Monitoring Method for Deep Infection after TKA: Significance of Intraoperative Synovial Fluid Culture and Postoperative Suction Drainage Tip Culture / 대한정형외과학회잡지

PURPOSE: The aim of this study was to evaluate the usefulness of the intra-operative synovial fluid culture and post-operative suction drainage tip culture as a method for predicting the development of a deep infection after primary TKA. MATERIALS AND METHODS: Between July 1998 and July 2002, 324 primary total knee arthroplasty procedures were performed and aerobic and anaerobic bacterial cultures for intra-operative synovial fluid and post-operative suction drainage tip were obtained. The results of culture of intra-operative synovial fluid and post-operative suction drainage tip of total 324 primary TKA cases were analyzed. The sensitivity, specificity and predictive value were calculated. positive culture rate for osteoarthritis was compared with rheumatoid arthritis and the results of a single TKA was compared with both simultaneous TKA. RESULTS: 14 out of 324 knees showed a positive intra-operative synovial fluid culture and 10 cases showed a positive post-operative suction drainage tip culture. Only 1 case out of the 4 deep infection cases showed a positive on suction drainage tip culture with S. aureus being isolated. The specificity of the intra-operative synovial culture was 95.6% and the negative predictive value was 98.7%. The sensitivity of the post-operative suction drainage tip culture was 25%, the specificity was 97%, the positive predictive value was 10% and the negative predictive value was 99%. The positive culture rate was similar in the osteoarthritis and rheumatoid arthritis cases (respectively p=0.4717, p=0.6550). However, the culture positive rate between single and both simultaneous TKA was numerically different, approximately 2 times (3.2% vs 6.31% for intra-operative synovial culture and 4.0% vs 9.47% for post-operative suction drainage tip culture) but it was not statistically significant (respectively p=0.311, p=0.1051). CONCLUSION: In primary TKA, a culture of intra-operative synovial fluid and post-operative suction drainage tip cannot predict a postoperative deep wound infection. It is recommended that careful observation for other signs of a deep infection be examined when a clinically significant true pathogen isisolated.

Monitoring for Deep Wound Infection after Thoracolumbar Surgery Significance of Suction Drainage Tip Culture for Early Detection of Postoperative Deep Wound Infection / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To evaluate the usefulness of postoperative suction drainage tip cultures as a method of predicting the development of deep wound infections after thoracolumbar surgery using pedicle screws. SUMMARY OF LITERATURE REVIEW: The primary diagnostic elements of post-operative spinal infections are a high degree of clinical suspicion by the surgeon combined with aspiration and culture of the suspected infection sites. MATERIALS AND METHODS: We analyzed the results of cultures on postoperative suction drainage tips from a total of 471 thoracolumbar surgery cases. We calculated the sensitivity, specificity, and predictive value and investigated the isolated pathogens. In addition, we performed quantitative analyses of serum C-reactive protein using Turbidimetry. RESULTS: The post-operative infection rate was 4.0%. The most common isolated pathogen of the true positive cases was staphylococcus aureus, which was found in 3 cases (methicillin-resistant staphylococcus aureus in 2 cases); and that of the false positive cases was coagulase-negative staphylococcus in 5 cases. The sensitivity of the suction drainage tip culture was 52.6%, the specificity was 96.3%, the positive predictive value was 37.0%, and the negative predictive value was 98.0%. In cases of C-reactive protein, true positive and false negative cases followed the same course, where the CRP decreased slowly for the first week but remained elevated persistently at the 14th postoperative day. CONCLUSIONS: Culture of the suction drainage tips could not predict the development of postoperative deep wound infections, but it had more significance in the exclusion of deep wound infections. We concluded that careful observation for other signs of deep wound infections are necessary when a clinically significant pathogens are isolated.