Clinical applications of robotic surgery platforms: a comprehensive review.

Robotic surgery has expanded globally across various medical specialties since its inception more than 20 years ago. Accompanying this expansion were significant technological improvements, providing tremendous benefits to patients and allowing the surgeon to perform with more precision and accuracy. This review lists some of the different types of platforms available for use in various clinical applications. We performed a literature review of PubMed and Web of Science databases in May 2023, searching for all available articles describing surgical robotic platforms from January 2000 (the year of the first approved surgical robot, da Vinci® System, by Intuitive Surgical) until May 1st, 2023. All retrieved robotic platforms were then divided according to their clinical application into four distinct groups: soft tissue robotic platforms, orthopedic robotic platforms, neurosurgery and spine platforms, and endoluminal robotic platforms. Robotic surgical technology has undergone a rapid expansion over the last few years. Currently, multiple robotic platforms with specialty-specific applications are entering the market. Many of the fields of surgery are now embracing robotic surgical technology. We review some of the most important systems in clinical practice at this time.

Immediate Postoperative Zolpidem Use Increases Risk of Falls and Implant Complication Rates Following Total Hip Arthroplasty: A Retrospective Case-Control Analysis.

BACKGROUND: Zolpidem is the most widely used hypnotic in the United States and has known side effects. However, the morbidity of zolpidem use following total hip arthroplasty (THA) is not well-defined. Thus, the aim of this study was to assess the effects that zolpidem use has on medical and implant complications, falls, lengths of stay, and medical utilizations following THA. METHODS: A retrospective query of a nationwide insurance claims database was conducted from 2010 to 2020. All cases of THA and hypnotic use were identified using procedural and national drug codes. Patients who were prescribed zolpidem within 90 days of surgery were matched to hypnotic naive patients 1:5 based on demographic and comorbidity profiles. The 90-day medical complications, falls, fragility fractures, costs, and readmission rates, as well as 2-year implant complications were compared between cohorts. A total of 50,328 zolpidem patients were matched to 251,286 hypnotic naive patients. RESULTS: The zolpidem group had significantly higher rates of medical complications, falls, and fragility fractures when compared to the hypnotic-naive group. The zolpidem group had significantly higher rates of dislocation, mechanical loosening, and periprosthetic fracture. Likewise, healthcare utilization was significantly greater in the zolpidem group. CONCLUSION: Zolpidem use following THA is associated with significant risk of medical and implant complications, as well as fall risks, increased costs, lengths of stay, and readmissions. The findings of this study may affect discussions between orthopaedic surgeons and their patients on the benefits of sleep quality in their recovery versus the incurred risks of zolpidem use. LEVEL OF EVIDENCE: III, retrospective case-control study.

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.

Accuracy of Intraoperative Mechanical Axis Alignment to Long-Leg Radiographs following Robotic-Arm-Assisted Unicompartmental Knee Arthroplasty.

Improper alignment and implant positioning following unicompartmental knee arthroplasty (UKA) has been shown to lead to postoperative pain and increase the incidence of revision procedures. The use of robotic-arm assistance for UKA (RAUKA) has become an area of interest to help overcome these challenges. The accuracy of intraoperative alignment compared with standing long-leg X-rays postoperatively following medial RAUKA has been in question. Therefore, the purpose of this study was to (1) determine final mean intraoperative coronal alignment in extension utilizing an image based intraoperative navigation system, and (2) compare final intraoperative alignment to 6-week weight-bearing (WB) long-leg X-rays. Patients who underwent RAUKA for medial compartmental osteoarthritis were identified from January 1, 2018, to August 31, 2019, through our institution's joint registry. The query yielded 136 (72 right and 64 left) patients with a mean age of 72.02 years and mean body mass index (BMI) of 28.65 kg/m2 who underwent RAUKA. Final intraoperative alignment was compared with WB long leg X-rays 6 weeks postoperatively by measuring the mechanical alignment. Statistical analysis was primarily descriptive. Pearson's correlation coefficient was used to determine the relationship between intraoperative alignment to 6-week alignment. A p-value of <0.05 was considered statistically significant. Mean intraoperative coronal alignment after resections and trialing was 4.39 varus ± 2.40 degrees for the right knee, and 4.81 varus ± 2.29 degrees for the left knee. WB long-leg X-rays 6 weeks postoperatively demonstrated mechanical axis alignment for the right and left knees to be 3.01 varus ± 2.10 and 3.7 varus ± 2.38 degrees, respectively. This resulted in a change in alignment of 1.36 ± 1.76 and 1.12 ± 1.84 degrees for the right and left knees, respectively (p < 0.05). Pearson's correlation coefficient demonstrated a correlation of 0.69 between intraoperative to long-leg-X-ray alignment. RAUKA demonstrates excellent consistency when comparing postoperative WB long-leg X-rays to final intraoperative image-based non-WB alignment.

Do Patients with Paget's Disease Have Worse Outcomes following Primary Total Knee Arthroplasty?

Well-powered studies evaluating the effects of Paget's disease on patient outcomes following primary total knee arthroplasty (TKA) are limited. The objective of this study was to determine whether Paget's disease patients undergoing primary TKA have higher rates of complications. A query of an administrative database was performed identifying Paget's disease patients undergoing primary TKA as the study cohort. Patients who did not have Paget's disease served as a matching cohort. Study group patients were matched in a 1:5 ratio by age, sex, and comorbidities. The query yielded 34,284 patients in the study (n = 5,714) and matched (n = 28,570) cohorts. Outcomes analyzed included length of stay (LOS), costs of care, 90-day medical and surgical complications, and 2-year implant-related complications. Multivariate logistic regression analyses were used to calculate the odds ratios (ORs) of complications. Paget's disease patients undergoing primary TKA were found to have significantly longer in-hospital LOS (4 vs. 3 days, p < 0.0001). Study group patients incurred significantly higher 90-day episode-of-care costs ($15,124.55 vs. $14,610.01, p < 0.0001). Additionally, Paget's disease patients were found to have higher incidences and odds of medical/surgical (25.93 vs. 13.58%; OR: 1.64, p < 0.0001) and implant-related complications (8.97 vs. 5.02%; OR: 1.71, p < 0.0001). Specifically, Paget's disease patients were more likely to have periprosthetic fractures, mechanical loosening, and revision TKAs (p < 0.0001). This study demonstrated that Paget's disease was associated with longer in-hospital LOS, increased costs, and higher rates of complications. The study can be utilized by physicians to adequately educate patients with Paget's disease concerning potential complications following their primary TKA.

The association of iron deficiency anemia and perioperative complications following revision total knee arthroplasty.

BACKGROUND: Recent studies show an increase in the prevalence of iron deficiency anemia (IDA) worldwide and a concomitant rise in the number of revision total knee arthroplasty (RTKA). The literature evaluating the association between IDA and perioperative outcomes following RTKA are limited. Therefore, the purpose of this study was to determine whether IDA patients undergoing RTKA have higher rates of (1) in-hospital lengths of stay (LOS), (2) complications; and (3) costs. METHODS: Using International Classification of Disease, Ninth Revision (ICD-9) and Current Procedural Terminology (CPT), a retrospective query was performed from January 1st, 2005 to March 31st, 2014. The inclusion criteria consisted of those patients who have IDA undergoing RTKA. Study group patients were 1:5 ratio matched to a comparison cohort by age, sex, and various comorbidities: coronary artery disease, chronic obstructive pulmonary disease, diabetes mellitus, hyperlipidemia, hypertension, obesity, and tobacco use, yielding a total of 106,534 patients within the study (n = 17,784) and control (n = 88,750) cohorts. Outcomes assessed included: in-hospital LOS, costs of care, and medical complications. Multivariate Logistic regression analyses were used to calculate the odds-ratios (OR) and respective 95% confidence intervals (95%CI). Welch's t-tests were used to compare in-hospital LOS and costs of care. Following Bonferroni-correction, a P-value less than 0.001 was considered statistically significant. RESULTS: IDA patients undergoing RTKA were found to have significantly higher in-hospital LOS (4-days vs. 3-days, P < 0.0001). Additionally, IDA patients were found to have significantly higher odds (OR) of medical complications (OR: 5.29, P < 0.0001) such as: pneumonia (OR: 6.86, P < 0.0001), respiratory failures (OR: 5.95, P < 0.0001), myocardial infarctions (OR: 4.31, P < 0.0001) and other complications. Furthermore, IDA patients incurred significantly higher day of surgery ($16,976.01 vs. $14,515.81, P < 0.0001) and 90-day costs ($22,548.71 vs. $16,819.15, P < 0.0001). CONCLUSION: The study demonstrated IDA patients undergoing RTKA have higher rates of in-hospital LOS, costs of care, and medical complications. Orthopedic surgeons and other healthcare professionals can use this information to adequately educate these patients of the potential complications following their procedure.

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.

Comparative Analysis on the Effects of Sarcopenia following Primary Total Knee Arthroplasty: A Retrospective Matched-Control Analysis.

Despite the high incidence of sarcopenia in the orthopaedic community, studies evaluating the influence of sarcopenia following primary total knee arthroplasty (TKA) are limited. Therefore, the purpose of this study is to determine if sarcopenic patients undergoing primary TKA have higher rates of (1) in-hospital lengths of stay (LOS); (2) medical complications; (3) implant-related complications; (4) fall risk; (5) lower extremity fracture risk; and (6) costs of care. Sarcopenia patients were matched to controls in a 1:5 ratio according to age, sex, and medical comorbidities. The query yielded 90,438 patients with (n = 15,073) and without (n = 75,365) sarcopenia undergoing primary TKA. Primary outcomes analyzed included: in-hospital LOS, 90-day medical complications, 2-year implant-related complications, fall risk, lower extremity fracture risk, and costs of care. A p-value of less than 0.05 was considered statistically significant. Patients with sarcopenia undergoing primary TKA had greater in-hospital LOS (4 vs. 3 days, p < 0.0001). Sarcopenic patients were also found to have increased incidence and odds of 90-day medical complications (2.9 vs. 1.1%; odds ratio [OR] = 2.83, p < 0.0001), falls (0.9 vs. 0.3%; OR = 3.54, p < 0.0001), lower extremity fractures (1.0 vs. 0.2%; OR = 5.54, p < 0.0001), and reoperation (0.9 vs. 0.5%; OR = 1.87, p < 0.0001). Additionally, sarcopenic patients had greater 2-year implant-related complications (4.3 vs. 2.4%; OR = 1.80, p < 0.0001), as well as day of surgery ($52,900 vs. 48,248, p < 0.0001), and 90-day ($68,303 vs. $57,671, p < 0.0001) costs compared with controls. This analysis of over 90,000 patients demonstrates that patients with sarcopenia undergoing primary TKA have greater in-hospital LOS, increased odds of 90-day medical complications, falls, lower extremity fractures, and reoperations. Additionally, sarcopenia was associated with greater 2-year implant-related complications, day of surgery costs, and 90-day costs. The study is useful as it can allow orthopaedic surgeons to properly educate these patients of the potential complications which may occur following their surgery.

Gout As a Predictor of Total Knee Arthroplasty Outcomes and Costs.

Gout is the most common inflammatory arthritis and affects approximately 4% of the U.S. population. As the prevalence of gout and the number of total knee arthroplasties (TKAs) performed continue to increase, the literature on TKA in patients with gout remains scant. The purpose of this study was to evaluate the outcomes of patients with gout following TKA at a population level, that is, how patient with gout fair after TKA. We hypothesized that patients with gout have higher rates of complications and higher costs compared with controls. A case-control study was designed to evaluate two cohorts of Medicare patients who underwent TKA whose only distinguishing feature was the presence or absence of gout. Matching was performed to decrease confounding at a 1:1 ratio based on age, gender, and Charlson comorbidity index (CCI), (10-year survival predictor). The Medicare standard analytical files were queried through International Classification of Disease and current procedural terminology codes. A total of 15,238 patients were evaluated with 7,619 in each cohort. There were no age, gender, or CCI differences and 57.4% were females. Day of surgery and 90-day post-surgery costs were both significantly greater in those with gout (p < 0.001 for both). Multivariate analysis revealed that gout patients had increased odds of infection (odds ratio [OR] 1.229, p = 0.019), cardiac arrest (OR 1.354, p = 0.002), pneumonia (OR 1.161, p < 0.001), hematoma (OR 1.204, p = 0.002), and development of capsulitis (OR 1.208, p = 0.012). Nonetheless these patients had a decreased risk of pulmonary emboli (OR 0.835, p = 0.016). Our results support our hypothesis that patients with gout have higher rates of postoperative complications and increased day of surgery and 90-day costs of care after TKA. Given the high prevalence of gout in the United States, additional study on the utility of preoperative gout optimization for TKA patients is warranted. The level of evidence of this study is III, and it is a retrospective case-control study.

Patients With Opioid Use Disorder Have Increased Readmission Rates, Emergency Room Visits, and Costs Following a Hallux Valgus Procedure.

BACKGROUND: Patients with a history of opioid use disorder (OUD) tend to have more complications, higher readmission rates, and increased costs following orthopaedic procedures. This study evaluated patients undergoing hallux valgus correction for their odds of increased (1) readmission rates, (2) emergency room (ER) visits, and (3) costs. METHODS: Patients undergoing hallux valgus corrections with OUD history were identified using a national Medicare administrative claims database of approximately 24 million orthopaedic surgery patients. OUD patients were matched to non-opioid use disorder (NUD) patients in a 1:4 ratio by age, sex, Elixhauser-Comorbidity Index (ECI), diabetes mellitus, hyperlipidemia, hypertension, and tobacco use. The query yielded 6318 patients (OUD = 1276; NUD = 5042) who underwent a hallux valgus correction. Primary outcomes analyzed included odds of 90-day readmission rates, 30-day ER visits, and 90-day episode-of-care costs. Demographics, odds ratios (ORs), ECI, and cost were assessed as appropriate using a Pearson χ2 test, logistic regression, and a t test. A P value <.05 was considered statistically significant. RESULTS: There were no significant differences in demographics between OUD and NUD patients. OUD patients had higher incidence and odds of 90-day readmission (9.56% vs 6.04%; OR = 1.55; P < .001) and 30-day ER visits (0.86% vs 0.35%; OR = 2.42; P = .021) and incurred greater 90-day episode-of-care costs ($7208.28 vs $6134.75; P < .001) compared with NUD patient controls. CONCLUSION: The study demonstrates the possible influence of OUD on higher odds of readmission, ER visits, and costs following a hallux valgus correction. LEVELS OF EVIDENCE: Level III: Retrospective cohort study.

Impact of Biological Sex on Complications, Lengths of Stay, Readmission Rates, and Costs of Care Following Primary Total Knee Arthroplasty.

The impact of gender on total knee arthroplasty (TKA) postoperative complications, readmission rates, and costs of care has not been often evaluated. Therefore, the purpose of this study was to investigate which sex had higher rates of: (1) medical complications; (2) implant complications; (3) lengths of stay (LOSs); (4) readmission rates; and (5) costs after TKA. A query was performed using an administrative claims database from January 1, 2005, to March 31, 2015. Patients who had TKAs were identified using International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes. Males and females were filtered separately and matched according to age and various medical comorbidities leading to 1,590,626 patients equally distributed. Primary outcomes analyzed included 90-day medical complications, LOSs, 90-day readmission rates, in addition to day of surgery and total global 90-day episode of care costs. Pearson's chi-square analyses were used to compare medical complications and readmission rates. Welch's t-tests were used to test for significance in matching outcomes and costs. A p-value of less than 0.01 was considered statistically significant. Males had a smaller risk of complications than women (1.35 vs. 1.40%, p < 0.006) and higher rates of implant-related complications (2.28 vs. 1.99%, p < 0.0001). Mean LOSs were lower for males: 3.16 versus 3.34 days (p < 0.0001). The 90-day readmission rates were higher in men (9.67 vs. 8.12%, p < 0.0001). This study demonstrated that males undergoing primary TKA have lower medical complications and shorter LOSs then their female counterparts. However, males have higher implant-related complications, readmission rates, and costs of care.

Accuracy of Measuring Knee Flexion after TKA through Wearable IMU Sensors.

Wearable sensors have the potential to facilitate remote monitoring for patients recovering from knee replacement surgery. Using IMU sensors attached to the patients' leg, knee flexion can be monitored while the patients are recovering in their home environment. Ideally, these flexion angle measurements will have an accuracy and repeatability at least on par with current clinical standards. To validate the clinical accuracy of a two-sensor IMU system, knee flexion angles were measured in eight subjects post-TKA and compared with other in-clinic angle measurement techniques. These sensors are aligned to the patients' anatomy by taking a pose resting their operated leg on a box; an initial goniometer measurement defines the patients' knee flexion while taking that pose. The repeatability and accuracy of the system was subsequently evaluated by comparing knee flexion angles against goniometer readings and markerless optical motion capture data. The alignment pose was repeatable with a mean absolute error of 1.6 degrees. The sensor accuracy through the range of motion had a mean absolute error of 2.6 degrees. In conclusion, the presented sensor system facilitates a repeatable and accurate measurement of the knee flexion, holding the potential for effective remote monitoring of patients recovering from knee replacement surgery.

Nationwide analysis on the impact of peripheral vascular disease following primary total knee arthroplasty: A matched-control analysis.

BACKGROUND: As the prevalence of peripheral vascular disease (PVD) continues to increase nationwide, studies demonstrating its effects following primary total knee arthroplasty (TKA) are limited. Therefore, the purpose of this study was to evaluate whether patients with PVD have higher rates of: 1) in-hospital lengths of stay (LOS); 2) readmissions; 3) medical complications; 4) implant-related complications; and 5) costs of care. METHODS: Using a nationwide database, patients with PVD undergoing primary TKA were identified and matched to controls in a 1:5 ratio by age, sex, and medical comorbidities. The query yielded 1,547,092 between the cohorts. Outcomes analyzed included: in-hospital LOS, readmission rates, complications, and costs of care. A p-value less than 0.004 was considered statistically significant. RESULTS: PVD patients had significantly longer in-hospital LOS (4-days vs. 3-days, p < 0.0001). Additionally, the study cohort had a higher incidence and odds (OR) of readmissions (20.5 vs. 15.2%; OR: 1.43, 95% CI: 1.42-1.45, p < 0.0001), medical complications (2.46 vs. 1.32%; OR: 1.88, CI: 1.83-1.94, p < 0.0001), and implant-related complications (3.82 vs. 2.18%; OR: 1.78, CI: 1.26-1.58, p < 0.0001). Additionally, the study found patients with PVD had higher day of surgery (p < 0.0001) and 90-day costs of care (p < 0.0001). CONCLUSIONS: After adjusting for confounding variables the results of the study show patients with PVD undergoing primary TKA have longer in-hospital LOS; in addition to higher rates of complications, readmissions, and costs of care. The study can be utilized by orthopaedists to adequately counsel patients of the potential complications following their procedure.

Robotic-Assisted Lateral Unicompartmental Knee Arthroplasty in a Patient With Nail-Patella Syndrome.

A 59-year-old woman with nail patella syndrome (NPS) presented with progressive and severe right knee pain for the past 3 years. Imaging demonstrated laterally dislocated patella, with asymmetric femoral trochlea, and advanced lateral compartment arthritis. The patient underwent robotic-assisted lateral unicompartmental knee arthroplasty (RAUKA). The patient saw marked improvements in patient-reported outcome measurements from her initial visit to the last follow-up visit. While treatment of knee osteoarthritis in patients with NPS can be difficult, especially with attempts of patellar realignment, we present a case of a patient who underwent RAUKA, with sustained improvements in patient outcomes and range of motion, at the 2-year follow-up visit. This study is the first of its kind to demonstrate the use of a novel technology in a rare condition.

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.

Does Increasing Patient Complexity Have an Effect on Medical Outcomes and Lengths-of-Stay after Total Knee Arthroplasty?

A greater number of medically complex patients with multiple comorbidities are now more readily considered for total knee arthroplasty (TKA). Therefore, the purpose of this study was to determine whether comorbidity burden, measured with the Elixhauser Comorbidity Index (ECI), correlated with 90-day medical complications and longer in-hospital lengths-of-stay (LOS) in TKA patients. The PearlDiver supercomputer was queried for all primary TKA patients in the Medicare Standard Analytic Files from 2005 to 2014 using International Classification of Disease, 9th edition codes. Patients were included based on ECI scores, ranging from 1 to 5. ECI 1 patients served as the control cohort, while ECI 2, 3, 4, and 5 patients were considered study cohorts. Each study cohort was matched based on age and gender to the control cohort, resulting in a total of 715,398 patients included for analysis (ECI 1, n = 144,072; ECI 2, n = 144,072; ECI 3, n = 144,072; ECI 4, n = 144,072; ECI 5, n = 139,110). Logistic regression analyses were performed to compare 90-day medical complications and Welch's t-tests were performed to compare LOS between the cohorts. Patients with higher ECI scores were more likely to develop medical complications and have longer LOS compared with matched patients in the control cohort. Compared with matched ECI 1 patients, patients with ECI scores of 2 (odds ratio [OR]: 1.19, 95% confidence interval [CI]: 1.14-1.24), 3 (OR: 1.27, 95% CI: 1.21-1.32), 4 (OR: 1.32, 95% CI: 1.27-1.38), and 5 (OR: 1.33, 95% CI: 1.27-1.39) were significantly more likely to develop 90-day medical complications. Additionally, the mean LOS of patients in the ECI 2 (2.59 ± 1.49 vs. 2.73 ± 1.52 days), ECI 3 (2.59 ± 1.49 vs. 2.88 ± 1.51 days; p < 0.001), ECI 4 (2.59 ± 1.49 vs. 3.01 ± 1.56 days; p < 0.001), and ECI 5 (2.61 ± 1.49 vs. 3.14 ± 1.61 days; p < 0.001) groups were significantly longer than the mean LOS in the control ECI 1 group. In an increasingly complex patient population, associations between comorbidities and outcomes after TKA procedures can guide providers on how to modify their pre- and postoperative care. These results demonstrate that higher ECI scores are associated with a greater likelihood of 90-day medical complications and longer in-hospital LOS.

Cost Analysis of Medicare Patients with Varying Complexities Who Underwent Total Knee Arthroplasty.

The effort to reduce overall healthcare costs may affect more complex patients, as their pre- and postoperative care can be substantially involved. Therefore, the purpose of this study was to use a large nationwide insurance database to compare (1) costs, (2) reimbursements, and (3) net losses of 90-day episodes of care (EOC) for total knee arthroplasty (TKA) patients according to Elixhauser's Comorbidity Index (ECI) scores. All TKAs performed between 2005 and 2014 in the Medicare Standard Analytic Files were extracted from the database and stratified based on ECI scores, ranging from 1 to 5. ECI 1 patients served as the control cohort, while ECI 2, 3, 4, and 5 patients were considered study cohorts. Each study cohort and control cohort were matched based on age and sex, resulting in a total of 715,398 patients included for analysis. Total EOC costs, reimbursements, and total net losses (defined as total EOC costs minus total EOC reimbursements) were compared between the cohorts. Overall, total EOC costs increased with ECI. For example, compared with the matched ECI 1 cohorts, the total EOC costs for ECI 5 patients ($56,589.19 vs. $51,747.54) were significantly greater (p < 0.01). Although reimbursements increased with increasing ECI, so did net losses. The net losses for ECI 5 patients were greater than that for ECI 1 patients ($42,309.39 vs. $40,007.82). The bundled payments for care improvement (BPCI) and comprehensive care for joint replacement (CJR) are alternative payment models that might de-incentivize treatment of more complex patients. Our study found that despite increasing reimbursements, overall costs, and therefore net losses, were greater for more complex patients with higher ECI scores.

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.

Comparison of Patient Demographics and Utilization Trends of Robotic-Assisted and Non-Robotic-Assisted Unicompartmental Knee Arthroplasty.

Robotic-assisted unicompartmental knee arthroplasty (RAUKA) is an emerging area of interest. The purpose of this study was to compare (1) different patient demographic profiles; (2) annual primary and revision utilization rates; (3) risk factors for revision procedures; and (4) survivorship between RAUKA and manual UKA (MUKA). Using the PearlDiver database, patients who underwent RAUKA or MUKA between 2005 and 2014 within the Medicare database were identified, yielding a total of 35,061 patients (RAUKA = 13,617; manual = 21,444). Patient demographics (age, gender, comorbidities, Charlson-Comorbidity Index, and geographic region) were compared between cohorts. Annual primary and revision utilization rates as well as risk factors for revision procedures were also compared. Kaplan-Meier survivorship was also calculated. The Pearson χ2 test was used to test for significance in patient demographics, whereas the Welch t-test was used to compare the incidence of revisions as well as the revision burden (proportion of revisions to total sum of primary and revision procedures). Multivariate binomial logistic regression analysis was performed to compare risk factors for revision procedures. There were statistically significant differences in RAUKA versus MUKA patients with respect to age (p < 0.001), gender (p < 0.001), and region (p < 0.001). RAUKA procedures performed increased over 12-fold compared with manual, which increased only 4.5-fold. RAUKA procedures had significantly lower revision incidence (0.99 vs. 4.24%, p = 0.003) and revision burden (0.91 vs. 4.23%, p = 0.005) compared with manuals. For patients undergoing RAUKA, normal (19-24 kg/m2) and obese (30-39 kg/m2) body mass index (p < 0.05), congestive heart failure (p = 0.004), hypothyroidism (p < 0.001), opioid dependency (p = 0.002), and rheumatoid arthritis (p < 0.001) were risk factors for a revision procedure. Kaplan-Meier survival curve 3 years following the index procedure to all-cause revisions demonstrated that RAUKA patients maintained nearly 100% survivorship compared with manual patients who had 97.5% survivorship. The data demonstrate increased utilization of RAUKA in the United States. The current data indicated that RAUKA has significantly lower revision rates and improved survivorship compared with patients undergoing non-RAUKA within Medicare patients.

An Economic Evaluation of Over 200,000 Revision Total Hip Arthroplasties: Is the Current Model Sustainable?

INTRODUCTION: Revision total hip arthroplasties (rTHAs) are typically more complicated than primaries and may have a greater economic burden. To date, the current economic model supporting these procedures has not been evaluated. Therefore, the purpose of this study was to determine the 10-year temporal changes in charges, reimbursement rates, and net losses in patients undergoing an rTHA utilizing a large, nationwide database. MATERIALS AND METHODS: A query was performed from 2005 to 2014 to identify patients who underwent rTHA. Analyzed outcomes included trends in costs of care, reimbursement rates, and net losses per annum within the last 10 years. Charges are defined as those by the provider to the insurance company, whereas, reimbursements were those payments received from the insurance company. Net losses were calculated as the difference in charges from reimbursement rates. RESULTS: Total charges increased from $1,119,725,881 in 2005 to $2,066,842,547 in 2014. Total reimbursements increased from $287,461,852 in 2005 to $478,430,569 in 2014. Per patient charges increased 67.4% from 2005 to 2014 and from $51,963.18 in 2005 to $86,791.07 in 2014. There was an increase in reimbursement per patient of 61.4% from $12,450.70 in 2005 to $20,090.31 in 2014. Net losses increased 68.80%, from $39,512.48 to $66,700.76 from 2005 to 2014. CONCLUSION: This study indicates substantial increases in charges and reimbursements over a 10-year period for patients undergoing rTHA. However, reimbursement increased at a lower rate than that of charges, resulting in major net losses. This study highlights the need to reevaluate the economic models behind rTHA for longer-term sustainment.