, the pji is a significant ( or major ) cause of implant failure and requires multiple operations including revision arthroplasty89 ) . microorganism for pji could be originated not only from exogenous sources such as intraoperative contamination , but also from endogenous or hematogenous sources including remote site skin infection , urinary tract infection ( uti ) , and pneumonia in patient themselves1213141516 ) . among the endogenous sources , upper uti , including acute pyelonephritis and intra- /peri - renal abscess , should be treated prior to tha , because the upper uti can develop to uro - sepsis , and result in impairment of renal function20 ) . some authors reported that hip arthroplasty should be delayed until the treatment of uti , because patients with uti had a high risk of pji412171819 ) . but , others demonstrated that preoperative uti was not associated with pji1319 ) . to prevent an occurrence of pji , surgeons should identify the patients with high risk factors of pji2122 ) , and correct the modifiable factors prior to tha323 ) . however , unnecessary delays could result in dissatisfaction from patients who wait for tha2425 ) . our purposes were ( 1 ) to evaluate the incidence of pji after elective primary tha at a single institute and ( 2 ) to determine whether the lower uti was associated with a risk of pji after elective primary tha . after approval of institutional review board , we retrospectively reviewed the medical records of 544 patients ( 635 hips ) , who underwent primary tha by two high volume surgeons at a single institute from may 2003 to october 2007 . fifteen patients ( 15 hips ) who were treated for hip fracture and 2 patients who were treated for pathologic fracture were excluded , because they were not elective . the remaining 527 patients ( 618 hips ) were identified for elective primary tha . among 91 patients who underwent bilateral tha , 25 patients underwent simultaneous bilateral tha , and remaining 66 patients underwent staged bilateral thas . of the 593 procedures , uti group was defined as patients who underwent primary tha in status of having an uti , otherwise , they were defined as control group . during preoperative workups including complete blood count , electrolyte panel and urine analysis , uti was diagnosed if symptomatic patients have white blood cells greater than 110/ml or a bacterial count greater than 110/ml14 ) . if a patient was diagnosed with lower uti , urine culture was performed before tha and prophylactic antibiotics were started at the operation day . it was administered until identification of microorganism . if the patients had fever or leukocytosis , we delayed tha until the control of uti ( fig . the remaining 514 patients ( 580 procedures ) were classified as control group . in uti group , there were 11 females and 2 males with a median age of 57 years ( range , 25 - 74 years ) . the median of body mass index ( bmi ) was 26.7 kg / m ( range , 19.0 - 33.6 kg / m ) . in control group , there were 247 females and 273 males with a mean age of 51.0 years ( range , 19 - 83 years ) . their mean bmi was 24.2 kg / m ( range , 14.6 - 37.7 kg / m ) ( table 1 ) . during the study period , we performed all tha in operating rooms equipped with vertical laminar flow with the use of a hepa filter . each member of the surgical team put on a cap cover with string ( string hood cap ; km healthcare co. , guri , korea ) and a surgical jacket ( km healthcare co. ) ( fig . surgical scrub and skin preparation included the use of 2% chlorhexidine - alcohol and aqueous solutions of 10% povidone - iodine ( povidin ; sung kwang pharm , bucheon , korea ) . after then , we used an incise adhesive drape ( ioban ; 3 m corporation , st . we used prophylactic intravenous antibiotics within 1 hour of the tha and for 7 days postoperatively . we performed tha through a posterolateral approach in 289 procedures , modified anterolateral approach in 260 procedures , and combined approach in 31 procedures . closed suction drains were used in all cases , and removed at 2 or 3 days postoperatively . postoperative wound management included utilization of a sterile dressing that was applied to the incision in the operating room and usually changed at 2 days postoperatively . the wound was evaluated and the sterile gauze was changed twice a week for 1 week to 2 weeks in the ward . during hospitalization , thigh - length antiembolic stockings were applied and the ankle pump was encouraged without any pharmacological thromboprophylaxis . after discharge , patients were routinely followed up on their 6th week , 3rd , 6th , and 12th month and every 1-year thereafter . the diagnosis of pji was made by musculoskeletal infection society criteria , which is gold standard to diagnose pji ( table 2)27 ) . we also evaluated sex , age , bmi , type of anesthesia ( regional or general ) , co - morbidity assessed by american society of anesthesiologists ( asa ) score , and operation time to determine the relationships between these variables and the development of pji . chi - square test was used for categorical variables . the spss version 16.0 ( spss inc . , two patients have deceased and 12 patients were lost during follow - up before the minimum 12 months postoperatively . we evaluated 513 patients ( 579 procedures ) , who could be followed up at the minimum of 12 months . among the 579 procedures , we evaluated the overall incidence of pji and the association of lower uti and pji after elective primary tha . the overall incidence of pji was 0% in our study , regardless of existence of lower uti . many of studies have reported the incidence of pji ranges from 0.2% to 1%34567 ) . in our series universal aseptic technique and well - established facility might be a reason for the absence of pji in this study . in addition , we did not use routine chemical thromboprophylaxis , which has been considered as a risk of pji28 ) . although several studies recommended the use of chemical thromboprophylaxis after tha , we did not do so as venous thromboembolism is uncommon in east asian patients after tha2930 ) . impaired immune status , systematic disease such as rheumatoid arthritis , lupus , diabetes , and malignancy , advanced age , malnutrition , obesity , previous joint infection , longer operation time , and longer preoperative hospitalization have been reported to be associated with a risk of pji2122 ) . in this study the presence of remote site infection might be associated with pji , and we agreed that it should be identified and controlled before surgery , especially in those with fever or leukocytosis . generally , fever and leukocytosis could be considered as surrogate parameter of systemic bacteremia , which might result in hematogenous pji20 ) . however , a prospective randomized comparative study is barely possible in this topic , because of ethical issue . third , there might be a selection bias , because our hospital is a referral - only university - hospital with high quality equipment . our results showed that cautiously performed tha can have a very low incidence of pji , and lower uti was not associated with a risk of pji when tha was cautiously performed with universal aseptic technique .