Superficial Vancomycin Coating of Bone Cement in Orthopedic Revision Surgery: A Safe Technique to Enhance Local Antibiotic Concentrations

Vancomycin Elution Kinetics of Four Antibiotic Carriers Used in Orthopaedic Surgery: In Vitro Study over 42 Days

This study aimed to analyse and compare the vancomycin elution kinetics of four biodegradable, osteoconductive antibiotic carriers used in clinical practice within a 42-day in vitro setting. Carriers A and D already contained vancomycin (1.1 g and 0.247 g), whereas carriers B and C were mixed with vancomycin according to the manufacturer's recommendations (B: 0.83 g and C: 0.305 g). At nine time points, 50% (4.5 mL) of the elution sample was removed and substituted with the same amount of PBS. Probes were analysed with a kinetic microparticle immunoassay. Time-dependent changes in vancomycin concentrations for each carrier and differences between carriers were analysed. Mean initial antibiotic levels were highest for carrier A (37.5 mg/mL) and lowest for carrier B (5.4 mg/mL). We observed time-dependent, strongly negative linear elution kinetics for carriers A (-0.835; p < 0.001), C (-0.793; p < 0.001), and D (-0.853; p < 0.001). Vancomycin concentrations increased from 48 h to 7 d and dropped thereafter in carriers C and D whilst constantly decreasing at any time point for carrier A. Carrier B showed a shallower decrease. Mean antibiotics levels at 42 d were 1.5 mg/mL, 2.6 mg/mL, 0.1 mg/mL, and 0.1 mg/mL for carriers A, B, C, and D. Differences in mean initial and final vancomycin concentrations for carrier A were significantly larger in comparison to C (p = 0.040). A carrier consisting of allogenic bone chips showed the highest vancomycin-to-carrier ratio and the largest elution over the study period. Whilst vancomycin concentrations were still measurable at 42 days for all carriers, carrier A provided a higher drug-to-carrier ratio and a more consistent antibiotic-releasing profile.

Antibacterial intraosseous implant surface coating that responds to changes in the bacterial microenvironment

Bone implant-associated infection is one of the most challenging problems encountered by orthopedic surgeons. There is considerable interest in the development of drug-loaded antibacterial coatings for the surfaces of metal implants. However, it is difficult to achieve the stable local release of an effective drug dose for many antibacterial coatings. In the present study, analyses of the thickness and water contact angle of multiple layers confirmed the successful assembly of multilamellar membrane structures. Measurement of the zone of bacterial inhibition indicated gradual degradation of the (montmorillonite [MMT]/hyaluronic acid [HA])₁₀ multilamellar film structure with concentration-dependent degradation during incubation with hyaluronidase solution and Staphylococcus aureus. In vivo results resembled the in vitro results. Overall, the findings confirm that the (MMT/HA-rifampicin)₁₀ multilamellar film structure exhibits good antibacterial properties and excellent biocompatibility. Further studies of the clinical potential of the antibacterial coating prepared in this experiment are warranted.

Determination of the Elution Capacity of Dalbavancin in Bone Cements: New Alternative for the Treatment of Biofilm-Related Peri-Prosthetic Joint Infections Based on an In Vitro Study

Antibiotic-loaded bone cement is the most widely used approach for the treatment of biofilm-induced septic sequelae in orthopedic surgery. Dalbavancin is a lipoglycopeptide that acts against Gram-positive bacteria and has a long half-life, so we aimed to assess whether it could be a new alternative drug in antibiotic-loaded bone cement for the treatment of periprosthetic joint infections. We assessed the elution capacity of dalbavancin and compared it with that of vancomycin in bone cement. Palacos®R (Heraeus Medical GmbH, Wehrheim, Germany) bone cement was manually mixed with each of the antibiotics studied at 2.5% and 5%. Three cylinders were obtained from each of the mixtures; these were weighed and incubated in 5 mL phosphate-buffered saline at 37°C under shaking for 1 h, 2 h, 4 h, 8 h, 24 h, 48 h, 168 h, and 336 h. PBS was replenished at each time point. The samples were analyzed using high-performance liquid chromatography (vancomycin) and mass cytometry (dalbavancin). Elution was higher than the minimum inhibitory concentration (MIC)90 for both antibiotics after 14 days of study. The release of vancomycin at 14 days was higher than of dalbavancin at each concentration tested (p = 0.05, both). However, the cumulative release of 5% dalbavancin was similar to that of 2.5% vancomycin (p = 0.513). The elution capacity of dalbavancin reached a cumulative concentration similar to that of vancomycin. Moreover, considering that the MIC90 of dalbavancin is one third that of vancomycin (0.06 mg/L and 2 mg/L, respectively) and given the long half-life of dalbavancin, it may be a new alternative for the treatment of biofilm-related periprosthetic infections when loaded in bone cement.

Risk of reinfection after two- or multiple-stage knee revision surgery using superficial vancomycin coating and conventional spacers

This study investigates the effect of superficial vancomycin coating (SVC) in two- or more-stage exchange procedures of prosthetic knee joint infections. We hypothesized that spacer treatment with SVC result in lower reinfection rates than conventional spacers after prosthetic reimplantation. Our secondary aim was to determine the demographic and treatment factors associated with reinfection rates. This retrospective cohort study compromised 96 cases with prosthetic knee infections. Twenty-four cases were treated with a temporary SVC spacer and 72 cases with conventional spacers. Prosthetic reinfection occurred after a median observation period of 1.7 ± 4.0 years in 24 cases (25%). The prevalence of having a reinfection was not significantly different between the two treatment groups (13% [3 cases] in the SVC group vs. 29% [21 cases] in the conventional spacer group [p = .104]). In seven cases (7.3%), two in the SVC group (8.3%) and five (6.9%) in the conventional spacer group (p ≥ .999), histological, respectively microbiological evaluations from the intraoperative specimens revealed persistent infection at the second stage. Nevertheless, in all seven cases no significant higher risk of periprosthetic reinfection was observed during follow-up (p = .750). Our secondary investigation of cofactors revealed that spacers additionally stabilized by nails were significantly associated with a 3.9-fold higher hazard ratio of sustaining a reinfection of revision prosthesis (p = .005).

Comparison of elution characteristics and mechanical properties of acrylic bone cements with and without superficial vancomycin coating (SVC) in the late phase of polymerization

INTRODUCTION

Antibiotic-loaded bone cements (ALBCs) are used as spacers in two-stage revision arthroplasty for periprosthetic joint infection. We previously described a new technique applying vancomycin powder coating to custom-made cements. To our best knowledge, this method of superficial vancomycin coating (SVC) has not been assessed before. We therefore performed an in-vitro study to determine: (1) whether manually applied SVC strengthened the cements' antibiotic effect; and (2) whether the mechanical requirements for the cements were fulfilled.

HYPOTHESIS

SVC increases the antibiotic effect of cement within the first 24hours.

METHODS

Cuboid blocks were produced from two commercially available acrylic ALBCs (Palacos R+G and Copal G+V) with and without SVC. Each block was eluted in phosphate-buffered saline at 37°C. Eluates obtained at 1, 2, 3, 4, 5, 10, 15, 30 and 60minutes and 3, 6 and 24hours were evaluated against Staphylococcus aureus (Palacos, Copal) and methicillin-resistant Staphylococcus aureus (MRSA) (Copal) using zone of inhibition tests. Mechanical test results (bending modulus, bending strength) were compared to ISO requirements (≥1800MPa, ≥50MPa).

RESULTS

Palacos with SVC produced significantly greater zones of inhibition against Staphylococcus aureus than Palacos without SVC (p=0.002). Copal with SVC showed greater zones of inhibition against both Staphylococcus aureus and MRSA (p=0.002). The antibiotic effect was enhanced by SVC in both cements at every time point within 24hours. The bending modulus and bending strength of Palacos with SVC (2089±166MPa, 60.8±2.6 MPA) and Copal with SVC (2283±195MPa, 56.9±2.4MPa) were significantly above ISO requirements.

CONCLUSION

SVC boosts the antibiotic effect of ALBCs in the first 24hours, while maintaining sufficient stability. These findings endorse SVC as a promising additive in septic revision surgery.

LEVEL OF EVIDENCE

III; case control study.

Analysis of Culture Positive First and Second Stage Procedures in Periprosthetic Knee and Hip Joint Infections

BACKGROUND

A positive microbiological result at reimplantation may lead to a failed 2-stage revision arthroplasty in the treatment of periprosthetic joint infections. Little is known about changes in microbiological spectrum and resistance pattern between culture positive first and second stage procedures in revision knee and hip arthroplasty.

METHODS

Between January 2011 and December 2019, we performed 327 two-stage revision arthroplasties on 312 patients. There were 37 of 312 (11.9%) patients (20 hips/17 knees) who had a positive microbiological culture during the first and second stage procedure. We analyzed the microbiological spectrum, antimicrobial resistance pattern, and clinical outcome of culture positive first and second stage procedures as well as subsequent re-revisions.

RESULTS

Re-revision was necessary in 40.5% (15/37) of patients with culture positive first and second stage procedure at a median follow-up of 3.5 years. We found microbiological changes in 83.8% (31/37) of patients between the first and second stage and in 88.9% (8/9) between the second stage and subsequent culture positive re-revision. Polymicrobial infections were found in 21.6% (8/37) of first and in 16.2% (6/37) of second stage procedures. In 27% (10/37) of patients, microorganisms persisted between the first and second stage procedure. The antimicrobial resistance pattern changed in 60% of persistent microorganisms between the first and second stage procedure.

CONCLUSION

Changes in microbiological spectrum and resistance pattern are common between culture positive first and second stage procedures as well as subsequent re-revisions. This has to be considered in the antimicrobial treatment of periprosthetic joint infections.

[Manual addition of antibiotics to industrial bone cement mixes : Investigations of the dry mix in the cement cartridge during manual admixture to polymer-active substance mixtures]

BACKGROUND

Periprosthetic infection (PPI) is a rare but serious complication. An elementary component of the therapy of PPI is the use of bone cement with the addition of antibiotics. For targeted therapy, manual mixing of antibiotics with industrially produced bone cement mixtures is often necessary. Possible problems resulting from manual mixing have not been described sufficiently so far.

OBJECTIVES

Therefore, the aim of the present study was to describe the influence of the additional homogenisation by dry mixing of a polymer-active substance mixture on the quality of manually added cement.

MATERIAL AND METHODS

In the laboratory-based study, four cement samples were prepared using different methods for manual addition and homogenisation of antibiotics (vancomycin). The reference control was Copal® G + V (Heraeus Medical GmbH, Wehrheim, Germany), to which the vancomycin (V) had already been industrially added. The samples were then examined for mechanical, microbiological and microscopic parameters.

RESULTS

In the mechanical and microbiological results, no statistically significant differences were found between the manually added mixtures and the reference. After dry mixing of the polymer powder, the inner surface of the mixing cartridges used showed signs of scratching in the microscopic examination and showed indications of abrasion during mixing.

CONCLUSION

The manual addition of antibiotics to industrially produced bone cement should be reserved for selected indications if the bone cement mixtures produced by industry are not sufficient.

High rate of infection eradication following cementless one-stage revision hip arthroplasty with an antibacterial hydrogel coating

PURPOSE

We conducted a retrospective study to evaluate the outcomes of one-stage revision total hip arthroplasty (THA) following periprosthetic joint infection (PJI) in terms of eradication of the infection, improvement of pain and joint function. We hypothesized that this treatment strategy could lead to satisfying results in selected patients after preoperative microorganism isolation.

METHODS

Ten patients underwent cementless one-stage revision hip arthroplasty with antibacterial hydrogel coating for the treatment of an infected THA. Inclusion criteria were: the presence of a known organism with known sensitivity, patients non-immunocompromised with healthy soft tissues with minimal or moderate bone loss. Mean age at surgery was 69.4 years. Assessment included objective examination, Harris hip score, visual analog scale pain score, standard X-rays.

RESULTS

At a mean follow-up of 3.1 years (range, 2-5 years), none of the patients had clinical or radiographic signs suggesting recurrent infection. Follow-up examination showed significant improvement of all variables compared to pre-operative values (p < 0.05). Radiographs did not show progressive radiolucent lines or change in the position of the implant.

CONCLUSIONS

One-stage revision THA with antibacterial hydrogel coated implants represents a safe and effective procedure providing infection eradication and satisfying subjective functional outcomes in selected patients.

Toxic Effect of Vancomycin on Viability and Functionality of Different Cells Involved in Tissue Regeneration

To prevent infections local delivery of antibiotics is a useful tool. Especially in bone fractures, vancomycin impregnated bone cements are often used allowing high concentrations of antibiotics at the infection side without high serum concentrations. However, besides potential pathogens, cells involved in tissue regeneration may also be affected by the drug. We investigated the effect of vancomycin on the viability and functionality on osteoblasts, endothelial cells, fibroblasts and skeletal muscle cells. Our results show that the viability of all cells analyzed was reduced by vancomycin and that the observed effects were time and concentration dependent. The most pronounced toxic effect was detected on day three when even the lowest concentration of 0.01 mg/ml led to a significant decrease in proliferation compared to control. Functionality assays of osteoblasts and skeletal muscle cells revealed a sensitive reaction of the cells to the drug, indicating that vancomycin is toxic to these cells during the process of differentiation. These data suggest that the vancomycin administration is critical for cell survival and function. Therefore, the concentration of administered antibiotics needs to be carefully evaluated to find a balance between defense against pathogens and functionality of host cells and tissues.

Systematic Review and Meta-Analysis of Intrawound Vancomycin in Total Hip and Total Knee Arthroplasty: A Call for a Prospective Randomized Trial

BACKGROUND

Topical intrawound vancomycin has been used extensively in spine surgery to decrease surgical site infections. However, the efficacy of intrawound vancomycin in total hip (THA) and total knee arthroplasty (TKA) to prevent periprosthetic joint infection (PJI) has not been established.

METHODS

The PubMed and MEDLINE databases were searched to identify studies utilizing intrawound vancomycin in primary and revision THA and TKA. Data for postoperative infection were pooled using random effect models with results reported as odds ratios (ORs) and 95% confidence intervals. Studies were weighted by the inverse variance of their effect estimates.

RESULTS

Of the 91 studies identified, 6 low-quality retrospective studies (level III) were pooled for further analysis. A total of 3298 patients were assessed, 1801 of which were treated with intrawound vancomycin. Overall, patients who received vancomycin had a decreased rate of PJI (OR 0.2530, P < .0001). When analyzed separately, TKA patients and THA patients who received intrawound vancomycin had lower rates of PJI (OR 0.3467, P = .0005 and OR 0.3672, P = .0072, respectively). Pooled primary TKA and THA patients receiving vancomycin saw the rate of PJI decrease (OR 0.4435, P = .0046). Pooled revision TKA and THA patients saw a similar decrease in infection rates (OR 0.2818, P = .0013). No apparent publication bias was observed; however, the results from this analysis are limited by the low quality of evidence and inherent potential for bias.

CONCLUSION

Intrawound vancomycin may reduce the risk of PJI in primary and revision TKA and THA. However, only low-quality evidence exists, highlighting the need for randomized controlled trials before broad adoption of this practice can be recommended given the potential implications of widespread use of vancomycin in hip and knee arthroplasty.

Two-stage cementless hip revision for peri-prosthetic infection with an antibacterial hydrogel coating: results of a comparative series

PURPOSE

The aim of this study was to investigate the hypothesis that a two-stage exchange procedure, performed with an antibiotic-loaded, fast-resorbable hydrogel coating, may provide better infection cure rate than a two-stage procedure without the coating, in patients affected by peri-prosthetic hip infection.

METHODS

In this case-control study, 27 patients, treated with a two-stage procedure, using cementless implants coated with an antibiotic-loaded hydrogel (DAC®, "Defensive Antibacterial Coating"), were compared with 27 matched controls, treated with a two-stage cementless revision procedure, without the coating.

RESULTS

At a mean follow-up of 2.7 (minimum 2.1-maximum 3.5) years, no evidence of infection, implant loosening, or adverse events were observed in the DAC-treated group, compared to four cases of infection recurrence in the control group.

CONCLUSIONS

Although in a relatively limited series of patients our data show that cementless two-stage hip revision, performed with an antibacterial hydrogel coating, may provide better infection control than two-stage without the coating, with reduced hospitalization time, these findings warrant further studies in the possible applications of antibacterial coating technologies to treat implant-related infections.

[Local antibiotic therapy]

The treatment of superficial wound infections with local antibiotics is considered to be problematic as it is accompanied by an increased risk of resistance development and ineffectiveness in deeper regions. On the contrary, the local application of antibiotics is useful in arthroplasty and necessary if implants are utilized. The reason for this is the prevention of a rapid biofilm formation on foreign implants and a resulting infection may remain undiscovered until it becomes chronic. Apart from exogenous material, necrotic tissue (e. g. bone sequestra) provides suitable retreat areas for pathogens in the body. Because of the characteristics of bone and joint infections and an exceptional infection recurrence rate, a combined approach is required. Systemic antibiotic prophylaxis is able to reduce the number of pathogens acquired by perioperative contamination or hematogenic spread from another focus of infection; however, systemically applied antibiotics often fail to form an effective colonization barrier around the implant because their ability to penetrate the bone is relatively low. On the other hand, the high concentration of locally released antibiotics leads to an effective protection of the implant from bacteria in situ. Thus, for the treatment of implant-associated infections, systemic and local application of anti-infective agents is a reliable adjuvant measure that improves the therapeutic success. Polymethylmethacrylate (PMMA) bone cement is the most commonly used local drug carrier. Based on clinical and microbiological results, microbiologists and infectious disease experts together with the surgeon and pharmacist determine which anti-infective agents are indicated for systemic and local, PMMA cement-related application. Because there is no evident concept for the local application, unlike the recommendation for systemic use of anti-infective agents, this review article describes which aspects should be taken into account.