Successful Two-Stage Exchange Arthroplasty for Periprosthetic Infection Following Total Knee Arthroplasty: The Impact of Timing on Eradication of Infection

Background: Periprosthetic joint infection (PJI) represents a serious complication following total knee arthroplasty. In the setting of chronic infections, the two-staged approach has traditionally been the preferred treatment method. The aim of this study was to determine the optimal period of rest between the first and second stage. Furthermore, we analyzed potentially outcome-relevant parameters, such as general and local conditions and the presence of difficult-to-treat or unidentified microorganisms, with regard to their impact on successful treatment of PJI.Patients and Methods: We performed a retrospective analysis of prospectively collected data for all patients treated for PJI at our institution. Seventy-seven patients who had undergone two-stage revision arthroplasty for PJI of the knee were included into the study. Antibiotic-loaded cement spacers were used for all patients.Results: After a median follow-up time of 24.5 months, infection had reoccurred in 14 (18.7%) patients. A prolonged spacer-retention period of more than 83 days was related to a significantly higher proportion of reinfections. Furthermore, significant compromising local conditions of the prosthetic tissue and surrounding skin, as well as repeated spacer-exchanges between first- and second-stage surgery, negatively influenced the outcome. Neither the patients'' age nor gender exerted a significant influence on the outcome regarding reinfection rates for patients'' age or gender.Conclusions: We observed the best outcome regarding infection control in patients who had undergone second-stage surgery within 12 weeks after first-stage surgery. Nearly 90% of these patients stayed free from infection until the final follow-up. An increased number of performed spacer-exchanges and a bad local extremity grade also had a negative impact on the outcome.     

Migration of the acetabular component: effect of cement pressurization and significance of early radiolucency: a randomized 5-year study using radiostereometry

BACKGROUND: Cementing technique is a crucial factor in prosthesis fixation. No randomized studies have been published, however, comparing the outcome of conventional fingerpacking with the outcome of pressurization of the cement prior to cup insertion. PATIENTS AND METHODS: We randomized 50 THAs to either fingerpacking or sequential pressurization (including individual pressurization of each anchorage hole) and followed the patients with RSA for 5 years. The penetration of cement into the anchorage holes was measured on digital radiographs. Postoperative radiolucent lines around the cup were correlated to later RSA results. For clinical evaluation, we used SF-36 and HHS. RESULTS: The pressurized group of THAs was more stable regarding changes in inclination. We found no other difference in the migratory behavior. The cement penetration into the anchorage holes was deeper with the pressurization technique than with fingerpacking. For the whole group taken together, there was a strong relation between the presence of radiolucent lines as measured on the postoperative radiograph and later migration observed by RSA at 2 and 5 years. INTERPRETATION: Pressurization of the cement produced better cement penetration and increased the cup stability in terms of changes in inclination. Early findings of radiolucent lines can predict later unfavorable cup migration.     

Liposuction: a less invasive surgical method of debulking plexiform neurofibromas

BACKGROUND: Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder in humans. The hallmark of NF1 is development of neural tumors. Plexiform neurofibromas are a major source of morbidity associated with NF1. Surgical removal of these particular tumors is associated with a high risk of damage of surrounding vital structures as well as a risk of significant hemorrhage. Surgical debulking of tumors also sometimes leads to extensive scarring, which may be very disfiguring. OBJECTIVE AND METHODS: We report a novel approach to the surgical therapy of plexiform neurofibromas using liposuction in two patients. RESULTS: Debulking of plexiform neurofibromas with liposuction was successful in both patients. Postoperative follow-up 6 months later showed no evidence of tumor regrowth in either case. CONCLUSION: Liposuction may be a preferable surgical method for debulking of superficial plexiform neurofibromas in patients with NF1. This method is less invasive than conventional surgical tumor debulking.     

A randomized comparison of paclitaxel-eluting stents versus bare-metal stents for treatment of unprotected left main coronary artery stenosis.

OBJECTIVES: To optimize percutaneous coronary intervention (PCI) strategy for unprotected left main (LM) disease, we performed a randomized study: intravascular ultrasound (IVUS)-guided bare-metal stent (BMS) or paclitaxel-eluting stent (PES) implantation after lesion pre-treatment with cutting balloon (CB) for unprotected LM lesions. BACKGROUND: Recent studies have shown promising results in terms of safety and feasibility for patients with LM disease who underwent PCI with stent implantation. However, comparison of BMS and PES for LM lesions has not yet been evaluated. METHODS: One hundred three patients were randomly assigned to receive BMS (n = 50) or PES (n = 53) implantation. All interventions were IVUS guided, and CB pre-treatment before stenting was performed in all patients. All patients were scheduled for 6-month follow-up. RESULTS: Baseline clinical characteristics were comparable in both cohorts. Stent implantation was successful in all lesions. Follow-up analysis showed binary restenosis in 11 (22%) BMS and in 3 (6%) PES patients (p = 0.021). By IVUS, percentage of neointimal volume obstruction at 6 months was reduced from 25.20 +/- 22.02% with BMS to 16.60 +/- 17.25% with PES (p = 0.02). At 6 months, the major adverse cardiac event-free survival rate was 70% in BMS and 87% in PES patients (p = 0.036). CONCLUSIONS: This study demonstrates that PCI of LM with IVUS guidance and CB pre-treatment is safe and effective. No serious procedure-related complications were observed, and clinical outcomes appeared to be good. Finally, the findings demonstrate that implantation of PES may be superior to BMS in the large-diameter LM vessel at 6 months, warranting the performance of a large-scale randomized trial.     

EBRA improves the accuracy of radiographic analysis of acetabular cup migration

EBRA (Ein Bild Rontgen Analyse) is a new computerized method measuring migration and wear of the acetabular cup, suggested to improve measurement accuracy. We evaluated possible errors of measurement and compared EBRA with standard methods.

1. We did repeated measurements on a single radiograph using the same reference lines. The reliability of the input procedure with standard measurements was significantly better than repeated digitization with EBRA.

2. In a more clinical test, a group of 10 patients was studied. 5 radiographs were taken of the same patient on the same day. EBRA improved the reliability of repeated radiographic examination significantly for migration measurements in the vertical direction.

3. To assess the inter- and intraobserver variations, repeated measurements were performed on the clinical series of pelvic radiographs of 10 patients. EBRA was significantly better than standard methods.

With EBRA, errors of wear and migration measurements could be reduced, as compared to standard methods. The major improvement with EBRA was found for migration measurements in the vertical direction.     

Femoral head diameter affects the revision rate in total hip arthroplasty: an analysis of 1,720 hip replacements with 9-21 years of follow-up

Background In a previous study concerning 1,660 ScanHip THAs that were followed for up to 12 years, the cumulative revision rate was not found to be dependent on whether a 22-mm or a 32-mm head size had been used. We have re-examined these patients to see whether a longer follow-up time (9-21 years) would disclose an effect of head size on the revision rate.

Patients and methods We analyzed the cumulative revision rate for 1,720 Scan Hip arthroplasties with either 22-mm or 32-mm femoral heads. The patients were followed for 9-21 years.

Results Arthroplasties with 32-mm head had 2.8-times higher cumulative revision rate than those with a 22-mm head. Older age reduced the risk of revision while male sex increased the risk.

Interpretation We found that head size affects revision risk, but that even in a reasonably large material a long follow-up time is required to disclose the effects of head size—and thus wear—on survival.     

Effect of aromatic carcinogens and noncarcinogenic analogs on the induction of murine αβ interferon

The effects of several aromatic carcinogens and their noncarcinogenic analogs on the production of $\text{α}\text{β}$ interferon by mouse embryo fibroblasts were determined. The carcinogens 2-naphthylamine and 9,10-dimethylanthracene significantly depressed $\text{α}\text{β}$ interferon production, while their poorly or noncarcinogenic analogs, 1-naphthylamine and anthracene, respectively, had no significant effect. Neither the carcinogen benzidine nor its poorly carcinogenic analog 3,3′,5,5′-tetramethylbenzidine had any effect on $\text{α}\text{β}$ interferon production. These data, taken together with previous findings, suggest the possibility of drawing a high correlation between the carcinogenic potential of a chemical and its effect on interferon production.