Normative Values for Daily Functional Recovery Patterns Following Total Knee Arthroplasty.

BACKGROUND: Wearable devices provide the ability for clinical teams to continuously monitor patients' rehabilitation progress with objective data. Understanding expected recovery patterns following total knee arthroplasty (TKA) enables prompt identification of patients failing to meet these milestones. The aim of this study was to establish normative values for daily functional recovery in the first 6 weeks after TKA using a wearable device. METHODS: This prospective study included patients who underwent TKA between 2020 and 2023, treated by 11 surgeons from 8 institutions. Eligible participants were aged 18 or older, had a primary unilateral TKA, and owned a smartphone. Knee range of motion, total daily steps, cadence, and device usage were measured continuously over 6 weeks. Statistical analysis included analysis of variance using post hoc Tukey honest significant difference tests. RESULTS: The cohort of 566 participants had a mean age of 65 and 69 for men and women, respectively (range, 50 to 80). Women comprised 61% (n = 345) of study participants. There were 82% of women and 90% of men who had a body mass index > 30. The average daily wear time of the device was 12 hours (±4) for a total of 45 days (±27). Recovery was nonlinear, with the greatest gains in the first 3 weeks postsurgery for all metrics. Men demonstrated greater total daily step counts and cadence when compared to women. Obese patients demonstrated poorer performance when compared to lower body mass index patients. CONCLUSIONS: To our knowledge, this study presents the first normative data for tracking daily functional recovery in TKA patients using wearable sensors. Standardizing the TKA recovery timeline allows surgeons to isolate factors affecting patients' healing processes, accurately counsel them preoperatively, and intervene more promptly postoperatively when rehabilitation is not within standard recovery parameters.

In-Hospital Complications and Costs of Simultaneous Bilateral Total Hip Arthroplasty: The Case for Selection and Potential Cost Savings.

Background: Published comparisons between bilateral and unilateral total hip arthroplasty (THA) remain controversial regarding the potential risks and benefits. Our objectives were to compare (1) postoperative complications and (2) resource utilization of patients having simultaneous bilateral THA with patients having unilateral procedures. Methods: The Nationwide Inpatient Sample was used to identify patients undergoing primary elective THA from January 2016 to December 2019. Complications and costs were compared between unilateral and simultaneous bilateral patients. Binary logistic regression analysis controlling demographics, comorbidities, and the primary diagnosis was performed to compare the cohorts of unilateral and bilateral patients. Results: Nine thousand nine hundred fifty-five Bilateral procedures and 785,609 unilateral procedures were identified. Patients with bilateral procedures were at increased risk for many medical complications including gastrointestinal complications (OR: 4.1; 95% CI: 2.4-6.9, P < .01), postoperative blood transfusions (OR: 3.6; 95% CI: 3.3-3.9, P < .01), and pulmonary embolisms (OR: 3.2; 95% CI: 2.0-5.1, P < .01). Patients with bilateral procedures were also at increased risk for joint complications, including periprosthetic fractures (OR: 7.4; 95% CI: 5.2-10.5, P < .01) and other mechanical complications (OR: 27.0; 95% CI: 23-30, P < .01). These patients also incurred higher index hospitalization costs ($25,347 vs $16,757, P < .001) and were discharged more commonly to a rehabilitation facility (17.8% vs 13.4%, P < .001). Conclusions: Bilateral THA are at increased risk of developing postoperative complications despite being younger and having fewer comorbidities on average when compared with unilateral patients. While bilateral patients had a higher index hospitalization cost, the overall cost of one episode of care is lower than two separate hospitalizations.

Miscoding in the Nationwide Inpatient Sample Database Raises Questions About Validity for Arthroplasty Research.

BACKGROUND: The use of administrative databases in arthroplasty research has increased over the past decade. The Nationwide Inpatient Sample (NIS) is one of the first and most frequently used. Despite many published articles using this dataset, there exists no standardization resource accounting for the potential of biased results. The purpose of our study was to assess the amount of discordant data between clinically relevant variables and propose a standard for using this database in primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). METHODS: An initial set of patients undergoing total joint arthroplasty were identified from the NIS between 2016 and 2019 using the International Classification of Diseases, 10th Revision, Procedure Coding System. All records with THA and TKA in any of the procedure variables (PR1-PR20) were included. A total of 63 relevant and consistent variables were selected for individual comparison including diagnosis-related group (1), elective (1), procedure codes (20), day of main procedure (1), and diagnosis codes (40). Descriptive statistics were used. A total of 3,562,819 patients were included in the initial set. RESULTS: Using diagnosis-related groups, 5.3% were revision surgeries, 4.7% were not elective, 2.3% did not have THA or TKA as their primary procedure for hospitalization, and 2.9% of THA and 9.7% of TKA were bilateral. A total of 6.2% of the surgeries were done day(s) before or after admission, and 10.8% of THA and 6.3% of TKA were missing an orthopedic diagnosis for admission. Many had multiple orthopedic diagnoses for admission, 3.2% of THA and 0.7% of TKA. Overall miscoding was 23.3%. CONCLUSIONS: Using the NIS without standardized data processing to study elective, unilateral, primary THA and TKA introduces major bias. A logical and stepwise approach to curate the data before analysis is proposed to improve research quality when using this database in hip and knee arthroplasty studies.

Varying Complication Rates and Increased Costs in Technology-Assisted Total Hip Arthroplasty Versus Conventional Instrumentation in 1,372,300 Primary Total Hips.

BACKGROUND: The use of technology allows surgeons increased precision in component positioning in total hip arthroplasty (THA). The objective of this study was to compare (1) perioperative complications and (2) resource utilizations between robotic-assisted (RA) and computer-navigated (CN) versus conventional instrumenttaion (CI) THA. METHODS: A retrospective cohort study was performed using a large national database to identify patients undergoing unilateral, primary elective THA from January 1, 2016 to December 31, 2019 using RA, CN, or CI. There were 1,372,300 total patients identified and included RA (29,735), CN (28,480), and CI (1,314,085) THA. Demographics, complications, lengths of stay, dispositions, and costs were compared between the cohorts. Binary logistic regression analyses were performed. RESULTS: The use of RA THA led to lower rates of intraoperative fracture (0.22% versus 0.39%), delirium (0.1% versus 0.2%), postoperative anemia (14.4% versus 16.7%), higher myocardial infarction (0.13% versus 0.08%), renal failure (1.7% versus 1.6%), blood transfusion (2.0% versus 1.9%), and wound dehiscence (0.02% versus 0.01%) compared to CI THA. The use of CN led to lower rates of respiratory complication (0.5% versus 0.8%), renal failure (1.1% versus 1.6%), blood transfusion (1.3% versus 1.9%), and pulmonary embolism (0.02% versus 0.1%) compared to CI THA. Total costs were increased in RA ($17,729 versus $15,977) and CN ($22,529 versus $15,977). Lengths of hospital stay were decreased in RA (1.8 versus 1.9 days) and CN (1.7 versus 1.9 days). CONCLUSIONS: Perioperative complication rates vary in technology-assisted THA, with higher rates in RA THA and lower rates in CN THA, relative to CI THA. Both RA THA and CN THA were associated with more costs, shorter postoperative hospital stays, and higher rates of discharge home compared to CI THA.

Lower Perioperative Complication Rates and Shorter Lengths of Hospital Stay Associated With Technology-Assisted Total Knee Arthroplasty Versus Conventional Instrumentation in Primary Total Knee Arthroplasty.

BACKGROUND: The use of technology allows increased precision in component positioning in total knee arthroplasty (TKA). The objectives of this study were to compare (1) perioperative complications and (2) resource utilization between robotic-assisted (RA) and computer-navigated (CN) versus conventional (CI) TKA. METHODS: A retrospective cohort study was performed using a national database to identify patients undergoing unilateral, primary elective TKA from January 2016 to December 2019. A total of 2,174,685 patients were identified and included RA (69,445), CN (112,225), or CI (1,993,015) TKA. Demographics, complications, lengths of stay, dispositions, and costs were compared between the cohorts. Binary logistic regression analysis was performed. RESULTS: The RA TKA cohort had lower rates of intraoperative fracture (0.05 versus 0.08%, P < .05), respiratory complications (0.6 versus 1.1%, P < .05), renal failure (1.3 versus 1.7%, P < .05), delirium (0.1 versus 0.2%, P < .05), gastrointestinal complications (0.04 versus 0.09%, P < .05), postoperative anemia (8.9 versus 13.9%, P < .05), blood transfusion (0.4 versus 0.9%, P < .05), pulmonary embolism, and deep vein thrombosis (0.1 versus 0.2%, P < .05), and mortality (0.01 versus 0.02%, P < .05) compared to conventional TKA, though the cohort did have higher rates of myocardial infarction (0.09 versus 0.07%, P < .05). The CN cohort had lower rates of myocardial infarction (0.02 versus 0.07%, P < .05), respiratory complications (0.8 versus 1.1%, P < .05), renal failure (1.5 versus 1.7%, P < .05), blood transfusion (0.8 versus 0.9%, P < .05), pulmonary embolism (0.08 versus 0.2%, P < .05), and deep vein thrombosis (0.2 versus 0.2%, P < .05) over CI TKA. Total cost was increased in RA (16,190 versus $15,133, P < .05) and CN (17,448 versus $15,133, P < .05). However, the length of hospital stay was decreased in both RA (1.8 versus 2.2 days, P < .05) and CN (2.1 versus 2.2 days, P < .05). CONCLUSIONS: Technology-assisted TKA was associated with lower perioperative complication rates and faster recovery.

Increased Risk of In-Hospital Complications and Costs After Total Hip Arthroplasty for Primary and Secondary Osteonecrosis.

BACKGROUND: An increasing proportion of patients are undergoing total hip arthroplasty (THA) for osteonecrosis (ON). Comorbid conditions and surgical risk factors are known to be greater in ON patients compared with patients who have osteoarthritis (OA) alone. The purpose of our study was to quantify the specific in-hospital complications and resource utilization associated with patients undergoing THA for ON versus OA. METHODS: A large national database was queried to identify patients undergoing primary THA from January 1, 2016 to December 31, 2019. A total of 1,383,880 OA, 21,080 primary ON, and 54,335 secondary ON patients were identified. Demographics, in-hospital complications, costs, lengths of stay, and discharge dispositions for primary and secondary ON cohorts were compared to OA only. Age, race, ethnicity, comorbidities, Medicaid, and income status were controlled with binary logistic regression analyses. RESULTS: The ON patients were often younger, African American or Hispanic, and had more comorbidities. Those undergoing THA for primary and secondary ON had a significantly higher risk of perioperative complications, including myocardial infarction, postoperative blood transfusion, and intraoperative bleeding. Total hospital costs and lengths of stay were significantly higher for both primary ON and secondary ON and both cohorts were less likely to be discharged home. CONCLUSION: While rates of most complications have decreased over recent decades in ON patients undergoing THA, the ON patients still have worse outcomes even when controlling for comorbidity differences. Bundled payment systems and perioperative management strategies for these different patient cohorts should be considered separately.

Prevalence and Spectrum of Occupational Injury Among Orthopaedic Surgeons: A Cross-Sectional Study.

Orthopaedic surgeons are at increased risk for many occupational hazards, both physical and mental. The aim of this study was to evaluate a wide range of work-related injuries among orthopaedic surgeons in the United States. Methods: An electronic survey was developed to assess both physical and mental occupational hazards among orthopaedic surgeons. Descriptive statistics were analyzed for all survey items and compared using chi-square and paired t tests, as appropriate. Results: The 1,645 responding orthopaedic surgeons (7% response rate) reported a total of 2,702 work-related musculoskeletal injuries, 17.9% of which required surgical treatment. Of the 61 who filed a disability claim, only 66% returned to work and 34% retired early. Additionally, 17.4% of respondents reported having been diagnosed with cancer since starting practice, and 93.8% reported experiencing a finger stick at some point in their career. Over one-half (55.8%) had experienced feelings of psychological distress since beginning practice, and nearly two-thirds (64.4%) reported burnout from work. Conclusions: This study captured a spectrum of occupational injuries that pose longitudinal risks to an orthopaedic surgeon's physical and mental well-being. Our hope is that this analysis of occupational hazards will help to raise awareness among the orthopaedic and medical communities and lead to efforts to reduce these risks. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Chronic Opioid Use Independently Increases Complications and Resource Utilization After Primary Total Joint Arthroplasty.

BACKGROUND: Current literature suggests a link between the chronic use of opioids and musculoskeletal surgical complications. Given the current opioid epidemic, the need to elucidate the effects of chronic opioid use (OD) on patient outcomes and cost has become important. The purpose of this study was to determine if OD is an independent risk factor for inpatient postoperative complications and resource utilization after primary total joint arthroplasty. METHODS: A total of 3,545,565 patients undergoing elective, unilateral, primary total hip (THA) and knee (TKA) arthroplasty for osteoarthritis from January 2016 to December 2019 were identified using a large national database. In-hospital postoperative complications, length of stay, and total costs adjusted for inflation in opioid + patients were compared with patients without chronic opioid use (OD). Logistic regression analyses were used to control for cofounding factors. RESULTS: OD patients undergoing either THA or TKA had a higher risk of postoperative complications including respiratory (odds ratio (OR): 1.4 and OR: 1.3), gastrointestinal (OR: 1.8 and OR: 1.8), urinary tract infection (OR: 1.1 and OR: 1.2), blood transfusion (OR: 1.5 and OR: 1.4), and deep vein thrombosis (OR: 1.7 and OR: 1.6), respectively. Total cost ($16,619 ± $9,251 versus $15,603 ± $9,181, P < .001), lengths of stay (2.15 ± 1.37 versus 2.03 ± 1.23, P < .001), and the likelihood for discharge to a rehabilitation facility (17.8 versus 15.7%, P < .001) were higher in patients with OD. CONCLUSION: OD was associated with higher risk for in-hospital postoperative complications and cost after primary THA and TKA. Further studies to find strategies to mitigate the impact of opioid use on complications are required.

Relative frequency of primary total hip arthroplasty for avascular necrosis in the United States as compared to a regional center: A data review.

Background: The relative frequencies of indications for primary total hip arthroplasty (THA) are not well-established. This study aims to establish the incidence of THA performed for Avascular Necrosis of the hip (AVN), as well as the other most common indications for THA in the United States, as compared to the incidences at a high-volume tertiary referral center in Miami, Florida. We hypothesize that the relative incidence of AVN and each other indication for THA will vary significantly between the United States as a whole and the tertiary referral center. Methods: A query of the 2016-2017 National Inpatient Sample (NIS) and a tertiary referral center adult reconstruction registry was completed. The relative frequencies of each indication for THA, demographics, and behavioral risk factors were analyzed. Results: 225,061 primary THA patients in the National Inpatient Sample database and 447 in the Miami tertiary referral center database were included in the final analysis. The proportion of primary THA for AVN in the NIS database (5.97%) was significantly lower than the same proportion in the tertiary referral center database (22.2%), p < .001. There was no significant difference in the incidence of primary THA for osteoarthritis, inflammatory arthritis, or hip dysplasia between the two populations. Conclusion: The incidence of THA for AVN is significantly different between a tertiary referral center and the greater United States. Patient demographics, race, and behavioral risk factors are associated with the disparity. Orthopaedic surgeons should recognize the differences in THA indication between populations when counseling patients on treatments, outcomes, and the most current literature.

Hospital Volume as a Source of Variation for Major Complications and Early In-Hospital Mortality After Total Joint Arthroplasty.

Background: Although the effects of hospital volume on mortality have been studied in other procedures, data on total joint arthroplasty (TJA) are limited. Furthermore, mortality rate among surgical patients with early major complications has become an important patient safety indicator and has been shown to be an important driver of mortality in certain operations. Our objective was to examine the effect of hospital volume on early complications and in-hospital mortality rate after TJA. Material and methods: A total of 5,396,644 patients undergoing elective, unilateral TJA between 2002 and 2011 were identified using the Nationwide Inpatient Sample database. Hospitals were divided by annual volume into tertiles. Major complications associated with postoperative mortality were identified. Risk-adjusted mortality (RAM) was calculated to adjust for hospital case mix. Results: For THAs performed at high-volume centers, RAM was significantly lower (0.03% vs 0.41%, P < .05, high vs low volume) with lower prevalence of major complications (2.2% vs 3.3%, P < .05, high vs low volume). We observed similar results for TKA where RAM was lower (<0.01% vs 0.06%, P < .05, high vs low volume). Major complications, however, were not significant (1.4% vs 1.5%, P < .83). Pneumonia was the most prevalent complication for THA (1.5% vs 0.9%, P < .05, high vs low volume) and TKA (0.9% vs 0.5%, P < .05 high vs low volume). Conclusion: Hospital volume appears to drive a large proportion of the variation in early in-hospital mortality after TJA. This variation does not seem to be explained by hospital case mix and rather by the higher prevalence of major postoperative complications in lower volume institutions.

Inhospital Complications and Costs of Simultaneous Bilateral Total Knee Arthroplasty: The Case for Selection and Potential Cost Savings.

BACKGROUND: Published comparisons between bilateral and unilateral total knee arthroplasties (TKAs) remain biased, as most patients undergoing bilateral TKA are prescreened and healthier than average patients having unilateral procedures. Our objectives were to compare postoperative complications and resource utilization of patients having simultaneous bilateral TKAs with similar patients having unilateral procedures. METHODS: The Nationwide Inpatient Sample (NIS) database was used to identify patients undergoing primary elective TKA from 2002 to 2011. A total of 4,445,263 patients were identified. Of these, 190,783 (4%) were having same-day bilateral procedures. Patients with staged bilateral TKA during the same hospitalization were excluded. Complications and costs were compared to a matched cohort of patients having unilateral procedures. This cohort was matched based on age, gender, and 30 comorbid-defined elements in the NIS. RESULTS: A total of 172,366 (90%) simultaneous bilateral procedures were matched 1:1 to patients with unilateral procedures for the adjusted analysis. Patients with bilateral procedures were at an increased risk for many complications including postoperative anemia (OR: 2.3; 95% CI: 2.2-2.3, P < .001), cardiac (OR: 2.1; 95% CI: 2.0-2.3, P < .001), and inhospital mortality (OR: 3.3; 95% CI: 2.6-4.3). These patients also incurred in higher hospital costs ($19,343 vs $12,852, P < .001) and were discharged more commonly to a rehabilitation facility (70% vs 32%, P < .001). CONCLUSION: Patients undergoing simultaneous bilateral TKA are at an increased risk of developing important postoperative complications and mortality compared with unilateral cases. These data highlight the importance of patient selection and optimization for bilateral TKA and potential cost savings.

Increased Morbidity With Diagnosis and Treatment of Pulmonary Embolism After Total Joint Arthroplasty: A Matched Control Analysis of 30,000 Patients.

BACKGROUND: Currently, the risks associated with the diagnosis of pulmonary embolism (PE) and subsequent treatment are not well known. The purpose of our study is to quantify the specific in-hospital complications and resource utilization of patients with PE following total joint arthroplasty when compared to a matched cohort. METHODS: The Nationwide Inpatient Sample database was used to identify patients undergoing primary hip and knee arthroplasty from January 1993 to December 2008. PE was determined using International Classification of Diseases, Ninth Revision, Clinical Modification codes. In-hospital complications, costs, and length of stay for patients with PE were compared to patients without PE, matched on the basis of age, gender, procedure (total hip arthroplasty vs total knee arthroplasty), year of surgery, morbid obesity, and all 28 comorbid-defined elements of the Elixhauser Comorbidity Index. RESULTS: Of 8,634,038 procedures, 30,281 (0.4%) patients had a PE after total joint arthroplasty. In total, 29,917 (98%) were matched one-to-one with patients without PE. Patients with PE had a substantially higher risk of all postoperative in-hospital complications: deep vein thrombosis (odds ratio [OR] 17), peripheral vascular (OR 34), hematoma (OR 3.7), and gastrointestinal bleeding (OR 7.0) (all P < .001). Mortality was significantly higher in patients with PE compared to patients without PE (3.4% vs 0.1%, OR 30), along with total hospital costs, lengths of stay, and rates of discharge to rehabilitation facilities. CONCLUSION: After controlling for comorbidities patients with PE have a significantly higher risk for complications including in-hospital mortality and higher hospital costs when compared to patient without PE.

Time-Driven Activity-Based Costing in Preoperative Tasks for Total Hip and Knee Arthroplasty.

BACKGROUND: Substantial work in the preoperative phase of total hip arthroplasty (THA) and total knee arthroplasty (TKA) is unaccounted for in current Relative Value Scale Update Committee methodology. A Time-Driven Activity-Based Costing (TDABC) analysis allows for an accurate assessment of the preoperative costs associated with total joint replacement surgery. METHODS: The mean time that clinical staff members spent on preoperative tasks per patient was multiplied by the hourly salary. Clinical staff members included orthopedic surgeons, nurse practitioners or physician assistants, nurses, medical assistants, and surgical coordinators. Mean time spent on preoperative tasks was obtained from the most recent literature. Salaries were obtained from the nationwide database provided by Glassdoor Inc. RESULTS: Total time spent among clinical staff involved in preoperative tasks for each arthroplasty patient was 8.45 hours (2.96-13.94). Total TDABC was calculated to be $348.17 (132.46-562.64). Accounting for preoperative tasks, the TDABC for TKA/THA increases from $13321.5 to $13669.67. Preoperative tasks are composed of 2.6% of total TKA/THA TDABC. In 2020, an estimated $544,189,710 of preoperative TKA/THA work was completed. CONCLUSION: Surgeons, providers, and ancillary staff involved in THA/TKA spend a cumulative preoperative work time of approximately 8.5 hours per patient, which equates to $348.17 that is currently unaccounted for in Relative Value Scale Update Committee methodology.

Perioperative Complications in Patients With Inflammatory Arthropathy Undergoing Total Hip Arthroplasty.

BACKGROUND: Limited information exists comparing the short-term complications of the different inflammatory arthropathies (IAs) after total hip arthroplasty (THA). Our objectives were to (1) compare perioperative complications and (2) determine the most common complications between the different IA subtypes compared with patients with osteoarthritis (OA) undergoing primary THA. METHODS: The Nationwide Inpatient Sample was used to identify 2,102,238 patients undergoing elective, unilateral THA between 2002 and 2011. Of these, 86,671 (4%) had an IA, including rheumatoid arthritis (RA), psoriatic arthritis, juvenile idiopathic arthritis (JIA), ankylosing spondylitis (AS), and systemic lupus erythematosus (SLE). Preoperative diagnosis, comorbidities, and postoperative complications were determined using International Classification of Disease Clinical Modification version 9 codes. The prevalence of in-hospital medical and orthopedic complications was compared between patients with an IA and OA. RESULTS: When compared with patients with OA, patients with RA, JIA, SLE, and AS had significantly more inpatient medical and orthopedic complications immediately after THA (P < .01). Patients with JIA had the highest orthopedic complication rate (2.8%). Specific orthopedic complications by subtype included wound dehiscence for RA and AS periprosthetic fractures for JIA and increased mortality for SLE patients. There were no significant differences in medical or orthopedic complications seen in patients with psoriatic arthritis. CONCLUSION: Differences exist in postoperative inpatient medical and orthopedic complications among patients with different types of IAs after THA. Our results point out the importance of preoperative optimization in patients with IA and monitoring for selective postoperative complications.

Total Joint Arthroplasty: A Granular Analysis of Outcomes in the Economically Disadvantaged Patient.

BACKGROUND: Poor patients experience more serious complications and worse outcomes after surgery than higher-income patients. Our objective was to study detailed patient sociodemographic characteristics and preoperative/postoperative patient-oriented outcomes in economically disadvantaged and non-economically disadvantaged primary total joint arthroplasty patients. METHODS: From a consecutive series, 213 economically disadvantaged patients and 1940 non-economically-disadvantaged patients were statistically analyzed. Baseline sociodemographic characteristics and pain visual analog scale, Quality of Well-Being Index 7, Short Form 36, and Western Ontario and McMaster Universities Arthritis Index scores recorded before and after surgery were compared between both groups controlling for baseline differences. Minimum follow-up was 1 year. RESULTS: Economically disadvantaged patients were significantly younger, more likely to be disabled, and had worse preoperative and postoperative scores. CONCLUSION: When compared with non-economically disadvantaged patients, economically disadvantaged patients consistently had lower function and worse quality of life before and after total joint arthroplasty.

Assessment of Damage on a Dual Mobility Acetabular System.

BACKGROUND: Dual mobility designs were introduced to increase stability and reduce the risk of dislocation, both being common reasons for surgical revision after total hip arthroplasty. The in vivo behavior of dual mobility constructs remains unclear, and to our knowledge, no data have been published describing in vivo surface damage to the polyethylene bearing surfaces. METHODS: We used surface damage assessed on the inner and outer polyethylene bearing surfaces in 33 short-term retrieved dual mobility liners as evidence of relative motion at the 2 bearings. A lever out test was performed to determine the force required for dislocation of the cobalt-chromium femoral head from the polyethylene liner. RESULTS: Both bearings showed damage; however, the inner polyethylene bearings had higher damage scores, lower prevalence of remaining machining marks, and higher incidence of concentric wear, all consistent with more motion at the inner polyethylene bearing. The inner polyethylene bearings also had a higher occurrence of embedded titanium debris. The damage sustained in vivo was insufficient to lead to intraprosthetic dislocation in any of the retrieved components. Lever out tests of 12 retrievals had a mean dislocation load of 261 ± 52 N, which was unrelated to the length of implantation. CONCLUSION: Our short-term retrieval data of 33 highly cross-linked polyethylene dual mobility components suggest that although motion occurs at both bearing articulations, the motion of the femoral head against the inner polyethylene bearing dominates. Although damage was not severe enough to lead to intraprosthetic dislocation, failure may occur long term and should be assessed in future studies.

Perioperative Complications in Patients with Inflammatory Arthropathy Undergoing Total Knee Arthroplasty.

Little data exists comparing acute post-operative outcomes in patients with different types of inflammatory arthritis (IA) after undergoing a total knee arthroplasty (TKA). Our objectives were to compare perioperative complications and determine the most common complications between the different IA subtypes compared with patients with osteoarthritis undergoing primary TKA. We found significant differences when comparing complications within the different subtypes of IA. RA patients, despite having a greater number of comorbidities had a reduced rate of medical complications postoperatively compared to the OA cohort. All of the inflammatory subtypes had a higher rate of orthopedic complications postoperatively compared to the OA group except for patients with AS. However, ankylosing spondylitis had the highest mortality rate as well as medical complication rate among the subtypes.

Lack of early dislocation following total hip arthroplasty with a new dual mobility acetabular design.

Dual mobility implant designs minimise the risk of dislocation without sacrificing range of motion. Between 1st September 2008 and 31st July 2011, 5 institutions examined early clinical outcomes of a new dual mobility bearing hip system implanted in 485 primary THAs in 452 patients. Patient demographics were 46% female, a mean age of 67 years and a mean BMI of 30. Complications at a minimum of 2 years after surgery included 1 femur fracture, 1 DVT and 4 unrelated deaths. There were no dislocations. For functional outcomes, Harris Hip Scores increased from 41 to 86 (p<0.001), while VAS pain scores decreased from 5.9 to 0.7 (p<0.001). Minimal complications, excellent early clinical outcomes and the absence of early dislocations demonstrate the improved stability of this dual mobility implant system.

The John Insall Award: Morbid obesity independently impacts complications, mortality, and resource use after TKA.

BACKGROUND: The importance of morbid obesity as a risk factor for complications after total knee arthroplasty (TKA) continues to be debated. Obesity is rarely an isolated diagnosis and tends to cluster with other comorbidities that may independently lead to increased risk and confound outcomes. It is unknown whether morbid obesity independently affects postoperative complications and resource use after TKA. QUESTIONS/PURPOSES: The purpose of this study was to determine whether morbid obesity is an independent risk factor for inpatient postoperative complications, mortality, and increased resource use in patients undergoing primary TKA. METHODS: The Healthcare Cost and Utilization Project Nationwide Inpatient Sample (NIS) database was used to identify patients undergoing primary TKA from October 2005 to December 2008. Morbid obesity (body mass index≥40 kg/m2) was determined using International Classification of Diseases, 9th Revision, Clinical Modification codes. In-hospital postoperative complications, mortality, costs, and disposition for morbidly obese patients were compared with nonobese patients. To control for potential confounders and comorbid conditions, each morbidly obese patient was matched to a nonobese patient using age, sex, and all 28 comorbid-defined elements in the NIS database based on the Elixhauser Comorbidity Index. Of 1,777,068 primary TKAs, 98,410 (5.5%) patients were categorized as morbidly obese. Of these, 90,045 patients (91%) were able to be matched one-to-one to a nonobese patient for the adjusted analysis. RESULTS: Morbidly obese patients had a higher risk of postoperative in-hospital infection (0.24% versus 0.17%; odds ratio [OR], 1.3; 95% confidence interval [CI], 1.1-1.7; p=0.001), wound dehiscence (0.11% versus 0.08%; OR, 1.3; 95% CI, 1.0-1.7; p=0.28), and genitourinary-related complications (0.60% versus 0.44%; OR, 1.3; 95% CI, 1.1-1.5; p<0.001). There was no increase in the prevalence of cardiovascular or thromboembolic-related complications. Morbidly obese patients were at higher risk of in-hospital death after primary TKA compared with nonobese patients (0.08% versus 0.02%; OR, 3.2; 95% CI, 2.0-5.2; p<0.001). Total hospital costs (USD 15,174 versus USD 14,715, p<0.001), length of stay (3.6 days versus 3.5 days, p<0.001), and rate of discharge to a facility (40% versus 30%, p<0.001) were all higher in morbidly obese patients. CONCLUSIONS: Morbid obesity appears to be independently associated with a higher risk for a small number of select in-hospital postoperative complications and mortality after matching for comorbid medical conditions linked to obesity. However, the independent impact of morbid obesity appears to be fairly modest, and morbid obesity did not appear to be an independent risk factor for many systemic complications. Continued research is necessary to identify the influence of associated comorbidities on early postoperative complications in morbidly obese patients after TKA. LEVEL OF EVIDENCE: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Medicaid payer status is associated with in-hospital morbidity and resource utilization following primary total joint arthroplasty.

BACKGROUND: Previous reports suggest that there are major disparities in outcomes following total joint arthroplasty among patients with different payer statuses. The explanation for these differences is largely unknown and may result from confounding variables. The Affordable Care Act expansion of Medicaid coverage in 2014 makes the examination of these disparities particularly relevant. METHODS: The Healthcare Cost and Utilization Project (HCUP) Nationwide Inpatient Sample (NIS) database was used to identify patients who had undergone primary hip or knee arthroplasty from 2002 through 2011. Complications, costs, and length of hospital stay for patients with Medicaid were compared with those for non-Medicaid patients. Each Medicaid patient was matched to a non-Medicaid patient according to age, sex, race, type of total joint arthroplasty, procedure year, hospital characteristics, smoking status, and all twenty-nine comorbidities defined in the NIS-modified Elixhauser comorbidity measure. RESULTS: It was determined that 191,911 patients who underwent total joint arthroplasty had Medicaid payer status (2.8% of the entire total joint arthroplasty population), and 107,335 (56%) of these Medicaid patients were matched one to one to a non-Medicaid patient for all variables for the adjusted analysis. After matching, Medicaid patients were found to have a higher prevalence of postoperative in-hospital infection (odds ratio [OR], 1.7; 95% confidence interval [CI], 1.3 to 2.1), wound dehiscence (OR, 2.2; 95% CI, 1.4 to 3.4), and hematoma or seroma (OR, 1.3; 95% CI, 1.2 to 1.4) but a lower risk of cardiac complications (OR, 0.7; CI, 0.6 to 0.9). The length of the hospital stay was longer, total cost was higher, and discharge to an inpatient facility was more frequent for patients with Medicaid status (p < 0.01). CONCLUSIONS: Compared with non-Medicaid patients, Medicaid patients have a significantly higher risk for certain postoperative in-hospital complications and consume more resources following total joint arthroplasty even when the two groups have been matched for patient-related factors and comorbid conditions commonly associated with low socioeconomic status. Additional work is needed to understand the complex interplay between socioeconomic status and outcomes, to ensure appropriate resources are allocated to maintain access for this patient population, and to develop appropriate risk stratification.