Elution profiles of tobramycin and vancomycin from high-purity calcium sulphate beads incubated in a range of simulated body fluids

Antibiotic calcium sulphate beads lower the bacterial burden and prevent infection in a mouse model of periprosthetic joint infection

Aims

Delayed postoperative inoculation of orthopaedic implants with persistent wound drainage or bacterial seeding of a haematoma can result in periprosthetic joint infection (PJI). The aim of this in vivo study was to compare the efficacy of vancomycin powder with vancomycin-eluting calcium sulphate beads in preventing PJI due to delayed inoculation.

Methods

A mouse model of PJI of the knee was used. Mice were randomized into groups with intervention at the time of surgery (postoperative day (POD) 0): a sterile control (SC; n = 6); infected control (IC; n = 15); systemic vancomycin (SV; n = 9); vancomycin powder (VP; n = 21); and vancomycin bead (VB; n = 19) groups. Delayed inoculation was introduced during an arthrotomy on POD 7 with 1 × 105 colony-forming units (CFUs) of a bioluminescent strain of Staphylococcus aureus. The bacterial burden was monitored using bioluminescence in vivo. All mice were killed on POD 21. Implants and soft-tissue were harvested and sonicated for analysis of the CFUs.

Results

The mean in vivo bioluminescence in the VB group was significantly lower on POD 8 and POD 10 compared with the other groups. There was a significant 1.3-log10 (95%) and 1.5-log10 (97%) reduction in mean soft-tissue CFUs in the VB group compared with the VP and IC groups (3.6 × 103 vs 7.0 × 104; p = 0.022; 3.6 × 103 vs 1.0 × 105; p = 0.007, respectively) at POD 21. There was a significant 1.6-log10 (98%) reduction in mean implant CFUs in the VB group compared with the IC group (1.3 × 100 vs 4.7 × 101, respectively; p = 0.038). Combined soft-tissue and implant infection was prevented in 10 of 19 mice (53%) in the VB group as opposed to 5 of 21 (24%) in the VP group, 3 of 15 (20%) in the IC group, and 0% in the SV group.

Conclusion

In our in vivo mouse model, antibiotic-releasing calcium sulphate beads appeared to outperform vancomycin powder alone in lowering the bacterial burden and preventing soft-tissue and implant infections.

Debridement-Reconstruction-Docking Management System Versus Ilizarov Technique for Lower-Extremity Osteomyelitis

BACKGROUND

Osteomyelitis causes marked disability and is one of the most challenging diseases for orthopaedists to treat because of the considerable rate of infection recurrence. In this study, we proposed and assessed the debridement-reconstruction-docking (DRD) system for the treatment of lower-extremity osteomyelitis. This procedure comprises 3 surgical stages and 2 preoperative assessments; namely, pre-debridement assessment, debridement, pre-reconstruction assessment, reconstruction, and docking-site management. We evaluated the use of the DRD system compared with the Ilizarov technique, which is defined as a 1-stage debridement, osteotomy, and bone transport.

METHODS

This retrospective cohort included 289 patients who underwent either DRD or the Ilizarov technique for the treatment of lower-extremity osteomyelitis at a single institution between January 2013 and February 2021 and who met the eligibility criteria. The primary outcome was the rate of infection recurrence. Secondary outcomes included the external fixator index (EFI), refracture rate, and the Paley classification for osseous and functional results. An inverse-probability-weighted regression adjustment model was utilized to estimate the effect of the DRD system and Ilizarov technique on the treatment of lower-extremity osteomyelitis.

RESULTS

A total of 131 and 158 patients underwent DRD or the Ilizarov technique, respectively. The inverse-probability-weighted regression adjustment model suggested that DRD was associated with a significant reduction in infection recurrence (risk ratio [RR], 0.26; 95% confidence interval [CI], 0.13 to 0.50; p < 0.001) and EFI (-6.9 days/cm, 95% CI; -8.3 to -5.5; p < 0.001). Patients in the DRD group had better Paley functional results than those in the Ilizarov group (ridit score, 0.55 versus 0.45; p < 0.001). There was no significant difference between the 2 groups in the rate of refracture (RR, 0.87; 95% CI, 0.42 to 1.79; p = 0.71) and Paley osseous results (ridit score, 0.51 versus 0.49; p = 0.39).

CONCLUSIONS

In this balanced retrospective cohort of patients with lower-extremity osteomyelitis, the use of the DRD system was associated with a reduced rate of infection recurrence, a lower EFI, and better Paley functional results compared with the use of the Ilizarov technique.

LEVEL OF EVIDENCE

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

Hydrogel Coating versus Calcium Sulphate Beads as a Local Antibiotic Carrier for Debridement Procedures in Acute Periprosthetic Joint Infection: A Preliminary Study

Periprosthetic joint infections (PJI) are among the most difficult complications to treat in orthopaedic surgery. Debridement, antibiotics, and implant retention (DAIR) represent an efficient strategy for acute PJI, especially when resorbable local antibiotic carriers and coatings are used. The aim of this pilot study was to evaluate the difference between using antibiotic-loaded hydrogel (ALH) and calcium sulphate (CS) beads in the DAIR procedure. We analysed 16 patients who had been treated since 2018 for acute PJI, namely eight patients with knee PJI (50%), seven with hip PJI (43.7%), and one with shoulder PJI (6.2%). Nine patients were treated with the Debridement, Antibiotic Coating and Retention of the Implant (DACRI) method, while seven were treated with the Debridement, Antibiotic Pearls, Retention of the Implant (DAPRI) method. We found no significant differences between the two groups in terms of age, sex, the American Society of Anesthesiologists risk score, Charlson Comorbidity Index, localisation, days from onset to diagnosis and pathogenesis. Furthermore, no differences were found between the DACRI and DAPRI groups in terms of infection control (15 patients, 93.75% with p = 0.36) and last C-Reactive Protein values (p = 0.26), with a mean follow-up of 26.1 ± 7.7 months. Treatment for one patient affected by knee Candida albicans PJI in the DACRI group was not successful. In conclusion, DAPRI and DACRI appear to be safe and effective treatments for PJIs. This evidence will encourage the development of new clinical research into local carriers and coatings for use in acute implant-associated infections.

Mid-Term Results of Single-Stage Surgery for Patients with Chronic Osteomyelitis Using Antibiotic-Loaded Resorbable PerOssal® Beads

This retrospective study reports on the treatment of chronic osteomyelitis with local debridement combined with PerOssal^®. The diagnosis of chronic osteomyelitis was confirmed in all cases and classified according to the Cierny-Mader (C-M) classification. The primary outcome was the eradication of infection at a minimum of one year after surgery. A total of 93 patients (median age: 40 years) were included. The most represented sites were the femur (24, 25.8%) and tibia (52, 55.9%). Twenty-six patients (28.0%) had significant local or systemic comorbidities (C-M Class B hosts). According to anatomic type, 31 cases were type I, 13 type II, 21 type III and 28 type IV. Vancomycin was added to PerOssal^® in most cases (80, 86.0%). In 24 (25.8%) cases, Vancomycin and Rifampicin were combined. In 32 (34.4%) cases, intraoperative cultures were negative. Staphylococcus aureus was isolated in 39 (63.9%) patients, and Gram-negative bacteria were isolated in 12 cases. The median follow-up was 21 months (range 12-84). A total of 21 (22.6%) patients developed an infection recurrence (IR) after a median follow-up of 11 months (range: 1-47). PerOssal^® holds several practical advantages compared to other bone void fillers. Thus, due to its good biocompatibility and sufficient antibiotic release, it represents a viable adjuvant treatment in chronic osteomyelitis.

Implant retention with serial debridement and use of antibiotic-loaded calcium sulfate beads in acute fracture-related infection (FRI) after pelvic ring or acetabular fractures: A retrospective case series of 7 cases

BACKGROUND

The development of a pelvic wound infection in the presence of hardware after open reduction and internal fixation presents a clinical dilemma and there is little literature to aid in decision-making. The purpose of this study was to describe the possibility of debridement, antibiotic pearls and retention of the implant (DAPRI) procedure to eradicate the infection.

METHODS

Tumor-like debridement, antibiotic pearls and retention of the implant (DAPRI) aimed to remove the biofilm allowing a higher and prolonged local antibiotic concentration by using calcium sulfate antibiotic-added beads. Wound status, radiological signs of bone healing, gait and functional activity of the patient were evaluated.

RESULTS

Seven patients underwent this technique. The mean follow up time was nine months (range: 6 -16 months). Complete wound healing was achieved in all the patients with no major complications. Average time of bony union was 4.3 months (range: 3-6 months) with no need for implant removal.

CONCLUSION

The DAPRI technique might represent a safe and more conservative treatment for management of early fracture-related infections (FRI) of the pelvis and acetabulum.

An assessment of physical properties and the viability of osteoblast-like cells of cefazolin-impregnated calcium sulfate bone-void filler

Calcium sulfate, an injectable and biodegradable bone-void filler, is widely used in orthopedic surgery. Based on clinical experience, bone-defect substitutes can also serve as vehicles for the delivery of drugs, for example, antibiotics, to prevent or to treat infections such as osteomyelitis. However, antibiotic additions change the characteristics of calcium sulfate cement. Moreover, high-dose antibiotics may also be toxic to bony tissues. Accordingly, cefazolin at varying weight ratios was added to calcium sulfate samples and characterized in vitro. The results revealed that cefazolin changed the hydration reaction and prolonged the initial setting times of calcium sulfate bone cement. For the crystalline structure identification, X-ray diffractometer revealed that cefazolin additive resulted in the decrease of peak intensity corresponding to calcium sulfate dihydrate which implying incomplete phase conversion of calcium sulfate hemihydrate. In addition, scanning electron microscope inspection exhibited cefazolin changed the morphology and size of the crystals greatly. A relatively higher amount of cefazolin additive caused a faster degradation and a lower compressive strength of calcium sulfate compared with those of uploaded samples. Furthermore, the extract of cefazolin-impregnated calcium sulfate impaired cell viability, and caused the death of osteoblast-like cells. The results of this study revealed that the cefazolin additives prolonged setting time, impaired mechanical strength, accelerated degradation, and caused cytotoxicity of the calcium sulfate bone-void filler. The aforementioned concerns should be considered during intra-operative applications.

Is the routine use of local antibiotics in the management of periprosthetic joint infections justified?

Periprosthetic joint infection (PJI) following total hip and total knee arthroplasty continues to be a leading cause of re-operation and revision arthroplasty. Not only is the treatment of PJI notoriously challenging, but success rates are variable. Regardless of the surgical strategy used, successful management of PJI requires a comprehensive surgical debridement focused at eradicating the underlying biofilm followed by appropriate antimicrobial therapy. Although systemic antimicrobial delivery continues to be a cornerstone in the treatment of PJI, many surgeons have started using local antibiotics to deliver higher concentrations of antibiotics directly into the vulnerable joint and adjacent soft tissues, which often have compromised vascularity. Available evidence on the use of topical powder, bone cement, and calcium sulphate carriers for local delivery of antibiotics during the initial treatment of PJI is limited to studies that are extremely heterogeneous. There is currently no level-1 evidence to support routinely using these products. Further, appropriately powered, prospective studies are needed to quantify the safety and efficacy of antibiotic-located calcium-sulphate carriers to justify their added costs. These products should not encourage surgeons to deviate from best practice guidelines, such as those recommended during the International Consensus Meeting on Musculoskeletal Infections.

Assessing tobramycin levels and renal function following the implantation of CaSO4 beads impregnated with tobramycin: A prospective cohort study

This study aimed to evaluate the risk of serum tobramycin concentrations exceeding therapeutic levels after administration of calcium sulfate (CaSO4) beads containing either 240 mg or 400 mg tobramycin and 1000 mg vancomycin. This single-center, prospective. This single-center, prospective study included included Piedmont Columbus, Regional orthopedic surgery patients. Following the implantation of tobramycin into CaSO4 beads, serially measured serum tobramycin concentrations were evaluated after 6, 12, 24, and 48 hours. In addition to that, serum tobramycin concentration was evaluated after 5 days. None of the patients who received 240 mg tobramycin-impregnated beads had a tobramycin level >2 μg/mL. Six hours after implantation, the tobramycin level in 2 out of 2 (100%) patients who received 400 mg of tobramycin-impregnated beads was >2 μg/mL. One day following the surgery, the median serum creatinine was 0.85 mg/dL, with an interquartile range of 0.73 to 1.04 mg/dL. No cases of acute kidney injury were observed. This cohort demonstrated that non-nephrotoxic serum tobramycin levels could be achieved in CaSO4 beads mixed with 240 mg or 400 mg of tobramycin.

Identifying alternative antibiotics that elute from calcium sulfate beads for treatment of orthopedic infections

There has been increasing interest in the use of a synthetic absorbable calcium sulfate (CaSO₄ ) for local antibiotic delivery in orthopaedic infections. The purpose of this study was to quantify elution kinetics of six antibiotics (amikacin, meropenem, fosfomycin, minocycline, cefazolin, and dalbavancin) from a clinically relevant CaSO₄ bead model and compare elution and antimicrobial activity to the current clinical gold standards: vancomycin and tobramycin. Antibiotic-loaded synthetic CaSO₄ beads were immersed in phosphate buffered saline and incubated at 37°C. Eluent was harvested at eight time points over 28 days. Antibiotic concentrations were measured by high performance liquid chromatography to quantify elution rates. CaSO₄ beads demonstrated burst release kinetics. Dalbavancin, cefazolin, and minocycline all demonstrated similar elution profiles to vancomycin. Amikacin and meropenem demonstrated favorable elution profiles and durations of above-minimum inhibitory concentration when compared to tobramycin. Clinical Significance: This study provides important novel data regarding the utility of amikacin, meropenem and dalbavancin as alternative choices to place in CaSO₄ carriers when treating orthopaedic infections.

Profound Hypercalcemia Associated with Acute Toxic-Metabolic Encephalopathy After Calcium Sulfate Bead Use: A Case Report

CASE

We present the case of an 81-year-old woman who developed profound hypercalcemia requiring admission to the intensive care unit after calcium sulfate bead use during revision hip arthroplasty. The patient's serum calcium level peaked at 21.0 mg/dL and was associated with acute encephalopathy. After treatment with calcitonin and bisphosphonates, her serum calcium level normalized and her mentation improved.

CONCLUSION

The risk of clinically significant hypercalcemia should be considered when using calcium sulfate during orthopaedic surgery.

Antibiotic-Impregnated Calcium Sulfate vs. Wound Irrigation-Suction to Treat Chronic Calcaneal Osteomyelitis

BACKGROUND

Chronic osteomyelitis of calcaneus is not rare but is very hard to treat. Irrigation-suction and antibiotic-impregnated calcium sulfate following debridement are commonly used in managing chronic osteomyelitis, but their effects have rarely been compared. We aimed to compare the effectiveness of antibiotic-impregnated calcium sulfate with irrigation-suction in the treatment of patients with chronic calcaneal osteomyelitis.

METHODS

From January 2011 to June 2018, adult patients at our institute with chronic osteomyelitis receiving treatment of either antibiotic-impregnated calcium sulfate (CS group) or irrigation-suction (IS group) following thorough debridement were screened and selected according to the inclusion and exclusion criteria. The clinical presentation, laboratory tests, complications, and the ultimate single-staged cure rate and recurrence were compared.

RESULTS

A total of 61 patients, including 41 in the CS group and 20 in the IS group, were included in our study. Of the patients, 85.4% in the CS group and 60.0% in the IS group (P = .006) were successfully cured in the single stage, respectively, without infection recurrence. Lower infection recurrence rates with shorter hospital stay were found in the CS group than the IS group. Inflammatory biomarkers after surgery with both treatments were slightly decreased and not significantly different from preoperative or between-groups postoperative. Exudate from incision was found primarily in the CS group.

CONCLUSION

This study demonstrates that both antibiotic-impregnated calcium sulfate and irrigation-suction after careful and thorough surgical debridement are generally effective in treating chronic calcaneal osteomyelitis. Antibiotic-impregnated calcium sulfate achieved a higher single-staged cure rate but was associated with an increased postoperative wound exudate.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Rare Causes of Hypercalcemia

This article discusses rare causes of hypercalcemia. Hypercalcemia can rarely be associated with immobilization, genetic diseases in children such as Williams-Beuren syndrome, Hypophosphatasia, Jansen Metaphyseal Chondrodysplasia (JMC), cosmetic injection, milk-alkali syndrome (MAS), calcium sulfate beads administration, manganese intoxication, postacute kidney failure recovery, and Paget's disease.

Wound Leakage With the Use of Calcium Sulphate Beads in Prosthetic Joint Surgeries: A Systematic Review

Since its first use as a bone void filler at the end of the 19th century, calcium sulphate products have been adapted in different ways to aid orthopaedic surgeons. Calcium sulphate local antibiotic delivery systems offer a promising solution in the delivery of high antibiotic concentrations locally for an extended period of time. Over the years, multiple centres have reported side effects such as wound drainage, heterotrophic ossification and hypercalcaemia. This study was carried out to assess the risk of wound drainage in prosthetic joints after implantation of antibiotic-impregnated calcium sulphate beads. Two reviewers searched the literature in three online databases using the Cochrane methodology for systematic reviews. The search of databases yielded 182 articles. The studies without reported post-operative complications, mainly drainage outcomes, were excluded. After screening, seven articles were deemed suitable and selected. Out of the 1,112 cases identified, 43 joints developed wound drainage after calcium sulphate bead placement. This complication was resolved in all these cases by either conservative or operative approaches. The factors implicated in the development of wound drainage include the volume of the product used, procedural placement and host factors. The result of this systematic review shows that calcium sulphate products can be used for treatment and prophylaxis in prosthetic joints with a risk of post-procedural wound drainage. This risk, however, is lesser with the use of synthetic calcium sulphate products as compared with conventional calcium sulphate products.

Gelatin Methacryloyl Hydrogels for the Localized Delivery of Cefazolin

The tuneability of hydrogels renders them promising candidates for local drug delivery to prevent and treat local surgical site infection (SSI) while avoiding the systemic side-effects of intravenous antibiotic injections. Here, we present a newly developed gelatin methacryloyl (GelMA)-based hydrogel drug delivery system (GelMA-DDS) to locally deliver the broad-spectrum antibiotic cefazolin for SSI prophylaxis and treatment. Antibiotic doses from 3 µg to 90 µg were loaded in photocrosslinked GelMA hydrogel discs with 5 to 15% w/v polymer concentration and drug encapsulation efficiencies, mechanical properties, crosslinking and release kinetics, as well as bacterial growth inhibition were assessed. Our results demonstrate that all GelMA groups supported excellent drug encapsulation efficiencies of up to 99%. Mechanical properties of the GelMA-DDS were highly tuneable and unaffected by the loading of small to medium doses of cefazolin. The diffusive and the proteolytic in vitro drug delivery of all investigated cefazolin doses was characterized by a burst release, and the delivered cefazolin amount was directly proportional to the encapsulated dose. Accelerated enzymatic degradation of the GelMA-DDS followed zero-order kinetics and was dependent on both the cefazolin dose and GelMA concentration (3-13 h). Finally, we demonstrate that cefazolin delivered from GelMA induced a dose-dependent antibacterial efficacy against S. aureus, in both a broth and a diffusive assay. The cefazolin-loaded GelMA-DDS presented here provides a highly tuneable and easy-to-use local delivery system for the prophylaxis and treatment of SSI.

Elution Kinetics from Antibiotic-Loaded Calcium Sulfate Beads, Antibiotic-Loaded Polymethacrylate Spacers, and a Powdered Antibiotic Bolus for Surgical Site Infections in a Novel In Vitro Draining Knee Model

Antibiotic-tolerant bacterial biofilms are notorious in causing PJI. Antibiotic loaded calcium sulfate bead (CSB) bone void fillers and PMMA cement and powdered vancomycin (VP) have been used to achieve high local antibiotic concentrations; however, the effect of drainage on concentration is poorly understood. We designed an in vitro flow reactor which provides post-surgical drainage rates after knee revision surgery to determine antibiotic concentration profiles. Tobramycin and vancomycin concentrations were determined using LCMS, zones of inhibition confirmed potency and the area under the concentration-time curve (AUC) at various time points was used to compare applications. Concentrations of antibiotcs from the PMMA and CSB initially increased then decreased before increasing after 2 to 3 h, correlating with decreased drainage, demonstrating that concentration was controlled by both release and flow rates. VP achieved the greatest AUC after 2 h, but rapidly dropped below inhibitory levels. CSB combined with PMMA achieved the greatest AUC after 2 h. The combination of PMMA and CSB may present an effective combination for killing biofilm bacteria; however, cytotoxicity and appropriate antibiotic stewardship should be considered. The model may be useful in comparing antibiotic concentration profiles when varying fluid exchange is important. However, further studies are required to assess its utility for predicting clinical efficacy.

One-stage debridement and bone transport versus first-stage debridement and second-stage bone transport for the management of lower limb post-traumatic osteomyelitis

Background

Treatment of lower limb post-traumatic osteomyelitis used to be a staged process, with radical debridement of bone and soft tissues at first stage, followed by a second-stage limb reconstruction operation to restore the limb integrity. Some studies recently reported that achieving infection eradication and limb reconstruction at single-stage seems to be an effective method for lower limb infection, but a comparative study remains lacking. This study aims to compare the results of radical debridement combined with a first/second-staged osteotomy and bone transport, for the management of lower limb post-traumatic osteomyelitis.

Methods

From January 2013 to June 2018, a total of 102 patients with lower limb post-traumatic osteomyelitis met the criteria were included for analysis, in which 70 patients received one-stage debridement, antibiotic-loaded implantation, metaphysis osteotomy and bone transport were named as one-stage group, while 32 patients with first-stage debridement and antibiotic-loaded calcium sulfate implantation, second-stage osteotomy and bone transport were devised as two-stage group. The outcomes of hospitalization (hospital stay, costs of treatment, surgical time, antibiotic usage) and follow-up (infection-free, treatment failure, infection recurrence, external fixation index (EFI) and docking site union) between the two groups were retrospectively compared.

Results

For outcomes of hospitalization, patients in the one-stage group had batter results on hospital stay (18.2 days versus 28.9 days, P ​< ​0.05), surgical time (164.8 ​min versus 257.4 ​min, P ​< ​0.05), cost of treatment (¥101726.1 versus ¥126718.8, P ​< ​0.05) and the course of antibiotic usage (10.3 days versus 12.0 days, P ​< ​0.05). During the follow-up, 87.1% (61/70) patients in the one-stage group compared to 93.8% (30/32) patients in the two-stage group achieved infection-free (P ​> ​0.05) without any additional debridement operation. 94.3% (66/70) patients in the one-stage group earned wound healing after the operation, comparing to 96.9% (31/32) patients healed in the two-stage group (P ​> ​0.05). Uncontrolled infection was observed on 4 (5.7%) patients in the one-stage group and 1 (3.1%) patients in the two-stage group (P ​> ​0.05), with a result of three achieved infection free in the one-stage group and one patient suffered from amputation in each group respectively. 5 (7.2%) patients in the one-stage group and 1 (3.2%) patient in the two-stage group encountered with infection recurrence (P ​> ​0.05) and were well-managed with re-debridement and antibiotics usage. Significance was not found between two groups on EFI (74.8 days/cm versus 69.0 days/cm, P ​> ​0.05) and docking site nonunion rate (14.5% versus 18.9%, P ​> ​0.05), indicating that bone transport in different stages played a less essential role on bone generation process. The other complications, such as prolonged aseptic drainage [24.3% (17/70) versus 21.9% (7/32)], re-fracture [5.8% (4/69) versus 3.2% (1/31)], pin-tract infection [23.2% (16/69) versus 19.4% (6/31)], joint stiffness and deformity [26.1% (18/69) versus 32.3% (10/31)], also showed less significance when comparing between two groups (P ​> ​0.05), suggesting that different transport stages play little role on complications formation.

Conclusions

One-stage radical debridement and bone transport was proven to be a safe and effective method for treating static (or near static) lower limb osteomyelitis.

Translational potential statement

Translational potential statement One-stage debridement and bone transport is sample, effective and time-saving, with similar complications compared to conventional two-stage protocol. This treatment protocol might provide an alternative for the treatment of static (or near static) lower limb osteomyelitis.

Debridement, antibiotic pearls, and retention of the implant in the treatment of infected total hip arthroplasty

In this article the authors describe a modified surgical technique developed to enhance the classical irrigation and debridement procedure to improve the possibilities of retaining a total hip arthroplasty (THA) undergoing acute periprosthetic joint infection (PJI). This technique, debridement antibiotic pearls and retention of the implant (DAPRI), aims to remove the intra-articular biofilm allowing a higher and prolonged local antibiotic concentration by using calcium sulphate antibiotic-added beads. The combination of 3 different surgical techniques (tumour-like synovectomy, Argon Beam application and chlorhexidine gluconate brushing) might enhance the disruption and removal of the bacterial biofilm which is the main responsible of antibiotics and antibodies resistance. The timing of the diagnosis (6 weeks from the original surgery or 1 week from clinical symptoms appearance in the case of an hematogenous infection) and the preoperative isolation of the germ are fundamental in order to obtain a satisfactory outcome. A 12-week course of postoperative antibiotic therapy (6 weeks I.V. and 6 weeks oral) complete the postoperative protocol used by the authors.The DAPRI technique might represent a safe and more conservative treatment for acute and early hematogenous PJI.

Extensive eggshell-like debridement technique plus antibiotic-loaded calcium sulphate for one-stage treatment of chronic calcaneal osteomyelitis

BACKGROUND

Management of chronic calcaneal osteomyelitis is challenging. At present, there is still no widely accepted, simple, and effective surgical method to eradicate the infection and prevent osteomyelitis recurrence. The objective of this study was to assess the outcomes of one-stage treatment of chronic calcaneal osteomyelitis with a shape-preserving debridement technique combined with antibiotic-loaded calcium sulphate.

METHODS

Between 2012 and 2018, 33 patients (33 limbs) with chronic calcaneal osteomyelitis were treated with a novel debridement technique, named "eggshell-like debridement", plus antibiotic-impregnated calcium sulphate. The infection remission rate, recurrence rate, and amputation rate were analyzed. The American Orthopedic Foot and Ankle Society (AOFAS) ankle and hindfoot score was used to assess postoperative hindfoot function.

RESULTS

26 patients (81.8%) achieved infection remission without recurrence. In the patients with osteomyelitis remission, pain, limitation of movement, sinus tracts, and typical redness and swelling were generally eliminated. Most of the patients could tolerate full weight-bearing without pain. The average AOFAS ankle and hindfoot score was 88 points (range, 67-100 points), implying the foot function was mostly restored. 6 patients (18.2%) had osteomyelitis recurrence but no amputation was required to elimilate the infection.

CONCLUSIONS

Eggshell-like debridement combined with antibiotic-loaded calcium sulphate is an effective method for one-stage management of chronic calcaneal osteomyelitis. With the application of this technique, secondary autogenous bone or muscle flap grafts are unnecessary. The surgical procedure can be simplified whlie the hindfoot function is well preserved.

Prevention and Killing Efficacy of Carbapenem Resistant Enterobacteriaceae (CRE) and Vancomycin Resistant Enterococci (VRE) Biofilms by Antibiotic-Loaded Calcium Sulfate Beads

Carbapenem-resistant Enterobacteriaceae (CRE) and vancomycin-resistant Enterococci (VRE) have emerged as multidrug-resistant (MDR) pathogens associated with periprosthetic joint infections (PJI). In this study, we evaluated the efficacy of antibiotic-loaded calcium sulfate beads (ALCSB) in inhibiting bacterial growth, encouraging biofilm formation and killing preformed biofilms of CRE and VRE. Three strains of Klebsiella pneumoniae (KP) and a strain of Enterococcus faecalis (EF) were used. ALCSB of 4.8-mm diameter were loaded with vancomycin (V) and gentamicin (G), V and rifampicin (R), V and tobramycin (T) or R and meropenem (M), and placed onto tryptic soy agar (TSA), spread with one of the test strains and incubated for 24 h at 37 °C. Beads were transferred daily onto fresh TSA spread plates and the zone of inhibition (ZOI) was recorded until no inhibition was observed. ALCSB containing R + M or R + V produced the most extensive ZOI up to 5 weeks. Biofilm prevention efficacy was investigated by challenging ALCSB daily with 5 × 10⁵ CFU/mL bacterial cells and analyzing for biofilm formation at challenges 1, 2 and 3. In the biofilm killing experiments, ALCSB were added to pre-grown 3-day biofilms of KP and EF strains, which were then analyzed at days 1 and 3 post-exposure. The CFU counts and confocal images of the attached cells showed that ALCSB treatment reduced colonization and biofilm formation significantly (5–7 logs) with combinations of R + M or R + V, compared to unloaded beads. This study provides evidence that the local release of antibiotics from ALCSB may be useful in treating the biofilms of multidrug-resistant strains of CRE and VRE.

Single-stage treatment of chronic localized tibial osteomyelitis with local debridement and antibiotic-loaded calcium sulfate implantation: a retrospective study of 42 patients

Background

Although various methods have been introduced, the management of chronic tibial osteomyelitis remains a challenge. This study aims to assess a combined treatment method, local debridement combined with antibiotic-loaded calcium sulfate implantation, for the management of the local (Cierny-Mader type III) tibial osteomyelitis.

Methods

Forty-two patients (43 limbs) with type III tibial osteomyelitis, from January 2012 to December 2018, who received the treatment method mentioned above were included in the study. The infection remission rate, recurrence rate, complications rate, and bone healing rate were respectively analyzed.

Results

With a mean follow-up of 42.8 months, 38 limbs (37 patients) (88.4%, 38/43) achieved infection remission without recurrence. Among those patients pain, limitation of movement, sinus tracts, topical redness, and swelling were generally eliminated. Only 4 patients felt slight pain after a long-distance walk, while another 6 patients showed minor but acceptable discomfort in affected limbs. Five patients (11.6%) suffered from osteomyelitis recurrence that required secondary surgical and medical treatment, but no amputation was necessary to eliminate the infection. Prolonged aseptic drainage was the most frequent complication that was observed in 13 patients (30.0%). They were successfully managed by appropriate wound caring in 10 patients and by surgical intervention, months later, in 3 patients. According to the final X-ray examination, bone losses caused by local debridement were generally repaired, though the shape of the tibia was not well-restored to its initial form in 17 limbs. No fracture was recorded during follow-up.

Conclusion

Local debridement combined with antibiotic-loaded calcium sulfate implantation is effective and safe in a single-stage treatment of chronic Cierny-Mader III tibial osteomyelitis.

The Use of Calcium Sulphate beads in Periprosthetic Joint Infection, a systematic review

Purpose: To assess the use of calcium sulphate (CS) beads in the management of knee and hip periprosthetic joint infections (PJI) in terms of outcomes, complications and re-infection rates.

Methods: A search of NICE healthcare database advanced search (HDAS) was conducted from its year of inception to October 2019 with the keywords: “Calcium Sulphate Beads” or “Calcium Sulfate Beads” or “Antibiotics beads” or “Stimulan” and “Arthroplasty” or “Hip Replacement” or “Knee Replacement” and “Periprothetic joint infection” or “Debridement, Antibiotics and implant retention” or “Revision”. A quality assessment was performed using the NIH study Quality Assessment Tool for case series.

Results: Out of relevant 74 articles, 5 articles met the inclusion criteria. Variable outcomes and success rates have been reported in most of the patients. A small number of wound discharges and heterotrophic ossification (HO) were reported, which are occasionally symptomatic. Hypercalcemia is identified as a potential risk with the use of CS beads especially with doses over 40 cc per operation. The influence of CS beads on reinfection rate is reported in 4 out of 5 articles. Due to the case-mix and heterogenicity of the patients involved and the causative microorganism reported as well as varied procedures are undertaken including one and two stages revision and Debridement, Antibiotics and implant retention (DAIR), the influence of CS beads varied from high success to poor outcome. The poor outcome is higher if the primary procedure for the management of hip and knee PJI is DAIR rather than full revision.

Conclusions: The use of CS beads in the treatment of PJI is a useful technique in delivering high doses of antibiotics locally. A favourable outcome is reported when antibiotics loaded CS is used as an adjuvant to revision procedure for PJI in hip and knee arthroplasty compared to its use as an adjuvant to DAIR procedure. There has been an increase in complications when higher volumes of beads are used, especially in subcutaneous structures and in high-risk patients. Another possible theoretical and unreported complication of CS beads is accelerating the wear rate in the artificial joint due to the possibility of causing abrasion to the bearing surfaces. The current evidence is not enough to indicate the superiority of antibiotic-loaded CS beads as an adjuvant for the treatment of PJI in Hip and Knee arthroplasty.

Use of Stimulan absorbable calcium sulphate beads in revision lower limb arthroplasty: Safety profile and complication rates

Aims

Calcium sulphate has traditionally been used as a filler of dead space arising during surgery. Various complications have been described following the use of Stimulan bio-absorbable calcium sulphate beads. This study is a prospective observational study to assess the safety profile of these beads when used in revision arthroplasty, comparing the complication rates with those reported in the literature.

Methods

A total of 755 patients who underwent 456 revision total knee arthroplasties (TKA) and 299 revision total hip arthroplasties (THA), with a mean follow-up of 35 months (0 to 78) were included in the study.

Results

A total of 32 patients (4.2%) had wound drainage, and this was higher with higher bead volumes and in McPherson grade C patients. There was also a significantly higher bead volume in the 41 patients who developed hypercalcaemia, two of which were symptomatic (p < 0.0001). A total of 13 patients (1.7%) had heterotopic ossification (HO). There was no statistically significant relationship between the development of HO and bead volume (p > 0.05).

Conclusion

The strength of this study lies in the large number of patients and the detailed data collection, making it the most comprehensive report available in the literature on the use of calcium sulphate-based bone substitutes.Cite this article: R. Kallala, W. Edwin Harris, M. Ibrahim, M. Dipane, E. McPherson. Use of Stimulan absorbable calcium sulphate beads in revision lower limb arthroplasty: Safety profile and complication rates. Bone Joint Res 2018;7:570-579. DOI: 10.1302/2046-3758.710.BJR-2017-0319.R1.

Evaluation of Antibiotic-Releasing Triphasic Bone Void Filler In-Vitro

Bone void fillers (BVFs) containing calcium sulfate, tricalcium phosphate (TCP), and hydroxyapatite can be loaded with antibiotics for infection treatment or prevention under surgeon-directed use. The aim of this study was to characterize the handling and elution properties of a triphasic BVF loaded with common antibiotics. BVF was mixed with vancomycin and/or tobramycin to form pellets, and the set time was recorded. A partial refreshment elution study was conducted with time points at 4, 8, and 24 h, as well as 2, 7, 14, 28, and 42 days. Effects on dissolution were evaluated in a 14-day dissolution study. Set time increased to over 1 h for groups containing tobramycin, although vancomycin had a minimal effect. Pellets continued to elute antibiotics throughout the 42-day elution study, suggesting efficacy for the treatment or prevention of orthopedic infections. BVF containing vancomycin or tobramycin showed similar dissolution at 14 days compared to BVF without antibiotics; however, BVF containing both antibiotics showed significantly more dissolution.

In Vitro Effect of Vancomycin on the Viability of Articular Chondrocytes

OBJECTIVES

To characterize the in vitro toxicity of vancomycin on articular cartilage.

METHODS

Osteochondral samples extracted from fresh, juvenile porcine stifle (knee) joints were exposed to vancomycin saline concentrations of 2, 5, and 10 mg/mL and compared with a saline and nonsaline treated control. Comparison of chondrocyte viability was assessed with histology examination of chondrocyte degeneration using the Mankin criteria and a live/dead staining using ethidium homodimer-2 and calcien acetoxymethylester stain and confocal laser scanning microscopy.

RESULTS

A comparison of chondrocyte viability in the control sample and 2 mg/mL group showed no statistical difference (P = 0.38). The chondrocyte toxicity was statistically significantly higher in both the 5 mg/mL (P = 0.003) and 10 mg/mL (P < 0.001) experimental groups in comparison to the control sample. Chondrocyte death increased in a statistically significant dose-dependent fashion. Histologically, the Mankin scores were higher for the saline-treated group in comparison to the untreated control group.

CONCLUSIONS

Vancomycin is toxic to articular chondrocytes in concentrations of 5 mg/mL and greater. Strategies for controlling concentration must be developed before routine application of topical antibiotics around synovial joints is performed.

Biofilm prevention of gram-negative bacterial pathogens involved in periprosthetic infection by antibiotic-loaded calcium sulfate beads in vitro

Biofilm formation represents a key stage in the pathogenesis of prosthetic infections (PIs). More tolerant to antibiotics than their planktonic counterparts, biofilm bacteria are difficult to eradicate using conventional therapeutic regimes. A common approach in PI management is the adjunctive use of localised antibiotics in addition to systemic administration in an attempt to protect the implant from colonisation by infiltrating bacteria. This study evaluates the antibacterial and antibiofilm efficacy of antibiotic-loaded dissolvable calcium sulphate, previously shown to be effective against key gram-positive pathogens, against gram-negative species important in the establishment of chronic infection in PIs. Synthetic calcium sulfate beads loaded with tobramycin, vancomycin and both antibiotics in combination were assessed for their ability to eradicate planktonic Acinetobacter baumannii, Pseudomonas aeruginosa and Klebsiella pneumoniae strains. The efficacy of the beads in preventing biofilm formation and eliminating established biofilms over multiple days was evaluated using confocal laser scanning microscopy (CSLM) imaging combined with image analysis and viable cell counts. Beads loaded with antibiotics demonstrated effective eluting concentrations for up to 37 d depending on the bacterial strain. In the presence of repeated bacterial challenges, antibiotic-loaded beads prevented bacterial colonisation and significantly reduce biofilm formation for the duration of the assay (7 d). Complete eradication of established biofilms was more difficult with evidence of biofilm regrowth after 1 week of contact with antibiotic-loaded beads, despite data suggesting a complete kill was achieved at earlier timepoints of 24 h and 72 h in the case of K. pneumoniae and P. aeruginosa. This study provides further evidence that calcium sulfate beads loaded with vancomycin and tobramycin may be a useful adjunctive component to the successful management of PIs.