Perioperative Complications and Length of Stay After Revision Total Hip and Knee Arthroplasties: An Analysis of the NSQIP Database

Postoperative Medical Complications and Intermediate Care Unit/Intensive Care Unit Admission in Joint Replacement Surgery: A Prospective Risk Model

BACKGROUND

Postoperative complications are the main consumers of technical, medical, and human resources. Especially in the field of elective joint replacement surgery, a specialized, easy-to-obtain, and cost-efficient preoperative stratification and risk-estimation model is missing.

METHODS

With preoperatively surveyed patient parameters, we identified the most relevant parameters to predict postoperative medical complications. We devised a prospective risk model, measuring the individual probability for intermediate care unit (IMC) or intensive care unit (ICU) admission. The study includes all patients (n = 649) treated with primary or revision total knee arthroplasty in our clinic from 2008 to 2012.

RESULTS

The association between general comorbidity scores and mortality risk is well known. Among different comorbidity scores, the Charlson Comorbidity Index is not only relevant for overall postoperative complications (odds ratios [OR] = 2.20) but also predictive of specific complications such as the postoperative need for blood transfusion (OR = 1.94) and unexpected adverse events (OR = 1.74). Considering adverse events, c-reactive protein and leukocyte levels are also highly relevant. Upon predicting a necessary postoperative transfer to an IMC or ICU, the preoperative hemoglobin level, the Charlson Comorbidity Index, and the Index of Coexistent Disease stood out. The latter indicates an increased rate for an IMC/ICU stay by 341% per point. Condensing the most influential predictors, the probability for postoperative IMC/ICU transfer can be calculated for each individual patient. Using the routinely assessed patient's variables, no steadier prediction is possible.

CONCLUSION

The introduced risk-estimation model offers a specialized preoperative resource-stratification method in knee joint replacement surgery. It condenses the most influential, individual risk factors to avoid clinical test redundancy and improve resource efficiency and presurgical care planning. A prospective follow-up study could help validating the risk model in clinical routine.

The effect of operative time on in-hospital length of stay in revision total knee arthroplasty

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<0.01). An analysis of operative times showed positive correlations with young age, BMI greater than 30 and male sex (P<0.05). The mean LOS of revision TKA patients was found to increase with increasing operative time in 30-minute intervals (P<0.001). Multivariate analysis showed that longer operative times had significant associations with longer LOS even after adjusting for patient factors (β=0.102, SE =0.001, P<0.001). These results also showed that out of all of the study covariates, operative times had the greatest effect on LOS after revision TKA.

Conclusions

Revision TKA is a complex procedure, often requiring increased operative times compared to primary TKA. This study provides unique insight by correlating operative times to LOS in over 10,000 revision TKAs from a nationwide database. Our results demonstrate that out of all the study covariates (age, sex, and BMI), operative times had the greatest effect on LOS. The results from this study indicate that less time spent in the operating room can lead to shorter LOS for revision TKA patients. This relationship further underscores the need for improved preoperative planning and intra-operative efficiency in an effort to decrease LOS and improve patient outcomes.

Cemented conical stems can be removed more easily than cylindrical stems, regardless of cone angle in revision knee arthroplasty

BACKGROUND

According to literature, more than 30% of revised knee arthroplasties will require at least one re-revision. Practical experience has shown that there are considerable product-specific differences in the explantability of cemented long-stem prostheses. In the registers of successful implants, stem geometry varies considerably between the manufacturers. However, comparative data on explantability of the respective stems are missing. Objective of the present study was to identify a correlation between the geometry of a smooth cemented long stem and the necessary explantation energy required until failure of the implant-cement interface occurs.

METHODS

Eight cemented stems with different conical profile angles (0°-3°) were explanted in a reproducible biomechanical setup each six times to evaluate the correlation between the stem design and the required explantation energy.

RESULTS

The average explantation energy was highest in the case of the cylindrical stem, at 18.1 ± 3.6 J. At a cone angle of 0.25°, it was just 12.1 ± 2.1 J (p < 0.001) and dropped beyond 0.5° to an average of 5.7 ± 1.8 J (p < 0.001). Between 0.5° and 3°, no significant difference in the required extraction energy was observed.

CONCLUSIONS

Whereas smooth conical stems can mostly be removed easily, an early decision in favour of osteotomy or fenestration can be taken in the case of cylindrical cemented stems.

Risk Adjustment Is Necessary in Value-based Outcomes Models for Infected TKA

BACKGROUND

The Medicare Access and CHIP Reauthorization Act of 2015 provides the framework to link reimbursement for providers based on outcome metrics. Concerns exist that the lack of risk adjustment for patients undergoing revision TKA for an infection may cause problems with access to care.

QUESTIONS/PURPOSES

(1) After controlling for confounding variables, do patients undergoing revision TKA for infection have higher 30-day readmission, reoperation, and mortality rates than those undergoing revision TKA for aseptic causes? (2) Compared with patients undergoing revision TKA who are believed not to have infections, are patients undergoing revision for infected TKAs at increased risk for complications?

METHODS

We queried the American College of Surgeons National Surgical Quality Improvement Program database for patients undergoing revision TKA from 2012 to 2015 identified by Current Procedural Terminology (CPT) codes 27486, 27487, and 27488. Of the 10,848 patients identified, four were excluded with a diagnosis of malignancy (International Classification of Diseases, 9th Revision code 170.7, 170.9, 171.8, or 198.5). This validated, national database records short-term outcome data for inpatient procedures and does not rely on administrative coding data. Demographic variables, comorbidities, and outcomes were compared between patients believed to have infected TKAs and those undergoing revision for aseptic causes. A multivariate logistic regression analysis was performed to identify independent factors associated with complications, readmissions, reoperations, and mortality.

RESULTS

After controlling for demographic factors and medical comorbidities, TKA revision for infection was independently associated with complications (odds ratio [OR], 3.736; 95% confidence interval [CI], 3.198-4.365; p < 0.001), 30-day readmission (OR, 1.455; 95% CI, 1.207-1.755; p < 0.001), 30-day reoperation (OR, 1.614; 95% CI, 1.278-2.037; p < 0.001), and 30-day mortality (OR, 3.337; 95% CI, 1.213-9.180; p = 0.020). Patients with infected TKA had higher rates of postoperative infection (OR, 3.818; 95% CI, 3.082-4.728; p < 0.001), renal failure (OR, 36.709; 95% CI, 8.255-163.231; p < 0.001), sepsis (OR, 7.582; 95% CI, 5.529-10.397; p < 0.001), and septic shock (OR, 3.031; 95% CI, 1.376-6.675; p = 0.006).

CONCLUSIONS

Policymakers should be aware of the higher rate of mortality, readmissions, reoperations, and complications in patients with infected TKA. Without appropriate risk adjustment or excluding these patients all together from alternative payment and quality reporting models, fewer providers will be incentivized to care for patients with infected TKA.

LEVEL OF EVIDENCE

Level III, therapeutic study.

The Impact of Chronic Obstructive Pulmonary Disease on Postoperative Outcomes in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) utilization is increasing in older Americans. The incidence of chronic obstructive pulmonary disease (COPD) has been steadily rising over the past few decades. In particular, COPD is being increasingly more common in patients undergoing revision TKA. The aim of this study is to identify the impact of COPD on postoperative complications for patients undergoing revision TKA.

METHODS

A retrospective cohort study was conducted using data collected through the American College of Surgeons National Quality Improvement Program Database. All patients who underwent revision TKA between 2007 and 2014 were identified and stratified into groups based on COPD status. The incidence of adverse events after surgery was evaluated with univariate and multivariate analyses where appropriate.

RESULTS

Patients with COPD were found to develop more postoperative complications, including deep wound infection, organ infection, wound dehiscence, pneumonia, reintubation, renal insufficiency, urinary tract infection, myocardial infarction, sepsis, and death. Patients with COPD were also shown to have to return back to the operating room and have an extended length of hospital stay. COPD was shown to be an independent risk factor for development of wound dehiscence, pneumonia, reintubation, renal insufficiency, and renal failure. Finally, COPD was identified as an independent risk factor for unplanned return to the operating room.

CONCLUSION

Patients with COPD have greater risk for postoperatively developing wound dehiscence, pneumonia, reintubation, renal insufficiency, and renal failure complications than those without COPD. While risks for independent complications remain relatively low, consideration of COPD status is an important factor to consider when selecting surgical candidates and preoperative risk assessment.

What is the Impact of Smoking on Revision Total Hip Arthroplasty?

BACKGROUND

There is a paucity of literature evaluating the impact of smoking on revision total hip arthroplasty (THA) outcomes. The purpose of this study was to identify the effect of smoking on complications after revision THA.

METHODS

We queried the American College of Surgeons National Surgical Quality Improvement Program database to identify patients who underwent revision THA between 2006 and 2014. Patients were divided into current smokers and nonsmokers. Each cohort was compared in terms of demographics, preoperative comorbidities, and operative time. Multivariate logistic regression analysis was utilized. Adjusted odds ratios (OR) for the outcomes of any wound complication, deep infection, and reoperation within 30 days of revision THA were calculated.

RESULTS

In total, 8237 patients had undergone a revision THA. Of these patients, 14.7% were current smokers and 85.3% were nonsmokers. Univariate analyses demonstrated that smokers had a higher rate of any wound complication (4.1% vs 3.0%, P = .04), deep infection (3.2% vs 1.9%, P = .003), and reoperation (6.8% vs 4.8%, P = .003). Multivariate analysis controlling for confounding demographic, comorbidity, and operative variables identified current smokers as having a significantly increased risk of deep infection (OR, 1.58; 95% CI, 1.04-2.38) and reoperation (OR, 1.37; 95% CI, 1.03-1.85).

CONCLUSION

Smoking significantly increases the risk of infection and reoperation after revision THA. The results are even more magnified for revision procedures compared to published effects of smoking on primary THA complications. Further research is needed regarding the impact of smoking cessation on mitigation of these observed risks.

Treatments of Missing Values in Large National Data Affect Conclusions: The Impact of Multiple Imputation on Arthroplasty Research

BACKGROUND

Despite the advantages of large, national datasets, one continuing concern is missing data values. Complete case analysis, where only cases with complete data are analyzed, is commonly used rather than more statistically rigorous approaches such as multiple imputation. This study characterizes the potential selection bias introduced using complete case analysis and compares the results of common regressions using both techniques following unicompartmental knee arthroplasty.

METHODS

Patients undergoing unicompartmental knee arthroplasty were extracted from the 2005 to 2015 National Surgical Quality Improvement Program. As examples, the demographics of patients with and without missing preoperative albumin and hematocrit values were compared. Missing data were then treated with both complete case analysis and multiple imputation (an approach that reproduces the variation and associations that would have been present in a full dataset) and the conclusions of common regressions for adverse outcomes were compared.

RESULTS

A total of 6117 patients were included, of which 56.7% were missing at least one value. Younger, female, and healthier patients were more likely to have missing preoperative albumin and hematocrit values. The use of complete case analysis removed 3467 patients from the study in comparison with multiple imputation which included all 6117 patients. The 2 methods of handling missing values led to differing associations of low preoperative laboratory values with commonly studied adverse outcomes.

CONCLUSION

The use of complete case analysis can introduce selection bias and may lead to different conclusions in comparison with the statistically rigorous multiple imputation approach. Joint surgeons should consider the methods of handling missing values when interpreting arthroplasty research.

Aseptic revision total hip arthroplasty in the elderly

Aims

The aim of this study was to compare the rate of perioperative complications following aseptic revision total hip arthroplasty (THA) in patients aged ≥ 80 years with that in those aged < 80 years, and to identify risk factors for the incidence of serious adverse events in those aged ≥ 80 years using a large validated national database.

Patients and Methods

Patients who underwent aseptic revision THA were identified in the 2005 to 2015 National Surgical Quality Improvement Program (NSQIP) database and stratified into two age groups: those aged < 80 years and those aged ≥ 80 years. Preoperative and procedural characteristics were compared. Multivariate regression analysis was used to compare the risk of postoperative complications and readmission. Risk factors for the development of a serious adverse event in those aged ≥ 80 years were characterized.

Results

The study included 7569 patients aged < 80 years and 1419 were aged ≥ 80 years. Multivariate analysis showed a higher risk of perioperative mortality, pneumonia, urinary tract infection and the requirement for a blood transfusion and an extended length of stay in those aged ≥ 80 years compared with those aged < 80 years. Independent risk factors for the development of a serious adverse event in those aged ≥ 80 years include an American Society of Anesthesiologists score of ≥ 3 and procedures performed under general anaesthesia.

Conclusion

Even after controlling for patient and procedural characteristics, aseptic revision THA is associated with greater risks in patients aged ≥ 80 years compared with younger patients. This is important for counselling and highlights the need for medical optimization in these vulnerable patients. Cite this article: Bone Joint J 2018;100-B:143–51.

Revision Total Shoulder Arthroplasty is Associated with Increased Thirty-Day Postoperative Complications and Wound Infections Relative to Primary Total Shoulder Arthroplasty

BACKGROUND

With an increasing volume of primary total shoulder arthroplasties (TSA), the number of revision TSA cases is expected to increase as well. However, the postoperative medical morbidity of revision TSA has not been clearly described.

QUESTIONS/PURPOSES

The purpose of this study was to determine the rate of postoperative complications following revision TSA, relative to primary TSA. In addition, we sought to identify independent predictors of complications, as well as to compare operative time and postoperative length of stay between primary and revision TSA.

METHODS

Patients who underwent primary/revision TSA between 2005 and 2015 were identified in the American College of Surgeons National Surgical Quality Improvement Program. Differences in complications, readmission rates, operative time, length of stay, and predictors of complications were evaluated using bivariate and multivariate analyses.

RESULTS

A total of 10,371 primary TSA (95.4%) and 496 revision TSA cases (4.6%) were identified. The overall complication rate was 6.5% in primary and 10.7% in revision TSA patients (p < 0.001). Multivariate analysis identified an increased risk of any complication (odds ratio 1.73, p < 0.001), major complication (2.08, p = 0.001), and wound infection (3.45, p = 0.001) in revision TSA patients, relative to primary cases. Operative time was increased in revision cases (mean ± standard deviation, 125 ± 62.5), relative to primary (115 ± 47.7, p < 0.001). Age > 75, female sex, history of diabetes or chronic obstructive pulmonary disease, and American Society of Anesthesiologists classification ≥ 3 were associated with increased risk of any complication. Smoking history was the only significant predictor of wound infection.

CONCLUSION

Revision TSA, in comparison to primary, poses an increased risk of postoperative complications, particularly wound infections. A history of smoking was an independent predictor of wound infections.

Recording Adverse Events Following Joint Arthroplasty: Financial Implications and Validation of an Adverse Event Assessment Form

BACKGROUND

In Ireland, funding of joint arthroplasty procedures has moved to a pay-by-results national tariff system. Typically, adverse clinical events are recorded via retrospective chart-abstraction methods by administrative staff. Missed or undocumented events not only affect the quality of patient care but also may unrealistically skew budgetary decisions that impact fiscal viability of the service. Accurate recording confers clinical benefits and financial transparency. The aim of this study was to compare a prospectively implemented adverse events form with the current national retrospective chart-abstraction method in terms of pay-by-results financial implications.

METHODS

An adverse events form adapted from a similar validated model was used to prospectively record complications in 51 patients undergoing total hip or knee arthroplasties. Results were compared with the same cohort using an existing data abstraction method. Both data sets were coded in accordance with current standards for case funding.

RESULTS

Overall, 114 events were recorded during the study through prospective charting of adverse events, compared with 15 events documented by customary method (a significant discrepancy). Wound drainage (15.8%) was the most common complication, followed by anemia (7.9%), lower respiratory tract infections (7.9%), and cardiac events (7%). A total of €61,956 ($67,778) in missed funding was calculated as a result.

CONCLUSION

This pilot study demonstrates the ability to improve capture of adverse events through use of a well-designed assessment form. Proper perioperative data handling is a critical aspect of financial subsidies, enabling optimal allocation of funds.

Preoperative Anemia Independently Predicts 30-Day Complications After Aseptic and Septic Revision Total Joint Arthroplasty

BACKGROUND

Preoperative anemia is a common, important risk factor for adverse events after joint arthroplasty surgery. It affects 21%-35% patients undergoing total joint arthroplasty. To date, few studies have investigated the effect of preoperative anemia, specifically in revision total joint arthroplasty surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was used to identify patients who underwent revision total joint arthroplasty from 2006 to 2014. We matched 6830 patients undergoing aseptic revision (3415 anemic vs 3415 not anemic) and 2650 patients undergoing septic revision (1325 anemic vs 1325 not anemic). In each cohort, patients were propensity score-matched 1:1 by the presence of preoperative anemia. The inpatient hospitalization data, postoperative complications, as well as demographics and comorbidities were compared between patients with or without anemia who underwent revision total joint arthroplasty.

RESULTS

After adjusting for comorbidities via multivariate regression, anemia was associated with an increased risk of overall complications (aseptic: odds ratio [OR], 1.45; 95% confidence interval [CI], 1.24-1.70; P < .001; septic: OR, 2.16; 95% CI, 1.83-2.56; P < .001), deep infection (aseptic: OR, 1.68; 95% CI, 1.19-2.38; P = .003; septic: OR, 1.44; 95% CI, 1.06-1.94; P = .018), mortality (aseptic: OR, 2.18; 95% CI, 1.09-4.36; P = .028; septic: OR, 3.16; 95% CI, 1.03-9.74; P = .045), and increased hospital length of stay (aseptic: adjusted coefficient, 1.02 days; 95% CI, 0.73-1.31; P < .001; septic: adjusted coefficient, 2.04 days; 95% CI, 1.53-2.55; P < .001).

CONCLUSION

Preoperative anemia is independently associated with postoperative complications, mortality, and increased length of stay in revision total joint arthroplasty. Further studies are needed to evaluate if preoperative treatment of anemia may modify this risk.

Type 2 diabetes and in-hospital complications after revision of total hip and knee arthroplasty

PURPOSE

To assess the effect of type 2 diabetes (T2DM) on hospital outcomes such as in hospital postoperative complications (IHPC), length of hospital stay (LOHS) and in-hospital mortality (IHM) after the revision of total hip arthroplasty (RHA) and total knee arthroplasty (RKA) and to identify factors associated with IHPC among T2DM patients undergoing these procedures.

METHODS

We performed a retrospective study using the Spanish National Hospital Discharge Database, 2005-2014. We included patients who were ≥40 years old that had undergone RHA and RKA. For each T2DM patient, we selected a year-, gender-, age- and Charlson Comorbidity Index-matched non-diabetic patient.

RESULTS

We identified 44,055 and 39,938 patients who underwent RHA (12.72% with T2DM) and RKA (15.01% with T2DM). We matched 4,700 and 5,394 couples with RHA and RKA, respectively. Any IHPC was more frequent among patients with T2DM than among non-T2DM patients (19% vs. 15.64% in the RHA cohort and 12.94% vs. 11.09% in the RKA cohort, respectively). For patients who underwent RHA, postoperative infection (4.51% vs. 2.94%, p<0.001), acute post-hemorrhagic anemia (9.53% vs. 7.70%, p<0.001), mean LOHS and IHM were significantly higher in patients with T2DM. Among RKA patients, the incidence of acute posthemorrhagic anemia (7.21% vs. 5.62%; p = 0.001) and urinary tract infection (1.13% vs. 0.72%; p = 0.029) was significantly higher in patients with diabetes. Older age, obesity, infection due to internal joint prosthesis, myocardial infarction, congestive heart failure, mild liver disease and renal disease and emergency room admission were significantly associated with a higher risk of IHPC in T2DM patients. IHPC decreased over time only in T2DM patients who underwent RHA (OR 0.94, 95%CI 0.89-0.98).

CONCLUSIONS

Patients with T2DM who underwent RHA and RKA procedures had more IHPC after controlling for the effects of possible confounders. LOHS and IHM were also higher among RHA patients with diabetes. Older age, comorbidity, obesity and emergency room admission were strong predictors of IHPC in diabetic patients.

Presentation and management of symptomatic central bone cement embolization

BACKGROUND CONTEXT

With more cement augmentation procedures done, the occurrence of serious complications is also expected to rise. Symptomatic central cement embolization is a rare but very serious complication. Moreover, the pathophysiology and treatment of intrathoracic cement embolism remain controversial.

PURPOSE

In this case series, we are trying to identify various presentations and suggest our emergent management scheme for symptomatic central cement embolization.

PATIENT SAMPLE

Retrospective case series of nine patients with symptomatic central cement embolism identified after vertebroplasty with 24 months of follow-up. Level IV.

OUTCOME MEASURES

The degree of dyspnea measured by the New York Heart Association (NYHA) score and/or death related to cement embolism induced cardio/respiratory failure at the final follow-up at 24 months.

METHODS

The nine patients, eight females, and one male had a mean age of 70.25 years (range 65-78 years) and were operated between January 2004 and December 2014. They had percutaneous vertebroplasty for osteoporotic non-traumatic and malignant vertebral collapse of dorsal and lumbar vertebrae. Post-vertebroplasty dyspnea and stitching chest pain were striking in the nine patients. After exclusion of cardiac ischemia and medical pulmonary causes for dyspnea, we identified radiopaque lesions on the chest X-ray. Further echocardiography and high-resolution chest CT were performed for optimal localization. Emergent heart surgery was performed in two patients: interventional therapy was conducted in one patient, while the remaining six patients were conservatively treated by anticoagulation. The management decision was taken in the setting of an interdisciplinary meeting depending on localization, fragmentation, and clinical status.

RESULTS

All patients of this series showed gradual improvement and an uneventful hospital stay. During our 24-month follow-up phase, eight patients showed no subsequent cardiological and/or respiratory symptoms (NYHA I). However, one mortality due to advanced malignancy occurred. Preoperative anemia was the only common intersecting preoperative parameter among these nine patients.

CONCLUSIONS

After cement augmentation, close clinical monitoring is mandatory. A chest CT is pivotal in determining the interdisciplinary management approach in view of the availability of necessary expertise, facilities and the location of the cement emboli whether accessible by cardiac or vascular surgical means. The clinical presentation and its timing may vary and the patient may be seen subsequently by other health care providers obligating a wide-spread awareness for this serious entity among health care providers for this age group as spine surgeons, family and emergency room doctors, and institutional or home-care nurses. Most symptomatic central cement emboli may be treated conservatively.

What is the Long-term Economic Societal Effect of Periprosthetic Infections After THA? A Markov Analysis

BACKGROUND

Current estimates for the direct costs of a single episode of care for periprosthetic joint infection (PJI) after THA are approximately USD 100,000. These estimates do not account for the costs of failed treatments and do not include indirect costs such as lost wages.

QUESTIONS/PURPOSES

The goal of this study was to estimate the long-term economic effect to society (direct and indirect costs) of a PJI after THA treated with contemporary standards of care in a hypothetical patient of working age (three scenarios, age 55, 60, and 65 years).

METHODS

We created a state-transition Markov model with health states defined by surgical treatment options including irrigation and débridement with modular exchange, single-stage revision, and two-stage revision. Reoperation rates attributable to septic and aseptic failure modes and indirect and direct costs were calculated estimates garnered via multiple systematic reviews of peer-reviewed orthopaedic and infectious disease journals and Medicare reimbursement data. We conducted an analysis over a hypothetical patient's lifetime from the societal perspective with costs discounted by 3% annually. We conducted sensitivity analysis to delineate the effects of uncertainty attributable to input variables.

RESULTS

The model found a base case cost of USD 390,806 per 65-year-old patient with an infected THA. One-way sensitivity analysis gives a range of USD 389,307 (65-year-old with a 3% reinfection rate) and USD 474,004 (55-year-old with a 12% reinfection rate). Indirect costs such as lost wages make up a considerable portion of the costs and increase considerably as age at the time of infection decreases.

CONCLUSIONS

The results of this study show that the overall treatment of a periprosthetic infection after a THA is markedly more expensive to society than previously estimated when accounting for the considerable failure rates of current treatment options and including indirect costs. These overall costs, combined with a large projected increase in THAs and a steady state of septic failures, should be taken into account when considering the total cost of THA. Further research is needed to adequately compare the clinical and economic effectiveness of alternative treatment pathways.

LEVEL OF EVIDENCE

Level II, economic and decision analysis.

Association between preoperative anaemia with length of hospital stay among patients undergoing primary total knee arthroplasty in Singapore: a single-centre retrospective study

OBJECTIVES

Studies in western healthcare settings suggest that preoperative anaemia is associated with poor outcomes after elective orthopaedic surgery. We investigated the prevalence of preoperative anaemia among patients with primary unilateral total knee arthroplasty (TKA) in Singapore and its association with length of hospital stay (LOS), perioperative blood transfusion and hospital readmission rates.

METHODS

Retrospective cohort study performed in a tertiary academic medical centre in Singapore, involving patients who underwent primary unilateral TKA between January 2013 and June 2014. Demographics, comorbidities, preoperative haemoglobin (Hb) level, LOS and 30-day readmission data were collected. Anaemia was classified according to WHO definition. Prolonged LOS was defined as more than 6 days, which corresponds to >75th centile LOS of the data.

RESULTS

We analysed 2394 patients. The prevalence of anaemia was 23.7%. 403 patients (16.8%) had mild anaemia and 164 patients (6.8%) had moderate to severe anaemia. Overall mean LOS was 5.4±4.8 days. Based on multivariate logistic regression, preoperative anaemia significantly increased LOS (mild anaemia, adjusted OR (aOR) 1.71, p<0.001; moderate/severe anaemia, aOR 2.29, p<0.001). Similar effects were seen when preoperative anaemia was defined by Hb level below 13 g/dL, regardless of gender. Transfusion proportionately increased prolonged LOS (1 unit: aOR 2.12, p=0.006; 2 or more units: aOR 6.71, p<0.001). Repeat operation during hospital stay, previous cerebrovascular accidents, general anaesthesia and age >70 years were associated with prolonged LOS. Our 30-day related readmission rate was 1.7% (42) cases.

CONCLUSION

Anaemia is common among patients undergoing elective TKA in Singapore and is independently associated with prolonged LOS and increased perioperative blood transfusion. We suggest measures to correct anaemia prior to surgery, including the use of non-gender-based Hb cut-off for establishing diagnosis.

Higher Modified Charlson Index Scores Are Associated With Increased Incidence of Complications, Transfusion Events, and Length of Stay Following Revision Hip Arthroplasty

BACKGROUND

Revision total hip arthroplasty (RHA) has been associated with greater morbidity and length of stay (LOS) compared to primary total hip arthroplasty. Despite this, few validated metrics exist for risk stratification in RHA cohorts. The Charlson Comorbidity Index (CCI) has been associated with complications in total hip arthroplasty, but its utility in revision surgery remains unexplored. The purpose of this study was to examine the relationship between preoperative CCI and a variety of outcome metrics following RHA.

METHODS

The National Surgical Quality Improvement Program database was used to identify all patients undergoing aseptic RHA between 2006 and 2013. A variety of demographics and perioperative variables were collected. Modified CCI scores were computed for each patient based on a validated formula incorporating comorbidities found in the National Surgical Quality Improvement Program database. Outcome variables of interest included mortality, major postoperative complications, minor adverse events, incidence of transfusion, and prolonged LOS. Perioperative factors were tested for association with these outcomes using bivariate analysis and significant variables were then incorporated into a logistic regression model to explore the relationship between preoperative CCI scores and postoperative events.

RESULTS

In a multivariable regression model controlling for the significant perioperative variables, operative time, and American Society of Anesthesiologists classification, higher CCI scores were significantly associated with mortality (odds ratio [OR] 1.89, 95% confidence interval [CI] 1.64-2.18, P < .001), major complications (OR 1.12, 95% CI 1.05-1.20, P = .001), minor complications (OR 1.53, 95% CI 1.39-1.69, P < .001), transfusions (OR 1.14, 95% CI 1.09-1.20, P < .001), and prolonged LOS (OR 1.32, 95% CI 1.26-1.39, P < .001).

CONCLUSION

Higher preoperative CCI scores were independent risk factors for numerous complications. This highlights the potential utility of the CCI in risk stratification for RHA populations.

Length of stay after shoulder arthroplasty-the effect of an orthopedic specialty hospital

BACKGROUND

One potential avenue for the realization of health care savings is reduction in hospital length of stay (LOS). Initiatives to reduce LOS may also reduce infection and improve patient satisfaction. We compare LOS after shoulder arthroplasty at an orthopedic specialty hospital (OSH) and a tertiary referral center (TRC).

METHODS

A single institutional database was used to retrospectively identify all primary shoulder arthroplasties performed between January 1, 2013, and July 1, 2015, at the OSH and TRC. Manually matched cohorts from the OSH and TRC were compared for LOS and readmission rate.

RESULTS

There were 136 primary shoulder arthroplasties performed at the OSH matched with 136 at the TRC during the same study period. OSH and TRC patients were similar in age (P = .949), body mass index (P = .967), Charlson Comorbidity Index (P = 1.000), gender (both 52.21% male), procedure (69.12% total shoulder arthroplasty, 7.35% hemiarthroplasty, and 23.53% reverse shoulder arthroplasty), insurance status (P = .714), and discharge destination (P = .287). Despite equivalent patient characteristics, average LOS at the OSH was 1.31 ± 0.48 days compared with 1.85 ± 0.57 days at the TRC (t = 8.41, P < .0001). Of the 136 OSH patients, 3 (2.2%) required transfer to a TRC. Readmission rates for the OSH patients (2/136, 1.5%) and TRC patients (1/136, 0.7%) were similar (z = 0.585, P = .559).

CONCLUSION

LOS at the OSH was significantly shorter than at the TRC for a strictly matched cohort of patients. This may be a result of fast-track rehabilitation and strict disposition protocols at the OSH. With rising shoulder arthroplasty demand, utilization of an OSH may be a safe avenue to delivery of more efficient and effective orthopedic care.

Major Complications and Transfusion Rates After Hemiarthroplasty and Total Hip Arthroplasty for Femoral Neck Fractures

BACKGROUND

Postoperative complications and perioperative transfusions are common after hemiarthroplasty or total hip arthroplasty (THA) and can lead to increased morbidity and mortality.

METHODS

The National Surgical Quality Improvement Program Database was queried to compare 30-day major complications and perioperative transfusions after femoral neck fractures.

RESULTS

A total of 4058 patients were included in the study: 3192 were treated with hemiarthroplasty and 866 with THA. Multivariable logistic regression analysis revealed that having a THA was not an independent risk factor for major complications (odds ratio = 0.8, P = .18) but was an independent risk factor for requiring transfusions (odds ratio = 1.68, P < .001).

CONCLUSION

The risk of major complications is influenced by patient factors rather than the choice of procedure. However, THA was a risk factor for transfusions after controlling for all other variables.

Risk factors for revision of total knee arthroplasty: a scoping review

Background

In spite of the increasing incidence of total knee arthroplasties (TKA), evidence is limited regarding risk factors for revision. The objective of this scoping review was to identify and assess demographic, surgical and health services factors that may increase the risk for revision surgery following TKA.

Methods

A scoping review was undertaken following an electronic search in MEDLINE (1990 to December 2013), CINAHL (to December 2013), EMBASE (1990 to December 2013) and Web of Science (1990 to December 2013).

Results

Of the 4460 articles screened, 42 were included of which 26 articles were based on registry data. Increased risk of revision was associated with demographic factors (younger age, African American), surgical factors related to the primary TKA (uncemented components, implant malalignment, increased surgery duration), and health services (low volume hospitals).

Conclusions

Identifying emerging trends in characteristics of those requiring revision following TKA can help identify those at risk and allocate appropriate resources. Further primary clinical articles on risk factors for revision of TKA are necessary to ensure maximal function and lifespan following TKAs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-016-1025-8) contains supplementary material, which is available to authorized users.