Effects of bead size and polymerization in PMMA bone cement on vancomycin release

Application of the induced membrane technique of tibia using extracorporeal vs. intracorporeal formation of a cement spacer: a retrospective study

Background

There were two ways of preparing the cement spacer: intracorporeal and extracorporeal formation. This study aimed to investigate the outcomes of extracorporeal vs. intracorporeal formation of a spacer using the induced membrane technique (IMT) for repairing bone defects of the tibia.

Methods

Sixty-eight patients with tibial defects treated with IMT were analyzed retrospectively. According to the mode of bone cement preparation, patients were divided into intracorporeal and extracorporeal groups (36 vs. 32 respectively). All patients were followed up for 12–48 months (average 18.7 months). The time interval between the first and second stages, the time required to remove the spacer, injury of the IM or bone ends, bone healing and infection control, as well as the functional recovery (Johner—Wruhs scoring), were compared.

Results

There was no significant difference in the preoperative data between the two groups (P > 0.05). There was no significant difference in the time interval (12.64 ± 4.41vs. 13.22 ± 4.96 weeks), infection control (26/28 vs. 20/23), bone healing time (7.47 ± 2.13vs. 7.50 ± 2.14 mos), delayed union (2/36 vs. 2/32), nonunion (2/36 vs. 1/32), an excellent or good rate of limb functional recovery (30/36 vs. 26/32) between the intracorporeal and extracorporeal groups (P > 0.05). However, the time required to remove (3.97 ± 2.34 min) was longer and the injury of IM or bone ends (28/36) was greater in the intracorporeal group than those in the extracorporeal group (0.56 ± 0.38 min and 1/32, respectively), showing a significant difference (P < 0.05).

Conclusion

Both approaches were shown to have similar effects on bone defect repair and infection control. However, intracorporeal formation had advantages in terms of additional stability, while extracorporeal formation had advantages in terms of removal. Therefore, the specific method should be selected according to specific clinical needs. We recommended the extracorporeal or the modified extracorporeal formation in most cases.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05355-0.

Release characteristics of enoxaparin sodium-loaded polymethylmethacrylate bone cement

BACKGROUND

This study aimed to prepare the polymethylmethacrylate (PMMA) bone cement release system with different concentrations of enoxaparin sodium (ES) and to investigate the release characteristics of ES after loading into the PMMA bone cement.

METHODS

In the experimental group, 40 g Palacos®R PMMA bone cement was loaded with various amount of ES 4000, 8000, 12,000, 16,000, 20,000, and 24,000 AXaIU, respectively. The control group was not loaded with ES. Scanning electron microscopy (SEM) was used to observe the surface microstructure of the bone cement in the two groups. In the experiment group, the mold was extracted continuously with pH7.4 Tris-HCL buffer for 10 days. The extract solution was collected every day and the anti-FXa potency was measured. The experiment design and statistical analysis were conducted using a quantitative response parallel line method.

RESULTS

Under the SEM, it was observed that ES was filled in the pores of PMMA bone cement polymer structure and released from the pores after extraction. There was a burst effect of the release. The release amount of ES on the first day was 0.415, 0.858, 1.110, 1.564, 1.952, and 2.513, respectively, from the six groups with various ES loading amount of 4000, 8000, 12,000, 16,000, 20,000, and 24,000 AXaIU, all reaching the peak of release on the first day. The release decreased rapidly on the next day and entered the plateau phase on the fourth day.

CONCLUSION

The prepared ES-PMMA bone cement has high application potential in orthopedic surgery. ES-PMMA bone cement shows good drug release characteristics. The released enoxaparin sodium has a local anti-coagulant effect within 24 h after application, but it will not be released for a long time, which is complementary to postoperative anti-coagulation therapy.

Antimicrobial Activity of 3D-Printed Poly(ε-Caprolactone) (PCL) Composite Scaffolds Presenting Vancomycin-Loaded Polylactic Acid-Glycolic Acid (PLGA) Microspheres

BACKGROUND The aim of this study was to design and test a novel composite scaffold with antibacterial efficacy for treating bone infections using a three-dimensional (3D) printed poly(ε-caprolactone) (PCL) scaffold coated with polydopamine (PDA) for the adsorption of polylactic acid-glycolic acid (PLGA) microspheres loaded with vancomycin. MATERIAL AND METHODS Vancomycin-loaded PLGA microspheres were produced by the double-emulsion method, and microsphere morphology, drug-loading dosage, encapsulation efficiency, average diameter, and release characteristics were examined. Composite scaffolds were prepared by adsorption of the microspheres on PDA-coated, 3D-printed PCL scaffolds, and scaffold morphology, biocompatibility, vancomycin release, and antibacterial efficacy were evaluated. RESULTS The vancomycin-loaded microspheres were smooth, round, uniform in size, and had no adhesion phenomenon, and exhibited sustained release of vancomycin from the microspheres for more than 4 weeks. Upon modification with PDA, the PCL scaffold changed from white to black, and after microsphere adsorption, dot-like white particles were seen. On scanning electron microscopy, PDA particles were observed on the PCL/PDA composite scaffolds, and PLGA microspheres were evenly dispersed over the PDA coating on the PCL/PDA/PLGA composite scaffolds. Cell viability assays showed that the adhesion and proliferation of rabbit bone mesenchymal stem cells were greater on the PCL/PDA scaffolds than on unmodified PCL scaffolds. Microsphere adsorption had no significant effect on cell proliferation. In vitro release of vancomycin from the composite scaffolds was observed for more than 4 weeks, and observation of the inhibition zone on agar plates of Staphylococcus aureus showed that the scaffolds maintained their antibacterial effect for more than 4 weeks. CONCLUSIONS The 3D-printed, PDA-coated PCL scaffold carrying vancomycin-loaded PLGA microspheres exhibited good biocompatibility and a sustained antibacterial effect in vitro.

[Effectiveness analysis of induced membrane technique in the treatment of infectious bone defect]

Objective

To evaluate the effectiveness of induced membrane technique in the treatment of infectious bone defect.

Methods

Thirty-six patients (37 bone lesions) with infectious bone defects were treated with induced membrane technique between January 2011 and June 2014. There were 28 males and 8 females with an average age of 36 years (range, 20-68 years). All bone defects were post-traumatic infectious bone defect. The bone defect was located at the tibia and fibula in 24 cases (25 bone lesions), at femurs in 6 cases (6 bone lesions), at ulnas and radii in 2 cases (2 bone lesions), at calcanei in 3 cases (3 bone lesions), and at clavicle in 1 case (1 bone lesion). The average time between onset and the treatment of induced membrane technique was 6.2 months (range, 0.5-36.0 months); 15 patients were acute infections (disease duration was less than 3 months). At the first stage, after the removal of internal fixator (applicable for the patients who had internal fixation), complete debridement of infection necrotic bone tissue and surrounding soft tissue was performed and the bone defects were filled with antibiotic-impregnated cement spacers. If the bone was unstable after debridement, external fixator or plaster could be used for stabilization. Patients received sensitive antibiotics postoperatively. At the second stage (usually 6-8 weeks later), the cement spacer were removed, with preservation of the induced membrane formed by the spacer, and filled the bone defect with autologous iliac bone graft within the membrane.

Results

The hospitalization time after debridement was 17-30 days (mean, 22.2 days), and the hospitalization time after the second stage was 7-14 days (mean, 10 days). All the flaps healed uneventfully in 16 cases treated with local flap transposition or free flap grafting after debridement. One patient of femur fracture received Ilizarov treatment after recurrence of infection at 11 months after operation; 1 patient of distal femoral fracture received amputation after recurrence of infection at 1 month after operation; 1 patient of distal end of tibia and fibula fractures received ankle arthrodesis after repeated debridements due to the recurrence of infection; 1 patient of tibia and fibula fractures lost to follow-up. The other 32 patients (33 bone lesions) were followed up 1-5 years (mean, 2 years) without infection recurrence, and the infection control rate was 91.7% (33/36). All the patients had bony union, and the healing time was 4-12 months (mean, 7.5 months); no refracture occurred. One patient of femur bone defect had a lateral angulation of 15° and leg discrepancy of 1.5 cm. Superficial pin infection was observed in 7 cases and healed after intensive wound care and oral antibiotics. Adjacent joint function restriction were observed in 6 cases at last follow-up.

Conclusion

Induced membrane technique is a simple and reliable technique for the treatment of infectious bone defect. The technique is not limited to the size of the bone defect and the effectiveness is satisfactory.

Outcomes of cement beads and cement spacers in the treatment of bone defects associated with post-traumatic osteomyelitis

Background

Cement spacers (Masquelet technique) have traditionally been used for the treatment of segmental bone defects. However, no reports have used cement spacers for the treatment of small/partial segmental bone defects associated with osteomyelitis and compared the outcomes with cement beads.

Methods

We retrospectively analysed 40 patients with post-traumatic osteomyelitis of the tibia who underwent treatment, which was performed in two stages. In the first stage, thorough debridement was performed, and bone defects were filled with either antibiotic-impregnated cement beads (bead group, 18 patients) or spacers (spacer group, 22 patients). In the second stage, the cement beads or spacers were removed (for the spacer group, the induced membrane formed by the spacer was preserved) and the bone defects were filled with cancellous autografts.

Results

All patients in the bead group had small/partial segmental bone defects after debridement, while 3 patients in the spacer group had large/segmental bone defects.

The mean volume of bone defects of the spacer group (40.4 cm³) was significantly larger than that of the bead group (32.4 cm³). The infection control rate (88.9%,16/18 vs 90.9%, 20/22), bone healing time (8.5 months vs 7.5 months) and complication rates (22.2%, 4/18 vs 27.2%, 6/22) were comparable between bead group and spacer group.

Conclusion

The results of this study suggest that cement spacers may have an infection control rate comparable to cement beads in the treatment of bone defects associated with post-traumatic osteomyelitis. Furthermore, cement spacers could be used for the reconstruction of small/partial segmental bone defects as well as for large/segmental bone defects, whereas cement beads were not suitable for the reconstruction of large/segmental bone defects.

A Review of PMMA Bone Cement and Intra-Cardiac Embolism

Percutaneous vertebroplasty procedure is of major importance, given the significantly increasing aging population and the higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving the injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main effects of PMMA bone cement on the heart, and the extent of influence of the materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case reports.

Novel Bone-Targeting Agent for Enhanced Delivery of Vancomycin to Bone

We examined the pharmacokinetic properties of vancomycin conjugated to a bone-targeting agent (BT) with high affinity for hydroxyapatite after systemic intravenous administration. The results confirm enhanced persistence of BT-vancomycin in plasma and enhanced accumulation in bone relative to vancomycin. This suggests that BT-vancomycin may be a potential carrier for the systemic targeted delivery of vancomycin in the treatment of bone infections, potentially reducing the reliance on surgical debridement to achieve the desired therapeutic outcome.

Nanostructured platforms for the sustained and local delivery of antibiotics in the treatment of osteomyelitis

This article provides a critical view of the current state of the development of nanoparticulate and other solid-state carriers for the local delivery of antibiotics in the treatment of osteomyelitis. Mentioned are the downsides of traditional means for treating bone infection, which involve systemic administration of antibiotics and surgical debridement, along with the rather imperfect local delivery options currently available in the clinic. Envisaged are more sophisticated carriers for the local and sustained delivery of antimicrobials, including bioresorbable polymeric, collagenous, liquid crystalline, and bioglass- and nanotube-based carriers, as well as those composed of calcium phosphate, the mineral component of bone and teeth. A special emphasis is placed on composite multifunctional antibiotic carriers of a nanoparticulate nature and on their ability to induce osteogenesis of hard tissues demineralized due to disease. An ideal carrier of this type would prevent the long-term, repetitive, and systemic administration of antibiotics and either minimize or completely eliminate the need for surgical debridement of necrotic tissue. Potential problems faced by even hypothetically "perfect" antibiotic delivery vehicles are mentioned too, including (i) intracellular bacterial colonies involved in recurrent, chronic osteomyelitis; (ii) the need for mechanical and release properties to be adjusted to the area of surgical placement; (iii) different environments in which in vitro and in vivo testings are carried out; (iv) unpredictable synergies between drug delivery system components; and (v) experimental sensitivity issues entailing the increasing subtlety of the design of nanoplatforms for the controlled delivery of therapeutics.

Liquid dextran does not increase the elution rate of different antibiotics from bone cement

PURPOSE

To investigate the possibility of increasing elution of fosfomycin, gentamicin, clindamycin, and vancomycin by the addition of dextran fluid during the cement-mixing phase.

METHODS

In 12 test series, we produced standardized, antibiotic-loaded test specimens of cement, with and without addition of dextran, and determined their effectiveness against three reference pathogens in agar diffusion and elution tests.

RESULTS

In the test series using combined agents, Refobacin(®)-Palacos(®)R plus fosfomycin continuously produced the largest zone of inhibition, both against methicillin-sensitive Staphylococcus aureus (p = 0.009) and against methicillin-resistant Staphylococcus aureus (p = 0.009). The addition of dextran to the various test series had no useful effect on the size of the zone of inhibition for any of the antibiotics tested.

CONCLUSIONS

Dextran supplementation in Refobacin(®)-Palacos(®)R bone cement did not have the hope for positive effect on the elution rate of bound antibiotics.

Charcot foot and ankle with osteomyelitis

This paper presents a review of the current literature discussing topics of Charcot osteoarthropathy, osteomyelitis, diagnosing osteomyelitis, antibiotic management of osteomyelitis, and treatment strategies for management of Charcot osteoarthropathy with concurrent osteomyelitis.