In-hospital surgical site infections after primary hip and knee arthroplasty--incidence and risk factors

The projected burden of complex surgical site infections following hip and knee arthroplasties in adults in the United States, 2020 through 2030

BACKGROUND

As the US population ages, the number of hip and knee arthroplasties is expected to increase. Because surgical site infections (SSIs) following these procedures contribute substantial morbidity, mortality, and costs, we projected SSIs expected to occur from 2020 through 2030.

METHODS

We used a stochastic Poisson process to project the number of primary and revision arthroplasties and SSIs. Primary arthroplasty rates were calculated using annual estimates of hip and knee arthroplasty stratified by age and gender from the 2012-2014 Nationwide Inpatient Sample and standardized by census population data. Revision rates, dependent on time from primary procedure, were obtained from published literature and were uniformly applied for all ages and genders. Stratified complex SSI rates for arthroplasties were obtained from 2012-2015 National Healthcare Safety Network data. To evaluate the possible impact of prevention measures, we recalculated the projections with an SSI rate reduced by 30%, the national target established by the US Department of Health and Human Services (HHS).

RESULTS

Without a reduction in SSI rates, we projected an increase in complex SSIs following hip and knee arthroplasty of 14% between 2020 and 2030. We projected a total burden of 77,653 SSIs; however, meeting the 30% rate reduction could prevent 23,297 of these SSIs.

CONCLUSIONS

Given current SSI rates, we project that complex SSI burden for primary and revision arthroplasty may increase due to an aging population. Reducing the SSI rate to the national HHS target could prevent 23,000 SSIs and reduce subsequent morbidity, mortality, and Medicare costs.

Postoperative Blood Glucose Levels Predict Infection After Total Joint Arthroplasty

BACKGROUND

Perioperative hyperglycemia has many etiologies, including medication, impaired glucose tolerance, uncontrolled diabetes mellitus, or stress, the latter of which is common in patients postoperatively. Our study investigated the influence of postoperative blood glucose levels on periprosthetic joint infection after elective total joint arthroplasty to determine a threshold for glycemic control for which surgeons should strive during a patient's hospital stay.

METHODS

A single-institution retrospective review was conducted on 24,857 primary total joint arthroplasties performed from 2001 to 2015. Of these, 13,196 had a minimum follow-up of 1 year (mean, 5.9 years). Postoperative day 1 morning blood glucose levels were utilized and were correlated with periprosthetic joint infection, as defined by the International Consensus Group on Periprosthetic Joint Infection. Multivariable analysis was used to determine the influence of several important covariates on infection. An alpha level of 0.05 was used to determine significance.

RESULTS

The rate of periprosthetic joint infection increased linearly from blood glucose levels of ≥115 mg/dL. Multivariable analysis revealed that blood glucose levels were significantly associated with periprosthetic joint infection (p = 0.028). The optimal blood glucose threshold to reduce the likelihood of periprosthetic joint infection was 137 mg/dL. The periprosthetic joint infection rate in the entire cohort was 1.59% (1.46% in patients without diabetes compared with 2.39% in patients with diabetes; p = 0.001). There was no significant association between blood glucose level and periprosthetic joint infection in patients with diabetes (p = 0.276), although there was a linear trend.

CONCLUSIONS

The relationship between postoperative blood glucose levels and periprosthetic joint infection increased linearly, with an optimal cutoff of 137 mg/dL. Immediate and strict postoperative glycemic control may be critical in reducing postoperative complications, as even mild hyperglycemia was significantly associated with periprosthetic joint infection.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Surgical masks as source of bacterial contamination during operative procedures

Background

Surgical masks (SMs) are used to reduce bacterial shedding from the mouth, nose and face. This study aimed to investigate whether SMs may be a potential source of bacterial shedding leading to an increased risk of surgical site infection.

Methods

Bacterial contamination of the SMs was tested by making an impression of the external surface of the mask on sterile culture media immediately. We investigated the difference in bacterial counts between the SMs worn by surgeons and those placed unused in the operating room (OR), and the bacterial count variation with indicated wearing time. Moreover, the difference in bacterial counts on the external surface between the first and second layers of double-layered SMs was also assessed.

Results

The bacterial count on the surface of SMs increased with extended operating times; significant difference was found between the 4- to 6-hour and 0-hour groups (p < 0.05). When we analysed the bacterial counts from the same surgeon, a significant increase was noted in the 2-hours group. Moreover, the bacterial counts were significantly higher among the surgeons than the OR. Additionally, the bacterial count of the external surface of the second mask was significantly higher than that of the first one.

Conclusions

The source of bacterial contamination in SMs was the body surface of the surgeons rather than the OR environment. Moreover, we recommend that surgeons should change the mask after each operation, especially those beyond 2 hours. Double-layered SMs or those with excellent filtration function may also be a better alternative.

The translational potential of this article

This study provides strong evidence for the identification that SMs as source of bacterial contamination during operative procedures, which should be a cause for alarm and attention in the prevention of surgical site infection in clinical practice.

Relationship Between Staphylococcus aureus Carriage and Surgical Site Infections Following Total Hip and Knee Arthroplasty in the South Asian Population: Protocol for a Prospective Cohort Study

Background

Surgical site infections following total hip or knee arthroplasties have a reported rate of 0.49%-2.5% and can cause significant morbidity as well as tripling the cost of health care expenses. Both methicillin sensitive and methicillin resistant strains of Staphylococcus aureus surgical site infections have been established as a major risk factor for postoperative surgical site infections. S. aureus colonizes the nose, axillae, and perineal region in up to 20%-30% of individuals. Although the literature has reported a higher prevalence of methicillin resistant S. aureus in the South Asian population, routine preoperative screening and prophylaxis have not yet been implemented.

Objective

The primary objective of our study is to identify the relationship between preoperative colonization status of S. aureus and incidence of postoperative surgical site infections in patients undergoing following total hip and knee arthroplasties. As part of the secondary objectives of this study, we will also investigate patient characteristics acting as risk factors for S. aureus colonization as well as the outcomes of total hip and knee arthroplasty patients which are affected by surgical site infections.

Methods

This prospective cohort study will comprise of screening all patients older than 18 years of age admitted to the Aga Khan University Hospital for a primary total hip or knee arthroplasty for preoperative colonization with S. aureus. The patients will be followed postoperatively for up to one year following the surgery to assess the incidence of surgical site infections. The study duration will be 2 years (March 2018 to March 2020). For the purpose of screening, pooled swabs will be taken from the nose, axillae, and groin of each patient and inoculated in a brain heart infusion, followed by subculture onto mannitol salt agar and sheep blood agar. For methicillin resistant S. aureus identification, a cefoxitin disk screen will be done. Data will be analyzed using SPSS v23 and both univariate and multivariate regression analysis will be conducted.

Results

Data collection for this study will commence at the Aga Khan University Hospital, Pakistan during March 2018.

Conclusions

This study will not only estimate the true burden caused by S. aureus in the population under study but will also help identify the patients at a high risk of surgical site infections so that appropriate interventions, including prophylaxis with antibiotics such as muciprocin ointment or linezolid, can be made. Given the differences in lifestyle, quality, and affordability of health care and the geographical variation in patterns of antibiotic resistance, this study will contribute significantly to providing incentive for routine screening and prophylaxis for S. aureus including methicillin resistant S. aureus colonization in the South Asian population.

Registered Report Identifier

RR1-10.2196/10219

Rate and Risk Factors for Periprosthetic Joint Infection Among 36,494 Primary Total Hip Arthroplasties

BACKGROUND

As periprosthetic joint infections (PJIs) can have tremendous health and socioeconomic implications, recognizing patients at risk before surgery is of great importance. Therefore, we sought to determine the rate of and risk factors for deep PJI in patients undergoing primary total hip arthroplasty (THA).

METHODS

Clinical characteristics of patients treated with primary THA between January 1999 and December 2013 were retrospectively reviewed. These included patient demographics, comorbidities (including the Charlson/Deyo comorbidity index), length of stay, primary diagnosis, total/allogeneic transfusion rate, and in-hospital complications, which were grouped into local and systemic (minor and major). We determined the overall deep PJI rate, as well as the rates for early-onset (occurring within 2 years after index surgery) and late-onset PJI (occurring more than 2 years after surgery). A Cox proportional hazards regression model was constructed to identify risk factors for developing deep PJI. Significance level was set at 0.05.

RESULTS

A deep PJI developed in 154 of 36,494 primary THAs (0.4%) during the study period. Early onset PJI was found in 122 patients (0.3%), whereas late PJI occurred in 32 patients (0.1%). Obesity, coronary artery disease, and pulmonary hypertension were identified as independent risk factors for deep PJI after primary THA.

CONCLUSION

The rate of deep PJIs of the hip is relatively low, with the majority occurring within 2 years after THA. If the optimization of modifiable risk factors before THA can reduce the rate of this complication remains unknown, but should be attempted as part of good practice.

Readmission, Reoperation, and Complications: Total Hip vs Total Knee Arthroplasty

BACKGROUND

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are currently grouped under the same Diagnosis-Related Group (DRG). With the introduction of bundled payments, providers are accountable for all the costs incurred during the episode of care, including the costs of readmissions and management of complications. However, it is unclear whether readmission rates and short-term complications are similar in primary THA and TKA.

METHODS

The National Surgical Quality Improvement Project database was queried from 2011 to 2015 to identify 248,150 primary THA/TKA procedures using Current Procedural Terminology codes. After excluding 1602 hip fractures and 5062 bilateral procedures, 94,326 THAs and 147,160 TKAs were included in the study. Length of stay, discharge disposition, and 30-day readmission, reoperation and complication rates were compared between THA and TKA using multivariate regression models.

RESULTS

After adjusting for baseline characteristics, length of stay (P = .055) and discharge disposition (P = .304) were similar between THA and TKA. But the 30-day rates of readmission (P < .001) and reoperation (P < .001) were higher in THA. Of the 18 complications evaluated in the study, 7 were higher in THA, 3 were higher in TKA, and 8 were similar between THA and TKA.

CONCLUSION

THA patients had higher 30-day rates of readmission and reoperation. As both readmissions and reoperations can result in higher episode costs, a common target price for both THA and TKA may be inappropriate. Further studies are required to fully understand the extent of differences in the episode costs of THA and TKA.

Perioperative Allogeneic Red Blood-Cell Transfusion Associated with Surgical Site Infection After Total Hip and Knee Arthroplasty

BACKGROUND

Perioperative allogeneic red blood-cell transfusion is a suspected risk factor for surgical site infection (SSI) after total joint arthroplasty (TJA), but the interrelationships among SSI risk, transfusion dose, preoperative anemia, and the presence of coagulopathies have not been well described.

METHODS

Data on SSI within 1 year after surgery as well as on transfusion with blood products within 30 days after surgery were obtained for 6,788 patients who had undergone primary or revision total hip or knee arthroplasty from 2000 to 2011 in a single hospital system. Multivariate logistic regression modeling was used to determine the independent association between allogeneic red blood-cell transfusion and SSI.

RESULTS

There was a dose-dependent association between allogeneic red blood-cell transfusion and SSI, with the infection rate increasing as the transfusion dose increased from 1 unit (odds ratio [OR] = 1.97; 95% confidence interval [CI] = 1.38, 2.79; p < 0.001), to 2 units (OR = 2.20; CI = 1.37, 3.44; p = 0.002), to 3 units (OR = 3.66; CI = 1.72, 7.16; p = 0.001), and to >3 units (OR = 7.40; CI = 4.91, 11.03; p < 0.001) after controlling for medical comorbidities, planned procedure, preoperative anemia, and preexisting coagulopathies. A preexisting bleeding disorder (OR = 2.09; CI = 1.57, 2.80; p < 0.001) and clotting disorder (OR = 1.37; CI = 1.14, 1.64; p = 0.001) and preoperative anemia (OR = 3.90; CI = 3.31, 4.61; p < 0.001) were all independent risk factors for transfusion after adjusting for the planned procedure.

CONCLUSIONS

We found a dose-dependent relationship between allogeneic red blood-cell transfusion and SSI risk after total hip or knee arthroplasty. Additionally, preoperative anemia or a known bleeding or clotting disorder were risk factors for the need for allogeneic red blood-cell transfusion. Our findings underscore the need for preoperative risk assessment, methods to limit surgical tissue injury, and optimized blood conservation strategies.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Smoking on Thirty-Day Postoperative Complications After Total Joint Arthroplasty: A Propensity Score-Matched Analysis

BACKGROUND

Total joint arthroplasty (TJA) is a highly successful treatment, but is burdensome to the national healthcare budget. National quality initiatives seek to reduce costly complications. Smoking's role in perioperative complication after TJA is less well known. This study aims to identify smoking's independent contribution to the risk of short-term complication after TJA.

METHODS

All patients undergoing primary TJA between 2011 and 2012 were selected from the American College of Surgeon's National Surgical Quality Improvement Program's database. Outcomes of interest included rates of readmission, reoperation, mortality, surgical complications, and medical complications. To eliminate confounders between smokers and nonsmokers, a propensity score was used to generate a 1:1 match between groups.

RESULTS

A total of 1251 smokers undergoing TJA met inclusion criteria. Smokers in the combined total hip and knee arthroplasty cohort had higher 30-day readmission (4.8% vs 3.2%, P = .041), were more likely to have a surgical complication (odds ratio 1.84, 95% confidence interval 1.21-2.80), and had a higher rate of deep surgical site infection (SSI) (1.1% vs 0.2%, P = .007). Analysis of total hip arthroplasty only revealed that smokers had higher rates of deep SSI (1.3% vs 0.2%, P = .038) and higher readmission rate (4.3% vs 2.2%, P = .034). Analysis of total knee arthroplasty only revealed greater surgical complications (2.8% vs 1.2%, P = .048) and superficial SSI (1.8% vs 0.2%, P = .002) in smokers.

CONCLUSION

Smoking in TJA is associated with higher rates of SSI, surgical complications, and readmission.

Perioperative Outcomes and Complications in Patients With Heart Failure Following Total Knee Arthroplasty

BACKGROUND

Heart failure (HF) is a common comorbidity in the aging population and they will require major elective surgery. The purpose of this study is to determine if HF is a risk factor for adverse perioperative outcomes and short-term complications following total knee arthroplasty.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was utilized to identify all patients who underwent total knee arthroplasty for osteoarthritis from 2008 to 2014. Any diagnosis other than osteoarthritis was excluded. A total of 111,634 patients were identified and 251 of these patients had a preoperative diagnosis of HF. The main outcomes included operative time, lengths-of-stay, discharge disposition, return to operating room, readmission, and short-term complications, including death.

RESULTS

Patients with HF were found to have longer hospital stays (β = 0.59, 95% confidence interval [CI] 0.12-1.06) following total knee arthroplasty, and were more likely to return to the operating room (odds ratio 2.00, 95% CI 1.01-3.94) and be readmitted (OR 1.88, 95% CI 1.21-2.94). In addition, HF was found to be a risk factor for 1 or more complications (OR 1.41, 95% CI 1.05-1.90), wound dehiscence (OR 4.86, 95% CI 1.68-14.03), and myocardial infarction (OR 4.81, 95% CI 1.90-12.16) postoperatively.

CONCLUSION

Patients with HF are more likely to have a longer length-of-stay, return to the operating room, and be readmitted. Additionally, they have a higher risk for at least one postoperative complication, myocardial infarction, and wound dehiscence.

Social profile and cost analysis of deep infection following total hip replacement surgery

Objective

To characterize the socio-economic and demographic profile of patients undergoing surgery for revision total hip arthroplasty regarding the diagnosis of deep prosthetic infection.

Methods

Twenty patients were retrospectively studied, admitted in the period between 2009 and 2010 by the Hip Surgery Group with the diagnosis of deep prosthetic infection, whose proposed treatment was surgical. This study was carried out in the presence of the patient by completing two forms applied by the social worker of the Group.

Results

In a 20-patient sample, 40% were male, 45% were working age, 50% of patients originated from the capital, 85% depended on benefits, 70% were retired, 60% of patients were from this hospital, and 40% were from other services. The average cost of patients to the public system was R$ 55,821.62 per patient and the total spent on treatment of patients in the study exceeded one million Brazilian reals, totalling R$ 1,116,432.40.

Conclusion

Infection from total hip arthroplasty generates a major expense to the social security system and to the public healthcare system. Physicians must always be alert to the possible risk factors and perioperative care, striving to minimize this complication.

Development of a surgical site infection prediction model in orthopaedic trauma: The Denver Health Model

BACKGROUND

The CDC's National Healthcare Safety Network's (NHSN) current risk adjustment model for surgical site infections (SSI) following open reduction internal fixation (ORIF) of long bone fractures is a suboptimal predictor of risk. We hypothesized that by including variables known to be associated with SSI following ORIF, we would develop a model that would increase the accuracy and predictability of SSI risk.

METHODS

Patients who underwent ORIF of a long bone between January 1, 2012 and December 31, 2014 were included in the study (n=1543). Patient risk factors, injury risk factors and perioperative risk factors were considered in the development of this model. We developed a risk prediction model for SSI following ORIF and then applied this to a new dataset of ORIF to determine the expected number of infections. This was compared to the expected number of infections calculated using the NHSN risk adjusted model.

RESULTS

The final multivariate model included age (odds ratio: 1.02, p-value<0.001, 95% confidence interval: 1.00-1.04), lower leg fracture (2.63, 0.004, 1.40-4.93), open fracture (1.87, 0.07, 0.93-3.76), American Society of Anesthesiologists (ASA) (2.09, 0.02, 1.07-4.08) and history of methicillin-resistant Staphylococcus aureus (MRSA), which was the most important predictor of infection (7.20, <0.001, 2.61-19.85). The c-index was 0.74 compared to 0.65 for the NHSN model, indicating that our model more accurate in estimating infection risk. When the developed model was used to predict the number of expected infections on a new dataset from 2015, 36.3 SSI were expected compared to 5.7 calculated by the NHSN model.

CONCLUSIONS

The model that was developed uses five easily identifiable risk factors that result in a more accurate prediction of infection at our facility than the currently used model.

LEVEL OF EVIDENCE

Prognostic and epidemiologic study, level III.

What Is the Timing of General Health Adverse Events That Occur After Total Joint Arthroplasty?

BACKGROUND

Despite extensive research regarding risk factors for adverse events after total joint arthroplasty (TJA), there are few publications describing the timing at which such adverse events occur.

QUESTIONS/PURPOSES

(1) On which postoperative day do certain adverse events occur? (2) What adverse events occur earlier after TKA than after THA? (3) For each adverse event, what proportion occurred after hospital discharge?

METHODS

We screened the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) to identify all patients undergoing primary THA and primary TKA between 2005 and 2013, resulting in a study population of 124,657 patients evaluated as part of this retrospective database analysis. For each of eight different adverse events, the median postoperative day of diagnosis, interquartile range for day of diagnosis, and middle 80% for day of diagnosis were determined. Multivariate Cox proportional hazards modeling was used to test whether there is a difference of timing for each adverse event as stratified by TKA or THA. The proportion of adverse events occurring after versus before discharge was also calculated.

RESULTS

The median day of diagnosis (and interquartile range; middle 80%) for stroke was 2 (1-10; 1-19), myocardial infarction 3 (2-6; 1-15), pulmonary embolism 3 (2-7; 1-19), pneumonia 4 (2-9; 2-17), deep vein thrombosis 6 (3-14; 2-23), urinary tract infection 8 (3-16; 2-24), sepsis 10 (5-19; 2-24), and surgical site infection 17 (11-23; 6-28). For the later occurring adverse events (surgical site infection, sepsis), the rate of occurrence remained high at the end of the 30-day postoperative period. Timing was earlier in patients undergoing TKA for pulmonary embolism (day 3 [interquartile range 2-6] versus 5 [3-17], p < 0.001) and deep vein thrombosis (day 5 [2-11] versus 13 [6-22], p < 0.001). The proportion of events occurring after discharge for myocardial infarction was 97 of 283 (34%), stroke 42 of 118 (36%), pulmonary embolism 223 of 625 (36%), pneumonia 171 of 426 (40%), deep vein thrombosis 576 of 956 (60%), urinary tract infection 958 of 1406 (68%), sepsis 284 of 416 (68%), and surgical site infection 1147 of 1212 (95%).

CONCLUSIONS

As lengths of hospital stay after TJA continue to decrease, our findings suggest that caution is in order because several acute and immediately life-threatening findings, including myocardial infarction and pulmonary embolism, might occur after discharge. Furthermore, the timing of surgical site infection and sepsis suggests that even the 30-day followup afforded by the ACS-NSQIP may not be sufficient to study the latest occurring adverse events. Additionally, both pulmonary embolism and deep vein thrombosis tend to occur earlier after TKA than THA, and this should guide clinical surveillance efforts in patients undergoing those procedures. These findings also indicate that inpatient-only databases (such as the Nationwide Inpatient Sample) may fail to capture a very large proportion of postoperative adverse events, weakening the conclusions of many published studies using those databases.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Medical comorbidities and perioperative allogeneic red blood cell transfusion are risk factors for surgical site infection after shoulder arthroplasty

BACKGROUND

Multiple perioperative factors have been implicated in infection risk after shoulder arthroplasty. The purpose of this study was to determine surgical site infection (SSI) risk due to medical comorbidities or blood transfusion after primary or revision shoulder arthroplasty.

METHODS

Comprehensive data on medical comorbidities, surgical indication, perioperative transfusion, and SSI were obtained for 707 patients who underwent primary or revision hemiarthroplasty or total shoulder arthroplasty in a single hospital system. Multivariate Poisson regression was used to determine the independent association between allogeneic red blood cell transfusion, medical comorbidities, and SSI after controlling for procedure.

RESULTS

The SSI rate was 1.9% for primary hemiarthroplasties and 1.3% for primary total shoulder arthroplasties. Among patients without prior shoulder infection, revision arthroplasty or prior open reduction and internal fixation had higher SSI risk than primary arthroplasties (incidence risk ratio [IRR], 11.4; 95% confidence interval [CI], 3.84-34.0; P < .001); among primary arthroplasties, SSI risk factors included male gender (IRR, 60.0; CI, 4.39-819; P = .002), rheumatoid arthritis (IRR, 8.63; CI, 1.84-40.4; P = .006), and long-term corticosteroid use (IRR, 37.4; CI, 5.79-242; P < .001). Perioperative allogeneic red blood cell transfusion significantly increased SSI risk and was dose dependent (IRR, 1.68 per unit packed red blood cell; CI, 1.21-2.35; P = .002).

CONCLUSION

Gender, rheumatoid arthritis, and long-term (>1 year) corticosteroid use affect SSI risk after shoulder arthroplasty. Revision surgery, particularly in the setting of prior infection, increased risk of future infection. Finally, allogeneic red blood cell transfusion increases SSI risk after shoulder arthroplasty in a dose-dependent manner.

Multimodal Nutritional Management in Primary Total Knee Arthroplasty: A Randomized Controlled Trial

BACKGROUND

This study aims at evaluating the effectiveness of a new multimodal nutritional management (MNM) on albumin (ALB) transfusion, the incidence of electrolyte disorders, blood loss, perioperative levels of ALB and electrolyte, length of hospital stay (LOH), and complications in patients following total knee arthroplasty without tourniquet.

METHODS

A total of 162 patients were randomized to receive either the MNM protocol (n = 81, experimental group) or traditional protocol (n = 81, control group). The primary outcomes were the rate and amount of ALB infusion, LOH, total blood loss, maximum hemoglobin drop, allogeneic transfusion rate, and the incidence of electrolyte disorders. The secondary outcomes were levels of ALB and electrolyte at different time points and the incidence of complications.

RESULTS

The rate and amount of ALB transfusion required in MNM group were significantly lower than those in control group (P = .006, P = .021, respectively). LOH was shorter in MNM group (P < .001). Total blood loss and maximum hemoglobin drop were similar. The incidence of kaliopenia and hypocalcemia was lower in MNM group on the first postoperative day (P = .019, P = .028, respectively). Patients in MNM group had higher levels of ALB, sodium, potassium, and calcium than those in control group on the first postoperative day.

CONCLUSION

The MNM protocol can effectively low down the amount of ALB transfusion, the number of patients requiring ALB transfusion, the incidence of electrolyte disorders, and LOH following primary total knee arthroplasty without tourniquet. Patients can obtain a smaller decline in ALB, sodium, potassium, and calcium.

Risk Factors for Hospital Admission After Anterior Cruciate Ligament Reconstruction

PURPOSE

To determine patient and surgical risk factors for admission after anterior cruciate ligament reconstruction (ACLR) using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database.

METHODS

All instances of ACLR from 2005 to 2014 from the ACS NSQIP prospective database were analyzed. Both univariate analysis and binary logistic regression were performed to determine which patient demographics and medical comorbidities were associated with admission after surgery.

RESULTS

Of the 9,146 patients undergoing ACLR, 1,197 (13.1%) required admission. Univariate analysis found that the following variables were associated with the need for admission: decreased age, Hispanic ethnicity, higher American Society of Anesthesiologists class, higher Charlson Comorbidity Index, use of an epidural anesthesia, longer operative times, prior operation within 30 days, dyspnea, smoking, diabetes, chronic obstructive pulmonary disease, previous cardiac surgery, hypertension, previous revascularization procedure, and a known bleeding disorder. Independent predictors of admission on multivariate analysis included Hispanic ethnicity (odds ratio [OR] 8.9), use of epidural anesthesia (OR 6.3), known bleeding disorder (OR 4.02), increased body mass index (OR 1.03), longer operation time (OR 1.012), and younger age (OR 1.008).

CONCLUSIONS

Our study identifies Hispanic ethnicity, use of epidural anesthesia, and history of bleeding disorder as major independent risk factors for admission after ACLR.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Avascular Necrosis Is Associated With Increased Transfusions and Readmission Following Primary Total Hip Arthroplasty

Avascular necrosis (AVN) may confer an increased risk of complications and readmission following total hip arthroplasty (THA). However, current risk-adjustment models do not account for AVN. A total of 1706 patients who underwent THA for AVN from 2011 to 2013 were selected from the American College of Surgeon's National Surgical Quality Improvement Program database and matched 1:1 to controls using a predetermined propensity score algorithm. Rates of 30-day medical and surgical complications, readmissions, and reoperations were compared between cohorts. Propensity-score logistic regression was used to determine independent associations between AVN and outcomes of interest. Patients with AVN had a higher rate of medical complications than those without AVN (20.3% vs 15.3%, respectively; P<.001). Bleeding transfusion was the most common medical complication, occurring at a significantly higher rate in patients with AVN than those without AVN (19.6% vs 13.9%, respectively; P<.001). Patients with AVN were also twice as likely to experience a readmission after THA (odds ratio, 2.093; 95% confidence interval, 1.385-3.164). Avascular necrosis of the femoral head is an independent risk factor for transfusion up to 72 hours postoperatively and readmission up to 30 days following total hip replacement. [Orthopedics. 2017; 40(3):171-176.].

Vaccine development to prevent Staphylococcus aureus surgical-site infections

BACKGROUND

Staphylococcus aureus surgical-site infections (SSIs) are a major cause of poor health outcomes, including mortality, across surgical specialties. Despite current advances as a result of preventive interventions, the disease burden of S. aureus SSI remains high, and increasing antibiotic resistance continues to be a concern. Prophylactic S. aureus vaccines may represent an opportunity to prevent SSI.

METHODS

A review of SSI pathophysiology was undertaken in the context of evaluating new approaches to developing a prophylactic vaccine to prevent S. aureus SSI.

RESULTS

A prophylactic vaccine ideally would provide protective immunity at the time of the surgical incision to prevent initiation and progression of infection. Although the pathogenicity of S. aureus is attributed to many virulence factors, previous attempts to develop S. aureus vaccines targeted only a single virulence mechanism. The field has now moved towards multiple-antigen vaccine strategies, and promising results have been observed in early-phase clinical studies that supported the recent initiation of an efficacy trial to prevent SSI.

CONCLUSION

There is an unmet medical need for novel S. aureus SSI prevention measures. Advances in understanding of S. aureus SSI pathophysiology could lead to the development of effective and safe prophylactic multiple-antigen vaccines to prevent S. aureus SSI.

Low-dose dexamethasone during arthroplasty: What do we know about the risks?

Dexamethasone is commonly applied during arthroplasty to control post-operative nausea and vomiting (PONV). However, conflicting views of orthopaedic surgeons and anaesthesiologists regarding the use of dexamethasone raise questions about risks of impaired wound healing and surgical site infections (SSI).

The aim of this systematic review is to determine the level of evidence for the safety of a peri-operative single low dose of dexamethasone in hip and knee arthroplasty.

We systematically reviewed literature in PubMed, EMBASE and Cochrane databases and cited references in articles found in the initial search from 1980 to 2013 based on predefined inclusion criteria. The review was completed with a ‘pro’ and ‘con’ discussion.

After identifying 11 studies out of 104, only eight studies met the inclusion criteria. In total, 1335 patients were studied without any incidence of SSI. Causes of SSI are multifactorial. Therefore, 27 205 patients would be required (power = 90%, alpha = 0.05) to provide substantiated conclusions on safety of a single low dose of dexamethasone.

Positively, many studies demonstrated showed convincing effects of low-dose dexamethasone on prevention of PONV and dose-dependent effects on post-operative pain and quality of recovery. Dexamethasone induces hyperglycaemia, but none of the studies demonstrated a concomitant SSI.

Conversely, animal studies showed that high dose dexamethasone inhibits wound healing.

A team approach of anaesthesiologists and orthopaedic surgeons is mandatory in order to balance the risk–benefit ratio of peri-operatively applied steroids for individual arthroplasty patients.

We did not find evidence that a single low dose of dexamethasone contributes to SSI or wound healing impairment from the current studies.

Cite this article: Wegener JT, Kraal T, Stevens MF, Hollman MW, Kerkhoffs GMMJ, Haverkamp D. Low-dose dexamethasone during arthroplasty: what do we know about the risks? EFORT Open Rev 2016;1:303-309. DOI: 10.1302/2058-5241.1.000039.

Use of a Novel Pathway for Early Discharge Was Associated With a 48% Shorter Length of Stay After Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis

INTRODUCTION

Hospital stay after posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) has decreased only modestly over time despite a healthy patient population. The purpose of this study was to evaluate the impact of a novel postoperative pathway on length of stay (LOS) and complications.

METHODS

A retrospective review of patients undergoing PSF for AIS in 2011 to 2012 was performed at 2 institutions evaluating demographics, preoperative Cobb angles, surgical duration, blood loss, LOS, and postoperative complications. Patients at one center were managed using an accelerated discharge (AD) pathway emphasizing early transition to oral pain medications mobilization with physical therapy 2 to 3 times/d, and discharge regardless of return of bowel function. Expectations were set with the family before surgery for early discharge. Patients at the other center were managed without a standardized pathway.

RESULTS

One hundred five patients underwent PSF and were treated by an AD pathway, whereas 45 patients were managed using a traditional discharge (TD) pathway. There was no difference in proximal thoracic and main thoracic Cobb magnitudes and a small difference in thoracolumbar curve magnitudes (35.2±13.0 degrees AD vs. 40.6±11.4 degrees TD, P=0.004) between groups. Surgical time was slightly shorter in AD patients (median 3.1 vs. 3.9 h, P=0.0003) with no difference in estimated blood loss. LOS was 48% shorter in the AD group (2.2 vs. 4.2 d, P<0.0001). There was no difference in readmissions or wound complications between groups.

CONCLUSIONS

Hospital stay was nearly 50% shorter in patients managed by the AD pathway without any increase in readmissions or early complications.

SIGNIFICANCE

Discharge after PSF for AIS may be expedited using a coordinated postoperative pathway. No increase in complications was seen using the AD pathway. Earlier discharge may reduce health care costs and allow an earlier return to normalcy for families.

LEVEL OF EVIDENCE

Level III-case control study.

Perioperative Care of Patients With Liver Cirrhosis: A Review

The incidence of cirrhosis is rising, and identification of these patients prior to undergoing any surgical procedure is crucial. The preoperative risk stratification using validated scores, such as Child-Turcotte-Pugh (CTP) and Model for End-Stage Liver Disease, perioperative optimization of hemodynamics and metabolic derangements, and postoperative monitoring to minimize the risk of hepatic decompensation and complications are essential components of medical management. The advanced stage of cirrhosis, emergency surgery, open surgeries, old age, and coexistence of medical comorbidities are main factors influencing the clinical outcome of these patients. Perioperative management of patients with cirrhosis warrants special attention to nutritional status, fluid and electrolyte balance, control of ascites, excluding preexisting infections, correction of coagulopathy and thrombocytopenia, and avoidance of nephrotoxic and hepatotoxic medications. Transjugular intrahepatic portosystemic shunt may improve the CTP class, and semielective surgeries may be feasible. Emergency surgery, whenever possible, should be avoided.

Postoperative Hyperglycemia Can Be Safely and Effectively Controlled in Both Diabetic and Nondiabetic Patients with Use of a Subcutaneous Insulin Protocol

Background:

Postoperative hyperglycemia related to stress has been shown to be an independent risk factor for periprosthetic joint infection. In a non-intensive care, general-surgery setting, a standardized postoperative insulin protocol has been shown to decrease the rate of wound infections. We hypothesized that the use of a similar protocol is both safe and effective for controlling hyperglycemia in patients who have undergone total joint replacement.

Methods:

We performed a retrospective cohort study of 489 consecutive patients who underwent primary or revision total hip or knee arthroplasty between January 2008 and April 2013. All patients were tested with point-of-care (finger-stick) glucose determinations postoperatively and were started on a subcutaneous insulin protocol if they had postoperative stress hyperglycemia of >140 mg/dL when fasting or >180 mg/dL after meals. Insulin was discontinued when blood glucose decreased to <100 mg/dL.

Results:

Of the 489 patients, 301 (62%) qualified for the insulin protocol. Thirty-seven (17%) of the 220 patients for whom the hemoglobin A1c level was available were diabetic, and 21 (11%) of the 187 patients for whom body mass index data were available were morbidly obese (body mass index, ≥40 kg/m²). Diabetes (p < 0.001), revision surgery (p < 0.001), male sex (p = 0.0110), and obesity (including morbid obesity) (p = 0.0051) were independent factors resulting in significant glycemic elevation. A trend toward hyperglycemia occurred in younger patients but did not reach significance (p = 0.063). The glucose levels of patients in all of these groups responded well to insulin. None of the patients who were managed with the insulin experienced a periprosthetic joint infection. There were no injuries related to hypoglycemia.

Conclusions:

The findings of the present study suggest that hyperglycemia is a common link between seemingly disparate factors related to the increased prevalence of periprosthetic joint infection. The standardized subcutaneous insulin protocol was both safe and effective for the treatment of hyperglycemia for nondiabetic as well as diabetic patients. Patients who have undergone total joint replacement, especially those with revision procedures, male sex, morbid obesity, and diabetes, should be evaluated for hyperglycemia starting in the post-anesthesia care unit and should be managed with the insulin protocol when that risk is identified.

Level of Evidence:

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Outcome analysis of hip or knee arthroplasty in patients with cirrhotic liver disease

OBJECTIVE

Present helpful measures to prevent expected complications that occur in patients with liver cirrhosis undergoing arthroplasty.

METHODS

218 patients who underwent hip or knee arthroplasty were included in this study. Prognoses of patients with underlying disease of liver cirrhosis and those without are compared with measures.

RESULTS

Patients with liver cirrhosis show an increase in amount of bleeding, hospital stay and infection rate compared to those who do not.

CONCLUSION

The risk of arthroplasty on patients with liver cirrhosis is higher than normal patients. Surgeons should carefully assess all cirrhotic patients pre- and postoperatively.

Incidence, Risk Factors, and Sources of Sepsis Following Total Joint Arthroplasty

BACKGROUND

Sepsis is a rare but serious complication following total joint arthroplasty (TJA). Common sources include urinary tract infection (UTI), surgical site infection (SSI), and pneumonia. The purpose of this study is to characterize the incidence, risk factors, and sources of sepsis following TJA.

METHODS

Patients undergoing primary total hip arthroplasty or total knee arthroplasty during 2005-2013 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Independent associations were tested for using multivariate regression adjusting for baseline characteristics.

RESULTS

A total of 117,935 patients were identified (45,612 undergoing total hip arthroplasty and 72,323 undergoing total knee arthroplasty). Of these, 402 (0.34%) developed sepsis following surgery. Patients who developed sepsis had an elevated mortality rate (3.7% vs 0.1%, P < .001). Among the 402 patients who developed sepsis, 124 (31%) had concomitant UTI, 110 (27%) SSI, and 60 (15%) pneumonia. Twenty-one patients (5%) had multiple infectious sources and 129 patients (32%) had no identifiable source. Independent risk factors for sepsis included greater age, male sex, functional dependence, insulin-dependent diabetes, hypertension, chronic obstructive pulmonary disease, current smoker, and greater operative time.

CONCLUSION

These findings suggest that the rate of sepsis following TJA is about 1 in 300, and that sepsis is associated with a high risk of mortality. The most common sources of sepsis are UTI, SSI, and pneumonia, potentially accounting for at least two-thirds of cases. The information provided here can be used to guide the diagnostic workup of sepsis in patients following TJA.

Biofilm and the Role of Antibiotics in the Treatment of Periprosthetic Hip and Knee Joint Infections

An increasing demand for lower limb arthroplasty will lead to a proportionate increase in the need for revision surgery. A notable proportion of revision surgery is secondary to periprosthetic joint infections (PJI). Diagnosing and eradicating PJI can form a very difficult challenge. An important cause of PJI is the formation of a bacterial biofilm on the implant surface. Our review article seeks to describe biofilms; their definitions and formation, common causative bacteria, prophylactic and therapeutic antibiotic therapy.

Risk Factors for Wound Complications After Direct Anterior Approach Hip Arthroplasty

BACKGROUND

Previous studies have suggested that wound complications may be higher after direct anterior approach (DAA) hip arthroplasty, but, specific risk factors have not been closely examined.

METHODS

We conducted a retrospective case-control study of 651 consecutive DAA hip arthroplasty surgeries performed by 2 surgeons over a 3-year period. Outcome measures included any postoperative wound problem (including prolonged drainage, wound dehiscence, wound necrosis, suture granuloma, and superficial infection) requiring additional intervention or reoperation. Univariate odds ratios (ORs) were calculated, and multivariate logistic regression analysis was performed to determine risk correlation. Receiver operator characteristic (ROC) curves were created to determine disease predictability.

RESULTS

A total of 75 patients (11.5%) experienced wound complications requiring additional intervention, of which, 13 (1.9%) required reoperation. Multivariate regression analysis found that development of wound complications was significantly and independently associated with body mass index (BMI) 30-35 kg/m² (OR 2.05; 95% confidence interval [CI] 1.08-3.88), BMI 35-40 kg/m² (OR 3.40; 95% CI 1.42-8.26), BMI > 40 kg/m² (OR 7.28; 95% CI 2.55-20.78), and diabetes mellitus (OR 2.97; 95% CI 1.46-6.07). Reoperation for wound complication was significantly associated with BMI > 40 kg/m² (OR 5.68; 95% CI 1.17-27.48) and diabetes mellitus (OR 13.08; 95% CI 3.97-43.11). Optimal cutoff values for BMI were found through receiver operator characteristic curve analysis to be 28.0 kg/m² for development of wound complications and 28.2 kg/m² for reoperation for wound complications.

CONCLUSION

Obesity and diabetes mellitus are significantly associated with postoperative wound-healing complications and the need for reoperation for these wound complications after DAA hip arthroplasty.

Superficial wound infection does not cause inferior clinical outcome after TKA

PURPOSE

Superficial wound infections do not lead to chronic prosthetic joint infection. Therefore, it has been hypothesized that a superficial infection of a surgical wound following a successfully treated TKA does not lead to a lower functional outcome at long-term follow-up. This may be due to early diagnosis and proper treatment without interrupting the rehabilitation programme. The purpose of this study was to support the hypothesis by comparing the functional outcome and health-related quality of life (HRQoL) of superficial infections treated successfully after primary total knee arthroplasty (TKA).

METHODS

In a 3000 prospective TKA cohort, 45 superficial infections were compared to a control group of 629 TKA without complications. The functional outcome, health quality, expectations and revision rate were compared between the study and control groups.

RESULTS

The groups were comparable in terms of demographic values and preoperative scores. The mean follow-up was 74.57 months (SD ± 7.1). No statistical differences were observed relative to functional outcomes at the final follow-up as measured with the Knee Society Score (156.9 vs 168.4; n.s) and range of motion (0.2-114.4 vs 0.7-112.3; n.s). For the HRQoL, no differences in the physical (40.0 vs 40.6; n.s) and mental (43.2 vs 45.8; n.s) SF-36 scores were found. Neither were there differences in post-operative expectations and the revision rate.

CONCLUSIONS

In a long-term follow-up, a different clinical outcome and HRQoL were not obtained after a successfully treated superficial infection following a TKA when compared to a TKA without complications. Based on the findings of the study, additional complications are not anticipated after a successfully treated superficial wound infection in TKA. Therefore, a different follow-up to that of a non-complicated TKA is not recommended when the early post-operative superficial wound infection has been appropriately treated. A superficial infection successfully treated in the acute post-operative period should be considered solved at long-term follow-up.

LEVEL OF EVIDENCE

Therapeutic study, Level III.

Development and Validation of a Preoperative Surgical Site Infection Risk Score for Primary or Revision Knee and Hip Arthroplasty

BACKGROUND

Surgical site infection (SSI) is a major complication following total joint arthroplasty. Host susceptibility to infection has emerged as an important predictor of SSI. The purpose of this study was to develop and validate a preoperative SSI risk-assessment tool for primary or revision knee and hip arthroplasty.

METHODS

Data for 6,789 patients who underwent total joint arthroplasty (from the years 2000 to 2011) were obtained from a single hospital system. SSI was defined as a superficial infection within 30 days or deep infection within 1 year. Logistic regression modeling was utilized to create a risk scoring system for a derivation sample (n = 5,789; 199 SSIs), with validation performed on a hold-out sample (a subset of observations chosen randomly from the initial sample to form a testing set; n = 1,000; 41 SSIs).

RESULTS

On the basis of logistic regression modeling, we created a scoring system to assess SSI risk (range, 0 to 35 points) that is the point sum of the following: primary hip arthroplasty (0 points); primary knee (1); revision hip (3); revision knee (3); non-insulin-dependent diabetes (1); insulin-dependent diabetes (1.5); chronic obstructive pulmonary disease (COPD) (1); inflammatory arthropathy (1.5); tobacco use (1.5); lower-extremity osteomyelitis or pyogenic arthritis (2); pelvis, thigh, or leg traumatic fracture (2); lower-extremity pathologic fracture (2.5); morbid obesity (2.5); primary bone cancer (4); reaction to prosthesis in the last 3 years (4); and history of staphylococcal septicemia (4.5). The risk score had good discriminatory capability (area under the ROC [receiver operating characteristic] curve = 0.77) and calibration (Hosmer-Lemeshow chi-square test, p = 0.34) and was validated using the independent sample (area under the ROC curve = 0.72). A small subset of patients (5.9%) had a >10% estimated infection risk.

CONCLUSIONS

The patient comorbidities composing the risk score heavily influenced SSI risk for primary or revision knee and hip arthroplasty. We believe that infection risk can be objectively determined in a preoperative setting with the proposed SSI risk score.

Same-Day Surgery Does Not Increase Deep Infection Risk in Bilateral Total Hip Arthroplasty Patients

BACKGROUND

Patients with bilateral hip disease may undergo same-day or staged bilateral total hip arthroplasty (THA). Our purpose was to compare the odds and identify risk factors for deep periprosthetic joint infection (PJI) among patients undergoing same-day vs staged bilateral THA (within 1 year or more than 1 year apart).

METHODS

Administrative data for patients subjected to same-day and staged bilateral THA between January 1999 and December 2013 were retrieved. Patients with subsequent PJI were identified. Mean follow-up was 112.6 months (range, 23-201). A logistic regression model was constructed to determine differences in odds for infection between groups and risk factors for PJI.

RESULTS

We identified 1808 patients treated with same-day bilateral THA, 2082 patients treated with staged THAs within 1 year, and 2760 patients treated with staged THAs more than 1 year apart. Patients treated with same-day procedures had similar odds for PJI compared to those treated with staged THAs within 1 year (odds ratio [OR] = 0.632, 95% confidence interval [CI] [0.203, 1.962]), or more than 1 year apart (OR = 1.391, 95% CI [0.516, 3.746]). Women had 66.1% lower odds for PJI than men (OR = 0.339, 95% CI [0.16, 0.72]). Patients with inflammatory arthritis had 632% higher odds for PJI than patients with degenerative arthritis (OR = 7.321, 95% CI [1.912, 28.028]). Allogeneic transfusion was associated with 166% higher odds for PJI (OR = 2.661, 95% CI [1.198, 5.911]).

CONCLUSION

Same-day bilateral THA is not associated with increased odds for PJI compared to staged procedures. Male gender, inflammatory etiology, and allogeneic transfusion are significant risk factors for PJI in patients undergoing same-day or staged bilateral THA.

A Trend for Increased Risk of Revision Surgery due to Deep Infection following Fast-Track Hip Arthroplasty

Rates of revision surgery due to deep infection following total hip arthroplasty (THA) increased at a Norwegian hospital following implementation of fast-track procedures. The purpose of this study was to determine whether selected demographic (age and sex) and clinical (body mass index, American Society of Anesthesiologists (ASA) classification, surgery duration, length of hospital stay, cemented versus uncemented prosthesis, and fast-track procedures) factors were associated with higher risk of revision surgery due to deep infection following THA. In a prospective designed study 4,406 patients undergoing primary THA between January 2001 and January 2013 where included. Rates of infection-related revision surgery within 3 months of THA were higher among males and among patients who received fast-track THA. Adjusting for sex and age, the implemented fast-track elements were significantly associated with increased risk of revision surgery. Risk of infection-related revision surgery was unrelated to body mass index, physical status, surgery duration, length of hospital stay, and prosthesis type. Because local infiltration analgesia, drain cessation, and early mobilization were introduced in combination, it could not be determined which component or combination of components imposed the increased risk. The findings in this small sample raise concern about fast-track THA but require replication in other samples.

Renal and Gastrointestinal Considerations in Patients Undergoing Elective Orthopaedic Surgery

To minimize perioperative complications after orthopaedic procedures, patients may undergo medical optimization, which includes an assessment of their renal function and gastrointestinal (GI) system. The GI and renal systems are complex, and their proper optimization in the preoperative period can influence the success of any procedure. Several factors can prevent complications and reduce morbidity, mortality, and the cost of care, including a thorough evaluation and screening, with particular emphasis on anemia and its renal and GI causes; management of medications that are metabolized by the liver and excreted by the kidneys; and careful attention to the patient's nutritional status.

Hypoalbuminemia More Than Morbid Obesity is an Independent Predictor of Complications After Total Hip Arthroplasty

Health care reform is directing clinical practice towards improving outcomes and minimizing complications. Preoperative identification of high-risk patients and modifiable risk factors present opportunity for clinical research. A total of 49,475 total hip arthroplasty patients were identified from National Surgical Quality Improvement Program between 2006 and 2013. We compared morbidly obese patients (BMI≥40 kg/m(2)) and non-morbidly obese patients (BMI 18.5-40 kg/m(2)). We also compared patients with hypoalbuminemia (serum albumin <3.5 g/dL) against those with normal albumin. Our study demonstrates that hypoalbuminemia is a significant risk factor for mortality and major morbidity among total hip arthroplasty patients, while morbid obesity was only associated with an increased risk of superficial surgical site infection. Impressively, hypoalbuminemia patients carried a 5.94-fold risk of 30-day mortality.

Risk factors for periprosthetic joint infection in total knee arthroplasty

PURPOSE

To evaluate the incidence and risk factors of periprosthetic joint infection (PJI) in patients undergoing total knee arthroplasty (TKA) in a high-volume hospital.

METHODS

Records of 1133 primary TKAs were reviewed. Correlation between surgery volume and infection rate was determined. Risk factors for PJI were identified using case-control analysis of variables. TKAs performed between October 2012 and March 2013 without infection were used as controls.

RESULTS

Of 1133 TKAs, 8 (0.71%) PJI occurred. The organisms involved were Staphylococcus aureus (n=4), coagulase-negative staphylococci (n=2), Pseudomonas aeruginosa (n=1), and methicillin-resistant S aureus (n=1). In the 6-month period chosen as the control period, one (0.52%) out of 192 TKAs developed PJI. Hospital annual volume did not correlate with infection rate (p=0.766). Significant risk factors included young age, comorbidities such as diabetes, anaemia, thyroid disease, heart disease, lung disease, and long operating time. Six of the 8 patients with PJIs had at least one risk factor. However, the number of patients with infection was too small to have sufficient power.

CONCLUSION

Comorbidities are a risk factor for PJI. Perioperative optimisation of comorbidities and the use of antibiotic-loaded cement in patients with severe comorbidities should be considered.

Costs Associated With Surgical Site Infections in Veterans Affairs Hospitals

IMPORTANCE

Surgical site infections (SSIs) are potentially preventable complications that are associated with excess morbidity and mortality.

OBJECTIVE

To determine the excess costs associated with total, deep, and superficial SSIs among all operations and for high-volume surgical specialties.

DESIGN, SETTING, AND PARTICIPANTS

Surgical patients from 129 Veterans Affairs (VA) hospitals were included. The Veterans Health Administration Decision Support System and VA Surgical Quality Improvement Program databases were used to assess costs associated with SSIs among VA patients who underwent surgery in fiscal year 2010.

MAIN OUTCOMES AND MEASURES

Linear mixed-effects models were used to evaluate incremental costs associated with SSIs, controlling for patient risk factors, surgical risk factors, and hospital-level variation in costs. Costs of the index hospitalization and subsequent 30-day readmissions were included. Additional analysis determined potential cost savings of quality improvement programs to reduce SSI rates at hospitals with the highest risk-adjusted SSI rates.

RESULTS

Among 54,233 VA patients who underwent surgery, 1756 (3.2%) experienced an SSI. Overall, 0.8% of the cohort had a deep SSI, and 2.4% had a superficial SSI. The mean unadjusted costs were $31,580 and $52,620 for patients without and with an SSI, respectively. In the risk-adjusted analyses, the relative costs were 1.43 times greater for patients with an SSI than for patients without an SSI (95% CI, 1.34-1.52; difference, $11,876). Deep SSIs were associated with 1.93 times greater costs (95% CI, 1.71-2.18; difference, $25,721), and superficial SSIs were associated with 1.25 times greater costs (95% CI, 1.17-1.35; difference, $7003). Among the highest-volume specialties, the greatest mean cost attributable to SSIs was $23,755 among patients undergoing neurosurgery, followed by patients undergoing orthopedic surgery, general surgery, peripheral vascular surgery, and urologic surgery. If hospitals in the highest 10th percentile (ie, the worst hospitals) reduced their SSI rates to the rates of the hospitals in the 50th percentile, the Veterans Health Administration would save approximately $6.7 million per year.

CONCLUSIONS AND RELEVANCE

Surgical site infections are associated with significant excess costs. Among analyzed surgery types, deep SSIs and SSIs among neurosurgery patients are associated with the highest risk-adjusted costs. Large potential savings per year may be achieved by decreasing SSI rates.

Hospital Length of Stay following Primary Total Knee Arthroplasty: Data from the Nationwide Inpatient Sample Database

Demand and cost of total knee arthroplasty (TKA) has increased significantly over the past decade resulting in decreased hospital length of stay (LOS) to counterbalance increasing cost of health care. The purpose of this study was to determine the factors that influence LOS following primary TKA. Discharge data from the 2009-2011 Nationwide Inpatient Sample were used. Patients included underwent primary TKA and were grouped based on LOS; 3 days or less, and 4 days or more. Majority of patients had a hospital LOS of 3 or less (74.8%). The most significant predictors of increased hospital LOS (≥ 4 days) were age ≥ 80 years, Hispanic race, Medicaid payer status, lower median household income, weekend admission, rural non-teaching hospital, discharge to another facility and any complication.

Burden of Surgical Site Infections Associated with Arthroplasty and the Contribution of Staphylococcus aureus

BACKGROUND

Patients undergoing arthroplasty are at considerable risk of experiencing post-operative complications, including surgical site infections (SSIs). In addition to potential economic consequences, SSIs can have a negative impact on patient outcomes and may potentially be life-threatening. Staphylococcus aureus has been consistently shown as the leading cause of SSIs associated with orthopedic surgery, with an important contribution from methicillin-resistant S. aureus (MRSA). This study evaluated the global burden of SSIs among patients undergoing orthopedic surgical procedures, and specifically those undergoing knee and hip arthroplasties.

METHODS

An extensive search of PubMed and recent conference proceedings was conducted. English articles published between 2003 and 2013 pertaining to SSI epidemiology, patient outcomes, and healthcare resource utilization and costs were reviewed.

RESULTS

Overall, 81 studies were included, mainly from North America and Europe. Median SSI and S. aureus SSI rates, calculated as percentage of all arthroplasty procedures, were 1.7% (range: 0.25%-4.4%; 15 studies) and 0.6% (range: 0.1%-23%), respectively. Median SSI rates were 1.3% (range: 0.05%-19%; 22 studies) after knee arthroplasty, and 2.1% (range: 0.05%-28%; 24 studies) after hip arthroplasty. S. aureus SSI rates ranged from 0.2%-2.4% and 0.18%-3.8% for patients undergoing knee and hip arthroplasty, respectively. The percentage of S. aureus SSIs because of MRSA varied widely within each patient category. SSI-related mortality data (14 studies) showed that in-hospital mortality rates were low (1.2%-2.5%), but increased with time after index arthroplasty procedure (up to 56% over 1 y). Studies assessing healthcare resource utilization (n = 21) revealed that developing post-orthopedic SSIs resulted in a two- to three-fold increase in length of hospital stay (LOS) compared with non-infected patients (median LOS: 18.9 d vs. 6 d for non-SSI patients). Patients with SSIs because of methicillin-resistant staphylococci incurred greater mean LOS compared with SSIs because of methicillin-sensitive organisms. Readmission rates reported in 11 studies indicate a greater likelihood in the presence of SSIs; comparison across studies was not feasible because of differences in data reporting. Consistent with increased healthcare resource utilization (LOS and readmission) associated with SSIs, cost studies (n = 23) revealed that the presence of SSIs was associated with up to three-fold cost increase compared with the absence of SSI across all orthopedic patient categories assessed.

CONCLUSIONS

SSIs are associated with increased morbidity, mortality rates, healthcare resource utilization, and costs. Despite the relatively low SSI incidence following orthopedic surgery and specifically arthroplasty, preventive methods, specifically those targeting S. aureus, would serve to minimize costs and improve patient outcomes.

Risk Factors for Recurrence of Periprosthetic Knee Infection

We retrospectively reviewed 110 patients who underwent two-stage revision surgery in order to identify potential risk factors for recurrence of periprosthetic infection. We found that patients with inflammatory arthritis (P=0.0125), perioperative hematoma formation (P=0.0422), wound dehiscence (P=0.042), and those who are chronic Staphylococcus carriers (P=0.0177) were associated with an increased incidence of re-infection. The duration of intravenous antibiotic therapy less than 6 weeks was associated with a reduced risk of reinfection to greater than 6 weeks (P=0.03). Multivariate analysis indicated that wound dehiscence (odds ratio [OR], 5.119; 95% confidence interval [CI], 1.367-19.17), and Staphylococcus carriers (OR, 11.419; 95% CI, 1.376-94.727) are significant predictors of recurrence (P=0.0153 and 0.0241, respectively).

The Incidence of and Risk Factors for 30-Day Surgical Site Infections Following Primary and Revision Total Joint Arthroplasty

The authors assessed the incidence of and risk factors associated with 30-day surgical site infections (SSIs) following primary (p) and revision (r) THA and TKA. In total, 23,128 primary and 2170 revision TJAs were identified between 2005 and 2010 in the ACS NSQIP database. The 30-day SSI rates, overall and deep, were 1.1 and 0.1% for pTKA, 1.18 and 0.4% for pTHA, 1.68 and 0.7% for rTKA, and 2.9 and 1.7% for rTHA. After primary TJA, independent risk factors were BMI>40, hypertension, prolonged operative time, electrolyte disturbance and previous infection, and after revision TJA, dyspnea and bleeding disorder were risk factors. This study should help provide benchmark data for SSI following TJA.

Staphylococcus aureus infections following knee and hip prosthesis insertion procedures

Background

Staphylococcus aureus is the most common and most important pathogen following knee and hip arthroplasty procedures. Understanding the epidemiology of invasive S. aureus infections is important to quantify this serious complication.

Methods

This nested retrospective cohort analysis included adult patients who had undergone insertion of knee or hip prostheses with clean or clean-contaminated wound class at 11 hospitals between 2003–2006. Invasive S. aureus infections, non-superficial incisional surgical site infections (SSIs) and blood stream infections (BSIs), were prospectively identified following each procedure. Prevalence rates, per 100 procedures, were estimated.

Results

13,719 prosthetic knee (62%) and hip (38%) insertion procedures were performed. Of 92 invasive S. aureus infections identified, SSIs were more common (80%) than SSI and BSI (10%) or BSI alone (10%). The rate of invasive S. aureus infection/100 procedures was 0.57 [95% CI: 0.43-0.73] for knee insertion and 0.83 [95% CI: 0.61-1.08] for hip insertion. More than half (53%) were methicillin-resistant. Median time-to-onset of infection was 34 and 26 days for knee and hip insertion, respectively. Infection was associated with higher National Healthcare Safety Network risk index (p ≤ 0.0001).

Conclusions

Post-operative invasive S. aureus infections were rare, but difficult-to-treat methicillin-resistant infections were relatively common. Optimizing preventative efforts may greatly reduce the healthcare burden associated with S. aureus infections.

Patient, Surgery, and Hospital Related Risk Factors for Surgical Site Infections following Total Hip Arthroplasty

Surgical site infections (SSI) following total hip arthroplasty (THA) have a significantly adverse impact on patient outcomes and pose a great challenge to the treating surgeon. Therefore, timely recognition of those patients at risk for this complication is very important, as it allows for adopting measures to reduce this risk. This review discusses literature reported risk factors for SSI after THA. These can be classified into patient-related factors (age, gender, obesity, comorbidities, history of infection, primary diagnosis, and socioeconomic profile), surgery-related factors (allogeneic blood transfusion, DVT prophylaxis and coagulopathy, duration of surgery, antibiotic prophylaxis, bearing surface and fixation, bilateral procedures, NNIS index score, and anesthesia type), and hospital-related factors (duration of hospitalization, institution and surgeon volume, and admission from a healthcare facility). All these factors are discussed with respect to potential measures that can be taken to reduce their effect and consequently the overall risk for infection.

Inpatient surgical site infection after shoulder arthroplasty

BACKGROUND

Surgical site infection (SSI) after joint arthroplasty is associated with prolonged hospitalization, reoperation, inferior outcomes, and substantial resource utilization. As the number of shoulder replacements performed in the United States continues to rise, measuring the incidence of inpatient SSI after hemiarthroplasty (HSA) and total shoulder arthroplasty (TSA), and associated risk factors for infection is worthwhile.

METHODS

Using the Nationwide Inpatient Sample (NIS), we reviewed 241,193 patients undergoing TSA or reverse TSA and 159,795 undergoing HSA between 2002 and 2011 and identified patients with an associated diagnosis of SSI during the admission. Demographic characteristics, preoperative diagnoses, further surgical procedures, associated comorbidities, and in-hospital events associated with SSI were sought in multivariable logistic regression analysis.

RESULTS

An in-hospital SSI developed in 0.08% of patients undergoing TSA or reverse TSA and in 0.11% of patients undergoing HSA. Independent risk factors for inpatient SSI included TSA vs HSA (odds ratio [OR], 1.83), Medicaid insurance vs private insurance (OR, 3.93), diagnosis of fracture nonunion (OR, 5.76), avascular necrosis (OR 2.71), or proximal humeral fracture (OR, 2.62) vs primary osteoarthritis, comorbidities, in-hospital events (blood transfusion, pneumonia, and acute renal failure), and increased duration of hospital stay.

CONCLUSIONS

The small percentage of SSI that occurs during the initial inpatient stay after shoulder arthroplasty is related to diagnoses other than primary osteoarthritis in more infirm patients with low-income government insurance (Medicaid). Patients considering shoulder arthroplasty can use this information to help decide between the potential improvement in comfort and function of the shoulder and the potential for major adverse events such as infection.

Epidemiology and burden of prosthetic joint infections

Whilst improvements in patient care have reduced the risk of infection in patients undergoing prosthetic joint surgery, the substantial and growing number of hip and knee arthroplasty procedures undertaken translates into a continued and potentially increasing burden on patients, healthcare providers and the wider economy. Increases in patient obesity will raise further challenges to prevention efforts given the associated elevated risk of infection. Ongoing monitoring of infection rates remains a critical means to identify and address local and national changes in the epidemiology of prosthetic joint infection and to assess the impact of interventions.