The clearance of gentamicin from antibiotic-loaded bone cement

Retention of Antibiotic Cement Delivery Implants in Orthopedic Infection Associated With United Fractures Does Not Increase Recurrence Risk

OBJECTIVES

To evaluate whether retention of antibiotic cement delivery devices after resolution of orthopaedic infection is associated with recurrence.

METHODS

DESIGN

Retrospective cohort.

SETTING

Academic medical center.

PATIENT SELECTION CRITERIA

Patients with a fracture definitively treated with internal fixation that went on to unite and develop a confirmed fracture-related infection or osteomyelitis after a remote fracture surgery and had implantation of antibiotic-impregnated cement for infection management.

OUTCOME MEASURES AND COMPARISONS

Patients were divided into whom the antibiotic implants were retained (Retained Cohort) and whom the antibiotic implants were removed (Removed Cohort). Outcome measures included clinical infection resolution, infection recurrence, time to resolution of infection signs, symptoms and laboratory values, reoperation and readmission rates, and need for soft tissue coverage (local flap vs. free tissue transfer) because of recurrence.

RESULTS

Of 98 patients treated for fracture-related infection in united fractures or osteomyelitis after a remote fracture surgery, 39 (39.8%) underwent implantation of antibiotic-impregnated cement delivery devices: 21 (21.4%) beads, 7 (7.1%) rods, and 11 (11.2%) blocks. Twenty patients (51.3%) comprised the Retained Cohort and 19 patients (48.7%) comprised the Removed Cohort. There were few differences in demographics ([American Society of Anesthesiology Score, P = 0.026] and [diabetes, P = 0.047]), infection location, and pathogenic profiles. The cohorts demonstrated no difference in eventual resolution of infection (100% in the Retained Cohort, 95% in the Removed Cohort, P = 0.487) and experienced similar time to clinical infection resolution, based on signs, symptoms, and laboratory values ( P = 0.360). There was no difference in incidence of subsequent infection recurrence after clinical infection resolution (1 recurrence Retained vs. 2 recurrences Removed, P = 0.605) for those considered "cured." Compared with the Retained Cohort, the Removed Cohort underwent more reoperations (0.40 vs. 1.84 reoperations, P < 0.001) and admissions after implantation ( P < 0.001).

CONCLUSIONS

Retention of antibiotic-impregnated cement delivery devices in patients with orthopaedic infection after fractured bones that have healed was not associated with infection recurrence. Additional surgical intervention with the sole purpose of removing antibiotic delivery devices may not be warranted.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Two-stage revision of infected hip prosthesis after post-operative antibiotic therapy: An observational study

Infection is a major threatening side effect after total hip arthroplasty (THA) that its management is so difficult and is accompanied by different complications. The aim of this study was to determine the outcomes of patients underwent 2-staged THA after a course of antibiotic therapy. It was an observational prospective study performed during 2009 and 2019. We managed 51 patients with infected THA using a method in which antibiotic prophylaxis was performed after THA. We followed the same protocol for treatment of patients included 2-staged revision: in first stage, removal of infected instruments were performed and insertion of a hand-made antibiotic-cement spacer was done until erythrocyte sedimentation rate and CRP were normalized. In second stage, an un-cemented prosthesis was re-implanted in femoral side and post-operative IV antibiotic were administered for a week. Patients were monitored for about 15 months. Data were analyzed. There were 3 patients developed recurrent infection required girdlestone due to the aging. One of them needed to remove implant and 2 other with 3 times of re-infection were treated by antibiotic therapy. Other 10 cases were treated first by re-changing the cement. The rate of successful treatment was 78.4% (40 of 51) after the primary surgery and antibiotic therapy. This rose to 92.1% (47 of 51) following more debridement and antibiotic therapy. The merging of staged surgical debridement, using spacer of cement-antibiotic and re-implant beside 1-week intravenous antibiotic therapy, leaded to appropriate early outcomes in this series.

Current Concepts on the Application, Pharmacokinetics and Complications of Antibiotic-Loaded Cement Spacers in the Treatment of Prosthetic Joint Infections

Prosthetic joint infection (PJI) is a devastating complication of total joint replacement surgery. It affects about 2% of primary total joint replacements. Treatment aims at infection eradication and restoration of patient's mobility. Two-stage revision arthroplasty with an interim application of an antibiotic-loaded cement spacer (ALCS) is the widely accepted treatment for PJI. Spacers are powerful local carriers of antibiotics at the site of infection, effective against biofilm-protected microbes. On the other hand, spacers permit some mobility of the patient and facilitate final prosthesis implantation. ALCS's are either commercially available or prepared intraoperatively on prefabricated or improvised molds. Antibiotic elution from the spacer depends on the amount of the antibiotic used for cement impregnation, at the expense of mechanical stiffness of the spacer. The antibiotic should not exceed 4g per 40g of bone cement to preserve the mechanical properties of the cement. Spacers are frequently accompanied by local or systemic complications. The spacer may break, dislocate and compress vessels or nerves of the limb. Systemic complications are the result of excess elution of antibiotic and include nephrotoxicity, hepatotoxicity, ototoxicity, allergic reactions or neutropenia. Elderly patients with comorbidities are at risk to present such complications. Microbial resistance is a potential risk of long-lasting spacer retention. Persisting infection may require multiple spacer replacements.

Cement mantle thickness does not influence serum or local gentamicin concentrations in hybrid total hip arthroplasty: a randomised controlled trial

INTRODUCTION

We investigated the in vivo gentamicin elution kinetics of Hi-Fatigue Gentamicin Bone Cement (AAP Biomaterials GmbH) in serum and drain fluid after hybrid hip arthroplasty and the relationship with cement mantle thickness.

METHODS

We compared in a randomised, non-blinded prospective study, the local and systemic gentamicin concentrations in 2 groups. The thin cement mantle group ( n = 16) received a stem implanted line-to-line with the broach, whereas the thick group ( n = 14) had an undersized stem. Gentamicin concentrations were measured in drain fluid and serum at set intervals for 3 days postoperatively.

RESULTS

In both groups, local gentamicin concentrations were similar. After a high initial burst above the minimal inhibitory concentration (thin: 57.2 mg/L (SD 34.4), thick: 54.9 mg/L (SD 19.9), p = 0.823) local gentamicin concentrations declined rapidly. In both groups, serum concentrations never exceeded toxic levels (maximum 1.08 mg/L).

CONCLUSION

In hybrid total hip arthroplasty, Hi-Fatigue Gentamicin Bone Cement resulted in effective and safe gentamicin concentrations. Clinical trial protocol number: PMCI 12/02.

Systemic exposure to tobramycin after local antibiotic treatment with calcium sulphate as carrier material

INTRODUCTION

Osteoset(®) T is a calcium sulphate void filler containing 4% tobramycin sulphate, used to treat bone and soft tissue infections. Despite systemic exposure to the antibiotic, there are no pharmacokinetic studies in humans published so far. Based on the observations made in our patients, a model predicting tobramycin serum levels and evaluating their toxicity potential is presented.

METHODS

Following implantation of Osteoset(®) T, tobramycin serum concentrations were monitored systematically. A pharmacokinetic analysis was performed using a non-linear mixed effects model based on a one compartment model with first-degree absorption.

RESULTS

Data from 12 patients treated between October 2006 and March 2008 were analysed. Concentration profiles were consistent with the first-order slow release and single-compartment kinetics, whilst showing important variability. Predicted tobramycin serum concentrations depended clearly on both implanted drug amount and renal function.

DISCUSSION AND CONCLUSION

Despite the popularity of aminoglycosides for local antibiotic therapy, pharmacokinetic data for this indication are scarce, and not available for calcium sulphate as carrier material. Systemic exposure to tobramycin after implantation of Osteoset(®) T appears reassuring regarding toxicity potential, except in case of markedly impaired renal function. We recommend in adapting the dosage to the estimated creatinine clearance rather than solely to the patient's weight.

Backgrounds of antibiotic-loaded bone cement and prosthesis-related infection

Antibiotic-loaded bone cement has been in use for over 30 years for the fixation of total joint arthroplasties, although its mechanism of action is still poorly understood. This review presents the backgrounds of bone cements, prosthesis-related infection and antibiotic-loaded bone cements. It is shown that antibiotic-loaded bone cement has a significant effect on bacteria, particularly in animal and clinical studies. However, recently, antimicrobial resistance among bacteria has been ascribed to the antibiotic-loaded bone cement. The unresolved issues both regarding the action of antibiotic-loaded bone cement and the nature of the antimicrobial resistance necessitate further research into the interaction of antibiotic-loaded bone cement and bacteria.

Comparative study of gentamicin release from normal and low viscosity acrylic bone cement

The pharmacokinetics of gentamicin were studied after total hip joint arthroplasties in 2 groups of 10 patients. The prosthesis was performed in the first group with 'Palacos R plus gentamicin' (normal viscosity), manufactured by Schering, and in the second group with 'Cerafix genta R' (low viscosity) manufactured by Ceraver-Osteal. Both cements included similar concentrations of gentamicin. Urine was collected at 12-hour intervals for 15 days after operation, and drainage fluids for 48, 72 or 108 hours. Blood samples were taken 3 and/or 5 hours after prosthesis implantation. In both cases, high concentrations of gentamicin were found in drainage fluids and urine during the early postoperative period. Mean gentamicin excretion curves were calculated by a computer-aided design program (SIAM) for the 2 cements. The release of gentamicin was biphasic in both cases, although the slow elimination phase appeared to be longer for 'Cerafix'. In the first postoperative period, the drug had a better bioavailability during the rapid elimination phase in the case of 'Palacos'. The calculated peak blood concentration was in the same range for both compounds. The conclusion is drawn that, in patients undergoing total hip joint arthroplasties, gentamicin concentrations reach local levels higher than the minimum inhibitory concentrations of most of the likely sensitive pathogens. However, in both cases, as blood concentrations appear to be low, patients will not be protected against systemic infections. Both cements have similar antibacterial properties but the mechanical properties of 'Cerafix' are the better of the two.