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2.  Patient, Surgery, and Hospital Related Risk Factors for Surgical Site Infections following Total Hip Arthroplasty 
The Scientific World Journal  2015;2015:979560.
Surgical site infections (SSI) following total hip arthroplasty (THA) have a significantly adverse impact on patient outcomes and pose a great challenge to the treating surgeon. Therefore, timely recognition of those patients at risk for this complication is very important, as it allows for adopting measures to reduce this risk. This review discusses literature reported risk factors for SSI after THA. These can be classified into patient-related factors (age, gender, obesity, comorbidities, history of infection, primary diagnosis, and socioeconomic profile), surgery-related factors (allogeneic blood transfusion, DVT prophylaxis and coagulopathy, duration of surgery, antibiotic prophylaxis, bearing surface and fixation, bilateral procedures, NNIS index score, and anesthesia type), and hospital-related factors (duration of hospitalization, institution and surgeon volume, and admission from a healthcare facility). All these factors are discussed with respect to potential measures that can be taken to reduce their effect and consequently the overall risk for infection.
PMCID: PMC4446513  PMID: 26075298
3.  Does Limb Preconditioning Reduce Pain After Total Knee Arthroplasty? A Randomized, Double-blind Study 
Total knee arthroplasty (TKA) can be associated with considerable postoperative pain. Ischemic preconditioning of tissue before inducing procedure-related underperfusion may reduce the postoperative inflammatory response, which further may reduce associated pain.
In this prospective, randomized study, we aimed at evaluating the impact of ischemic preconditioning on postoperative pain at rest and during exercise; use of pain medication; levels of systemic prothrombotic and local inflammatory markers; and length of stay and achievement of physical therapy milestones.
Sixty patients undergoing unilateral TKA under tourniquet were enrolled with half (N = 30) being randomized to an episode of limb preconditioning before induction of ischemia for surgery (tourniquet inflation). Pain scores, analgesic consumption, markers of inflammation (interleukin-6 [IL-6], tumor necrosis factor [TNF]-α in periarticular drainage), and periarticular circumference were measured at baseline and during 2 days postoperatively. Changes in prothrombotic markers were evaluated.
Patients in the preconditioning group had significantly less pain postoperatively at rest (mean difference = −0.71, 95% confidence interval [CI] = −1.40 to −0.02, p = 0.043) and with exercise (mean difference = −1.38, 95% CI = −2.32 to −0.44, p = 0.004), but showed no differences in analgesic consumption. No differences were seen between the study and the control group in terms of muscle oxygenation and intraarticular levels of IL-6 and TNF-α as well as levels of prothrombotic markers. No differences were found between groups in regard to hospitalization length and time to various physical therapy milestones.
Ischemic preconditioning reduces postoperative pain after TKA, but the treatment effect size we observed with the preconditioning routine used was modest.
Clinical Relevance
Given the ease of this intervention, ischemic preconditioning may be considered as part of a multimodal analgesic strategy. However, more study into the impact of different preconditioning strategies, elucidation of mechanisms, safety profiles, and cost-effectiveness of this maneuver is needed.
PMCID: PMC3971250  PMID: 23761178
4.  Perioperative Morbidity and Mortality of Same-day Bilateral TKAs: Incidence and Risk Factors 
Controversy persists regarding the safety of same-day bilateral TKAs, and indications for same-day versus staged bilateral surgery need to be clarified.
We compared the (1) 30-day mortality, (2) rates of in-hospital complications, (3) in-hospital charges, and (4) risk factors for complications among patients undergoing same-day and staged bilateral TKAs at two separate admissions within 1 year either less than 3 months apart (staged 0–3) or more than 3 months apart (staged 3–12) at an institution where same-day bilateral TKAs were discouraged in patients with more severe medical comorbidities.
We analyzed institutional data from 3960 same-day, 172 staged 0–3, and 1533 staged 3–12 bilateral TKAs performed between 1998 and 2011. Patient demographics, comorbidities, and 30-day mortality were tabulated. Same-day patients were younger and healthier. Outcomes of interest included complications, blood transfusions, transfer to rehabilitation, and in-hospital charges. Regression models were conducted to identify independent risk factors for major morbidity or mortality.
There were no differences in 30-day mortality among groups. The same-day group experienced more acute postoperative anemia, blood transfusions, and transfers to rehabilitation, but otherwise had complications comparable to those of the staged groups. In-hospital charges were lower in the same-day group. Congestive heart failure and pulmonary hypertension were the most significant factors associated with morbidity and mortality in the same-day group.
In a high-volume subspecialty setting in which patients undergoing same-day bilateral TKAs were generally much healthier and younger, we found that same-day bilateral TKAs appeared to be safe.
Level of Evidence
Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.
Electronic supplementary material
The online version of this article (doi:10.1007/s11999-013-3156-7) contains supplementary material, which is available to authorized users.
PMCID: PMC3889452  PMID: 23836245
5.  Highly Cross-Linked Polyethylene May Not Have an Advantage in Total Knee Arthroplasty 
HSS Journal  2013;9(3):264-269.
Long-term results after total knee replacement (TKR) with conventional and compression-molded polyethylene (PE) have been excellent. The introduction of highly cross-linked polyethylene (XLPE), which has demonstrated superior wear properties in total hip replacement (THR), has led to its recent use in TKR. However, the knee has a unique biomechanical environment characterized by large contact stresses and shear forces and differs from the highly conforming articulation (and primarily abrasive and adhesive wear) found in THR. For this reason, XLPE, with its decreased fatigue resistance and toughness compared to PE, may not be the best material to withstand these unique forces.
This review and evaluation of the literature aims to answer the following questions. What are the advantages and disadvantages of XLPE in TKR? Does its success in THR ensure a favorable outcome in TKR? Does the increased cost of XLPE justify its use in TKR?
A systematic literature review of MEDLINE, Science Direct, and Google Scholar databases was performed searching for advantages and disadvantages of XLPE in TKR. We found 18 biomechanical in vitro investigations and 3 clinical studies comparing conventional and XLPEs. We included levels I through IV published articles in peer-reviewed journals in English language.
Several in vitro studies found XLPE to have significantly better wear properties compared to conventional PE. However, the two clinical investigations that directly compared conventional PE and XLPE found no difference in clinical or radiographic outcomes. Additionally, clinical studies with long-term follow-up on TKR with conventional PE did not find wear-induced osteolysis to be a major cause of failure. Four studies did find cost to be significantly higher for XLPE compared to conventional PE.
Based on our review, we concluded that (1) the material properties of XLPE reduce adhesive and abrasive wear, but not the risk of crack propagation, deformation, pitting, and delamination found in TKR; (2) wear-induced osteolysis in TKR has not been found to be a major cause of failure at long-term follow-up; (3) mid-term follow-up studies show no difference in any recorded outcome measure between conventional PE and XLPE; and (4) XLPE is two to four times the cost of conventional PE without an improvement in clinical or radiographic outcomes. For these reasons, we currently cannot recommend the use of XLPE in TKR. Conventional compression-molded polyethylene with its outstanding long-term results should remain the material of choice in TKR.
Electronic supplementary material
The online version of this article (doi:10.1007/s11420-013-9352-x) contains supplementary material, which is available to authorized users.
PMCID: PMC3772158  PMID: 24426878
cross-linked; polyethylene; total knee replacement; annealed; remelted; radiation; crack; compression molded
6.  Novel CT-based Three-dimensional Software Improves the Characterization of Cam Morphology 
Incomplete correction of femoral offset and sphericity remains the leading cause for revision surgery for symptomatic femoroacetabular impingement (FAI). Because arthroscopic exploration is technically difficult, a detailed preoperative understanding of morphology is of paramount importance for preoperative decision-making.
The purposes of this study were to (1) characterize the size and location of peak cam deformity with a prototype CT-based software program; (2) compare software alpha angles with those obtained by plain radiograph and CT images; and (3) assess whether differences can be explained by variable measurement locations.
We retrospectively reviewed the preoperative plain radiographs and CT scans of 100 symptomatic cam lesions treated by arthroscopy; recorded alpha angle and clockface measurement location with a novel prototype CT-based software program, CT, and Dunn lateral plain radiographs; and used ordinary least squares regressions to assess the relationship between alpha angle and measurement location.
The software determined a mean alpha angle of 70.8° at 1:23 o’clock and identified 60% of maximum alpha angles between 12:45 and 1:45. The CT and plain radiographs underestimated by 5.7° and 8.2°, respectively. The software-based location was anterosuperior to the mean CT and plain radiograph measurement locations by 41 and 97 minutes, respectively. Regression analysis confirmed a correlation between alpha angle differences and variable measurement locations.
Software-based three-dimensional (3-D) imaging generated alpha angles larger than those found by plain radiograph and CT, and these differences were the result of location of measurement. An automated 3-D assessment that accurately describes the location and topography of FAI may be needed to adequately characterize preoperative deformity.
Level of Evidence
Level III, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3705074  PMID: 23361933
7.  Anterior Inferior Iliac Spine Morphology Correlates With Hip Range of Motion: A Classification System and Dynamic Model 
The anterior inferior iliac spine (AIIS) contributes to hip dysfunction in patients with symptomatic impingement and resection of a prominent AIIS can reportedly improve function. However, the variability of the AIIS morphology and whether that variability correlates with risk of associated symptomatic impingement are unclear.
We characterized AIIS morphology in patients with hip impingement and tested the association between specific AIIS variants and hip range of motion.
We evaluated three-dimensional CT reconstructions of 53 hips (53 patients) with impingement and defined three morphological AIIS variants: Type I when there was a smooth ilium wall between the AIIS and the acetabular rim, Type II when the AIIS extended to the level of the rim, and Type III when the AIIS extended distally to the acetabular rim. A separate cohort of 78 hips (78 patients) with impingement was used to compare hip range of motion among the three AIIS types.
Mean hip flexion was limited to 120°, 107°, and 93° in hips with Type I, Type II, and Type III AIIS, respectively. Mean internal rotation was limited to 21°, 11°, and 8° in hips with Type I, Type II, and Type III AIIS, respectively.
When the AIIS is classified into three variants based on the relationship between the AIIS and the acetabular rim in patients with impingement, Type II and III variants are associated with a decrease in hip flexion and internal rotation, supporting the rationale for considering AIIS decompression for variants that extend to and below the rim.
Level of Evidence
Level III, diagnostic study. See Guidelines for Authors for a complete description of levels of evidence.
PMCID: PMC3705064  PMID: 23412732
8.  Blood Transfusions in Total Hip and Knee Arthroplasty: An Analysis of Outcomes 
The Scientific World Journal  2014;2014:623460.
Background. Various studies have raised concern of worse outcomes in patients receiving blood transfusions perioperatively compared to those who do not. In this study we attempted to determine the proportion of perioperative complications in the orthopedic population attributable to the use of a blood transfusion. Methods. Data from 400 hospitals in the United States were used to identify patients undergoing total hip or knee arthroplasty (THA and TKA) from 2006 to 2010. Patient and health care demographics, as well as comorbidities and perioperative outcomes were compared. Multivariable logistic regression models were fitted to determine associations between transfusion, age, and comorbidities and various perioperative outcomes. Population attributable fraction (PAF) was determined to measure the proportion of outcome attributable to transfusion and other risk factors. Results. Of 530,089 patients, 18.93% received a blood transfusion during their hospitalization. Patients requiring blood transfusion were significantly older and showed a higher comorbidity burden. In addition, these patients had significantly higher rates of major complications and a longer length of hospitalization. The logistic regression models showed that transfused patients were more likely to have adverse health outcomes than nontransfused patients. However, patients who were older or had preexisting diseases carried a higher risk than use of a transfusion for these outcomes. The need for a blood transfusion explained 9.51% (95% CI 9.12–9.90) of all major complications. Conclusions. Advanced age and high comorbidity may be responsible for a higher proportion of adverse outcomes in THA and TKA patients than blood transfusions.
PMCID: PMC3918859  PMID: 24587736
9.  Epidemiology and risk factors for perioperative mortality after total hip and knee arthroplasty 
The perioperative mortality of total knee and hip arthroplasties (TKA, THA) remains a major concern among health care providers and their patients. The increase in utilization of TKA and THA makes it imperative to be aware of factors that are associated with this unfortunate event.
Therefore we analyzed the Nationwide Inpatient Sample data from 1998–2008 and compared admissions with perioperative mortality to those that survived their hospitalization.
An estimated total of 4,438,213 TKA and 2,182,121 THA procedures were performed in the United States between 1998 and 2008. The average mortality rate for TKA was 0.13% and 0.18% for THA, or 0.34 and 0.44 events per 1000 inpatient days, respectively. Independent risk factors for in-hospital mortality were advanced age, male gender, ethnic minority background, emergency admission as well as a number of comorbidities and complications. Furthermore, we demonstrated that the timing of death occurred earlier after TKA when compared to THA, with 50% of fatalities occurring by day 4 versus day 6 of the hospitalization, respectively.
This study provides nationally representative information on risk factors for and timing of perioperative mortality after TKA and THA. Our data can be used to assess the risk for perioperative mortality and to develop targeted intervention to decrease such risk.
PMCID: PMC3407319  PMID: 22517400
total knee arthroplasty; total hip arthroplasty; joint replacement; complications; mortality
10.  Predictors for moderate to severe acute postoperative pain after total hip and knee replacement 
International Orthopaedics  2012;36(11):2261-2267.
The ability to identify and focus care to patients at higher risk of moderate to severe postoperative pain should improve analgesia and patient satisfaction, and may affect reimbursement. We undertook this multi-centre cross-sectional study to identify preoperative risk factors for moderate to severe pain after total hip (THR) and knee (TKR) replacement.
A total of 897 patients were identified from electronic medical records. Preoperative information and anaesthetic technique was gained by retrospective chart review. The primary outcomes were moderate to severe pain (pain score ≥ 4/10) at rest and with activity on postoperative day one. Logistic regression was performed to identify predictors for moderate to severe pain.
Moderate to severe pain was reported by 20 % at rest and 33 % with activity. Predictors for pain at rest were female gender (OR 1.10 with 95 % CI 1.01–1.20), younger age (0.96, 0.94–0.99), increased BMI (1.02, 1.01–1.03), TKR vs. THR (3.21, 2.73–3.78), increased severity of preoperative pain at the surgical site (1.15, 1.03–1.30), preoperative use of opioids (1.63, 1.32–2.01), and general anaesthesia (8.51, 2.13–33.98). Predictors for pain with activity were TKR vs. THR (1.42, 1.28–1.57), increased severity of preoperative pain at the surgical site (1.11, 1.04–1.19), general anaesthesia (9.02, 3.68–22.07), preoperative use of anti-convulsants (1.78, 1.32–2.40) and anti-depressants (1.50, 1.08–2.80), and prior surgery at the surgical site (1.28, 1.05–1.57).
Our findings provide clinical guidance for preoperative stratification of patients for more intensive management potentially including education, nursing staffing, and referral to specialised pain management.
PMCID: PMC3479283  PMID: 22842653
11.  An Algorithmic Approach to Mechanical Hip Pain 
HSS Journal  2012;8(3):213-224.
As our understanding of hip pathology evolves, the focus is shifting toward earlier identification of hip pathology. Therefore, it is vitally important to elucidate intra-articular versus extra-articular pathology of hip pain in every step of the patient encounter: history, physical examination, and imaging.
The objective was to address the following research questions: (1) Can an algorithmic approach to physical examination of a painful non-arthritic hip provide a more accurate diagnosis and improved treatment plan? (2) Does an anatomical layered concept of clinical diagnosis improve diagnostic accuracy? (3) What are the diagnostic tools necessary for the accurate application of a four-layer (osteochondral, inert, contractile, and neuromechanical) diagnosis?
An unrestricted computerized search of MEDLINE was conducted. Different terms were used in various combinations.
An algorithmic approach to physical examination of a painful nonarthritic hip, including history, physical examination (specific tests), and advanced imaging allow for better interpretation of debilitating intra- and extra-articular disorders and their effect on core performance. Additionally, it improves our understanding as to how underlying abnormal joint mechanics may predispose the hip joint and the associated hemipelvis to asymmetric loads. These abnormal joint kinematics (layer I) can lead to cartilage and labral injury (layer II), as well as resultant injury to the musculotendinous (layer III) and neural structures (layer IV) about the hip joint and the hemipelvis. The layer concept is a systematic means of determining which structures about the hip are the source of hip pathology and how to best implement treatment.
A clear understanding of the differential diagnosis of hip pain through a detailed and systematic physical examination, diagnostic imaging assessment, and the interpretation of how mechanical factors can result in such a wide range of compensatory injury patterns about the hip can facilitate the diagnosis and treatment recommendations.
PMCID: PMC3470663  PMID: 24082863
hip pain; mechanical hip pain; intra-articular hip pathology; extra-articular hip pathology; physical examination of the hip joint
12.  Comparative Perioperative Outcomes Associated With Neuraxial Versus General Anesthesia for Simultaneous Bilateral Total Knee Arthroplasty 
Background and Objectives
The influence of the type of anesthesia on perioperative outcomes after bilateral total knee arthroplasty (BTKA) remains unknown. Therefore, we examined a large sample of BTKA recipients, hypothesizing that neuraxial anesthesia would favorably impact on outcomes.
We identified patient entries indicating elective BTKA between 2006 and 2010 in a national database; subgrouped them by type of anesthesia: general (G), neuraxial (N), or combined neuraxial-general (NG); and analyzed differences in demographics and perioperative outcomes.
Of 15,687 identified procedures, 6.8% (n = 1066) were performed under N, 80.1% (n = 12,567) under G, and 13.1% (n = 2054) under NG. Comparing N to G and NG, patients in group N were, on average, younger (63.9, 64.6, and 64.8 years; P = 0.030) but did not differ in overall comorbidity burden. Patients in group N required blood product transfusions significantly less frequently (28.5%, 44.7%, 38.0%; P < 0.0001). In-hospital mortality, 30-day mortality, and complication rates tended to be lower in group N, without reaching statistical significance. After adjusting for covariates, N and NG were associated with 16.0% and 6.0% reduction in major complications compared with G, but only the reduced odds for the requirement of blood transfusions associated with N reached statistical significance (N vs G: odds ratio, 0.52 [95% CI, 0.45–0.61], P < 0.0001; NG vs G: odds ratio, 0.77 [95% CI, 0.69–0.86], P < 0.0001).
Neuraxial anesthesia for BTKA is associated with significantly lower rates of blood transfusions and, by trend, decreased morbidity. Although by itself the effect may be limited, N might be used within a multimodal approach to reduce complications after BTKA.
PMCID: PMC3653590  PMID: 23080348
13.  Bilateral Total Knee Arthroplasty: Risk Factors for Major Morbidity and Mortality 
Anesthesia and analgesia  2011;113(4):784-790.
Bilateral total knee arthroplasties (BTKA) performed during the same hospitalization carry increased risk for morbidity and mortality as compared to the unilateral approach. However, no evidence-based stratifications to identify patients at risk for major morbidity and mortality are available. Our objective was to determine the incidence and patient-related risk factors for major morbidity and mortality among patients undergoing BTKA.
Nationwide Inpatient Survey data collected for the years 1998–2007 were analyzed and cases of elective BTKA procedures were included. Patient demographics, including comorbidities, were analyzed and frequencies of mortality and major complications were computed. Subsequently, a multivariate analysis was conducted to determine independent risk factors for major morbidity and mortality.
Included were 42,003 database entries, representing an estimated 206,573 elective BTKA. The incidence of major in-hospital complications and mortality was 9.5%. Risk factors for adverse outcome included advanced age [odds ratios (OR) for age groups 65–74 and >75 years were 1.88 (Confidence Interval (CI) 1.72; 2.05) and 2.66 (CI 2.42; 2.92), respectively, compared to the 45–65 year group], male gender [OR 1.54 (CI 1.44; 1.66)], and a number of comorbidities. The presence of congestive heart failure (OR 5.55 (CI 4.81; 6.39)) and pulmonary hypertension [OR 4.10 (CI2.72; 6.10)] were the most significant risk factors associated with increased odds for adverse outcome.
We identified patient-related risk factors for major morbidity and mortality in patients undergoing BTKA. Our data can be used to aid in the selection of patients for this procedure.
PMCID: PMC3183335  PMID: 21752942
14.  Central Role of SREBP-2 in the Pathogenesis of Osteoarthritis 
PLoS ONE  2012;7(5):e35753.
Recent studies have implied that osteoarthritis (OA) is a metabolic disease linked to deregulation of genes involved in lipid metabolism and cholesterol efflux. Sterol Regulatory Element Binding Proteins (SREBPs) are transcription factors regulating lipid metabolism with so far no association with OA. Our aim was to test the hypothesis that SREBP-2, a gene that plays a key role in cholesterol homeostasis, is crucially involved in OA pathogenesis and to identify possible mechanisms of action.
Methodology/Principal Findings
We performed a genetic association analysis using a cohort of 1,410 Greek OA patients and healthy controls and found significant association between single nucleotide polymorphism (SNP) 1784G>C in SREBP-2 gene and OA development. Moreover, the above SNP was functionally active, as normal chondrocytes’ transfection with SREBP-2-G/C plasmid resulted in interleukin-1β and metalloproteinase-13 (MMP-13) upregulation. We also evaluated SREBP-2, its target gene 3-hydroxy-3-methylglutaryl-coenzymeA reductase (HMGCR), phospho-phosphoinositide3-kinase (PI3K), phospho-Akt, integrin-alphaV (ITGAV) and transforming growth factor-β (TGF-β) mRNA and protein expression levels in osteoarthritic and normal chondrocytes and found that they were all significantly elevated in OA chondrocytes. To test whether TGF-β alone can induce SREBP-2, we treated normal chondrocytes with TGF-β and found significant upregulation of SREBP-2, HMGCR, phospho-PI3K and MMP-13. We also showed that TGF-β activated aggrecan (ACAN) in chondrocytes only through Smad3, which interacts with SREBP-2. Finally, we examined the effect of an integrin inhibitor, cyclo-RGDFV peptide, on osteoarthritic chondrocytes, and found that it resulted in significant upregulation of ACAN and downregulation of SREBP-2, HMGCR, phospho-PI3K and MMP-13 expression levels.
We demonstrated, for the first time, the association of SREBP-2 with OA pathogenesis and provided evidence on the molecular mechanism involved. We suggest that TGF-β induces SREBP-2 pathway activation through ITGAV and PI3K playing a key role in OA and that integrin blockage may be a potential molecular target for OA treatment.
PMCID: PMC3360703  PMID: 22662110
15.  Influence of Interleukin 1α (IL-1α), IL-4, and IL-6 Polymorphisms on Genetic Susceptibility to Chronic Osteomyelitis▿  
Clinical and Vaccine Immunology : CVI  2008;15(12):1888-1890.
The association between cytokine gene polymorphisms and chronic osteomyelitis was investigated in order to determine whether genetic variability in cytokine genes predisposes to osteomyelitis susceptibility. Significant genotypic and allelic associations were observed between interleukin 1α (IL-1α) −889-C/T, IL-4 −1098-G/T and −590-C/T, and IL-6 −174-G/C polymorphisms and osteomyelitis in the Greek population, pointing towards their potential involvement in osteomyelitis pathogenesis.
PMCID: PMC2593176  PMID: 18971305
16.  Epidural bleeding after ACL reconstruction under regional anaesthesia: a case report 
Cases Journal  2009;2:6732.
Epidural bleeding as a complication of catheterization or epidural catheter removal is often associated with perioperative thromboprophylaxis especially in adult reconstructive surgery.
Case presentation
We report on a case of a 19 years old male athlete that underwent anterior cruciate ligament reconstruction, receiving low molecular weight heparin for thromboprophylaxis and developed an epidural hematoma and subsequent cauda equina syndrome two days after removal of the epidural catheter. An urgent magnetic resonance imaging scan revealed an epidural hematoma from the level of L3 to L4. Emergent decompression and hematoma evacuation resulted in patient's significant neurological improvement immediately postoperatively.
A high index of clinical suspicion and surgical intervention are necessary to prevent such potentially disabling complications especially after procedures on a day-case basis and early patient's discharge.
PMCID: PMC2740288  PMID: 19829853

Results 1-16 (16)