Timing of acute myocardial infarction in patients undergoing total hip or knee replacement: a nationwide cohort study

Super-Obesity is Associated with an Increased Risk of Complications Following Primary Total Knee Arthroplasty

BACKGROUND

Obesity, defined as a body mass index (BMI) ≥ 30, is an ever-growing epidemic, with > 35% of adults in the United States currently classified as obese. Super-obese individuals, defined as those who have a BMI ≥ 50, are the fastest-growing portion of this group. This study sought to quantify the infection risk as well as the incidence of surgical, medical, and thromboembolic complications among super-obese patients undergoing total knee arthroplasty (TKA).

METHODS

An all-payer claims database was used to identify patients who underwent elective, primary TKA between 2016 and 2021. Patients who had a BMI ≥ 50 were compared to those who had a normal BMI of 18 to 25. Demographics and the incidence of 90-day postoperative complications were compared between the two groups. Univariate analysis and multivariable regression were used to assess differences between groups.

RESULTS

In total, 3,376 super-obese TKA patients were identified and compared to 17,659 patients who had a normal BMI. Multivariable analysis indicated that the super-obese cohort was at an increased postoperative risk of periprosthetic joint infection (PJI) (adjusted odds ratio [aOR] 3.7, 95% confidence interval [CI]: 2.1 to 6.4, P < 0.001), pulmonary embolism (aOR 2.2, 95%-CI: 1.0 to 5.0, P = 0.047), acute respiratory failure (aOR 4.1, 95%-CI: 2.7 to 6.1, P < 0.001), myocardial infarction (aOR 2.5, 95%-CI: 1.1 to 5.8, P = 0.026), wound dehiscence (aOR 2.3, 95%-CI: 1.4 to 3.8, P = 0.001), and acute renal failure (aOR 3.2, 95%-CI: 2.4 to 4.2, P < 0.001) relative to patients who have normal BMI.

CONCLUSION

Super-obese TKA patients are at an elevated risk of postoperative infectious, surgical, medical, and thromboembolic complications. As such, risk stratification, as well as appropriate medical management and optimization, is of utmost importance for this high-risk group.

Simultaneous bilateral total hip arthroplasty-a survey of Irish orthopaedic surgeons' practice

BACKGROUND

Bilateral total hip arthroplasty may be performed simultaneously (SIMTHA) or in two staged operations.

AIM

To assess attitudes towards and utilization of SIMTHA in Irish orthopaedic practice, and to assess patient and surgeon factors which are associated with the management of bilateral hip arthritis.

METHODS

A 16-question electronic survey (Google Forms) was distributed via email to consultant Irish orthopaedic surgeons who perform total hip arthroplasty, followed by a reminder 1 month later. A p value < 0.05 was considered significant.

RESULTS

There were 53 responses from arthroplasty surgeons, with 28% reporting they never perform SIMTHA, 26% have performed ≤ 5 SIMTHA, and 46% do ≥ 1 SIMTHA per year. Amongst the 15 surgeons who do not do SIMTHA, 60% reported a preference for staged arthroplasty, 20% felt it was not feasible in their institution, and a third reported a lack of experience with SIMTHA. There was a significant association between not performing SIMTHA and years of consultant experience (p = 0.002). There were no institutional guidelines on eligibility criteria for SIMTHA. The most common time interval for staged bilateral arthroplasty was 6-12 weeks (60%). Overall, 56% of surgeons felt SIMTHA is underutilised in the Irish healthcare system; this was associated with greater SIMTHA volume (p = 0.023).

CONCLUSION

Half of the Irish arthroplasty surgeons report SIMTHA is a regular aspect of their practice. Performing SIMTHA is associated with greater arthroplasty volume, more recent consultant appointments, and a perception that the operation is underutilised.

Risk factors for in-patient myocardial infarction following total hip arthroplasty

Purpose

The aim of this study was to identify potential risk factors for myocardial infarction immediately following total hip arthroplasty.

Methods

The 2016-2019 Nationwide Inpatient Sample database was used to identify patients who underwent primary total hip arthroplasty (THA) and suffered a myocardial infarction (MI). Patient data including demographics, admission, and comorbidities were recorded. Univariate analysis and subsequent multivariate logistic regression were performed to determine which circumstances affected the odds of MI.

Results

A total of 367,890 patients were identified for THA with 142 of those also having a myocardial infarction. Those who experienced an MI had increased length of stay, total charges, and generally negative dispositions compared to their non-MI counterparts (p < 0.001). Through regression analysis, factors that increased the odds of MI included older age [odds ratio (OR) 1.59, 95 % confidence interval (CI) 1.49-1.70], a female sex (OR 1.46, 95 % CI 1.37-1.55), previous coronary artery bypass graft (OR 1.20, 95 % CI 1.01-1.43), obesity (OR 1.12, 95 % CI 1.04-1.21), colostomy (OR 2.07, 95 % CI 1.21-3.56), and Parkinson's disease (OR 1.48, 95 % CI 1.13-1.95). Factors that decreased that risk included elective admission (OR 0.21, 95 % CI 0.19-0.22) and a tobacco related disorder (OR 0.69, 95 % CI 0.63-0.76).

Conclusions

Patient risk for myocardial infarction following total hip arthroplasty varies in part based on their background and comorbidities. These findings can be used to better recognize those who should receive further precautions and tailor proper treatment strategies for THA.

Cellular and Molecular Mechanisms of Mast Cells in Atherosclerotic Plaque Progression and Destabilization

Mast cells (MCs) are commonly recognized for their crucial involvement in the pathogenesis of allergic diseases, but over time, it has come to light that they also play a role in the pathophysiology of non-allergic disorders including atherosclerosis. The involvement of MCs in the pathology of atherosclerosis is supported by their accumulation in atherosclerotic plaques upon their progression and the association of intraplaque MC numbers with acute cardiovascular events. MCs that accumulate within the atherosclerotic plaque release a cocktail of mediators through which they contribute to neovascularization, plaque progression, instability, erosion, rupture, and thrombosis. At a molecular level, MC-released proteases, especially cathepsin G, degrade low-density lipoproteins (LDL) and mediate LDL fusion and binding of LDL to proteoglycans (PGs). Through a complicated network of chemokines including CXCL1, MCs promote the recruitment of among others CXCR2+ neutrophils, therefore, aggravating the inflammation of the plaque environment. Additionally, MCs produce extracellular traps which worsen inflammation and contribute to atherothrombosis. Altogether, evidence suggests that MCs actively, via several underlying mechanisms, contribute to atherosclerotic plaque destabilization and acute cardiovascular syndromes, thus, making the study of interventions to modulate MC activation an interesting target for cardiovascular medicine.

Prevention of perioperative stroke in patients undergoing non-cardiac surgery

About 300 million adults undergo non-cardiac surgery annually. Although, in this setting, the incidence of perioperative stroke is low, the absolute number of patients experiencing a stroke is substantial. Furthermore, most patients with this complication will die or end up with severe disability. Covert brain infarctions are more frequent than overt strokes and are associated with postoperative delirium, cognitive decline, and cerebrovascular events at 1 year after surgery. Evidence shows that traditional stroke risk factors including older age, hypertension, and atrial fibrillation are also associated with perioperative stroke; previous stroke is the strongest risk factor for perioperative stroke. Increasing evidence also suggests the pathogenic role of perioperative events, such as hypotension, new atrial fibrillation, paradoxical embolism, and bleeding. Clinicians involved in perioperative care should be aware of this evidence on prevention strategies to improve patient outcomes after non-cardiac surgery.

Timing of adverse events in patients undergoing acute and elective hip arthroplasty surgery: a multicentre cohort study using the Global Trigger Tool

OBJECTIVE

To explore timing in relation to all types of adverse events (AEs), severity and preventability for patients undergoing acute and elective hip arthroplasty.

DESIGN

A multicentre cohort study using retrospective record review with Global Trigger Tool methodology in combination with data from several registers.

SETTING

24 hospitals in 4 major regions of Sweden.

PARTICIPANTS

Patients ≥18 years, undergoing acute or elective total or hemiarthroplasty of the hip, were eligible for inclusion. Reviews of weighted samples of 1998 randomly selected patient records were carried out using Global Trigger Tool methodology. The patients were followed for readmissions up to 90 days postoperatively throughout the whole country.

RESULTS

The cohort consisted of 667 acute and 1331 elective patients. Most AEs occurred perioperatively and postoperatively (n=2093, 99.1%) and after discharge (n=1142, 54.1%). The median time from the day of surgery to the occurrence of AE was 8 days. The median days for different AE types ranged from 0 to 24.5 for acute and 0 to 71 for elective patients and peaked during different time periods. 40.2% of the AEs, both major and minor, occurred within postoperative days 0-5 and 86.9% of the AEs occurred within 30 days. Most of the AEs were deemed to be of major severity (n=1370, 65.5%) or preventable (n=1591, 76%).

CONCLUSIONS

A wide variability was found regarding the timing of different AEs with the majority occurring within 30 days. The timing and preventability varied regarding the severity. Most of the AEs were deemed to be preventable and/or of major severity. To increase patient safety for patients undergoing hip arthroplasty surgery, a better understanding of the multifaceted nature of the timing of AEs in relation to the occurrence of differing AEs is needed.

The Differential Systemic Biological Effects between Computer Navigation and Conventional Total Knee Arthroplasty (TKA) Surgeries: A Prospective Study

Distal femur reaming-free total knee arthroplasty (TKA) was reported to possess lower risk of acute myocardial infarction (AMI) or venous thromboembolism (VTE) than conventional TKA in a retrospective population-based study. We tried to offer prospective biological evidence by comparing the levels of AMI and VTE serum surrogate markers among the patients undertaking navigation and conventional TKAs to support these observations. Thirty-four participants undertaking navigation TKA and 34 patients receiving conventional TKA were recruited between February 2013 and December 2015. Blood samples were drawn from all participants before TKA, and 24 and 72 h after TKA, to assess the concentration of soluble P-selectin, matrix metalloproteinase-9 (MMP-9), C-reactive protein (CRP), and interleukin-8 (IL-8) between the participants undergoing navigation and conventional TKAs. We showed that significantly lower serum levels of soluble P-selectin 24 h after, as well as CRP 24 and 72 h after TKA could be observed in the navigation cohort. The more prominent surge of serum soluble P-selectin and CRP were perceived 24 and 72 h after TKA among the participants undergoing conventional TKA. Based upon our prospective biological evidence, the merits of navigation TKA are strengthened by lower levels of AMI and VTE serum surrogate markers.

The Risk of Bleeding and Adverse Events with Clopidogrel in Elective Hip and Knee Arthroplasty Patients

Orthopedic surgeons often face a clinical dilemma on how to manage antiplatelet therapies during the time of surgery. This retrospective study is aimed to investigate the bleeding risk and adverse events in patients who hold or keep clopidogrel during elective major joints arthroplasty. Two hundred and ninety-six patients that were treated with clopidogrel while undergoing total hip or knee joint replacement between January 2009 and December 2018 were studied. Group 1 included 56 patients (18.9%) who kept using clopidogrel preoperatively. Group 2 included 240 patients who hold clopidogrel use ≥5 days preoperatively. Blood transfusion rates, estimated blood loss, complication rates, and adverse cardiocerebral events were collected and analyzed. The mean total blood loss was more in the group 1 patients as compared with that in the group 2 patients (1212.3 mL (685.8 to 2811.8) vs. 1068.9 mL (495.6 to 3294.3), p = 0.03). However, there was no significant difference between the two groups of patients regarding transfusion rates, bleeding-related complications, and infection rates. There was a trend toward a higher incidence of adverse cardiocerebral events in patients withholding clopidogrel for more than 5 days before surgery. The results of this study suggest that clopidogrel continuation could be safe and advisable for patients at thrombotic risk undergoing primary major joint replacement. Acute antiplatelet withdrawal for an extended period of time might be associated with an increased risk of postoperative thromboembolic events. More studies are required in the future to further prove this suggestion.

Should we use similar perioperative protocols in patients undergoing unilateral and bilateral one-stage total knee arthroplasty?

BACKGROUND

Bilateral one-stage total knee arthroplasty (BTKA) is now in greater use as an alternative option for patients with bilateral end-stage knee arthropathy. However, postoperative pain and disablement during convalescence from BTKA, and procedure-related complications have been concerning issues for patients and surgeons. Although some studies reported that BTKA in selected patients is as safe as the staged procedure, well-defined guidelines for patient screening, and perioperative care and monitoring to avoid procedure-related complications are still controversial.

AIM

To compare the perioperative outcomes including perioperative blood loss (PBL), cardiac biomarkers, pain intensity, functional recovery, and complications between unilateral total knee arthroplasty (UTKA) and BTKA performed with a similar perioperative protocol.

METHODS

We conducted a retrospective study on consecutive patients undergoing UTKA and BTKA that had been performed by a single surgeon with identical perioperative protocols. The exclusion criteria of this study included patients with an American Society of Anesthesiologists score > 3, and known cardiopulmonary comorbidity or high-sensitivity Troponin-T (hs-TnT) > 14 ng/L. Outcome measures included visual analogue scale (VAS) score of postoperative pain, morphine consumption, range of knee motion, straight leg raise (SLR), length of stay (LOS), and serum hemoglobin (Hb) and hs-TnT monitored during hospitalization.

RESULTS

Of 210 UTKA and 137 BTKA patients, those in the BTKA group were younger and more predominately female. The PBL of the UTKA vs BTKA group was 646.45 ± 272.26 mL vs 1012.40 ± 391.95 mL (P < 0.01), and blood transfusion rates were 10.48% and 40.88% (P < 0.01), respectively. Preoperative Hb and body mass index were predictive factors for blood transfusion in BTKA, whereas preoperative Hb was only a determinant in UTKA patients. The BTKA group had significantly higher VAS scores than the UTKA group at 48, 72, and 96 h after surgery, and also had a significantly lower degree of SLR at 72 h. The BTKA group also had a significantly longer LOS than the UTKA group. Of the patients who had undergone the procedure, 5.71% of the UTKA patients and 12.41% of the BTKA patients (P = 0.04) had hs-TnT > 14 ng/L during the first 72 h postoperatively. However, there was no difference in other outcome measures and complications.

CONCLUSION

Following similar perioperative management, the blood transfusion rate in BTKA is 4-fold that required in UTKA. Also, BTKA is associated with higher pain intensity at 48 h postoperatively and prolonged LOS when compared to the UTKA. Hence, BTKA patients may require more extensive perioperative management for blood loss and pain, even if having no higher risk of complications than UTKA.

Patients With a History of a Cardiac Implantable Electronic Device Have a Higher Likelihood of 90-Day Cardiac Events After Total Joint Arthroplasty: A Matched Cohort Study

INTRODUCTION

We sought to identify the incidence of new 90-day cardiac events, 90-day mortality, 90-day unplanned readmissions, and 30-day emergency department (ED) visits after total joint arthroplasty (TJA) in patients with a history of a cardiac implantable electronic device (CIED) and compare these outcomes in TJA patients without a CIED.

METHODS

Kaiser Permanente's Cardiac Device and Total Joint Replacement Registries were used to identify elective primary TJA performed for osteoarthritis. TJA with a CIED was matched with TJA without a CIED (n = 365 pairs) on patient characteristics, demographics, and procedure type. A McNemar test was used to evaluate categorical outcomes.

RESULTS

Of the TJA with a CIED, there were 24 cardiac events (6.6%), 1 mortality (0.3%), 30 readmissions (8.2%), and 39 ED visits (10.7%). TJA patients with a CIED had a higher likelihood of cardiac events (odds ratio [OR] = 3.14, 95% confidence interval [CI] = 1.28 to 8.08). No difference was observed in mortality (OR = 0.50, 95% CI = 0.02 to 6.98), readmissions (OR = 1.26, 95% CI = 0.71 to 2.25), or ED visits (OR = 1.15, 95% CI = 0.71 to 1.88).

CONCLUSION

In our matched cohort study, TJA patients with a history of a CIED had a higher likelihood of incident 90-day cardiac events when compared with patients without a CIED without a difference observed for 90-day mortality, unplanned readmission, and 30-day ED visit.

LEVEL OF EVIDENCE

Level III.

Association Between Myocardial Injury and Cardiovascular Outcomes of Orthopaedic Surgery: A Vascular Events in Noncardiac Surgery Patients Cohort Evaluation (VISION) Substudy

BACKGROUND

Myocardial injury after noncardiac surgery (MINS) is common and of prognostic importance. Little is known about MINS in orthopaedic surgery. The diagnostic criterion for MINS was a level of ≥0.03 ng/mL on a non-high-sensitivity troponin T (TnT) assay due to myocardial ischemia.

METHODS

We undertook an international, prospective study of 15,103 patients ≥45 years of age who had inpatient noncardiac surgery; 3,092 underwent orthopaedic surgery. Non-high-sensitivity TnT assays were performed on postoperative days 0, 1, 2, and 3. Among orthopaedic patients, we determined (1) the prognostic relevance of the MINS diagnostic criteria, (2) the 30-day mortality rate for those with and without MINS, and (3) the probable proportion of MINS cases that would go undetected without troponin monitoring because of a lack of an ischemic symptom.

RESULTS

Three hundred and sixty-seven orthopaedic patients (11.9%) had MINS. MINS was associated independently with 30-day mortality including among those who had had orthopaedic surgery. Orthopaedic patients without and with MINS had a 30-day mortality rate of 1.0% and 9.8%, respectively (odds ratio [OR], 11.28; 95% confidence interval [CI], 6.72 to 18.92). The 30-day mortality rate was increased for patients with MINS who had an ischemic feature (i.e., symptoms, or evidence of ischemia on electrocardiography or imaging) (OR, 18.25; 95% CI, 10.06 to 33.10) and for those who did not have an ischemic feature (OR, 7.35; 95% CI, 3.37 to 16.01). The proportion of orthopaedic patients with MINS who were asymptomatic and in whom the myocardial injury would have probably gone undetected without TnT monitoring was 81.3% (95% CI, 76.3% to 85.4%).

CONCLUSIONS

One in 8 orthopaedic patients in our study had MINS, and MINS was associated with a higher mortality rate regardless of symptoms. Troponin levels should be measured after surgery in at-risk patients because most MINS cases (>80%) are asymptomatic and would go undetected without routine measurements.

LEVEL OF EVIDENCE

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

Retrospective Cohort Study Comparing Complications, Readmission, Transfusion, and Length of Stay of Patients Undergoing Simultaneous and Staged Bilateral Total Hip Arthroplasty

Objectives

To determine whether the rates of postoperative complications, rate of readmission, cumulative transfusion volume, and length of stay (LOS) differ between simultaneous total hip arthroplasty (THA) and staged bilateral THA and to assess whether the length of the interval between staged procedures influences surgery outcome.

Methods

This was a retrospective cohort study comparing the rate of postoperative complications, readmission, cumulative transfusion volume, and LOS between simultaneous THA and staged bilateral THA in our hospital's registration database. The inclusion criteria is listed as follows: patients who underwent bilateral primary THA between January 2011 and January 2015 with minimum 3‐month follow‐up; simultaneous bilateral THA; staged bilateral THA; postoperative complications, readmission, cumulative transfusion volume, length of stay of the patients and the influence of the interval between stages of bilateral THA on the outcome above; and retrospective cohort study. Finally, a total of 1145 patients, including simultaneous bilateral THA in 863 patients (1726 hips) and staged bilateral THA in 282 patients (564 hips), were eligible for the present study. The patients were divided into three groups according to the interval time (≤30 days, 30–90 days, >90 days) between the two stages of bilateral THA and we compared postoperative complications, readmission rates, cumulative transfusion volume, and LOS for the three groups. All patients’ medical records and outpatient notes were reviewed to extract preoperative data, perioperative complications, readmission, cumulative transfusion, and LOS. Preoperative information included patients’ age, sex, diagnosis, body mass index, and American Society of Anesthesiologists (ASA) classification. Perioperative complications were sorted into two groups: (i) medical complications included cardiovascular, pulmonary, neurological, digestive, and urologic system complications, along with other miscellaneous issues; and (ii) surgical complications included dislocation, superficial wound infection, hematoma, deep periprosthetic joint infection, and nerve palsy. Patients who failed to come back to visit our hospital in the postoperative 3 months were followed up by telephone, at which point we inquired about any postoperative complications and readmission.

Results

Simultaneous THA was performed more often in younger men, and patients in the simultaneous group had fewer major medical complications (excluding venous thromboembolism), fewer surgical complications, and shorter hospital stays; however, patients in the simultaneous group were likelier to have a higher transfusion rate than patients in the staged group. Among patients in the staged group, there were no differences for differing time intervals, except that patients with a between‐stage interval of ≤30 days required more blood transfusions.

Conclusion

With careful patient assessment and selection, simultaneous bilateral THA is a safe procedure, and has lower rates of surgical and major medical complications than staged bilateral THA.

The impact of BMI and smoking on risk of revision following knee and hip replacement surgery: evidence from routinely collected data

OBJECTIVE

The aim of this study was to assess the association of body mass index (BMI) and smoking with risk of revision following total knee replacement (TKR) and total hip replacement (THR).

DESIGN

Primary care data, from the Clinical Practice Research Datalink (CPRD), was linked to inpatient hospital records, from Hospital Episode Statistics Admitted Patient Care (HES APC), and covered 1997 to 2014. Parametric survival models, with BMI and smoking status included as explanatory variables, were estimated for 10-year risk of revision and mortality, and were extrapolated to estimate lifetime risk of revision.

FINDINGS

TKR and THR cohorts included 10,260 and 10,961 individuals, respectively. For a change in BMI from 25 to 35, the 10-year risk of revision is expected change from 4.6% (3.3-6.4%) to 3.7% (2.6-5.1%) for TKR and 3.7% (2.8-5.1%) to 4.0% (2.8-5.7%) for THR for an otherwise average patient profile. Meanwhile, changing from a non-smoker to a current smoker is expected to change the risk of revision from 4.1% (3.1-5.5%) to 2.8% (1.7-4.7%) for TKR and from 3.8% (2.8-5.3%) to 2.9% (1.9-4.7%) for THR for an otherwise average patient profile. Estimates of lifetime risk were also similar for different values of BMI or smoking status.

CONCLUSIONS

Obesity and smoking do not appear to have a meaningful impact on the risk of revision following TKR and THR.

Previous History of Breast Cancer Increases Rates of Pulmonary Embolism and Costs after Total Knee Arthroplasty: An Evaluation of 185,114 Matched Patients

Risk factors for adverse events after total knee arthroplasty (TKA) relating to malignancy have not been well studied. Thus, the purpose of this study was to conduct a retrospective case-control outcome and cost analysis after TKA in this population. Patients with a history of breast cancer (BrCa) were identified based on the International Classification of Disease 9th revision codes. An age- and sex-matched cohort was also identified of patients without a history of BrCa. Complications, length of stay, comorbidity burden, and reimbursements were tracked at 90 days. Each cohort comprised 92,557 patients. Length of stay was similar between cohorts (p = 0.627). Comorbidity status and incidence of pulmonary embolism (PE), lower extremity ultrasound, and chest computed tomography (CT) use were higher in patients with a history of BrCa (p < 0.05 for all). Control patients had a lower incidence of acute myocardial infarction (0.14 vs. 0.21%; p < 0.001). Surgical complications were similar. The 90-day reimbursements were greater in patients with a history of BrCa (US$13,990 vs. US$13,033 for controls; p = 0.021). Surgeons should be aware of the increased risk of PE after TKA in patients with a history of BrCa as well as increased 90-day costs, which warrant great attention.

Myocardial infarction following fast-track total hip and knee arthroplasty-incidence, time course, and risk factors: a prospective cohort study of 24,862 procedures

Background and purpose - Acute myocardial infarction (MI) is a leading cause of mortality following total hip and knee arthroplasty (THA/TKA). The reported 30-day incidence of MI varies from 0.3% to 0.9%. However, most data derive from administration and insurance databases or large RCTs with potential confounding factors. We studied the incidence of and potential modifiable risk factors for postoperative MI in a large, multicenter optimized "fast-track" THA/TKA setting. Patients and methods - A prospective cohort study was conducted on consecutive unselected elective primary unilateral THA and TKA, using prospective information on comorbidities and complete 90-day follow-up from the Danish National Patient Registry. Evaluation of discharge summaries and medical records was undertaken in cases of suspected MI. Logistic regression analyses were carried out for identification of preoperative risk factors. Results - Of 24,862 procedures with a median length of stay 2 (IQR 2-3) days, 30- and 90-day incidence of MI was 31 (0.12%) and 48 (0.19%). Preoperative risk factors for MI ≤30 days were age >85 years (OR 7.4, 95% CI 2.3-24), insulin-dependent diabetes mellitus (IDDM) (3.6, CI 1.1-12), cardiovascular disease (2.4, CI 1.1-5.0) and hypercholesterolemia (2.3, CI 1.1-5.1). Of 31 patients with MI ≤30 days 9 were treated with vasopressors for intraoperative hypotension and 27 had postoperative anemia. Interpretation - Fast-track THA and TKA had a low 30-day MI incidence. Focus on patients with age >85, IDDM, cardiovascular disease, and hypercholesterolemia may further reduce the 30-day incidence of MI. The role of postoperative anemia and intraoperative hypotension are other areas for further improvement.

The impact of rheumatoid arthritis on the risk of adverse events following joint replacement: a real-world cohort study

Purpose

To assess whether rheumatoid arthritis (RA) is associated with a greater risk of adverse events following total knee replacement (TKR) and total hip replacement (THR) than osteoarthritis (OA).

Patients and methods

Individuals with a diagnosis of RA or OA were identified using primary care records. TKR and THR following diagnosis were identified using linked hospital records. Myocardial infarction (MI), prosthetic joint infection (PJI), venous thromboembolism (VTE), and death were identified within 90 days following surgery, and revision procedures over 10 years following surgery. The impact of RA compared to OA on the risk for these adverse events was assessed using Cox proportional hazard models. Univariable models, with diagnosis as the only explanatory variable, and multivariable models, with age, gender, and year of surgery first added and then a measure of other comorbidities also included, were estimated.

Results

In all 20,763 individuals, with 10,260 TKR and 10,961 THR, were included in the analysis. Compared to those with OA, individuals with a diagnosis of RA had a greater incidence of MI over 90 days following TKR (OA: 0.28%, RA: 0.75%) and revision over 10 years following THR (OA: 5.55%, RA: 8.68%). Both of these differences were statistically significant with, for example, hazard ratios of 3.54 (1.44 to 8.73) for MI and 1.61 (1.06 to 2.46) for revision after controlling for age, gender, year of surgery, and other comorbidities.

Conclusion

These findings suggest that, compared to individuals with OA, those with RA have an increased short-term risk of MI following TKR. While risk of MI remains below 1%, this does underline the importance of the management of cardiovascular risk factors for those with RA. RA was also associated with an increased long-term risk of revision following THR, which strengthens the argument for investing in therapies which may prevent the need for joint replacement.

Effects of computer-assisted navigation versus conventional total knee arthroplasty on the levels of inflammation markers: A prospective study

Total knee arthroplasty (TKA) is a well-established modality for the treatment of advanced knee osteoarthritis (OA). However, the detrimental effects of intramedullary reaming used in conventional TKA for distal femur cutting are of concern. Avoiding intramedullary reaming with the use of computer-assisted navigation TKA can not only provide superior prosthetic alignment, but also mitigate perioperative blood loss and the dissipation of marrow emboli. We quantified local and systemic concentrations of inflammation markers for both techniques. Forty-four participants undergoing computer-assisted navigation and 53 receiving conventional TKA for advanced knee OA were recruited between 2013/02/08 and 2015/12/09. Blood samples were collected from all participants at baseline then again at 24 and 72 hours postoperatively and analyzed by ELISA for interleukin 6 (IL-6), IL-10, tumor necrosis factor alpha (TNF-α) and transforming growth factor beta 1 (TGF-β1); these markers were also measured in Hemovac drain fluid collected at 24 and 72 hours. Serum levels of IL-6, IL-10, TNF-α and TGF-β1(unit for all markers: pg/mL) were increased from baseline by smaller increments in the navigation TKA cohort compared with the conventional TKA group at 24 hours (17.06 vs 29.39, p = 0.02; 0.51 vs 0.83, p = 0.16; -0.04 vs 0.36, p < 0.01 and -48.18 vs 63.24, p< 0.01, respectively) and at 72 hours (12.27 vs 16.87, p = 0.01; -0.40 vs 0.48, p < 0.01; 0.58 vs 0.98, p = 0.07 and -55.16 vs 63.71, p < 0.01, respectively). IL-10 levels in drainage fluids collected 24 hours after TKA were also significantly lower in the navigation group versus the conventional TKA group (8.55 vs 12.32, p < 0.01). According to our evidence, the merits of computer-assisted navigation TKA are augmented by low levels of inflammation markers.

Total hip arthroplasty and cardiovascular complications: a review

Most adverse events following total hip arthroplasty (THA) are uncommon and preventable or treated easily as expected. Adverse effects related to any major surgical procedure, including anesthesia, performing with other medical problems, drugs, and allergic reactions, might also occur. Potential cardiovascular complications are known to occur during or following THA and will be reviewed here. Complications can be categorized as myocardial infarction, cardiac arrest, thromboembolism, and so on. Special considerations in cardiovascular procedures are also reviewed in this paper.

Osteoarthritis, cerebrovascular dysfunction and the common denominator of inflammation: a narrative review

OBJECTIVE

Population-based cohort studies suggest an association between osteoarthritis (OA) and cerebrovascular disease, yet the mechanisms underlying vascular comorbidities in OA remain unclear. The purpose of this narrative review is to discuss the literature examining inflammation in OA with a focus on physiological mechanisms, and whether overlapping mechanisms exist in cerebrovascular dysfunction.

METHOD

A literature search was conducted in PubMed using combinations of search terms: osteoarthritis, cerebrovascular (disease/dysfunction/risk), cardiovascular (disease/dysfunction/risk), aging/ageing, inflammation, inflammatory mediators, cytokine, c-reactive protein, interleukin, advanced glycation end-products, metabolic syndrome, reactive oxidative species, cognitive impairment, (vascular-related) dementia, small cerebral vessel disease, endothelial function, blood-brain barrier, gender/sex, hypertension, peripheral vascular health, and physical activity. Reference lists of identified articles were also researched manually.

RESULTS

Overlapping inflammatory factors that may contribute to onset and progression of both OA and cerebrovascular dysfunction are presented. We describe oxidative mechanisms involving pro-inflammatory cytokines and oxidative species, advanced glycation end-products, sex hormones, microvascular dysfunction and osteoprotegerin, and their specific roles in potentially contributing to OA and cerebrovascular dysfunction.

CONCLUSION

Synthesis of the current literature suggests future investigations may benefit from directly testing cerebrovascular hemodynamics and cognitive function in individuals with or at risk of OA to elucidate common physiological mechanisms.

Postoperative Myocardial Injury and Inflammation Is Not Blunted by a Trial of Atorvastatin in Orthopedic Surgery Patients

BACKGROUND

Orthopedic patients are at risk for adverse postoperative cardiovascular outcomes.

QUESTIONS/PURPOSES

This pilot randomized controlled trial (RCT) of atorvastatin vs. placebo in orthopedic surgery patients was performed in order to assess: (1) the prevalence of perioperative myocardial injury; (2) the effect of atorvastatin on perioperative inflammation; and (3) the feasibility of performing a large RCT of statin therapy in orthopedic patients.

METHODS

Hip fracture (hip Fx) and total hip and knee replacement (THR and TKR) patients were randomized 1:1 to atorvastatin 40 mg daily vs. placebo, starting preoperatively and continuing until postoperative day (POD) 45. High-sensitivity cardiac troponin I (hs-cTnI), high-sensitivity C-reactive protein (hs-CRP), and interleukin-6 (IL-6) were measured preoperatively and on POD 2. Patients were monitored for adverse events until POD 90.

RESULTS

Five hundred fifty-six patients were screened, 22 were recruited (4 hip Fx, 11 THR, 7 TKR), and 2 withdrew. Most (80%) had detectable hs-cTnI (> 1.1 pg/mL) preoperatively. Twenty percent had a perioperative rise in hs-cTnI (≥ 10 pg/mL), which was not blunted by atorvastatin. Hs-CRP rose in 19/20 patients, and IL-6 rose in all patients. However, atorvastatin did not blunt the rise in these inflammatory biomarkers. On POD 2, IL-6 and hs-cTnI levels correlated (ρ = 0.59, p = 0.02). Recruitment was limited by the high prevalence of statin use in the screened population and a high prevalence of exclusions among hip fracture patients.

CONCLUSION

Perioperative myocardial injury and inflammation are common in orthopedic patients and do not appear to be reduced in those randomized to atorvastatin.

TRIAL REGISTRATION

NCT02197065.

The Effect of Previous Coronary Artery Revascularization on the Adverse Cardiac Events Ninety days After Total Joint Arthroplasty

BACKGROUND

Although coronary artery revascularization therapies are effective for treating coronary artery disease (CAD), these patients may be more susceptible to adverse cardiac events during later non-cardiac surgeries. The purpose of this study is to evaluate post-operative 90-day complications of total joint arthroplasty (TJA) in CAD patients with a history of CAD and to study the risk factors for cardiac complications.

METHODS

We performed a retrospective analysis of TJA patients between 2005 and 2015 at our institute by summarizing the history of CAD, cardiac revascularization, and cardiac complications within 90 days after the operation. Multivariate logistic regression was performed to identify the factors that predicted cardiac complications within 90 days after the operation.

RESULTS

A total of 4414 patients were included; of these, 64 underwent cardiac revascularization and 201 CAD patients underwent medical therapy other than revascularization. All the revascularization had history of myocardial infarction (MI). The rate of cardiac complications within 90 days for the CAD with revascularization was 18.7%, 18.4% for the CAD without revascularization, and 2.0% for the non-CAD group. A history of CAD and revascularization, bilateral TJA, general anesthesia, body mass index ≥30 kg/m², and history of MI were associated with a higher risk of cardiac complications. Patients who underwent TJA within 2 years after cardiac revascularization had a significantly higher cardiac complication rate, and the risk decreased with time.

CONCLUSION

There is an increased risk of cardiac complications within 90 days after the operation among TJA patients with a history of CAD. Revascularization cannot significantly reduce the risk of cardiac complications after TJA for CAD patients. However, the risk decreased as the interval between revascularization and TJA increased.

Aspirin and the prevention of venous thromboembolism following total joint arthroplasty: commonly asked questions

The number of arthroplasties being performed increases each year. Patients undergoing an arthroplasty are at risk of venous thromboembolism (VTE) and appropriate prophylaxis has been recommended. However, the optimal protocol and the best agent to minimise VTE under these circumstances are not known. Although many agents may be used, there is a difference in their efficacy and the risk of bleeding. Thus, the selection of a particular agent relies on the balance between the desire to minimise VTE and the attempt to reduce the risk of bleeding, with its undesirable, and occasionally fatal, consequences.

Acetylsalicylic acid (aspirin) is an agent for VTE prophylaxis following arthroplasty. Many studies have shown its efficacy in minimising VTE under these circumstances. It is inexpensive and well-tolerated, and its use does not require routine blood tests. It is also a ‘milder’ agent and unlikely to result in haematoma formation, which may increase both the risk of infection and the need for further surgery. Aspirin is also unlikely to result in persistent wound drainage, which has been shown to be associated with the use of agents such as low-molecular-weight heparin (LMWH) and other more aggressive agents.

The main objective of this review was to summarise the current evidence relating to the efficacy of aspirin as a VTE prophylaxis following arthroplasty, and to address some of the common questions about its use.

There is convincing evidence that, taking all factors into account, aspirin is an effective, inexpensive, and safe form of VTE following arthroplasty in patients without a major risk factor for VTE, such as previous VTE.

Cite this article: Bone Joint J 2017;99-B:1420–30.

The Incidence of Perioperative Cardiac Events after Orthopedic Surgery: A Single Institutional Experience of Cases Performed over One Year

BACKGROUND

Orthopedic patients with ischemic heart disease are at risk for postoperative cardiac complications.

QUESTIONS/PURPOSES

Using information from two medical information retrieval systems which insured the capture of all events for the period of study, our goals were to determine the incidence of myocardial injury in at-risk patients after orthopedic surgery and to delineate the type and incidence of cardiac complications in this population.

METHODS

For one year, at an orthopedic hospital, we identified all postoperative patients with a measured cTnI level using an electronic ordering system. Preoperative cardiac risk factors and postoperative cardiac complications were identified in patients undergoing a total hip arthroplasty (THA), total knee arthroplasty (TKA), and posterior spinal fusion (PSF). A postoperative myocardial infarction was defined by a cTnI > 0.1 ng/mL, ECG changes, new echocardiographic regional wall motion abnormalities, and evaluation by a cardiologist. Categorical variables were compared among groups with a Fisher's exact or Chi-square test. Continuous variables were compared among groups with ANOVA or the Kruskal-Wallis test. The associations of cardiac risk factors with myocardial injury are expressed as odds ratios from logistic regression models.

RESULTS

During a one-year period, from 10,627 inpatient orthopedic procedures, 805 patients were identified as at risk for postoperative myocardial ischemia. A total of 20.6% (166/805) of these patients had elevated serum cTnI levels (cTnI > 0.02 ng/mL), and there were ten documented postoperative MIs (10/805; 1.2%). For the at-risk TKA, THA, or PSF patients, 19% (102/532) had elevated cTnI levels and 31% (32/102) had postoperative cardiac complications, including arrhythmias (56%), congestive heart failure (2%), and MI (1%). Adjusting for sex, age, BMI, cardiac risk factors, and medications (statins and β-blockers), PSF patients had 3.9 times the risk of myocardial injury (p = 0.003) compared to TKA patients and 4.2 times that of THA patients.

CONCLUSIONS

The incidence of postoperative myocardial ischemia after major orthopedic surgery in patients with cardiac risk factors is high (8.7%), but the incidence of documented myocardial infarctions and serious cardiac complications remains low (1.2-2%). Patients with higher postoperative cTnI releases were more likely to have cardiac complications, and some procedures (spinal fusions) placed the patients at a higher risk.

Lower limb arthroplasty: can we produce a tool to predict outcome and failure, and is it cost-effective? An epidemiological study

Background

Although hip and knee arthroplasties are considered to be common elective cost-effective operations, up to one-quarter of patients are not satisfied with the operation. A number of risk factors for implant failure are known, but little is known about the predictors of patient-reported outcomes.

Objectives

(1) Describe current and future needs for lower limb arthroplasties in the UK; (2) describe important risk factors for poor surgery outcomes and combine them to produce predictive tools (for hip and knee separately) for poor outcomes; (3) produce a Markov model to enable a detailed health economic analysis of hip/knee arthroplasty, and for implementing the predictive tool; and (4) test the practicality of the prediction tools in a pragmatic prospective cohort of lower limb arthroplasty.

Design

The programme was arranged into four work packages. The first three work packages used the data from large existing data sets such as Clinical Practice Research Datalink, Hospital Episode Statistics and the National Joint Registry. Work package 4 established a pragmatic cohort of lower limb arthroplasty to test the practicality of the predictive tools developed within the programme.

Results

The estimated number of total knee replacements (TKRs) and total hip replacements (THRs) performed in the UK in 2015 was 85,019 and 72,418, respectively. Between 1991 and 2006, the estimated age-standardised rates (per 100,000 person-years) for a THR increased from 60.3 to 144.6 for women and from 35.8 to 88.6 for men. The rates for TKR increased from 42.5 to 138.7 for women and from 28.7 to 99.4 for men. The strongest predictors for poor outcomes were preoperative pain/function scores, deprivation, age, mental health score and radiographic variable pattern of joint space narrowing. We found a weak association between body mass index (BMI) and outcomes; however, increased BMI did increase the risk of revision surgery (a 5-kg/m2rise in BMI increased THR revision risk by 10.4% and TKR revision risk by 7.7%). We also confirmed that osteoarthritis (OA) severity and migration pattern of the hip predicted patient-reported outcome measures. The hip predictive tool that we developed performed well, with a correctedR2of 23.1% and had good calibration, with only slight overestimation of Oxford Hip Score in the lowest decile of outcome. The knee tool developed performed less well, with a correctedR2of 20.2%; however, it had good calibration. The analysis was restricted by the relatively limited number of variables available in the extant data sets, something that could be addressed in future studies. We found that the use of bisphosphonates reduced the risk of revision knee and hip surgery by 46%. Hormone replacement therapy reduced the risk by 38%, if used for at least 6 months postoperatively. We found that an increased risk of postoperative fracture was prevented by bisphosphonate use. This result, being observational in nature, will require confirmation in a randomised controlled trial. The Markov model distinguished between outcome categories following primary and revision procedures. The resulting outcome prediction tool for THR and TKR reduced the number and proportion of unsatisfactory outcomes after the operation, saving NHS resources in the process. The highest savings per quality-adjusted life-year (QALY) forgone were reported from the oldest patient subgroups (men and women aged ≥ 80 years), with a reported incremental cost-effectiveness ratio of around £1200 saved per QALY forgone for THRs. In the prospective cohort of arthroplasty, the performance of the knee model was modest (R2 = 0.14) and that of the hip model poor (R2 = 0.04). However, the addition of the radiographic OA variable improved the performance of the hip model (R2 = 0.125 vs. 0.110) and high-sensitivity C-reactive protein improved the performance of the knee model (R2 = 0.230 vs. 0.216). These data will ideally need replication in an external cohort of a similar design. The data are not necessarily applicable to other health systems or countries.

Conclusion

The number of total hip and knee replacements will increase in the next decade. High BMI, although clinically insignificant, is associated with an increased risk of revision surgery and postoperative complications. Preoperative pain/function, the pattern of joint space narrowing, deprivation index and level of education were found to be the strongest predictors for THR. Bisphosphonates and hormone therapy proved to be beneficial for patients undergoing lower limb replacement. The addition of new predictors collected from the prospective cohort of arthroplasty slightly improved the performance of the predictive tools, suggesting that the potential improvements in both tools can be achieved using the plethora of extra variables from the validation cohort. Although currently it would not be cost-effective to implement the predictive tools in a health-care setting, we feel that the addition of extensive risk factors will improve the performances of the predictive tools as well as the Markov model, and will prove to be beneficial in terms of cost-effectiveness. Future analyses are under way and awaiting more promising provisional results.

Future work

Further research should focus on defining and predicting the most important outcome to the patient.

Funding

The National Institute for Health Research Programme Grants for Applied Research programme.

Characteristics of Orthopedic Publications in High-Impact General Medical Journals

Orthopedic studies are occasionally published in high-impact general medical journals; these studies are often given high visibility and have significant potential to impact health care policy and inform clinical decision-making. The purpose of this review was to investigate the characteristics of operative orthopedic studies published in high-impact medical journals. The number of orthopedic studies published in high-impact medical journals is relatively low; however, these studies demonstrate methodological characteristics that may bias toward nonoperative treatment. Careful analysis and interpretation of orthopedic studies published in these journals is warranted. [Orthopedics. 2017; 40(3):e405-e412.].

Myocardial Infarction Risk in Arthroplasty vs Arthroscopy: How Much Does Procedure Type Matter?

BACKGROUND

This study aimed at assessing short-term risk of serious cardiac events after elective total joint arthroplasty (TJA) as compared to a less-invasive procedure, knee arthroscopy (KA).

METHODS

Patients who underwent elective primary total hip arthroplasty (THA), total knee arthroplasty (TKA), or KA from 2011 to 2014 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. A 1:1 propensity matching was used to generate 2 control cohorts of KA patients with similar characteristics. Bivariate and multivariate analyses were assessed using perioperative variables.

RESULTS

A total of 24,203 THA, 21,740 TKA, and 45,943 KA patients were included. Bivariate analysis revealed significantly higher rates of serious 30-day cardiac events (myocardial infarction or cardiac arrest) among THA (0.15% vs 0.05%, P < .001) and TKA patients (0.14% vs 0.05%, P < .03) vs KA controls. In multivariate analysis controlling for patient characteristics and comorbidities, THA and TKA were associated with a 2.61 and 1.98 times odds of serious 30-day cardiac events as compared to controls (P ≤ .03 for both). Additional independent predictors of serious 30-day cardiac events included age, smoking, cardiac disease, and American Society of Anesthesiologists class 3/4. In the THA and TKA cohorts, serious cardiac events occurred within the first 3 days postoperation compared to 4 days in controls.

CONCLUSION

After controlling for patient characteristics and comorbidities, TJA increased the short-term risk of serious cardiac event compared to a less-invasive procedure. This information better quantifies the risk differential for patients considering surgery as they engage in shared decision making with their providers. In addition, our data may have an impact on perioperative management of antithrombotic medications used in patients with cardiac disease. The median time in days to serious cardiac event was 2 in THA and 3 in TKA vs 4 in KA, which may have implications in postoperative monitoring of patients after surgery.

Orthopedic surgery increases atherosclerotic lesions and necrotic core area in ApoE-/- mice

BACKGROUND AND AIMS

Observational studies show a peak incidence of cardiovascular events after major surgery. For example, the risk of myocardial infarction increases 25-fold early after hip replacement. The acuteness of this increased risk suggests abrupt enhancement in plaque vulnerability, which may be related to intra-plaque inflammation, thinner fibrous cap and/or necrotic core expansion. We hypothesized that acute systemic inflammation following major orthopedic surgery induces such changes.

METHODS

ApoE^-/- mice were fed a western diet for 10 weeks. Thereafter, half the mice underwent mid-shaft femur osteotomy followed by realignment with an intramedullary K-wire, to mimic major orthopedic surgery. Mice were sacrificed 5 or 15 days post-surgery (n = 22) or post-saline injection (n = 13). Serum amyloid A (SAA) was measured as a marker of systemic inflammation. Paraffin embedded slides of the aortic root were stained to measure total plaque area and to quantify fibrosis, calcification, necrotic core, and inflammatory cells.

RESULTS

Surgery mice showed a pronounced elevation of serum amyloid A (SAA) and developed increased plaque and necrotic core area already at 5 days, which reached significance at 15 days (p = 0.019; p = 0.004 for plaque and necrotic core, respectively). Macrophage and lymphocyte density significantly decreased in the surgery group compared to the control group at 15 days (p = 0.037; p = 0.024, respectively). The density of neutrophils and mast cells remained unchanged.

CONCLUSIONS

Major orthopedic surgery in ApoE-/- mice triggers a systemic inflammatory response. Atherosclerotic plaque area is enlarged after surgery mainly due to an increase of the necrotic core. The role of intra-plaque inflammation in this response to surgical injury remains to be fully elucidated.

Perioperative antiplatelet therapy and cardiovascular outcomes in patients undergoing joint and spine surgery

STUDY OBJECTIVE

Perioperative thrombotic complications after orthopedic surgery are associated with significant morbidity and mortality. The use of aspirin to reduce perioperative cardiovascular complications in certain high-risk cohorts remains controversial. Few studies have addressed aspirin use, bleeding, and cardiovascular outcomes among high-risk patients undergoing joint and spine surgery.

DESIGN/SETTING/PATIENTS

We performed a retrospective comparison of adults undergoing knee, hip, or spine surgery at a tertiary care center during 2 periods between November 2008 and December 2009 (reference period) and between April 2013 and December 2013 (contemporary period).

MEASUREMENTS

Patient demographics, comorbidities, management, and outcomes were ascertained using hospital datasets.

MAIN RESULTS

A total of 5690 participants underwent 3075 joint and spine surgeries in the reference period and 2791 surgeries in the contemporary period. Mean age was 61±13 years, and 59% were female. In the overall population, incidence of myocardial injury (3.1% vs 5.8%, P<.0001), hemorrhage (0.2% vs 0.8%, P=.0009), and red blood cell transfusion (17.2% vs 24.8%, P<.001) were lower in the contemporary period. Among 614 participants with a preoperative diagnosis of coronary artery disease (CAD), in-hospital aspirin use was significantly higher in the contemporary period (66% vs 30.7%, P<.0001); numerically, fewer participants developed myocardial injury (13.5% vs 19.3%, P=.05), had hemorrhage (0.3% vs 2.1%, P=.0009), and had red blood cell transfusion (37.2% vs 44.2%, P<.001) in the contemporary vs reference period.

CONCLUSIONS

In a large tertiary care center, the incidence of perioperative bleeding and cardiovascular events decreased over time. In participants with CAD, perioperative aspirin use increased and appears to be safe.

Statins and Risk of Lower Limb Revision Surgery: The Influence of Differences in Study Design Using Electronic Health Records From the United Kingdom and Denmark

Previous observational studies on statins have shown variable results based on the methodology used. Our objective was to study the association between statins and orthopedic implant failure and to explore the influence of methodological differences in study design. Our study base consisted of patients with a primary total joint replacement in Denmark and the United Kingdom (n = 189,286; 1987–2012). We used 4 study designs: 1) case-control (each patient with revision surgery matched to 4 controls), 2) time-dependent cohort (postoperative statin use as a time-varying exposure variable), 3) immortal time cohort (misclassifying the time postoperatively before statin use), and 4) time-exclusion cohort (excluding the time postoperatively before statin use). Cox proportional hazards models and logistic regression were used to estimate incidence rate ratios. In the time-dependent cohort design, statin use was associated with a decreased risk of revision surgery (adjusted incidence rate ratio (IRR) = 0.90, 95% confidence interval (CI): 0.85, 0.96), which was similar to our case-control results (IRR = 0.87, 95% CI: 0.81, 0.93). In contrast, both time-fixed cohort designs yielded substantially lower risk estimates (IRR = 0.36 (95% CI: 0.34, 0.38) and IRR = 0.65 (95% CI: 0.63, 0.68), respectively). We discourage the use of time-fixed cohort studies, which may falsely suggest protective effects. The simple choice of how to classify exposure can substantially change results from biologically plausible to implausible.

Risk of hip, subtrochanteric, and femoral shaft fractures among mid and long term users of alendronate: nationwide cohort and nested case-control study

OBJECTIVES

 To determine the skeletal safety and efficacy of long term (≥10 years) alendronate use in patients with osteoporosis.

DESIGN

 Open register based cohort study containing two nested case control studies.

SETTING

 Nationwide study of population of Denmark.

PARTICIPANTS

 61 990 men and women aged 50-94 at the start of treatment, who had not previously taken alendronate, 1996-2007.

INTERVENTIONS

 Treatment with alendronate.

MAIN OUTCOME MEASURES

 Incident fracture of the subtrochanteric femur or femoral shaft (ST/FS) or the hip. Non-fracture controls from the cohort were matched to fracture cases by sex, year of birth, and year of initiation of alendronate treatment. Conditional logistic regression models were fitted to calculate odds ratios with and without adjustment for comorbidity and comedications. Sensitivity analyses investigated subsequent treatment with other drugs for osteoporosis.

RESULTS

 1428 participants sustained a ST/FS (incidence rate 3.4/1000 person years, 95% confidence interval 3.2 to 3.6), and 6784 sustained a hip fracture (16.2/1000 person years, 15.8 to 16.6). The risk of ST/FS was lower with high adherence to treatment with alendronate (medication possession ratio (MPR, a proxy for compliance) >80%) compared with poor adherence (MPR <50%; odds ratio 0.88, 0.77 to 0.99; P=0.05). Multivariable adjustment attenuated this association (adjusted odds ratio 0.88, 0.77 to 1.01; P=0.08). The risk was no higher in long term users (≥10 dose years; 0.70, 0.44 to 1.11; P=0.13) or in current compared with past users (0.91, 0.79 to 1.06; P=0.22). Similarly, MPR >80% was associated with a decreased risk of hip fracture (0.73, 0.68 to 0.78; P<0.001) as was longer term cumulative use for 5-10 dose years (0.74, 0.67 to 0.83; P<0.001) or ≥10 dose years (0.74, 0.56 to 0.97; P=0.03).

CONCLUSIONS

 These findings support an acceptable balance between benefit and risk with treatment with alendronate in terms of fracture outcomes, even for over 10 years of continuous use.

The Association of Anemia and Its Severity with Cardiac Outcomes and Mortality After Total Knee Arthroplasty in Noncardiac Patients

BACKGROUND

The purpose of this study is to assess whether an association exists between preoperative anemia and postoperative cardiac events or death in patients undergoing unilateral primary total knee arthroplasty (TKA) with no prior cardiac history.

METHODS

Data from the 2008-2012 American College of Surgeons National Surgical Quality Improvement Program database were analyzed. Patients aged ≥18 years undergoing unilateral primary TKA were included. We divided the patients into 4 groups: no anemia, any anemia, mild anemia, and moderate-severe anemia. Associations between anemia and different characteristics as well as cardiac outcomes and death were studied, after adjusting for all potential confounders.

RESULTS

In the nonanemic group, the occurrence of myocardial infarction, cardiac arrest, and death were 61 of 34,661 (0.18%), 23 of 34,661 (0.07%), and 30 of 34,661 (0.09%), respectively. The numbers in the anemia group were 23 of 6673 (0.34%), 9 of 6673 (0.13%), and 14 of 6673 (0.21%). These were not statistically different. The anemic group had higher odds for respiratory and renal morbidities and for receiving transfusions.

CONCLUSION

We found no association between preoperative anemia or its severity and myocardial infarction, cardiac arrest, or death up to 30 days postoperatively. This could potentially lower the bar for safe preoperative hematocrit levels for elective TKA, theoretically increasing the percentage of anemic patients undergoing the procedure. This, however, is at the expense of potential respiratory and renal insults.

A National Analysis of Complications Following Total Hip Replacement in Patients With Chronic Obstructive Pulmonary Disease

Patients with chronic obstructive pulmonary disease (COPD) have a high risk of osteoporosis and fractures. The incidence rate of hip fracture has steadily increased over time and is a major common event in patients with osteoporosis and COPD. Total hip replacement (THR) is commonly performed in patients with hip fracture. Our aim was to compare the complications of THR between patients with and without COPD.Longitudinally linked data from the National Health Insurance Research Database, which consists of registration, claims, and reimbursement records, for a cohort of 1,000,000 randomly selected enrollees traced retrospectively from 1996 to 2000 in Taiwan. Patients who had undergone THR surgery between January 1, 2004, and December 31, 2008, were identified and divided into COPD and non-COPD cohorts. Outcomes and complications, including 90-day mortality, 1-year mortality, 1-year wound infection, 30-day readmission for hospitalization, 30-day pneumonia, 30-day acute respiratory failure, 30-day cerebrovascular accident, and length of stay during hospitalization, were measured after THR.The COPD group had a significantly higher ratio of complications, including 30-day readmission (14.0% vs 8.4%), 30-day pneumonia (10.4% vs 4.4%), 30-day acute respiratory failure (1.5% vs 0.5%), 1-year mortality (6.9% vs 2.7%), and length of stay in the hospital (10.6% vs 0.8%) than the non-COPD group.In addition to airway diseases, patients in the COPD group had higher mortality than those in non-COPD group after THR. Surgeons should give more attention to airway evaluation and selection of patients with COPD for THR.

The effects of advanced age on primary total knee arthroplasty: a meta-analysis and systematic review

Background

Total knee arthroplasty is an effective treatment when nonsurgical treatments fail, but it is associated with risk of complications which may be increased in advanced age. The purpose of this study was to quantify age-related differences in perioperative morbidity and mortality after total knee arthroplasty through systematic review of existing literature.

Methods

PubMed, the Cochrane database of systematic reviews, Scopus, and clinicaltrials.gov, were queried for relevant studies that compared primary total knee arthroplasty outcomes of mortality, myocardial infarction (MI), deep vein thrombosis (DVT), pulmonary embolism (PE) and functional status, of geriatric patients (>75 years old) with a younger control group (<65 years old). Pertinent journals and reference lists were hand searched. Eligibility criteria included all articles except case reports, meta-analyses, and systematic reviews. Two authors independently extracted data from each paper. Article quality was assessed using the Newcastle-Ottawa Scale.

Results

Twenty-two studies were included. Geriatric patients had higher rates of mortality, MI, DVT, and length of stay in older compared to younger patients, however the absolute magnitude of these increases were small. The increase in mortality may have reflected decreased life expectancy in the geriatric populations as opposed to mortality specifically due perioperative risk. There were no differences in PE incidence and improvement in pain and functional status was equal in older and younger patients. Existing studies were limited by non-randomized patient selection, as well as variation in definitions and methodology.

Conclusions

Existing data supports offering primary total knee arthroplasty to select geriatric patients, although the risk of complications may be increased. Much of the data was of poor quality. Future prospective studies are needed to better identify risks and benefits of total knee arthroplasty so that patients and surgeons can make informed decisions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-016-0215-4) contains supplementary material, which is available to authorized users.

Risk of Post-TKA Acute Myocardial Infarction in Patients With a History of Myocardial Infarction or Coronary Stent

BACKGROUND

Acute myocardial infarction (AMI) is one of the most important perioperative complications of total knee arthroplasty (TKA). Although risk-stratification tools exist for the prediction of cardiac complications including AMI after noncardiac surgery, such stratification does not differentiate the patients with a coronary stent alone, AMI without a stent, or AMI with a stent. The risk of postoperative AMI in these patient groups may vary. Several studies have recommended suitable times for noncardiac surgery in patients with a coronary stent; however, they do not differentiate between the patients with AMI and no AMI. The suitable time of noncardiac surgery for patients with AMI and stent may vary from those with a stent alone. Moreover, a study to evaluate the risk of AMI within 1 year in an Asian population with a history of AMI or coronary stent who underwent TKA has not been reported.

QUESTIONS/PURPOSES

(1) What are the risks of AMI within 1 year of TKA in patients who have had a stent alone, AMI without a stent, or AMI with a stent as compared with patients without an AMI/stent? (2) For patients with AMI/stent placement, when can TKA be performed where the risk of subsequent AMI normalizes? (3) What comorbidities are associated with post-TKA AMI? (4) Is the risk of AMI within 1 year after surgery in patients undergoing TKA without a history of AMI/stent higher than that in patients with no surgery?

METHODS

This study is a retrospective study of the medical claim records of 128,216 patients who underwent TKA between 1997 and 2010 in Taiwan. The records were retrieved from the research database of the Bureau of National Health Insurance in Taiwan, which maintains the records of 99.68% of the Taiwan population. The patients who had a history of AMI or coronary stent placement within the year before TKA were compared with the patients who had not experienced AMI or stent placement before TKA. The control subjects were matched according to sex, age, Charlson score, and year of surgery. There were 2413 patients in each group. The patients with a history of AMI or stent placement and the timing of TKA after coronary event were further stratified as with a coronary stent alone, AMI without a stent, and AMI with a stent. The effects of the comorbidities of renal failure, diabetes, liver failure, and hypertension were also analyzed individually. The risk of AMI within 1 year after TKA was investigated using bivariate analysis and the Cox proportional hazard model. To compare the risk of AMI within 1 year of surgery in the patients with a history of TKA and no AMI/stent with the population without a history of surgery, a similar bivariate analysis and the Cox proportional hazard model were applied to their matched case and control groups, each containing 110,980 patients.

RESULTS

In the adjusted model, using no AMI/stent before TKA as a reference, patients having undergone AMI + stent had the highest risk (hazard ratio [HR], 5.23; 95% confidence interval [CI], 1.81-15.14; p = 0.002), AMI alone without a stent had less risk (HR, 4.88; 95% CI, 1.49-16.01; p = 0.009), and stent alone with AMI had the lowest risk (HR, 3.16; 95% CI, 1.29-7.71; p = 0.012). In all patients, risk of AMI after TKA was not different than reference values after 1 year of initial AMI or stent (stent: HR, 1.67; 95% CI, 0.71-3.94; p = 0.239; AMI: HR, 1.88; 95% CI, 0.42-8.49; p = 0.412; AMI + stent: HR, 1.91; 95% CI, 0.53-6.89; p = 0.321). The risk of post-TKA AMI was elevated within 1 year of the previous episode of AMI/stent (0-180 days: HR, 8.42; 95% CI, 3.03-23.41; p < 0.001; 181-365 days: HR, 7.52; 95% CI, 2.47-22.88; p < 0.001). Only chronic renal failure under hemodialysis was associated with increased risk of AMI within 1 year of TKA (adjusted HR, 4.34; 95% CI, 1.22-15.43; p = 0.023). Patients undergoing TKA with no history of AMI/stent had a lower risk of AMI within 1 year of TKA compared with the patients with no history of surgery (adjusted HR, 0.92; 95% CI, 0.86-0.99; p = 0.016).

CONCLUSIONS

This study found the risk of post-TKA AMI remains high within 1 year in patients with a history of AMI/stent. It is recommended that an elective TKA should be performed at least 1 year after an episode of AMI or stent placement. Stents do not provide protection against post-TKA AMI within 6 months of the AMI and patients with AMI + stent have a higher risk of AMI than those with only AMI. Patients of AMI/stent on hemodialysis have a very high risk of post-TKA AMI. However, the risk of AMI is lower in post-TKA patients compared with those with no TKA.

LEVEL OF EVIDENCE

Level III, prognostic study.

Early thromboembolic events ≤1week after fast-track total hip and knee arthroplasty

INTRODUCTION

Thromboembolic events (TEE) are serious complications after total hip (THA) and knee arthroplasty (TKA), with reported in-hospital incidences of about 0.5-1% for venous thromboembolic events (VTE) and 0.2% for myocardial infarctions (MI) and stroke. However, little data exist on in-hospital TEE when using a standardized fast-track protocol with early mobilization.

MATERIALS AND METHODS

A large detailed cohort study in primary unilateral THA and TKAs on "early" (in-hospital or after discharge but within 1week of surgery) and 30-days TEEs, including prospective recording of patient characteristics, complete follow-up through the Danish National Patient Register, and detailed evaluation on disposing factors and consequences of "early" TEEs through review of medical records.

RESULTS

In 13,775 procedures with a median LOS of 2days, 43 (0.32%; 95% CI: 0.23-0.42) "early" and 90 (0.65%; 95% CI: 0.53-0.80) 30-day TEEs were recorded. "Early" TEEs consisted of 9 (0.07%; 95% CI: 0.04-0.13) MI, 10 (0.08% 95% CI: 0.04-0.13) strokes, 13 (0.09%; 95% CI: 0.05-0.16) pulmonary embolisms and 11 (0.08%; 95% CI: 0.04-0.15) deep venous thromboses. Most TEEs were in patients with irreversible dispositions (e.g. previous TEE, high age and cardiac disease), but 5 of 9 MIs were associated with postoperative anemia. All in-hospital VTE (n: 16) occurred while patients received recommended thromboprophylaxis.

CONCLUSIONS

Incidence of "early" TEEs after fast-track THA and THA is low, but MIs may be further reduced by improving perioperative treatment of anemia. Further research is needed regarding interventions for prevention of "early" TEE in disposed patients.

Total joint arthroplasty and the risk of myocardial infarction: a general population, propensity score-matched cohort study

OBJECTIVE

To replicate recent findings indicating that total knee arthroplasty (TKA) or total hip arthroplasty (THA) surgery will substantially reduce the risk of serious cardiovascular events among patients with osteoarthritis.

METHODS

A time-stratified, propensity score-matched cohort study was conducted to assess the incidence of myocardial infarction (MI) in a UK general population. The study population included individuals ages ≥50 years who had a UK National Health Service READ code diagnosis of knee osteoarthritis (to evaluate TKA) or hip osteoarthritis (to evaluate THA) between January 2000 and December 2012.

RESULTS

Among the patients who underwent TKA and their matched non-TKA control subjects (each n = 13,849), 306 patients and 286 control subjects developed MI during the followup. During the first postoperative month, the risk of MI was substantially increased among the TKA group compared with the non-TKA group (hazard ratio [HR] 8.75, 95% confidence interval [95% CI] 3.11-24.62), and then gradually declined during the subsequent followup. The HR for the risk of MI over the entire followup was 0.98 (95% CI 0.82-1.18). The corresponding HRs for the risk of MI in those who had undergone THA compared with the non-THA group (each n = 6,063) were 4.33 (95% CI 1.24-15.21) in the first postoperative month and 0.87 (95% CI 0.66-1.15) overall. In analyses using venous thromboembolism as a positive control outcome, both the first month and overall HRs for the risk of venous thromboembolism were substantially increased in both the TKA and THA groups.

CONCLUSION

These findings provide the first general population-based evidence to indicate that TKA and THA among osteoarthritis patients are associated with a substantially increased risk of MI during the immediate postoperative period. However, the overall long-term impact of these surgeries was null, unlike the risk of venous thromboembolism, which remained elevated years after patients had undergone the procedure.

Is there a link between the neutrophil-to-lymphocyte ratio and venous thromboembolic events after knee arthroplasty? A pilot study

Background

This study aimed to identify (1) if the postoperative increase in the neutrophil-to-lymphocyte ratio (NLR) is different between contrasting knee arthroplasty procedures, and (2) if the NLR predicts venous thromboembolism (VTE) after total knee arthroplasty (TKA).

Materials and methods

To address the first objective, we retrospectively studied patients who underwent primary unilateral TKA (n = 111) or unicompartmental knee arthroplasty (UKA; n = 74) between 2009 and 2012. Patients who required a blood transfusion, underwent autologous blood salvage, experienced any postoperative complication (such as VTE), or were re-admitted >90 days were excluded from analysis. For the second objective, we retrospectively identified patients (cases, n = 10) who underwent primary unilateral TKA between 2010 and 2012 and developed postoperative VTE (deep venous thrombosis, pulmonary embolism, or both) during inpatient care (postoperative day 1 or day 2). Cases were matched to surgeon, gender, body mass index, age, and date of surgery controls (n = 20) who underwent primary unilateral TKA without developing VTE before patient discharge. The NLR was calculated from the neutrophil and lymphocyte counts extracted from pre- and postoperative (day 1 and day 2) blood chemistry records.

Results

On postoperative day 1, the NLR increase was exacerbated (p = 0.02) following TKA compared to UKA and predicted (p = 0.02) the occurrence of VTE in TKA patients prior to hospital discharge.

Conclusion

We conclude that the NLR increase is greater following TKA compared to UKA and could serve as a matrix to predict or identify a patient susceptible of sustaining VTE after TKA.

Level of evidence

3.

Inpatient versus outpatient onsets of acute myocardial infarction

BACKGROUND

There are few studies on patients suffering acute myocardial infarction (AMI) when already in hospital for other reasons; therefore, this study aimed to compare patients with in-hospital-onset AMI admitted for either medical or surgical reasons versus patients with outpatient-onset AMI.

METHODS

Patients enrolled in the AMIS Plus registry from 2002 to 2014 were analyzed. The main endpoint was in-hospital mortality.

RESULTS

Among 35,394 AMI patients, 356 (1%) had inpatient-onset AMI following hospital admission due to other pathologies (surgical 175, non-surgical 181). These patients were older (74 vs. 66 years; P<0.001), more often female (35% vs. 27%; P<0.001), had less frequently ST-elevation myocardial infarction (35.5% vs. 55.5%; P<0.001), but higher risk profiles: hypertension (83% vs. 62%; P<0.001), diabetes (28% vs. 20%; P=0.001), known coronary artery disease (54% vs. 35%; P<0.001), and more comorbidities (Charlson Comorbidity Index above 1 in 51% vs. 22%; P<0.001) than those with outpatient-onset AMI. Percutaneous coronary intervention was less frequently applied (OR 0.45; 95% CI 0.36-0.57), and they were less likely to be treated with aspirin (OR 0.43; 95% CI 0.37-0.59), P2Y12 blockers (OR 0.42; 0.34-0.52) or statins (OR 0.51; 95% CI 0.41-0.63). Crude mortality was higher (14.3% vs. 5.5%; P<0.001) and inpatient-onset AMI was an independent predictor of in-hospital mortality (OR 2.35; 95% CI 1.63-3.39; P<0.001).

CONCLUSIONS

Patients with in-hospital-onset AMI were at greater risk of death than those with outpatient-onset AMI. More work is needed to improve the identification of hospitalized patients at risk of AMI in order to provide the appropriate management.

Post-operative arterial thrombosis with non-vitamin K antagonist oral anticoagulants after total hip or knee arthroplasty

The incidence of post-operative arterial thrombosis (AT) (acute myocardial infarction [AMI] and ischaemic stroke) is increased in patients undergoing total hip replacement (THR) or total knee replacement (TKR). We compared the incidence of post-operative AT in non-vitamin K antagonist oral anticoagulants (NOACs)-treated and enoxaparin-treated patients, performing a systematic review of phase III randomised controlled trials (RCTs) of venous thromboembolism (VTE) prophylaxis in THR and TKR. Studies were identified by electronic search of MEDLINE and EMBASE database until July 2014. Differences between NOACs and enoxaparin groups in the efficacy and safety outcomes were expressed as odds ratios (ORs) with pertinent 95 % confidence intervals (95 % CI). Statistical heterogeneity was assessed with the I² statistic. Eleven phase III RCTs for a total of 31,319 patients were included. Patients underwent TKR in six studies and THR in five studies. The NOACs under study were dabigatran (four studies), apixaban (three studies) and rivaroxaban (four studies). AT occurred in 0.23 % of patients on NOACs and in 0.27 % of patients on enoxaparin: the OR at fixed-effect model was 0.86 (95 % CI 0.53-1.40; I² 11 %). No differences in AT incidence among the three NOACs were observed. The incidence of major and clinically relevant bleeding was similar in NOACs and enoxaparin groups (OR 1.03, 95 % CI 0.92-1.15; I² 38 %). In conclusion, in RCTs of pharmacological VTE prophylaxis in patients undergoing THR or TKR, there was no difference in the incidence of post-operative AT among patients treated with NOACs, compared to those treated with enoxaparin.

Effects of Computer Navigation versus Conventional Total Knee Arthroplasty on Endothelial Damage Marker Levels: A Prospective Comparative Study

Total knee arthroplasty (TKA) inevitably perturbs the femoral medullary canal, which increases blood loss or morbidities associated with marrow embolization postoperatively. Computer navigation TKA reportedly minimizes medullary disturbance to alleviate perioperative blood loss. We performed a prospective comparative study, enrolling 87 patients with osteoarthritic knees from March 2011 to December 2011 in our hospital. The patients were separated into two groups, according to the surgeon they visited. Fifty-four patients underwent computer navigation TKAs and 33 had conventional TKAs. Levels of cell adhesion molecules (CAMs), including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), and platelet endothelial cellular adhesion molecule-1 (PECAM-1) in sera and hemovac drainage were measured by ELISA before and 24 hours after the surgery. We showed that patients receiving computer navigation TKAs had less blood loss and lower CAMs in serum and hemovac drainage after the operation. Less postoperative elevation of serum ICAM-1 (p=0.022) and PECAM-1 (p=0.003) from the preoperative baseline after the surgery was also noted. This study provides molecular evidence for the differential extent in vascular injury between conventional and navigation TKAs and sheds light on the possible benefits of computer navigation TKAs.

Effectiveness and safety of different duration of thromboprophylaxis in 16,865 hip replacement patients--a real-word, prospective observational study

INTRODUCTION

Clinical trials have provided evidence about efficacy and safety of extended thromboprophylaxis among total hip replacement (THR) patients. There is a lack of evidence on effectiveness and safety of extended treatment in unselected patients from routine clinical practice. We examined the effectiveness and safety of short (1-6 days) and standard (7-27 days) compared with extended (≥28 days) thromboprophylaxis using population-based design.

MATERIAL AND METHODS

Among all primary THR procedures performed in Denmark from 2010 through 2012 (n=16,865), we calculated adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs) for risk of symptomatic venous thromboembolism (VTE) and major bleeding, in addition to net clinical benefit, defined as the number of VTE avoided minus the number of excess bleeding events occurring among patients prescribed short-term and standard versus extended treatment.

RESULTS

The 90-day risks of VTE were 1.1% (short), 1.4% (standard), and 1.0% (extended), yielding aHRs of 0.83 (95% CI: 0.52-1.31) and 0.82 (95% CI: 0.50-1.33) for short and standard versus extended treatment. The risk of major bleeding was 1.1% (short), 1.0% (standard), and 0.7% (extended), resulting in aHRs of 1.64 (95% CI: 0.83-3.21) and 1.24 (95%CI: 0.61-2.51) for short and standard versus extended thromboprophylaxis. Direct comparison between benefits and harms using net clinical benefit analyses did not favor any of the three treatment durations. The same results were found for VTE or death.

CONCLUSIONS

In a real-word observational cohort of unselected THR patients, we observed no difference in the risks of symptomatic VTE, VTE/ death or bleeding with respect to thromboprophylaxis duration.

The effect of osteoarthritis on 1-year risk of ischemic heart disease following total knee arthroplasty

To evaluate the long-term risk of ischemic heart disease (IHD) following total knee arthroplasty (TKA), we conducted a retrospective cohort study using data from the National Health Insurance Research Database of Taiwan. We evaluated 3599 primary TKA patients and 14,396 matched control patients. We further classified all patients into those with and without osteoarthritis (OA). The incidence rate of IHD was significantly higher among the TKA patients than among the matched control patients (1.13 vs 0.69 per 1000 person-months, P<.05). However, after controlling for OA, this difference was non-significant (HR=1.18, 95% confidence interval (CI): 0.63-2.20, P>.05). Our study results indicate that underlying OA conditions are predominantly responsible for increased long-term risk of IHD in TKA patients.

Morbidity and mortality in the thirty-day period following total hip arthroplasty: risk factors and incidence

The study sought to ascertain the incidence rates and risk factors for 30-day post-operative complications after primary total hip arthroplasty (THA). Complications were categorized as systemic or local and subcategorized as major or minor. There were 17,640 individuals who received primary THA identified from the 2006-2011 ACS NSQIP. The mortality rate was 0.35% and complications occurred in 4.9%. Age groups ≥ 80 years (P <0.001) and 70-79 years old (P = 0.003), and renal insufficiency (P = 0.02) best predicted mortality. Age ≥80 years (P <0.001) and cardiac disease (P = 0.01) were the strongest predictors of developing any postoperative complication. Morbid obesity (P <0.001) and operative time > 141 minutes (P <0.001) were strongly associated with the development of major local complications.

Efficacy of autologous bone marrow concentrate for knee osteoarthritis with and without adipose graft

Introduction. We investigated the use of autologous bone marrow concentrate (BMC) with and without an adipose graft, for treatment of knee osteoarthritis (OA). Methods. Treatment registry data for patients who underwent BMC procedures with and without an adipose graft were analyzed. Pre- and posttreatment outcomes of interest included the lower extremity functional scale (LEFS), the numerical pain scale (NPS), and a subjective percentage improvement rating. Multivariate analyses were performed to examine the effects of treatment type adjusting for potential confounding factors. The frequency and type of adverse events (AE) were also examined. Results. 840 procedures were performed, 616 without and 224 with adipose graft. The mean LEFS score increased by 7.9 and 9.8 in the two groups (out of 80), respectively, and the mean NPS score decreased from 4 to 2.6 and from 4.3 to 3 in the two groups, respectively. AE rates were 6% and 8.9% in the two groups, respectively. Although pre- and posttreatment improvements were statistically significant, the differences between the groups were not. Conclusion. BMC injections for knee OA showed encouraging outcomes and a low rate of AEs. Addition of an adipose graft to the BMC did not provide a detectible benefit over BMC alone.

The effect of body mass index on the risk of post-operative complications during the 6 months following total hip replacement or total knee replacement surgery

OBJECTIVE

To assess the effect of obesity on 6-month post-operative complications following total knee (TKR) or hip (THR) replacement.

DESIGN

Data for patients undergoing first THR or TKR between 1995 and 2011 was taken from the Clinical Practice Research Datalink. Logistic regression was used to assess whether body mass index (BMI) was associated with 6-month post-operative complications [deep vein thrombosis or pulmonary embolism (DVT/PE), myocardial infarction (MI), stroke, respiratory infection, anaemia, wound infection, urinary tract infection or death] after controlling for the effects of age, gender, smoking, drinking, socio-economic status (SES), co-morbidities and medications.

RESULTS

31,817 THR patients and 32,485 TKR patients were identified for inclusion. Increasing BMI was associated with a significantly higher risk of wound infections, from 1.6% to 3.5% in THR patients (adjusted P < 0.01), and from 3% to 4.1% (adjusted P < 0.05) in TKR patients. DVT/PE risk also increased with obesity from 2.2% to 3.3% (adjusted P < 0.01) in THR patients and from 2.0% to 3.3% (adjusted P < 0.01) in TKR patients. Obesity was not associated with increased risk of other complications.

CONCLUSION

Whilst an increased risk of wound infection and DVT/PE was observed amongst obese patients, absolute risks remain low and no such association was observed for MI, stroke and mortality. However this is a selected cohort (eligible for surgery according to judgement of NHS GPs and surgeons) and as such these results do not advocate surgery be given without consideration of BMI, but indicate that universal denial of surgery based on BMI is unwarranted.

Policy encouraging earlier hip fracture surgery can decrease the long-term mortality of elderly patients

BACKGROUND

In April 2004 the Israeli Ministry of Health decided to condition DRG payment for hip surgery by time between hospitalisation and operation, giving a fine for every day's delay beyond 48h. An evaluation study performed 2 years after the reform has shown the positive influence of the reform on patient's survival in the hospital. This study evaluates the impact of the reform on the longer-term mortality of patients.

METHODS

A retrospective study based on data from nine hospitals of the national trauma registry available for the years 2001-2007, with surveillance on 2-year survival through data of Ministry of the Interior. The study population includes patients aged 65 and above with an isolated hip fracture following trauma. Mortality curves and Cox regression were utilised to compare the influence of different parameters on long-term mortality.

RESULTS

Earlier surgery had a significant positive impact on survival through the whole length of the study period. In the period after the introduction of the new reimbursement system for hip fracture surgeries, a significant decrease in the longer-term mortality was observed up to 6 months of follow-up, even when adjusted by patients' age, gender and the receiving hospital. After 6 months there was no further decrease in relative risk, though the survival advantage remained with patients hospitalised after the reform.

CONCLUSIONS

The reform appears successful in decreasing the longer-term patient mortality after hip fracture through influencing surgical practice.