Positioning of the wrist for scaphoid radiography.

PURPOSE: The purpose of this cadaver study was to determine the ideal position of the wrist for scaphoid radiography. MATERIALS AND METHODS: Four cadaver wrists were rotated around their longitudinal axis in 15 degrees increments and exposures were taken. Seven postero-anterior images were taken as well. Thus, 18 images of each wrist were available for assessment. Views were determined in which the main anatomic regions of the scaphoid were visualized undistorted. The size and localization of the overlap of other carpal bones were also evaluated. Finally, views with the best visualization of anatomic landmarks were selected. The results of these three investigations were compared to literature data. RESULTS: We consider the following four images the most valuable in the diagnostic imaging of scaphoid bone: (1) Postero-anterior view in ulnar deviation of wrist and fist position of the hand; (2) oblique view in 60 degrees of pronation; (3) oblique view in 60 degrees of supination; (4) lateral view. CONCLUSION: We concluded that our four views are sufficient for proper radiographic evaluation of the scaphoid.

Detection of gentamicin emission from bone cement in the early postoperative period following total hip arthroplasty.

This article describes the characteristics of gentamicin emission from the bone cement-antibiotic complex in the early postoperative period following total hip arthroplasty. Gentamicin levels of the drain fluid taken at 6, 24, and 48 hours postoperatively were measured with a fluorescent polarization immunoassay method. Mean gentamicin concentrations were 2.6, 1.2, and 0.6 mcg/mL, respectively. Age, sex, and body mass index had no significant influence on the outcome. Results showed that the amount of gentamicin in the wound fluid is inversely proportional to the total amount excreted. Twenty-four hours postoperatively, the average gentamicin concentrations in the drain fluid taken from around the endoprosthesis implanted with Palacos-R bone cement (Zimmer Warsaw, Ind), diminished, yet remained above the minimal inhibitory concentration level.

Repair of steps and gaps in articular fracture models.

To examine the healing of surface defects in articular fractures, gaps measuring 0.5 mm wide and 2 mm deep were created in 0.5-mm coronal step-offs on the medial femoral condyles of 16 rabbits, and identical gaps without step-offs were created in another set of 13 rabbits. Evaluation of repair was done 6, 12, and 24 weeks postoperatively. Histologically, subchondral bone restoration of gaps in step-offs was complete by 24 weeks, whereas restoration was incomplete in most gap-only lesions. Bone density measured by peripheral quantitative computed tomography was normal in gaps in step-offs by 24 weeks, but values were less than in controls in the gap-only group. A moderate degree of degeneration was detected only at the high sides of step-off + gap lesions. The joint surface was restored by fibrous cartilage that showed gradually improving maturity in all defects, however, real integration with adjacent original cartilage did not occur. Immunohistologic examination showed decreasing collagen Type I and increasing Type II staining intensity in repair tissue of both types of lesions. These observations suggest that minor surface gaps and steps of articular fractures may regenerate without inducing severe early joint degeneration. However, certain repair features make the long-term outcome of these defects uncertain.

In vitro measurement of the time-related efficacy of gentamicin sulfate release from bone cements.

BACKGROUND: The aim of the present study was to establish an in vitro microbiologic monitoring system which measures the dynamics of antibiotic release from acrylic bone cement and its antibacterial efficacy. METHODS: Palacos R and Orthofix R cements containing gentamicin sulfate were tested. The in vitro elution dynamics was analyzed by plate diffusion method during a 1-year period after mixing. High but rapidly decreasing antibiotic levels were detected within the 1st week, resulting in an almost steadily low concentration by the end of the 1st month. After 1 year, it was still possible to demonstrate the inhibitory effect of the drug from both cements. Comparison of the time-related release between the antibiotics failed to find any statistically significant differences. CONCLUSION: The method described is a useful and reproducible technique for the in vitro measurement of the inhibitory activity of antibiotic released from bone cements.

[The comparison of in vivo and in vitro elution of gentamycin from bone cement]. / Gentamicin csontcementbol történo in vivo és in vitro emissziójának összehasonlítása.

INTRODUCTION: The authors report their in vivo and in vitro results of the elution characteristics of gentamycin sulfate from bone cement, which is the most commonly used way of local antibiotic prophylaxis in Europe in the field of orthopedic surgery. AIM: The aim of this study was to investigate the elution of the gentamycin sulfate from bone cement, describe the dynamics of the emission in time and evaluate the relationship between the minimal inhibitory concentration (MIC) and the eluted concentration of the antibiotic. METHODS: The in vivo investigation samples were taken from 9 patient from drain fluids to evaluate the eluted antibiotic concentration by fluorescent polarisation immunoassay method (FPI). The in vitro emission-dynamics of two different bone cement-Gentamycin sulphate complex were analysed by plate diffusion method during one-year period after mixing. RESULTS: Their results showed that 24 hours after the operation the gentamycin concentrations in the drain fluid taken from around the endoprosthesis implanted with Palacos-R bone cement diminished, yet remained above the MIC level. High but rapidly decreasing antibiotic level was detected by the in vitro method within the first week, reading an almost steadily low concentration by the end of the first month. Surprisingly, after one year it was still possible to demonstrate the inhibitory effect of the drug from both tested types of cements. CONCLUSIONS: It is concluded that the gentamycin is able to elute from the bone cement in useful concentration after the implantation of endoprosthesis. However, this in vitro method is a useful and reproducible technique for the measurement of the efficacy of antibiotic emission from bone cement, the conversation of the results to the in vivo remains to be obscured. Nevertheless, the usage of local antibiotic prophylaxis seems to be useful during orthopaedic major intervention.