[The method and result analyses of pathogenic bacteria culture on chronic periprosthetic joint infection after total knee arthroplasty and total hip arthroplasty].

OBJECTIVE: To analyze the results of pathogenic bacteria culture on chronic periprosthetic joint infection after total knee arthroplasty (TKA) and total hip arthroplasty (THA). METHODS: The medical data of 23 patients with chronic periprosthetic joint infection after TKA or THA from September 2010 to March 2014 were reviewed. Fifteen cases of TKA and 8 cases of THA were included in this study. There were 12 male and 11 female patients with the mean age of 62 years (range from 32 to 79 years), and among them 9 patients with sinus. All patients discontinued antibiotic therapy for a minimum of 2 weeks before arthrocentesis, taking pathogenic bacteria culture and antimicrobial susceptibility test by using synovial fluid taken preoperatively and intraoperatively of revision. Common pathogenic bacteria culture and pathological biopsy were taken on tissues intraoperatively of revision. Culture-negative specimens were prolonged the period of incubation for 2 weeks. RESULTS: The overall culture-positive rate of all 23 patients for 1 week before revision was 30.4% (7/23), and the positive rate of culture-negative samples which prolonged for 2 weeks was 39.1% (9/23). The overall culture-positive rate of patients for 1 week intraoperatively of revision was 60.9% (14/23), and the positive rate of culture-negative samples which prolonged for 2 weeks was 82.6% (19/23). The incubation results of 7 cases (30.4%) preoperatively conformed to that of intraoperation. CONCLUSION: The culture-positive rate of pathogenic bacteria culture can be increased evidently by discontinuing antimicrobial therapy for a minimum of 2 weeks prior to the definite diagnosis.

[Effect of femoral offset change on pain and function after total hip arthroplasty].

OBJECTIVE: To investigate the effects of altering the femoral offset after total hip arthroplasty on postoperative pain and function. METHODS: A total of 162 patients undergoing single total hip arthroplasty between March 2009 and December 2011 met the inclusion criteria. According to difference of femoral offset between operative side and contralateral side, the patients were divided into 3 groups: decreased offset group (< 5 mm, 30 cases), normal offset group (-5-5 mm, 87 cases), and increased offset group (> 5 mm, 45 cases). There was no significant difference in gender, age, and disease duration among 3 groups (P > 0.05). The types of femoral stem and head prosthesis were compared among 3 groups. Short Form 12 Health Survey (SF-12) score, Western Ontario and McMaster University Osteoarthritis Index (WOMAC) score, and Harris score were used to evaluate the clinical outcomes. RESULTS: Standard offset femoral prosthesis was most used, followed by increased offset femoral prosthesis, and decreased offset femoral prosthesis was least in 3 groups. The types of femoral stem and head prosthesis showed no significant difference among 3 groups (P > 0.05). The patients were followed up 12-33 months (mean, 25 months). There was no significant difference in SF-12 score among 3 groups at 1 year after operation (P > 0.05); there was no significant difference in WOMAC pain and stiffness scores among 3 groups (P > 0.05) except WOMAC body function score (P < 0.05). According to Harris scoring criteria, the results were excellent in 13 cases, good in 8 cases, fair in 7 cases, and poor in 2 cases in decreased offset group; the results were excellent in 42 cases, good in 34 cases, fair in 9 cases, and poor in 2 cases in normal offset group; the results were excellent in 31 cases, good in 12 cases, and fair in 2 cases in increased offset group; and significant difference was found among 3 groups (Z= -3.152, P=0.008). CONCLUSION: Increased offset is more conducive to joint functional recovery and pain relief; decreased offset may lead to joint function deterioration and pain aggravation.