysis. Important and significant variables were identified from the models. Results. Of the 5,600 patients included in this study, 342 (6.1%) underwent SDD. The random forest (RF) model performed the best overall, with an internally validated AUC of 0.810. The ten crucial factors favoring SDD in the RF model include operating time, anaesthesia type, age, BMI, American Society of Anesthesiologists grade, race, history of diabetes, rTKA type, sex, and smoking status. Eight of these variables were also found to be significant in the MLR model. Conclusion. The RF model displayed excellent accuracy and identified clinically important variables for determining candidates for SDD following rTKA. Machine learning techniques such as RF will allow clinicians to accurately risk-stratify their patients preoperatively, in order to optimize resources and improve patient outcomes. Cite this article: Bone Jt Open 2023;4(6):399–407

Aims. The aim of this study was to measure the effect of hospital case volume on the survival of revision total knee arthroplasty (RTKA). Methods. This is a retrospective analysis of Scottish Arthroplasty Project data, a nationwide audit which prospectively collects data on all arthroplasty procedures performed in Scotland. The primary outcome was RTKA survival at ten years. The primary explanatory variable was the effect of hospital case volume per year on RTKA survival. Kaplan-Meier survival curves were plotted with 95% confidence intervals (CIs) to determine the lifespan of RTKA. Multivariate Cox proportional hazards were used to estimate relative revision risks over time. Hazard ratios (HRs) were reported with 95% CI, and p-value < 0.05 was considered statistically significant. Results. From 1998 to 2019, 8,301 patients (8,894 knees) underwent RTKA surgery in Scotland (median age at RTKA 70 years (interquartile range (IQR) 63 to 76); median follow-up 6.2 years (IQR 3.0 to 10.2). In all, 4,764 (53.6%) were female, and 781 (8.8%) were treated for infection. Of these 8,894 knees, 957 (10.8%) underwent a second revision procedure. Male sex, younger age at index revision, and positive infection status were associated with need for re-revision. The ten-year survival estimate for RTKA was 87.3% (95% CI 86.5 to 88.1). Adjusting for sex, age, surgeon volume, and indication for revision, high hospital case volume was significantly associated with lower risk of re-revision (HR 0.78 (95% CI 0.64 to 0.94, p < 0.001)). The risk of re-revision steadily declined in centres performing > 20 cases per year; risk reduction was 16% with > 20 cases; 22% with > 30 cases; and 28% with > 40 cases. The lowest level of risk was associated with the highest volume centres. Conclusion. The majority of RTKA in Scotland survive up to ten years. Increasing yearly hospital case volume above 20 cases is independently associated with a significant risk reduction of re-revision. Development of high-volume tertiary centres may lead to an improvement in the overall survival of RTKA. Cite this article: Bone Joint J 2021;103-B(4):602–609

Aims. It has previously been shown that higher-volume hospitals have better outcomes following revision total knee arthroplasty (rTKA). We were unable to identify any studies which investigated the effect of surgeon volume on the outcome of rTKA. We sought to investigate whether patients of high-volume (HV) rTKA surgeons have better outcomes following this procedure compared with those of low-volume (LV) surgeons. Methods. This retrospective study involved patients who underwent aseptic unilateral rTKA between January 2016 and March 2019, using the database of a large urban academic medical centre. Surgeons who performed ≥ 19 aseptic rTKAs per year during the study period were considered HV and those who performed < 19 per year were considered LV. Demographic characteristics, surgical factors, and postoperative outcomes were compared between the two groups. Results. A total of 308 rTKAs were identified, 132 performed by HV surgeons and 176 by 22 LV surgeons. The LV group had a significantly greater proportion of non-smokers (59.8% vs 49.2%; p = 0.029). For all types of revision, HV surgeons had significantly shorter mean operating times by 17.75 minutes (p = 0.007). For the 169 full revisions (85 HV, 84 LV), HV surgeons had significantly shorter operating times (131.12 (SD 33.78) vs 171.65 (SD 49.88) minutes; p < 0.001), significantly lower re-revision rates (7.1% vs 19.0%; p = 0.023) and significantly fewer re-revisions (0.07 (SD 0.26) vs 0.29 (SD 0.74); p = 0.017). Conclusion. Patients of HV rTKA surgeons have better outcomes following full rTKA. These findings support the development of revision teams within arthroplasty centres of excellence to offer patients the best possible outcomes following rTKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):131–136

Aims. To map literature on prognostic factors related to outcomes of revision total knee arthroplasty (rTKA), to identify extensively studied factors and to guide future research into what domains need further exploration. Methods. We performed a systematic literature search in MEDLINE, Embase, and Web of Science. The search string included multiple synonyms of the following keywords: "revision TKA", "outcome" and "prognostic factor". We searched for studies assessing the association between at least one prognostic factor and at least one outcome measure after rTKA surgery. Data on sample size, study design, prognostic factors, outcomes, and the direction of the association was extracted and included in an evidence map. Results. After screening of 5,660 articles, we included 166 studies reporting prognostic factors for outcomes after rTKA, with a median sample size of 319 patients (30 to 303,867). Overall, 50% of the studies reported prospectively collected data, and 61% of the studies were performed in a single centre. In some studies, multiple associations were reported; 180 different prognostic factors were reported in these studies. The three most frequently studied prognostic factors were reason for revision (213 times), sex (125 times), and BMI (117 times). Studies focusing on functional scores and patient-reported outcome measures as prognostic factor for the outcome after surgery were limited (n = 42). The studies reported 154 different outcomes. The most commonly reported outcomes after rTKA were: re-revision (155 times), readmission (88 times), and reinfection (85 times). Only five studies included costs as outcome. Conclusion. Outcomes and prognostic factors that are routinely registered as part of clinical practice (e.g. BMI, sex, complications) or in (inter)national registries are studied frequently. Studies on prognostic factors, such as functional and sociodemographic status, and outcomes as healthcare costs, cognitive and mental function, and psychosocial impact are scarce, while they have been shown to be important for patients with osteoarthritis. Cite this article: Bone Jt Open 2023;4(5):338–356

Aims. Tibial tubercle osteotomy (TTO) facilitates surgical exposure and protects the extensor mechanism during revision total knee arthroplasty (rTKA). The purpose of this study was to determine the rates of bony union, complications, and reoperations following TTO during rTKA, to assess the functional outcomes of rTKA with TTO at two years’ minimum follow-up, and to identify the risk factors of failure. Methods. Between January 2010 and September 2020, 695 rTKAs were performed and data were entered into a prospective database. Inclusion criteria were rTKAs with concomitant TTO, without extensor mechanism allograft, and a minimum of two years’ follow-up. A total of 135 rTKAs were included, with a mean age of 65 years (SD 9.0) and a mean BMI of 29.8 kg/m. 2. (SD 5.7). The most frequent indications for revision were infection (50%; 68/135), aseptic loosening (25%; 34/135), and stiffness (13%; 18/135). Patients had standardized follow-up at six weeks, three months, six months, and annually thereafter. Complications and revisions were evaluated at the last follow-up. Functional outcomes were assessed using the Knee Society Score (KSS) and range of motion. Results. The mean follow-up was 51 months (SD 26; 24 to 121). Bony union was confirmed in 95% of patients (128/135) at a mean of 3.4 months (SD 2.7). The complication rate was 15% (20/135), consisting of nine tibial tubercle fracture displacements (6.7%), seven nonunions (5%), two delayed unions, one tibial fracture, and one wound dehiscence. Seven patients (5%) required eight revision procedures (6%): three bone grafts, three osteosyntheses, one extensor mechanism allograft, and one wound revision. The functional scores and flexion were significantly improved after surgery: mean KSS knee, 48.8 (SD 17) vs 79.6 (SD 20; p < 0.001); mean KSS function, 37.6 (SD 21) vs 70.2 (SD 30; p < 0.001); mean flexion, 81.5° (SD 33°) vs 93° (SD 29°; p = 0.004). Overall, 98% of patients (n = 132) had no extension deficit. The use of hinge implants was a significant risk factor for tibial tubercle fracture (p = 0.011). Conclusion. TTO during rTKA was an efficient procedure to improve knee exposure with a high union rate, but had significant specific complications. Functional outcomes were improved at mid term. Cite this article: Bone Joint J 2023;105-B(10):1078–1085

Aims. Revision total knee arthroplasty (rTKA) accounts for approximately 5% to 10% of all TKAs. Although the complexity of these procedures is well recognized, few investigators have evaluated the cost and value-added with the implementation of a dedicated revision arthroplasty service. The aim of the present study is to compare and contrast surgeon productivity in several differing models of activity. Materials and Methods. All patients that underwent primary or revision TKA from January 2016 to June 2018 were included as the primary source of data. All rTKA patients were categorized by the number of components revised (e.g. liner exchange, two or more components). Three models were used to assess the potential surgical productivity of a dedicated rTKA service : 1) work relative value unit (RVU) versus mean surgical time; 2) primary TKA with a single operating theatre (OT) versus rTKA with a single OT; and 3) primary TKA with two OTs versus rTKA with a single OT. Results. In total, 4570 procedures were performed: 4128 primary TKAs, 51 TKA liner exchanges, and 391 full rTKAs. Surgical time was significantly different between the primary TKA, liner exchange, and rTKA cohorts (100.6, 97.1, and 141.7 minutes, respectively; p < 0.001). Primary TKA yielded a mean of 7.1% more RVU/min per procedure than rTKA. Our one-OT model demonstrated that primary TKA (n = 4) had a 1.9% RVU/day advantage over rTKA (n = 3). If two OTs are used for primary TKA (n = 6), the outcome strongly favours primary TKA by an added 34.6% RVUs/day. Conclusion. Our results suggest that a dedicated rTKA service would lead to lower surgeon remuneration based on the current RVU paradigm. Revision arthroplasty specialists may need additional or alternative incentives to promote the development of a dedicated revision service. Through such an approach, healthcare organizations could enhance the quality of care provided, but surgeon productivity measures would need to be adjusted to reflect the burden of these cases. Cite this article: Bone Joint J 2019;101-B:675–681

Aims. Enhanced perioperative protocols have significantly improved patient recovery following primary total knee arthroplasty (TKA). Little has been investigated the effectiveness of these protocols for revision TKA (RTKA). We report on a matched group of aseptic revision and primary TKA patients treated with an identical pain and rehabilitation programmes. Methods. Overall, 40 aseptic full-component RTKA patients were matched (surgical date, age, sex, and body mass index (BMI)) to a group of primary cemented TKA patients. All RTKAs had new uncemented stemmed femoral and tibial components with metaphyseal sleeves. Both groups were treated with an identical postoperative pain protocol. Patients were followed for at least two years. Knee Society Scores (KSS) at six weeks and at final follow-up were recorded for both groups. Results. There was no difference in mean length of stay between the primary TKA (1.2 days (0.83 to 2.08)) and RTKA patients (1.4 days (0.91 to 2.08). Mean oral morphine milligram (mg) equivalent dosing (MED) during the hospitalization was 42 mg/day for the primary TKA and 38 mg/day for the RTKA groups. There were two readmissions: gastrointestinal disturbance (RTKA) and urinary retention (primary TKA). There no were reoperations, wound problems, thromboembolic events or manipulations in either group. Mean overall KSS for the RTKA group was 87.3 (45 to 99) at six-week follow-up and 89.1 (52 to 100) at final follow-up (mean 3.9 years, (3.9 to 9.0)). Mean overall KSS for the primary group was 89.9 (71 to 100) at six-week follow-up and 93.42 (73 to 100) at final follow-up (mean 3.5 years (2.5 to 9.2)). Conclusion. An identical pain and rehabilitation protocol used for primary TKA patients can enable certain full-component aseptic RTKA patients to have a similar early functional outcome. Cite this article: Bone Joint J 2020;102-B(6 Supple A):96–100

Aims. Obtaining solid implant fixation is crucial in revision total knee arthroplasty (rTKA) to avoid aseptic loosening, a major reason for re-revision. This study aims to validate a novel grading system that quantifies implant fixation across three anatomical zones (epiphysis, metaphysis, diaphysis). Methods. Based on pre-, intra-, and postoperative assessments, the novel grading system allocates a quantitative score (0, 0.5, or 1 point) for the quality of fixation achieved in each anatomical zone. The criteria used by the algorithm to assign the score include the bone quality, the size of the bone defect, and the type of fixation used. A consecutive cohort of 245 patients undergoing rTKA from 2012 to 2018 were evaluated using the current novel scoring system and followed prospectively. In addition, 100 first-time revision cases were assessed radiologically from the original cohort and graded by three observers to evaluate the intra- and inter-rater reliability of the novel radiological grading system. Results. At a mean follow-up of 90 months (64 to 130), only two out of 245 cases failed due to aseptic loosening. Intraoperative grading yielded mean scores of 1.87 (95% confidence interval (CI) 1.82 to 1.92) for the femur and 1.96 (95% CI 1.92 to 2.0) for the tibia. Only 3.7% of femoral and 1.7% of tibial reconstructions fell below the 1.5-point threshold, which included the two cases of aseptic loosening. Interobserver reliability for postoperative radiological grading was 0.97 for the femur and 0.85 for the tibia. Conclusion. A minimum score of 1.5 points for each skeletal segment appears to be a reasonable cut-off to define sufficient fixation in rTKA. There were no revisions for aseptic loosening at mid-term follow-up when this fixation threshold was achieved or exceeded. When assessing first-time revisions, this novel grading system has shown excellent intra- and interobserver reliability. Cite this article: Bone Joint J 2024;106-B(5):468–474

Aims. The aim of this study was to assess the incidence the microbiological spectrum and clinical outcome of hip and knee revision arthroplasties with unexpected-positive-intraoperative-cultures (UPIC) at a single center with minimum follow up of 2 years. Methods. We retrospectively analyzed our prospectively maintained institutional arthroplasty registry. Between 2011 and 2020 we performed presumably aseptic rTHA (n=939) and rTKA (n= 1,058). Clinical outcome, re-revision rates and causes as well as the microbiological spectrum were evaluated. Results. In total, 219/939 (23.3%) rTHA and 114/ 1,058 (10.8%) rTKA had a UPIC (p<0.001). Single positive intraoperative cultures were found in 173/219 (78.9%) in rTHA and 99/114 (86.8%) in rTKA, whereas 46/219 (21.0%) rTHA and 15/114 (13.2%) rTKA had positive results in ≥2 intraoperative cultures. A total of 390 microorganisms were found among the 333 cases. Staphylococcus epidermidis 30.9%, CoNS (21.9%), Cutibacterium acnes 21.1%, and Bacillus spp. 7.3% were the most common microorganisms. Overall, detected microorganisms showed high sensitivity to daptomycin (96.6%), vancomycin (97.3%) and linezolid (98.0%). After a minimum follow up of 2 years (rTHA 1,470 (735; 3,738) days; rTKA 1,474 (749; 4,055) days). During the 2-year follow-up, 8 patients died and 5 were lost to follow-up. There were 54/219 (24.7%) re-revision in rTHa and 20/114 (17.5%) in rTKA. Overall, there were 23 (10.5%) septic re-rTHA and 9 (7.9%) septic re-rTKA as well as 31 (14.2%) aseptic re-rTHA and 11 (9.6%) aseptic re-rTKA. Patients with previous septic revisions bevor UPIC procedure showed a significant higher risk for septic re-revision (p<0.05). Moreover, there were less septic re-revisions after single culture positive UPIC (rTHA: 16/173 (9.2%); rTKA 6/99 (6.1%)) compared to ≥2 positive intraoperative cultures UPIC (rTHA: 7/46 (15.2%); rTKA 3/15 (20.0%)). The most common reason for re-revision in the rTHA-group was aseptic loosening of the cup (34.2%) or of the stem (23.3%), dislocation (18.3%) and periprosthetic-fractures (7.8%). In the rTKA-group it was aseptic loosening (40.4%), instability (24.6%) and secondary patella resurfacing (7.9%). There was a higher septic re-revision rate in consecutive revisions than in planned revisions 17.3% vs. 8.5% in the rTHA-group and 14.3% vs. 7.5% in the rTKA-group, p<0.001. Conclusion. UPICs are common in rTJA. The rate was higher in hips which may partly explained by the easier pre op joint aspiration in the knee. UPIC may lead to an increase in subsequent re-revisions

Aims. Both the femoral and tibial component are usually cemented at revision total knee arthroplasty (rTKA), while stems can be added with either cemented or press-fit (hybrid) fixation. The aim of this study was to compare the long-term stability of rTKA with cemented and press-fitted stems, using radiostereometric analysis (RSA). Methods. This is a follow-up of a randomized controlled trial, initially involving 32 patients, of whom 19 (nine cemented, ten hybrid) were available for follow-up ten years postoperatively, when further RSA measurements were made. Micromotion of the femoral and tibial components was assessed using model-based RSA software (RSAcore). The clinical outcome was evaluated using the Knee Society Score (KSS), the Knee injury and Osteoarthritis Outcome Score (KOOS), and visual analogue scale (pain and satisfaction). Results. The median total femoral translation and rotation at ten years were 0.39 mm (interquartile range (IQR) 0.20 to 0.54) and 0.59° (IQR 0.46° to 0.73°) for the cemented group and 0.70 mm (IQR 0.15 to 0.77) and 0.78° (IQR 0.47° to 1.43°) for the hybrid group. For the tibial components this was 0.38 mm (IQR 0.33 to 0.85) and 0.98° (IQR 0.38° to 1.34°) for the cemented group and 0.42 mm (IQR 0.30 to 0.52) and 0.72° (IQR 0.62° to 0.82°) for the hybrid group. None of these values were significantly different between the two groups and there were no significant differences between the clinical scores in the two groups at this time. There was only one re-revision, in the hybrid group, for infection and not for aseptic loosening. Conclusion. These results show good long-term fixation with no difference in micromotion and clinical outcome between fully cemented and hybrid fixation in rTKA, which builds on earlier short- to mid-term results. The patients all had type I or II osseous defects, which may in part explain the good results. Cite this article: Bone Joint J 2022;104-B(7):875–883

Background. Obesity has been linked with increased rates of knee osteoarthritis. Limited information is available on the survival and functional outcome results of rTKR in the obese patients. This registry-based study aimed to identify whether BMI is an independent risk factor for poorer functional outcomes and /or implant survival in rTKA. Methods. New Zealand Joint Registry (NZJR) data of patients who underwent rTKA from 1st January 2010 to January 2023 was performed. Demographics, American Society of Anesthesiologists (ASA), BMI, Operative time, indications for revision and components revised of the patients undergoing rTKA was collected. Oxford knee score (OKS) at 6 months and rates of second revision (re- revision) were stratified based on standardised BMI categories. Results. Of the 2687 revisions, functional outcome scores were available for 1261 patients. Oxford knee scores following rTKA are significantly inferior in higher BMI patients (36.5 vs 31.5 p<0.001). This held true when adjusted for age (35.7 vs 30.9 p<0.001). Tibial component loosening was a more common indication for revision in patients with BMI >40 (31.1% vs 21% for BMI <25), whereas periprosthetic femoral fracture was significantly more commonly seen in patients with BMI <25. Re-revision rates displayed no significant differences between any pairs of BMI groups (2.18/100 component years) and adjusting for age and sex did not alter this (p= 0.462). Indications for re-revision were also not different between BMI categories. Over 50% of the rTKA patients were obese. Significantly more obese patients were ASA grade 3,4 and more were <75 years. Operative time was longer in the obese patients (p<0.001). Conclusions. Although overall re-revision rates are similar between all BMI categories, the functional outcomes favour those with lower BMI. Patients with higher BMI are younger, more comorbid and carry potentially higher perioperative risks. The registry data provides valuable information when providing counsel to patients undergoing rTKA and lends further support to optimising patients prior to pTKA

Aims. Metaphyseal tritanium cones can be used to manage the tibial bone loss commonly encountered at revision total knee arthroplasty (rTKA). Tibial stems provide additional fixation and are generally used in combination with cones. The aim of this study was to examine the role of the stems in the overall stability of tibial implants when metaphyseal cones are used for rTKA. Methods. This computational study investigates whether stems are required to augment metaphyseal cones at rTKA. Three cemented stem scenarios (no stem, 50 mm stem, and 100 mm stem) were investigated with 10 mm-deep uncontained posterior and medial tibial defects using four loading scenarios designed to mimic activities of daily living. Results. Small micromotions (mean < 12 µm) were found to occur at the bone-implant interface for all loading cases with or without a stem. Stem inclusion was associated with lower micromotion, however these reductions were too small to have any clinical significance. Peak interface micromotion, even when the cone is used without a stem, was too small to effect osseointegration. The maximum difference occurred with stair descent loading. Stress concentrations in the bone occurred around the inferior aspect of each implant, with the largest occurring at the end of the long stem; these may lead to end-of-stem pain. Stem use is also found to result in stress shielding in the bone along the stem. Conclusion. When a metaphyseal cone is used at rTKA to manage uncontained posterior or medial defects of up to 10 mm depth, stem use may not be necessary. Cite this article:Bone Joint Res. 2020;9(4):162–172

Little information exists regarding optimal tibial stem usage in revision total knee arthroplasty (rTKA) utilising a tibial trabecular metal (TM) cone. The purpose of this study was to compare 1) functional outcomes, 2) radiographic outcomes, and 3) implant survivorship in rTKA utilising TM cones combined with either short stems (SS) or long stems (LS) at minimum two-years clinical follow-up. In this retrospective, multi-centre study, patients undergoing TM cone utilising rTKA between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post-operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol-5D (EQ-5D-5L) data were collected at most recent follow-up. In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow-up was 4.0 years. Failure free survival was 94.5% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow-up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, p = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (p = 0.73) in the SS and LS groups, respectively. Tibial SS combined with TM cones performed as well as LS in rTKA at minimum two-years follow-up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA

Abstract. Introduction. Revision total knee arthroplasty (RTKA) is a complex procedure with higher rates of re-revision, complications and mortality compared to primary TKA. We report the effects of the establishment of a Revision Arthroplasty Network (The East Midlands Specialist Orthopaedic Network; EMSON). Methodology. The Revision Arthroplasty Network was established in January 2015 and covered the Nottinghamshire and Lincolnshire areas of England. This comprises a collaborative weekly multidisciplinary meeting where upcoming RTKA procedures are discussed, and a plan agreed. Using the Hospital Episode Statistics database, RTKA procedures carried out between 2011 and 2018 from the five EMSON hospitals were compared to all other hospitals in England. Age, sex, and Hospital Frailty Risk scores were used as covariates. The primary outcome was re-revision surgery within 1 year of the index revision. Secondary outcomes were re-revision surgery within two years, any complication within one and two years and median length of stay. Results. 33,828 RTKA procedures were performed across England; 1,028 (3.0%) were conducted within EMSON. Re-revision rates within 1 year were 11.6% and 7.4% pre- and post-intervention respectively within the network. This compares to a pre-post change from 11.7% to 9.7% for the rest of England. In comparative interrupted time-series analysis, there was a significant immediate improvement in re-revision rates for EMSON hospitals compared to the rest of England at 1 year (p = 0.024) and 2 years (p=0.032). Conclusion. Re-revision rates for RTKA improved significantly at one and two years with the introduction of EMSON, when compared to the rest of England

Aims. Single-stage revision total knee arthroplasty (rTKA) is gaining popularity in treating chronic periprosthetic joint infections (PJIs). We have introduced this approach to our clinical practice and sought to evaluate rates of reinfection and re-revision, along with predictors of failure of both single- and two-stage rTKA for chronic PJI. Methods. A retrospective comparative cohort study of all rTKAs for chronic PJI between 1 April 2003 and 31 December 2018 was undertaken using prospective databases. Patients with acute infections were excluded; rTKAs were classified as single-stage, stage 1, or stage 2 of two-stage revision. The primary outcome measure was failure to eradicate or recurrent infection. Variables evaluated for failure by regression analysis included age, BMI, American Society of Anesthesiologists grade, infecting organisms, and the presence of a sinus. Patient survivorship was also compared between the groups. Results. A total of 292 consecutive first-time rTKAs for chronic PJI were included: 82 single-stage (28.1%); and 210 two-stage (71.9%) revisions. The mean age was 71 years (27 to 90), with 165 females (57.4%), and a mean BMI of 30.9 kg/m. 2. (20 to 53). Significantly more patients with a known infecting organism were in the single-stage group (93.9% vs 80.47%; p = 0.004). The infecting organism was identified preoperatively in 246 cases (84.2%). At a mean follow-up of 6.3 years (2.0 to 17.6), the failure rate was 6.1% in the single-stage, and 12% in the two-stage groups. All failures occurred within four years of treatment. The presence of a sinus was an independent risk factor for failure (odds ratio (OR) 4.97; 95% confidence interval (CI) 1.593 to 15.505; p = 0.006), as well as age > 80 years (OR 5.962; 95% CI 1.156 to 30.73; p = 0.033). The ten-year patient survivorship rate was 72% in the single-stage group compared with 70.5% in the two-stage group. This difference was not significant (p = 0.517). Conclusion. Single-stage rTKA is an effective strategy with a high success rate comparable to two-stage approach in appropriately selected patients. Cite this article: Bone Joint J 2021;103-B(8):1373–1379

Aims. The aim of this study was to perform a systematic review and bias evaluation of the current literature to create an overview of risk factors for re-revision following revision total knee arthroplasty (rTKA). Methods. A systematic search of MEDLINE and Embase was completed in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The studies were required to include a population of index rTKAs. Primary or secondary outcomes had to be re-revision. The association between preoperative factors and the effect on the risk for re-revision was also required to be reported by the studies. Results. The search yielded 4,847 studies, of which 15 were included. A majority of the studies were retrospective cohorts or registry studies. In total, 26 significant risk factors for re-revision were identified. Of these, the following risk factors were consistent across multiple studies: age at the time of index revision, male sex, index revision being partial revision, and index revision due to infection. Modifiable risk factors were opioid use, BMI > 40 kg/m. 2. , and anaemia. History of one-stage revision due to infection was associated with the highest risk of re-revision. Conclusion. Overall, 26 risk factors have been associated with an increased risk of re-revision following rTKA. However, various levels of methodological bias were found in the studies. Future studies should ensure valid comparisons by including patients with identical indications and using clear definitions for accurate assessments. Cite this article: Bone Jt Open 2024;5(8):644–651

Abstract. Introduction. Revision total knee arthroplasty (rTKA) in elderly patients (>85 years) is associated with increased mortality, hospital stay and a high rate (55%) of complications. The objective was to assess PROMs in elderly patients undergoing rTKA. Methods. A retrospective cohort study of consecutive patients undergoing rTKA at an arthroplasty centre from 2001–2022 were compared to a control group (aged 50–79y) matched for gender, diagnosis & surgery year. The commonest reasons for revision in elderly patients was aseptic loosening (53/100), infection (21/100) and fracture (7/100). One-year patient-reported outcome data was available for 64%. Results. 100 patients underwent rTKA with a mean age of 84 years (range 80–97 years, SD 3) compared to a matched control group of younger patients (mean age 69y). Preoperative function was poor, with a mean Oxford knee score (OKS) of 40/100 in elderly and 43/100 in younger patients (p=0.164). At one-year postop, mean OKS was comparable between elderly and young patients (81 and 84/100 respectively, p=0.289). The number of patients with severe pain at one year was also comparable (4% elderly and 7% young respectively, p=0.177). The improvement in OKS for elderly patients was sustained at three (82 95% CI 58–100, 14/100 known) and five years. Overall complication rate was 54%. 14% were dead at 1 year and 56% were dead at five-years. Conclusion. Elderly patients undergoing elective revision TKA show a mean improvement in Oxford knee score of +38 at one year. This is the same as younger patients and is sustained at three and five years

Abstract. Introduction. Little is known about employment following revision total knee arthroplasty (RTKA). This study aims to describe factors associated with returning to employment in patients of working age who underwent RTKA surgery. Methodology. We performed a retrospective assessment of all patients aged ≤65 who underwent RTKA at our NHS institution between 2006 and 2020. All indications and revision procedures were included. Pre-operative demographics, indication for surgery and Oxford Knee Scores (OKS) were recorded. Postal questionnaires were sent to patients including patient reported outcome measures and departmental questionnaire asking patients about employment status pre- and post-operatively. Results. 132 procedures were performed in 113 patients. Median follow up was 5.5 years (2.4–9.0). Mean age was 58 (5.8) and 50% (57) were male. 62 patients undergoing 74 procedures responded to postal questionnaires and were included in the study. 53% (33) were employed prior to surgery and 61% (38) returned to work at a median of 12 weeks (3–150). Of the 24 who did not return to work, 7 reported intending to return to work. Those patients who returned to work had increased pre-operative OKS (16.9 vs 13.6) and mean improvement (16.5 vs 12.4). Conclusion. This study is limited by small numbers and its observational nature. In this population the majority of patients who wished to return to work after RTKA were able to do so. This provides some reassurance when counselling patients. Prospective studies to better understand the factors that predict return to work will be important with increasing demands from surgery

The aim of this study was to measure the effect of hospital case-volume on the survival of revision total knee arthroplasty (RTKA). A retrospective analysis of Scottish Arthroplasty Project data was performed. The primary outcome was RTKA survival at ten years. The primary explanatory variable was annual hospital case-volume. Kaplan-Meier survival curves were plotted with 95% confidence intervals (CI) to determine the lifespan of RTKA. Multivariable Cox proportional hazards were used to estimate relative revision risks over time. From 1998 to 2019, 8894 patients underwent RTKA surgery in Scotland (median age 70 years, median follow-up 6.2 years, 4789 (53.5%) females; 718 (8.8%) for infection). Of these patients, 957 (10.8%) underwent a second revision procedure on their knee. Male sex, younger age at index revision, and positive infection status were associated with need for re-revision. The ten-year survival estimate for RTKA was 87.3% (95%CI 86.5–88.1). Adjusting for gender, age, surgeon volume and infection status, increasing hospital case-volume was significantly associated with lower risk of re-revision (Hazard Ratio 0.78 (0.64–0.94, p<0.001)). The risk of re-revision steadily declined in centres performing >20 cases per year: relative risk reduction 16% with >20 cases; 22% with >30 cases; and 28% with >40 cases. The majority of RTKA in Scotland survive up to ten years. Increasing yearly hospital case-volume above 20 cases is independently associated with a significant risk reduction of re-revision. Development of high-volume tertiary centres may lead to an improvement in the overall survival of RTKA

Aims. The aim of this study was to establish the results of isolated exchange of the tibial polyethylene insert in revision total knee arthroplasty (RTKA) in patients with well-fixed femoral or tibial components. We report on a series of RTKAs where only the polyethylene was replaced, and the patients were followed for a mean of 13.2 years (10.0 to 19.1). Patients and Methods. Our study group consisted of 64 non-infected, grossly stable TKA patients revised over an eight-year period (1998 to 2006). The mean age of the patients at time of revision was 72.2 years (48 to 88). There were 36 females (56%) and 28 males (44%) in the cohort. All patients had received the same cemented, cruciate-retaining patella resurfaced primary TKA. All subsequently underwent an isolated polyethylene insert exchange. The mean time from the primary TKA to RTKA was 9.1 years (2.2 to 16.1). Results. At final follow-up, 13 patients had died, leaving 51 patients for study. Only seven of these patients had required re-operation. Knee Society scores (KSS) prior to RTKA were a mean of 78.4 (24 to 100). By six weeks post-revision, the mean total KSS was 93.5 (38 to 100) and at final follow-up, they had a mean of 91.6 (36 to 100). Conclusion. In appropriate circumstances, where the femoral and tibial components are satisfactorily aligned and well fixed, and where the soft tissues can be balanced, a polyethylene exchange alone can provide a durable solution for these RTKA patients. Cite this article: Bone Joint J 2019;101-B(7 Supple C):104–107

Aims. The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes. Methods. A retrospective consecutive study of all patients who underwent a rTKA using the fully cemented SMILES rotating hinge prosthesis between 2005 to 2018. Outcome measures included aseptic loosening, reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both prospectively collected local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Results. Overall, 69 consecutive patients (69 knees) were included with a median age of 78 years (interquartile range 69 to 84), and there were 46 females (66.7%). Indications were septic revisions in 26 (37.7%), and aseptic aetiology in the remining 43 (62.3%). The mean follow-up was 9.7 years (4 to 18), and the overall complication was rate was 7.24%, all with patellofemoral complications. Failure rate with ‘any cause revision’ was 5.8%. There was one case of aseptic loosening of the femoral component. At ten years, 17/69 patients (24.63%) had died, and implant survivorship was 92.2%. Conclusion. In our experience, the SMILES rotating hinge prosthesis achieves satisfactory long-term outcomes with ten-year implant survivorship of 92.2% and a patellofemoral complication rate of 7.24%. Cite this article: Bone Jt Open 2023;4(10):776–781

Introduction. Previous studies have demonstrated that higher volume hospitals have better outcomes following revision total knee arthroplasty (rTKA), in current literature there are no reports investigating the effect of surgeon volume. The purpose of this study is to investigate if patients of high-volume revision surgeons have better outcomes following rTKA as compared to patients of low volume surgeons. Methods. This retrospective observational analysis examined the rTKA database at a large urban academic medical center for aseptic, unilateral rTKA between January 2016 and March 2019 with at least 1-year of follow-up. Surgeon operative volume during the same time period was evaluated. Surgeons who performed at least 18 aseptic rTKA per year were considered high volume (HV), whereas surgeons who performed fewer than 18 aseptic rTKA per year were considered low volume (LV). Demographics, surgical factors, and post-operative outcomes were collected and compared between the two cohorts. A post-hoc power analysis was conducted for full revisions (1-ß=0.909, α=0.05). Results. 307 cases were identified: 177 performed by LV surgeons and 130 performed by HV surgeons. The only demographic difference was a greater proportion of non-smokers in the LV cohort (59.4% vs. 50.0%; p=0.031). Patients of HV surgeons were more likely to receive a full revision (64.6% vs. 47.5%; p<0.001). For all revisions, HV surgeons had shorter surgical times by about 17 minutes (p=0.010). For the 168 full revisions (84 HV, 84 LV), patients of HV surgeons had shorter hospital stays (2.92±1.62 vs. 3.57±2.69 days; p=0.048), shorter surgical times (131.42±33.86 vs. 171.65±49.88 minutes; p<0.001), lower re-revision rates (7.1% vs. 19.0%; p=0.038), and fewer re-revisions (0.07±0.26 vs. 0.29±0.74 re-revisions; p=0.018). Conclusions. Patients of HV revision surgeons have better outcomes following full rTKA. These findings support the development of revision teams within arthroplasty centers of excellence to offer patients the best possible outcomes following rTKA

Aims. The aim of this study was to evaluate medium-term outcomes and complications of the S-ROM NOILES Rotating Hinge Knee System (DePuy, USA) in revision total knee arthroplasty (rTKA) at a tertiary unit. Methods. A retrospective consecutive study of all patients who underwent a rTKA using this implant from January 2005 to December 2018. Outcome measures included reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Results. A total of 89 consecutive patients (89 knees) were included with 47 females (52.8%) and a median age of 74 years (interquartile range 66 to 79). The main indications were aseptic loosening with instability (39.4%; n = 35) and infection (37.1%; n = 33) with the majority of patients managed through two-stage approach. The mean follow-up was 7.4 years (2 to 16). The overall rate of reoperation, for any cause, was 10.1% (n = 9) with a rate of implant revision of 6.7% (n = 6). Only two cases required surgery for patellofemoral complications. Kaplan-Meier implant-survivorship analysis was 93.3% at ten years, using revision for any cause as an endpoint. Conclusion. This implant achieved high ten-year survivorship with a low complication rate, particularly patellofemoral complications. These can be avoided by ensuring central patella tracking and appropriate tension of the patellofemoral joint in this posterior hinge design. Cite this article: Bone Jt Open 2022;3(3):205–210

Background. Revision total knee arthroplasty (rTKA) is a high stakes procedure with complex equipment and multiple steps. For rTKA using the ATTUNE system revising femoral and tibial components with sleeves and stems, there are over 240 pieces of equipment that require correct assembly at the appropriate time. Due to changing teams, work rotas, and the infrequency of rTKR, scrub nurses may encounter these operations infrequently and often rely heavily on company representatives to guide them. In turn, this delays and interrupts surgical efficiency and can result in error. This study investigates the impact of a fully immersive virtual reality (VR) curriculum on training scrub nurses in technical skills and knowledge of performing a complex rTKA, to improve efficiency and reduce error. Method. Ten orthopaedic scrub nurses were recruited and trained in four VR sessions over a 4-week period. Each VR session involved a guided mode, where participants were taught the steps of rTKA surgery by the simulator in a simulated operating theatre. The latter 3 sessions involved a guided mode followed by an unguided VR assessment. Outcome measures in the unguided assessment were related to procedural sequence, duration of surgery and efficiency of movement. Transfer of skills was assessed during a pre-training and post-training assessment, where participants completed multi-step instrument selection and assembly using the real equipment. A pre and post-training questionnaire assessed the participants knowledge, confidence and anxiety. Results. All participants reported orthopaedics as their primary speciality with mean of 6-years experience. 80% reported they are ‘sometimes’ required to scrub for operations in which they do not feel comfortable with the equipment. All participants improved across the 3 unguided sessions reducing their operative time by 47%, assistive prompts by 75%, dominant hand motion by 28% and head motion by 36%. This transferred into the real-world: Participants completed 11.3% of tasks correctly in pre-training compared to 83.5% correct in the timely selection and assembly of rTKA equipment, post-training. All participants reported increased confidence and reduced anxiety after the training. Conclusion. Unfamiliarity with orthopaedic procedures or equipment is common for scrub nurses and can impact surgical performance. VR training improves their understanding, technical skills and efficiency in complex rTKA. These VR-learnt skills translate into the physical environment. This has important implications on how scrub nurses can be trained remotely, asynchronously and safely to perform complex orthopaedic surgery

Over the last decade, the number of total knee arthroplasty (TKA) has risen over 125%. Numerous studies have established a relationship between obesity and complications in primary TKA. Interestingly, few studies have investigated medical and orthopaedic complications in obese patients undergoing revision TKA (RTKA). With the increasing number of RTKA and with the prevalence of obesity still on the rise, the study of obesity on complications following RTKA is indicated. We retrospectively reviewed 180 RTKA performed by a single surgeon done between August 2008 and June 2017. All patients who underwent RTKA were included, but revisions done with simultaneous extensor mechanism reconstruction and/or distal femur replacement were excluded since these procedures are technically more demanding. 154 revisions met our inclusion/exclusion criteriaes and were included in the final analysis. 81 patients were included in the non-obese group (BMI . The total number of orthopaedic complications in the obese group (46.6%) was significantly higher than in the non-obese group (27.2%) (OR=1.71) (p = 0.01). The number of infection was higher in the obese group (11%) than in the non-obese (6.2%) but this was not statistically significant (OR=1.77) (p = 0.28). Reoperation rate was also higher in the obese group (23.3%) than in the non-obese group (16%) but this did not reach statistical significance (OR=1.46) (p = 0.26) (Table 3). Medical complications were higher in the obese group (31.5% vs 19.8%) (OR=1.59) (p=0.09). According to the Dindo-Clavien classification, the obese group demonstrated a significantly higher rate of grade 3 or higher complications (p = 0.01). Obesity significantly increases the occurrence of orthopaedic complications following RTKA. Obesity also seems to increase the number of medical complications following RTKA. The obese patient should be informed prior to revision TKA that there is an increased risk of complications when compared with the non-obese patient. Further research with higher power would seem advisable to confirm this trend. For any figures or tables, please contact the authors directly

Introduction. Previous studies on Medicare populations have shown improved outcomes and decreased 90-day episode-of-care costs with robotic assisted total knee arthroplasty (rTKA). The purpose of this study was to evaluate the expenditures and utilization following rTKA in the under 65 y/o population. Methods. TKA procedures were identified using the OptumInsights Inc. database. A two-year window was studied. The procedures were stratified in two groups: the rTKA or manual (mTKA) cohorts. Propensity score matching (PSM) was performed at 1:5. Utilization and associated costs were analyzed for 90 days following the index procedure. 357 rTKA and 1785 mTKA were included in this analysis. Results. Within the 90 days following the surgery, patients who had robotic assisted procedures were less likely to utilize inpatient services (2.24 vs. 4.37%; p=0.0444) and skilled nursing visits (SNF) (1.68 vs. 6.05%; p<0.0001). No patients in the robotic TKA group went to inpatient rehab while 0.90% of the manual cases went to an inpatient rehabilitation facility. Patients who utilized a home health aide in the rTKA arm utilized significantly fewer days of home health (5.33 vs. 6.36 days; p=0.0037). Cost associated with the utilization of these services was lower in the rTKA arm; the overall post-surgery expenditures were $1,332 less in the rTKA arm ($6,857 vs. $8,189; p=0.0018). The 90-day global expenditures (index plus post-surgery) were $4,049 less in the rTKA arm ($28,204 vs. $32,253; p<0.0001). Lastly, length of stay (LOS) after surgery was nearly a day less for the rTKA arm (1.80 vs. 2.72 days; p<0.0001). Conclusion. Robotic assisted TKA was associated with shorter LOS, reduced utilization of services and reduced 90-day payer costs when compared to the manual TKA. For figures, tables, or references, please contact authors directly

Background. As the number of total knee arthroplasties (TKA) being performed continues to increase, the number of potential failures requiring revision surgery would also be expected to increase. This study analyzed the trends in revision TKA (rTKA) from 2009 to 2016. Methods. The Nationwide Inpatient Sample (NIS) database was used to identify all rTKA by International Classification of Diseases, Ninth Revision (ICD-9) and Tenth Revision (ICD-10) codes. The diagnoses leading to revision, revision costs, patient and hospital characteristics, and major inpatient complications were compared between 2009 and 2016. Multivariate logistic regression analyses were used to calculate odds ratios (OR) for complications. Results. A total of 453,770 rTKA were performed between 2009 and 2016 (Table 1). The incidence of rTKA between 2009 and 2016 decreased by 4.3% among all age groups and decreased 5.9% in those over 65 years of age. The mean age at revision remained unchanged at 65 years, the mean Length of Stay (LOS) decreased 19.5% from 4.1 to 3.3 days (p<0.001), and the mean hospital costs increased 18.7% from $23,103 to $27,427 (p<0.001). Male to Female ratio remained unchanged with Females making up 58% of rTKA. The rTKA patients in 2016 versus 2009 had significantly lower odds of requiring a blood transfusion (OR 0.26, p<0.001). The rate of myocardial infarction remained unchanged in 2016 versus 2009 (4.1% vs. 4.0%, p=0.52), as did mortality (0.1% vs. 0.2%, p=0.089). Patients in 2016 were significantly less likely to be discharged to a skilled nursing facility (SNF) (26.5% in 2016 vs. 31.6% in 2009, p<0.001). A significantly larger share of rTKA were performed in urban teaching hospitals in 2016 (66.6% in 2016 vs. 41.5% in 2009, p<0.001). Mechanical loosening remained the most common reason for rTKA and increased from 19.7% in 2009 to 28.4% in 2016. Infection remained the second most common reason for rTKA (14.7% in 2009 vs. 12.2% in 2016). Instability was the third most common reason for revision in 2016 (10.7%) but direct comparison with 2009 could not be made since ICD-9 did not include this diagnosis. When comparing 2009 to 2014, an increase in revision rates was noted. Upon inclusion of 2015 and 2016 data, a decrease is noted. The primary limitation of this study is the challenge faced when comparing results from before and after the October 2015 transition of ICD-9 to ICD-10 codes. Conclusions. The incidence of rTKA had decreased slightly between 2009 and 2016 even while the volume of primary TKA continued to rise. Implant loosening became increasingly prevalent as a reason for revision and infection continued to plague patients after TKA. Positive trends were noted, such as decreased rates of blood transfusion, LOS and rates of discharge to SNF. Still, the revision burden remains large, costing approximately $1.4 billion annually and we must continue to attempt to improve outcomes in this patient population. For figures, tables, or references, please contact authors directly

Abstract. Introduction. Choosing a hinged implant in the revision knee arthroplasty (rTKA) setting is challenging and limited data on implant performance exists. We present the survivorship and reason for failure in rTKA performed at our institution using the LINK hinge prosthesis, predominantly the cemented modular Endo-Model prosthesis. Methodology. 260 consecutive revision knee cases performed between 2012 and 2020 were reviewed retrospectively. Mean follow up was 27 months (range 0 to 107). Survivorship was analysed in Stata using a Log Rank test to compare performance in patients stratified according to age (≥80 years old (76 cases), 70–79 years (104 cases) and ≤70 years (80 cases). Results. 53 patients died and 48/207 (23%) cases in 40 patients underwent re-revision. Reasons for re-revision were aseptic loosening (21), infection (12), instability (4), extensor failure (1), stiffness (1), fracture (1) and other (8). Loosening was seen in the femur (8), tibia (5), and both the femur and tibia (8). Sub-group analysis of patients according to age showed a significantly higher failure rate in younger patients (6 failures (8%) in patients ≥80, 27 failures (26%) in 70–79 and 15 (19%) in ≤70 (p = 0.02). Failure in patients ≤70 was predominantly due to aseptic loosening (8/15). Conclusion. Here we report a significantly higher rate of LINK hinge prostheses failure in patients <70 undergoing rTKA. Consent should consider the risk of re-revision in this patient group

Sound management decisions are critical to outcomes in revision arthroplasty. Aiming to improve outcomes, revision networks facilitate speciality trained, high volume surgeons, share experience and best practice, contributing to decision making within and away from their base hospital. We have reported the early clinical experience of East Midlands Specialist Orthopaedic Network (EMSON). In this paper we report beneficial clinical effects, both demonstrable and unquantifiable supporting the process. Using the UK HES database of revisions, performed before and after EMSON was established, (April 2011 – March 2018), data from EMSON hospitals were compared to all other hospitals in the same time-period. Primary outcome was re-revision surgery within 1 year. Secondary outcomes were re-revision, complications within first two years and median LOS. 57,621 RTHA and 33,828 RTKA procedures were involved with around 1,485 (2.6%) and 1,028 (3.0%) respectively performed within EMSON. Re-revision THA rates, within 1 year, in EMSON were 7.3% and 6.0% with re-revision knee rates 11.6% and 7.4%, pre- and post-intervention. Re-revision rates in the rest England in the same periods were 7.4% to 6.8% for hips and 11.7% to 9.7% for knees. This constituted a significant improvement in 1-year re-revision rates for EMSON knees. (β = −0.072 (−0.133 to −0.01), p = 0.024). The reduction in hip re-revision did not reach statistical significance. Secondary outcomes showed a significant improvement for 1 and 2-year RTHA complication rates. Re-revision rates for RTKA and complication rates for RTHA improved significantly after the introduction of EMSON. Other outcomes studied also improved to a greater extent in the network hospitals. While anecdotal experience with networks is positive, the challenge in collating data to prove clinic benefit should not be underestimated. Beyond the formal process, additional communication, interaction, and support has immeasurable benefit in both elective and emergency scenarios

A primary goal of revision Total Knee Arthroplasty (rTKA) is restoration of the Joint Line (JL) and Posterior Condylar Offsets (PCO). The presence of a native contralateral joint allows JL and PCO to be inferred in a way that could account for patient-specific anatomical variations more accurately than current techniques. This study assesses bilateral distal femoral symmetry in the context of defining targets for restoration of JL and PCO in rTKA. 566 pre-operative CTs for bilateral TKAs were segmented and landmarked by two engineers. Landmarks were taken on both femurs at the medial and lateral epicondyles, distal and posterior condyles and hip and femoral centres. These landmarks were used to calculate the distal and posterior offsets on the medial and lateral sides (MDO, MPO, LDO, LPO respectively), the lateral distal femoral angle (LDFA), TEA to PCA angle (TEAtoPCA) and anatomic to mechanical axis angle (AAtoMA). Mean bilateral differences in these measures were calculated and cases were categorised according to the amount of asymmetry. The database analysed included 54.9% (311) females with a mean population age of 68.8 (±7.8) years. The mean bilateral difference for each measure was: LDFA 1.4° (±1.0), TEAtoPCA 1.3° (±0.9), AAtoMA 0.5° (±0.5), MDO 1.4mm (±1.1), MPO 1.0mm (±0.8). The categorisation of asymmetry for each measure was: LDFA had 39.9% of cases with <1° bilateral difference and 92.4% with <3° bilateral difference, TEAtoPCA had 45.8% <1° and 96.6% <3°, AAtoMA had 85.7% <1° and 99.8% <3°, MDO had 46.2% <1mm and 90.3% <3mm, MPO had 57.0% <1mm and 97.9% <3mm. This study presents evidence supporting bilateral distal femoral symmetry. Using the contralateral anatomy to obtain estimates for JL and PCO in rTKA may result in improvements in intraoperative accuracy compared to current techniques and a more patient specific solution to operative planning

Purpose. Unexpected-positive-intraoperative-cultures (UPIC) in presumed aseptic revision-total-knee-arthroplasties (rTKA) are common, and the clinical significance is not entirely clear. In contrast, in some presumably septic rTKA, an identification of an underlying pathogen was not possible, so called unexpected-negative-intraoperative-cultures (UNIC). The purpose of this study was to evaluate alpha defensin (AD) levels in these patient populations. Methods. In this retrospective analysis of our prospectively maintained biobank, we evaluated synovial AD levels from 143 rTKAs. The 2018-Musculoskeletal Infection Society score (MSIS) was used to define our study groups. Overall, 20 rTKA with UPIC with a minimum of one positive intraoperative culture with MSIS 2-≥6 and 14 UNIC samples with MSIS≥6 were compared to 34 septic culture-positive samples (MSIS ≥6) and 75 aseptic culture-negative (MSIS 0–1) rTKAs. Moreover, we compared the performance of both AD-lateral-flow-assay (ADLF) and an enzyme-linked-immunosorbent-assay (ELISA) to test the presence of AD in native and centrifuged synovial fluid. Concentration of AD determined by ELISA and ADLF methods, as well as microbiological, and histopathological results, serum and synovial parameters along with demographic factors were considered. Results. AD was detected in 31/34 (91.2%) samples from the infected-group and in 14/14 (100%) samples in the UNIC group. All UPIC samples showed a negative AD result. Positive AD samples were highly (p<0.001) associated with culture positive and infection related histopathological results. Moreover, we found significantly (p=0.001) more high-virulent microorganisms 19/34 (55.9%) in the infected-group compared to the UPIC-group (0/20). Samples from the infected group with high virulent microorganisms 17/19 (89.5%) showed a positive AD. The presence of methicillin resistant Staphylococcus epidermis (MRSE) led to increased AD (p=0.003) levels when compared to those determined in samples positive for methicillin susceptible S. epidermdis (MSSE). ELISA and ADLF tests were positive with centrifuged (8/8) and native (8/8) synovial fluid. Conclusion. AD showed a solid diagnostic performance in infected and non-infected revisions, and it provided an additional value in the diagnostic of UPIC and UNIC associated to rTKAs. AD levels produced by patients with PJIs caused by high-virulent microorganisms and MRSE are significantly higher compared to those in patients with PJIs caused by either low-virulent or antibiotic susceptible microorganisms. Centrifugation of synovial fluid had no influence in the outcome of ADLF quantification. Keywords: Alpha-defensin, UPIC, UNIC, revision-knee-arthroplasty

Introduction. The purpose of this study is to compare total and rate of caloric energy expenditure between conventional and robotic-arm assisted total knee arthroplasty (TKA) between a high volume “veteran” surgeon (HV) and a lower volume, less experienced surgeon (LV). Methods. Two specialized arthroplasty surgeons wore a biometric-enabled shirt and energy expenditure outcomes were measured (total caloric expenditure, kilocalories per minute, heart rate variability, and surgical duration) during 35 conventional (CTKA) and 29 robotic primary total knee arthroplasty (RTKA) procedures. Results. Overall, the rate of caloric expenditure was similar between RTKA (5.60 ±2.50 kcal/min) and CTKA (4.79cal/min ±1.79, p=0.25). With 6.15 minute longer operative times, the total energy expenditure (TEE) for RTKA (239.31±96.79 kcal) was higher thanCTKA(181.54 ±80.90 kcal, p<0.001). The HV surgeon's TEE (p<0.001) and rate of energy expenditure (REE) (p<0.001) were significantly higher in RTKA (261.53cal; 6.499cal/min) versus CTKA (71.00cal; 3.759cal/min). However, the LV surgeon's TEE and REE for RTKA (207.83cal; 4.32cal/min) and CTKA (195.81cal; 4.92cal/min) were not significantly different (p>0.05). Both surgeons (HV; LV) had significantly longer surgical durations (p<0.001) in RTKA (40.41 ±4.94min; 48.91 ±8.45min) compared to CTKA surgeries (18.75±4.27min; 40.4 ±8.34min), respectively. Conclusion. While REE did not varybetween CTKA and RTKA for the LV surgeon, it did vary significantly for the HV surgeon. Additionally, RTKA took longer and increased TEE, but one less operating room assistant was needed. Surgeons with less experience in TKA may be less likely to notice a difference in energy expenditure when utilizing robotic-arm assisted technology. It is possible that more experience with using the robotic arm could create efficiencies over time that may also reduce TEE

Introduction. Robotic-arm total knee arthroplasty (RTKA) was developed to potentially improve accuracy of bone cuts, component alignment, soft tissue balance, and patient outcomes. There is a paucity of data demonstrating that RTKA is superior to conventional total knee arthroplasty (CTKA) in terms of any of these metrics. This prospective comparative multicenter study was designed with these purposes in mind. Methods. Patients were enrolled between June 1st, 2016 and March 31st, 2018 in a prospective, non-randomized, open-label, multicenter, consecutive comparative cohort study comparing RTKA and CTKA. Only patients who satisfied the following inclusion criteria were included: body mass index (BMI) ≤ 40kg/m2, primary unilateral TKA procedure, at least 18 years of age, and no joint infection. The following data were collected for analysis:. Preoperative data on component size prediction from CT scans. Intraoperative data on bone resection levels and joint line maintenance. Functional activity scores, patient-reported symptoms, satisfaction and expectation scores using The New Knee Society Scoring System. Radiographic results, specifically coronal alignment. Results. For femoral components implanted, 82% were the exact size as predicted by the robotic-software and the remaining 18% were within 1 size (100% within 1 size). For tibial implants, 69% were the exact size of what the robotic-software predicted and 29% were within 1 size (98% within 1 size). RTKAs had significantly less distal lateral femoral resection (5.55 vs. 7.11 mm), distal medial femoral resection (6.89 vs. 7.97 mm), lateral tibial resection (7.76 vs. 8.54 mm), and medial tibial resection (4.11 vs. 5.56 mm, p<0.05) compared to CTKA. Joint line restoration was comparable between RTKA and CTKA, but required less tibial bone removal when using robotic techniques. Pre-operatively, all demographic, functional, symptom, satisfaction, and expectation measures were similar between treatment groups (all p<0.05, Tables 1–5). Those who underwent RTKA had significantly higher mean functional activity walking and standing score improvements from baseline to 4–6 weeks (1.4 vs. −1.2 points; p=0.019) and to 6 months (9.6 vs. 6.9 points; p=0.017) after surgery compared to CTKA. The mean overall functional activity score improvement from baseline to 1-year post-surgery was also higher for RTKA compared to CTKA (36.8 vs. 15.0 points; p=0.020). For all other parameters (standard activities, advanced activities, pain with walking, pain with stairs, satisfaction and expectation scores), score changes from baseline were not significantly different between groups, though many trended slightly higher for RTKA. Radiographic evaluation of RTKA demonstrated that varus deformity was corrected to neutral in 96% of cases and valgus deformity was corrected in 100%. Conclusion. To the best of our knowledge, this is the first study to prospectively evaluate outcomes of RTKA patients compared to CTKA. A number of positive early effects were seen with RTKA. This patient cohort will continue to be followed, and these findings may translate into longer-term patient reported outcomes improvement, longer component survivorship and cost savings. For any figures or tables, please contact authors directly

During revision total knee arthroplasty (rTKA), proximal tibial bone loss is frequently encountered and can result in a less-stable bone-implant fixation. A 3D printed titanium alloy (Ti6Al4V) revision augment that conforms to the irregular shape of the proximal tibia was recently developed. The purpose of this study was to evaluate the fixation stability of rTKA with this augment in comparison to conventional cemented rTKA. Eleven pairs of thawed fresh-frozen cadaveric tibias (22 tibias) were potted in custom fixtures. Primary total knee arthroplasty (pTKA) surgery was performed on all tibias. Fixation stability testing was conducted using a three-stage eccentric loading protocol. Static eccentric (70% medial/ 30% lateral) loading of 2100 N was applied to the implants before and after subjecting them to 5×103 loading cycles of 700 N at 2 Hz using a joint motion simulator. Bone-implant micromotion was measured using a high-resolution optical system. The pTKA were removed. The proximal tibial bone defect was measured. One tibia from each pair was randomly allocated to the experimental group, and rTKA was performed with a titanium augment printed using selective laser melting. The contralateral side was assigned to the control group (revision with fully cemented stems). The three-stage eccentric loading protocol was used to test the revision TKAs. Independent t-tests were used to compare the micromotion between the two groups. After revision TKA, the mean micromotion was 23.1μm ± 26.2μm in the control group and 12.9μm ± 22.2μm in the experimental group. There was significantly less micromotion in the experimental group (p= 0.04). Prior to revision surgery, the control and experimental group had no significant difference in primary TKA micromotion (p= 0.19) and tibial bone loss (p= 0.37). This study suggests that early fixation stability of revision TKA with the novel 3D printed titanium augment is significantly better then the conventional fully cemented rTKA. The early press-fit fixation of the augment is likely sufficient for promoting bony ingrowth of the augment in vivo. Further studies are needed to investigate the long-term in-vivo fixation of the novel 3D printed augment

Introduction. Robotic assisted Total Knee Arthroplasty (rTKA), provides surgeons with preoperative planning and real-time data allowing for continuous assessment of ligamentous tension and range-of-motion. Using this technology, soft tissue protection, reduced early post-operative pain and improved patient satisfaction have been shown. These advances have the potential to enhance surgical outcomes and may also reduce episode-of-care (EOC) costs for patients, payers, and hospitals. The purpose of this study was to compare robotic assisted vs. manual total knee arthroplasty: 1) 90-day episode-of-care (EOC) costs; 2) index costs; 3) lengths-of-stay (LOS); 4) discharge disposition; and 5) readmission rates. Methods. TKA procedures were identified using the Medicare 100% Standard Analytic Files including; Inpatient, Outpatient, Skilled Nursing (SNF) and Home Health. Members included patients with rTKA or manual TKA (mTKA) between 1/1/2016-3/31/2017. To account for potential baseline differences, propensity score matching (PSM) was performed in a 1-to-5 ratio, robotic to manual based on age, sex, race, geographic division, and comorbidities. After PSM, 519 rTKA and 2,595 mTKA were identified and included for analysis. Ninety-day episode-of-care cost, index cost, LOS, discharge disposition and readmission rates were assessed. Results. Overall 90-day EOC costs were $2,391 less for rTKA patients ($18,568 vs. $20,960; p<.0001). Index facility cost and LOS were also less for rTKA patients by $640 ($12,384 vs. $13,024; p=.0001) and 0.7 days (p<.0001). Additionally, rTKA patients were discharged to SNF less frequently (12.52% vs. 21.70%; p<.0001) and home with health aid (56.65% vs. 46.67%; p<.0001) or self-care (27.55% vs. 23.62%; p=.0566) more frequently and had a 90-day readmission reduction of 33% (p=.0423). Conclusion. Robotic assisted TKA resulted in an overall lower 90-day episode-of-care cost when compared to manual TKA. The 90-day EOC cost savings of rTKA were driven by reduced facility costs, LOS and readmissions, and an economically beneficial discharge destination

Aim. This was a multicenter, randomized, clinical trial to compare the 90-day 1) incidence of surgical site complications (SSC); 2) health care utilization (the number of dressing changes, readmission, and reoperation); and 3) the patient-reported outcomes (PRO) in high-risk patients undergoing revision total knee arthroplasty (rTKA) with postoperative closed incision negative pressure wound therapy (ciNPT) versus a standard of care (SOC) silver-impregnated occlusive dressing. Method. A total of 294 rTKA patients (15 centers) at high-risk for wound complications were prospectively randomized to receive either SOC or ciNPT (n = 147 each). The ciNPT system was adjusted at 125 mmHg of suction. Investigated outcomes were assessed weekly up to 90 days after surgery. A preset interim analysis was conducted at 50% of the intended sample size, with planned discontinuation for clear efficacy/harm if a significance of p < 0.005 was attained. Results. A total of 242 patients completed the required follow-up (ciNPT: n = 124 (84.4%); SOC: n = 118 (80.3%)). Demographics, baseline comorbidities, causes of revision (prosthetic joint infection, aseptic loosening, implant-related, and periprosthetic fractures), and duration of treatment were similar in both cohorts (p > 0.05). Intention to treat analysis demonstrated lower rates of SSC with ciNPT (3.4%) compared to SOC (14.3%) (p = 0.0013) (Table 1 – not included in the proceeding). Similar outcomes were obtained with the modified intention to treat analysis (p = 0.0013). The ciNPT cohort exhibited lower readmission rates (p = 0.0208), and number of dressing changes (p = 0.0003). Conversely, differences in the 90-day incidence of SSI and measured patient-reported outcomes did not reach statistical significance (p > 0.05). Conclusions. ciNPT mitigates the risk of SSC and readmission among high-risk rTKA patients. The lower frequency of dressing changes within the ciNPT cohort may provide added value for healthcare utilization without compromising pain and function. For the table, please contact authors directly

Revision Total Knee Arthroplasty (rTKA) is predicted to increase by more than 600% between 2005 and 2030. The survivorship of primary TKA has been extensively investigated, however more granular information on the risks of rTKA is needed. The aim of the study was to investigate the incidence of re-revision TKA, with explanatory variables of time from primary to revision, and indication (aseptic vs septic). Secondary aim was to investigate mortality. This is an analysis of the Scottish Arthroplasty Project data set, a national audit prospectively recording data on all joint replacements performed in Scotland. The period from 2000 to 2019 was studied. 4723 patients underwent revision TKA. The relationship between time from primary to revision TKA and 2nd revision was significant (p<0.001), with increasing time lowering probability of re-revision (OR 0.99 95% CI 0.987 to 0.993). There was no significant association in time to first revision on time from 1st revision to re-revision (p>0.05). Overall mortality for all patients was 32% at 10 years (95% CI 31-34), Time from primary TKA to revision TKA had a significant effect on mortality: p=0.004 OR 1.03 (1.01-1.05). Septic revisions had a reduced mortality compared to aseptic, OR 0.95 (0.71-1.25) however this was not significant (p=0.69). This is the first study to demonstrate time from primary TKA to revision TKA having a significant effect on probability of re-revision TKA. Furthermore the study suggests mortality is increased with increasing time from primary procedure to revision, however decreased if the indication is septic rather than aseptic

INTRODUCTION. As the demographic of the patient population requiring revision total knee arthroplasty (rTKA) continues to expand, varying preoperative conditions and activity levels need to be taken into consideration when analyzing postoperative outcomes. Factoring in preoperative activity levels can help manage the expectations of patients. The purpose of this study was to analyze the outcomes of low and high activity patients receiving a contemporary rTKA. METHODS. One hundred and eighty rTKA patients enrolled in a prospective, multicenter study were evaluated through 2 years postoperative. Patients were divided into groups based on preoperative activity level using the Lower Extremity Activity Scale (LEAS). Patients scoring between 1–7 were classified as ‘Low Activity’ (LA, N=104) and patients scoring 8–18 were classified as ‘High Activity’ (HA, N=76). Clinical and patient-reported outcomes were evaluated, with an additional quality of life analysis completed utilizing SF-6D scores obtained by transforming SF-36 scores through a method described by Brazier et al. and analyzed for effect size. RESULTS. No differences were seen in age or BMI between the groups, with more females in the LA group (64%) and majority males in the HA group (58%). Both groups displayed statistically significant improvements through 2 years; however the degree of improvement varied based on outcome measure. Postoperative improvement in both groups were similar in the KSS, but patients in the LA group showed larger increases in the KSS Functional assessment at 6 weeks and 2 years (Figure 1). The effect of rTKA was analyzed through an SF-6D analysis (Figure 2). There was a statistically significant large effect seen in the LA group at 1 year (0.96), which was in conjunction with a higher SF-6D outcome (Figure 2). CONCLUSION. The current study population displayed significant improvement in functional patient outcomes following rTKA regardless of preoperative activity level and function. Patients with lower preoperative activity levels demonstrated not only greater cumulative functional improvements, but also had significant improvements in quality of life following rTKA. This suggests that the preoperative lower activity level may be in part related to the poorly functioning knee and that revision surgery has the potential to improve overall activity levels and function

Background. Revision total knee arthroplasty (rTKA) is a complex procedure with increased risk of blood loss and transfusions. The Musculoskeletal Infection Society has included D-dimer as a serology marker for peri-prosthetic infection. The study's intent is to understand the impact of preoperative D-dimer levels on blood loss and venous thromboembolism in revision TKA. Methods. Following IRB approval, rTKA performed by a single surgeon between January 1, 2017 and December 31, 2019 were reviewed. Inclusion criteria consisted of pre-operative D-Dimer, cemented revision TKA of one or both components under tourniquet control. 89 patients met the criteria including 37 males (41.6%) and 52 females (58.4%). Mean ages were 65 for males and 67 for females. The data revealed 54 patients (61%) had an elevated D-dimer (group 1) and 35 patients (39%) had a normal D-dimer (group 2). Sex stratification showed 21 males (57.8%) and 33 females (63.5%) with elevated D-dimer. TXA protocol included 2 grams intravenous (82 patients) or 2 grams intra-articular application (7 patients). Post-operative anticoagulation included Lovenox 40mg daily for 2 weeks followed by aspirin 325 twice daily for 4 weeks. Pre-operative and post-operative hemoglobin, transfusion rates and post-operative VTE within 90 days of surgery were recorded. Results. The mean pre-operative hemoglobin (hgb) was 13.30 and post-operative was 11.21. The mean change in hgb for males was 2.75 and for females 1.91. Both male and female cohorts had an acceptable range and the change in hgb was not statistically significant (p=0.076). Two female patients (2.25%) were transfused, both receiving IV TXA and their pre-operative hgb was lower than the cohort. No VTE events were identified in either groups of patients within the 90 day post-operative period. Conclusion. This study revealed that TXA is effective in reducing blood loss following rTKA and an elevated D-dimer is not a contraindication to its use

Aim. Bone loss is a severe problem in septic revision total knee arthroplasty (RTKA). The use of porous coated metaphyseal sleeves is a promising treatment option for extended bone defects. The currently published mid-term results remain limited and no study has been focused exclusively on septic cases. Our aim was to determine the implant survivorship (with special focus on osseointegration) and the clinical and radiological mid-term outcome of metaphyseal sleeve fixation in septic RTKA surgery (minimum follow-up of 2 years). Method. Between January 2005 and September 2015, 57 patients underwent septic RTKA surgery using metaphyseal sleeves. In 56 patients (98,2 %) who underwent a total of 69 two stage revision procedures, clinical and radiological follow-up examinations were conducted. One patient (1,8 %) was lost to follow-up. The examinations included the American Knee Society Score (KSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the SF-36 Health survey as well as radiographic measurement to determine if successful osseointegration had been achieved. Results. Thirteen knees (18.8%) had to be re-revised at the time of follow-up (mean 5.3 years, min. 2 – max. 11.2), all due to reinfection (Figure 1). We did not encounter any cases of aseptic loosening. The mean range of motion (92° ± 21°), SSS (7 ± 2), KSS (76 ± 19), WOMAC (70 ± 20), SF-36 MCS (55 ± 14) and SF-36 PCS (35 ± 9) have shown satisfying results. Conclusions. Metaphyseal sleeves have shown very promising mid-term results regarding clinical scores, osseointegration, and aseptic loosening. Our results are the first analysing the performance of metaphyseal sleeves in exclusively septic cases and show that they are a reliable fixation option in septic RTKA patients with severe bone loss

Aim. Serum parameters continue to be a focus of research in diagnosing periprosthetic joint infections (PJI). Several workgroups have recently proposed serum Albumin-Globulin-Ratio (AGR) as a potential new biomarker. Due to controversies in the literature, its usability in clinical practice remains uncertain. The aim of this study was to assess the value of serum AGR in diagnosing PJI preoperatively, especially in comparison with the well-established marker C-reactive Protein (CRP). Method. From January 2015 to June 2022, patients with indicated revision hip (rTHA) and knee (rTKA) arthroplasty were included in this retrospective cohort study of prospectively collected data. A standardized diagnostic workup was performed using the 2021 European Bone and Joint Infection Society (EBJIS) definition of PJI, excluding CRP. Diagnostic accuracies of serum AGR and CRP were calculated by receiver operating characteristic curve (ROC) analysis. A z-test was used to compare the area under the curves (AUC). Results. A total of 275 patients with rTHA and rTKA were included, 144 joints (52.4%) were identified as septic. Decreased AGR and elevated CRP were strongly associated with PJI, optimal diagnostic thresholds were calculated with 1.253 and 9.4 mg/L, respectively. Sensitivities were 62.5% (95%-confidence interval: 54.3–70.0) and 73.6% (65.8–80.1), and specificities 84.7% (77.5–89.9) and 87.8% (80.9–92.4), respectively. CRP showed a significantly higher AUC than AGR (0.807 (0.761–0.853) and 0.736 (0.686–0.786); p<0.0001). Subgroup analysis of acute versus chronic infections yielded significantly higher diagnostic accuracies in acute PJI for both parameters (p<0.0001). Similar results were observed when focusing on the causative microorganism; a better diagnostic performance was observed in high-virulence PJI compared to low-virulence PJI (p≤0.005). Furthermore, higher AUCs were calculated in knee PJI compared with hip PJI, with a significant difference for AGR (p=0.043). Conclusions. Due to its limited diagnostic accuracy, serum AGR cannot be recommended as an additional marker for diagnosing PJI. Serum parameters are generally unspecific and can be influenced by comorbidities and other foci of infection. Additionally, parameters may remain within normal levels in low-grade PJI. Evaluating AGR, further possible pitfalls must be considered, for example an increased latency until bottom values are reached and the impact of malnutrition

Aim. One of the most challenging problems in total knee arthroplasty (TKA) is periprosthetic infection. A major problem that arises in septic revision TKA (RTKA) are extended bone defects. In case of extended bone defects revision prostheses with metaphyseal sleeves are used. Only a few studies have been published on the use of metaphyseal sleeves in RTKA - none were septic exclusive. The aim of our study was to determine the implant survival, achieved osseointegration as well as the radiological mid-term outcomes of metaphyseal sleeve fixation in septic two-stage knee revision surgery. Method. Clinical and radiological follow-up examinations were performed in 49 patients (25 male and 24 female). All patients were treated with a two-stage procedure, using a temporary non-articulating bone cement spacer. The spacer was explanted after a median of 12 weeks (SD 5, min. 1 – max. 31) and reimplantation was performed, using metaphyseal sleeves in combination with stem fixation. Bone defects were classified on preoperative radiographs using the Anderson Orthopaedic Research Institute (AORI) classification. During follow-up postoperative range of motion (ROM) was measured and radiographs were performed to analyse: (i) osseointegration (radiolucent lines and spot welds), (ii) leg alignment, (iii) patella tilt and shift. Results. All types of bone defects were found on the tibial (4× type 1, 7× type 2a, 26× type 2b, 9× type 3) as well as on the femoral side (1× type 1, 4× type 2a, 20× type 2b, 6× type 3). Mean follow-up time was 4.7 years (minimum 1 year). In total 12 knees (24.5%) had to be re-revised, all due to re-infection. We did not encounter any case of aseptic loosening. In 3 patients (6.8%) we detected an insufficient osseointegration, but no patient had to be re-revised due to only minimal or to the absence of symptoms and no clinical signs of loosening. The ROM (mean 93°, SD 20.6, min. 25° max. 125°) has shown very satisfying results at the time of follow-up. Malalignment was detected in 4 patients (10.3%), a patella tilt in 7 (19.4%) and a patella shift in 14 (48.3%). Conclusions. Metaphyseal Sleeves have shown very promising mid-term results regarding osseointegration and aseptic implant survival in RTKA with compromised metaphyseal bone stock. Our results indicate that they are a reliable fixation option in septic RTKA patients

Background. Revision total knee arthroplasties (rTKA) are performed with increasing frequency due to the increasing numbers of primary arthroplasties, but very little is known regarding the influence of muscle strength impairments on functional limitations in this population. Objectives. The aim of this study was to assess relationship between muscle strength and functional level in patient with rTKA. Design and Methods. Twenty-three patients (8 males, 15 females) were included in the study with mean age 68.4±10 years. Patients performed 3 performance tests (50-Step Walking Test, 10 Meter Walk Test, 30-Second Chair-Stand Test), and one self-report test (HSS) were preferred to assess patients. The maximum isometric muscle strength of quadriceps femoris and hamstring muscles of all the patients was measured using Hand-Held Dynamometer (HHD). Results. While moderate-to-strong significant correlations was found between quadriceps femoris muscle strength and 30- Second Chair-Stand Test (r=0.390, p=0.049), 50-Step Walking Test (r=−0.530, p=0.005), 10 Meter Walk Test (r=−0.587, p=0.002), there were not significant correlation between HSS knee score and all performance-based tests (p>0.05). Also there were not significant correlation between hamstring muscle strength and all other measurement tests (p>0.05). Conclusion. The moderate-to-strong statistical significant correlation between quadriceps femoris muscle strength and functional performance tests suggests that improved postoperative quadriceps strengthening could be important to enhance the potential benefits of rTKA

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

Purpose: To determine mortality and morbidity for bilateral total knee replacment compared to unilateral knee replacement and revision total knee replacement using the National National Hospital Discharge Survey to include large numbers of patients and look at outcomes. Method: We analyzed nationally representative data to elucidate the demographics, comorbidities, hospital stay, in-hospital complications and mortality of patients undergoing BTKA and compared them with those of patients undergoing UTKA and revision TKA (RTKA). Data in the National Hospital Discharge Survey on hospital discharges with procedure codes for BTKA, UTKA and RTKA between 1990 and 2004 was analyzed. The demographics, comorbidities, in-hospital stay, complications and mortality were studied. We identified 4,169,489 discharges (153,259 BTKAs; 3,677,161 UTKAs; and 339,069 RTKAs). Results: Patients undergoing BTKA were younger (1.5 years) and had a lower prevalence of comorbidities for hypertension (vs. UTKA), diabetes, lung disease, and coronary artery disease (vs. UTKA and RTKA). The length of hospitalization was 5.8 days for BTKA, 5.28 for UTKA, and 5.41 for RTKA. Despite similar length of hospitalization, the prevalence of procedure related complications was higher for BTKA (14.17%+/−0.76 (SE)) than for UTKA (9.01%+/−0.17) and RTKA (9.84%+/−0.57). In hospital mortality was highest for BTKA patients (BTKA: 0.47%+/−0.15%; UTKA: 0.30%+/−0.03; RTKA: 0.27%+/−0.09). Conclusion: Despite younger age and lower comorbidity burden, patients undergoing BTKA had an approximately 1.6 times higher rate of procedure related complications and mortality compared to those undergoing UTKA. Outcomes for RTKA patients for most variables were similar to those for UTKA. In a multivariate analysis, BTKA, advanced age and male gender were independent risk factors for complications and mortality following TKA surgery

As the numbers of revision total knee arthroplasty (RTKA) rise, we continually need current information regarding the etiology/modes of failure and functional disability of patients presenting for RTKA. We used a prospective cohort study to assess these fundamental aspects of RTKA. 290 consecutive subjects presenting for RTKA had relevant clinical information, including modes of failure, collected from surgeon-completed documents. Patients themselves also completed quality of life and functional questionnaires, including the SF-36 and WOMAC Osteoarthritis Index. Mean patient age was 68.6 years (55 to 79 years). Mean SF-36 and WOMAC score at baseline indicated significant functional disability. The mean time from primary procedure to RTKA was 7.9 years (6 months to 27 years). Our series included 31 percent ‘early’ (under 2 years) revisions and 69 percent ‘late’ revisions. Sepsis was the cause of 10.4 percent revisions. The tibia needed revision in 78 percent, femur in 71 percent and patella in 31 percent of cases. The predominant modes of failure (non-exclusive frequency values as patients could have more than one cause) were (in percentages): instability (28.9), malalignment (27.5), tibial osteolysis (27.5), polyethylene wear (24.5), femoral osteolysis (22.5) and tibial loosening (22.2). These patients are relatively young, and considerably disabled by their failed primary procedure. Many modes of failure are within surgical control and direct us toward improved techniques and approaches. Other modes confirm the need for continued development of implants and materials. Information gained here will allow better formulation of measures and resource allocation that may prevent RTKAs

Purpose: Comorbidities in patients undergoing total joint arthroplasty continue to be a challenging problem. Retrospective studies have demonstrated that co-morbidities affect outcomes of revision total knee arthroplasty (RTKA). However, the relationship between the outcomes of RTKA and co-morbidities has not been well established. This prospective randomized study was undertaken to investigate these relationships. Method: A prospective cohort study (the North America Knee Arthroplasty Revision Study) was conducted to examine factors that predict outcomes after RTKA. 308 subjects met inclusion/exclusion criteria. Subjects were followed from the time of the index surgery for a minimum of two years to monitor outcomes and complications. Validated quality of life instruments, including SF-36, WOMAC, Knee Society Score, and an activity scale were used. The rates of improvement from 0 to 12 and 12 to 24 months were analyzed. Results: There were 145 males and 163 females. The mean age was 68.7 years. Mean time from primary procedure to RTKA was 7.9 years. Arthroplasty failure was classified as aseptic in 82% and septic in 18% of the cases. Hypertension was seen in 62.4%, back pain in 50%, heart disease in 25.9%, diabetes mellitus in 23.9%, gastric ulcers in 17.9%, and rheumatoid arthritis in 16.6%. Less frequent co-morbidities included anemia, cancer, kidney disease, lung disease and liver disease. Conclusion: Analyses showed that the number of reported co-morbidities was the most significant predictor of outcomes, consistently forecasting poorer functional improvement on all measures. The results indicated that ultimate treatment of co-morbidities before and after surgery may improve outcomes of RTKA. Comorbidities in patients undergoing revision TKA can be a challenging problem. This study showed that the number of reported co-morbidities was the most significant predictor of poorer outcomes

Aims: In Revision Total Knee Arthroplasty (RTKA), bone deficiencies and lack of anatomical references make it difficult to understand the normal knee kinematic and adequately plan the intervention. To our knowledge there are no data about computer assisted navigation system specifically developed for RTKA in the literature and existing navigated techniques for RTKA use navigation systems developed for primary TKA. A new computer assisted technique for RTKA is presented. Methods: This technique is based on the use of a navigation system, RTKANav consisting of an optical localizer, a dedicated software and some navigated tools specifically done for RTKA. The system doesn’t use medical images, and patient anatomy model is represented with dots and lines corresponding to acquired landmarks, providing the surgeon with the main references for the intervention monitored in real-time. During the most critical steps of the intervention (soft tissue balancing and the consequent choice of implant size, and joint line height restoration), the system provide the surgeon with graphical and numerical tools to improve the surgical outcome. Several criteria to set each degree of freedom of prosthetic components are considered and compared, and even if some required landmarks can not be identified, the system is always able suggest an intervention plan. The surgeon is provided with tools to analyze and modify the proposed plan, and to reproduce it on the patient. Results: Till now the presented technique was used on five patients by an expert surgeon. Qualitative results, collected after the intervention through a questionnaire on surgeon feelings, in order to assess the functionality, user friendliness and the data visualization criteria implemented were very satisfying. System reliability was assessed intraoperatively analyzing joint line height, limb alignment and knee stability using trial components: based on his experience, the surgeon checked some acceptable components combination and compared the corresponding outcome with the one provided by the implant planned by the system. In three out five cases the suggested implant was considered the best by the surgeon, while in one case he decided to change the tibial insert of one size because of knee instability and in another case he changed the tibial component of one size because the planned one was too small. Final limb alignment evaluated with postoperative x-rays, was satisfactory in all cases. Conclusions: Presented navigation system showed early promising results providing the surgeon with intraoperative quantitative and qualitative information on the main surgical parameters, useful to achieve a satisfactory prosthesis implant. Moreover this system use anatomical patient specific landmarks acquired after prosthesys removal, while navigation systems developed for primary TKA use both reference taken from preoperative x-rays and anatomical references acquired on metal component to be removed. Therefore in this case the operation planning is based on rough anatomical landmarks that do not reflect patients original anatomy

Aim. Despite several synovial fluid biomarkers for diagnosis of periprosthetic joint infection (PJI) have being investigated, point-of-care (POC) tests using these biomarkers are not widely available. Synovial calprotectin has recently been reported to effectively exclude diagnosis of PJI and a novel lateral flow POC test using it has shown potential to be effective. Thus, the aims of this study were to 1) validate calprotectin POC with enzyme linked immunosorbet assay (ELISA) 2) at 2 separate thresholds for PJI diagnosis in total knee arthroplasty (TKA) patients using the 2013 Musculoskeletal Infection Society (MSIS) PJI diagnosis criteria as the gold standard. Method. Intraoperative synovial fluid samples were prospectively collected from 123 patients who underwent revision TKAs (rTKA) at two academic hospitals within the same healthcare system from October 2018 to January 2020. The study was conducted under IRB approval. Included patients followed the hospital standard for their PJI diagnostic work-up. Data collection included demographic, clinical, and laboratory data in compliance with MSIS criteria. Synovial fluid samples were analysed by calprotectin POC and ELISA tests in accordance with manufacturer's instructions. Patients were categorized as septic or aseptic using MSIS criteria by two independent reviewers blinded to calprotectin assay results. The calprotectin POC and ELISA test performance characteristics were calculated with sensitivities, specificities, positive, and negative predicted values (PPV and NPV, respectively) and areas under the curve (AUC) for 2 different PJI diagnosis scenarios: (1) a threshold of >50 mg/L and (2) a threshold of >14 mg/L. Results. According to MSIS criteria, 53 rTKAs were septic while 70 rTKA were aseptic. In the (1) >50 mg/mL threshold scenario, the calprotectin POC and ELISA performance showed 100% agreement with sensitivity, specificity, PPV, NPV, and AUC, respectively, of 98.1%, 95.7%, 94.5%, 98.5%, and 0.969. In the (2) >14 mg/mL threshold scenario, the POC slightly outperformed the ELISA with sensitivity, specificity, PPV, NPV and AUC of 98.1%, 87.1%, 85.2%, 98.4%, and 0.926, respectively (ELISA values were 98.1%, 82.9%, 81.3%, 98.3%, and 0.905, respectively). Conclusions. The calprotectin POC test performed as well as the ELISA at the >50mg/L threshold and was slightly better at the >14 mg/L threshold. The >50 mg/L threshold had a better specificity while maintaining the same sensitivity as the >14 mg/L threshold. This test could be effectively implemented as a rule out test. However, further investigations with larger cohorts are necessary to validate these results

The April 2023 Knee Roundup³⁶⁰ looks at: Does bariatric surgery reduce complications after total knee arthroplasty?; Mid-flexion stability in total knee arthroplasties implanted with kinematic alignment: posterior-stabilized versus medial-stabilized implants; Inflammatory response in robotic-arm-assisted versus conventional jig-based total knee arthroplasty; Journey II bicruciate stabilized (JII-BCS) and GENESIS II total knee arthroplasty: the CAPAbility, blinded, randomized controlled trial; Lifetime risk of revision and patient factors; Platelet-rich plasma use for hip and knee osteoarthritis in the USA; Where have the knee revisions gone?; Tibial component rotation in total knee arthroplasty: CT-based study of 1,351 tibiae.

The December 2023 Knee Roundup³⁶⁰ looks at: Obesity is associated with greater improvement in patient-reported outcomes following primary total knee arthroplasty; Does mild flexion of the femoral prosthesis in total knee arthroplasty result in better early postoperative outcomes?; Robotic or manual total knee arthroplasty: a randomized controlled trial; Patient-relevant outcomes following first revision total knee arthroplasty, by diagnosis: an analysis of implant survivorship, mortality, serious medical complications, and patient-reported outcome measures using the National Joint Registry data set; Sagittal alignment in total knee arthroplasty: are there any discrepancies between robotic-assisted and manual axis orientation?; Tourniquet use does not impact recovery trajectory in total knee arthroplasty; Impact of proximal tibial varus anatomy on survivorship after medial unicondylar knee arthroplasty; Bone cement directly to the implant in primary total knee arthroplasty?; Maintaining joint line obliquity optimizes outcomes in patients with constitutionally varus knees.

Introduction. Our purpose is to analyze the true costs associated with preoperative CT scans performed for robotic assisted TKA planning and also to determine the value of a formal radiologist reading of these studies. Methods. We reviewed 194 CT scans of 176 sequential patients who underwent primary RTKA by a single surgeon at a suburban teaching hospital. CT radiology reports were reviewed for the presence of incidental findings that might result in change of care to the patient. Actual payments for technical and professional components of the CT scans were retrieved for 170 of the 176 patients. Any patient payments for the CT scan were also recorded. Results. In no CT scan report was there any findings other than arthritis in the knee and nothing was identified that lead to a recommendation for any additional testing. The mean total payment for a preoperative CT scan was $253 (range 0 – 912). The mean technical payment was $206 (range 0 – 856). The mean professional component paid was $48 (range 0 – 66). On average patients personally paid $56 (range 0 – 618). In 99/170 cases (58 %), the patients made no payment. For the remaining 71 patients the mean payment made was $134 (range 10 – 618). Discussion and Conclusion. No CT scan identified any clinical problem other than arthritis – this suggests that the professional component cost of this specific CT scan could be eliminated without harm to patients. The cost of the CT scan – mean <$300 – is low and a minimal part of the total overall cost of a primary TKA. Patients understand the value of the CT scan - preoperative advanced imaging helps ensure a precise and accurate intraoperative experience – and they are willing to pay for any of their costs related to this preoperative test. For figures, tables, or references, please contact authors directly

Summary. The EOS stereography system has been developed for the evaluation of prosthetic alignment. This new low-dose device provides reliable 2D/3D measurements of knee prosthesis alignment. Introduction. Achieving optimal prosthetic alignment during Total Knee Arthroplasty (TKA) is an essential part of the surgical procedure since malpositioning can lead to early loosening of the prosthesis and eventually revision surgery. Conventional weight-bearing radiographs are part of the usual clinical follow-up after both primary TKA and revision TKA (rTKA), to assess alignment in the coronal and sagittal planes. However, proportions and angles may not be correct on radiographs since divergence exists in the vertical and horizontal planes. Furthermore estimating the exact planes by looking at the position of the patella depends on rotation in the hip joint and this may be misinterpreted by the investigator. A computed tomography (CT) scanogram can also be used. However, due to high levels of radiation and costs it is not routinely used. To this end, a new device, the EOS stereography system, has been developed. With this biplanar low-dose X-ray technique, orthogonally made 2D images and 3D reconstructions can be obtained. Advantages of EOS are that images of the leg are obtained on a 1:1 scale with an amount of radiation 800–1000 times lower than CT-scans and 10 times lower than conventional radiographs. Another advantage is that the 3D reconstructions lead to determination of the real coronal and sagittal planes. However, the software for creating 3D reconstructions is developed for the lower limbs without knee prosthesis material. Consequently a reliability study concerning the generation of 2D images and 3D reconstructions of a leg containing a knee prosthesis has not been performed yet. Therefore objective of this study was to investigate interobserver and intraobserver reliability of knee prosthetic alignment measurements after rTKA using EOS. Patients and Methods. Forty anteroposterior and lateral images of 37 rTKA patients were included. Two observers independently performed measurements on these images twice. Measured angles were varus/valgus angle in 2D (VV2D) and 3D (VV3D). Intraclass correlation coefficients (ICCs) were used to determine relative reliability and the Bland and Altman method was used to determine absolute reliability. T-tests were used to test potential differences between the two observers, first and second measurement sessions and 2D and 3D measurements. Results. Relative interobserver reliability was excellent for both VV2D and VV3D with ICCs > 0.95, and no significant differences between the two observers. For the absolute reliability of VV2D, a bias of −0.16° (95%CI: −0.31–0.01) existed between both observers. Absolute reliability of VV3D was good. Relative intraobserver reliability was excellent for both VV2D and VV3D with ICCs > 0.97. No significant difference and no bias between the first and second measurements were found. A significant difference existed between the angles measured in 2D and 3D (p=0.01). Discussion / Conclusion. The EOS low-dose stereography system provides reliable varus/valgus measurements in 2D and 3D for the alignment of the knee joint with a knee prosthesis. However, significant differences exist between the varus/valgus measurements in 2D and in 3D. Therefore, a validation study is suggested to investigate the difference between the 2D measurements and 3D reconstructions and to find a possible explanation for this difference

Aims

Metal allergy in knee arthroplasty patients is a controversial topic. We aimed to conduct a scoping review to clarify the management of metal allergy in primary and revision total knee arthroplasty (TKA).

The October 2023 Knee Roundup³⁶⁰ looks at: Cementless total knee arthroplasty is associated with more revisions within a year; Kinematically and mechanically aligned total knee arthroplasties: long-term follow-up; Aspirin thromboprophylaxis following primary total knee arthroplasty is associated with a lower rate of early periprosthetic joint infection compared with other agents; The impact of a revision arthroplasty network on patient outcomes; Re-revision knee arthroplasty in a tertiary centre: how does infection impact on outcomes?; Does the knee joint have its own microbiome?; Revision knee surgery provision in Scotland; Aspirin is a safe and effective thromboembolic prophylaxis after total knee arthroplasty: a systematic review and meta-analysis; Patellar resurfacing and kneeling ability after total knee arthroplasty: a systematic review.

Abstract

Robotic-assisted total knee arthroplasty (TKA) has proven higher accuracy, fewer alignment outliers, and improved short-term clinical outcomes when compared to conventional TKA. However, evidence of cost-effectiveness and individual superiority of one system over another is the subject of further research. Despite its growing adoption rate, published results are still limited and comparative studies are scarce. This review compares characteristics and performance of five currently available systems, focusing on the information and feedback each system provides to the surgeon, what the systems allow the surgeon to modify during the operation, and how each system then aids execution of the surgical plan.

Cite this article: Bone Jt Open 2023;4(1):13–18.

Purpose: Revision total knee arthroplasty (RTKA) is particularly difficult and results more variable than primary total knee arthroplasty due to the added problem of bone loss. Massive bone allografts have been proposed to restore bone stock and mechanical conditions as close to the physiological situation as possible. The purpose of this retrospective analysis was to assess clinical and radiological results after knee reconstruction with massive allografts in patients undergoing revision total knee arthroplasty. Materials and method: This series included 14 patients who underwent a revision procedure between February 1990 and August 1998 for RTKA with segmentary bone loss and bone defects. This group included seven patients with mechanical failure and seven others with septic loosening. Reconstruction was achieved with a massive allograft sealed around a long stem cemented implant. The composite assembly was impacted into the patient’s bony segment. The allografts were used to reconstruct the distal femur in nine cases, the proximal tibia in one, and both in the others. The IKS score and radiographic homogenisation of the host-graft junction were assessment criteria. Results: Mean follow-up was 50 months (24–110). Mean IKS score was significantly improved from 43 (11–70) pre-operatively to 75 (40–100) at last follow-up (Wilcoxon test, p = 0.002). At last follow-up, the flexion-extension amplitude was 91±10°. Radiographic integration of the allografts was achieved in 14 out of 18 grafts. Three allografts were resorbed leading to fracture with subsequent implant failure and a new revision in two. There were no infections. Discussion and conclusion: Bone grafts may be a solution to the difficult problem of bone loss during RTKA. Massive grafts combined with long stem implants have given encouraging early and mid-term results. The duration of these results is under evaluation

Aims

The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI.

INTRODUCTION. Porous metal bone fillers are frequently used to manage bony defects encountered in revision total knee arthroplasty (rTKA). Compared to structural graft, porous metal bone fillers have shown significantly lower loosening and failure rates potentially due to osseointegration and increased material strength [1]. The strength of porous metal bone fillers used in lower extremities is frequently assessed using compression/shear/torsion test methods, adapted from spine standards. However, these basic methods may lack clinical relevance, and do not provide any insight on the relationship between patient activity and anticipated prosthesis performance. The goal of this study was to evaluate the response of bone fillers under different activities of daily living, in order to define physiologically relevant worst case biomechanics for component evaluation. METHODS. A bone filler tibial augment is shown in Figure 1. A test construct for tibial augments (half-block each for medial and lateral sides) is shown in Figure 2, along with compatible rTKA components. An additional void in the bone was filled using bone cement. Loading was applied through the tibiofemoral contact patches created on polyethylene tibial insert. Loading was used for two activities of daily living; walking and deep knee bend [2–3]. During walking, the tibiofemoral contact patch on the anterior tibial post gets loaded due to femoral hyperextension with 1.2xbody weight (BW), whereas the medial and lateral condyles get loaded with 3xBW compressive load. For deep knee bend, only the condyles get loaded with 4.34xBW. Compared to walking, 45% higher compressive load magnitude in deep knee bend located further posterior was anticipated to create a larger bending moment and induce higher stress on the half augments. A finite element analysis (FEA) was performed by modeling this test construct with a medium size tibial augment. All components were modeled using linear elastic material properties. All interfaces, including the augment-bone interface (representing full bony ingrowth construct) were modeled using bonded contact. The inferior surface of the bone analogue was constrained. Linear static analyses were performed and peak von mises stress predicted in the tibial augments was compared between activities. RESULTS. Deep knee bend resulted in 31% higher stresses in the tibial augments than for walking. High von mises stresses were mostly predicted at the superior/posterior aspect of the internal side of the augment and in the corners of the cutouts. Figure 3 presents the von mises stresses in the tibial augments for both loading scenarios. DISCUSSION. This study revealed that the 45% increased posterior compressive load associated with deep knee bend is a more significant factor than the moment applied to the post during walking gait for a hyperextended knee, when considering the stress in bone filler augments in revision TKA. The stress in the augments can depend on multiple factors and the proposed FEA method can be used to compare stresses in different porous material bone fillers to determine worst case for assessing its strength

Introduction. Extraction of implants due to periprosthetic infection (PJI) following complex revision total knee arthroplasty (rTKA) with extensive hardware can be a daunting undertaking for surgeon and patient alike. We question whether irrigation and debridement (I&D) has a role in this difficult situation with respect to infection control, reoperation, and function. Methods. rTKAs for PJI from 2005–2016 were reviewed. Extensive hardware was defined as: metaphyseal cone/sleeve fixation, distal femoral replacement, periprosthetic fracture hardware, or stems >75mm. Cases were categorized by treatment (I&D or 2-stage exchange). Results. 87 patients were identified with extensive hardware and PJI − 63 I&Ds and 42 2-stages. Follow-up was 3.7 years. Success defined as no re-operation for infection was similar − 38/63 (60.3%) I&D vs 28/42 (66.7%) 2-stage (p=0.54). 26/42 (61.9%) 2-stages required static spacers for post-extraction bone loss or wound problems. Only 14/42 (33%) 2-stages were successfully replanted without re-infection. 11/42 (26.1%) 2-stages had retained spacers while 7/42 (16.7%) 2-stages were eventually fused. In contrast, 38/63 (60.3%) I&Ds maintained original implants without further surgery. 8/63 (12.7%) required repeat I&D; 9/63 (14.3%) underwent eventual 2-stage. Chronic antibiotic suppression was utilized in 53/63 (84.1%) I&Ds and 17/42 (40.5%) 2-stages (p<0.001). Amputation rates were similar − 9/63 (14.3%) I&D vs 7/42 (16.7%) 2-stage (p=0.79). Ambulatory rates were similar − 46/63 (73.0%) I&D vs 24/42 (57.1%) 2-stage (p=0.09). More patients who underwent I&D had a functional TKA at final follow-up (53/63 (84.1%) I&D vs 20/42 (47.6%) 2-stage; p<0.001). Mortality was high − 22/59 (37.3%) I&D vs 13/37 (35.1%) 2-stage (p=1.00). Conclusion. In the setting of PJI following rTKA with extensive hardware, morbidity and mortality is high. I&D with chronic suppression appears as effective as 2-stage procedures in preventing reoperation for infection and maintaining ambulatory status while avoiding the morbidity of 2-stage exchange

Aims

Porous metaphyseal cones can be used for fixation in revision total knee arthroplasty (rTKA) and complex TKAs. This metaphyseal fixation has led to some surgeons using shorter cemented stems instead of diaphyseal engaging cementless stems with a potential benefit of ease of obtaining proper alignment without being beholden to the diaphysis. The purpose of this study was to evaluate short term clinical and radiographic outcomes of a series of TKA cases performed using 3D-printed metaphyseal cones.

INTRODUCTION. The functional and anatomical results of TKA revisions are less good than a primary TKA. The TKA revision frequency increases and we must improve our surgeries and prepare the next standard of these surgeries. The aim of this study was to evaluate the CAOS / one stage strategie to treat the knee PJIs. MATERIALS. In this prospective study, between September 2011 and December 2014, 41 patients treated for chronic knee PJI in a one stage revision. For all of them, an imageless CAOS system (ExactechGPS, Blue- Ortho, Gieres) was used. A personalised profile of revision was created. All surgeries were performed with the same protocole and by using the same Optetrak CC knee components (Exactech, Gainesville, FL). All operations were performed by a single senior surgeon. Indications for the revision TKA were (1) revision of a primary TKA or unicondylar knee arthroplasty (n=27) or (2) revision of revisionTKA (n=15). The measurement of the HKA angle, the Oxford score and the ROM were evaluated pre and post- operatively. RESULTS. 27 males and 14 females with an average age of 71 years old (55–87) were treated for a PIJ (1 unicompartimental prosthesis, 26 TKA and 15 RTKA). The mean follow-up was 41 months (30 months − 6 years). The average time of surgery was 135 mn (120–195) for an average hospitalisation duration of 10 days (7–16). No postoperative outliers were reported (mean preop.: −1,6°+/_−5,1° − Post- op. −0,3°+/_ −1,4°). The average ROM were 115° (90–130°) (Fig. 1). The rate of success for the infection was 92,7%. We report no specific CAS complications and all the navigations were finalised. In this series of complex cases, the rate of infection healing is 92,7%. DISCUSSION. Using CAOS is a safe option with no specific complication. Combined with one stage procedures, it should be an optimal medico-economical strategy for Knee revisions. This first series initiated the « GPS RTKA » project to create a dedicated software evaluated since January 2016 with immediate very good functional results and no complications. For figures and tables, please contact authors directly

Aims

Fungal periprosthetic joint infections (fPJIs) are rare complications, constituting only 1% of all PJIs. Neither a uniform definition for fPJI has been established, nor a standardized treatment regimen. Compared to bacterial PJI, there is little evidence for fPJI in the literature with divergent results. Hence, we implemented a novel treatment algorithm based on three-stage revision arthroplasty, with local and systemic antifungal therapy to optimize treatment for fPJI.

Aims

The use of high tibial osteotomy (HTO) to delay total knee arthroplasty (TKA) in young patients with osteoarthritis (OA) and constitutional deformity remains debated. The aim of this study was to compare the long-term outcomes of TKA after HTO compared to TKA without HTO, using the time from the index OA surgery as reference (HTO for the study group, TKA for the control group).

Introduction. It is well established that diabetic patients undergoing total knee arthroplasty (TKA) are more susceptible to infection, problematic wound healing, and have overall higher complication rates. However there is a paucity in current literature investigating the effects of hypoglycemia on TKA. The purpose of this study was to determine the effect of hypoglycemia on TKA revision (rTKA) incidence analyzing a national private payer database for procedures performed between 2007 and 2015 Q1. Methods. A retrospective review of a national private payer database within the PearlDiver Supercomputer application (Warsaw, IN, USA) for patients undergoing TKA with blood glucose levels ranging from 20 to 219 mg/ml, in increments of 10 mg/ml, was conducted. Patients who underwent TKA were identified by Current Procedural Terminology (CPT)-27447 and International Classification of Disease (ICD) code 81.54. Glucose ranges were identified by filtering for lab identifier values unique to the PearlDiver database. Revision TKA and causes for revision, including mechanical loosening, failure/break, periprosthetic fracture, osteolysis, infection, pain, arthrofibrosis, instability, and trauma) were identified with CPT and ICD-9 Codes. Statistical analysis of this study was primarily descriptive. Results. Our query returned a total of 244,153 TKAs, of which 11,767 (4.8%) were revised. Most TKAs were performed with a glucose range of 70–99 mg/ml (26.3%), followed by 100–109 mg/ml (18.6%). Patients with TKAs performed with a glucose range of 20–29 mg/ml had the highest rate of revision (15.2%) (p<0.001) following the index procedure. Infection was the most common cause of revision among all studied glucose ranges (p<0.001). Conclusion. Infection remains one of the most common causes of rTKA irrespective of glucose level. Our results suggest that hypoglycemia may increase revision rates among TKA patients. Tight glycemic control prior to and during surgery may be warranted

Aims

Orthopaedic infection is a potentially serious complication of elective and emergency trauma and orthopaedic procedures, with a high associated burden of morbidity and cost. Optimization of vitamin D levels has been postulated to be beneficial in the prevention of orthopaedic infection. This study explores the role of vitamin D in orthopaedic infection through a systematic review of available evidence.

Aims

The aim of this study was to determine satisfaction rates after hip and knee arthroplasty in patients who did not respond to postoperative patient-reported outcome measures (PROMs), characteristics of non-responders, and contact preferences to maximize response rates.

Aims

The primary aim of this paper was to outline the processes involved in building the Partners Arthroplasty Registry (PAR), established in April 2016 to capture baseline and outcome data for patients undergoing arthroplasty in a regional healthcare system. A secondary aim was to determine the quality of PAR’s data. A tertiary aim was to report preliminary findings from the registry and contributions to quality improvement initiatives and research up to March 2019.