Open Access Publication in Total Knee Arthroplasty Is Associated With Increased Social Media Attention, but Is Not Associated With Increased Citations.

BACKGROUND: Open access (OA) publication is growing in total joint arthroplasty literature. While OA manuscripts are free to view, these publications require a fee from authors. This study aimed to compare social media attention and citation rates between OA and non-OA publications in the total knee arthroplasty (TKA) literature. METHODS: There were 9,606 publications included, with 4,669 (48.61%) as OA articles. The TKA articles were identified from 2016 to 2022. Articles were grouped as OA or non-OA and Altmetric Attention Score (AAS), a weighted count of social media attention, and the Mendeley readership were analyzed using negative binomial regressions while adjusting for days since publication. RESULTS: The OA articles had greater mean AAS (13.45 versus 8.42, P = .012) and Mendeley readership (43.91 versus 36.72, P < .001). OA was not an independent predictor of number of citations when compared to non-OA articles (13.98 versus 13.63, P = .914). Subgroup analysis of studies in the top 10 arthroplasty journals showed OA was not an independent predictor of AAS (13.51 versus 9.53, P = .084) or number of citations (19.51 versus 18.74, P = .495) but was an independent predictor of Mendeley readership (49.05 versus 40.25, P < .003). CONCLUSION: The OA publications in the TKA literature were associated with increased social media attention, but not overall citations. This association was not observed among the top 10 journals. Authors may use these results to weigh the relative importance of readership, citations, and online engagement to the cost of OA publication.

Over the Past Decade, Preoperative Anemia Has Become a Greater Predictor of Transfusions After Total Knee Arthroplasty.

BACKGROUND: With advancements in perioperative blood management and the use of tranexamic acid, the rate of transfusions after total knee arthroplasty (TKA) has substantially decreased. As these principles are refined, other modifiable risk factors, such as preoperative anemia, may play an increasingly important role in transfusion risk for patients undergoing TKA. METHODS: A multicenter, national database was utilized to identify patients undergoing TKA from 2010 to 2021. Anemia was defined by World Health Organization definitions as < 12 g/dL for women and < 13 g/dL for men. A predictive model was created using backwards elimination logistic regression to predict transfusion risk, controlling for demographic and medical covariates. The coefficient of anemia was then analyzed for each year. The trend over time was fitted with a best-fit linear regression equation. RESULTS: There were 509,117 patients who underwent TKA, and had a mean age of 67 years (range, 18 to 89). There were 57,716 (11%) patients who were anemic preoperatively, and 15,426 (3%) of patients required a transfusion. Rate of transfusion decreased from 10.6% in 2010 to 0.6% in 2021. The odds ratio associated with anemia as a predictor of transfusion increased from 3.1 (95% confidence interval: 2.1 to 4.6) in 2010 to 14.0 (95% confidence interval: 8.9 to 24) in 2021. CONCLUSIONS: The results of this study demonstrate that the importance of preoperative anemia as a predictor of transfusion has increased over the past decade as rates of transfusion have decreased. As perioperative blood management protocols improve, preoperative anemia should be considered an important focus of intervention to reduce the risk of transfusion prior to TKA. LEVEL OF EVIDENCE: III.

Publishing on Topical Subjects in Total Joint Arthroplasty Is Associated With Increased Social Media Attention.

BACKGROUND: Social media platforms are often used for research dissemination and collaboration. Given the increased prevalence of online-only publications, understanding what drives research dissemination is important. Here, we analyzed factors associated with increased social media attention among peer-reviewed publications in total knee arthroplasty, total hip arthroplasty, and unicompartmental knee arthroplasty. METHODS: We analyzed publications about total knee arthroplasty, total hip arthroplasty, or unicompartmental knee arthroplasty from 2010 to 2022 using a national database. We analyzed a weighted count of social media mentions, using negative binomial regressions adjusting for days since publication. Publications on "hot topics" in arthroplasty were examined including navigation/robotics, COVID-19, race/ethnicity, body mass index, and reimbursement. There were 9,542 publications included, 4,216 (44%) were open access (OA), 338 (3.5%) included navigation, 32 (0.34%) discussed race/ethnicity, 20 (0.2%) discussed COVID-19, 3,840 (40%) were randomized studies, 30 (0.3%) discussed reimbursement, and 2,867 (30%) were in top-10 orthopaedic journals. RESULTS: Factors associated with higher weighted score included studies about COVID-19 (50 versus 6.0, P < .001), race/ethnicity (15.8 versus 6.0, P < .001), OA status (6.3 versus 5.8, P = .001), and randomized studies (6.5 versus 5.7, P < .001). Studies from top-10 journals had a lower score (5.8 versus 6.2, P = .025), as did studies about body mass index (3.4 versus 6.1, P = .001). Studies about navigation and reimbursement did not have significantly different scores. CONCLUSIONS: Studies on COVID-19, race/ethnicity, randomized studies, and OA publication were associated with increased social media while those in top-10 orthopaedic journals had lower scores. LEVEL OF EVIDENCE: Level IV, Prognostic Study.

Osteoporosis and Total Knee Arthroplasty: Higher 5-Year Implant-Related Complications.

BACKGROUND: The risk of revision surgery in patients who have osteoporosis after total knee arthroplasty (TKA) is understudied. Our aim was to compare the 5-year cumulative risk of revision surgery after TKA in patients who have preoperative osteoporosis. METHODS: A national administrative claims database was queried for patients undergoing primary TKA from 2010 to 2021. There were 418,054 patients included, and 41,760 (10%) had osteoporosis. The 5-year incidence of revision surgery was examined for all-causes, periprosthetic fracture (PPF), aseptic loosening, and periprosthetic joint infection (PJI). A multivariable analysis was conducted using Cox proportional hazards models. Hazards ratios (HRs) were reported with 95% confidence intervals (CIs). RESULTS: The 5-year rate of all-cause revision surgery was higher for patients who had osteoporosis (HR 1.1, 95% CI: 1.0 to 1.2), however, the highest risk of revision surgery was seen for PPF (HR 1.8, 95% CI: 1.6 to 2.1). Patients who had osteoporosis also had elevated risk of revision surgery for PJI (HR 1.2, 95% CI: 1.1 to 1.3) and aseptic loosening (HR 1.2, 95% CI: 1.1 to 1.3). Osteoporosis was independently associated with PJI and aseptic loosening at a higher rate in obese patients. CONCLUSIONS: In unadjusted survival analysis, those who had osteoporosis have a marginally lower risk of all-cause revision surgery. However, after controlling for age, sex and comorbidities, patients who had osteoporosis have a nearly 2-fold increased risk of 5-year revision for PPF after TKA, and mildly increased risk of revision for all causes, aseptic loosening, and PJI. Obesity may also modulate this association. Future studies should determine the extent to which treatment of osteoporosis modifies these postoperative outcomes.

Risk Factors Associated With Quadriceps Tendon Extensor Mechanism Disruption Following Total Knee Arthroplasty.

BACKGROUND: Quadriceps tendon extensor mechanism disruption is an infrequent but devastating complication after total knee arthroplasty (TKA). Our knowledge of specific risk factors for this complication is limited by the current literature. Thus, this study aimed to identify potential risk factors for quadriceps tendon extensor mechanism disruption following TKA. METHODS: A retrospective cohort analysis was performed using the PearlDiver Administrative Claims Database. Patients undergoing TKA without a prior history of quadriceps tendon extensor mechanism disruption were identified. Quadriceps tendon extensor mechanism disruption included rupture of the quadriceps tendon, patellar tendon, or fracture of the patella. Patients who had a minimum of 5 years of follow-up after TKA were included. A total of 126,819 patients were included. Among them, 517 cases of quadriceps tendon extensor mechanism disruption occurred (incidence 0.41%). Hypothesized risk factors were compared between those who had postoperative quadriceps tendon extensor mechanism disruption and those who did not. RESULTS: On multivariate analysis, increased Charlson Comorbidity Index (odds ratio (OR): 1.10, 95% confidence interval (CI) [1.07 to 1.13]; P < .001), obesity (OR: 1.49, 95% CI [1.24 to 1.79]; P < .001), and fluoroquinolone use any time after TKA (OR: 1.24, 95% CI [1.01 to 1.52]; P = .036) were significantly associated with quadriceps tendon extensor mechanism disruption. CONCLUSIONS: Our study identified the incidence of quadriceps tendon extensor mechanism disruption following TKA as 0.41%. Identified risk factors for quadriceps tendon extensor mechanism disruption after TKA include an increased Charlson Comorbidity Index, obesity, and use of fluoroquinolones postoperatively.

Can You Pay Your Way to Readership? Free to Publish Open Access Formats Receive Greater Readership and Citations Than Paid Open Access Formats in Total Knee Arthroplasty Literature.

BACKGROUND: As publishing with open access is becoming increasingly popular within orthopaedics, understanding the types of publishing options available and what each may deliver is critically important. Hybrid articles require a high article processing charge. Open journal articles have a lower fee, while closed license articles are freely accessible at no charge. Open repository articles are peer-reviewed manuscripts posted freely online. The purpose of this study was to determine the relationship between article type and resulting citations, social media attention, and readership in total knee arthroplasty (TKA) literature. METHODS: Open access TKA journal articles published since 2016 were found using the Altmetric Explorer Database. Data gathered included the Altmetric Attention Score (attention), Mendeley Readership Score (readership), and citations per article. Articles were grouped by type: open journal, hybrid, closed license, and open repository. Results were analyzed using descriptive statistics and Tukey's analysis; α = 0.05. RESULTS: A total of 9,606 publications were included. The open repository had the greatest mean citations (14.40), while open journal (9.55) had fewer than all other categories (P < .001). Hybrid had the greatest mean attention (10.35), and open journal (6.16) had a lower mean attention than all other categories (P ≤ .002). Open repository had the greatest mean readership (44.68), and open journal (34.00) had a lower mean readership than all other categories (P ≤ .012). The mean publication fee for paid publication options was $1,792 United States dollars. CONCLUSIONS: In open access TKA literature, free-to-publish open repositories had the greatest mean citations and readership. Free publication options, open repositories and closed licenses, had greater readership compared to paid publication options.

Osteoporotic Patients Undergoing Total Hip Arthroplasty Have a Similar 5-Year Cumulative Incidence Rate of Periprosthetic Fracture Regardless of Cemented Versus Cementless Femoral Stem Fixation.

BACKGROUND: In osteoporotic patients, surgeons may utilize cemented femoral fixation to minimize risk of fracture. The purpose of this study was to compare 5-year implant survivability in patients who have osteoporosis who underwent elective total hip arthroplasty (THA) with cementless versus cemented fixation. METHODS: A retrospective analysis of patients who have osteoporosis undergoing THA with either cemented or cementless femoral fixation was conducted using a national administrative claims database. Of the 18,431 identified THA patients who have osteoporosis, 15,867 (86.1%) underwent cementless fixation. The primary outcome was a comparison of the 5-year cumulative incidences of aseptic revision, mechanical loosening, and periprosthetic fracture (PPF). Kaplan-Meier and Multivariable Cox Proportional Hazard Ratio analyses were used, controlling for femoral fixation method, age, sex, a comorbidity scale, use of osteoporosis medication, and important comorbidity. RESULTS: There was no difference in aseptic revision (Hazard's Ratio (HR): 1.13; 95% Confidence Interval (CI): 0.79 to 1.62; P value: .500) and PPF (HR: 0.96; 95% CI: 0.64 to 1.44; P value: .858) within 5 years of THA between fixation cohorts. However, patients who had cemented fixation were more likely to suffer mechanical loosening with 5 years post-THA (HR: 1.79; 95% CI: 1.17 to 2.71; P-value: .007). CONCLUSIONS: We found a similar 5-year rate of PPF when comparing patients who underwent cementless versus cemented femoral fixation for elective THA regardless of preoperative diagnosis of osteoporosis. While existing registry data support the use of cemented fixation in elderly patients, a more thorough understanding of the interplay between age, osteoporosis, and implant design is needed to delineate in whom cemented fixation is most warranted for PPF prevention.

The Definition of Anemia Matters When Using Preoperative Hemoglobin as a Screening Tool Prior to Total Hip and Knee Arthroplasty.

BACKGROUND: Preoperative anemia is common in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). Several definitions of anemia have been described, with no clear consensus on the optimal one for preoperative screening. We hypothesized that depending on the definition used preoperatively, the proportion of anemic patients identified who would require a postoperative allogeneic blood transfusion would vary significantly. METHODS: A total of 681,141 patients were identified in a national database who underwent either THA or TKA. Preoperative anemia was classified according to the World Health Organization (WHO) definition, Cleveland Clinic (CC) definition, or race, age, and sex-specific definition described by Beutler et al in 2006. The optimal preoperative (OP) hemoglobin thresholds to predict perioperative transfusions were also calculated using receiver operating characteristic curves. RESULTS: When using the WHO definition, 18% of anemic patients required a transfusion versus 14% (OP definition), 12% (CC definition), and 16% (Beutler definition). Similarly, 0.69% of anemic patients sustained a periprosthetic joint infection within 30 days using the WHO definition versus 0.59% (OP definition), 0.60% (CC definition), or 0.66% (Beutler definition). Using the WHO definition, 5.3% of patients would have sustained a major complication versus 4.5% (OP definition), 4.4% (CC definition), and 5.0% (Beutler definition). CONCLUSIONS: Variation in the definition of anemia for preoperative screening in THA and TKA results in substantial differences in discriminative ability to predict perioperative transfusions. The WHO definition identified the largest proportion of patients who ultimately received a perioperative transfusion.

The Creation of Data-Driven Preoperative Hemoglobin A1c and Same-Day Glucose Strata to Stratify Complication Risk Following Total Hip Arthroplasty.

BACKGROUND: This study identifies data-driven strata for preoperative Hemoglobin A1c (HbA1c) and same-day glucose levels that maximize differences in the likelihood of complications following total hip arthroplasty (THA). METHODS: Patients who underwent THA from 2013 to 2022 were identified using a national database. In total, 18,728 patients were identified with a mean age of 67 years (range, 18 to 80). Stratum specific likelihood ratio (SSLR) analysis determined separate strata for HbA1c and same-day glucose levels that minimized the likelihood of 90-day complications following THA. Each stratum was propensity-score matched based on age, sex, hypertension, heart failure, chronic obstructive pulmonary disease, and obesity to the lowest respective stratum. The risk ratio (RR) with respect to the lowest matched stratum was observed. RESULTS: Our SSLR analysis identified 3 data-driven HbA1c strata (4.5 to 5.9, 6.0 to 6.9, and 7.0+) and two same-day glucose strata (60 to 189 and 190+) that predicted 90-day major complications. For HbA1c, when compared to the lowest strata (4.5 to 5.9), the risk of 90-day major complications sequentially increased as the HbA1c strata increased: 6.0 to 6.9 (RR: 1.21; P = .041), 7+ (RR: 1.82; P < .001). For same-day glucose, when compared to the matched lowest strata (60 to 189), the risk of 90-day major complications was higher for the 190+ strata (RR: 1.5; P < .001). CONCLUSIONS: Our results support the use of multiple HbA1c strata that can be incorporated into preoperative risk-stratification models. Additionally, we identified a single cut-off level of 190 as a maximum target blood glucose level perioperatively.

Trends in Extended Oral Antibiotic Prophylaxis Utilization Following Primary and Revision Total Hip Arthroplasty From 2010 to 2022.

BACKGROUND: In patients considered high-risk for infection, extended oral antibiotic (EOA) prophylaxis has been demonstrated to reduce rates of prosthetic joint infection following total hip arthroplasty (THA). Although national guidelines regarding their use have not yet been created, the increase in literature surrounding EOA prophylaxis suggests a potential change in practice patterns. The purpose of this study was to investigate the trends in utilization of EOA prophylaxis following THA from 2010 to 2022 and identify prescription patterns. METHODS: A total of 646,059 primary THA and 51,879 aseptic revision THA patients were included in this study. Patients who underwent primary or aseptic revision THA between 2010 and 2022 were identified in a national administrative claims database. Rates and duration of EOA prescriptions were calculated. A secondary analysis examined rates of utilization across demographics, including patients considered high risk for infection. RESULTS: From 2010 to 2022, utilization of EOA increased by 366% and 298% following primary and revision THA, respectively. Of patients prescribed postoperative antibiotics, 30% and 59% were prescribed antibiotics for more than 7 days following primary and revision THA, respectively. Rates of utilization were similar between high-risk individuals and the general population. CONCLUSIONS: Rates of utilization of EOA prophylaxis after THA have increased significantly since 2010. As current trends demonstrate a wide variation in prescription patterns, including in length of antibiotic duration and in patient population prescribed, guidelines surrounding the use of EOA prophylaxis after THA are necessary to promote antibiotic stewardship while preventing rates of periprosthetic joint infection.

10-Year Cumulative Incidence and Indications for Revision Total Joint Arthroplasty for Patients Who Have Ehlers-Danlos syndrome.

BACKGROUND: Long-term complications following total joint arthroplasty are not well established for patients who have Ehlers-Danlos syndrome (EDS), a group of connective tissue disorders. This study compared 10-year incidence of revision surgery after total hip arthroplasty (THA) and total knee arthroplasty (TKA) in patients who have and do not have EDS. METHODS: A retrospective cohort analysis was conducted using a national all-payer claims database from 2010 to 2021 to identify patients who underwent primary TKA or THA. Patients who had and did not have EDS were propensity-score matched by age, sex, and a comorbidity index. Kaplan-Meier analyses and Cox proportional hazard models were utilized to determine the cumulative incidence and risks of revision experienced by patients who have and do not have EDS. RESULTS: The EDS patients who underwent TKA had a higher risk of all-cause revision (hazard ratio (HR): 1.50, 95% confidence interval (95% CI): 1.09 to 2.07, P < 0.014) and risk of revision due to instability (HR = 2.49, 95% CI: 1.37 to 4.52, P < 0.003). The EDS patients who underwent THA had a higher risk of all-cause revision (HR = 2.32, 95% CI: 1.47 to 3.65, P < 0.001), revision due to instability (HR = 4.26, 95% CI: 2.17 to 8.36, P < 0.001), and mechanical loosening (HR = 3.63, 95% CI: 2.05 to 6.44, P < 0.001). CONCLUSION: Patients who had EDS were found to have a higher incidence of revision within 10 years of undergoing TKA and THA compared to matched controls, especially for instability. Patients who have EDS should be counseled accordingly. Surgical technique and implant selection should include consideration for increased constraint in TKA and larger femoral heads or dual mobility articulations for THA.

The Association Between Oral Bone Mineral Density-Reducing Medications and the Risk of 2-Year Implant-Related Complications Following Total Knee Arthroplasty.

BACKGROUND: Certain medications interfere with the bone remodeling process and may potentially increase the risk of complications after total knee arthroplasty (TKA). As patients undergoing TKA may be taking these bone mineral density (BMD)-reducing medications, it is unclear as to whether and which medications impact TKA outcomes. Therefore, the purpose of this study was to observe the impact of various BMD-reducing medications on 2-year implant-related complications following TKA. METHODS: A retrospective analysis of patients undergoing primary TKA was conducted using a national administrative claims database. Patients were identified if they were taking any known BMD-reducing medication and were compared to control patients. To control for confounders associated with taking multiple agents, multivariable logistic regression analyses were conducted for each 2-year outcome (all-cause revision, loosening-indicated revision, and periprosthetic fracture--indicated revision), with the output recorded as odds ratios (ORs). RESULTS: In our study, 502,927 of 1,276,209 TKA patients (39.4%) were taking at least one BMD-reducing medication perioperatively. On multivariable analysis, medications associated with a higher likelihood of 2-year all-cause revision included first- and second-generation antipsychotics (SGAs) (OR: 1.42 and 1.26, respectively), selective serotonin reuptake inhibitors (SSRIs) (OR: 1.14), glucocorticoids (1.13), and proton pump inhibitors (PPIs) (OR: 1.23) (P < .05 for all). Medications associated with a higher likelihood of 2-year periprosthetic fracture included SGAs (OR: 1.51), SSRIs (OR: 1.27), aromatase inhibitors (OR: 1.29), and PPIs (OR: 1.42) (P < .05 for all). CONCLUSIONS: Of the drug classes observed, the utilization of perioperative PPIs, SSRIs, glucocorticoids, first-generation antipsychotics, and SGAs was associated with the highest odds of all-cause revision. Our findings suggest a relationship between these medications and BMD-related complications; however, further studies should seek to determine the causality of these relationships.

Can Hip and Knee Arthroplasty Surgeons Help Address the Osteoporosis Epidemic?

BACKGROUND: Osteoporosis is a known, modifiable risk factor for lower extremity periprosthetic fractures. Unfortunately, a high percentage of patients at risk of osteoporosis who undergo THA or TKA do not receive routine screening and treatment for osteoporosis, but there is insufficient information determining the proportion of patients undergoing THA and TKA who should be screened and their implant-related complications. QUESTIONS/PURPOSES: (1) What proportion of patients in a large database who underwent THA or TKA met the criteria for osteoporosis screening? (2) What proportion of these patients received a dual-energy x-ray absorptiometry (DEXA) study before arthroplasty? (3) What was the 5-year cumulative incidence of fragility fracture or periprosthetic fracture after arthroplasty of those at high risk compared with those at low risk of osteoporosis? METHODS: Between January 2010 and October 2021, 710,097 and 1,353,218 patients who underwent THA and TKA, respectively, were captured in the Mariner dataset of the PearlDiver database. We used this dataset because it longitudinally tracks patients across a variety of insurance providers throughout the United States to provide generalizable data. Patients at least 50 years old with at least 2 years of follow-up were included, and patients with a diagnosis of malignancy and fracture-indicated total joint arthroplasty were excluded. Based on this initial criterion, 60% (425,005) of THAs and 66% (897,664) of TKAs were eligible. A further 11% (44,739) of THAs and 11% (102,463) of TKAs were excluded because of a prior diagnosis of or treatment for osteoporosis, leaving 54% (380,266) of THAs and 59% (795,201) of TKAs for analysis. Patients at high risk of osteoporosis were filtered using demographic and comorbidity information provided by the database and defined by national guidelines. The proportion of patients at high risk of osteoporosis who underwent osteoporosis screening via DEXA scan within 3 years was observed, and the 5-year cumulative incidence of periprosthetic fractures and fragility fracture was compared between the high-risk and low-risk cohorts. RESULTS: In total, 53% (201,450) and 55% (439,982) of patients who underwent THA and TKA, respectively, were considered at high risk of osteoporosis. Of these patients, 12% (24,898 of 201,450) and 13% (57,022 of 439,982) of patients who underwent THA and TKA, respectively, received a preoperative DEXA scan. Within 5 years, patients at high risk of osteoporosis undergoing THA and TKA had a higher cumulative incidence of fragility fractures (THA: HR 2.1 [95% CI 1.9 to 2.2]; TKA: HR 1.8 [95% CI 1.7 to 1.9]) and periprosthetic fractures (THA: HR 1.7 [95% CI 1.5 to 1.8]; TKA: HR 1.6 [95% CI 1.4 to 1.7]) than those at low risk (p < 0.001 for all). CONCLUSION: We attribute the higher rates of fragility and periprosthetic fractures in those at high risk compared with those at low risk to an occult diagnosis of osteoporosis. Hip and knee arthroplasty surgeons can help reduce the incidence and burden of these osteoporosis-related complications by initiating screening and subsequently referring patients to bone health specialists for treatment. Future studies might investigate the proportion of osteoporosis in patients at high risk of having the condition, develop and evaluate practical bone health screening and treatment algorithms for hip and knee arthroplasty surgeons, and observe the cost-effectiveness of implementing these algorithms. LEVEL OF EVIDENCE: Level III, therapeutic study.

Delay of Timing of Anterior Cruciate Ligament Reconstruction Is Associated With Lower Risk of Arthrofibrosis Requiring Intervention.

PURPOSE: To conduct 2 separate stratum-specific likelihood ratio analyses in patients younger than 40 year of age (<40 years) and those aged 40 and older (40+ years) at time of anterior cruciate ligament (ACL) reconstruction to define data-driven strata between ACL tear and primary isolated ACL reconstruction in which the risk of arthrofibrosis, using manipulation under anesthesia and arthroscopic lysis of adhesions as surrogates, is significantly different. METHODS: A retrospective cohort analysis was conducted using the PearlDiver Database. Patients who underwent ACL reconstruction were identified using the Current Procedure Terminology code 29888. Patients were stratified to those aged younger than 40 (<40) and those 40 and older (40+) at time of ACL reconstruction. The incidence of 2-year arthrofibrosis was calculated for weekly intervals from initial ACL injury to reconstruction. Stratum specific likelihood ratio analysis was conducted to determine data-driven intervals from initial ACL tear to reconstruction that optimize differences in 2-year arthrofibrosis. Following the identification of these intervals for both those <40 and 40+, multivariable analysis was conducted. RESULTS: For those <40, stratum-specific likelihood ratio analysis identified only 2 data-driven timing strata: 0-5 and 6-26 weeks. For those 40+, stratum-specific likelihood ratio analysis also only identified 2 data-driven strata: 0-9 and 10-26 weeks. A delay in ACL reconstruction from initial injury by at least 6 weeks in patients younger than 40 and at least 10 weeks in patients older than 40 years is associated with a 65% and 35% reduction of 2-year manipulation under anesthesia and arthroscopic lysis of adhesions, respectively. CONCLUSIONS: Our analysis showed a delay in ACLR of at least 6 weeks in patients younger than 40 years to be associated with a 65% reduction in the risk of surgical intervention for arthrofibrosis and a delay of at least 10 weeks in patients 40 years and older to be associated with only a 35% reduction in the risk of surgical intervention for arthrofibrosis. The authors propose this difference in reduction to be multifactorial and potentially associated with mechanism of injury, activity level, and preoperative factors such as amount of physical therapy, rather than solely timing. LEVEL OF EVIDENCE: Level III, retrospective comparative prognostic study.

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

PURPOSE: 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). METHODS: 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. RESULTS: 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. CONCLUSION: 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 OF EVIDENCE: Level III.

A Novel Method for Stratification of 30-Day Major Complication Risk Using Body Mass Index Thresholds for Patients Undergoing Total Knee Arthroplasty: A National Cohort of 443,157 Patients.

BACKGROUND: Many organizations have used pre-established body mass index (BMI) cut-offs to guide surgical decision-making. As there have been many improvements in patient optimization, surgical technique, and perioperative care over time, it is important to reassess these thresholds and contextualize them to total knee arthroplasty (TKA). The purpose of this study was to calculate data-driven BMI thresholds that predict significant differences in risk of 30-day major complications following TKA. METHODS: Patients who underwent primary TKA from 2010 to 2020 were identified in a national database. Stratum-specific likelihood ratio (SSLR) methodology was used to determine data-driven BMI thresholds at which the risk of 30-day major complications increased significantly. These BMI thresholds were tested using multivariable logistic regression analyses. A total of 443,157 patients were included, who had a mean age of 67 years (range, 18 to 89 years), mean BMI of 33 (range 19 to 59), and 11,766 (2.7%) patients had a 30-day major complication. RESULTS: SSLR analysis identified four BMI thresholds that were associated with significant differences in 30-day major complications: 19 to 33, 34 to 38, 39 to 50, and 51+. When compared to those who had a BMI between 19 and 33, the odds of sustaining a major complication sequentially and significantly increased by 1.1, 1.3, and 2.1 times (P < .05 for all) for the other thresholds. CONCLUSION: This study identified four data-driven BMI strata using SSLR analysis that were associated with significant differences in the risk of 30-day major complications following TKA. These strata can be used to guide shared decision-making in patients undergoing TKA.

Preoperative Anemia is an Independent Risk Factor for Increased Complications and Mortalities After Total Knee Arthroplasty Regardless of Postoperative Transfusions.

BACKGROUND: Preoperative anemia is associated with adverse events following total knee arthroplasty (TKA). It remains unknown if this effect is due to comorbid conditions, adverse events associated with transfusions, or the anemia itself. We used propensity-score matching to isolate the effect of anemia on postoperative complications following TKA, regardless of blood transfusions. METHODS: Patients undergoing primary TKA from 2010 to 2020 without receiving a perioperative blood transfusion, were identified using a large national database. A 1:1 propensity score matching was used to create cohorts of anemic and nonanemic patients matched on Charlson Comorbidity Index (CCI), American Society of Anesthesiology (ASA) classification, age, sex, and prevalence of bleeding disorders. There were 43,370 patients were included in each group (mean age 68 [range, 29 to 99; 44% male]). The 1:1 matching yielded groups with similar CCI, ASA classification, age, sex, and prevalence of bleeding disorders (all, P > .9). RESULTS: Anemic patients had a higher incidence of major complications (4.1 versus 2.8%; P < .001), 30-day mortality rate (0.2 versus 0.1%; P < .001), and extended lengths of stay (LOS) (8.3 versus 6.6%; P < .001). Anemic patients also had increased 30-day rates of wound infection requiring hospital admission, renal failure, reintubation, myocardial infarction, and pneumonia (all, P < .001). CONCLUSION: In matched cohorts of anemic versus nonanemic patients undergoing TKA, all who had no postoperative blood transfusion, anemic patients had higher rates of complications, extended LOS, and mortalities. Thus, anemia should be considered an independent risk factor for complications following TKA.

Body Mass Index and Revision Total Knee Arthroplasty: Does Cause for Revision Vary by Underweight or Obese Status?

BACKGROUND: Body mass index (BMI) impacts risk for revision total knee arthroplasty (rTKA), but the relationship between BMI and cause for revision remains unclear. We hypothesized that patients in different BMI classes would have disparate risk for causes of rTKA. METHODS: There were 171,856 patients who underwent rTKA from 2006 to 2020 from a national database. Patients were classified as underweight (BMI < 19), normal-weight, overweight/obese (BMI 25 to 39.9), or morbidly obese (BMI > 40). Multivariable logistic regressions adjusted for age, sex, race/ethnicity, socioeconomic status, payer status, hospital geographic setting, and comorbidities were used to examine the effect of BMI on risk for different rTKA causes. RESULTS: Compared to normal-weight controls, underweight patients were 62% less likely to undergo revision due to aseptic loosening, 40% less likely due to mechanical complications, 187% more likely due to periprosthetic fracture, 135% more likely due to periprosthetic joint infection (PJI). Overweight/obese patients were 25% more likely to undergo revision due to aseptic loosening, 9% more likely due to mechanical complications, 17% less likely due to periprosthetic fracture, and 24% less likely due to PJI. Morbidly obese patients were 20% more likely to undergo revision due to aseptic loosening, 5% more likely due to mechanical complications, and 6% less likely due to PJI. CONCLUSION: Mechanical reasons were more likely to be the cause of rTKA in overweight/obese and morbidly obese patients, compared to underweight patients, for whom revision was more likely to be infection or fracture related. Increased awareness of these differences may promote patient-specific management to reduce complications. LEVEL OF EVIDENCE: III.

Interval Time of at Least 6 Weeks Between Bilateral Total Knee Arthroplasties is Associated With Decreased Postoperative Complications.

BACKGROUND: Staged, bilateral total knee arthroplasty (TKA) has an increased risk of complications if the second procedure is performed before physiologic recovery from the first. The aims of this study were to 1) determine whether there is a time-dependent relationship between TKA staging and rates of revisions and complications and 2) identify data-driven time intervals that reduce risk of revisions and complications. METHODS: Data were collected from a national insurance database from 2015 to 2018. Staged intervals were initially assessed using fixed 6-week intervals. Stratum-specific likelihood ratio analyses were subsequently conducted to observe data-driven staging thresholds. Bivariate and multivariable regression analyses were conducted to determine the associations between the time intervals and 2-year rates of revision surgery and 90-day major complications. We included 25,527 patients undergoing staged bilateral TKA. RESULTS: In comparison to the shortest fixed time interval (1-6 weeks), as the staging interval increased the odds of 2-year all-cause revision and 90-day major complications significantly decreased (P < .05 for all). Stratum-specific likelihood ratio analysis identified 3 data-driven staging categories 1-5, 6-17, and 18-24 weeks that maximized the difference in both 2-year rates of revision and 90-day major complications. CONCLUSION: Our data showed a time-dependent relationship between the timing of TKA stages and complications. If staging is considered, a delayed interval of at least 6 weeks between procedures may significantly reduce revision and major complications. LEVEL OF EVIDENCE: Level III Therapeutic Study.

The Association of Prior Fragility Fractures on 8-Year Periprosthetic Fracture Risk Following Total Hip Arthroplasty.

BACKGROUND: Fragility fractures are often the initial clinical presentation of osteoporosis. Patients who have a history of fragility fractures undergoing total hip arthroplasty (THA) have an increased risk of 2-year postoperative complications. However, the association of recent fragility fractures with complications beyond 2 years following THA remains unknown. The purpose of this study was to characterize the association of prior fragility fractures with 8-year risks of revision THA, periprosthetic fracture (PPF), and secondary fragility fracture. METHODS: Patients aged 50 years and more who underwent THA for osteoarthritis were identified in a large national database. Patients were stratified based on whether they sustained a fragility fracture within 3 years prior to THA. There were 18,529 patients who had a prior fragility fracture and 408,753 who did not have a prior fragility fracture. Demographics and comorbidities were collected. Kaplan-Meier and Cox Proportional Hazards analyses were used to observe the cumulative incidences of all-cause revision, PPF, and secondary fragility fracture within 8 years of index surgery. RESULTS: Patients who had recent fragility fracture had significantly higher risks of revision THA (Hazard Ratio [HR] 1.7; P < .001), PPF (HR 2.2; P < .001), and secondary fragility fracture (HR 4.9; P < .001). CONCLUSION: Prior fragility fracture was shown to be a significant risk factor for revision THA, PPF, and secondary fragility fracture within 8 years of THA. Identification of these high-risk patients with an emphasis on preoperative and postoperative bone health optimization may help minimize these complications.