Patients Receiving a Primary Unicompartmental Knee Replacement Have a Higher Risk of Revision but a Lower Risk of Mortality Than Predicted Had They Received a Total Knee Replacement: Data From the National Joint Registry for England,Wales, Northern Ireland,and the Isle of Man

BackgroundTo determine unicompartmental (UKR) and total knee replacement (TKR) revision rates, compare UKR revision rates with what they would have been had they received TKR instead, and assess subsequent re-revision and 90-day mortality rates.MethodsUsing National Joint Registry data, we estimated UKR and TKR revision and mortality rates. Flexible parametric survival modeling (FPM) was used to model failure in TKR and make estimates for UKR. Kaplan-Meier estimates were used to compare cumulative re-revision for revised UKRs and TKRs.ResultsTen-year UKR revision rates were 2.5 times higher than expected from TKR, equivalent to 70 excess revisions/1000 cases within 10 years (5861 excess revisions in this cohort). Revision rates were 2.5 times higher for the highest quartile volume UKR surgeons compared to the same quartile for TKR and 3.9 times higher for the lowest quartiles respectively. Re-revision rates of revised TKRs (10 years = 17.5%, 95% confidence interval [CI] 16.4-18.7) were similar to revised UKRs (15.2%, 95% CI 13.4-17.1) and higher than revision rates following primary TKR (3.3%, 95% CI 3.1-3.5). Ninety-day mortality rates were lower after UKR compared with TKR (0.08% vs 0.33%) and lower than predicted had UKR patients received a TKR (0.18%), equivalent to 1 fewer death per 1000 cases.ConclusionUKR revision rates were substantially higher than TKR even when demographics and caseload differences were accounted for; however, fewer deaths occur after UKR. This should be considered when forming treatment guidelines and commissioning services. Re-revision rates were similar between revised UKRs and TKRs, but considerably higher than for primary TKR, therefore UKR cannot be considered an intermediate procedure.     

Racial Disparities in Rates of Revision and use of Modern Features in Total Knee Arthroplasty,a National Registry Study

BackgroundThe purpose of our study was to investigate the association of race and ethnicity with rates of modern implant use and postoperative outcomes in total knee arthroplasty (TKA) using the American Academy of Orthopaedic Surgeons American Joint Replacement Registry.MethodsAdult TKAs from 2012 to 2020 were queried from the American Joint Replacement Registry. A total of 1,121,457 patients were available for analysis for surgical features and 1,068,210 patients for analysis of outcomes. Mixed-effects multivariable logistic regression models were used to examine the association of race with each individual surgical feature (unicompartmental knee arthroplasty (UKA) and robotic-assisted TKA (RA-TKA)) and 30- and 90-day readmission. A proportional subdistribution hazard model was used to model the risk of revision TKA.ResultsOn multivariate analyses, compared to White patients, Black (odds ratio (OR): 0.52 P < .0001), Hispanic (OR 0.75 P < .001), and Native American (OR: 0.69 P = .0011) patients had lower rates of UKA, while only Black patients had lower rates of RA-TKA (OR = 0.76 P < .001). White (hazard ratio (HR) = 0.8, P < .001), Asian (HR = 0.51, P < .001), and Hispanic-White (HR = 0.73, P = .001) patients had a lower risk of revision TKA than Black patients. Asian patients had a lower revision risk than White (HR = 0.64, P < .001) and Hispanic-White (HR = 0.69, P = .011) patients. No significant differences existed between groups for 30- or 90-day readmissions.ConclusionBlack, Hispanic, and Native American patients had lower rates of UKA compared to White patients, while Black patients had lower rates of RA-TKA compared to White, Asian, and Hispanic patients. Black patients also had higher rates of revision TKA than other races.     

Does Regional Anesthesia Reduce Complications Following Total Hip and Knee Replacement Compared With General Anesthesia? An Analysis From the National Joint Registry for England,Wales, Northern Ireland and the Isle of Man

BackgroundRegional anesthesia is increasingly used in enhanced recovery programs following total hip replacement (THR) and total knee replacement (TKR). However, debate remains about its potential benefit over general anesthesia given that complications following surgery are rare. We assessed the risk of complications in THR and TKR patients receiving regional anesthesia compared with general anesthesia using the world’s largest joint replacement registry.MethodsWe studied the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man linked to English hospital inpatient episodes for 779,491 patients undergoing THR and TKR. Patients received either regional anesthesia (n = 544,620, 70%) or general anesthesia (n = 234,871, 30%). Outcomes assessed at 90 days included length of stay, readmissions, and complications. Regression models were adjusted for patient and surgical factors to determine the effect of anesthesia on outcomes.ResultsLength of stay was reduced with regional anesthesia compared with general anesthesia (THR = −0.49 days, 95% confidence interval [CI] = −0.51 to −0.47 days, P < .001; TKR = −0.47 days, CI = −0.49 to −0.45 days, P < .001). Regional anesthesia also had a reduced risk of readmission (THR odds ratio [OR] = 0.93, CI = 0.90-0.96; TKA OR = 0.91, CI = 0.89-0.93), any complication (THR OR = 0.88, CI = 0.85-0.91; TKA OR = 0.90, CI = 0.87-0.93), urinary tract infection (THR OR = 0.85, CI = 0.77-0.94; TKR OR = 0.87, CI = 0.79-0.96), and surgical site infection (THR OR = 0.87, CI = 0.80-0.95; TKR OR = 0.84, CI = 0.78-0.89). Anesthesia type did not affect the risk of revision surgery or mortality.ConclusionRegional anesthesia was associated with reduced length of stay, readmissions, and complications following THR and TKR when compared with general anesthesia. We recommend regional anesthesia should be considered the reference standard for patients undergoing THR and TKR.     

The Mid- to Long-Term Outcomes of the Lateral Domed Oxford Unicompartmental Knee Replacement: An Analysis From the National Joint Registry for England,Wales, Northern Ireland,and the Isle of Man

BackgroundLateral unicompartmental knee replacement (UKR) is an alternative to total knee replacement for isolated lateral unicompartmental knee arthritis. The geometry and mechanics of the lateral compartment differ to the medial compartment with the Lateral Domed Oxford UKR designed to address this. We used the National Joint Registry (NJR) data to report the mid- to long-term outcomes of this device.MethodsWe performed a retrospective observational study using NJR data on 992 Lateral Domed Oxford UKRs implanted between 1st January 2005 and 31st December 2017. Outcomes of interest were implant survival and revision indications.ResultsThe 10 year cumulative implant survival rates were 88.6% (CI 85.3-91.2). When compared with <55 year age group, the 55-64, 65-74 and ≥75 groups had significantly lower revision rates (hazard ratio (HR) = 0.56 (CI 0.32-0.98, P = .04), HR 0.40 (CI 0.22-0.72, P = .003), and HR 0.27 (CI 0.12-0.58, P = .001), respectively). The obese group had significantly (P = .04) increased revision risk compared with normal BMI (HR 2.33, CI 1.06-5.12). The commonest reasons for revision surgery were dislocation (n = 23, 2.3%), pain (n = 15, 1.5%), and aseptic loosening (n = 14, 1.4%).ConclusionThe Lateral Domed Oxford UKR provides a good option for isolated lateral compartment osteoarthritis. However, dislocation of the mobile bearing remains a problem, occurring in 2.3% of the patients and accounting for 30% of the revisions. To help prevent dislocation, it is now possible to assess bearing stability intraoperatively and if very unstable to implant a compatible fixed bearing tibial component, without the need for further bone preparation.     

The Impact of Metabolic Syndrome on Reoperations and Complications After Primary Total Hip Arthroplasty

BackgroundMetabolic syndrome (MetS) represents a constellation of interrelated conditions including insulin resistance, abdominal obesity, hypertension, and dyslipidemia. The goals of this study are to determine the impact of MetS on implant survivorship, complications, and clinical outcomes after primary total hip arthroplasty (THA).MethodsUtilizing our institutional total joint registry, 1,268 patients undergoing primary THA were identified with MetS based on the World Health Organization definition and matched 1:1 to those without MetS based on age, gender, and surgical year. MetS patients were further stratified according to the World Health Organization body mass index (BMI) classification to contextualize obesity. Kaplan-Meier analyses were utilized to compare survivorship free of any reoperation, revision, and complications. Clinical outcomes were assessed with Harris hip scores. Mean follow-up after THA was 5 years.ResultsMetS patients had significantly worse 5-year survivorship free from any reoperation compared to those without MetS (93.5% vs 96.1%, respectively; hazard ratio [HR] 1.4, P = .04). When stratifying MetS and BMI classification, the BMI >40 kg/m² had significantly decreased 5-year implant survivorship free from any reoperation (85.9% vs 96.1%, HR 3.4, P < .001), any revision (91.7% vs 97.3%, HR 2.7, P < .001), and reoperation for periprosthetic joint infection (95% vs 99%, HR 5.1, P < .001). Both groups experienced significant and similar improvement in final Harris hip scores (P < .001).ConclusionPatients with MetS had a 1.4-fold increased risk of reoperation after primary THA compared to a matched cohort without the condition. MetS patients with a BMI >40 kg/m² had the highest risk of reoperation, and had a significantly higher revision and periprosthetic joint infection rates, suggesting that morbid obesity remains a critical, independent risk factor beyond MetS.Level of EvidenceLevel 3, Case-control study.     

The Outcome of Total Knee Arthroplasty With and Without Patellar Resurfacing up to 17 Years: A Report From the Australian Orthopaedic Association National Joint Replacement Registry

BackgroundPatellar resurfacing in total knee arthroplasty (TKA) remains a controversial issue after more than 4 decades of TKA. Despite a growing body of evidence from registry data, resurfacing is still based largely on a surgeon’s preference and training. The purpose of this study is to provide long-term outcomes for patellar resurfaced compared to when the patella is not resurfaced.MethodsData from the Australian Orthopaedic Association National Joint Replacement Registry (1999-2017) were used for this study. The analysis included 570,735 primary TKAs undertaken for osteoarthritis. Hazard ratios (HRs) and 17-year cumulative percent revision rates were used to compare revision rates between 4 subgroups: minimally stabilized (MS) patellar resurfacing, posterior stabilized (PS) patellar resurfacing, MS unresurfaced, and PS unresurfaced patella. Additional analyses of the patellar implant type and a comparison of inlay and onlay patellar resurfacing were also performed.ResultsFor all primary TKA, procedures where the patella was not resurfaced have a higher rate of revision compared to procedures where the patella was resurfaced (HR, 1.31; confidence interval, 1.28-1.35; P < .001). Unresurfaced PS knees have the highest cumulative percent revision at 17 years (11.1%), followed by MS unresurfaced (8.8%), PS resurfaced (7.9%), and MS resurfaced (7.1%). Inlay patellar resurfacing has a higher rate of revision compared to onlay patellar resurfacing (HR, 1.27; confidence interval, 1.17-1.37; P < .001).ConclusionResurfacing the patella reduces the rate of revision for both MS and PS knees. MS knees with patellar resurfacing have the lowest rate of revision. Onlay patella designs are associated with a lower revision rate compared to inlay patella designs.     

Periprosthetic Fractures of the Distal Femur: Is Open Reduction and Internal Fixation or Distal Femoral Replacement Superior?

BackgroundThe purpose of this study is to compare open reduction and internal fixation (ORIF) to distal femoral replacement (DFR) for treatment of displaced periprosthetic distal femur fractures.MethodsWe identified 72 patients with minimum 2-year follow-up following a displaced periprosthetic distal femur fracture: 50 were treated with ORIF and 22 with DFR. Outcomes were assessed with multivariate regression analysis and include Knee Society Scores (KSS), infection rates, revision incidence, and mortality.ResultsPatients treated with DFR had a higher Charlson comorbidity index (5.2 vs 3.8; P = .006). The mean postoperative KSS were similar between groups, but the Knee Society Functional Scores were higher in the ORIF group (P = .01). Six ORIF patients (12%) and 3 DFR patients (14%) underwent a revision surgery (P = .1). In the ORIF group, 3 revisions were associated with periprosthetic infection, and 3 revisions occurred for aseptic nonunion. In the DFR group, 1 infection was treated with irrigation and debridement, and 2 cases of patellar maltracking resulted in 1 liner exchange with soft tissue release and 1 femoral revision for malrotation. More patients in the ORIF group required repeat revisions, with twice as many total revisions (P < .001). Six ORIF patients and 7 DFR patients died within 2 years (P = .26).ConclusionThe Knee Society Functional Score favored ORIF, but the total incidence of revision was higher in the ORIF cohort. Given the high mortality and the substantial risk of reoperation in both groups, additional studies are needed regarding the prevention of and optimal treatment for patients with periprosthetic distal femur fractures.     

Synchronous Periprosthetic Joint Infections: High Mortality,Reinfection, and Reoperation

BackgroundSynchronous periprosthetic joint infections (PJIs) are a catastrophic complication with potentially high mortality. We aimed to report mortality, risk of reinfection, revision, reoperation, and implant survivorship after synchronous PJIs.MethodsWe identified 34 patients treated for PJI in more than one joint within a single 90-day period from 1990 to 2018. PJIs involved bilateral knee arthroplasty (27), bilateral hip arthroplasty (4), 1 knee arthroplasty and 1 elbow arthroplasty (1), 1 knee arthroplasty and 1 shoulder arthroplasty (1), and bilateral hip and knee arthroplasty (1). Irrigation and debridement with component retention was performed in 23 patients, implant resection in 10 patients, and a combination of irrigation and debridement with component retention and implant resection in 1 patient. A competing risk model was used to analyze implant survivorship, and Kaplan-Meier survival was used for patient mortality. Mean follow-up was 6 years.ResultsMortality was high at 18% at 30 days and 27% at 1 year. The 1-year cumulative incidence of any reinfection was 13% and 27% at 5 years. The 1-year cumulative incidence of any revision or implant removal was 6% and 20% at 5 years. The 1-year cumulative incidence of unplanned reoperation was 25% and 35% at 5 years. Rheumatoid arthritis was associated with increased risk of mortality (HR 7, P < .01), as was liver disease (HR 4, P = .02).ConclusionIn the largest series to date, patients with synchronous PJIs had a high 30-day mortality rate of 18%, and one-fourth underwent unplanned reoperation within the first year.     

Migration Patterns for Revision Total Knee Arthroplasty in the United States as Reported in the American Joint Replacement Registry

BackgroundRevision total knee arthroplasty (TKA) is associated with a higher complication rate and a greater cost when compared to primary TKA. Based on patient choice, referral, or patient transfers, revision TKAs are often performed in different institutions by different surgeons than the primary TKA. The aim of this study is to evaluate the effect of hospital size, teaching status, and revision indication on the migration patterns of failed primary TKA in patients 65 years of age and older.MethodsAll primary and revision TKAs reported to the American Joint Replacement Registry from January 2012 through March 2020 were included and merged with the Centers for Medicare and Medicaid Services database. Migration was defined as a patient having a primary TKA and revision TKA performed at separate institutions by different surgeons.ResultsIn total, 9167 linked primary and revision TKAs were included in the analysis. Overall migration rates were significantly higher from small (<100 beds; P = .019), non-teaching institutions (P = .002) driven primarily by patients diagnosed with infection. Infection patients had significantly higher migration rates from small (46.8%, P < .001), non-teaching (43.5%, P < .001) institutions, while migration rates for other causes of revision were statistically similar. Most patients migrated to medium or large institutions (84.7%) for revision TKA rather than small institutions (15.3%, P < .001) and to teaching (78.3%) rather than non-teaching institutions (21.7%, P < .001).ConclusionThere is a diagnosis-dependent referral bias that affects the migration rates of infected primary TKA from small non-teaching institutions leading to a flow of more medically complex patients to medium and large teaching institutions for infected revision TKA.     

Staged BiCompartmental Knee Arthroplasty has Greater Functional Improvement,but Equivalent Midterm Survivorship,as Revision TKA for Progressive Osteoarthritis After Partial Knee Arthroplasty

BackgroundProgressive arthritis in the unresurfaced compartments of the knee is one failure mode after partial knee arthroplasty (PKA). While progressive arthritis after PKA is typically treated with revision to TKA (rTKA), staged bicompartmental knee arthroplasty (sBiKA) –the addition of another PKA - is an alternative. This study compared outcomes of sBiKA and rTKA for progressive arthritis after PKA.MethodsA retrospective comparative study of non-consecutive cases at four institutions were performed in patients with an intact PKA, without loosening or wear, who underwent sBiKA (n = 27) or rTKA (n = 30), for progressive osteoarthritis. Outcomes studied were new Knee Society Function and Objective Scores (KSSF, KSSO), KOOS, Jr., ROM, operative times, length of stay, complication rates and the need for reoperations.ResultsMean time to conversion was 7.4 ± 6 years for sBiKA and 9.7 ± 8 for rTKA, P = .178. Patient demographics and pre-operative outcomes were similar among cohorts. At an average of 5.7 ± 3 (sBiKA) and 3.2 ± 2 years (rTKA), KOOS, Jr. significantly improved, P < .001, by an equivalent amount. Post-operative KSSO and KSSF were significantly higher in the sBiKA cohort, respectively, (90.4 ± 10 vs 72.1 ± 20, P < .001) and (80.3 ± 18 vs 67.1 ± 19, P = .011). sBiKA patients had significantly greater improvement in KSSO (30.7 ± 33 vs 5.2 ± 18, P = .003). One sBiKA patient underwent reoperation for continued pain.ConclusionSBiKA has equivalent survivorship, but greater improvement in functional outcomes as rTKA at short to midterm follow-up. Given the shorter operative times and length of stay, sBiKA is a safe and cost-effective alternative to rTKA for progressive osteoarthritis following PKA. Nevertheless, further follow-up is necessary to determine whether sBiKA is a durable option.     

Risk of Prosthetic Joint Infection Increases Following Early Aseptic Revision Surgery of Total Hip and Knee Arthroplasty

BackgroundIt is important to identify risk factors for periprosthetic joint infection (PJI) following total joint arthroplasty in order to mitigate the substantial social and economic burden. The objective of this study is to evaluate early aseptic revision surgery as a potential risk factor for PJI following total hip (THA) and total knee arthroplasty (TKA).MethodsPatients who underwent primary THA or TKA with early aseptic revision were identified in 2 national insurance databases. Control groups of patients who did not undergo revision were identified and matched 10:1 to study patients. Rates of PJI at 1 and 2 years postoperatively following revision surgery were calculated and compared to controls using a logistic regression analysis.ResultsIn total, 328 Medicare and 222 Humana patients undergoing aseptic revision THA within 1 year of index THA were found to have significantly increased risk of PJI at 1 year (5.49% vs 0.91%, odds ratio [OR] 5.61, P < .001 for Medicare; 7.21% vs 0.68%, OR 11.34, P < .001 for Humana) and 2 years (5.79% vs 1.10%, OR 4.79, P < .001 for Medicare; 8.11% vs 1.04%, OR 9.05, P < .001 for Humana). Similarly for TKA, 190 Medicare and 226 Humana patients who underwent aseptic revision TKA within 1 year were found to have significantly higher rates of PJI at 1 year (6.48% vs 1.16%, OR 7.69, P < .001 for Medicare; 6.19% vs 1.28%, OR 4.89, P < .001 for Humana) and 2 years (8.42% vs 1.58%, OR 6.57, P < .001 for Medicare; 7.08% vs 1.50%, OR 4.50, P < .001 for Humana).ConclusionEarly aseptic revision surgery following THA and TKA is associated with significantly increased risks of subsequent PJI within 2 years.     

Despite Improved Survivorship of Uncemented Fixation in Total Knee Arthroplasty for Osteoarthritis,Cemented Fixation Remains the Gold Standard: An Analysis of a National Joint Registry

BackgroundTotal knee arthroplasty (TKA) numbers are increasing worldwide. While cement fixation for both femoral and tibial components is commonly used, alternatives include hybrid and uncemented TKAs. This study aimed to evaluate survivorship, revision rates, and patient-reported outcomes for cemented, hybrid, and uncemented TKAs using New Zealand Joint Registry (NZJR) data.MethodsNZJR data relating to all TKAs performed during the 19 years up to the end of December 2017 were analyzed. Outcomes were assessed using prosthesis survivorship data (including reasons for revision) and Oxford scores at 6 months, 5 years, and 10 years postoperatively.ResultsA total 96,519 primary TKAs were performed during the period examined. Most (91.5%) were fully cemented with 4.8% hybrid and 3.7% uncemented. Mean Oxford scores at 6 months were highest in cemented and lowest in uncemented TKAs (P < .001). However, this was not clinically significant. There was no difference at 5 or 10 years. Ten-year survival rates were 97%, 94.5%, and 95.8% for cemented, uncemented, and hybrid TKAs, respectively. Revision rates were 0.47, 0.74, and 0.52 per 100 component years for cemented, uncemented, and hybrid prostheses, respectively. The revision rate for uncemented prostheses compared with cemented was higher (P < .001). When stratified by age group, there were differences in survival rates between cemented and uncemented groups (P = .001) and hybrid and uncemented groups (P = .038) in patients aged <55 years; between cemented and uncemented groups in those aged 55-64 years (P = .031); and between cemented and hybrid groups in those aged >75 years (P = .004).ConclusionUncemented TKAs had similar patient-reported outcomes but higher revision rates and worse survivorship compared with hybrid or fully cemented TKAs.     

Association of the Intensive Lifestyle Intervention With Total Knee Replacement in the Look AHEAD (Action for Health in Diabetes) Clinical Trial

BackgroundEvidence has established obesity as a risk factor for total knee replacement (TKR) due to osteoarthritis. Obesity is a risk factor for TKR. Randomized trials such as Look AHEAD (Action for Health in Diabetes) have shown long-term successful weight loss with an intensive lifestyle intervention (ILI). It is unknown, however, if intentional weight loss can reduce the risk of TKR.MethodsLook AHEAD randomized persons aged 45-76 with type 2 diabetes who had overweight or obesity to either an ILI to achieve/maintain 7% weight loss or to standard diabetes support and education (DSE). Reported knee pain was assessed using the Visual Analog Scale and Western Ontario McMaster University Osteoarthritis Index questionnaire in 5125 participants without previous TKR. Cox proportional hazard regression was used to model differences in risk of TKR in relation to randomization group assignment (ILI vs DSE) along with baseline body mass index category and baseline knee pain as potential confounders from baseline through Look AHEAD-Extension.ResultsBaseline mean ± SD Western Ontario McMaster University Osteoarthritis Index knee pain scores did not differ by treatment assignment (ILI: 3.6 ± 2.9, DSE: 3.9 ± 3.0, P = .08); as expected due to randomization. During follow up, the 631 (12%) participants who reported having a TKR were more likely to have been heavier (P < .001) and older (P < .001) at enrollment, but risk of TKR did not differ by treatment group assignment (hazard ratio [HR] 1.07, 95% confidence interval [CI] 0.91-1.25, P = .43). Heterogeneity of treatment effect was observed according to baseline knee pain (interaction P = .02). In persons without knee pain at baseline, there was a 29% reduced risk of TKR in ILI compared to DSE (HR 0.71, 95% CI 0.52-0.96). However, in persons with knee pain at baseline, there was no statistically significant association of treatment assignment with respect to subsequent TKR incidence (HR 1.11, 95% CI 0.92-1.33).ConclusionFindings suggest that intensive lifestyle change including physical activity, dietary restriction and behavioral changes to achieve weight loss for prevention of TKR may be most effective in preventing TKR prior to the development of knee pain.     

Contemporary Mortality Rate and Outcomes in Nonagenarians Undergoing Primary Total Hip Arthroplasty

BackgroundNonagenarians (90-99 years) have experienced the fastest percent growth in primary THA utilization recently. However, there are limited data on this population. This study aimed to determine the mortality rate, implant survivorship, clinical outcomes, and complications of primary THAs in nonagenarians.MethodsOur institutional total joint registry was used to identify 144 nonagenarians who underwent 149 primary THAs for osteoarthritis only between 1997 and 2017. The mean age was 92 years, with 63% being female. Mortality, revision, and reoperation were assessed using cumulative incidence with death as a competing risk and Cox regression methods. Clinical outcomes were assessed using Harris hip scores (HHSs). Cemented femoral components were used in 68%. The mean follow-up was 4 years.ResultsThe mortality rates were 6%, 8%, 14%, and 49% at 90 days, 1 year, 2 years, and 5 years, respectively. The 5-year cumulative incidences of any revision and reoperation were 1% and 4%, respectively. The mean HHS improved significantly from 48 preoperatively to 76 at 5 years (P < .001). The 5-year cumulative incidence of any complication was 69%, with the most common being periprosthetic femur fracture (7) intraoperatively, delirium (25) early postoperatively, and periprosthetic femur fracture (10) later postoperatively. Uncemented stem fixation was associated with a higher risk for intraoperative femur fracture (Hazard ratio 5, P = .04) but not with a higher 5-year periprosthetic postoperative femur fracture risk (P = .19).ConclusionNonagenarians undergoing primary THA had substantial mortality rates at 90 days (6%) and 1 year (8%). While the cumulative incidence of any revision and reoperations were low at 5 years, the high complication rate is mostly due to periprosthetic fractures.Level of evidenceLevel IV, retrospective cohort.     

Is Conversion TKA a Primary or Revision? Clinical Course and Complication Risks Approximating Revision TKA Rather Than Primary TKA

BackgroundConversion total knee arthroplasty (convTKA) is associated with increased resource utilization and costs compared with primary TKA. The purpose of this study is to compare 1) surgical time, 2) hospitalization length (LOS), 3) complications, 4) infection, and 5) readmissions in patients undergoing convTKA to both primary TKA and revision TKA patients.MethodsThe American College of Surgeons National Surgical Quality Improvement Project database was queried from 2008 to 2018. Patients undergoing convTKA (n = 1,665, 0.5%) were defined by selecting Current Procedural Terminology codes 27,447 and 20,680. We compared the outcomes of interest to patients undergoing primary TKA (n = 348,624) and to patients undergoing aseptic revision TKA (n = 8213). Univariate and multivariate logistic regression was performed to identify the relative risk of postoperative complications.ResultsCompared with patients undergoing primary TKA, convTKA patients were younger (P < .001), had lower body mass index (P < .001), and were less likely to be American Society of Anesthesiologist class III/IV (P < .001). These patients had significantly longer operative times (122.6 vs 90.3 min, P < .001), increased LOS (P < .001), increased risks for any complication (OR 1.94), surgical site infection (OR 1.84), reoperation (OR 2.18), and readmissions (OR 1.60) after controlling for confounders. Compared with aseptic TKA revisions, operative times were shorter (122.6 vs 148.2 min, P < .001), but LOS (2.91 vs 2.95 days, P = .698) was similar. Furthermore, relative risk for any complication (P = .350), surgical site infection (P = .964), reoperation (P = .296), and readmissions (P = .844) did not differ.ConclusionConversion TKA procedures share more similarities with revision TKA rather than primary TKA procedures. Without a distinct procedural and diagnosis-related group, there are financial disincentives to care for these complex patients.Level of EvidenceII.     

High Mortality After Total Knee Arthroplasty Periprosthetic Joint Infection is Related to Preoperative Morbidity and the Disease Process but Not Treatment

BackgroundPeriprosthetic joint infection (PJI) mortality rate is approximately 20%. The etiology for high mortality remains unknown. The objective of this study was to determine whether mortality was associated with preoperative morbidity (frailty), sequalae of treatment, or the PJI disease process itself.MethodsA multicenter observational study was completed comparing 184 patients treated with septic revision total knee arthroplasty (TKA) to a control group of 38 patients treated with aseptic revision TKA. Primary outcomes included time and the cause of death. Secondary outcomes included preoperative comorbidities and Charlson Comorbidity Index (CCMI) measured preoperatively and at various postoperative timepoints.ResultsThe septic revision TKA cohort experienced earlier mortality compared to the aseptic cohort, with a higher mortality rate at 90 days, 1, 2, and 3 years after index revision surgery (P = .01). There was no significant difference for any single cause of death (P > .05 for each). The mean preoperative CCMI was higher (P = .005) in the septic revision TKA cohort. Both septic and aseptic cohorts experienced a significant increase in CCMI from the preoperative to 3 years postoperative (P < .0001 and P = .002) and time of death (P < .0001 both) timepoints. The septic revision TKA cohort had a higher CCMI 3 years postoperatively (P = .001) and at time of death (P = .046), but not one year postoperatively (P = .119).ConclusionCompared to mortality from aseptic revision surgery, septic revision TKA is associated with earlier mortality, but there is no single specific etiology. As quantified by changes in CCMI, PJI mortality was associated with both frailty and the PJI disease process, but not treatment.     

10-Year Cumulative Incidence and Indications for Revision Total Knee Arthroplasty Among Patients Who Have Sickle Cell Disease

BackgroundLiterature regarding total knee arthroplasty (TKA) outcomes in sickle cell disease (SCD) is limited. Moreover, 10-year survivorship of SCD implants is unknown. This study aimed to observe 10-year cumulative incidence and indications for revision TKA in patients who did and did not have SCD.MethodsPatients who underwent primary TKA were identified using a large national database. The SCD patients were matched by age, sex, and a comorbidity index to a control cohort in a 1:4 ratio. The 10-year cumulative incidence rates were determined using Kaplan–Meier survival analyses. Multivariable analyses were conducted using Cox proportional hazard modeling. Chi-squared analyses were conducted to compare indications for revision between cohorts. In total, 1,010 SCD patients were identified, 100,000 patients included in the unmatched control, and 4,020 patients included in the matched control.ResultsCompared to the unmatched control cohort, SCD patients exhibited higher 10-year all-cause revision (HR: 1.86; P < .001) with higher proportions of revisions for periprosthetic joint infection (PJI) (P < .001), aseptic loosening (P < .001), and hematoma (P < .001). Compared to the matched control, SCD patients had higher 10-year all-cause revision (Hazard Ratio (HR): 1.39; P = .034) with a higher proportion of revisions for PJI (P = .044), aseptic loosening (P = .003), and hematoma (P = .019).ConclusionIndependent of other comorbidities, SCD patients are more likely to undergo revisions for PJI, aseptic loosening, and hematoma compared to patients who do not have SCD. Due to the high-risk of these complications, perioperative and postoperative surgical optimization should be enforced in SCD patients.     

Revision Total Knee Arthroplasty in Young Patients: Higher Early Reoperation and Rerevision

BackgroundRevision total knee arthroplasty (rTKA) rates are increasing in younger patients. Few studies have assessed outcomes of initial aseptic rTKA performed for younger patients compared with traditional-aged patients.MethodsA detailed medical record review was performed to identify patient demographics, medical comorbidities, surgical rTKA indications, timing from index TKA to rTKA, subsequent reoperation rates, component rerevision rates, and salvage procedures for 147 young patients (158 knees) aged 55 years and younger and for a traditional older cohort of 276 patients (300 knees) between 60 and 75 years. Univariate analysis was performed to assess differences in these primary variables, and a log-rank test was used to estimate 5-year implant survival based on either reoperation or component revision and salvage procedures.ResultsYounger TKA patients were more likely to undergo initial aseptic rTKA within 2 years of their primary TKA (52.5% vs 29.0%, P < .001) and were more likely to undergo early reoperation (17.7% vs 9.7%, P = .02) or component rerevision (11.4% vs 6.0%, P < .05) after rTKA. Infection and extensor mechanism complications were more commonly noted in younger patients. Estimated 5-year survival was also lower for both reoperation (59.4% vs 65.7%, P = .02) and component rerevision or salvage (65.8% vs 80.1%, P = .02).ConclusionEarly reoperation and component re-rTKA were performed nearly twice as often in younger rTKA than traditional-aged TKA patients. Care should be given to reduce perioperative infection and extensor mechanism failures after rTKA in younger patients.     

Revision Joint Arthroplasty and Renal Transplant: A Matched Control Cohort Study

BackgroundThere is little literature concerning clinical outcomes following revision joint arthroplasty in solid organ transplant recipients. The aims of this study are to (1) analyze postoperative outcomes and mortality following revision hip and knee arthroplasty in renal transplant recipients (RTRs) compared to non-RTRs and (2) characterize common indications and types of revision procedures among RTRs.MethodsA retrospective Medicare database review identified 1020 RTRs who underwent revision joint arthroplasty (359 revision total knee arthroplasty [TKA] and 661 revision total hip arthroplasty [THA]) from 2005 to 2014. RTRs were compared to their respective matched control groups of nontransplant revision arthroplasty patients for hospital length of stay, readmission, major medical complications, infections, septicemia, and mortality following revision.ResultsRenal transplantation was significantly associated with increased length of stay (6.12 ± 7.86 vs 4.33 ± 4.29, P < .001), septicemia (odds ratio [OR], 2.52; 95% confidence interval [CI], 1.83-3.46; P < .001), and 1-year mortality (OR, 2.71; 95% CI, 1.51-4.53; P < .001) following revision TKA. Among revision THA patients, RTR status was associated with increased hospital readmission (OR, 1.23; 95% CI, 1.03-1.47; P = .023), septicemia (OR, 1.82; 95% CI, 1.41-2.34; P < .001), and 1-year mortality (OR, 2.65; 95% CI, 1.88-3.66; P < .001). The most frequent primary diagnoses associated with revision TKA and THA among RTRs were mechanical complications of prosthetic implant.ConclusionPrior renal transplantation among revision joint arthroplasty patients is associated with increased morbidity and mortality when compared to nontransplant recipients.     

Ten-Year Follow-Up of High-Flexion Versus Conventional Total Knee Arthroplasty: A Matched-Control Study

BackgroundHigh-flexion total knee arthroplasty (HF-TKA) prostheses were designed with hopes of improving knee function. Studies have suggested increased failure with HF-TKAs. The purpose is to compare clinical results of HF-TKA versus conventional TKA (C-TKA) from the same implant system with long-term follow-up.MethodsThis review of prostheses implanted between 2004 and 2007 matched 145 of 179 possible HF-TKAs with 145 of 1347 possible C-TKAs. Mean follow-up was 121.5 ± 20.3 months. We were unable to match 12 HF-TKAs. HF-TKAs with less than 8-year follow-up were excluded. The primary outcome was failure requiring revision. Secondary outcomes included range of motion (ROM), Knee Society Scores (KSS), and radiolucent lines.ResultsIn the matched cohort, there were 15 HF-TKA reoperations, 8 of which involved component revisions. There were 12 reoperations in the C-TKA cohort but no component revisions (P = .001). The analysis of the unmatched cohorts revealed a higher revision rate for HF-TKAs (P = .039) (HF-TKA: 10/179 vs C-TKA: 27/1347). At final follow-up, HF-TKAs exhibited more prosthesis radiolucent lines without evidence of loosening. Particularly, HF-TKAs demonstrated more femoral zone IV radiolucencies (38.7%) at final follow-up compared with C-TKAs (13.8%) (P < .001). There were no differences found between cohorts in ROM or KSS.ConclusionThis study found an increased incidence of failure requiring revision with the HF-TKA in the matched and unmatched analyses. Higher incidences of radiolucent lines were found with HF-TKA. With no observed differences in ROM or KSS and a higher rate of failure with HF-TKA, there appears to be no advantage for use of the HF-TKA.