Pharmacokinetics of topical gentamicin in total hip arthroplasty

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.

Is serum gentamicin concentration modified with autologous cell-saved blood transfusion after total knee arthroplasty using tranexamic acid? A randomised control trial

BACKGROUND

Self-transfusion has been proven as an effective management of blood loss after total knee arthroplasty (TKA). Considering that the high local concentration of antibiotic from bone cement is delivered intravenously through the self-transfusion process, systematic toxicity has never been evaluated. In addition, the effectiveness of self-transfusion with the routine concomitant use of other modern blood-salvage strategies, like tranexamic acid, should also be assessed. Therefore, we performed a randomised study to assess: 1) the safety of self-transfusion in TKA by comparing the gentamicin concentrations resulting from the use or not of autologous blood transfusion; 2) the efficacy of self-transfusion in TKA, with the concomitant administration of tranexamic acid.

HYPOTHESIS

Self-transfusion in TKA elevates the serum gentamicin concentration and the potential risk of nephrotoxicity.

METHODS

The serum concentration of aminoglycosides was measured in two groups of 20 patients each, after TKA, according to the use of self-transfusion. Hemoglobin, renal function and calculated blood loss were compared at several points in time between groups.

RESULTS

The only time where there was a statistically significant difference in serum gentamicin, was at 48h postoperatively between groups [0.3 ug/mL±0.21, range: 0.15 to 0.72 vs. 0.14ug/mL±0.1, range: 0 to 0.35 (p=0.02)]. There were no significant differences in total blood loss [1341mL±501, range: 830 to 2230 vs. 1263mL±459 range: 840 to 2480 (p=0.67)] and need of allogeneic blood transfusion [3 units vs. 2 units] between groups.

CONCLUSION

The use of autologous blood transfusion was found to be safe, in terms of nephrotoxicity of aminoglycosides after TKA, but it seemed to be ineffective as a blood salvage strategy, when used concomitantly with the administration of tranexamic acid.

LEVEL OF EVIDENCE

II; low-powered randomised study. CLINICALTRIALS.

GOV REGISTRATION NUMBER

NCT04505748.

The management of periprosthetic infections in the future: a review of new forms of treatment

The number of arthroplasties being undertaken is expected to grow year on year, and periprosthetic joint infections will be an increasing socioeconomic burden. The challenge to prevent and eradicate these infections has resulted in the emergence of several new strategies, which are discussed in this review. Cite this article: Bone Joint J 2015;97-B:1162-9.

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.

Reinfusion of whole blood following addition of tobramycin powder to the wound during total knee arthroplasty

This study prospectively examined nine human volunteers who underwent unilateral cementless total knee arthroplasty and had 600 mg of tobramycin powder added to their wound just prior to fascial closure. Serum levels of tobramycin were measured at 30 minutes, 4 hours, 8 hours, and 12 hours after surgery. Tobramycin levels in the reinfused whole blood were measured with each reinfusion. Patients were reinfused up to 12 hours after surgery and then the reservoir was left to suction drainage. All patients had significant levels of serum tobramycin 30 minutes after surgery. The average serum level was 5.5 micrograms/ml (range, 3.0-10.6 micrograms/ml). This level was achieved prior to any reinfusion and represented systemic absorption of tobramycin from the bleeding surfaces of the muscle and bone. All patients received at least one reinfusion of 400 ml of whole blood in the first 8 hours after surgery. Two thirds of the patients received a second reinfusion within the same time frame. Serum tobramycin levels measured post-reinfusion indicated that the risk of attaining potential toxic levels of aminoglycoside was not dependent on reinfusion, but on absorption from the wound. The dose of tobramycin in the drain was measured and found to be excessive and potentially toxic (range, 27-312 mg; average, 132 mg). Despite this fact, reinfusion was not as likely to produce toxic serum levels as was local uptake of the antibiotic. Although no patient in this series had any complaints relating to the high dose of tobramycin (deafness or renal failure), caution should be exercised when using antibiotics in a reinfusion system.(ABSTRACT TRUNCATED AT 250 WORDS)

Bactericidal activity of gentamicin against S. aureus. In vitro study questions value of prolonged high concentrations

Bactericidal activity of gentamicin against 4 strains of Staphylococcus aureus was investigated in vitro using Mueller-Hinton broth (MH) and surgical wound fluid (WF) as test media. 6 concentrations of gentamicin were tested ranging from 1-1024 micrograms/mL. During the first hour of incubation, there was a marked concentration-dependent kill rate, approximately 3 x 10(3) times in WF and 10(2) times in MH. After the first hour of incubation, the kill rate was independent of the concentration in both media. Our study questions the benefit of the prolonged and high wound concentrations of gentamicin obtained after application of gentamicin-containing PMMA.

Total hip arthroplasty for treatment of canine hip dysplasia

Cemented THA is an established procedure for treating arthropathies of the hip in large, healthy mature dogs. CHD with secondary osteoarthritis is the most common indication. Although comparative studies between THA and excision arthroplasty have not been reported, our experience with both procedures and studies in the literature support THA as the best available treatment for crippling degenerative joint disease secondary to CHD in large, mature dogs. Negative aspects of the procedure include high cost, the potential of significant complications, and the sophisticated surgical technique required. Improvements in patient selection, design of implants, surgical technique, and postoperative care have decreased the incidence of complications and improved the success rate to over 90%. However, concerns in human applications about cement disease and the desire to increase the functional life of the prosthesis have renewed interest in cementless systems. Advantages of cementless THA are fixation via bony ingrowth and avoidance of problems associated with PMMA. Important technical aspects of cementless THA relate to optimal fit and fill so that the prosthesis is stable, bone ingrowth is promoted, and weight-bearing forces are transferred to the proximal femur physiologically. Problems recognized with cementless systems include fissure fracture, bone resorption, and excessive motion between the implant and bone. Currently, investigations are being conducted to develop prosthetic materials that more closely match the stiffness of bone, stem designs that provide optimal fit and maintain normal strain patterns in the bone, and coating materials that promote permanent fixation by bone ingrowth. Early clinical results in humans and research results in dogs have been encouraging but have not withstood the test of time. Results of cementless techniques must be compared to the standards set by cemented THA over the last 20 years in humans and the last 10 years in dogs.

Rapid release of gentamicin from collagen sponge. In vitro comparison with plastic beads

The gentamicin-containing collagen sponge is a new product intended for local application in bone and soft-tissue infections. The release of gentamicin from the collagen sponges was compared in vitro to that from polymethyl-methacrylate (PMMA) beads. A static and kinetic experimental design was used. In the static model, pieces of collagen sponge or PMMA beads were added to 20 mL of distilled water, and during the following hours the gentamicin concentrations in the water were repeatedly measured. This simple model was extended to the kinetic model as the released gentamicin was removed from the water exponentially by means of an infusion-withdrawal pump. The gentamicin was released from the carrier substances with increasing half lives. During the first 4 hours, the half life increased from 0.2 to 1.5 hours for the collagen sponge and from 3 to 78 hours for the PMMA beads. After 1.5 hours, 95 percent of the gentamicin was released from the sponges, whereas only 8 percent was released from the beads.