Years Of Total Knee Arthroplasty Research Articles

Initiating chemotherapy in joint arthroplasty patients increases the risk of periprosthetic joint infections.

Total Joint Arthroplasties (TJAs) are becoming more popular, resulting in a growing economic burden due to potential postoperative complications, with periprosthetic joint infections (PJIs) playing a significant role. The effect of immunosuppression on PJI risk, particularly in cancer patients following chemotherapy, is unknown. The hypothesis of this study investigated whether chemotherapy increases PJI rates in patients who received post-arthroplasty chemotherapy within one year of surgery. Data from the M161Ortho dataset of PearlDiver patient records database were utilized using ICD-9, ICD-10, and CPT codes. The cohort includes Total Knee Arthroplasty (TKA), Total Hip Arthroplasty (THA), and Total Shoulder Arthroplasty (TSA) patients who underwent post-arthroplasty chemotherapy within one year after surgery between 2010 and 2022. Patients in the matched control group did not receive post-arthroplasty chemotherapy. Pre-arthroplasty chemotherapy recipients, PJI, and post-op first year revisions were excluded. Analyses including the linear logistic regression were performed via R statistical software. Totally, 17,026 patients (8,558 TKAs, 6,707 THAs, and 1,761 TSAs) were included. At two (OR = 1.59, p = 0.034), three (OR = 1.57, p = 0.009), and four (OR = 1.40, p = 0.032) years for TKA, and two (OR = 2.27, p = 0.008), three (OR = 2.32, p < 0.001), and four (OR = 2.25, p0.001) years for THA, PJI rates were significantly higher in the chemotherapy group. TSA patients had a significant rise in PJI after four years (OR = 2.20, p = 0.031). This study reveals a possible relationship between postoperative chemotherapy and an increased incidence of PJI in patients with arthroplasty. Chemotherapy suppresses the immune system, rendering patients more vulnerable to infections. Additional research is required to confirm these findings.

Predictors of Undergoing Revision Within 5 Years of Total Knee Arthroplasty: A Population-Based Study

BackgroundThe objective of this study was to identify the rate and risk factors for revision total knee arthroplasty (TKA) within the first 5 years postoperative. Our secondary objective was to identify the rate of additional surgical procedures and death. MethodsWe conducted a retrospective cohort study among patients in Ontario, Canada who underwent an elective, primary TKA between April 1, 2007, and March 31, 2014, for osteoarthritis. We excluded patients under 40 years and who had undergone a TKA within the previous 15 years. Our final study cohort included 94,193 patients. We reported the proportion of the study cohort who experienced revision surgery within 2 and 5 years of the primary TKA; secondary surgery within 5 years. We conducted Cochran-Armitage tests for trends to assess changes in the proportion of patients who experienced each of the study outcomes, and multivariable logistic regressions to evaluate predictors of a revision TKA. ResultsThere were 3,112 (3.3%) patients who had a revision within 5 years, and 1,866 (2.0%) within 2 years of their primary TKA. 3,316 (3.5%) had a secondary surgery (0.6% patellar resurfacing; 1.6% manipulation; 1.3% synovectomy; 0.5% washout; 0.9% debridement). Lower age, men, lower income, higher comorbidity score, depression, previous arthroscopy, lower surgeon volume, and general anesthesia were all significant positive predictors of revision. ConclusionsIn our study cohort, 2.0% of patients had a revision TKA within 2 years, and 3.3% within 5 years of their primary TKA. Preoperative identification of risk factors may reduce the future prevalence of revision TKAs.

Higher revision rates in patients with preoperative contralateral pes planovalgus deformity following total knee arthroplasty.

The purpose of this study was to compare the incidence of revision in those with pes planovalgus deformity to those without using a large national database. Given the reciprocal changes in lower extremity alignment associated with planovalgus foot deformity, it has been suggested that patients with this deformity has worse outcomes following total knee arthroplasty (TKA). A retrospective cohort analysis of patients undergoing elective TKA was conducted using the PearlDiver database. Patients were stratified into three cohorts: those without pes planovalgus, patients with ipsilateral or bilateral pes planovalgus relative to the TKA, and patients with contralateral pes planovalgus. Patients with prior foot reconstructive surgery were excluded. The cohorts were each matched to those without pes planovalgus. Bivariate analysis was performed comparing 90-day medical complications and 2- and 4-year revisions following TKA. An adjusted number needed to be exposed for one additional person to be harmed (NNEH) was calculated using the adjusted odds ratio (OR) and unexposed event rate. Following matched analysis, those with contralateral pes planovalgus had similar odds (OR 3.41; 95% CI 0.93-12.54; p = n.s.) for aseptic revision within 2 years but significantly higher odds (OR 3.35; 95% CI 1.08-10.41; p = 0.03) within 4 years when compared to those without a pes planovalgus deformity. Within 4 years, there was no significant difference in the incidence of aseptic revision (p = n.s.) in patients with ipsilateral/bilateral pes planovalgus. No patients in any cohort underwent septic revision within 4 years of TKA. This study found that patients with contralateral pes planovalgus deformity had higher odds of aseptic revision within 4 years following primary TKA in a national database, suggesting that the change in gait kinematics associated with this deformity could possibly be associated with increased revision rates. Level III.

Clinical outcomes, complications, and survivorship for unicompartmental knee arthroplasty versus total knee arthroplasty in patients aged 80years and older with isolated medial knee osteoarthritis: a matched cohort analysis.

The primary goal of this study is to compare clinical outcomes, complication rate, and survivorship in octogenarians who underwent total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) by performing a matched cohort analysis. We analyzed 75 medial UKAs performed by a single experienced surgeon. The included cases were matched with 75 TKAs performed during the same study period. Potential TKA matches used identical exclusion criteria. UKAs were age-, gender-, and body mass index (BMI)-matched at the rate of 1 UKA to 1 TKA from our departmental database. Clinical evaluation included the visual analog scale for pain, range of motion (ROM-flexion and extension), Knee Society Score (KSS), and Oxford Knee Score (OKS). Each patient was clinically evaluated on the day before the surgery (T0) and at two follow-ups at least 12months (T1) and 24months (T2) after the surgery. For the survivorship, revision was defined as failure of the implant (periprosthetic joint infection, periprosthetic fracture, or aseptic loosening), and survival was based on implant revision or patient death. Undesirable clinical developments that were not present at baseline or that increased in severity after treatment were classified as adverse events. The mean age at the time of the surgery was 82.1 ± 1.9years for UKA and 81.5 ± 1.8years for TKA (p = 0.06). The two groups differed in regard to surgical time (UKA 44.9 ± 7.2min; TKA 54.4 ± 11.3min; p < 0.001); furthermore, the UKA group showed better function (ROM; flexion and extension) than the TKA group at each follow-up time point (p < 0.05). Both groups reported a significant improvement in all clinical scores (KSS and OKS) when compared with their preoperative status (p < 0.05), while no differences were found between the groups at each follow-up (p > 0.05). The UKA group reported 7 (9.3%) failures, while TKA reported 6 failures. There were no survival differences between the groups (T1: p = 0.2; T2: p = 0.5). Overall complication rate was 6% in the UKA group versus 9.75% in TKA (p = 0.2). The UKA and TKA patients had similar clinical outcomes, post-operative range of motion, and survivorship in octogenarians with medial knee osteoarthritis, with comparable complication rate. Both the surgical procedures may be considered in this patient population, but further long-term follow-up is needed. Level III.

Unicompartmental Knee Arthroplasty Patients Have Lower Joint Awareness and Higher Function at 5 Years Compared to Total Knee Arthroplasties: A Matched Comparison

BackgroundThe purpose of this study was to evaluate postoperative outcomes at minimum 5-year follow-up in patients following unicompartmental knee arthroplasty (UKA) compared to a matched cohort of total knee arthroplasty (TKA) patients. MethodsPatients who had primarily medial compartment osteoarthritis (OA) who met criteria for medial UKA underwent TKA or medial UKA between 2014 and 2015 at a single institution, matched for age, sex, and body mass index. There were 127 UKAs in 120 patients and 118 TKAs in 116 patients included with minimum 5-year follow-up (range, 6 to 8). Mean age was 69 years (range, 59 to 79) and 71 years (range, 62 to 80) in the UKA and TKA groups, respectively (P = .049). ResultsPatients who underwent UKA had significantly higher mean (±SD) Forgotten Joint Scores (87 ± 20 versus 59 ± 34, P < .001); higher Knee Society Scores (88 ± 14 versus 75 ± 21, P < .001); and lower Numeric Pain Rating Scores (0.8 ± 1.6 versus 1.9 ± 2.2, P < .001). Survivorship free from all-cause revision was 96% (95% CI = 93%-99%) and 99% (95% CI = 97%-100%) at 5 years for TKA and UKA, respectively (P = .52). There were 8 both component revisions in the TKA group within 5 years from the date of surgery and 2 UKA conversions to TKA after 5-year follow-up. ConclusionPatients who have medial compartment OA and underwent UKA had significantly lower joint awareness, decreased pain, improved function, and higher satisfaction compared to matched TKA patients at minimum 5-year follow-up while maintaining excellent survivorship.

Temporal Trends in Deep Surgical Site Infections After Six Orthopaedic Procedures Over a 12-year Period Within a US-based Healthcare System.

Centers of excellence and bundled payment models have driven perioperative optimization and surgical site infection (SSI) prevention with decolonization protocols and antibiotic prophylaxis strategies. We sought to evaluate time trends in the incidence of deep SSI and its causative organisms after six orthopaedic procedures in a US-based integrated healthcare system. We conducted a population-level time-trend study using data from Kaiser Permanente's orthopaedic registries. All patients who underwent primary anterior cruciate ligament reconstruction (ACLR), total knee arthroplasty (TKA), elective total hip arthroplasty (THA), hip fracture repair, shoulder arthroplasty, and spine surgery were identified (2009 to 2020). The annual incidence of 90-day deep SSI was identified according to the National Healthcare Safety Network/Centers for Disease Control and Prevention guidelines with manual chart validation for identified infections. Poisson regression was used to evaluate annual trends in SSI incidence with surgical year as the exposure of interest. Annual trends in overall incidence and organism-specific incidence were considered. The final study sample was composed of 465,797 primary orthopaedic procedures. Over the 12-year study period, a decreasing trend in deep SSI was observed for ACLR and hip fracture repair. Although there was variation in incidence rates for specific operative years for TKA, elective THA, shoulder arthroplasty, and spine surgery, no consistent decreasing trends over time were found. Decreasing rates of Staphylococcus aureus infections over time after hip fracture repair, shoulder arthroplasty, and spine surgery and decreasing trends in antibiotic resistance after elective THA and spine surgery were also observed. Increasing trends of polymicrobial infections were observed after TKA and Cutibacterium acnes after elective THA. The overall incidence of deep SSI after six orthopaedic procedures was rare. Decreasing SSI rates were observed for ACLR and hip fracture repair within our US-based healthcare system. Polymicrobial infections after TKA and Cutibacterium acnes after elective THA warrant closer surveillance. IV.

The rate of unnecessary interventions for the management of knee osteoarthritis: a population-based cohort study.

Background:Several commonly used procedures for knee osteoarthritis (OA) are not supported by evidence-based guidelines. The objective of this study was to identify the proportion of patients who underwent knee arthroscopy or magnetic resonance imaging (MRI) and the timing of these procedures before total knee arthroplasty (TKA).Methods:We conducted a retrospective cohort study using administrative data sets from Ontario, Canada. We identified the proportion of patients who underwent knee arthroscopy in the previous 10 years or an MRI in the 3 years before their primary TKA. We also evaluated the rate of arthroscopies by diagnosis. We report the timing of each outcome in relation to the TKA, rates by geographical area, and differences in rates over time.Results:We included 142 275 patients, of whom 36 379 (25.57%) underwent knee arthroscopy (median time 2.8 [interquartile range (IQR) 1.1–6.0] years); 22% of those were within 1 year of TKA and 52% were within 3 years. The rates of arthroscopies for a diagnosis of osteoarthritis (OA) steadily decreased, while those for meniscal-related diagnoses increased over the study period (p < 0.0001). There was significant variation by region. Of the cohort, 23.2% (n = 32 989) had an MRI before their TKA, with rates significantly increasing over time (p < 0.0001).Conclusion:A substantial proportion of patients with knee OA received diagnostic and therapeutic interventions before TKA that are contrary to clinical practice guidelines.

New-Onset Depression After Total Knee Arthroplasty: Consideration of the At-Risk Patient

BackgroundPostoperative new-onset depression (NOD) has gained recent attention as a previously unrecognized complication which may put patients at risk for poor outcomes after elective total hip arthroplasty. We aimed to investigate risk factors for the development of NOD after total knee arthroplasty (TKA) and assess its association with postoperative complications. MethodsThis is a retrospective, population-level investigation of elective TKA patients. Patients with a preoperative diagnosis of depression were excluded from this study. Two groups were compared: patients who were diagnosed with depression within one year after TKA (NOD) and those who did not (control). The association of both preoperative patient factors and postoperative surgical and medical complications with NOD was then determined using multivariate and univariate analyses. ResultsOf 196,728 unique TKA patients in our cohort, 5351 (2.72%) were diagnosed with NOD within one year of TKA. Age <54 year old, female gender, preoperative anxiety disorder, drug, alcohol, and/or tobacco use, multiple comorbidities, and opioid use before TKA were all associated with a diagnosis of NOD postoperatively (all P < .001). Postoperative NOD was associated with periprosthetic fracture (OR 2.11; 95% CI 1.29-3.52; P = .033), aseptic failure (OR 1.61; 95% CI 1.24-2.07; P = .020), prosthetic joint infection (OR 1.55, 95% CI 1.30-1.85; P < .001), stroke (OR 1.24; 95% CI 1.09-1.42; P = .006), and venous thromboembolism (OR 1.24; 95% CI 1.12-1.37; P < .001). ConclusionPost-TKA NOD is common and is associated with poor outcomes. This may aid surgeons in developing both anticipatory measures and institute preventative measures for patients at risk for developing NOD.

Previous History of Knee Arthroscopy in Patients Undergoing Total Knee Arthroplasty: An Examination of the Effect of the Literature and American Academy of Orthopaedic Surgeons 2013 Arthroscopy Guidelines on Clinical Practice

PurposeTo compare the rate of previous knee arthroscopy in patients undergoing total knee arthroplasty (TKA) before (2005-2006) and after (2018) publication of landmark studies that examined the effectiveness of knee arthroscopy as well as the American Academy of Orthopaedic Surgeons 2013 knee arthroscopy guidelines.MethodsWe performed a retrospective chart review of 214 patients who underwent a TKA between 2005 and 2006 (Group 1) and 213 patients who underwent a TKA in 2018 (Group 2). We reviewed medical records to determine whether previous knee arthroscopy was performed. Group comparisons were made using the t test for continuous data and the χ2 test for categorical data, and means ± standard deviation are presented.ResultsPatients in Group 2 were older than those in Group 1 (67.0 ± 8.3 vs 64.3 ± 11.5 years, P = .01); however, there were no differences between groups with respect to sex (P = .40), body mass index (P = .36), and laterality of TKA (P = .05). There was no difference in the history of previous knee arthroscopy between Groups 1 and 2 overall (27% vs 32%, P = .27) and within 10 years of TKA (17% vs 15%, P = .44).ConclusionsWe did not find a difference in the number of previous knee arthroscopies for patients undergoing TKA in 2018 versus 2005-2006. This suggests that the recommendations set forth by landmark clinical trials that examined the effectiveness of knee arthroscopy and the AAOS 2013 knee arthroscopy guidelines did not have a sudden impact within our geographic region, but there is some evidence to suggest a gradual shift in treatment, where knee arthroscopy is withheld near imminent knee arthroplasty.Level of EvidenceIII, retrospective comparative study.

A Team Based Approach is Essential to Optimize Total Knee Arthroplasty Outcomes

Total Knee Arthroplasty (TKA) is the number one, most commonly performed orthopedic operation and remains a reliable, reproducible and cost-effective surgical procedure [1]. There is a high rate of overall patient satisfaction for TKA with a subsequent high demand that continues to rise [1]. Worldwide the average rate of annual Total Knee Arthroplasty (TKA) procedures performed has doubled between 2000 and 2016 [1]. There were approximately 100,000 TKAs respectively performed in the United Kingdom (UK) in 2018 [2]. There were 155,000 Total Knee Arthroplasty’s (TKA) performed in the United States of America (USA) in 2018 with demand projected to increase to reach 1.26 million annual procedures by 2030 in the USA, alone [3,4]. Despite the popularity of this procedure, the average functional improvements following Total Knee Arthroplasty (TKA) are more modest than outcomes after Total Hip Arthroplasty (THA) [1]. The average gain in quality adjusted life years (QALYs) was 3.3 years and 4.3 years for TKA and THA, respectively [1]. These findings may be due to the longer recovery period for Total Knee Arthroplasty (TKA) compared to hip replacements, however it is evident that there may be a role for peri-operative rehabilitation to optimize these outcomes [1].

Administration of Tranexamic Acid Improves Long-Term Outcomes in Total Knee Arthroplasty

BackgroundBlood transfusion in total knee arthroplasty (TKA) is associated with increased morbidity, including periprosthetic joint infection (PJI). Tranexamic acid (TXA) reduces blood transfusion rates, but there is limited evidence demonstrating improved outcomes in TKA resulting from TXA administration. The objectives of this study are determining whether TXA is associated with decreased rate of PJI, decreased rate of outcomes associated with PJI, and whether there are differences in rates of adverse events. MethodsA multicenter cohort study comprising 23,421 TKA compared 4423 patients receiving TXA to 18,998 patients not receiving TXA. Primary outcome was PJI within 2 years of TKA. Secondary outcomes included revision surgery, irrigation and debridement, transfusion, and length of stay. Adverse events included readmission, deep vein thrombosis, pulmonary emboli, myocardial infarction, or stroke. Adjusted odds ratios were determined using linear mixed models controlling for age, sex, thromboembolic prophylaxis, Charlson comorbidity index, year of TKA, and surgeon. ResultsTXA administration reduced incidence of PJI by approximately 50% (odds ratio [OR], 0.55; P = .03). Additionally, there was decreased incidence of revision surgery at 2 years (OR, 0.66; P = .02). Patients receiving TXA had reductions in transfusion rate (OR, 0.15; P < .0001) and length of stay (P < .0001). There was no difference in the rate of pulmonary emboli (OR, 1.20; P = .39), myocardial infarction (OR, 0.78; P = .55), or stroke (OR, 1.17; P = .77). ConclusionAdministration of TXA in TKA resulted in reduced rate of PJI and overall revision surgery. No difference in thromboembolic events were observed. The use of TXA is safe and improves outcomes in TKA. Level of EvidenceLevel III, Observational Cohort Study.

Antibiotic-loaded bone cement is associated with a lower risk of revision following primary cemented total knee arthroplasty: an analysis of 731,214 cases using National Joint Registry data.

Antibiotic-loaded bone cements (ALBCs) may offer early protection against the formation of bacterial biofilm after joint arthroplasty. Use in hip arthroplasty is widely accepted, but there is a lack of evidence in total knee arthroplasty (TKA). The objective of this study was to evaluate the use of ALBC in a large population of TKA patients. Data from the National Joint Registry (NJR) of England and Wales were obtained for all primary cemented TKAs between March 2003 and July 2016. Patient, implant, and surgical variables were analyzed. Cox proportional hazards models were used to assess the influence of ALBC on risk of revision. Body mass index (BMI) data were available in a subset of patients. Of 731 214 TKAs, 15 295 (2.1%) were implanted with plain cement and 715 919 (97.9%) with ALBC. There were 13 391 revisions; 2391 were performed for infection. After adjusting for other variables, ALBC had a significantly lower risk of revision for any cause (hazard ratio (HR) 0.85, 95% confidence interval (CI) 0.77 to 0.93; p < 0.001). ALBC was associated with a lower risk of revision for all aseptic causes (HR 0.85, 95% CI 0.77 to 0.95; p < 0.001) and revisions for infection (HR 0.84, 95% CI 0.67 to 1.01; p = 0.06). The results were similar when BMI was added into the model, and in a subanalysis where surgeons using only ALBC over the entire study period were excluded. Prosthesis survival at ten years for TKAs implanted with ALBC was 96.3% (95% CI 96.3 to 96.4) compared with 95.5% (95% CI 95.0 to 95.9) in those implanted with plain cement. On a population level, where 100 000 TKAs are performed annually, this difference represents 870 fewer revisions at ten years in the ALBC group. After adjusting for a range of variables, ALBC was associated with a significantly lower risk of revision in this registry-based study of an entire nation of primary cemented knee arthroplasties. Using ALBC does not appear to increase midterm implant failure rates. Cite this article: Bone Joint J 2019;101-B:1331-1347.

Prior Knee Arthroscopy Is Associated With Increased Risk of Revision After Total Knee Arthroplasty

BackgroundKnee arthroscopy (KA) is frequently performed to provide improved joint function and pain relief. However, outcomes following total knee arthroplasty (TKA) after prior KA are not fully understood. The purpose of this study is to determine the relationship between prior KA within 2 years of TKA on revision rates after TKA. MethodsData were collected from the Humana insurance database using the PearlDiver Patient Records Database from 2006 to 2017. Subjects were identified using Current Procedural Terminology and International Classification of Diseases procedure codes to identify primary TKA. Patients were stratified into 2 groups based upon a history of prior KA. Univariate and multivariate analyses were conducted to determine association between KA and outcomes at 2-year postoperative period. ResultsIn total, 138,019 patients were included in this study, with 3357 (2.4%) patients receiving a KA before TKA and 134,662 (97.6%) patients who did not. The most common reason for KA was osteoarthritis (40.0%), followed by medial tear of the meniscus (26.0%) and chondromalacia (21%.0). After adjustment, prior KA was associated with increased revision rate (odds ratio [OR], 1.392; P = .003), postoperative stiffness (OR, 1.251; P = .012), periprosthetic joint infection (OR, 1.326; P < .001), and aseptic loosening (OR, 1.401; P = .048). ConclusionPrior KA is significantly associated with increased 2-year TKA revision rate. The most common etiology for arthroscopy was osteoarthritis. The results of the study, showing that arthroscopy before TKA substantially increases the rates of revision, PJI, aseptic loosening, and stiffness, lend further credence to the idea that patients may be better served by nonsurgical management of their degenerative pathology until they become candidates for TKA. Subjecting this population to arthroscopy appears to offer limited benefit at the cost of poorer outcomes when they require arthroplasty in the future. Level of EvidenceLevel III therapeutic study.

50 years of total knee arthroplasty

50 years of total knee arthroplasty

Systemic Lupus Erythematosus Does Not Increase Risk of Adverse Events in the First 6 Months After Total Knee Arthroplasty.

Increasing numbers of patients with systemic lupus erythematosus (SLE) are undergoing total knee arthroplasty (TKA). Whether postsurgical adverse events (AEs) are higher in patients with SLE than patients with osteoarthritis (OA) is unknown. This study aims to compare AEs within 6 months of TKA. Patients in a single institution's arthroplasty and SLE registries who underwent TKA from 2007 to 2014 were eligible. SLE cases were matched 1:2 to OA on age, sex, year of TKA, and procedure type. AEs were collected through chart review and registry responses. Baseline characteristics were compared and regression analysis performed to determine predictors of AEs. Fifty-two SLE TKA were matched to 104 OA TKA. There was no difference in follow-up between groups. SLE patients had more comorbidities (≥1 Charlson-Deyo comorbidity: SLE 38.4% vs. OA 17.3%; P-value < 0.001) and steroid use (preoperative [SLE 28.8% vs. OA 1.9%, P-value < 0.001] and perioperative "stress-dose" [30.8% vs. 2.9%, P-value = 0.01]). SLE patients did not experience more major (SLE 25.0% vs. OA 19.2%; P-value = 0.41), minor (15.4% vs. 10.6%; P-value = 0.39), or total (38.5% vs. 27.9%; P-value = 0.18) AEs. AEs were not increased among patients on stress-dose steroids. In a multiple logistic regression analysis controlling for comorbidities and diagnosis, neither SLE (OR 1.61, 95% CI 0.74-3.50) nor >1 comorbidity (OR 1.05, 95% CI 0.46-2.39) was an independent risk factor for AEs. SLE is not an independent risk factor for increased AEs 6 months after TKA. Stress-dose steroid use does not heighten AE risk. These findings should inform recommendations for SLE patients considering TKA.

Risk of Post-TKA Acute Myocardial Infarction in Patients With a History of Myocardial Infarction or Coronary Stent.

Acute myocardial infarction (AMI) is one of the most important perioperative complications of total knee arthroplasty (TKA). Although risk-stratification tools exist for the prediction of cardiac complications including AMI after noncardiac surgery, such stratification does not differentiate the patients with a coronary stent alone, AMI without a stent, or AMI with a stent. The risk of postoperative AMI in these patient groups may vary. Several studies have recommended suitable times for noncardiac surgery in patients with a coronary stent; however, they do not differentiate between the patients with AMI and no AMI. The suitable time of noncardiac surgery for patients with AMI and stent may vary from those with a stent alone. Moreover, a study to evaluate the risk of AMI within 1 year in an Asian population with a history of AMI or coronary stent who underwent TKA has not been reported. (1) What are the risks of AMI within 1 year of TKA in patients who have had a stent alone, AMI without a stent, or AMI with a stent as compared with patients without an AMI/stent? (2) For patients with AMI/stent placement, when can TKA be performed where the risk of subsequent AMI normalizes? (3) What comorbidities are associated with post-TKA AMI? (4) Is the risk of AMI within 1 year after surgery in patients undergoing TKA without a history of AMI/stent higher than that in patients with no surgery? This study is a retrospective study of the medical claim records of 128,216 patients who underwent TKA between 1997 and 2010 in Taiwan. The records were retrieved from the research database of the Bureau of National Health Insurance in Taiwan, which maintains the records of 99.68% of the Taiwan population. The patients who had a history of AMI or coronary stent placement within the year before TKA were compared with the patients who had not experienced AMI or stent placement before TKA. The control subjects were matched according to sex, age, Charlson score, and year of surgery. There were 2413 patients in each group. The patients with a history of AMI or stent placement and the timing of TKA after coronary event were further stratified as with a coronary stent alone, AMI without a stent, and AMI with a stent. The effects of the comorbidities of renal failure, diabetes, liver failure, and hypertension were also analyzed individually. The risk of AMI within 1 year after TKA was investigated using bivariate analysis and the Cox proportional hazard model. To compare the risk of AMI within 1 year of surgery in the patients with a history of TKA and no AMI/stent with the population without a history of surgery, a similar bivariate analysis and the Cox proportional hazard model were applied to their matched case and control groups, each containing 110,980 patients. In the adjusted model, using no AMI/stent before TKA as a reference, patients having undergone AMI + stent had the highest risk (hazard ratio [HR], 5.23; 95% confidence interval [CI], 1.81-15.14; p = 0.002), AMI alone without a stent had less risk (HR, 4.88; 95% CI, 1.49-16.01; p = 0.009), and stent alone with AMI had the lowest risk (HR, 3.16; 95% CI, 1.29-7.71; p = 0.012). In all patients, risk of AMI after TKA was not different than reference values after 1 year of initial AMI or stent (stent: HR, 1.67; 95% CI, 0.71-3.94; p = 0.239; AMI: HR, 1.88; 95% CI, 0.42-8.49; p = 0.412; AMI + stent: HR, 1.91; 95% CI, 0.53-6.89; p = 0.321). The risk of post-TKA AMI was elevated within 1 year of the previous episode of AMI/stent (0-180 days: HR, 8.42; 95% CI, 3.03-23.41; p < 0.001; 181-365 days: HR, 7.52; 95% CI, 2.47-22.88; p < 0.001). Only chronic renal failure under hemodialysis was associated with increased risk of AMI within 1 year of TKA (adjusted HR, 4.34; 95% CI, 1.22-15.43; p = 0.023). Patients undergoing TKA with no history of AMI/stent had a lower risk of AMI within 1 year of TKA compared with the patients with no history of surgery (adjusted HR, 0.92; 95% CI, 0.86-0.99; p = 0.016). This study found the risk of post-TKA AMI remains high within 1 year in patients with a history of AMI/stent. It is recommended that an elective TKA should be performed at least 1 year after an episode of AMI or stent placement. Stents do not provide protection against post-TKA AMI within 6 months of the AMI and patients with AMI + stent have a higher risk of AMI than those with only AMI. Patients of AMI/stent on hemodialysis have a very high risk of post-TKA AMI. However, the risk of AMI is lower in post-TKA patients compared with those with no TKA. Level III, prognostic study.

Bone Mineral Density Changes in the Hip and Spine of Men and Women 1-Year After Primary Cemented Total Knee Arthroplasty: Prospective Cohort Study

This study evaluated age- and sex-adjusted changes in total hip and spine bone mineral density (BMD) within 1year of total knee arthroplasty (TKA) using a prospective, longitudinal cohort with a one-year follow-up. Preoperatively, subjects underwent routine bone mineral densitometry of their hip and spine, which was repeated 12months postoperatively. Of 108 subjects, 97 (90%) completed BMD testing. Total hip BMD decreased significantly over time (1.80% change, P<0.001) with females losing more than males (P<0.001). The pattern was similar, but attenuated in the spine. Subjects undergoing primary cemented TKA had significant bone loss in the hip within 12months, beyond that expected with age.

LETTER TO THE EDITOR Revision of Unicondylar to Total Knee Arthoplasty: A Systematic Review

To assess revision rates after knee arthroplasty we compared cumulative results from world wide clinical studies and arthroplasty registers from the 1960 up to now in one of the largest reviews ever [1]. We found, the overall revision rate at ten years was 6% for total knee arthroplasty (TKA) and17%for unicondylar protheses (UKA). Literature from non-register studies are biased regarding UKA [2]. After the first revision, the five year revision rate was 3% for TKR and 9% for UKR [3]. Therefore, it can be calculated that revision rate after 15 years for TKA is 9% (6% + 3%) and rate for UKR is 26% (17%+9%). We therefore compared two treatments options with a different outcome.

CORR Insights®: Risk Factors for Revision Within 10 Years of Total Knee Arthroplasty

CORR Insights®: Risk Factors for Revision Within 10 Years of Total Knee Arthroplasty

Increased Risk of Complications Following Total Joint Arthroplasty in Patients With Rheumatoid Arthritis

Most of the evidence regarding complications following total hip arthroplasty (THA) and total knee arthroplasty (TKA) are based on patients with osteoarthritis (OA); less is known about outcomes in rheumatoid arthritis (RA). Using a validated algorithm for identifying patients with RA, we undertook this study to compare the rates of complications among THA and TKA recipients between those with RA and those without RA. In patients who underwent a first primary elective THA or TKA between 2002 and 2009, those with RA were identified using a validated algorithm: a hospitalization with a diagnosis code for RA or 3 physician billing claims with a diagnosis code for RA, with at least 1 claim by a specialist (rheumatologist, orthopedic surgeon, or internist) in a 2-year period. Recipients with diagnostic codes suggesting an inflammatory arthritis, but not meeting RA criteria, were classified as having inflammatory arthritis. All remaining patients were deemed to have OA. Cox proportional hazards models, censored on death, were used to determine the relationship between the type of arthritis and the occurrence of specific complications, adjusting for potential confounders (age, sex, comorbidity, and provider volume). We identified 43,997 eligible THA recipients (3% with RA) and 71,793 eligible TKA recipients (4% with RA). Total joint arthroplasty recipients with RA had higher age and sex-standardized rates of dislocation following THA (2.45%, compared with 1.21% for recipients with OA) and higher age and sex-standardized rates of infection following TKA (1.26%, compared with 0.84% for recipients with OA). Controlling for potential confounders, recipients with RA remained at increased risk of dislocation within 2 years of THA (adjusted hazard ratio [HR] 1.91, P = 0.001) and remained at increased risk of infection within 2 years of TKA (adjusted HR 1.47, P = 0.03) relative to recipients with OA. Patients with RA are at higher risk of dislocation following THA and are at higher risk of infection following TKA relative to those with OA. Further research is warranted to elucidate explanations for these findings, including the roles of medication profile, implant choice, postoperative antibiotic protocol, and method of rehabilitation following joint replacement.