Alejandro González Della Valle

Perioperative outcomes after unilateral and bilateral total knee arthroplasty

Background:The safety of bilateral total knee arthroplasties (BTKAs) during the same hospitalization remains controversial. The authors sought to study differences in perioperative outcomes between unilateral and BTKA and to further compare BTKAs performed during the same versus different operations during the same hospitalization. Methods:Nationwide Inpatient Sample data from 1998 to 2006 were analyzed. Entries for unilateral and BTKA procedures performed on the same day (simultaneous) and separate days (staged) during the same hospitalization were identified. Patient and healthcare system–related demographics were determined. The incidences of in-hospital mortality and procedure-related complications were estimated and compared between groups. Multivariate regression was used to identify independent risk factors for morbidity and mortality. Results:Despite younger average age and lower comorbidity burden, procedure-related complications and in-hospital mortality were more frequent after BTKA than after unilateral procedures (9.45% vs. 7.07% and 0.30% vs. 0.14%; P < 0.0001 each). An increased rate of complications was associated with a staged versus simultaneous approach with no difference in mortality (10.30% vs. 9.15%; P < 0.0001 and 0.29% vs. 0.26%; P = 0.2875). Independent predictors for in-hospital mortality included BTKA (simultaneous: odds ratio, 2.23 [95% confidence interval, 1.69–2.95]; P < 0.0001; staged: odds ratio, 2.01 [confidence interval, 1.28–3.41]; P = 0.0031), male sex (odds ratio, 2.02 [confidence interval, 1.75–2.34]; P < 0.0001), age older than 75 yr (odds ratio, 3.96 [confidence interval, 2.77–5.66]; P < 0.0001), and the presence of a number of comorbidities and complications. Conclusion:BTKAs carry increased risk of perioperative morbidity and mortality compared with unilateral procedures. Staging BTKA procedures during the same hospitalization offers no mortality benefit and may even expose patients to increased morbidity.

Preoperative planning for primary total hip arthroplasty.

Abstract Preoperative planning is of paramount importance in obtaining reproducible results in modern hip arthroplasty. Planning helps the surgeon visualize the operation after careful review of the clinical and radiographic findings. A standardized radiograph with a known magnification should be used for templating. The cup template should be placed relative to the ilioischial line, the teardrop, and the superolateral acetabular margin, so that the removal of the supportive subchondral bone is minimal and the center of rotation of the hip is restored. When acetabular abnormalities are encountered, additional measures are necessary to optimize cup coverage and minimize the risk of malposition. Templating the femoral side for cemented and cementless implants should aim to optimize limb length and femoral offset, thereby improving the biomechanics of the hip joint. Meticulous preoperative planning allows the surgeon to perform the procedure expediently and precisely, anticipate potential intraoperative complications, and achieve reproducible results.

Trends in in-hospital major morbidity and mortality after total joint arthroplasty: United States 1998-2008.

BACKGROUND:The use of total joint arthroplasties is increasing worldwide. In this work we aim to elucidate recent trends in demographics and perioperative outcomes of patients undergoing total hip (THA) or total knee arthroplasty (TKA). METHODS:Data from the US Nationwide Impatient Sample between 1998 and 2008 were gathered for primary THAs and TKAs. Trends in patient age, comorbidity burden, length of hospitalization, frequency of major perioperative complications, and in-hospital mortality were analyzed. In-hospital outcomes were reported as events per 1000 inpatient days to account for changes in length of hospitalization over time. Deyo index, discharge status, and the interaction effect of time and discharge status were included in the adjusted trend analysis for morbidity. RESULTS:Between 1998 and 2008, the average age of patients undergoing TKA and THA decreased by 2 to 3 years (P < 0.001). The average length of stay decreased by approximately 1 day over the time interval studied (P < 0.001). The percentage of patients being discharged home declined from 29.7% to 25.4% after TKA and from 29.3% to 24.2% after THA, in favor of dispositions to long- and short-term care facilities (P < 0.0001). Comorbidity burden as measured by the Deyo comorbidity index increased by 35% and 30% for TKA and THA patients, respectively (P < 0.0001). After TKA, there was an increase in the incidence of the following major complications: pulmonary embolism (coefficient estimate [CE] 0.069; 95% confidence interval [CI], 0.059–0.079; P < 0.0001), sepsis (CE 0.034; 95% CI, 0.014–0.054; P = 0.001), nonmyocardial infarction cardiac complications (CE 0.038; 95% CI, 0.035–0.041; P < 0.0001), and pneumonia (CE 0.039; 95% CI, 0.031–0.047; P < 0.0001). After THA, there was an increase in the incidence of the following major complications: pulmonary embolism (CE 0.031; 95% CI, 0.012–0.049; P = 0.001), sepsis (CE 0.060; 95% CI, 0.039–0.081; P < 0.0001), nonmyocardial infarction cardiac complications (CE 0.040; 95% CI, 0.036–0.043; P < 0.0001), and pneumonia (CE 0.039; 95% CI, 0.029–0.048). In-hospital mortality declined after both TKA (CE −0.059; 95% CI, −0.077 to −0.040; P < 0.0001) and THA (CE −0.068; 95% CI, −0.086 to −0.051; P < 0.0001). CONCLUSION:Between 1998 and 2008, trends show increases in several major in-hospital complications after THA and TKA, including pulmonary embolism, sepsis, nonmyocardial infarction cardiac complications, and pneumonia. Despite the increase in complications, declining in-hospital mortality was noted over this period.

Trends in Demographics, Comorbidity Profiles, In-Hospital Complications and Mortality Associated With Primary Knee Arthroplasty

We analyzed the National Hospital Discharge Survey to elucidate temporal changes in the demographics, comorbidities, hospital stay, in-hospital complications, and mortality of patients undergoing primary total knee arthroplasties (TKAs) in the United States. Three 5-year periods were created (1990-1994, 1995-1999, and 2000-2004), and temporal changes were analyzed. The number of TKAs performed increased by 125% for the 3 periods. The increasing proportion of younger patients was accompanied by a concomitant decrease of Medicare-insured patients. Length of stay decreased from 8.44 to 4.18 days. An increase in the proportion of discharges to long-term and short-term care facilities and in procedures performed in small hospitals was noted. Although the prevalence of procedure-related complications decreased over time, comorbidities increased. Despite a decrease in mortality from the first to the second study period (0.50% vs 0.21%), a slight increase was noticed more recently (0.28%). We identified significant changes in most variables studied.

Clinical and Radiographic Results Associated with a Modern, Cementless Modular Cup Design in Total Hip Arthroplasty

BACKGROUND First-generation cementless modular cups reproducibly achieved fixation to bone but were associated with unacceptable rates of pelvic osteolysis and mechanical failure. Consequently, second-generation cups were developed with shells that had a limited number of holes (or no holes) as well as improved locking mechanisms, a polished inner surface, and increased conformity with the liner. The purpose of the present study was to evaluate the clinical and radiographic results associated with the use of a second-generation acetabular component for primary total hip arthroplasty. METHODS Two hundred and ninety-seven patients underwent 335 consecutive primary total hip arthroplasties that were performed by a single surgeon with a second-generation modular acetabular component. All cups were implanted with a press-fit technique. Ten patients were lost to follow-up, and sixteen died from unrelated causes. The remaining 271 patients (308 hips) were followed clinically (with the Hospital for Special Surgery hip-scoring system) and radiographically for four to seven years. RESULTS One cup was revised because of aseptic loosening. There were seven additional revisions: five were performed because of aseptic loosening of the stem with a well-fixed cup, and two were performed because of deep infection. Among the 271 patients who were alive at the time of the last follow-up, 266 (98%) had retention of the cup and 264 (97%) had retention of both components with a good or excellent clinical result. In the group of 229 patients (262 hips) with complete radiographic follow-up, 259 cups were well fixed and the average wear rate (for the 246 hips for which this rate could be calculated) was 0.09 mm/yr. Osteolysis was detected in twelve hips (5%) and was associated with male gender (p = 0.001) and the annual wear rate (p = 0.004). The extent of calcar resorption was also associated with the annual wear rate (p < 0.001). CONCLUSIONS This second-generation acetabular cup design predictably achieved bone fixation and was associated with low rates of revision for loosening and osteolysis after intermediate-term follow-up.

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

Data of hospitalizations for THA or TKA were analyzed for each year between 1998 and 2007 from the National Inpatient Sample. Demographics, comorbidities, incidence of morbidity and mortality, length of hospital stay (LOS), and overall cost were compared for infected and non-infected patients. Perioperative SSI rates were 0.36% for THA and 0.31% for TKA (412,356 and 784,335 patient entries, respectively). Patients with SSI had a significantly higher overall comorbidity burden, higher perioperative mortality rates, longer length of stay, and higher complication rates. Average cost of in-hospital care was double for SSI versus non-SSI patients. Independent risk factors for perioperative SSI included male gender, minority race, a diagnosis for cancer, liver disease, coagulopathies, fluid and electrolyte disorders, congestive heart failure, and pulmonary circulatory disease. Data relied on coded information and could not differentiate between superficial or deep infection, or capture patients readmitted for SSI, and therefore may have underestimated the true incidence of SSI.

CT Outperforms Radiography for Determination of Acetabular Cup Version after THA

Precise evaluation of acetabular cup version is necessary for patients with recurrent hip dislocation after THA. We retrospectively studied 42 patients, who underwent THAs, with multiple cross-table lateral radiographs and CT scans to determine whether radiographic or CT measurement of acetabular component version is more accurate. One observer measured cup version on all radiographs. CT scans were interpreted by one observer. Twenty radiographs were measured twice each by two observers to determine intraobserver and interobserver reliability. We implanted cups in four model pelvises using navigation and compared measurements of anteversion made with radiographs and CT scans. Intraclass correlation coefficients (ICC) for anteversion measurements of two observers were 0.9990 and 0.9998, respectively, when comparing measurements of identical radiographs (intraobserver). Paired values for two observers measuring the same radiograph had an ICC of 0.9686 (interobserver) compared with 0.7412 for measurements from serial radiographs of the same component. The ICC comparing radiographic versus CT-based measurements was 0.6981. CT measurements had stronger correlations with navigated values than radiographic measurements. Accuracy of anteversion measurements on cross-table radiographs depends on radiographic technique and patient positioning whereas properly performed CT measurements are independent of patient position.Level of Evidence: Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Effective bactericidal activity of tobramycin and vancomycin eluted from acrylic bone cement

We studied the bioactivity of vancomycin and tobramycin eluted from methylmethacrylate bone cement. Aliquots of the drainage were obtained at 1, 6, 12 and 24 hours following total hip prosthetic implantation with vancomycin-tobramycin-loaded cement in 3 patients. The samples were analyzed with fluorescence polarization immunoassay and bioassay, using group B streptococcus for vancomycin and Escherichia coli for tobramycin. These bacteria were selected due to the effectiveness of vancomycin and poor effectiveness of tobramycin against group B streptococcus and conversely with E. coli. The immunodetection of vancomycin averaged 14 (1 hour), 9 (6 hours), 10 (12 hours) and 11 _6;g/mL (24 hours). The bioassay averaged 47, 36, 79 and 41 _6;g/mL (p = 0.03). The immunodetection of tobramycin averaged 43, 21, 18 and 14 _6;g/mL; and bioassay 30, 15, 15 and 12 _6;g/mL (p = 0.1). Both antibiotics eluted with a highly effective bactericidal activity. Our findings indicate that the presence of tobramycin has a synergistic-like effect on the bactericidal activity of vancomycin, which has not been previously reported. We recommend a combination of vancomycin and tobramycin with cement for the treatment of orthopedic infections caused by gram-positive organisms.

Risk factors for perioperative mortality after lower extremity arthroplasty: a population-based study of 6,901,324 patient discharges.

The goal of this study was to provide nationally representative data on characteristics of patients who died after hip and knee arthroplasty and to determine risk factors for such outcome. Using national in-patient data collected between 1990 and 2004, we identified a cumulative in-hospital mortality rate of 0.35% among an estimated 6,901,324 procedures. The strongest independent risk factors for in-hospital mortality were pulmonary embolism and cerebrovascular complications, which increased the odds for a fatal outcome by approximately 40-fold. Preoperative risk factors for in-hospital mortality were revision total hip arthroplasty, advanced age, and the presence of a number of comorbid diseases, predominantly dementia, renal, and cerebrovascular disease. Our results can be used to identify patients at risk for fatal outcome and implement interventions to reduce such risk.

Risk factors for pulmonary embolism after hip and knee arthroplasty: a population-based study

Pulmonary embolism (PE) is a cause of death after total hip and knee arthroplasty (THA, TKA). We characterised the patient population suffering from in-hospital PE and identified perioperative risk factors associated with PE using nationally representative data. Data from the National Hospital Discharge Survey between 1990 and 2004 on patients who underwent primary or revision THA/TKA in the United States were analysed. Multivariate regression analysis was performed to determine if perioperative factors were associated with increased risk of in-hospital PE. An estimated 6,901,324 procedures were identified. The incidence of in-hospital PE was 0.36%. Factors associated with an increased risk for the diagnosis of PE included: revision THA, female gender, dementia, obesity, renal and cerebrovascular disease. An increased association with PE was found among patients with diagnosis of Adult Respiratory Distress Syndrome (ARDS), psychosis (confusion), and peripheral thrombotic events. Our findings may be useful in stratifying the individual patient’s risk of PE after surgery.RésuméL’embolie pulmonaire (PE) est une cause de décès après prothèse totale de hanche ou du genou (THA, TKA). Nous avons essayé de déterminer quelle population pouvait présenter une telle complication et identifier les facteurs de risques pré-opératoires. Pour cela, nous avons analysé nos données hospitalières nationales entre 1990 et 2004 sur tous les patients ayant bénéficié d’une prothèse de hanche ou du genou primaire ou de révision aux Etats-Unis. Une analyse statistique a été réalisée afin de déterminer quels sont les facteurs de risque péri-opératoires associés. 6 901 324 procédures ont été identifiées. Le pourcentage d’embolie pulmonaire durant l’hospitalisation a été de 0,36%. Les facteurs associés sont la révision prothétique, le sexe féminin, la démence, l’obésité, les problèmes rénaux et les problèmes cérébraux vasculaires. Le taux le plus élevé d’embolie pulmonaire a été également trouvé chez les patients ayant un diagnostic d’ARDS et de troubles confusionnels ainsi que d’évènements thrombotiques périphériques. Ces données peuvent être utiles pour évaluer le risque d’embolie pulmonaire chez les patients après chirurgie arthroplastique.