Dual-controlled-release dual-antibiotic-loaded bone scaffolds: Development and in vivo/in vitro study

Treatment of infected lower limb bone defects using the bone transport with locking plate technique (BTLP): A retrospective case series of 90 patients.

We fabricated a biodegradable antibiotic-eluting poly(d,l)-lactide-co-glycolide nanofiber-loaded deproteinized bone (ANDB) scaffold that provided sustained delivery of vancomycin to repair methicillin-resistant Staphylococcus aureus bone defects. To fabricate the biodegradable ANDB, poly(d,l)-lactide-co-glycolide and vancomycin were first dissolved in 1,1,1,3,3,3-hexafluoro-2-propano. The solution was then electrospun to produce biodegradable antibiotic-eluting membranes that were deposited on the surface of bovine deproteinized cancellous bone. We used scanning electron microscopy to determine the properties of the scaffold. Both elution and high-performance liquid chromatography assays were used to evaluate the invitro vancomycin release rate from the ANDB scaffold. Three types of scaffolds were co-cultured with bacteria to confirm the invitro antibacterial activity. The infected bone defect rabbit model was induced by injecting 10(7) colony forming units of a methicillin-resistant Staphylococcus aureus strain into the radial defect of rabbits. Animals were then separated into treatment groups and implanted according to the following scheme: ANDB scaffold in group A, poly(d,l)-lactide-co-glycolide nanofiber-loaded deproteinized bone (NDB) scaffold with intravenous (i.v.) vancomycin in group B, and NDB scaffold alone in group C. Treatment efficacy was evaluated after eight weeks using radiological, microbiological, and histological examinations. Invitro results revealed that biodegradable ANDB scaffolds released concentrations of vancomycin that were greater than the minimum inhibitory concentration for more than four weeks. Bacterial inhibition tests also confirmed antibacterial efficacy lasted for approximately four weeks. Radiological and histological scores obtained invivo revealed significant differences between groups A, B and C. Importantly, group A had significantly lower bacterial load and better bone regeneration when compared to either group B or C. Collectively, these results show that our fabricated ANDB scaffolds possess: (1) effective bactericidal activity against methicillin-resistant Staphylococcus aureus, (2) the ability to promote site-specific bone regeneration, and (3) the potential for use in the treatment of infected bone defects.

Background Treating infectious bone defects combined with large soft-tissue lesions poses significant clinical challenges. Herein, we introduced a modified two-stage treatment approach involving the implantation of 3D-printed prostheses and flap repair to treat large segmental infectious tibial bone defects. Method We conducted a retrospective study of 13 patients treated at our center between April 2018 and March 2022 for tibial infections owing to posttraumatic infection and chronic osteomyelitis combined with soft tissue defects. The average defect length was 14.0 cm (range, 5.7–22.9 cm). The flap area ranged from 14 × 5 to 15 × 8 + 25 × 15 cm. Sural neurocutaneous, lesser saphenous neurocutaneous, and local fasciocutaneous flaps were used to repair the skin defects. In the second stage, 3D-printed prostheses were designed and implanted. Union rate, complications, and functional outcomes were assessed at the final follow-up. Result The average follow-up period was 31.1 months (range, 17–47 months), with an average interval of 208.1 days (range, 139–359 days) between the two stages. According to our criteria, 7 of the 13 patients achieved radiographic healing without intervention. Two patients developed prosthesis-related complications and underwent revision surgery. Two patients experienced recurrent infections leading to prosthesis removal and debridement surgery, with the infection ultimately eradicated in one and the other undergoing amputation. Three patients experienced noninfectious flap-related complications, however, all eventually healed through surgical intervention. Conclusion The use of 3D-printed porous titanium prostheses combined with flap soft-tissue repair for the treatment of infectious tibial bone defects did not increase the rate of infection recurrence and provided good functional recovery, offering more options for the treatment of infectious bone defects.

There is no consensus for the management of critical infected bone defects. The purpose of this study was to produce a vancomycin-impregnated electrospun polycaprolactone (PCL) membrane for the treatment of infected critical bone defects, and test it in a rabbit model. Electrospinning produced a resorbable PCL fiber membrane containing vancomycin approximately 1 mm in thickness, with a pore diameter of <10 μm. Femur defects were made in the limbs of 18 rabbits and infected with Staphylococcus aureus. The rabbits were divided into three groups according to treatment: (1) Experimental group: rabbit freeze-dried allogeneic bone graft and the vancomycin-PCL membrane. (2) Control group 1: bone graft. (3) Control group 2: vancomycin-PCL membrane only. Culture showed no difference in osteoclast activity between the three groups. Transwell testing showed that almost no fibroblasts passed through the membrane during the first 24 h, but some fibroblasts were able to pass it after 72 h. At 12 weeks after surgery, there was significantly less inflammatory cell infiltration in the experimental compared to the control groups. New bone formation and fracture bone callus were greater in the experimental group than control groups. We thus conclude the resorbable electrospun vancomycin-impregnated PCL membrane was effective at controlling bone infection, and in the regeneration of bone in a critical bone defect animal model.

The clinical treatment of infectious bone defects is difficult and time-consuming due to the coexistence of infection and bone defects, and the simultaneous control of infection and repair of bone defects is considered a promising therapy. In this study, a dual-drug delivery scaffold system was fabricated by the combination of a three-dimensional (3D) printed scaffold with hydrogel for infected bone defects repair. The 3D printed polycaprolactone scaffold was incorporated with biodegradable mesoporous silica nanoparticles containing the small molecular drug fingolimod (FTY720) to provide structural support and promote angiogenesis and osteogenesis. The vancomycin (Van)-loaded hydrogel was prepared from aldehyde hyaluronic acid (AHA) and carboxymethyl chitosan (NOCC) by the Schiff base reaction, which can fill the pores of the 3D-printed scaffold to produce a bifunctional composite scaffold. The in vitro results demonstrated that the composite scaffold had Van concentration-dependent antimicrobial properties. Furthermore, the FTY720-loaded composite scaffold demonstrated excellent biocompatibility, vascularization, and osteogenic ability in vitro. In the rat femoral defect model with bacterial infection, the dual-drug composite scaffold showed a better outcome in both infection control and bone regeneration compared to other groups. Therefore, the prepared bifunctional composite scaffold has potential application in the treatment of infected bone defects.

BackgroundThe induced membrane technique has achieved good clinical results in the treatment of infected bone defects, and external fixation is the main method, but it causes inconvenience and complications in patients. In this study, our objective was to investigate the outcomes of using an antibiotic cement-coated locking plate as a temporary internal fixation in the first stage of the surgical induced membrane technique for treating extremities with infected bone defects.MethodsWe retrospectively analysed patients with lower extremity infected bone defects in our department between January 2013 and December 2017. All patients were treated with the induced membrane technique. In the first stage, the defects were stabilized with an antibiotic cement-coated locking plate as a temporary fixation after debridement, and polymethyl methacrylate cement was implanted to induce the formation of a membrane. In the second stage, bone grafting rebuilt the bone defects after infection control, and the temporary fixation was changed to a stronger fixation.ResultsA total of 183 patients were enrolled, with an average follow-up duration of 32.0 (12–66) months. There were 154 males and 29 females with an average age of 42.8 (10–68) years. The infection sites included 81 femurs, 100 tibias and 2 fibulas. After the first stage of treatment (infection control), 16 (8.7%) patients had recurrence of infection. In terms of the incidence of complications, 4 patients had poor wound healing, 2 patients had fixation failure and 1 patient had femoral fracture due to a fall. After the second stage of treatment (bone reconstruction), there were 24 (13.1%) recurrences of infection, with a mean time of 9.9 months (range 0.5 to 36). Among them, 18 patients underwent bone grafting after re-debridement, 6 received permanent placement of antibiotic bone cement after debridement and 2 patients refused further treatment and chose amputation. Bone healing was achieved in 175 (95.9%) patients at the last follow-up, and the average time to bone union was 5.4 (4–12) months.ConclusionsAntibiotic cement-coated locking plates have good clinical effects in the control of bone infection, but attention must be paid to the possible difficulty of skin coverage when applied in calves.

Outcomes of Masquelet technique combined with gentamicin-cement-coated rigid nails in the treatment of infected bone defects: A retrospective review.

Background Infectious bone defects are characterized by persistent bacterial invasion and an immune microenvironment imbalance, which significantly hinders bone regeneration. Recently, numerous bone repair materials have been developed to address the complex pathological microenvironment associated with infectious bone defects. However, dynamic changes in the defect size after infectious debridement pose a significant challenge for achieving effective bone integration of artificial bone grafts. Methods Using low-temperature printing combined with the freeze-drying technology, a shape-memory scaffold with a biomimetic porous structure of cancellous bones was fabricated by compositing left-handed poly(L-lactic acid)-trimethylene carbonate (PLLA-TMC) with citric acid-modified hydroxyapatite (CHA). The scaffold (PT/CHA) was further coated with a metal-polyphenol network tannic acid-magnesium (TA-Mg) on its surface through the "mussel" effect, enabling the sequential treatment of infectious bone defects. Results The scaffold can adaptively integrate with defect interfaces at the physiological temperature (37°C), achieving superior bone integration performance. The incorporation of citric-acid-modified hydroxyapatite effectively optimizes the polymer-inorganic phase printing ink system, significantly enhancing the mechanical strength and mineralization capacity of the scaffold. Meanwhile, the external tannic-acid-magnesium metal-polyphenol coating (TA-Mg) demonstrates excellent pathogen clearance properties both in vitro and in vivo. It also influences macrophage polarization to regulate the immune microenvironment, ultimately promoting bone regeneration in infectious bone defects. Conclusions The PT/CHA@TA-Mg scaffold achieves bone integration through adaptive filling and enables the multi-stage treatment of infectious bone defects via antibacterial, immune-regulatory and osteogenic differentiation.

Objective To investigate the efficacy of quick antiinfective spacer combined with Masquelet technique in the treatment of infectious bone defects. Methods From January 2006 to June 2013, we treated 52 patients with infectious bone defects. They were 46 men and 6 women, aged from 19 to 46 years (average, 31.3 years). They were treated by debridement and anti-infection therapy at the first stage when the individualized quick antiinfective spacers were prepared (a mixture of antibiotics and bone cement powder added by polymethyl methacrylate morphon). At the second stage, the bone defects were repaired using Masquelet technique before they were internally fixated. Results The 52 patients were followed up for an average time of 21 months (range, from 13 to 28 months). All the infectious bone defects were healed. X-ray examination showed that the bone mineral density at the bone grafting area increased significantly compared with pre-operation, suggesting granular bone resorption and new bone formation. All the fractures obtained bony union after 6 to 10 months (average, 7.5 months), without recurrence of infection or teratogenesis. Conclusions Quick antiinfective spacer can control local infection in the early period of bone defect by sustainable local release of effective antibiotics of high concentrations while it maintains limb length, increases the stability of fracture ends, and reduces contracture of bone and soft tissue. All these roles may create favorable conditions for late repair, reduce the infection rate and improve the efficacy of early management. Key words: Fractures, bone; Infection; Masquelet technique; Wound and injuries; Fracture fixation, internal

Background Longbone infected bone defect remains a great challenge due to multiple surgeries, long-term treatment duration, and uncertain prognosis. Treatment principles include eradication/debridement, stabilization, and antibiotic administration. An antibiotic cement-coated nail has shown great prospects due to both local antibiotic elution and stabilization of bone defects. However, the current fabrication technique remains to be improved. Methods For the first time, we described a new method for custom-made cement-coated nail fabrication based on a 3D printing technique. A retrospective study of 19 consecutive patients with long bone infected bone defects from one medical center was conducted who met the inclusion and exclusion criteria from November 2016 to May 2020. The treatment involved thorough debridement, custom-made antibiotic cement-coated nail filling, and culture-specific systemic antibiotic treatment guided by a multidisciplinary team. Clinical and radiographic examinations (X-ray and CT scans) were used to evaluate bony union. Clinical and laboratory examinations were used to evaluate the infection control. The SF-36 score was used to evaluate patients' quality of life pre- and postoperatively. Results The mean follow-up was 98.8 weeks (ranging from 40 to 192). All cases achieved infection control, 3 cases achieved bone healing after one-stage operation, and 12 cases achieved bone healing after a two-stage bone graft procedure. At the last follow-up, none of the 19 patients had infection recurrence or 1 case had failure of the protective plate. The pre- and postoperative SF-36 score showed that there were statistical differences in all the 9 aspects. Conclusions The precise custom-made antibiotic cement-coated intramedullary nail through the 3D printing technique used in this study is an effective strategy for the treatment of infected bone defects of long bone. This technique may help to increase the infection control rate and promote bone healing.

Objective To investigate the effects of xenogenic bone with chitosan/norvancomycin sustained-release biomaterials in treating infectious bone defects in rabbits. Methods Xenogenic bone with chitosan/norvancomycin sustained-release biomaterials was made by electrospinning technique. Rabbit infectious bone defect models were made by Methicillin-resistant Staphylococcus aureus. A successful model was evaluated with the standard of more than three points in Norden score assessment. All models were divided into two groups by random number table method, with eight models in each. The control group was treated with surgical debridement, and the experimental group was implanted with bone particles of xenogenic bone with chitosan/norvancomycin sustained-release system after debridement. Postoperatively, general conditions, X-ray, histological results of HE staining, and bacteriological examination results of the rabbits were observed. Results X-ray showed significant bone defects, sequestration, periosteal reaction, and soft tissue swelling after one month of modeling, with Norden score of (3.84±0.52)points. The general conditions were good and the sinus tracts were healed in experimental group after two months of treatment. The control group demonstrated generally poor conditions with swollen sinus and purulent discharge. Two rabbits were died of sepsis. The pathological scores of tibial were (0.41±0.08)points in experimental group, and (3.27±0.26)points in control group by gross observation. The pathological score of experimental group was significantly lower than control group(P<0.05). The bone defects were basically repaired in experimental group. The longest diameter of bone defect in experimental group was (0.11±0.02)cm, significantly smaller than (0.48±0.06)cm in control group (P<0.05). There were no obvious signs of osteomyelitis and the bone defects were well repaired in experimental group. Periosteal reaction, soft tissue swelling, a substantial number of bone destruction, and sequestration were observed in control group. The Norden score was (1.32±0.23)points in experimental group, lower than (5.21±0.48)points in control group(P<0.05). HE staining showed a large amount of trabecular bone formation, bone cell formation, and fibrous hyperplasia in experimental group, with no obvious signs of infection. On the other hand, infiltration of inflammatory cells, necrotic tissue, and sequestration were observed in control group. The histological score was(0.61±0.10) points in experimental group, lower than (4.21±0.41) points in control group (P<0.05). The negative rate of bacterial culture in experimental group was 33%, lower than 100% in control group (P<0.05). Conclusion Xenogenic bone with chitosan/norvancomycin sustained-release biomaterials has excellent effect in infection clearance and bone defect reparation in treatment of infectious bone defects in rabbits. Key words: Osteomyelitis; Chitosan; Anti-bacterial agents; Drug delivery systems

Vancomycin-encapsulated hydrogel loaded microarc-oxidized 3D-printed porous Ti6Al4V implant for infected bone defects: Reconstruction, anti-infection, and osseointegration

BackgroundThe choice of bone substitutes for the treatment of infected bone defects (IBDs) has attracted the attention of surgeons for years. However, single-stage bioabsorbable materials that are used as carriers for antibiotic release, as well as scaffolds for BMSC sheets, need further exploration. Our study was designed to investigate the effect of vancomycin-loaded calcium sulfate hemihydrate/nanohydroxyapatite/carboxymethyl chitosan (CSH/n-HA/CMCS) hydrogels combined with BMSC sheets as bone substitutes for the treatment of IBDs.MethodsBMSCs were harvested and cultured into cell sheets. After the successful establishment of an animal model with chronic osteomyelitis, 48 New Zealand white rabbits were randomly divided into 4 groups. Animals in Group A were treated with thorough debridement as a control. Group B was treated with BMSC sheets. CSH/n-HA/CMCS hydrogels were implanted in the treatment of Group C, and Group D was treated with CSH/n-HA/CMCS+BMSC sheets. Gross observation and micro-CT 3D reconstruction were performed to assess the osteogenic and infection elimination abilities of the treatment materials. Histological staining (haematoxylin and eosin and Van Gieson) was used to observe inflammatory cell infiltration and the formation of collagen fibres at 4, 8, and 12 weeks after implantation.ResultsThe bone defects of the control group were not repaired at 12 weeks, as chronic osteomyelitis was still observed. HE staining showed a large amount of inflammatory cell infiltration around the tissue, and VG staining showed no new collagen fibres formation. In the BMSC sheet group, although new bone formation was observed by gross observation and micro-CT scanning, infection was not effectively controlled due to unfilled cavities. Some neutrophils and only a small amount of collagen fibres could be observed. Both the hydrogel and hydrogel/BMSCs groups achieved satisfactory repair effects and infection control. Micro-CT 3D reconstruction at 4 weeks showed that the hydrogel/BMSC sheet group had higher reconstruction efficiency and better bone modelling with normal morphology. HE staining showed little aggregation of inflammatory cells, and VG staining showed a large number of new collagen fibres.ConclusionsOur preliminary results suggested that compared to a single material, the novel antibiotic-impregnated hydrogels acted as superior scaffolds for BMSC sheets and excellent antibiotic vectors against infection, which provided a basis for applying tissue engineering technology to the treatment of chronic osteomyelitis.

In this study, we treated infected ankle bone defects with the induced membrane two-stage technique. The ankle was fused with a retrograde intramedullary nail in the second stage, and the aim of this study was to observe the clinical effect. We retrospectively enrolled patients with infected bone defects of the ankle admitted to our hospital between July 2016 and July 2018. In the first stage, the ankle was temporarily stabilized with a locking plate, and antibiotic bone cement was used to fill the defects after debridement. In the second stage, the plate and cement were removed, the ankle was stabilized with a retrograde nail, and tibiotalar-calcaneal fusion was performed. Then, autologous bone was used to rebuild the defects. The infection control rate, fusion success rate and complications were observed. Fifteen patients were enrolled in the study with an average follow-up of 30 months. Among them, there were 11 males and 4 females. The average bone defect length after debridement was 5.3 cm (2.1–8.7 cm). Finally, 13 patients (86.6%) achieved bone union without recurrence of infection, and 2 patients experienced recurrence after bone grafting. The average ankle-hindfoot function score (AOFAS) increased from 29.75 ± 4.37 to 81.06 ± 4.72 at the last follow-up. The induced membrane technique combined with a retrograde intramedullary nail for the treatment of infected bone defects of the ankle after thorough debridement is an effective treatment method.

Dual-functional composite scaffolds for inhibiting infection and promoting bone regeneration