Abstract. Introduction. Medial fix bearing unicompartmental knee replacement (UKR) designs are consider safe and effective implants with many registries data and big cohort series showing excellent survivorship and clinical outcome comparable to that reported for the most expensive and surgically challenging medial UKR mobile bearing designs. However, whether all polyethylene tibial components (all-poly) provided comparable results to metal-backed modular components during medial fix bearing UKR remains unclear. There have been previous suggestions that all-poly tibia UKR implants might show unacceptable higher rates of early failure due to tibial component early loosening especially in high body max index (BMI) patients. This study aims to find out the short and long-term survival rate of all-poly tibia UKR and its relationship with implant thickness and patient demographics including sex, age, ASA and BMI. Material and Methods. we present the results of a series of 388 medial fixed bearing all-polly tibia UKR done in our institution by a single surgeon between 2007–2019. Results. We found out excellent implant survival with this all-poly tibia UKR design with 5 years survival rate: 96.42%, 7 years survival rate: 95.33%, and 10 years survival rate: 91.87%. Only 1.28% had early revision within 2 years. Conclusion. Fixed bearing medial all-poly tibia UKR shows excellent survivor rate at 2, 5, 7 and 10 years follow up and the survival rate is not related with sex, age, BMI, ASA grade or implant thickness. Contrary to the popular belief, we found out that only 1.71% of all implants was revised due to implant loosening

We report the general mortality rate after total knee replacement and identify independent predictors of survival. We studied 2428 patients: there were 1127 men (46%) and 1301 (54%) women with a mean age of 69.3 years (28 to 94). Patients were allocated a predicted life expectancy based on their age and gender. There were 223 deaths during the study period. This represented an overall survivorship of 99% (95% confidence interval (CI) 98 to 99) at one year, 90% (95% CI 89 to 92) at five years, and 84% (95% CI 82 to 86) at ten years. There was no difference in survival by gender. A greater mortality rate was associated with increasing age (p < 0.001), American Society of Anesthesiologists (ASA) grade (p < 0.001), smoking (p < 0.001), body mass index (BMI) <  20 kg/m. 2. (p < 0.001) and rheumatoid arthritis (p < 0.001). Multivariate modelling confirmed the independent effect of age, ASA grade, BMI, and rheumatoid disease on mortality. Based on the predicted average mortality, 114 patients were predicted to have died, whereas 217 actually died. This resulted in an overall excess standardised mortality ratio of 1.90. Patient mortality after TKR is predicted by their demographics: these could be used to assign an individual mortality risk after surgery

Aims. Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calculate the ‘lifetime risk’ of revision for UKA as a more meaningful estimate of risk projection over a patient’s remaining lifetime, and to compare this to TKA. Methods. Incidence of revision and mortality for all primary UKAs performed from 1999 to 2019 (n = 13,481) was obtained from the New Zealand Joint Registry (NZJR). Lifetime risk of revision was calculated for patients and stratified by age, sex, and American Society of Anesthesiologists (ASA) grade. Results. The lifetime risk of revision was highest in the youngest age group (46 to 50 years; 40.4%) and decreased sequentially to the oldest (86 to 90 years; 3.7%). Across all age groups, lifetime risk of revision was higher for females (ranging from 4.3% to 43.4% vs males 2.9% to 37.4%) and patients with a higher ASA grade (ASA 3 to 4, ranging from 8.8% to 41.2% vs ASA 1 1.8% to 29.8%). The lifetime risk of revision for UKA was double that of TKA across all age groups (ranging from 3.7% to 40.4% for UKA, and 1.6% to 22.4% for TKA). The higher risk of revision in younger patients was associated with aseptic loosening in both sexes and pain in females. Periprosthetic joint infection (PJI) accounted for 4% of all UKA revisions, in contrast with 27% for TKA; the risk of PJI was higher for males than females for both procedures. Conclusion. Lifetime risk of revision may be a more meaningful measure of arthroplasty outcomes than implant survival at defined time periods. This study highlights the higher lifetime risk of UKA revision for younger patients, females, and those with a higher ASA grade, which can aid with patient counselling prior to UKA. Cite this article: Bone Joint J 2022;104-B(6):672–679

Abstract. Background. There is a trend towards minimising length of stay (LOS) after total knee arthroplasty (TKA), as longer LOS is associated with poorer outcomes and higher costs. Patient factors known to influence LOS after TKA include age and ASA grade. Evidence regarding body mass index (BMI) in particular is conflicting. Some studies find that increased BMI predicts greater LOS, while others find no such relationship. Previous studies have generally not examined socioeconomic status, which may be a confounder. They have generally been conducted outside the UK, and prior to the Covid-19 pandemic. Methods. We conducted a retrospective cohort study of 1031 primary TKAs performed 01-04-2021 to 31-12-2021, after resumption of elective surgery in our centre. A multivariate regression analysis was performed using a Poisson model over pre-operative variables (BMI, age, gender, ASA grade, index of multiple deprivation, and living arrangement) and peri-operative variables (AM/PM operation, operation side, duration, and day of the week). Results. Mean LOS was 2.6 days. BMI had no effect on LOS (p > 0.05). Longer LOS was experienced by patients of greater age (p < 0.001), increased ASA grade (p < 0.001), living alone (p < 0.01), PM start time (p < 0.001), and longer operation duration (p < 0.01). Male patients had shorter LOS (p < 0.001). Index of multiple deprivation had no effect (p > 0.05). Conclusion. BMI had no effect on LOS after TKA. Being female and living alone are significant risk factors which should be taken in to account in pre-operative planning

Aims. In the last decade, perioperative advancements have expanded the use of outpatient primary total knee arthroplasty (TKA). Despite this, there remains limited data on expedited discharge after revision TKA. This study compared 30-day readmissions and reoperations in patients undergoing revision TKA with a hospital stay greater or less than 24 hours. The authors hypothesized that expedited discharge in select patients would not be associated with increased 30-day readmissions and reoperations. Methods. Aseptic revision TKAs in the National Surgical Quality Improvement Program database were reviewed from 2013 to 2020. TKAs were stratified by length of hospital stay (greater or less than 24 hours). Patient demographic details, medical comorbidities, American Society of Anesthesiologists (ASA) grade, operating time, components revised, 30-day readmissions, and reoperations were compared. Multivariate analysis evaluated predictors of discharge prior to 24 hours, 30-day readmission, and reoperation. Results. Of 21,610 aseptic revision TKAs evaluated, 530 were discharged within 24 hours. Short-stay patients were younger (63.1 years (49 to 78) vs 65.1 years (18 to 94)), with lower BMI (32.3 kg/m. 2. (17 to 47) vs 33.6 kg/m. 2. (19 to 54) and lower ASA grades. Diabetes, chronic obstructive pulmonary disease, hypertension, and cancer were all associated with a hospital stay over 24 hours. Single component revisions (56.8% (n = 301) vs 32.4% (n = 6,823)), and shorter mean operating time (89.7 minutes (25 to 275) vs 130.2 minutes (30 to 517)) were associated with accelerated discharge. Accelerated discharge was not associated with 30-day readmission and reoperation. Conclusion. Accelerated discharge after revision TKA did not increase short-term complications, readmissions, or reoperations. Further efforts to decrease hospital stays in this setting should be evaluated. Cite this article: Bone Joint J 2022;104-B(12):1323–1328

Aims. The aim of this study was to identify variables associated with time to revision, demographic details associated with revision indication, and type of prosthesis employed, and to describe the survival of hinge knee arthroplasty (HKA) when used for first-time knee revision surgery and factors that were associated with re-revision. Methods. Patient demographic details, BMI, American Society of Anesthesiologists (ASA) grade, indication for revision, surgical approach, surgeon grade, implant type (fixed and rotating), time of revision from primary implantation, and re-revision if undertaken were obtained from the National Joint Registry data for England, Wales, Northern Ireland, and the Isle of Man over an 18-year period (2003 to 2021). Results. There were 3,855 patient episodes analyzed with a median age of 73 years (interquartile range (IQR) 66 to 80), and the majority were female (n = 2,480, 64.3%). The median time to revision from primary knee arthroplasty was 1,219 days (IQR 579 to 2,422). Younger age (p < 0.001), decreasing ASA grade (p < 0.001), and indications for revision of sepsis (p < 0.001), unexplained pain (p < 0.001), non-polyethylene wear (p < 0.001), and malalignment (p < 0.001) were all associated with an earlier time to revision from primary implantation. The median follow-up was 4.56 years (range 0.00 to 17.52), during which there were 410 re-revisions. The overall unadjusted probability of re-revision for all revision HKAs at one, five, and ten years after surgery were 2.7% (95% confidence interval (CI) 2.2 to 3.3), 10.7% (95% CI 9.6 to 11.9), and 16.2% (95% CI 14.5 to 17.9), respectively. Male sex (p < 0.001), younger age (p < 0.001), revision for septic indications (p < 0.001) or implant fracture (p = 0.010), a fixed hinge (p < 0.001), or surgery performed by a non-consultant grade (p = 0.023) were independently associated with an increased risk of re-revision. Conclusion. There were several factors associated with time to first revision. The re-revision rate was 16.2% at ten years; however, the risk factors associated with an increased risk of re-revision could be used to counsel patients regarding their outcome. Cite this article: Bone Joint J 2023;105-B(1):47–55

Aims. Periprosthetic fractures (PPFs) around the knee are challenging injuries. This study aims to describe the characteristics of knee PPFs and the impact of patient demographics, fracture types, and management modalities on in-hospital mortality. Methods. Using a multicentre study design, independent of registry data, we included adult patients sustaining a PPF around a knee arthroplasty between 1 January 2010 and 31 December 2019. Univariate, then multivariable, logistic regression analyses were performed to study the impact of patient, fracture, and treatment on mortality. Results. Out of a total of 1,667 patients in the PPF study database, 420 patients were included. The in-hospital mortality rate was 6.4%. Multivariable analyses suggested that American Society of Anesthesiologists (ASA) grade, history of peripheral vascular disease (PVD), history of rheumatic disease, fracture around a loose implant, and cerebrovascular accident (CVA) during hospital stay were each independently associated with mortality. Each point increase in ASA grade independently correlated with a four-fold greater mortality risk (odds ratio (OR) 4.1 (95% confidence interval (CI) 1.19 to 14.06); p = 0.026). Patients with PVD have a nine-fold increase in mortality risk (OR 9.1 (95% CI 1.25 to 66.47); p = 0.030) and patients with rheumatic disease have a 6.8-fold increase in mortality risk (OR 6.8 (95% CI 1.32 to 34.68); p = 0.022). Patients with a fracture around a loose implant (Unified Classification System (UCS) B2) have a 20-fold increase in mortality, compared to UCS A1 (OR 20.9 (95% CI 1.61 to 271.38); p = 0.020). Mode of management was not a significant predictor of mortality. Patients managed with revision arthroplasty had a significantly longer length of stay (median 16 days; p = 0.029) and higher rates of return to theatre, compared to patients treated nonoperatively or with fixation. Conclusion. The mortality rate in PPFs around the knee is similar to that for native distal femur and neck of femur fragility fractures. Patients with certain modifiable risk factors should be optimized. A national PPF database and standardized management guidelines are currently required to understand these complex injuries and to improve patient outcomes. Cite this article: Bone Joint J 2024;106-B(2):158–165

Aims. The success of total knee arthroplasty (TKA) is usually measured using functional outcome scores and revision-free survivorship. However, reporting the lifetime risk of revision may be more meaningful to patients when gauging risks, especially in younger patients. We aimed to assess the lifetime risk of revision for patients in different age categories at the time of undergoing primary TKA. Methods. The New Zealand Joint Registry database was used to obtain revision rates, mortality, and the indications for revision for all primary TKAs performed during an 18-year period between January 1999 and December 2016. Patients were stratified into age groups at the time of the initial TKA, and the lifetime risk of revision was calculated according to age, sex, and the American Society of Anesthesiologists (ASA) grade. The most common indications for revision were also analyzed for each age group. Results. The overall ten-year survival rate was 95.6%. This was lowest in the youngest age group (between 46 and 50 years) and increased sequentially with increasing age. The lifetime risk of requiring revision was 22.4% in those aged between 46 and 50 years at the time of the initial surgery, and decreased linearly with increasing age to 1.15% in those aged between 90 and 95 years at the time of surgery. Higher ASA grades were associated with increased lifetime risk of revision in all age groups. The three commonest indications for revision were aseptic loosening, infection, and unexplained pain. Young males, aged between 46 and 50 years, had the highest lifetime risk of revision (25.2%). Conclusion. Lifetime risk of revision may be a more meaningful measure of outcome than implant survival at defined time periods when counselling patients prior to TKA. This study highlights the considerably higher lifetime risk of revision surgery for all indications, including infection, in younger male patients. Cite this article: Bone Joint J 2022;104-B(2):235–241

Aims. Periprosthetic joint infection (PJI) occurs in approximately 1% to 2% of total knee arthroplasties (TKA) presenting multiple challenges, such as difficulty in diagnosis, technical complexity, and financial costs. Two-stage exchange is the gold standard for treating PJI but emerging evidence suggests 'two-in-one' single-stage revision as an alternative, delivering comparable outcomes, reduced morbidity, and cost-effectiveness. This study investigates five-year results of modified single-stage revision for treatment of PJI following TKA with bone loss. Methods. Patients were identified from prospective data on all TKA patients with PJI following the primary procedure. Inclusion criteria were: revision for PJI with bone loss requiring reconstruction, and a minimum five years’ follow-up. Patients were followed up for recurrent infection and assessment of function. Tools used to assess function were Oxford Knee Score (OKS) and American Knee Society Score (AKSS). Results. A total of 24 patients were included with a mean age of 72.7 years (SD 7.6), mean BMI of 33.3 kg/m. 2. (SD 5.7), and median ASA grade of 2 (interquartile range 2 to 4). Mean time from primary to revision was 3.0 years (10 months to 8.3 years). At revision, six patients had discharging sinus and three patients had negative cultures from tissue samples or aspirates. Two patients developed recurrence of infection: one was treated successfully with antibiotic suppression and one underwent debridement, antibiotics, and implant retention. Mean AKSS scores at two years showed significant improvement from baseline (27.1 (SD 10.2 ) vs 80.3 (SD 14.8); p < 0.001). There was no significant change in mean AKSS scores between two and five years (80.3 (SD 14.8 ) vs 74.1 (SD 19.8); p = 0.109). Five-year OKS scores were not significantly different compared to two-year scores (36.17 (SD 3.7) vs 33.0 (SD 8.5); p = 0.081). Conclusion. ‘Two-in-one’ single-stage revision is effective for treating PJI following TKA with bone loss, providing patients with sustained improvements in outcomes and infection clearance up to five years post-procedure. Cite this article: Bone Jt Open 2022;3(2):107–113

Abstract. Introduction. Spinal local anaesthesia and opioids have long been used as peri-operative analgesia for patients undergoing arthroplasty procedures. However, intrathecal opioids are associated with numerous complications. ERAS. ®. society guidelines for elective knee replacement (2019) strongly discourage the use of spinal opioids. This study aims to report the impact of low-dose spinal and local infiltrative analgesia on patients undergoing elective knee replacement. Methodology. Retrospective cohort study of patients undergoing knee replacement under the ERAS protocol over 2 years, at a district general hospital under the care of a single surgeon. Results. A total of 80 knee replacements were included in the study (M38:F42, mean age=72.7, mean BMI=31, ASA: 1=8, 2=54, 3=18). 91% received neuroaxial anaesthesia, 89% without intrathecal opioids. Local infiltrative analgesia was used in 99% of patients. The mean length of stay was significantly shorter (2 days), when compared to patients undergoing elective knee replacements without adherence to ERAS. ®. guidance (3.8 days), P<0.001. The average maximum pain score in PACU was 0.8 (0=no pain, 10=maximum pain). All patients were mobilised within 24 hours of surgery. No patients were readmitted within 30 days. 2 patients returned to theatre (retained surgical clip and MUA for stiffness). Conclusions. The implementation of ERAS. ®. guidelines has demonstrated significantly reduced admission days following elective knee arthroplasty. Combined with low complication rates, the reduction in admission days may result in increased hospital bed availability. This has the potential to positively impact elective arthroplasty waiting lists. Further research is underway to evaluate patient-reported outcome measures in this group

Introduction. Hypoalbuminemia has previously been identified as an independent predictor of postoperative complications following total knee arthroplasty (TKA). Given the morbidity and financial burden associated with TKA complications, significant effort has gone into identifying patients at increased risk for perioperative complications. The American Society of Anesthesiologists (ASA) physical status score has been utilized for risk stratification of surgical patients for many years and is a measure of overall health. However, it is unclear how measures like albumin compare to the prognostic ability of this type of global health measure. This study aims to elucidate the utility of preoperative albumin compared with that of the ASA score in predicting complications following TKA. Methods. Patients undergoing TKA between 2005 and 2015 were identified using the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients were stratified based on preoperative hypoalbuminemia (<3.5 g/dL) and ASA score (≤ 2 vs. > 2). Multivariable regression analysis adjusted for age, sex, BMI, and smoking status was utilized to determine predictive potential of hypoalbuminemia and ASA score on each postoperative complication. Results. Of the 79,661 patients included in the cohort, 4.3% had preoperative hypoalbuminemia. Univariate regression analysis found significant predictive abilities of both serum albumin and ASA score on numerous postoperative complications, such as superficial infection, deep infection, MI, pneumonia, renal insufficiency, reintubation, transfusion, readmission, reoperation, and death. Interestingly, multivariable regression analysis demonstrated that hypoalbuminemia more robustly predicted postoperative deep infection than ASA. Discussion and Conclusion. Hypoalbuminemia and ASA each individually predict numerous postoperative complications following TKA. However, this study suggests that while ASA score more accurately predicts post-operative medical complications, hypoalbuminemia may be a more accurate predictor of periprosthetic infection following TKA. Ultimately, preoperative albumin should be incorporated in the pre-operative work-up routine to stratify patient risk, especially regarding postoperative infection

Introduction. The causes of revision total knee replacement are varied. There is a subset of these revision cases (poly wear and some cases of instability for example) where the ability to retain the metal femoral and tibial components and replacing just the polyethylene is an appealing option. We report on a series of RTKR where only the poly insert was replaced and the patients were followed for a minimum of ten years. Materials and Methods. Our study group consisted of 64 consecutive non infected RTKR patients who underwent a revision of the polyethylene alone between 1998 and 2006. All patients had been treated originally with the same cemented, CR, patella resurfaced primary TKR. Reasons for revision were 51 poly wear and/or osteolysis, 7 instability, and 6 other. The average time from the primary to the revision surgery was 9.1 years (range 2.2 to 16.1 years). All patients had an isolated poly liner change. No femurs or tibial trays were revised. Average age of the cohort at revision was 72.2 (range 48 to 88). Average BMI was 31.9 (range 23.6 to 43.9). There were 36 female patients. Of the group, 42 were ASA 1 or 2 and 22 were ASA 3. Pre-op alignment averaged 6.0 (range 2 varus to 8 valgus). Patients were followed for a minimum of 10 years (range 10 to 19 years). Results. At final follow up 13 patients had died, none were lost to follow up leaving 51 patients available for review. There were 7 reoperations in 6 patients (7 knees). Reasons for reoperation were: 4 aseptic tibial loosening at an average of 4.1 years (range 1.2 to 8.3) following first poly revision, two for polywear at an average 9 years post first poly revision, and one for deep infection (5.6 years post first poly revision). Knee society scores at 6 weeks post revision was 93.5 (range 38 to 100) and at final follow up for the non-revised knees was 91.6 (range 36 to 100). Conclusion. In appropriate settings, where the femoral and tibial components are satisfactorily aligned and well fixed and the soft tissues can be balanced, a poly change alone can provide a durable solution for the revision total knee patient. The ability to retain the metal components has advantages in terms of patient morbidity and cost

Introduction. The number of medial unicompartmental knee replacements (UKR) performed for arthritis has increased and as such, revisions to total knee replacement (TKR) is increasing. Previous studies have investigated survivorship of UKR to TKR revision and functional outcomes compared to TKR to TKR revision, but have failed to detail the surgical considerations involved in these revisions. Our objectives are to investigate the detailed surgical considerations involved in UKR to TKR revisions. Methods. This study is a retrospective comparative analysis of a prospectively collected database. From 2005 to 2017, 61 revisions of UKR to TKR were completed at a single center. Our inclusion criteria included: revision of UKR to TKR or TKR to TKR with minimum 1 year follow-up. Our exclusion criteria include: single component and liner revisions and revision for infection. The 61 UKR to TKR revisions were matched 2:1 with respect to age, ASA and BMI to a group of 122 TKR to TKR revisions. The following data was collected: indication for and time to revision, operative skin to skin surgical time, the use of specialized equipment (augment size/location, stem use), intraoperative and postoperative complications, re-operations and outcome scores (WOMAC, Oxford 12, SF 12, satisfaction score). Results. There were no statistical differences between the demographic data from either group (age, BMI, ASA, sex and follow-up range). Progression of arthritis was the most common reason for revision in the UKR to TKR group (30/61, 49%, p < 0.001). Aseptic loosening was the most common reason for revision in the TKR to TKR group (73/122, 60%,) and was encountered more often than aseptic loosening in the UKR to TKR group (21/61, 35%, p=0.002). The operative time was longer in the TKR to TKR group (77 vs 112 min, p< 0.001). Femoral augmentation was required for one 1/61 (1.64%) UNI and 92/122 (75%) TKR revisions, respectively (p <0.001). Medial tibial augments were required in 9/61 (14.8%) of the UKR to TKR group while 12/122 (10%) and 10/122 (8%) of the TKR to TKR group required medial and full tibial augments, respectively (p=0.7). UKR to TKR revisions never required femoral stems while 120/122 (98%) of the TKR to TKR group did (p<0.001). Tibial stems were required in 19/61 (31%) and 122/122 (100%) of UKR to TKR and TKR to TKR groups, respectively (p<0.001). There was no statistical difference in the overall complication rate of either group (15% in the UKR to TKR group and 13% in the TKR to TKR group, p = 0.9). Stiffness was a common complication of UKR to TKR and TKR to TKR re-revisions at 2/61 (3%), and 6/122 (5%), respectively (P = 0.6). Aseptic loosening was also a common complication of in both groups at 2/61 (3%) and 4/122 (3%) in the UKR to TKR and TKR to TKR groups, respectively (p = 0.7). There was no statistical difference in the re-operation rate of either group (10% in the UKR to TKR group and 7% in the TKR to TKR group, P = 1). Stiffness was the most common indication for re-operation in the UKR to TKR group (2/61, 3%, p = 0.11) while aseptic loosening was the most common in the TKR to TKR group (4/122, 3.2%, p = 0.7). The survivorship in the UKR to TKR was 93% and 90% at 5 and 9 years, respectively. The survivorship in the TKR to TKR group was 95% and 94% at 5 and 9 years, respectively, which was not statistically different from the UKR group. Discussion. The most common reason for revision was different between the two groups (p < 0.001) while the skin to skin time was longer in the TKR to TKR group. In terms of revision components, femoral stems were never required in the UKR to TKR group while tibial stems were only required in 31%. Similarly, medial tibial augments were only required in 15% of the UKR to TKR group. While the surgeon must be prepared to use augmentation and stems in UKR to TKR revisions, they can often be completed with primary components and therefor will have an overall lower cost to the health care system. Furthermore, the survivorship and re-operation between the two groups was similar which supports previous literature. The results of this study will allow for a more in-depth cost-effectiveness analysis of UKR to TKR vs TKR to TKR in arthroplasty decision making. Unicompartmental knee replacements should be considered in appropriate patients to decrease the lifetime cost of arthroplasty intervention and potentially decrease the burden on the health care system. For figures, tables, or references, please contact authors directly

Introduction. Hip and knee replacements are being performed at increasing rates and currently account for one of the largest procedure expenditures in the Medicare budget. Outcomes of total knee replacement (TKR) depend on surgeon, patient and implant factors. The impact that the specific implants might have on patient-reported outcomes is unknown. The primary purpose of this study was to evaluate the patient-reported functional outcomes and satisfaction after primary total knee arthroplasty in patients with osteoarthritis who underwent TKR using five different brands of posterior-stabilized implants. Specifically, the aim was to evaluate for any difference in patient-reported outcomes based on implant brand used. The hypothesis was that there would be no difference in functional outcome that could be attributed to the implant used in primary TKR. Methods. Using our institution's total joint arthroplasty registry, we identified 4,135 patients who underwent total knee replacement (TKR) using one of the five most common implant brands used at our institution. These included Biomet Vanguard (N=211 patients), Depuy/Johnson&Johnson Sigma (N=221), Exactech OptetrakLogic (N=1,507), Smith & Nephew Genesis II (N=1,414), and Zimmer NexGen (N=779). Only posterior-stabilized primary TKRs in patients with osteoarthritis were included. Patients were evaluated preoperatively using the Knee Osteoarthritis Outcomes Score (KOOS), Lower Extremity Activity Scale (LEAS), and Short Form-12 (SF-12). Demographics including age, body mass index (BMI), Charleston Comorbidity Index (CCI), ASA physical status classification, sex, and smoking status were collected. Postoperatively, 2-year KOOS, LEAS, SF-12, and satisfaction scores were compared between implant groups. Results. At 2-year follow-up, patient-reported outcome scores were available for a total of 4,069 patients. In multiple regression analysis which separately compared each implant group to the aggregate of all others, after accounting for age, BMI, CCI, ASA status, and sex, there were no clinically significant differences in KOOS score changes from baseline to 2-year follow-up between any of the implants. In 2-year satisfaction, >80% of patients in each implant group were satisfied in all domains measured. In the multivariate regression model, patients in the NexGen group had the highest likelihood of being satisfied (OR 1.63, p=0.006) and OptetrakLogic patients had the lowest likelihood of being satisfied (OR 0.60, P<0.001) although these differences were below the minimal clinically important thresholds. Conclusion. TKR provides patient satisfaction and improvement in function regardless of implant type. While some implant systems had higher outcome scores than others, these differences were all below clinically significant thresholds. Whether these differences are a function of surgeon expertise or implant design is unknown. Future research should focus on identifying specific design elements that contribute to improved patient outcomes. Healthcare administrators may find the similarities in clinical outcomes to be a useful consideration when negotiating implant purchasing contracts

Introduction. A large proportion of patients undergoing total knee arthroplasty (TKA) have severe osteoarthritis in both knees and may consider either simultaneous or staged bilateral TKA. The implications of staged versus simultaneously bilateral TKA for return to work are not well understood. We hypothesized that employed patients who underwent simultaneous bilateral TKA would have significantly fewer days missed from work compared to the sum of days missed from each surgery for patients who underwent staged bilateral TKA. Methods. The prospective arthroplasty registry at Hospital for Special Surgery was utilized. We identified 61 employed patients who had undergone staged bilateral TKA and 152 employed patients who had undergone simultaneous bilateral TKA and had completed the registry's return to work questionnaire. Baseline characteristics and patient reported outcome scores were evaluated. We used a linear regression model, adjusting for potential confounders including age, sex, pre-op BMI, and work type (sedentary, moderate, high activity, or strenuous), to analyze workdays lost after staged versus simultaneous bilateral TKA. Results. Staged patients missed a mean total of 67.9±46.1 days of work across both TKA surgeries, compared to 46.5±29.0 days missed in the simultaneous group (p<0.001). In multivariate mixed regression analysis, adjusted for age, sex, BMI, ASA status, and work type, the staged group missed 16.9±5.7 more days of work compared to the simultaneous group (95%CI 5.8 to 28.1, p=0.003). Compared to sedentary work type, patients with high or strenuous work activity missed 19.4±9.4 (p=0.040) more total work days. Conclusions. Employed patients undergoing simultaneous bilateral TKA missed 17 fewer days of work over the course of their surgical treatment and rehabilitation compared to those undergoing staged bilateral TKA. This information may be useful to surgeons counseling patients with bilateral knee osteoarthritis about staged versus simultaneous bilateral surgery

Background. There are advantages and disadvantages of Unicompartmental (UKR) and Total Knee Replacement, with UKR having better functional outcomes with fewer complications but a higher revision rate. The relative merits depend on patient characteristics. The aim was to compare UKR and TKR risk-benefits and cost-effectiveness in patients with severe systemic morbidity. Methods. Data from the National Joint Registry for England, Wales and Northern Ireland was linked to hospital inpatient and patient-reported outcomes data. Patients with American Society of Anesthesiologists (ASA) grade ≥3 undergoing UKR or TKR were identified. Propensity score stratification was used to compare 90-day complications and 5-year revision and mortality of 2,256 UKR and 57,682 TKR, and in a subset of 145 UKR and 23,344 TKR Oxford Knee Scores (OKS). A health-economic analysis was based on EQ-5D and NHS hospital costs. Results. The OKS was significantly better following UKR than TKR with a difference of 1.83 (95%CI 0.10–3.56). UKR was associated with lower relative risks of venous thromboembolism (0.33, CI0.15–0.74), myocardial infarction (0.73, CI0.36–1.45) and early joint infection (0.85, CI0.33–2.19) but only the decrease in venous thromboembolism was significant. The revision risk following UKR was significantly higher than following TKR (hazard ratio 2.70, CI2.15–3.38) and the mortality was significantly lower (0.52, CI0.36–0.74). At five years the cumulative incidence of revision was 8% higher with UKR, and the cumulative incidence of death was 13% lower. The health economic analysis found that UKR dominated TKR having lower costs (£359, CI340-378) and higher quality-of-life gains (0.33, CI-0.31–0.970). Conclusions. For patients with ASA ≥3, UKR was safer and more cost-effective than TKR. In particular if UKR was used instead of TKR the number of lives saved was higher than the number of extra revisions. UKR should be considered the first option for suitable patients with severe co-morbidity

Introduction. The use of intraoperative liposomal bupivacaine (LB) peri-articular injection has been highly debated for total knee arthroplasty (TKA). We evaluated the effect of an institutional-wide discontinuation of intraoperative LB on immediate postoperative pain scores, opioid consumption, and objective functional outcomes. Material and Methods. Between July 1, 2019 and November 30, 2019, an institutional policy discontinued use of intraoperative LB, while the volume of non-LB with epinephrine was increased from 40-ml to 60-ml. A historical cohort was derived from patients undergoing TKA between January 1, 2019 and June 30, 2019. All patients received the same opioid sparing protocol, minimizing variability in prescribing habits. No adductor canal blocks/pumps were utilized. Nursing documented verbal rating scale (VRS) pain scores were collected from our electronic data warehouse and averaged per patient per 12-hour interval. Opiate administration events were derived as Morphine Milligram Equivalences (MMEs) per patient per 24-hour interval. To assess immediate postoperative functional status, the validated Activity Measure for Post-Acute Care (AM-PAC) tool was utilized. All time events were calculated relative to TKA completion instant. Results. 789 primary TKAs did not receive intraoperative LB, while 888 patients acted as controls. Age was significantly greater in patients that did not receive intraoperative liposomal bupivacaine (66.80±8.97 vs 65.57±9.46; p<.01). Gender, BMI, ASA physical status score, race, smoking status, marital status, surgical time, length of stay and discharge disposition were similar between the two groups (p>.05). Compared to historical controls, discontinuation of LB demonstrated no significant difference in postoperative inpatient VRS pain scores up to 72 hours (p>.05), opioid administration up to 96 hours (p>.05), or AM-PAC scores within the first 24 hours (p>.05). Discussion. Subjective pain scores, opioid consumption, and functional scores were unchanged in the early postoperative period following the discontinuation of intraoperative liposomal delivery of bupivacaine in TKA

PURPOSE OF STUDY. We investigated the effect of weekend knee arthroplasty surgery on length of inpatient stay. METHODS. 341 consecutive patients undergoing primary total knee replacement were retrospectively identified. Of these 62 underwent surgery during the weekend. Length of inpatient stay, age, sex, pre-operative haemoglobin, ASA rating, and day of surgery were recorded. Multiple regression analysis was used to determine the effect of these preoperative factors on length of post-operative inpatient stay. RESULTS. The mean length of stay following primary knee replacement was 5.9 days, with a median 4 days (2-31). Multivariate analysis confirmed that age at operation, sex, pre-operative haemoglobin and ASA were predictive of length of stay following knee arthroplasty. The day of the operation was not predictive of length of post operative stay. DISCUSSION. The results from this study suggest age, sex, ASA and preoperative haemoglobin are predictive of inpatient hospital stay. This is consistent with previous published data. Day of surgery was not predictive of length of stay. Our results suggest that weekend knee arthroplasty surgery does not result in an increased length of inpatient stay

Introduction. Porous metaphyseal cones are increasingly used for fixation in revision total knee arthroplasty (RTKA). Both cemented shorter length stems and longer diaphyseal engaging stems are currently utilized with metaphyseal cones with no clear evidence of superiority. The purpose of this study was to evaluate our experience with 3D printed titanium metaphyseal cones with both short cemented and longer cementless stems from a clinical and radiographic perspective. Methods. In total 136 3D printed titanium metaphyseal cones were implanted. The mean patient age was 63 and 48% were female. The mean BMI was 33 and the mean ASA class was 2.5. There were 42 femoral cones in which 28 cemented and 14 cementless stems were utilized. There were 94 tibial cones in which 67 cemented and 27 cementless stems were utilized. The choice for stem fixation was surgeon dependent and in general cones were utilized for AORI type 2 and 3 bone defects on the femur and tibia. The most common fixation scenario was short cemented stems on both the femur and tibia followed by cemented stem fixation on the tibia and cementless fixation on the femur. Clinical data such as revision, complication, and PRO was collected at last follow-up (minimum follow-up 1 year). Radiographic analysis included cone bony ingrowth and coronal and sagittal alignment on long-standing radiographs. Descriptive statistics were used to compare demographics between patients who had malalignment (HKA beyond +/− 3 degrees and flexion/extension beyond +/− 3 degrees). Adjusted logistic regression models were run to assess malalignment risk by stem type. Results. Patient reported outcomes demonstrated modest improvements with Pre-op KOOS improving from 44 pre-op to 59 post -op and PF-CAT improving from 33 to 37 post-op. PROMIS pain scores decreased significantly from 54 to 44 post-op. 36% of patients had malalignment in either the coronal or sagittal plane. Patients with malalignment were more likely to be female (66.7% vs 40.4%, p-value=0.02). After adjusting for age, sex and BMI, there was a significantly increased risk for coronal plane malalignment when both the femur and tibia had cementless compared to cemented stems (odds ratio=5.54, 95%CI=1.15, 26.80). There was no significantly increased risk when comparing patients with mixed stems to patients with cemented stems. Sagittal plane malalignment was more common with short cemented stems although both coronal plane and sagittal plane malalignment with either stem type was not associated with inferior clinical outcome. Overall cone survivorship was excellent with only two cones removed for infection. Conclusion. Metaphyseal titanium cones provide reliable fixation in revision TKA. However, PROs in this complex patient population show only modest improvement consistent with other variables such as co-morbidities and poor baseline physical function. Small cone inner diameter may adversely influence cementless stem position leading to coronal plane malalignment. Short cemented stems are subject to greater sagittal plane malalignment with no apparent influence on clinical outcome

Aims

In-hospital length of stay (LOS) and discharge dispositions following arthroplasty could act as surrogate measures for improvement in patient pathways, and have major cost saving implications for healthcare providers. With the ever-growing adoption of robotic technology in arthroplasty, it is imperative to evaluate its impact on LOS. The objectives of this study were to compare LOS and discharge dispositions following robotic arm-assisted total knee arthroplasty (RO TKA) and unicompartmental arthroplasty (RO UKA) versus conventional technique (CO TKA and UKA).