Bilateral Total Knee Arthroplasty and In-Hospital Opioid Dispension: A Population-Based Study.

BACKGROUND: There is paucity of data regarding opioid dispension in patients undergoing bilateral total knee arthroplasty (BTKA). Our aim is to compare in-hospital opioid dispension between BTKA and unilateral TKA (UTKA) and to identify other factors associated with opioid dispension in the BTKA and UTKA cohorts. METHODS: Patients receiving elective TKA from 2006 to 2016 were retrospectively extracted from the Premier Healthcare Database. The effect of interest was bilateral TKA. Our primary outcome was in-hospital opioid dispension in oral morphine equivalents. Univariable statistics between study variables and TKA type were obtained. A multilevel logistic regression model was run for the outcome of high opioid dispension. RESULTS: A total of 1,029,120 patients were included. Among these, 14,469 (1.4%) underwent a BTKA. Within the 10-year period studied, there was a decrease in opioid dispension in both groups. Logistic regression analysis showed that patients treated with BTKA had 1.68 times higher odds for high opioid dispension compared to UTKA patients (odds ratio = 1.68; 95.5% confidence interval = 1.62, 1.75; P < .0001). White race, longer length of stay, Charlson/Deyo index, type of insurance, rural location, general anesthesia, peripheral nerve block use, and patient-controlled analgesia were also associated with high opioid dispension. Conversely, a more recent year of surgery, female gender, older age, and administration of nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors were associated with lower odds for high opioid dispension. CONCLUSION: BTKA patients have increased odds for higher in-hospital opioid dispension compared to UTKA recipients. Utilization and prescribing habits should be examined to determine the optimal approach to opioid prescription in BTKA patients compared to UTKA.

Characterization of laboratory and real driving emissions of individual Euro 6 light-duty vehicles - Fresh particles and secondary aerosol formation.

Emissions from passenger cars are one of major sources that deteriorate urban air quality. This study presents characterization of real-drive emissions from three Euro 6 emission level passenger cars (two gasoline and one diesel) in terms of fresh particles and secondary aerosol formation. The gasoline vehicles were also characterized by chassis dynamometer studies. In the real-drive study, the particle number emissions during regular driving were 1.1-12.7 times greater than observed in the laboratory tests (4.8 times greater on average), which may be caused by more effective nucleation process when diluted by real polluted and humid ambient air. However, the emission factors measured in laboratory were still much higher than the regulatory value of 6 × 1011 particles km-1. The higher emission factors measured here result probably from the fact that the regulatory limit considers only non-volatile particles larger than 23 nm, whereas here, all particles (also volatile) larger than 3 nm were measured. Secondary aerosol formation potential was the highest after a vehicle cold start when most of the secondary mass was organics. After the cold start, the relative contributions of ammonium, sulfate and nitrate increased. Using a novel approach to study secondary aerosol formation under real-drive conditions with the chase method resulted mostly in emission factors below detection limit, which was not in disagreement with the laboratory findings.

Same-Day Surgery Does Not Increase the Manipulation Under Anesthesia and Reoperation Rates for Stiffness Following Bilateral Total Knee Arthroplasty.

BACKGROUND: There is a paucity of data on the incidence of stiffness and need for subsequent manipulation under anesthesia (MUA) and reoperation following same-day bilateral total knee arthroplasty (BTKA). We compared the rates of at least 1 MUA, bilateral knee involvement, single and multiple MUA rates, and stiffness-related reoperation rates between patients undergoing same-day, same-admission staged, and staged within 1 year BTKA in a tertiary institution. METHODS: We analyzed institutional data for 3175 same-day (group A), 153 same-admission staged (group B), and 1226 staged within 1 year BTKA patients (group C) from 1998 to 2009. Several variables, including patient demographics, comorbidity profile, Charlson-Deyo index, and range of motion at different time points, were tabulated. Follow-up was minimum 1 year after first MUA. Univariate analyses were performed using the Wilcoxon rank-sum or Kruskal-Wallis test, and Fisher exact or the chi-square test for continuous and categorical variables, respectively. The Cochran-Armitage trend test was used to check the bilateral knee involvement rate across groups. RESULTS: Overall, 2.2% (98/4554) of BTKA patients required MUA. The rate of at least 1 MUA was similar across groups but the percentage of bilateral knee involvement was higher in group A. The single MUA rate was comparable among groups. Both no revision and revision reoperation rates were similar among the manipulated groups. CONCLUSION: Same-day BTKA was not associated with increased incidence of single or multiple MUA and stiffness-related reoperation rates. These findings may facilitate preoperative counseling in patients with symptomatic bilateral knee disease, eligible for same-day BTKA.

Superior knee flexor strength at 2 years with all-inside short-graft anterior cruciate ligament reconstruction vs a conventional hamstring technique.

PURPOSE: To compare the "all-inside technique" for anterior cruciate ligament (ACL) reconstruction using a short, quadrupled semitendinosus tendon (ST4) autograft and suspensory cortical fixation on both the femoral and tibial side vs the "conventional technique" using a semitendinosus/gracilis (ST/G) autograft fixed with a suspensory device on the femoral side and with an interference screw on the tibial side, in terms of clinical and functional outcomes. METHODS: A total of 90 patients were enrolled, randomised into two groups, and prospectively followed. Group A comprised 45 patients treated with the all-inside technique and Group B included 45 patients treated with the conventional ACL technique (55 males, 35 females; mean age 28.7 ± 11.3 years). Patients completed the Lysholm knee score, the International Knee Documentation Committee (IKDC) score, the Knee Injury and Osteoarthritis Score (KOOS), and the Knee Society Score (KSS) preoperatively and at 2 years postoperatively. Anterior tibial translation measurement (KT-1000 arthrometer) and isokinetic testing of the operative vs non-operative limb were also conducted and the limb symmetry index (LSI) was determined. RESULTS: At 24 months, the Lysholm, IKDC, KOOS, and KSS scores between the two groups were similar (n.s.). Anterior tibial translation between the operative and non-operative knee was also similar among the two groups (n.s.). Patients of Group A had significantly higher mean LSIs in terms of flexor peak torque (1.0 ± 0.1 vs 0.9 ± 0.1; p < 0.001), time-to-peak (0.9 ± 0.1 vs 0.8 ± 0.1; p < 0.001) and total work (0.9 ± 0.1 vs 0.8 ± 0.1; p < 0.001) at 180°/s, and significantly better mean LSI for isometric flexor/extensor ratio at 90° (1.1 ± 0.3 vs 0.8 ± 0.2; p < 0.001). CONCLUSION: The all-inside ACL reconstruction with an ST4 autograft and cortical button fixation on both ends is a viable alternative to the conventional technique. It affords preservation of knee flexor strength, which is of advantage, especially when treating athletes with ACL injury. LEVEL OF EVIDENCE: I.

A study on the CO2 and NOx emissions performance of Euro 6 diesel vehicles under various chassis dynamometer and on-road conditions including latest regulatory provisions.

The current study presents a detailed analysis of the gaseous emissions, focusing on CO2 and NOx, of diesel vehicles under several operating conditions. An assessment is also made on the impact and effectiveness of the Real Driving Emissions (RDE) test, which is mandatory by the European Union (EU) type approval regulation for passenger cars since September 2017. The method followed comprises emissions measurement tests on three Euro 6 diesel vehicles, under laboratory and various on-road operation conditions. Chassis dynamometer tests in the laboratory showed that emissions over the current type approval test (World-wide harmonized Light-duty Test Procedure or WLTP), and over the former one (New European Driving Cycle or NEDC), poorly reflect real-world levels. However, the most demanding CADC testing comes closer to real drive emissions. Comparison of driving conditions on the chassis dynamometer over different driving cycles and on the road reveals that the emission performance substantially varies between different tests, even for apparently similar operation conditions. The NOx emissions reduction strategy of pre-RDE monitoring Euro 6 vehicles seems to be optimized for the NEDC driving conditions, which are not representative of the real-world driving conditions. The real-world emissions during normal driving conditions are effectively captured with the new RDE test, however driving the vehicle dynamically, at conditions outside the RDE regulation boundaries, results to disproportional high emissions. This is a significant shortcoming which might be critical for populations living on hilly areas or those close to specific micro-environments, such as highway entrance ramps, traffic lights, etc.

Surgical approach does not affect deep infection rate after primary total hip arthroplasty.

BACKGROUND: There is a concern for higher rates of wound complications and a potentially increased periprosthetic joint infection (PJI) risk after total hip arthroplasty (THA) with the direct anterior approach (DAA) compared to the posterolateral approach (PLA). Our purpose was to compare PJI risk after THA with the DAA or the PLA and to identify risk factors for PJI after primary THA. METHODS: Clinical characteristics of patients treated in our institution with primary DAA or PLA THA between 1/2010 and 12/2015 were retrospectively reviewed. The respective deep PJI rates were calculated. A logistic regression model was constructed to determine a potential difference in the PJI risk between the 2 groups, and risk factors for hip PJI in all patients. RESULTS: During the period studied, there were 1,182 DAA THAs and 18,853 PLA THAs. The PJI rate was 0.25% for the DAA group and 0.31% for the PLA group (p = 1.0). The DAA was not associated with a significantly increased risk for PJI compared to the PLA. Compared to younger patients, older patients had lower PJI risk; patient discharge to home was also associated with lower PJI risk compared to other discharge disposition; longer length of stay was associated with higher PJI risk compared to shorter length of stay. CONCLUSION: The DAA is equally safe compared the PLA with respect to PJI risk. Younger age, discharge to facilities other than home and increased length of stay increase the risk for deep PJI after primary THA.

Optimizing Intraoperative Blood Management for One-Stage Bilateral Total Knee Arthroplasty.

BACKGROUND: Effective blood management strategies are a major determinant of successful outcomes after one-stage bilateral total knee arthroplasty (BTKA). Proper patient selection with preoperative optimization and intra- and postoperative interventions can reduce transfusion risk and associated morbidity in these patients. QUESTIONS/PURPOSES: The purpose of this study was to evaluate intraoperative blood management modalities based on three keystone questions: (1) What is the role of the anesthesiologist?, (2) Which are the surgeon-dependent strategies?, and (3) Is there any place for pharmacologic interventions? METHODS: We searched the established electronic literature database MEDLINE. After critical appraisal, 94 studies were deemed eligible from which to draw documented evidence. RESULTS: A number of blood-conserving methods are currently implemented in patients undergoing one-stage BTKA. Among them, regional anesthesia, tourniquet use, and tourniquet deflation after wound closure, femoral canal sparing or femoral canal plugging, avoidance of drains, and tranexamic acid use were the intraoperative strategies with documented efficacy in blood conservation. CONCLUSION: Combined proper intraoperative anesthesiologic, surgical, and pharmacologic interventions reduce blood loss and need for transfusion in BTKA patients. However, contemporary relevant literature is lacking evidence-based guidelines.

Does blood transfusion type affect complication and length of stay following same-day bilateral total knee arthroplasty?

Same-day Bilateral Total Knee Arthroplasty (BTKA) safety is still controversial. The aim of this study was to examine the association of blood transfusion type (pure autologous, pure allogeneic, and combined) with complication and prolonged length of stay (PLOS) following same-day BTKA. 649 consecutive patients were retrospectively identified over a two-year period. Pure allogeneic transfusions were associated with increased odds of minor complication when compared to patients who had pure autologous transfusions. No association was found between blood transfusion type and major complication or PLOS. Our results suggest that blood transfusion type may be influential in minor complication after BTKA.

Experimental assessment of the potential to decrease diesel NOx emissions beyond minimum requirements for Euro 6 Real Drive Emissions (RDE) compliance.

The objective of this study was to test the potential for NOx emissions improvements on a typical Euro 6 diesel vehicle, following modifications to its emissions control system, under Real Drive Emissions (RDE) testing conditions. A commercially available car was selected and was first measured in its original configuration according to RDE on the road and an initial conformity factor (CF) of 5.4 was determined. Subsequent engine calibration and installation of a Selective Catalytic Reduction (SCR) device were conducted and tested on a fully transient engine dyno setup, which precisely reproduced the engine operation under the on-road RDE test. The NOx reduction achieved with those upgrades was 90%, leading to a CF of 0.53, with no CO2 or fuel consumption penalty. These findings demonstrate that diesel vehicles can reach low NOx levels under real world driving conditions, when well-designed modern exhaust aftertreatment components are installed and properly calibrated.

Infection risk assessment in patients undergoing primary total knee arthroplasty.

PURPOSE: To determine the incidence and to identify potential risk factors for in-hospital and late infections, as well as for deep periprosthetic joint infection (PJI) following TKA. METHODS: We identified 17,959 patients treated with primary TKA between 2000 and 2009. We recorded patient demographics, comorbidities and in-hospital complications. The rates of in-hospital, late, and deep PJIs were determined. Different logistic regression models were built to identify risk factors for each of the above types of infection. RESULTS: The rates for in-hospital, post-discharge, and deep PJI were 0.65%, 0.41%, and 0.26%, respectively. Younger age, allogeneic blood transfusion, liver disease, and unilateral or staged bilateral TKA were risk factors for in-hospital infection. Renal and pulmonary disease, urinary tract infection, wound dehiscence, and prior in-hospital infection were risk factors for post-discharge infection. Male gender, history of in-hospital infection, prolonged length of stay, and pulmonary disease were identified as risk factors for deep PJI. CONCLUSION: Despite low infection rates after primary TKA, there are patients at higher risk that would benefit by addressing modifiable risk factors for both in-hospital or post-discharge infections, including deep PJIs.

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

BACKGROUND: As periprosthetic joint infections (PJIs) can have tremendous health and socioeconomic implications, recognizing patients at risk before surgery is of great importance. Therefore, we sought to determine the rate of and risk factors for deep PJI in patients undergoing primary total hip arthroplasty (THA). METHODS: Clinical characteristics of patients treated with primary THA between January 1999 and December 2013 were retrospectively reviewed. These included patient demographics, comorbidities (including the Charlson/Deyo comorbidity index), length of stay, primary diagnosis, total/allogeneic transfusion rate, and in-hospital complications, which were grouped into local and systemic (minor and major). We determined the overall deep PJI rate, as well as the rates for early-onset (occurring within 2 years after index surgery) and late-onset PJI (occurring more than 2 years after surgery). A Cox proportional hazards regression model was constructed to identify risk factors for developing deep PJI. Significance level was set at 0.05. RESULTS: A deep PJI developed in 154 of 36,494 primary THAs (0.4%) during the study period. Early onset PJI was found in 122 patients (0.3%), whereas late PJI occurred in 32 patients (0.1%). Obesity, coronary artery disease, and pulmonary hypertension were identified as independent risk factors for deep PJI after primary THA. CONCLUSION: The rate of deep PJIs of the hip is relatively low, with the majority occurring within 2 years after THA. If the optimization of modifiable risk factors before THA can reduce the rate of this complication remains unknown, but should be attempted as part of good practice.

Perioperative Morbidity of Same-Day and Staged Bilateral Total Hip Arthroplasty.

BACKGROUND: Management strategies for bilateral hip degenerative disease include same-day or staged bilateral total hip arthroplasty (THA), but information on outcomes remains sparse. We sought to describe in-hospital complications and blood transfusion rates after same-day and staged bilateral THAs at different time intervals and to assess risk factors for these events. METHODS: We retrospectively reviewed administrative data for 3785 patients treated with same-day bilateral (n = 1946; group A) and staged bilateral THA within (1) 0-3 months apart (n = 328; group B); (2) 3-6 months apart (n = 703; group C); and (3) 6-12 months apart (n = 808; group D), between 1999 and 2014. We recorded demographics, the Charlson-Deyo comorbidity index and in-hospital local and systemic (minor and major) complications. Complication and blood transfusion rates among groups were compared. A logistic regression model was developed to identify risk factors for major complications. RESULTS: Local complications were rare. Minor complications were less frequent in group A (P < .001). Major complications were more frequent in group D (P = .012). Group A had higher overall (P < .001) and allogeneic blood transfusion rates (P < .001) compared with the staged groups. Staged procedures within 6-12 months apart vs same-day bilateral THA, older age, Charlson-Deyo index ≥2 vs 0, and earlier vs recent admission year were associated with higher adjusted odds for major complications. CONCLUSION: Same-day bilateral THA in a high-volume joint replacement center may be a safe option for younger and healthier patients, given the relatively low incidence of adverse events reported in this study.

Periprosthetic Infection Recurrence After 2-Stage Exchange Arthroplasty: Failure or Fate?

BACKGROUND: Two-stage exchange arthroplasty remains the preferred method for treating a chronic periprosthetic joint infection (PJI) in North America. However, infection recurrence may occur. Previously, recurrent infections have been classified as persistent (same isolated pathogen) or new (different pathogen identified). We sought to determine (1) recurrence rates among patients with chronic hip and knee PJI, treated with 2-stage exchange arthroplasty; (2) risk factors for infection recurrence; and (3) risk factors for developing persistent vs new infection. METHODS: We retrospectively reviewed clinical characteristics of patients with chronic hip and knee PJI, treated with 2-stage revision between January 1998 and March 2014. Minimum follow-up was 24 months. Two multivariate logistic regression models were constructed to determine independent predictors for infection recurrence and persistence. RESULTS: In total, 548 patients were identified (283 men, 265 women). Forty-eight had a recurrent infection (8.76%). Men had 54.8% lower odds of PJI recurrence than women (odds ratio [OR] = 0.452; 95% confidence interval [CI], 0.235-0.869). Patients with heart disease had 109% higher odds of infection recurrence than patients without heart disease (OR = 2.09; 95% CI, 1.097-3.081). The risk of infection recurrence was 119% higher in patients with psychiatric disorders than in patients without psychiatric disorders (OR = 2.19; 95% CI, 1.011-4.761). Patients with recurrent knee PJI had 84.6% lower odds of persistent infection (OR = 0.154; 95% CI, 0.034-0.696) compared to hip PJI. Patients with heart disease had 5-fold increased odds for persistent PJI (OR = 5.068; 95% CI, 1.38-22.56). CONCLUSION: Female gender, heart disease, and psychiatric disorders increase the risk of hip and knee PJI recurrence. Patients with PJI of the hip and with heart disease are at higher risk of infection persistence.

Implant retention after acute and hematogenous periprosthetic hip and knee infections: Whom, when and how?

Periprosthetic joint infections (PJI) of the hip and the knee are grossly classified as early post-operative, acute hematogenous and late chronic infections. Whereas two-stage exchange arthroplasty is the standard of care in North America for treating chronic infections, irrigation and debridement (I and D) with retention of implants has been used in an attempt to treat the other two types of PJIs. The rationale of this approach is that a PJI may be eradicated without the need of explanting the prostheses, as long as it has not transitioned into a chronic state. With the present paper, we review current evidence regarding the role of I and D with implant retention for treating PJIs of the hip and the knee. While a very wide range of success rates is reported in different studies, a short period of time between initiation of symptoms and intervention seems to play a prominent role with regards to a successful outcome. Moreover, pathogens of higher virulence and resistance to antibiotics are associated with a poorer result. Specific comorbidities have been also correlated with a less favorable outcome. Finally, one should proceed with serial I and Ds only under the condition that a predefined, aggressive protocol is applied. In conclusion, when treating a PJI of the hip or the knee, all the above factors should be considered in order to decide whether the patient is likely to benefit from this approach.

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

BACKGROUND: Patients with bilateral hip disease may undergo same-day or staged bilateral total hip arthroplasty (THA). Our purpose was to compare the odds and identify risk factors for deep periprosthetic joint infection (PJI) among patients undergoing same-day vs staged bilateral THA (within 1 year or more than 1 year apart). METHODS: Administrative data for patients subjected to same-day and staged bilateral THA between January 1999 and December 2013 were retrieved. Patients with subsequent PJI were identified. Mean follow-up was 112.6 months (range, 23-201). A logistic regression model was constructed to determine differences in odds for infection between groups and risk factors for PJI. RESULTS: We identified 1808 patients treated with same-day bilateral THA, 2082 patients treated with staged THAs within 1 year, and 2760 patients treated with staged THAs more than 1 year apart. Patients treated with same-day procedures had similar odds for PJI compared to those treated with staged THAs within 1 year (odds ratio [OR] = 0.632, 95% confidence interval [CI] [0.203, 1.962]), or more than 1 year apart (OR = 1.391, 95% CI [0.516, 3.746]). Women had 66.1% lower odds for PJI than men (OR = 0.339, 95% CI [0.16, 0.72]). Patients with inflammatory arthritis had 632% higher odds for PJI than patients with degenerative arthritis (OR = 7.321, 95% CI [1.912, 28.028]). Allogeneic transfusion was associated with 166% higher odds for PJI (OR = 2.661, 95% CI [1.198, 5.911]). CONCLUSION: Same-day bilateral THA is not associated with increased odds for PJI compared to staged procedures. Male gender, inflammatory etiology, and allogeneic transfusion are significant risk factors for PJI in patients undergoing same-day or staged bilateral THA.

Multiple Irrigation and Debridements for Periprosthetic Joint Infections: Facing a Necessity or Just Prolonging the Inevitable?

Irrigation and debridement (I&D) may be a viable option in selected cases of periprosthetic joint infections (PJI). Our aim was to investigate the role of multiple I&Ds. Among 141 patients with PJI treated with I&D in our institution, 19 were subjected to additional procedures. Their clinical characteristics were retrospectively reviewed and compared to the remaining patients treated with a single I&D. The probability of treatment failure (removal of implants) was not significantly different among the two groups. The interval between serial I&Ds was a significant factor determining outcomes. Patients treated with multiple I&Ds had a significantly higher prevalence of peripheral vascular disease. The decision to proceed with repeat of I&D should be made with caution.

Otto Aufranc Award: Large Heads Do Not Increase Damage at the Head-neck Taper of Metal-on-polyethylene Total Hip Arthroplasties.

BACKGROUND: Fretting and corrosion at head-neck junctions of total hip arthroplasties (THAs) have been associated with adverse local tissue reactions in patients with both metal-on-polyethylene (MoP) and metal-on-metal (MoM) prostheses. Femoral head size contributes to the severity of fretting and corrosion in large-diameter MoM THAs, but its impact on such damage in MoP THAs remains unknown. QUESTIONS/PURPOSES: (1) Is femoral head size associated with increased fretting or corrosion at the head-neck junction in MoP total hips? (2) Is duration of implantation associated with increased fretting or corrosion? METHODS: The severity of fretting/corrosion on surfaces of head tapers and stem trunnions was visually examined in 154 MoP THAs retrieved as part of 3282 revision surgeries performed at our institution between January 1, 2007, and December 31, 2013. Fretting and corrosion damage were subjectively graded by two independent observers on a 1 to 4 scale, and their relations to head size, alloy combinations, taper/trunnion design, length of implantation (LOI), and location were investigated. Differences in scores never exceeded one grade, and this occurred in only 17% of examined implants. With the available implants, the study provided 88% power to detect differences of 0.5 in fretting or corrosion scores in these analyses. RESULTS: Fretting and corrosion of the tapers and the trunnions were not affected by head size (p = 0.247, p = 0.471, p = 0.837, and p = 0.868, respectively), although taper/trunnion design affected taper fretting (p = 0.005) and corrosion (p = 0.0031) and trunnion fretting (p = 0.0028). Head taper fretting (observed in 73% of heads) increased with LOI, but head taper corrosion (noted in 93% of heads) was not affected. Trunnion fretting (observed in 86% of stems) was more severe in mixed-alloy combinations and with increased LOI and was more severe proximally. Trunnion corrosion (noted in 72% of stems) was also location-dependent with greater corrosion distally. CONCLUSIONS: Fretting and corrosion are regular occurrences in MoP THAs, but neither damage type was related to femoral head size. Conversely, taper design, LOI, and alloy combination affected the severity of both fretting and corrosion. CLINICAL RELEVANCE: Although it has been suggested that trunnion corrosion seen in MoP bearings is a function of larger diameter heads, our data suggest that larger femoral heads may be used for increased damage at the modular junction of MoP THAs.

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

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

Irrigation and debridement for periprosthetic infections of the hip and factors determining outcome.

PURPOSE: Our purpose was to identify the success rate and factors predicting outcome of irrigation and debridement (I&D) in patients with deep periprosthetic joint infection (PJI) of the hip. METHODS: We retrospectively reviewed clinical characteristics of patients with deep PJI after primary/revision total hip arthroplasty (THA) between January 2000 and May 2013 treated with I&D. Implant retention was the outcome of interest. Sixty patients (29 men and 31 women; mean age 64.9 years) were identified. Mean follow-up was 59 months (range, 12-168). RESULTS: The implants were retained in 42 patients (70%). Failure of I&D treatment correlated with duration of symptoms >five days (p <0.001) and obesity [body mass index (BMI) ≥ 30)] (p = 0.0289). Treatment outcome was affected by the type of pathogen (p = 0.0482), with patients with methicillin-resistant staphylococci having significantly lower odds of success. CONCLUSIONS: I&D can be a feasible option in THA patients presenting with acute deep PJI. Duration of symptoms >five days, isolation of methicillin-resistant staphylococci and obesity should be taken into consideration in pre-operative decision making.