Planovalgus Foot Deformity in Patients Undergoing Total Hip Arthroplasty Is Associated With Increased Risk of Falls, Implant-Related Complications, and Revisions: A Case-Control Analysis.

BACKGROUND: Pes planus occurs due to the loss of the longitudinal arch of the foot, resulting in altered gait mechanics. This may lead to increased complications following total hip arthroplasty (THA). Thus, the aim of this study was to assess the effects that pes planus has on rates of falls, implant complications, fall-related injuries, and times to revision among THA patients. METHODS: A retrospective review of a private insurance claims database was conducted from 2010 to 2021. Patients who had a diagnosis of congenital or acquired pes planus and cases of THA were identified. Patients undergoing THA with a diagnosis of pes planus were matched to control patients 1:5 based on age, sex, and comorbidity profiles. Logistic regression was utilized to assess for differences in complication rates. RESULTS: A total of 3,622 pes planus patients were matched to 18,094 control patients. The pes planus group had significantly higher rates of falls than the control group (6.93 versus 2.97%, OR [odds ratio]: 2.43; CI [confidence interval]: 2.09 to 2.84; P < .001). Pes planus patients also had significantly greater odds of dislocation (OR: 1.89; CI: 1.58 to 2.27; P < .001), mechanical loosening (OR: 2.43; CI: 2.09 to 2.84; P = .019), and periprosthetic fracture (OR: 2.43; CI: 2.09 to 2.84; P < .001). The pes planus group had significantly greater rates of proximal humerus fractures (P = .008), but no difference was seen in distal radius fractures (P = .102). The time to revision was significantly shorter in the pes planus group (190 versus 554 days, P < .001). CONCLUSIONS: Pes planus in patients undergoing THA is associated with increased risk of complications and faster time to revision. These findings may allow orthopaedic surgeons to identify those patients at risk and allow for more educated patient counseling and operative planning.

Medial Varus Proximal Tibial Resection is Superior to Pie-Crusting of the Medial Collateral Ligament During Primary Total Knee Arthroplasty.

BACKGROUND: Medial varus proximal tibial (MPT) resection or soft tissue releases (STRs) of the medial collateral ligament (MCL) in the form of pie-crusting can be performed to achieve a balanced knee in a varus deformity. Studies comparing the 2 modalities have not been addressed within the literature. Therefore, the aims of this study were to assess the following: (1) compartmental changes between the 2 methods and (2) changes in patient-reported outcome measurements. METHODS: Using our institution's total joint arthroplasty registry, patients who underwent primary total knee arthroplasty from January 1, 2017, to December 31, 2019, were identified. The MPT resection and STR patients were 1:1 matched with baseline parameters yielding 196 patients. Outcomes of interest included: changes in compartmental pressures at 10, 45, and 90° degrees and change to the Short-Form 12, Western Ontario and McMaster Universities Osteoarthritis Index, and Forgotten Joint Scores (FJSs) at the 2-year follow-up period. A P value less than .05 was used as our threshold for statistical difference. RESULTS: The MPT resection led to significant reductions in compartmental pressures at 10° [43 versus 19 pounds (lbs.), P < .0001], 45° (43 versus 27 lbs., P < .0001), and 90° degrees (27 versus 16 lbs., P < .0001) compared to STR. MPT resection also had significantly improved Short-Form 12 (47 versus 38, P < .0001), Western Ontario and McMaster Universities Osteoarthritis Index (9 versus 21, P < .0001), and Forgotten Joint Score (79 versus 68, P = .005). CONCLUSION: Bone modification was superior to pie-crusting of the MCL in achieving consistent pressure balancing and improved outcomes. The investigation can guide surgeons on the preferred method to achieve a well-balanced knee.

Risk of Periprosthetic Joint Infection After Intra-Articular Corticosteroid Injection Following Unicompartmental Knee Arthroplasty.

BACKGROUND: Perioperative intra-articular joint injection is a known risk factor for developing prosthetic joint infection (PJI) in the immediate preoperative and postoperative periods for total knee arthroplasty, but is less defined in unicompartmental knee arthroplasty (UKA). The goal of this study was to elucidate the risk of developing PJI after intra-articular corticosteroid injection (IACI) into a post UKA knee. METHODS: A retrospective review of a nationwide administrative claims database was performed from January 2015 to October 2020. Patients who underwent UKA and had an ipsilateral IACI were identified and matched 2:1 to a control group of primary UKA patients who did not receive IACI. Multivariate logistic analyses were conducted to assess differences in PJI rates at 6 months, 1 year, and 2 years. RESULTS: A total of 47,903 cases were identified, of which 2,656 (5.5%) cases received IACI. The mean time from UKA to IACI was 355 days. The incidence of PJI in the IACI group was 2.7%, compared to 1.3% in the control group. The rate of PJI after IACI was significantly higher than the rate in the control group at 6 months, 1 year, and 2 years (all P < .05). The majority of PJI occurred within the first 6 months following IACI (75%). CONCLUSION: In this study, IACI in a UKA doubled the risk of PJI compared to patients who did not receive an injection. Surgeons should be aware of this increased risk to aid in their decision-making about injecting into a UKA. LEVEL OF EVIDENCE: III, retrospective comparative study.

Morbidly Obese Patients Undergoing Unicompartmental Knee Arthroplasty Compared to Total Knee Arthroplasty: A Retrospective Case-Controlled Analysis.

BACKGROUND: In this study, we assess the effects that morbid obesity (body mass index (BMI) ≥ 40) has on: (1) Ninety-day medical complications and readmission rates; (2) costs of care and lengths of stay (LOS); and (3) 2-year implant complications in patients undergoing unicompartmental knee arthroplasty (UKA) versus total knee arthroplasty (TKA). METHODS: A retrospective query of TKA and UKA patients were identified using a national database. Morbidly obese UKA patients were matched 1:5 to morbidly obese TKA patients by demographic and comorbidity profiles. Subgroup analyses were conducted using the same process between morbidly obese UKA patients and BMI <40 TKA patients, as well as to BMI <40 UKA patients. RESULTS: Morbidly obese patients who underwent UKA had significantly fewer medical complications, readmissions, and periprosthetic joint infections than TKA patients; however, UKA patients had greater odds of mechanical loosening (ML). The TKA patients had significantly longer LOS (3.0 versus 2.4 days, P < .001), as well as significantly greater costs of care than UKA patients ($12,869 versus $7,105). Morbidly obese UKA patients had similar rates of medical complications, and significantly lower readmissions, decreased LOS, and decreased costs when compared to TKA patients who had a BMI <40. CONCLUSION: In patients who have morbid obesity, complications were decreased in UKA compared to TKA. Moreover, morbidly obese UKA patients had lower medical utilizations and similar complication rates when compared to TKA patients with the recommended cutoff of BMI <40. However, UKA patients had greater rates of ML than TKA patients. A UKA may be an acceptable treatment option for unicompartmental osteoarthritis in morbidly obese patients.

Patients With Previous COVID-19 Infection Can Safely Undergo Primary Total Joint Arthroplasty.

BACKGROUND: The COVID-19 virus is believed to increase the risk of diffusing intravascular coagulation. Total joint arthroplasty (TJA) is one of the most common elective surgeries and is also associated with a temporarily increased risk of venous thromboembolism (VTE). However, the influence of a history of COVID-19 infection on perioperative outcomes following TJA remains unknown. Therefore, this study sought to determine what effect a history of COVID-19 infection had on outcomes following primary TJA. METHODS: A retrospective case-control study using the national database was performed to identify all patients who had a history of COVID-19 and had undergone TJA, between 2019 and 2020. Patients who had a history of both were 1:1 matched to those who did not have a history of COVID-19, and 90-day outcomes were compared. A total of 661 TKA and 635 THA patients who had a history of COVID-19 were 1:1 matched to controls. There were no differences in demographics and comorbidities between the propensity-matched pairs in both TKAs and THAs studied. Previous COVID-19 diagnosis was noted in 28.3% of patients 5 days within TJA and in 78.6%, 90 days before TJA. RESULTS: Patients who had a previous diagnosis of COVID-19 had a higher risk of pneumonia during the postoperative period for both THA and TKA (6.9% versus 3.5%, P < .001 and 2.27% versus 1.21%, P = .04, respectively). Mean lengths of stay were also greater for those with a previous COVID-19 infection in both cohorts (TKA: 3.12 versus 2.57, P = .027, THA: 4.52 versus 3.62, P < .001). Other postoperative outcomes were similar between the 2 groups. CONCLUSION: COVID-19 infection history does not appear to increase the risk of VTE following primary TJA, but appears to increase the risk of pneumonia in addition to lengths of stay postoperatively. Individual risk factors should be discussed with patients, to set reasonable expectations regarding perioperative outcomes.

Mid-Term Survivorship, Radiographic and Functional Outcomes of Robotic-Assisted Unicompartmental Knee Arthroplasty.

INTRODUCTION: The use of robotic-arm assistance for medial unicompartmental knee arthroplasty (RAUKA) has become an area of interest to overcome technical challenges, improve accuracy, and optimize patient outcomes. Due to the rise in osteoarthritis (OA) and robotic assistance, well-powered long-term studies are warranted. The aim of this study was to analyze midterm survivorship, radiographic changes, range of motion (ROM), and patient-reported outcome measurements (PROMs) of RAUKA. MATERIALS AND METHODS: Patients who underwent RAUKA for medial compartmental OA were identified from April 2009 to May 2014. The query yielded 162 knees with a mean follow up of 6.5 years. Primary endpoints were to compare survivorship, final mechanical axis alignment, radiographic changes, mean ROM, and changes to the following PROMs: Knee Society Score (KSS), International Knee Documentation Committee (IKDC), and Oxford Knee Score (OKS). Statistical analyses were primarily descriptive. A p-value less than 0.05 was considered statistically significant. RESULTS: There were no revisions of the primary implant, one case required exchange of polyethylene bearing and debridement for deep infection, and five cases required additional surgical intervention with implant retention. Overall survivorship was 100%. Radiographic assessment demonstrated no mechanical loosening or osteolysis surrounding the implant. Mean ROM was 3 to 121.9º. Patients demonstrated a mean functional KSS of 78.55, IKDC of 78.22, and OKS of 43.94. CONCLUSIONS: The study supports excellent mid-term outcomes in patients undergoing RAUKA for medial compartment OA. Longer term follow-up studies are necessary to determine the efficacy of this technology for patients undergoing RAUKA for medial compartment OA.

Robotic-Arm Assisted Lateral Unicompartmental Knee Arthroplasty: Case Series with Minimum Five-Year Follow-Up.

INTRODUCTION: Lateral unicompartmental knee arthroplasty has been shown to be a successful treatment modality for isolated lateral osteoarthritis (OA) of the knee. The reproduction of proper knee kinematics, limb alignment, as well as proper soft tissue balancing and component positioning have been shown to be of the utmost importance for a successful unicompartmental knee arthroplasty (UKA). Robotic assistance has shown to be a reliable tool in order to replicate these factors, as compared to manual instrumentation alone. Recent studies have shown the potential of robotic-assisted surgery in controlling these surgical factors for medial UKA; however, studies assessing outcomes of robotic-assisted lateral UKA (RAUKA) are lacking. Therefore, a retrospective single-center study was performed to assess outcomes of lateral RAUKA. MATERIALS AND METHODS: Patients who underwent lateral RAUKA from a single surgeon at a central institution between January 2008 and June 2017 were identified. All patients received a lateral UKA with a fixed-bearing metal backed onlay tibial component. Patients over the age of 18, with at least a five-year follow-up and a lateral UKA were contacted by phone and asked a series of questions to determine satisfaction and survivorship. Each patient was asked in a "yes" or "no" manner, if they have had their implant revised or reoperated for any reason, and a 5-point Likert scale was used to assess satisfaction. RESULTS: Data was collected from 50 patients (53 knees). Of the patients that responded: 32 (60%) were right knees; 32 (60%) were female, and average follow-up was 7.6 years (5-14 years). Of the 53 knees, one had a revision (98% survivorship). Excluding the revision, 51 (98%) of the included cases were either "very satisfied" or "satisfied" with their surgery. DISCUSSION/CONCLUSIONS: Robotic-arm assisted lateral UKA was found to have high survivorship and a satisfaction rate in patients that had at least a five-year follow-up. In the future, larger prospective comparison studies with longer follow-ups are necessary to adequately compare survivorship and satisfaction rates of robotic-assisted lateral UKA to conventional UKA.

Risk of Venous Thromboemboli, Readmissions, and Costs in Opioid Use Disorder Patients Following Revision Total Knee Arthroplasty.

INTRODUCTION: Opioid use disorder (OUD) patients have an increased risk of venous thromboembolism (VTE), readmissions, and higher costs following primary elective primary total joint arthroplasty, but these risks have not yet been clarified for other arthroplasty surgeries. Thus, the purpose of this study was to investigate whether OUD patients undergoing revision total knee arthroplasty (RTKA) have higher rates of: VTEs, readmissions, and costs of care. MATERIALS AND METHODS: Patients who had a 90-day history of OUD prior to undergoing RTKA were identified and randomly matched to a comparison cohort in a 1:4 ratio by age, sex, Elixhauser-Comorbidity Index (ECI), diabetes mellitus, hyperlipidemia, hypertension, obesity, and tobacco use with a total of 16,851 patients collectively in both groups. The 90-day frequency and odds (OR) of developing VTE, deep vein thrombosis (DVTs), and PEs along with 90-day readmission rates and 90-day costs of care were analyzed. A p-value less than 0.01 was considered statistically significant. RESULTS: OUD patients undergoing RTKA were found to have a higher incidence and odds of VTE (2.91 vs. 1.88; OR: 1.58, p<0.0001) 90 days following RTKA. Compared to the matched cohort, patients who have OUD had a higher incidence and increased risk of lower extremity DVT (2.61 vs. 1.73; OR: 1.52, p=0.0008) and PE (0.97 vs. 55%; OR: 1.74, p=0.007). Furthermore, the likelihood (25.7 vs. 21.4%; OR: 1.26, p<0.0001) of being readmitted within 90 days was higher in OUD patients. Additionally, OUD was associated with significantly higher total global 90-day episode-of-care costs ($19,289.31 ± $17,378.71 vs. $17,292.87 vs. $11,690.61; p<0.0001). CONCLUSION: Patients who have OUD undergoing RTKA have higher rates of thromboembolic complications, readmission rates, and total global 90-day episode-of-care costs. Orthopaedic surgeons should educate OUD patients about these risks and titrate patient opioid consumption through multi-specialty interventions prior to surgery to improve outcomes and reduce costs.

Enhanced Mid-Resection Workflow Technique for Severe Varus Deformity Correction Using Robotic-Arm Assisted Total Knee Arthroplasty.

INTRODUCTION: Robotic technology in total knee arthroplasty has been proven to improve accuracy of component positioning, achieve alignment targets, and balance the knee objectively. However, the utility of robotics in correction of severe varus deformities of the knee has not been investigated in detail. The aim of this paper was to establish the utility and describe the technique of robotic-arm assisted total knee arthroplasty (RA-TKA) in achieving pre-balance in severe varus deformities of the knee. MATERIALS AND METHODS: Among the existing Mako (Stryker, Kalamazoo, Michigan) RA-TKA workflows, pre-resection workflow is limited to knees which can be pre-balanced by component positioning according to functional alignment. Mid-resection workflow (distal femur/tibia first) is reserved for complex cases, whereby the extension gap is balanced first. In our experience, both workflows could not achieve pre-balance in severe varus deformities, necessitating the need to develop a novel technique. The ability of the robot to execute precise bone cuts allows for a provisional postero-medial femoral bone cut in flexion, giving access to remove large inaccessible posterior osteophytes and the tight posterior capsule, thus balancing the knee in extension. The flexion gap is subsequently matched to the extension gap by alterations in axial component positioning. CONCLUSION: This novel "enhanced mid-resection workflow" technique establishes the utility of the RA-TKA in balancing severe varus deformities of the knee. We also propose an algorithm which simplifies and helps surgeons choose between the three workflows to pre-balance knees irrespective of the severity of the varus deformity.

Reasons and Risk Factors for Emergency Department Visits After Primary Total Knee Arthroplasty: An Analysis of 1.3 Million Patients.

BACKGROUND: Well-powered studies investigating the relationship of emergency department (ED) visits and total knee arthroplasty (TKA) are limited. Therefore, the specific aims of this study were to: 1) compare patient demographics of patients who did and did not have an ED visit; and for the visits, identified: 2) leading reasons; and 3) risk factors for ED visits (prearthroplasty/postarthroplasty). METHODS: Patients undergoing primary TKA who had an ED visit within 90 days after their index procedure were identified from a nationwide database. The query yielded 1,364,655 patients who did (n = 5689) and did not have (n = 1,358,966) an ED visit. Baseline demographics such as age, sex, and comorbidity prevalence between the two cohorts; reasons for ED visits; and prearthroplasty and postarthroplasty risk factors were analyzed. Odds ratios (ORs) of ED visits were assessed using multivariate binomial logistic regression analyses. A P-value less than 0.001 was considered statistically significant. RESULTS: Patients who did and did not have ED visits differed with respect to age (P < .0001) and mean Elixhauser Comorbidity Index scores (9 vs 6, P < .0001). Musculoskeletal etiologies were the most common reason for ED visits. Hypertension was the greatest contributor to ED visits prearthroplasty and postarthroplasty. Comorbid conditions associated with ED visits postarthroplasty included peripheral vascular disease (OR: 1.61, P < .0001), coagulopathy (OR: 1.58, P < .0001), and rheumatoid arthritis (OR: 1.56, P < .0001). CONCLUSION: By identifying demographic patterns of patients, reasons, and risk factors, the information found from this study can help identify targets for quality improvement to potentially reduce the incidence of ED visits after primary TKA.

Impact of Postoperative Zolpidem Use on Primary Total Knee Arthroplasty: A Retrospective Matched-Controlled Analysis of a Private Insurance Database.

INTRODUCTION: Zolpidem has gained popularity as a pharmaceutical therapy for insomnia, being the most prescribed hypnotic in the United States today. However, it is associated with increased mortality and morbidity. Literature regarding zolpidem use in the total knee arthroplasty (TKA) population is limited. The aim of the study was to analyze postoperative zolpidem use in the TKA population regarding medical and implant complications, falls, and readmission. METHODS: The study group was queried according to zolpidem use. Controls consisted of patients who underwent primary TKA without a history of hypnotic drug use. Study group patients were matched to controls in a 1:5 ratio by demographics and comorbidities. Results yielded 99,178 study participants and 495,795 controls. Primary endpoints included 90-day medical and implant complications, fall risk, and readmission. Chi-squared test was used to compare categorical variables. Multivariate logistic regression was used to calculate odds (OR) for complications, fall risk, and readmission. A P value less than 0.05 was considered statistically significant. RESULTS: Study group patients had increased odds of medical complications (OR: 1.76, 95% CI: 1.71-1.82, P < .0001) and implant complications (OR: 1.35, 95% CI: 1.23-1.47, P < .0001) compared to controls. Furthermore, patients in the study group were found to have an increased risk of 90- day falls (OR: 1.16, 95% CI: 1.11-1.21, P < .0001). Readmission was similar to controls (5.10% vs 4.84%, P = .12). CONCLUSION: Zolpidem use following primary TKA is associated with the risk of morbidity and falls. The findings are consistent with the literature regarding zolpidem. These findings may affect discussion between orthopedic surgeons and patients in the decision-making process prior to undergoing TKA.

Pigmented Villonodular Synovitis of the Hip in Patients Undergoing Total Hip Arthroplasty: A Retrospective Case-Controlled Analysis.

BACKGROUND: Pigmented villonodular synovitis (PVNS) is a condition affecting larger joints such as the hip and knee. Little is known regarding the impact of PVNS on total hip arthroplasty (THA). Therefore, the aim of this study is to determine if patients with PVNS of the hip undergoing primary THA experience greater (1) in-hospital lengths of stay (LOS); (2) complications; (3) readmission rates; and (4) costs. METHODS: Patients undergoing primary THA for PVNS of the hip from the years 2005 to 2014 were identified using a nationwide claims registry. PVNS patients were matched to a control cohort in a 1:5 ratio by age, gender, and various comorbidities. The query yielded 7440 patients with (n = 1240) and without (n = 6200) PVNS of the hip undergoing primary THA. Endpoints analyzed included LOS, complications, readmission rates, and costs. Multivariate logistic regression was used to determine odds ratios (OR) of developing complications. Welch's t-tests were used to test for significance in LOS and cost between the cohorts. A P-value less than .001 was considered statistically significant. RESULTS: PVNS patients had approximately 8% longer in-hospital LOS (3.8 vs 3.5 days, P = .0006). PVNS patients had greater odds of (OR 1.60, P < .0001) medical and (OR 1.81, P < .0001) implant-related complications. Furthermore, PVNS patients were found to have higher odds (OR 1.84, P < .0001) of 90-day readmissions. PVNS patients also incurred higher day of surgery ($13,119 vs $11,983, P < .0001) and 90-day costs ($17,169 vs $15,097, P < .0001). CONCLUSION: Without controlling for global trends in LOS, complications, readmissions, or costs between 2005 and 2014, the findings of the study suggest that PVNS of the hip is associated with worse outcomes and higher costs following primary THA. The study is useful as orthopedic surgeons can use the study to educate patients of the complications which may occur following their hip surgery.

How to Quantitatively Balance a Total Knee? A Surgical Algorithm to Assure Balance and Control Alignment.

To achieve a balanced total knee, various surgical corrections can be performed, while intra-operative sensors and surgical navigation provide quantitative, patient-specific feedback. To understand the impact of these corrections, this paper evaluates the quantitative impact of both soft tissue releases and bone recuts on knee balance and overall limb alignment. This was achieved by statistically analyzing the alignment and load readings before and after each surgical correction performed on 479 consecutive primary total knees. An average of three surgical corrections were required following the initial bone cuts to achieve a well aligned, balanced total knee. Various surgical corrections, such as an arcuate release or increasing the tibial polyethylene insert thickness, significantly affected the maximum terminal extension. The coronal alignment was significantly impacted by pie-crusting the MCL, adding varus to the tibia, or releasing the arcuate ligament or popliteus tendon. Each surgical correction also had a specific impact on the intra-articular loads in flexion and/or extension. A surgical algorithm is presented that helps achieve a well-balanced knee while maintaining the sagittal and coronal alignment within the desired boundaries. This analysis additionally indicated the significant effect that soft tissue adjustments can have on the limb alignment in both anatomical planes.

Higher Patient Complexities are Associated with Increased Length of Stay, Complications, and Readmissions After Total Hip Arthroplasty.

INTRODUCTION: There is an increased incidence of complex patients undergoing total hip arthroplasty (THA), which demands a rigorous preoperative, intraoperative, and postoperative assessment. It is important how increases in patient complexity impact a variety of patient outcomes. Therefore, the purpose of our study is to determine if a higher Elixhauser Comorbidity Index (ECI), a measure of patient complexity, is correlated with: 1) longer hospital length of stay; 2) increased 90-day medical complications; 3) higher 90-day readmissions; and 4) greater two-year implant-related complications following primary THA. MATERIALS AND METHODS: Patients undergoing primary THA from January 1, 2004 to December 31, 2015 were queried from the Medicare Standard Analytical Files using the International Classification of Disease, ninth revision (ICD-9) procedure code 81.51. The queried patients (387,831) were filtered by ECI scores of 1 to 5. Patients who have ECI scores of 2 to 5 represented the study cohorts and were matched according to age and sex to patients who have the lowest ECI score (ECI of 1). All cohorts were longitudinally followed to assess and compare hospital length of stay, 90-day medical complications, 90-day readmissions, and two-year implant-related complications. We compared odds-ratios (OR), 95% confidence intervals (95% CI), and p-values using logistic regression analyses and Welch's t-tests. RESULTS: Patients who have ECI scores greater than 1 had higher hospital length of stay (p<0.001), 90-day medical complications (p<0.001), 90-day readmissions (p<0.001), and two-year implant-related complications (p<0.001). Patients who have an ECI score of 2 (1.26, 95% CI: 1.20-1.32), ECI of 3 (1.61, 95% CI: 1.53-1.69), ECI of 4 (2.05, 95% CI: 1.95-2.14), and ECI of 5 (2.32, 95% CI: 2.21-2.43) had an increasing trend for readmissions, with higher ECI scores correlating with greater odds of readmission following primary THA. Two-year implant-related complications also showed a similar increasing trend with greater patient complexity. Patients who had an ECI score of 5 (2.54, 95% CI: 2.39-2.69) had more implant-related complications compared to patients who had an ECI score of 2 (1.39, 95% CI:1.31-1.48). CONCLUSION: The results of this study illustrate that a higher Elixhauser-Comorbidity Index is an independent risk factor for longer hospital length of stay, higher 90-day medical complications, greater 90-day readmissions, and increased two-year implant-related complications following primary THA. This study is important as it further defines and heightens awareness of adverse events for complex patients undergoing this procedure. Future studies can examine if these events can potentially be mitigated through reductions in ECI scores prior to surgery and increased incentives for the healthcare team.

Opioid Use Disorder Is Associated with an Increased Risk of Infection after Total Joint Arthroplasty: A Large Database Study.

BACKGROUND: Recent studies have shown that patients with opioid use disorder have impaired immunity. However, few studies with large patient populations have evaluated the risks of surgical site infection (SSI) and prosthetic joint infection (PJI) with opioid use disorder after total joint arthroplasty (TJA), and there is a lack of evidence for revision TJA in particular. QUESTIONS/PURPOSES: Are patients with opioid use disorder who undergo (1) primary THA, (2) primary TKA, (3) revision THA, or (4) revision TKA at a higher risk of experiencing SSIs 90 days after surgery or PJIs 2 years after surgery than those who do not have opioid use disorder? METHODS: All primary and revision TJAs performed between 2005 and 2014 were identified from the Medicare Analytical Files of the PearlDiver Supercomputer using ICD-9 codes. This database is one of the largest nationwide databases; it comprehensively and longitudinally tracks patients based on all insurance claims rather than particular hospital visits, and has a low error rate (estimated at 1.3%). Boolean command operators were used to form a study group of patients with a history of opioid use disorder before surgery. ICD-9 diagnosis codes 304.00 to 304.02 and 305.50 to 305.52 were used to identify patients with opioid use disorder. Study group patients were matched 1:1 to control participants without opioid use disorder undergoing TJA, according to age, sex, and comorbidity burden (Elixhauser comorbidity index [ECI]). The ECI is comprised of 31 different comorbidities and can be used for large administrative databases. The query yielded a study population of 54,332 patients: 14,944 undergoing primary THA (opioid use disorder: n = 7472), 23,680 undergoing primary TKA (opioid use disorder: n = 11,840), 8116 undergoing revision THA (opioid use disorder: n = 4058), and 7592 undergoing revision TKA (opioid use disorder: n = 3796). The primary outcomes analyzed were SSI at 90 days and PJI at 2 years postoperatively, which were identified with ICD-9 codes. Logistic regression analyses were performed to calculate the risk that an infection would develop in a patient with opioid use disorder compared with the matched control patients without opioid use disorder. RESULTS: Patients with opioid use disorder undergoing primary THA had an increased risk of SSI at 90 days (OR 1.85 [95% CI 1.51 to 2.25]; p < 0.001) and PJI at 2 years (OR 1.66 [95% CI 1.42 to 1.93]; p < 0.001). Compared with matched controls, opioid use disorder patients undergoing primary TKA had an increased risk of SSI at 90 days (OR 1.72 [95% CI 1.46 to 2.02]; p < 0.001) and PJI at 2 years (OR 1.31 [95% CI 1.16 to 1.47]; p < 0.001). Similarly, for revision THAs, there was an increase in 90-day SSIs (OR 1.89 [95% CI 1.53 to 2.32]; p < 0.001) and 2-year PJIs (OR 4.24 [95% CI 3.67 to 4.89]; p < 0.001). The same held for revision TKAs for 90-day SSIs (OR 1.88 [95% CI 1.53 to 2.29]; p < 0.001) and 2-year PJIs (OR 4.94 [95% CI 4.24 to 5.76]; p < 0.001). CONCLUSIONS: After accounting for age, sex, and comorbidity burden, these results revealed that patients with opioid use disorder undergoing TJA were at increased risk of having SSIs and PJIs. Based on these findings, healthcare systems and/or administrators should recognize the increased associated PJI and SSI risks in patients with opioid use disorder and enact clinical policies that reflect these associated risks. Additionally, these findings should encourage surgeons to pursue multidisciplinary approaches to help patients reduce their opioid consumption before their arthroplasty procedure. LEVEL OF EVIDENCE: Level III, therapeutic study.

What Are Risk Factors for Infection after Primary or Revision Total Joint Arthroplasty in Patients Older Than 80 Years?

BACKGROUND: Patients older than 80 years of age form an increasing proportion of the patient population undergoing total joint arthroplasty (TJA). With increasing life expectancy and the success of TJA, orthopaedic surgeons are more likely to operate on patients older than 80 years than ever before. Given that most other studies focus on younger populations, only evaluate primary TJA, or limit patient populations to institutional or regional data, we felt a large-database, nationwide analysis of this demographic cohort was warranted, and we wished to consider both primary and revision TJA. QUESTIONS/PURPOSES: In this study, we sought to investigate the risk factors for surgical site infections (SSIs) at 90 days and periprosthetic joint infections (PJIs) at 2 years after surgery in patients aged 80 years and older undergoing (1) primary and (2) revision lower extremity TJA. METHODS: All patients aged 80 years or older who underwent primary or revision TJA between 2005 and 2014 were identified using the Medicare Analytical Files of the PearlDiver Supercomputer using ICD-9 codes. This database is unique in that it is one of the largest nationwide databases, and so it provides a large enough sample size of patients 80 years or older. Additionally, this database provides comprehensive and longitudinal patient data tracking, and a low error rate. Our final cohort consisted of 503,241 patients (TKA: n = 275,717; THA: n = 162,489; revision TKA: n = 28,779; revision THA: n = 36,256). Multivariate logistic regression models were constructed to evaluate the association of risk factors on the incidences of 90-day SSI and 2-year PJI. Variables such as sex, diabetes, BMI, and congestive heart failure, were included in the multivariate regression models. Several high-risk comorbidities as identified by the Charlson and Elixhauser comorbidity indices were selected to construct the models. We performed a Bonferroni-adjusted correction to account for the fact that multiple statistical comparisons were made, with a p value < 0.002 being considered statistically significant. RESULTS: For primary TKA patients, an increased risk of 90-day SSIs was associated with male sex (OR 1.28 [95% CI 1.25 to 1.52]; p < 0.001), BMI greater than 25 k/m (p < 0.001), and other comorbidities. For primary THA patients, an increased risk of 90-day SSIs was associated with patients with obesity (BMI 30-39 kg/m; OR 1.91 [95% CI 1.60 to 2.26]; p < 0.001) and those with morbid obesity (BMI 40-70 kg/m; OR 2.58 [95% CI 1.95 to 3.36]; p < 0.001). For revision TKA patients, an increased risk of SSI was associated with iron-deficiency anemia (OR 1.82 [95% CI 1.37 to 2.28]; p < 0.001). For revision THA patients, electrolyte imbalance (OR 1.48 [95% CI 1.23 to 1.79]; p < 0.001) and iron-deficiency anemia (OR 1.63 [95% CI 1.35 to 1.99]; p < 0.001) were associated with an increased risk of 90-day SSI. Similar associations were noted for PJI in each cohort. CONCLUSIONS: These findings show that in this population, male sex, obesity, hypertension, iron-deficiency anemia, among other high-risk comorbidities are associated with a higher risk of SSIs and PJIs. Based on these findings, orthopaedic surgeons should actively engage in comanagement strategies with internists and other specialists to address modifiable risk factors through practices such as weight management programs, blood pressure reduction, and electrolyte balancing. Furthermore, this data should encourage healthcare systems and policy makers to recognize that this patient demographic is at increased risks for PJI or SSI, and these risks must be considered when negotiating payment bundles. LEVEL OF EVIDENCE: Level III, therapeutic study.

Implant-Related Complications Among Patients With Opioid Use Disorder Following Primary Total Hip Arthroplasty: A Matched-Control Analysis of 42,097 Medicare Patients.

BACKGROUND: Opioid use disorders (OUD) are a major cause of morbidity and mortality. The authors of this study hypothesize that patients who have an OUD will have greater relative risk of implant-related complications, periprosthetic joint infections (PJIs), readmission rates, and will incur greater costs compared to non-opioid use disorder (NUD) patients following primary total hip arthroplasty (THA). METHODS: OUD patients who underwent a THA between 2005 and 2014 were identified and matched to controls in a 1:5 ratio according to age, sex, a comorbidity index, and various medical comorbidities yielding 42,097 patients equally distributed in both cohorts. Pearson's chi-square analyses were used to compare patient demographics. Relative risk (RR) was used to analyze and compare risk of 2-year implant-related complications, 90-day PJIs, and 90-day readmission rates. Welch's t-tests were used to compare day of surgery and 90-day episode-of-care costs between the cohorts. A P value less than .006 was considered statistically significant. RESULTS: OUD patients had higher incidences and risks of implant-related complications (11.99% vs 6.68%; RR, 1.74; P < .001), developing PJIs within 90 days (2.38% vs 1.81%; RR, 1.32; P = .001), and 90-day readmissions (21.49% vs 17.35%; RR, 1.23; P < .001). Additionally, the study demonstrated OUD patients incurred greater day of surgery ($14,384.30 vs $13,150.12, P < .0001) and 90-day costs ($21,183.82 vs $18,709.02, P < .0001) compared to controls. CONCLUSION: After controlling for age, sex, a comorbidity index, and various medical complications, OUD patients are at greater risk to experience implant-related complications, PJIs, readmissions, and have greater costs following primary THA compared to non-OUD patients. This study should help orthopedic surgeons counsel their patients of potential complications which may arise following their primary THA.

Increased Medical Complications, Revisions, In-Hospital Lengths of Stay, and Cost in Patients With Hypogonadism Undergoing Primary Total Knee Arthroplasty.

BACKGROUND: Research regarding the impact of hypogonadism following primary total knee arthroplasty (TKA) is limited. Therefore, the purpose of this study is to investigate whether patients with hypogonadism undergoing primary TKA are at increased odds of (1) medical complications, (2) revisions, (3) in-hospital lengths of stay (LOSs), and (4) cost of care. METHODS: A Humana patient population consisting of 8 million lives was retrospectively analyzed from 2007 to 2017 using International Classification of Disease, 9th Revision codes. Patients were filtered by male gender and patients with hypogonadism were matched to controls in a 1:4 ratio according to age and medical comorbidities. The query yielded 8393 patients with (n = 1681) and without (6712) hypogonadism undergoing primary TKA. Primary outcomes analyzed included medical complications, revision rates, in-hospital LOS, and cost of care. Logistic regression analysis was used to calculate odds ratios (OR) of 90-day medical complications and 2-year revisions. Welch's t-test was used to test for significance in LOS and cost of care between cohorts. A P-value less than .05 was considered statistically significant. RESULTS: Hypogonadal patients undergoing primary TKA were found to have increased incidence and odds (9.45% vs 4.67%; OR 2.12, P < .0001) of developing 90-day medical complications. Hypogonadal patients undergoing primary TKA were found to have a greater incidence and odds (3.99% vs 2.80%; OR 1.89, P < .0001) of 2-year revisions. Hypogonadal patients had a 6.11% longer LOS (3.47 vs 3.27 days, P = .02) compared to controls, and incurred greater 90-day costs ($15,564.31 vs $14,856.69, P = .018) compared to controls. CONCLUSION: This analysis of over 1600 patients demonstrates that patients with hypogonadism undergoing primary TKA have greater odds of postoperative medical complications, revisions, increased LOS, and cost of care.

Comparison Study of Patient Demographics, Risk Factors, and Lengths of Stay for Postoperative Ileus After Primary Total Knee Arthroplasty.

BACKGROUND: Postoperative ileus is a potential complication after orthopedic surgery, which has not been well studied after total knee arthroplasty (TKA). The aims of this study were to analyze rates of postoperative ileus; patient demographic profiles; in-hospital lengths of stay (LOS); and patient-related risk factors for postoperative ileus after primary TKA. METHODS: A query was performed from January 1, 2005 to March 31, 2014 using the Medicare Standard Analytical Files. Patients who underwent primary TKA and developed postoperative ileus within 3 days after their index procedure were identified. Patients who did not develop ileus represented controls. Primary outcomes analyzed and compared included patient demographics, risk factors, and in-hospital LOS. A P value less than .05 was considered statistically significant. RESULTS: Ileus patients were older, more likely to be male, and had higher Elixhauser-Comorbidity Index scores (8 vs 6; P < .0001) compared with controls. Male patients (odds ratio [OR], 2.12; P < .0001), patients with preoperative electrolyte/fluid imbalance (OR, 3.40; P < .001), patients older than 70 years (OR, 1.62-2.33; P < .015), and body mass indices greater than 30 kg/m2 (OR, 1.79-2.00; P < .001) were at the greatest risk of developing ileus. In addition, ileus patients had significantly longer in-hospital LOS (5.42 vs 3.22 days; P < .001). CONCLUSION: The study demonstrated differences in patient demographics, patient-related risk factors, and an increased in-hospital LOS for ileus patients after primary TKA. The study is important as it can allow orthopedists to properly identify and optimize patients with certain risk factors to potentially mitigate this adverse event from occurring.

Chronic Obstructive Pulmonary Disease Is Associated With Higher Rates of Venous Thromboemboli Following Primary Total Knee Arthroplasty.

BACKGROUND: There is discordance in the literature regarding the presence of chronic obstructive pulmonary disease (COPD) and the development of venous thromboemboli (VTEs). Therefore, the purpose of this study is to determine whether COPD patients undergoing primary total knee arthroplasty (TKA) have higher rates of (1) in-hospital lengths of stay (LOS); (2) readmissions; (3) VTEs; and (4) costs of care. METHODS: COPD patients undergoing primary TKA were identified and matched to controls in a 1:5 ratio by age, gender, and medical comorbidities. Patients with a history of VTEs or hypercoagulable states were excluded. The query yielded 211,378 patients in the study (n = 35,230) and control (n = 176,148) cohorts. Outcomes analyzed included in-hospital LOS, readmission rates, VTEs, and costs of care. A P-value less than .01 was considered statistically significant. RESULTS: COPD patients were found to have significantly longer in-hospital LOS (4 vs 3 days, P < .0001). Study group patients were also found to have significantly higher incidence and odds ratio (OR) of readmission rates (20.9% vs 16.3%; OR 1.36, P < .0001) and VTEs (1.75 vs .93; OR 1.18, P < .0001). Additionally, the study demonstrated that COPD patients incurred higher 90-day episode-of-care costs ($15,626.85 vs $14,471.29, P < .0001). CONCLUSION: After adjusting for confounding variables, our study found an association between COPD and higher rates of developing VTEs following primary TKA. The study can be used by orthopedic surgeons to adequately counsel and educate these patients of the potential complications which may arise following their TKA.