Search

Chronic refractory pain after total joint replacement is debilitating and a source of dissatisfaction for patients. The management of pain following total joint replacement varies during the acute postoperative period compared to the 3 months postoperative at which point the pain is considered chronic pain. Acute postoperative pain relief programs have seen promising results with multimodal pain control through the use of combinations of opioids, acetaminophen, nonsteroidal anti-inflammatory drugs, gabapentinoids and ketamine. The addition of regional blocks to the multimodal regimen has improved acute postoperative pain control following total joint replacements. On the other hand, chronic pain can be successfully managed with options including genicular nerve radioablation therapy (GN-RFA), neuromuscular electrical stimulation (NMES), transcutaneous electrical nerve stimulation (TENS), and peripheral subcutaneous field stimulation (PSFS). While there is still minimal data on chronic pain relief regimens, meta-analyses and case reports have demonstrated the effectiveness and promising outcomes. This paper aims to evaluate the current medications and treatment options for managing refractory pain following TJA.

The aim of this study was to track the annual rates and trends of overall, deep, and superficial surgical site infections (SSIs) following total knee arthroplasty using the most recent results from a large and nationwide database. A total of 197,192 cases were performed between 2012 and 2016 from a nationwide database stratified into years and based on superficial and/or deep SSIs. Cohorts were analyzed individually and then combined to evaluate overall SSI rates. The infection incidence for each year was calculated. After a 6-year correlation and trends analysis, univariate analyses were performed to compare the most recent year, 2016, with each of the preceding 4 years. Overall, there was a downward trend in overall SSI rates over the study period (2012–2016, with the lowest rate occurring in the most recent year, 2016 [0.11%]). Additionally, there was a decreasing trend for superficial SSI, with the lowest superficial SSI incidence occurring in 2016 (0.47%) and the greatest incidence occurring in 2012 (0.53%). An overall trend of decreasing SSI rates was observed nationwide over the 5-year period evaluated. A similar decreasing trend was also noted specifically for deep SSI rates, which can be potentially more complicated to manage, and result in decreased implant survivorship. The down trending SSI rates observed give potential credence to the value for newer and developing SSI preventative therapies as well as improved medical and surgical patient management. Nevertheless, there is still room for improvement, and continued efforts are needed to further lower SSIs after total knee arthroplasty.

Background: The direct anterior approach (DAA) used for primary total hip arthroplasty has been shown to improve early postoperative outcomes, but prior studies have identified a marked learning curve for surgeons transitioning to this approach. However, these studies do not capture surgeons with postgraduate fellowship training in DAA. Therefore, the purpose of this study was to evaluate the learning curve by comparing perioperative outcomes for the first 100 to latter 100 cases and first 50 to final 50 cases. Methods: The first 200 consecutive primary total hip arthroplasties performed by a single surgeon were prospectively followed up for up to 2 years postoperatively. Data on demographic and perioperative factors, 90-day readmissions, and short- and long-term complications were collected. Radiographic outcomes included acetabular cup anteversion and abduction measurements. Logistic regressions were used to calculate odds ratios and confidence intervals for surgical time greater than 2 hours. Results: The first 100 and second 100 cases had significant differences in operative times (118.1 vs 110.4 minutes, P = .009), acetabular abduction (38.3 vs 35.5 degrees, P = .001) and anteversion (13.5 vs 15.1 degrees, P = .009), and incidence of neuropraxia (41 vs 9%, P < .001). Estimated blood loss, transfusions, discharge disposition, length of stay, readmission, and other complications had no statistical significance between the first and second 100 cases. The first 50 cases had higher odds of surgical time greater than 2 hours (odds ratio = 5.2, 95% confidence interval = 1.84-14.75, P = .002) than the final 50 cases. Conclusions: When compared with the existing literature, incorporation of DAA into fellowship training can lead to reduction in fractures and reoperation rates.

AIMS: Venous thromboembolism (VTE) has a 30-day mortality rate of between 10 and 30%. The Caprini score is a VTE risk assessment model, which assigns points to 20 past medical history and current health factors. We hypothesized that the Caprini score could predict VTE incidence and recommend prophylaxis following total joint arthroplasty. PATIENTS AND METHODS: We performed a retrospective review of prospectively collected institutional data identifying Caprini scores on 2155 primary hip (n = 840) and knee (n = 1315) arthroplasties. Surgeons were blinded to Caprini scores when prescribing VTE prophylaxis. Patients were separated into prophylaxis groups receiving Aspirin (81 mg BID or 325 mg BID) or other (Rivaroxaban, Warfarin, Enoxaparin, Apixaban, Dabigatran, Heparin). Univariate, multivariate, and Cohen's effect size analyses assessed the predictive power of the Caprini score on VTE incidence. RESULTS: The mean Caprini score was 9.49 (5–25). A majority, 83% (1792) of patients were in the Aspirin group, and 17% (363) in the other group. Other prophylaxis patients had statistically significantly higher Caprini scores (10 vs. 9, p 40 or Caprini scores ≥11 to predict VTE incidence in the Aspirin or other prophylaxis groups (p = 0.52 and p = 0.15 respectively). Cohen's effect size was small, comparing Caprini scores in patients who had and had not had a VTE in both Aspirin and other prophylaxis groups (Cohen's d = 0.25 and d = 0.16 respectively). CONCLUSION: Surgeons rely on stronger pharmacologic prophylaxis for a select high risk group of their primary lower extremity total joint arthroplasty patients. When controlling for prophylaxis, the Caprini score had a small effect size and did not have the predictive power necessary to guide treatment

Modular dual mobility cups have been developed to potentially address postoperative hip instability, which can occur in nearly 20% of all revision total hip arthroplasty (THA) patients. By having a prosthetic construct that contains two points of articulation between the femoral head and liner and between the liner and shell, joint stability can be increased. The purpose of this study was to report on dual mobility cup survivorships, patient satisfaction outcomes, complications, and radiographic outcomes at a minimum 7-year follow-up. A high-volume academic surgeon performed a total of 143 consecutive dual mobility primary THAs on patients who had a minimum follow-up of 7 years (range, 7–8.5 years). The study cohort consisted of 77 females (54%) and 66 males (46%) who had a mean age of 65 years (range, 34–90 years). Aseptic, septic, and all-cause survivorship was determined by Kaplan-Meier analysis. Harris Hip Scores (HHS), postoperative complications, and radiographs were also assessed. No cup failures were observed. Overall, septic survivorship was 99.3% (95% confidence interval [CI]: 0.98–1.0) and all-cause survivorship was 98.6% (95% CI: 0.97–1.0). Two patients (1.4%) required revision surgery unrelated to the use of a modular dual mobility cup. Of these, one patient experienced femoral stem loosening and the other developed a periprosthetic infection that was treated with a two-stage revision. The mean total HHS was above 95 points at the most recent follow-up. Three patients (2.3%) experienced medical complications, including two deep vein thromboses and one for nonfatal pulmonary embolism. Radiographic evidence revealed incomplete seating of the metallic liner in one patient. Dual mobility cups were developed in an attempt to decrease the rate of instability following THA. The results from this study indicate that excellent clinical and patient-reported outcomes can be achieved at 7-year follow-up in patients who undergo THA with a dual mobility cup. Therefore, dual mobility cups appear to be an appropriate treatment option for primary THA.

Catheterization for the prophylaxis against or treatment for urinary retention commonly occurs after total knee arthroplasty (TKA). Recent studies have questioned the use of the indwelling catheterization, especially in its potential role as a nidus for infection. We are still unsure of its downstream effects on periprosthetic joint infections (PJIs). Therefore, this study aimed to compare the risks of postoperative PJI following intermittent vs indwelling catheterization after TKA.Between 2017 and 2019, 15 hospitals in a large health system collected data on patients undergoing TKA. Patient treatments with indwelling catheter only, intermittent straight catheter only, and both indwelling and intermittent straight catheterizations were recorded. Patient demographics, comorbidities, body mass indices, and PJIs were collected from time of surgery to time of data collection at mean 14 months of follow-up. Univariate and multivariate analyses were performed with independent t-tests and multiple linear regression models to compare catheterization treatment types.A total of 9123 TKAs were performed, with patients receiving indwelling catheter only (62%, n = 734), intermittent straight catheter only (25%, n = 299), or both indwelling and intermittent catheterizations (13%, n = 160). Univariate analyses showed that PJIs occurred in 1.1% of no-catheter patients and 2.3% of patients treated with bladder catheterization (P = .002). Using multivariate analyses, indwelling catheter use (odds ratio [OR] 2.647, P.001), diabetes (OR 1.837, P = .005), and peripheral vascular disease (OR 2.372, P = .046) were found to have a statistically significant increased risk for PJIs. The use of intermittent straight catheterization (OR 1.249, P = .668) or both indwelling and intermittent (OR 1.171, P = .828) did not increase the risk for PJIs.Urinary bladder catheterization is commonly required for prophylaxis against or treatment for urinary retention following TKA. The use of a urinary catheter can provide a potential nidus for infection in these patients. This study found that indwelling catheterization, but not intermittent catheterization, was associated with an increased risk for PJI. Surgeons should therefore limit the duration of catheterization in an effort to decrease the risk for PJI.

The purpose of this study was to compare the: 1) RVUs; 2) lengths-of-surgery; 3) RVU per minute between revision hip (THA) and knee (TKA) arthroplasties; and 4) perform an annualized surgeon cost analysis. Using the ACS-NSQIP from 2008 to 2015, 8081 revision TKAs, 7233 THAs were compared. Revision THA had greater mean RVUs (30.27 vs. 27.10 RVUs, p

Chronic pain after total joint replacement (TJA), specifically total knee replacement (TKA), is becoming more of a burden on patients, physicians, and the healthcare system as the number of joint replacements performed increases year after year. The management of this type of pain is critical, and therefore, understanding the various modalities physicians can use to help patients with refractory pain after TJA is essential. The modalities by which chronic pain can be successfully managed include genicular nerve radioablation therapy (GN-RFA), neuromuscular electrical stimulation (NMES), transcutaneous electrical nerve stimulation (TENS), and peripheral subcutaneous field stimulation (PSFS). Meta-analyses and case reports have demonstrated the effectiveness of these treatment options in improving pain and functional outcomes in patients with chronic pain after TKA. The purpose of this paper is to review and synthesize the current literature investigating the different ways that refractory pain is managed after TJA, with the goal being to provide treatment recommendations for providers treating these patients.

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.

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(2) (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(2); OR 1.91 [95% CI 1.60 to 2.26]; p < 0.001) and those with morbid obesity (BMI 40-70 kg/m(2); 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.

Because of the early follow-up positive outcomes with cementless fixation, continued evaluations need to be performed to ensure longer-term efficacy. Additionally, although many studies report on the results of femoral and tibial component fixation, few studies report specifically on patellar outcomes. Therefore, the purpose of this study was to report on the: (1) implant survivorship; (2) complications; and (3) radiographic outcomes in a large cohort of patients who received cementless total knee arthroplasties (TKAs), with particular attention to the patellar component. A total of 261 patients who underwent cementless TKA by a single, high-volume academic surgeon were studied. Patients had a mean age of 66 years and were distributed between 192 women (74%) and 69 men. All patients received the same cementless tibial, femoral, and patellar components. Mean follow-up period was 4.5 years (range, 4–5 years). Primary outcomes evaluated included all postoperative complications, with particular emphasis on the patellar component. Only one patellar loosened leading to a patellar aseptic loosening rate of 0.3% (1 of 261). The one patellar loosening was the component being dislodged after a manipulation under anesthesia (MUA) at 6 weeks. This was revised to a cemented component and the patient is doing well 4 years later. A second patient experienced a patellar tendon rupture, later surgically repaired. Another patient sustained a patella fracture that was managed nonoperatively. The fracture healed by 1 year and the patient continued to have an otherwise successful outcome, now at 2 years follow-up. No progressive radiolucencies, subsidence, or changes in initial postoperative axial alignment were observed at final follow-up. The results from this study highlight a 98% success rate at mean 4.5 years follow-up in a large cohort of patients with a diverse spread of demographic details. Specific to the patella, only one patient experienced an adverse event, which was managed nonoperatively. Therefore, based on this data, patellar fixation in cementless TKA can be considered a safe technique.

Rapid recovery protocols (RRP) in total hip arthroplasty (THA) aim to decrease patient length of stay (LOS), reduce postoperative pain, minimize complications, and improve patient satisfaction. RRP require attention to detail during preoperative, intraoperative, and postoperative care. Despite being referred to as the practice of medicine, most of the “practices,” including the physical, mental, and emotional energy, should occur before entering into the operating room. The operating room should be reserved for execution of a well-thought-out and prepared surgical plan (and backup plans) with efficiency.

Urinary bladder catheters are potential sources of infection after total hip arthroplasty (THA). Therefore, the goal of this study was to determine if intermittent catheterization provides a decreased risk of postoperative urinary tract infections (UTIs) compared with indwelling catheterization in THA patients.Patients undergoing THA at 15 hospitals within a large health system were prospectively collected between 2017 and 2019 and then stratified based on catheterization technique: no-catheter; indwelling catheter-only; intermittent catheter-only; and both intermittent and indwelling catheter. Patient demographics, medical comorbidities, anesthesia types, and postoperative UTIs were assessed. Independent Student t-tests were used to perform univariate analyses for the catheterization groups. Multiple linear regression models were used to compare the different groups while controlling for confounding variables.There were a total of 7306 THA patients recorded with 5513 (75%) no-catheter, 1181 (16%) indwelling catheter-only, 285 (3.9%) intermittent catheter-only, and 327 (4.5%) indwelling and intermittent catheterization patients. A total of 580 patients experienced postoperative UTI. Urinary bladder catheterization increased the risk of postoperative UTIs (P.001) in univariate analyses. Multiple linear regression models showed that indwelling catheter-only (OR: 2.178, P.001), intermittent catheterization (OR: 1.975, P = .003), and both indwelling and intermittent (OR: 2.372, P = .002) were more likely to experience UTIs compared with no catheters.This study found that patients treated with indwelling catheterization, with or without preceding intermittent catheterization, were significantly more likely to experience UTIs. Therefore, in an effort to decrease the risk of UTIs, THA patients experiencing postoperative urinary retention should be treated with intermittent catheterization.

Substance abuse disorder (SUD), alcohol abuse disorder (AUD), and depression have been identified as independent risk factors for complications after total knee arthroplasty (TKA). However, these mental health disorders are highly co-associated, and their cumulative effect on postoperative complications have not been investigated. Therefore, this study aimed to determine if patients who have more than one mental health disorder (SUD, AUD, or depression) were at an increased risk for postoperative complications following TKA.A total of 11,403 TKA patients were identified from a prospectively collected institutional database between January 1, 2017 and April 1, 2019. Patients who had depression, SUD, and AUD were separated into 7 mental health subgroups including each of these diagnoses alone and their combined permeations. Patient demographics, body mass indices, medical comorbidities, and 15 postoperative complications were collected. Univariate analyses were performed using independent Student's t-tests. Multivariate analyses were then performed to identify odds ratios (ORs) for mental health disorders subgroups associated with complications.We found a total of 2073 (18%) patients diagnosed with either SUD (4%), AUD (0.6%), or depression (12%). Univariate analyses showed that depression was associated with mechanical failures (P.001). SUD was associated with periprosthetic joint infection (PJI) (P.001), wound complications (P = .022), and aseptic loosening (P = .007). AUD was associated with PJI (P.001) and deep vein thromboses (P = .003). Multivariate analyses found that AUD (OR: 19.419, P.001) and SUD (OR:3.693, P = .010) were independent risk factors for PJI. Compared with SUD alone, patients with depression plus SUD were found to have a 4-fold (OR: 13.639, P.001) and 2-fold (OR:4.401, P = .021) increased risk for PJI and cellulitis, respectively.Patients who had depression, SUD, or AUD were at increased risk for postoperative complications following primary TKA. When patients have more than one mental health diagnosis, their risk for complications was amplified. The results of this study can help identify those patients who are at greater risk of postoperative complications to enable improved preoperative optimization and patient education.

Although intermittent catheters are immediately removed, indwelling catheterization may lead to decreased ambulation and participation in physical therapy, critical components to post-total knee arthroplasty (TKA) management. Therefore, this study aimed to compare the effect of catheterization treatments on (1) postoperative ambulation distances, (2) deep vein thromboses (DVTs), and (3) pulmonary emboli (PEs) following TKA.A total of 9123 prospectively collected primary TKA patients were assessed based on postoperative catheter status. Patient demographics, Charlson Comorbidity Indices, body mass indices, DVT prophylaxes, first ambulation distances, DVTs, and PEs were collected at approximately mean 12 months of follow-up. Univariate and multivariate analyses were performed with independent t-tests and multiple linear regression models in order to compare catheterization techniques.There were 1193 patients who had urinary retention and treated with either indwelling only (62%, n = 734), both indwelling and intermittent catheterizations (13%, n = 160), or intermittent only (25%, n = 299). Multivariate analyses found that indwelling catheter-only use had an 11% decrease in ambulation distance (P.001). Additionally, the indwelling catheterization-only group was found to be at increased risk of DVTs (odds ratio 2.605, P.001), even after controlling for DVT prophylaxes (odds ratio 2.807, P.001).This study showed that the use of an indwelling catheter for treatment of urinary retention significantly decreased TKA patient ambulation distance and subsequently increased the risk for DVTs. This information is important as we would recommend the treatment with intermittent catheterization rather than indwelling catheters to decrease the risk of immobilization and postoperative DVTs.

Introduction:Robotic-arm assisted surgery allows for the execution of well-aligned knee arthroplasty regardless of pre-existing deformity. This case series is presented to show the utility of robotic-arm assisted TKA in achieving well-balanced, well-aligned results in a variety of challenging scenarios.Methods:We present seven challenging cases of robotic-arm assisted total knee arthroplasty. There were two conversion TKAs following a previous surgery. One case featured a previous tibial plateau fracture treated with a plate and screws construct while another featured a prior femoral nail with significant bony overgrowth. Five cases of severe deformity were also identified, with one tibial nonunion, two valgus knees and one patient with two varus knees due psoriatic arthritis treated with staged bilateral TKAs. Patient clinical history, physical examinations, intraoperative surgical techniques and postoperative courses were recorded.Results:All cases were able to utilize effective preoperative planning to obtain precise intraoperative bone cuts and component positioning. Each of the seven cases achieved well-balanced, well-aligned arthroplasties. There were no intraoperative or postoperative complications. At latest follow up, all patients showed significant improvements in pain and ambulation compared to preoperative exams.Discussion:Robotic-arm assisted surgery allows for the integration of preoperative CT scans to establish and execute a surgical plan with precision. Despite the complexity of these cases, excellent results were achieved without the need for revision-type components. These cases display the ability of robotic-arm assisted surgery to achieve consistent well-aligned results with minimal bone loss in challenging total knee arthroplasty cases.

Several recent intraoperative and wound management techniques have been developed and implemented in the United States over the past decade; however, it is unclear what the effects of these newer modalities have on reducing surgical site infection (SSI) rates. Therefore, the purpose of this study was to track the annual rate and trends of (1) overall, (2) deep, and (3) superficial SSIs following revision total knee arthroplasty (TKA). The National Surgical Quality Improvement Program database was queried for all revision TKA cases performed between 2011 and 2016, which yielded 9,887 cases. Cases with superficial and/or deep SSIs were analyzed separately and then combined to evaluate overall SSI rates. After an overall 6-year correlation and trends analysis, univariate analysis was performed to compare the most recent year, 2016, with the preceding 5 years. Correlation coefficients and chi-square tests were used to determine correlation and statistical significance. No significant correlations between combined, deep, and/or superficial SSI rates and year were noted (p > 0.05). The lowest overall SSI incidence was in 2012 (1.16%), while the greatest incidence was in 2014 (1.76%). The deep SSI incidence over the 6 years was 0.67% (66 out of 9,887 cases). Deep SSI rate decreased by 10% in 2016 compared with 2011 (0.50 vs. 0.56%, p > 0.05). In this 6-year period, 94 cases out of 9,887 were complicated by a superficial SSI, an incidence of 0.95%. The lowest superficial SSI incidence occurred in 2015 (n = 17, 0.77%). Overall, the incidence of SSIs in revision TKA has remained fairly low with some annual variance, indicating room for improvement. These variations likely as revision surgeries can be more complex and have several associated confounding factors influencing outcomes, when compared with primary cases. Further research is needed to identify revision-specific strategies to reduce the risk of surgical site infections.

BACKGROUND: Relative value units (RVUs) are a physician reimbursement model based on the effort required, or value, in providing a procedure or service for a patient. Procedures such as conversion total hip arthroplasties (THAs) can be compared to primary THAs, but many studies have revealed increased difficulties in conversion cases. Despite the increased time and effort for conversion THA, it is unknown if this is reflected in the RVU compensation model. Therefore, the purpose of this study was to compare the: (I) mean operative times; (II) mean RVUs; (III) RVU/minute for primary and conversion THAs; and (IV) perform an individualized idealized surgeon annual cost difference analysis. METHODS: A total of 103,702 primary THA patients were identified using CPT code 27130 and 2,986 conversion THA patients were identified using CPT code 27132 using the National Surgical Quality Improvement Program (NSQIP) database. The mean RVUs, operative times (minutes), and RVU/minute were calculated and compared. An annualize cost analysis of dollar amounts per case, day, and the year was also performed. RESULTS: The mean operative times for the primary and conversion THA cohorts were 94 vs. 146 minutes (P

The purpose of this study is to track the 30-day postoperative annual rates and trends of (1) overall, (2) deep, and (3) superficial surgical site infections (SSIs) following total hip arthroplasty (THA) using a large nationwide database.The National Surgical Quality Improvement Program database was queried for all THA cases performed between 2012 and 2016. After an overall 5-year correlation and trends analysis, univariate analysis was performed to compare the most recent year, 2016, with the preceding 4 years. Correlation coefficients and chi-squared tests were used to determine correlation and statistical significance.The lowest incidence of SSIs was in the most recent year, 2016 (0.81%), while the greatest incidence was in the earliest year, 2012 (1.12%), marking a 31% decrease (P.01). The lowest rate was in the most recent year, 2016 (0.23%), marking a 26% decrease from 2012. The lowest superficial SSI incidence occurred in the most recent year, 2016 (0.58%), while greatest incidence was in 2012 (0.83%), marking a 31% decrease over time (P.05). There was an inverse correlation among overall, deep, and superficial SSI rates with operative year.The findings from this study suggest a decreasing trend in SSIs within 30 days following THA. Furthermore, deep SSIs, which can pose substantial threats to implant survivorship, have also decreased throughout the years. These results highlight that potentially through improved medical and surgical techniques, we are winning the fight against short-term infections, but that more can still be done.

BACKGROUND: Revision total knee arthroplasty (TKA) is associated with increased rates of infections, readmissions, longer operative times, and lengths-of-stay (LOS) compared to primary TKA. Additionally, increasing operative times and prolonged postoperative LOS are independent risk factors for these postoperative complications in lower extremity total joint arthroplasty (TJA). This has led to an increased effort to reduce these risk factors in order to improve patient outcomes and reduce cost. However, the relationship between operative time and LOS has not been well assessed in revision arthroplasty. Therefore, the purpose of this study was to: (I) identify predictors of longer operative times; (II) identify predictors of longer LOS; and (III) evaluate the effects of operative time, treated as both a categorical variable and a continuous variable, on LOS after revision TKA. METHODS: The NSQIP database was queried for all revision TKA cases (CPT code 27487) between 2008 and 2016 which yielded 10,604 cases. Mean operative times were compared between patient demographics including age groups, sex, and body mass indexes (BMIs). To determine predictors of LOS, mean LOS were also compared between patient demographics in the same groups. To assess the correlation of operative time on LOS, the mean LOS for 30-minute operative time intervals were compared. Univariate analysis was performed with one-way analysis of variance (ANOVA) and t-tests. A multivariate analysis with a multiple linear regression model was performed to evaluate the association of LOS with operative times after adjusting for patient age, sex, and BMI. RESULTS: The mean LOS for revision TKA was 4 (±3) days. Further analysis showed that young age is associated with increased LOS (P

Owing to an extensive range of motion, the stability of the shoulder joint depends heavily on important ligament and muscular attachments. Overuse or acute injuries to any of these structures predisposes to the pathologic conditions of shoulder pain and instability. Isolation of anatomic structures through physical exam is crucial to develop a differential diagnosis and treatment plan.

The hip is a ball-and-socket joint with robust muscular attachments. Hip pain can originate from spinal, intra-articular, and systemic pathologic issues which often renders diagnosis difficult. Range of motion deficits, specific physical exam tests, and radiographic imaging are useful for developing a differential diagnosis.

The specific influence of operative times on lengths-of-stay (LOS) has not been well assessed and is therefore an important topic of evaluation for multiple reasons, including potential economic implication. The purpose of this study is to (1) identify predictors of longer operative times; (2) identify predictors of longer LOS; and (3) evaluate the effects of operative times on LOS in primary total knee arthroplasty (TKA).The National Surgical Quality Improvement Program database was queried for primary TKAs performed between 2008 and 2016, yielding 225,344 cases. Multivariate analysis was performed to determine the effect of operative times on LOS after adjusting for patient factors. Univariate analyses were performed with 1-way analysis of variance (ANOVA), linear regression, and independent sample t-tests where appropriate. Multivariate analysis was performed with a multiple linear regression model adjusted for patient age, sex, and body mass index (BMI).The mean operative time was 93 ± 35 minutes and the mean LOS was 3 ± 3 days. Young age, male sex, and obesity were predictors of longer operative times (P.001). Similarly, there were significant associations of age, sex, and BMI with LOS (P.001). Increasing 30-minute operative time intervals were associated with increasing LOS (P.001). Longer operative times had significant associations with longer LOS even after adjusting for patient factors (β = 0.076, SE0.001, P value.001). Out of all study covariates, operative times had the greatest effect on LOS.This study provides unique insight by directly correlating operative times to LOS in over 200,000 TKAs. The results from this study indicate that there is a strong correlation between operative times and LOS, so that operative time had a greater association than age, sex, and BMI with postoperative TKA LOS.

BACKGROUND: Elective total hip arthroplasties (THAs) entail a more extensive pre-operative planning process compared to non-elective THAs and this may contribute to a disparity in outcomes. However, the differences in peri- and post-operative outcomes between elective and non-elective THAs remain unclear. Therefore, the purpose of this study was to: (I) determine nationwide trends in operative times and (II) evaluate the association between surgery type, elective or non-elective with respect to (I) operative times; (II) hospital lengths-of-stay (LOS); (III) discharge disposition; (IV) 30-day post-operative complications; (V) reoperations; and (VI) readmissions. METHODS: The NSQIP database was queried for all primary THAs (CPT code 27130) performed between 2011 and 2016. This yielded 130,261 cases, which were then stratified into elective (n=125,293) and non-elective (n=4,968) cases. One-way analysis of variance (ANOVA) were used to evaluate the associations between operative times and surgery year. Univariate analyses of surgery type with the following outcomes of interest were also performed: operative times, LOS, and discharge disposition as well as 30-day complication, reoperation, and readmission rates. A multiple linear regression model was used to evaluate the relationships of operative times and LOS with surgery types after adjusting for surgery year and patient factors [age, sex, body mass index (BMI), and American Society of Anesthesiologists (ASA) score]. A log-transformed dependent variable was used to calculate the percentage difference in mean operative times and LOS. Multivariate logistic regression models adjusted for patient factors and year of surgery were used to evaluate associations of surgery type with complication, reoperation, and readmission rates. RESULTS: Over the 6-year period, mean operative times (93 vs. 103 minutes, P

BACKGROUND: Substantial efforts have been made to reduce the risk of infection after total hip arthroplasty (THA), including pre-operative patient optimization, skin preparation with alcohol-based solutions, perioperative antibiotics, and minimizing wound drainage with novel sutures and dressings. While these approaches have been effective in primary THA, their effects on revision THA to improve surgical site infection (SSI) rates are less clear. Therefore, the purpose of this study was to identify the annual rates and trends of: (I) overall; (II) deep; and (III) superficial SSIs following revision THA using the most recent results (2011 to 2016) from a large, nationwide database. METHODS: The National Surgical Quality Improvement Program (NSQIP) database was queried for all revision THA cases (CPT code 27134) between 2011 and 2016, yielding 8,562 cases. A steady increase in the total number of revision THA cases was observed from 2011 to 2016 (750 vs. 1,951, 260%). Cases with reported superficial and/or deep SSI were analyzed separately and then combined to evaluate overall SSI rates. The infection incidence for each year was calculated. After an overall 6-year correlation and trends analysis, univariate analysis was performed to compare the most recent year, 2016, with each of the preceding 5 years. Additionally, percent differences between 2016 and each previous year were calculated to evaluate rate changes. Pearson correlation coefficients and chi-squared tests were used to determine correlation and statistical significance which was maintained at a P value less than 0.05. RESULTS: There were 217 cases out of 8,562 (2.53% of all cases) complicated by any SSI. Overall, there was an inverse correlation between combined SSI rate and year, however, this was not statistically significant (P>0.05). The lowest incidence was in 2016 (n=41, 2.10%), while the highest incidence was in 2014 (n=45, 2.86%). The combined SSI rate in 2016 decreased by 22% when compared to 2015 (2.10% vs. 2.69%, P>0.05). A larger, 27% decrease in rate was found between 2016 and 2014 (2.10% vs. 2.86%, P>0.05). For deep SSI, there was an inverse correlation between rate and year of surgery, however, this was not statistically significant (P>0.05). The deep SSI incidence over the 5 years was 1.38% (118 out of 8,562 cases). There was a 35% decrease in deep SSI rate from 2016 to 2015 (0.92% vs. 1.43%, P>0.05). A larger, 53% decrease, was seen between 2016 and 2014 (0.92% vs. 1.04%, P0.05). In this 6-year period, 99 cases out of 8,562 were complicated by a superficial SSI; an incidence of 1.16%. The lowest incidence occurred in 2014 (n=14, 0.89%), while 2012 had the highest incidence (n=17, 1.61%). The rate in 2016 decreased by 6% when compared to 2015 (1.18% vs. 1.07%, P>0.05). A larger, 27% decrease in rate was observed between 2016 and 2012 (1.18% vs. 1.61%, P>0.05). CONCLUSIONS: Revision total hip arthroplasties exhibited a trend towards decreasing overall SSI nationwide between 2011 and 2016. Deep SSI rates had marked improvements, specifically between 2014 and 2016. This trend indicates some benefit from pre- and post-operative infection preventative strategies, but importantly, indicates continued room for improvement. Due to the potentially devastating complications associated with infection in revision THAs, further research is required to identify revision-specific strategies to lower the rates of SSIs.

PVD-Beschichtungen konnen die Eigenschaften trockenlaufender Hybridwalzlager verbessern. So kann der Verschleis, aber auch das Reibmoment mit ihrer Hilfe herabgesetzt werden. Um dies zu erreichen, wurden PVD-Schichten im Hinblick auf die auftretenden Belastungen weiterentwickelt. Untersuchungen mit Hilfe des standardisierten FE8-Walzlagerprufstands dienten zum Nachweis des Potentials der PVD-Beschichtungen fur den Trockenlauf. Die Ergebnisse dieser Untersuchung wiederum flossen in die Schichtentwicklung ein. PVD coatings for dry running hybrid roller bearings PVD coatings are able to improve the characteristics of dry running hybrid roller bearings. Wear and friction moment can be reduced by coatings. Therefore PVD coatings were adjusted for the appearing loads. Examinations with the help of the standardised FE8 test-rig were used to verify the potential of PVD coatings in dry running applications. The results of the tests were taken into account for further coating development.

The NVH optimization of single components of a machine system, e.g. engine with transmission, leads not always to improvements of the complete system. Single optimized components may result in unwanted noise when combined due to unforeseen interaction. Therefore it is crucial for the development of low noise products to consider the entire noise generation path (excitation, structural transfer behavior, radiation). The Institute for Machine Elements of Aachen Technical University and the Institute for Combustion Engines of Aachen Technical University developed in a cooperation a simulation method to investigate the noise generation path of a engine-transmission powertrain [1].

For the realization of environmental compatible tribosystems within the special research centre SFB 442 PVD coated systems are developed, which improve the tribological characteristics together in interaction with compatible lubricants. For the evaluation of coated substrate systems employed in tribosystems, it is significant to characterize the mechanical stress collective within the systems by means of their mechanical properties. Subject of the presented investigations is an analysis about the properties of the systems that have significant effects on the system stress collective. Differences to the well-known surface stress of solid materials are pointed out and mathematical models for the description are developed to describe the influence of coated substrates. The aim of these investigations is to draw a connection between these stresses occurring in tribosystems (e.g. industrial applications bearings) and the loads applied in test methods e.g. microindentation (Rockwell Hardness Tests) and nanoindentation. To evaluate the stresses applied in real tribosystems the theory of micro contact mechanics of Greenwood and Williamson is used and is found to be appropriate. Since, only with this connection it is possible to consult the results gained in the coating test methods for the evaluation of a coated system. Essential aid in here is the simulation of the mechanical surface stresses by means of FEM (finite element method). At this point it is possible to take the anisotropic and inhomogeneous material properties of the coating material and the substrate into account.Copyright © 2005 by ASME

Regarding driving units with combustion engines, it is primarily the torsional vibrations caused by the unsymetrical gas forces, inertial forces and out-of-balance forces which may cause harm to the driveline. The program DRESP was developed at the Institute of Machine Elements and Machine Design (IME) of the RWTH Aachen in order to simulate such nonlinear torsional vibration systems. The program has been established as an efficient simulation tool in numerous companies for driveline analysis. Fourier series of gas pressure moments are used for the simulation of torsional vibrations in order to simulate the periodic excitation of combustion engines. But this is only applicable at a certain stationary operation point of the engine. To avoid this disadvantage, a simulation model based on a combustion process calculation can be used instead. It computes the gas and mass excitation forces by modeling the combustion process and the kinematic of the crank drive for every cylinder. The theoretical basis is the so called One Zone Model according to Vibe which is a simplified thermodynamic model of the cylinder. The presentation shows a DRESP-simulation using the example of a modern marine drive with a two-stroke diesel engine. It shows the dynamic behavior of the power-train during an engine-startup process from zero to nominal speed.Copyright © 2003 by ASME

Separation de jumeaux omphalopuboperineopages en 5 heures. Deux equipes d'anesthesie sont necessaires avec chacune 2 personnes