Calcium sulfate induced versus PMMA-induced membrane in a critical-sized femoral defect in a rat model

Targeting micromotion for mimicking natural bone healing by using NIPAM/Nb2C hydrogel

Natural fracture healing is most efficient when the fine-tuned mechanical force and proper micromotion are applied. To mimick this micromotion at the fracture gap, a near-infrared-II (NIR-II)-activated hydrogel was fabricated by integrating two-dimensional (2D) monolayer Nb2C nanosheets into a thermally responsive poly(N-isopropylacrylamide) (NIPAM) hydrogel system. NIR-II-triggered deformation of the NIPAM/Nb2C hydrogel was designed to generate precise micromotion for co-culturing cells. It was validated that micromotion at 1/300 Hz, triggering a 2.37-fold change in the cell length/diameter ratio, is the most favorable condition for the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). Moreover, mRNA sequencing and verification revealed that micromotion-induced augmentation was mediated by Piezo1 activation. Suppression of Piezo1 interrupts the mechano-sensitivity and abrogates osteogenic differentiation. Calvarial and femoral shaft defect models were established to explore the biocompatibility and osteoinductivity of the Micromotion Biomaterial. A series of research methods, including radiography, micro-CT scanning, and immunohistochemical staining have been performed to evaluate biosafety and osteogenic efficacy. The in vivo results revealed that tunable micromotion strengthens the natural fracture healing process through the sequential activation of endochondral ossification, promotion of neovascularization, initiation of mineral deposition, and combinatory acceleration of full-thickness osseous regeneration. This study demonstrated that Micromotion Biomaterials with controllable mechanophysical characteristics could promote the osteogenic differentiation of BMSCs and facilitate full osseous regeneration. The design of NIPAM/Nb2C hydrogel with highly efficient photothermal conversion, specific features of precisely controlled micromotion, and bionic-mimicking bone-repair capabilities could spark a new era in the field of regenerative medicine.

Analysis of risk factors for the recurrence of osteomyelitis of the limb after treatment with antibiotic-loaded calcium sulfate and autologous bone graft

Objective

We aimed to evaluate the efficacy of antibiotic-loaded calcium sulfate combined with autologous iliac bone transplantation in the treatment of limb-localized osteomyelitis (Cierny-Mader type III) and analyze the causes and risk factors associated with infection recurrence.

Methods

Clinical data of 163 patients with localized osteomyelitis of the extremities treated with antibiotic-loaded calcium sulfate combined with autologous iliac bone transplantation in Xi'an Honghui Hospital from January 2017 to December 2022 were retrospectively analyzed. All patients were diagnosed with localized osteomyelitis through clinical examination and treated with antibiotic-loaded calcium sulfate combined with autologous iliac bone. Based on the infection recurrence status, the patients were divided into the recurrence group and the non-recurrence group. The clinical data of the two groups were compared using univariate analysis. Subsequently, the distinct datasets were included in the binary logistic regression analysis to determine the risk and protective factors.

Results

This study included 163 eligible patients, with an average age of 51.0 years (standard deviation: 14.9). After 12 months of follow-up, 25 patients (15.3%) experienced infection recurrence and were included in the recurrence group; the remaining 138 patients were included in the non-recurrence group. Among the 25 patients with recurrent infection, 20 required reoperation, four received antibiotic treatment alone, and one refused further treatment. Univariate analysis showed that education level, smoking, hypoproteinemia, open injury-related infection, and combined flap surgery were associated with infection recurrence (p < 0.05). Logistic regression analysis showed that open injury-related infection (odds ratio [OR] = 35.698; 95% confidence interval [CI]: 5.997-212.495; p < 0.001) and combined flap surgery (OR = 41.408; 95% CI: 5.806-295.343; p < 0.001) were independent risk factors for infection recurrence. Meanwhile, high education level (OR = 0.009; 95% CI: 0.001-0.061; p < 0.001) was a protective factor for infection recurrence.

Conclusion

Antibiotic-loaded calcium sulfate combined with autologous iliac bone transplantation is an effective method for treating limb-localized osteomyelitis. Patients without previous combined flap surgery and non-open injury-related infections have a relatively low probability of recurrence of infection after treatment with this surgical method. Additionally, patients with a history of smoking and hypoproteinemia should pay attention to preventing the recurrence of infection after operation. Providing additional guidance and support, particularly in patients with lower education levels and compliance, could contribute to the reduction of infection recurrence.

Mechanisms of the Masquelet technique to promote bone defect repair and its influencing factors

The Masquelet technique, also known as the induced membrane technique, is a surgical technique for repairing large bone defects based on the use of a membrane generated by a foreign body reaction for bone grafting. This technique is not only simple to perform, with few complications and quick recovery, but also has excellent clinical results. To better understand the mechanisms by which this technique promotes bone defect repair and the factors that require special attention in practice, we examined and summarized the relevant research advances in this technique by searching, reading, and analysing the literature. Literature show that the Masquelet technique may promote the repair of bone defects through the physical septum and molecular barrier, vascular network, enrichment of mesenchymal stem cells, and high expression of bone-related growth factors, and the repair process is affected by the properties of spacers, the timing of bone graft, mechanical environment, intramembrane filling materials, artificial membrane, and pharmaceutical/biological agents/physical stimulation.

Biodegradable poly(caprolactone fumarate) 3D printed scaffolds for segmental bone defects within the Masquelet technique

Segmental bone defects, often clinically treated with nondegradable poly(methylmethacrylate) (PMMA) in multistage surgeries, present a significant clinical challenge. Our study investigated the efficacy of 3D printed biodegradable polycaprolactone fumarate (PCLF)/PCL spacers in a one-stage surgical intervention for these defects, focusing on early bone regeneration influenced by spacer porosities. We compared nonporous PCLF/PCL and PMMA spacers, conventionally molded into cylinders, with porous PCLF/PCL spacers, 3D printed to structurally mimic segmental defects in rat femurs for a 4-week implantation study. Histological analysis, including tissue staining and immunohistochemistry with bone-specific antibodies, was conducted for histomorphometry evaluation. The PCLF/PCL spacers demonstrated compressive properties within 6 ± 0.5 MPa (strength) and 140 ± 15 MPa (modulus). Both porous PCLF/PCL and Nonporous PMMA formed collagen-rich membranes (PCLF/PCL: 92% ± 1.3%, PMMA: 86% ± 1.5%) similar to those induced in the Masquelet technique, indicating PCLF/PCL's potential for one-stage healing. Immunohistochemistry confirmed biomarkers for tissue regeneration, underscoring PCLF/PCL's regenerative capabilities. This research highlights PCLF/PCL scaffolds' ability to induce membrane formation in critical-sized segmental bone defects, supporting their use in one-stage surgery. Both solid and porous PCLF/PCL spacers showed adequate compressive properties, with the porous variants exhibiting BMP-2 expression and woven bone formation, akin to clinical standard PMMA. Notably, the early ossification of the membrane into the pores of porous scaffolds suggests potential for bone interlocking and regeneration, potentially eliminating the need for a second surgery required for PMMA spacers. The biocompatibility and biodegradability of PCLF/PCL make them promising alternatives for treating critical bone defects, especially in vulnerable patient groups.

Systematic literature review of in vivo rat femoral defect models using biomaterials to improve the induced membrane technique: a comprehensive analysis

Purpose

The aim of this study was to conduct a systematic literature review analyzing the results of in vivo rat femoral defect models using biomaterials for improving the induced membrane technique (IMT).

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the PubMed, Embase, and Web of Science databases were searched. Inclusion criteria were studies reporting results of the IMT in in vivo rat femoral critical-sized defect models using a biomaterial possibly combined with molecules. Methodologic quality was assessed with the Animal Research: Reporting In Vivo Experiments guidelines.

Results

Twenty studies met the inclusion criteria. Femoral stabilization with plate and screws was the most frequent. Histologic, biomechanical, and/or radiologic analyses were performed. In two-stage strategies, the PMMA spacer could be associated with bioactive molecules to enhance IM growth factor expression and improve bone formation. Modulating the roughness of spacers could increase IM thickness and accelerate its formation. In one-stage strategies, human tissue-derived membranes combined with bone grafting achieved bone formation comparable to a standard IMT. All calcium phosphate grafts seemed to require a functionalization with growth factors or bone marrow mononuclear cells to improve outcomes compared with non-functionalized grafts.

Conclusion

This systematic review described the main parameters of the in vivo rat femoral defect models using biomaterials to improve the induced membrane technique. Although the studies included had several methodological limitations that may limit the scope of these conclusions, one- and two-stage strategies reported promising results with biomaterials to improve the IMT.

Open Intra-articular Distal Femur Fracture with 21 cm Bone Loss Managed by Early Vascularized Fibula Grafting and Antibiotic Loaded Synthetic Calcium Sulfate Beads - A Case Report

Introduction

Open fractures with massive bone defect presents as challenging clinical scenario in clinical practice. If neglected, this can result in infection, non-union or severe limb length discrepancy. Autogenous vascularized fibula grafting along with stable fixation in the form of internal fixation is a viable option in such situations. Synthetic calcium sulfate is a suitable antibiotic carrier to deliver antibiotics locally to prevent infection. We report the case of an adult male who had an open fracture of the distal femur with segmental bone loss of 21 cm, managed with autogenous vascularized fibula graft and locking plates. We used antibiotic-loaded absorbable synthetic calcium sulfate beads locally during the procedure.

Case Report

A 52-year-old male, a known case of uncontrolled diabetes mellitus, presented to the emergency department with a comminuted open intra-articular fracture of the left distal femur with bone loss of 21 cm (arbeitsgemeinschaft fur osteosynthesefragen 33C3) following a road traffic accident. He was initially treated with meticulous debridement and internal fixation with locking compression plate. Considering the massive bone defect of 21 cm, he was planned for fibula grafting at a later stage. After 6 weeks, he underwent vascularized fibula grafting from opposite leg and an additional medial plate to stabilize the graft and augment the initial fixation. He was on regular follow-up in the outpatient department. The fracture united with no signs of infection or residual limb length discrepancy. At the latest follow-up at 7 months, he is walking independently without support and is having a functional range of knee movements. There were no post-operative complications in the right leg from where fibula was harvested.

Conclusion

Autogenous vascularized fibula graft together with a locking compression plate is a practical choice in managing open fractures with segmental bone loss. The high concentration of local antibiotic delivery with the help of synthetic calcium sulfate beads helped prevent infection, which is the most dreaded complication associated with open fractures. In addition, the calcium sulfate beads promote endochondral ossification resulting in early bone union.

A review of the Masquelet technique in the treatment of lower limb critical-size bone defects

The need for bone tissue to heal effectively is paramount given its role in the mechanical support of tissues. Bone has a very good natural healing potential in comparison with most other tissue types, largely regenerating to its pre-injury state in the vast majority of cases. Certain factors such as high energy trauma, tumour resection, revision surgery, developmental deformities and infection can lead to the formation of bone defects, where the intrinsic healing potential of bone is diminished owing to bone loss. Various approaches to resolving bone defects exist in current practice, each with their respective benefits and drawbacks. These include bone grafting, free tissue transfer, Ilizarov bone transport and the Masquelet induced membrane technique. This review focuses on evaluating the Masquelet technique, discussing its method and underlying mechanisms, the effectiveness of certain modifications, and its potential future directions.

[Biological reconstruction of large bone defects : Masquelet technique and new procedures]

Extensive diaphyseal and metaphyseal bone defects continue to pose a major challenge for orthopedic trauma surgeons. Various treatment options have been described for the biological reconstruction of these defects. The most frequently used methods are bone segment transport, the Masquelet technique and 3D printed scaffolds. As far as the Masquelet technique is concerned, in the first stage spacers, such as polymethyl methacrylate (PMMA), calcium sulfate or polypropylene are inserted into the bone defects to induce a foreign body membrane. In the second stage the bone defect surrounded by the induced membrane is filled with autologous cancellous bone. The time interval between the first and second interventions is usually 4-8 weeks whereby the induced membranes do not lose their bioactivity even with a latency period longer than 8 weeks. Three-dimensional printed scaffolds are increasingly used but large clinical studies are lacking in order to show the exact role of this procedure in the reconstruction of bone defects.

The antibiotics supplemented bone cement improved the masquelet's induced membrane in a rat femur critical size defect model

BACKGROUND

Masquelet technique is a two-stage surgical procedure used in the treatment of critical-size bone defects (CSD). Adding antibiotics to polymethylmethacrylate (PMMA) is still questionable to create higher quality induced membrane (IM). The aim of the study was to evaluate the effects of three antibiotic-supplemented cement, fusidic acid, teicoplanin, and gentamicin, on osteogenesis and IM progression applied to rat femur CSD model by comparing histopathological, biochemical, and immunohistochemical findings.

METHODS

Twenty-eight male rats were divided into four groups control, gentamicin (G), teicoplanin (T), and fusidic acid (FA). A 10 mm CSD was created in rat femurs. In the postoperative 4th week, intracardiac blood samples were collected for biochemical analysis of bone alkaline phosphatase (BALP), osteocalcin (OC), and tumor necrosis factor-alpha (TNF-α) levels. IMs obtained in secondary operation were fixed and prepared for histopathological scoring of membrane progression and immunohistochemical evaluation of rat-specific Transforming Growth Factor-Beta (TGF-β), Runt-related Transcription Factor 2 (Runx2), and Vascular Endothelial Growth Factor (VEGF) expressions.

RESULTS

Levels of BALP and OC in serum didn't change among groups significantly while serum TNF-α levels significantly decreased in all antibiotic groups compared to the control group (P = 0.017). Histological scores of groups FA and T were significantly higher than those of groups Control and G (P = 0.0007). IMs of groups T and FA showed good progression while those of groups Control and G were also moderately progressed. A significant increase in TGF-β expression was observed in group G and FA (P = 0.001) while a significant increase in the expression of VEGF was observed in groups G and T compared to the control group (P = 0.036).

CONCLUSIONS

The bone cement impregnated with thermostable and safe antibiotics, gentamicin, fusidic acid, and teicoplanin can increase osteogenesis and support IM progression by increasing the expressions of TGF-β and VEGF. Anabolic effects of induced membranes used in the treatment of critical-size bone defects can be enhanced by antibiotic-supplemented PMMAs applied by altering the original technique.

Antibiotic-impregnated calcium sulfate for the treatment of pediatric hematogenous osteomyelitis

BACKGROUND

Antibiotic-impregnated calcium sulfate has excellent curative efficacy in chronic osteomyelitis. However, its curative efficacy in pediatric hematogenous osteomyelitis has not been sufficiently studied. The purpose of this study was to evaluate the curative effects of antibiotic-impregnated calcium sulfate in the treatment of pediatric hematogenous osteomyelitis.

METHODS

Overall, twenty-one pediatric patients with hematogenous osteomyelitis treated at our hospital between 2013 and 2018 were included for assessment. The clinical history, clinical manifestation, infection recurrence rate, sinus leakage, incision leakage, pathological fractures, bone growth and surgical procedures were analyzed.

RESULTS

The infection recurrence rate was 0% (0/21) at a minimum of 31 months (range 31 to 91 months) of follow-up. Postoperative incision leakage was found in one pediatric patient. Osteolysis was found in one pediatric patient. Acceleration of bone growth occurred in one pediatric patient. Retardation of bone growth occurred in one pediatric patient. Genu valgus deformity occurred in one pediatric patient.

CONCLUSIONS

Although noninfectious complications occurred, the curative effect of antibiotic-impregnated calcium sulfate in pediatric hematogenous osteomyelitis was satisfactory.

New bone formation using antibiotic-loaded calcium sulfate beads in bone transports for the treatment of long-bone osteomyelitis

PURPOSE

Bone transport is one of the most frequently used techniques for critical-sized bone defects due to trauma or infection. To fill the defect area and avoid the collapse of soft tissues during transport, some authors have described the use of polymethylmethacrylate or absorbable antibiotic carriers in the form of cylindrical blocks.

METHODS

In this article, we present our experience in the treatment of post-traumatic osteomyelitis of the lower and upper limbs, using a bone transport technique with antibiotic-loaded calcium sulfate in the form of beads. Results With the progressive absorption of calcium sulfate, we observed the formation of a bone-like tissue envelope at the periphery of the defect area. Histological analysis and direct visualization during open revision surgery of the docking site in all patients confirmed the presence of newly formed bone tissue with a high presence of osteoblasts and few osteoclasts; no areas of necrosis or signs of infection were observed. This bone envelope maintained the mechanical protective function of the transport path and docking site, and also provided a biological stimulus to avoid the development of necrotic areas and optimize the consolidation phase. Conclusion Bone transport with calcium sulfate beads improves biological and mechanical support and reduces the number of surgeries required.

Influence of the Immune Microenvironment Provided by Implanted Biomaterials on the Biological Properties of Masquelet-Induced Membranes in Rats: Metakaolin as an Alternative Spacer

Macrophages play a key role in the inflammatory phase of wound repair and foreign body reactions-two important processes in the Masquelet-induced membrane technique for extremity reconstruction. The macrophage response depends largely on the nature of the biomaterials implanted. However, little is known about the influence of the macrophage microenvironment on the osteogenic properties of the induced membrane or subsequent bone regeneration. We used metakaolin, an immunogenic material, as an alternative spacer to standard polymethylmethacrylate (PMMA) in a Masquelet model in rats. Four weeks after implantation, the PMMA- and metakaolin-induced membranes were harvested, and their osteogenic properties and macrophage microenvironments were investigated by histology, immunohistochemistry, mass spectroscopy and gene expression analysis. The metakaolin spacer induced membranes with higher levels of two potent pro-osteogenic factors, transforming growth factor-β (TGF-β) and bone morphogenic protein-2 (BMP-2). These alternative membranes thus had greater osteogenic activity, which was accompanied by a significant expansion of the total macrophage population, including both the M1-like and M2-like subtypes. Microcomputed tomographic analysis showed that metakaolin-induced membranes supported bone regeneration more effectively than PMMA-induced membranes through better callus properties (+58%), although this difference was not significant. This study provides the first evidence of the influence of the immune microenvironment on the osteogenic properties of the induced membranes.

Repairing tendon-exposed wounds by combing the Masquelet technique with dermoplasty

BACKGROUND

Wound repair is a new field that has emerged in China in the last 5 years. Exposed tendon wounds are one of the most common problems faced in wound treatment today, as the poor blood supply leads to low survival rates of skin grafts. This paper explores the feasibility of applying the Masquelet technique to repair tendon-exposed wounds.

METHOD

We examined 12 patients with tendon-exposed wounds, 5 males and 7 females, from January 2021 to November 2021, including 2 patients with post-traumatic wounds, 8 diabetic patients with dorsal wounds, and 2 patients with various chronic infections. The Masquelet technique was employed to treat these wounds. The wound surface was sealed with antibiotic bone cement to form an induction membrane, the cement was removed after 3-4 weeks, and the wound was repaired with skin grafts to observe survival, appearance, texture, healing, and related functions.

RESULTS

All wounds were covered with antibiotic bone cement, and after 3-4 weeks, an induction membrane was applied, and in 10 out of 12 patients, full-thickness skin grafts were applied, and the patients survived. However, in 2 patients, the skin became partially necrotic, but these patients recovered by changing medications.

CONCLUSION

The current study found that direct skin grafting may effectively treat exposed tendon wounds once the Masquelet approach generates the induction membrane. Further, this method is less difficult, less expensive, and easier to care for the procedure that deserves to be used more frequently.

Masquelet technique in military practice: specificities and future directions for combat-related bone defect reconstruction

Because of its simplicity, reliability, and replicability, the Masquelet induced membrane technique (IMT) has become one of the preferred methods for critical bone defect reconstruction in extremities. Although it is now used worldwide, few studies have been published about IMT in military practice. Bone reconstruction is particularly challenging in this context of care due to extensive soft-tissue injury, early wound infection, and even delayed management in austere conditions. Based on our clinical expertise, recent research, and a literature analysis, this narrative review provides an overview of the IMT application to combat-related bone defects. It presents technical specificities and future developments aiming to optimize IMT outcomes, including for the management of massive multi-tissue defects or bone reconstruction performed in the field with limited resources.

Bone defect treatment: does the type and properties of the spacer affect the induction of Masquelet membrane? Evidence today

PURPOSE

High clinical success rates have been reported with the Masquelet technique in the treatment of traumatic bone loss. An increasing number of studies suggest that various factors can influence the properties of induced membranes. Goal of this systematic review is to answer the following questions: (1) which are the ideal spacer properties (material, surface topography, antibiotic supplementation) to booster the quality and osteogenic potential of induced membranes? (2) what is the ideal time to perform the second-stage operation?

METHODS

A systematic search using the keywords "((Masquelet) OR (Induced Periosteum)) AND ((Spacer) OR (Time))" was performed in PubMed, Embase and Cochrane Library according to PRISMA guidelines. Studies published up to the 23rd of February 2022 were included and assessed independently by two reviewers.

RESULTS

Thirteen animal and 1 clinical studies were identified to address the above questions. Spacer materials used were PMMA, silicone, titanium, polypropylene, PVA, PCL and calcium sulfate. With the exception of PVA sponges, all solid materials could induce membranes. Low union rates have been reported with titanium and rough surfaced spacers. Scraping of the inner surface of the IM also increased bony union rates. In terms of the ideal timing to perform the second-stage evidence suggests that membranes older than 8 weeks continue to have regenerative capacities similar to younger ones.

CONCLUSION

Membranes induced by smooth PMMA spacers loaded with low concentrations of antibiotics showed powerful osteogenic properties. Other materials such as Polypropylene or Calcium sulfate can also be used with good results. Despite current recommendation to perform the second stage operation in 4-8 weeks, membranes older than 8 weeks seem to have similar regenerative capacities to younger ones.

The induced membrane technique: Optimization of bone grafting in a rat model of segmental bone defect

INTRODUCTION

The induced membrane technique (IMT) is a two-stage surgical procedure used to treat fracture nonunion and bone defects. Although there is an increasing number of animal studies investigating the IMT, few have examined the outcomes of bone healing after a second stage grafting procedure. This study aimed at comparing two bone grafting procedures, as part of the IMT, in order to establish a rat model providing consistent healing outcomes.

METHODS

In male Fischer 344 rats, we created a 5 mm defect in the right femur, stabilized the bone with a plate and screws, and inserted a polymethylmethacrylate spacer into the defect. Four weeks later, the spacer was removed. Bone graft was harvested from a donor rat and placed into the defect, followed by membrane and wound closure. Experiments were conducted in two groups. In group 1 (n = 11), the bone graft contained a variable amount of cortical and cancellous bone, the time from donor euthanasia to grafting was up to 240 min, and one donor rat provided graft for 5-6 recipients. In group 2 (n = 12), we reduced the contribution of cortical bone to the graft, included bone marrow, and kept donor euthanasia to grafting time under 150 min. One donor was used per 3-4 recipients. The volume of graft per recipient and all other elements of the protocol were the same across groups. Bone healing at 12 weeks post grafting was compared radiographically by two orthopaedic surgeons in a blinded fashion, based on union status and a modified Lane & Sandhu score.

RESULTS

Healing rates improved from 36.4% in Group 1 to 91.6% in Group 2. There was a significant relationship between the methods and resulting union status (p = 0.004). The odds of achieving full union were significantly higher in group 2 compared to group 1 (odds ratio=19.25, 95% confidence interval [1.77-209.55]; p = 0.009). The average radiographic score was also significantly higher in group 2 (p = 0.005).

CONCLUSION

The revised bone grafting method significantly improved the healing outcomes and contributed to establishing a consistent rat model of the IMT. This model can benefit preclinical investigations by allowing for reliable and clinically-relevant comparisons.

Probing the role of methyl methacrylate release from spacer materials in induced membrane bone healing

In the induced membrane (IM) technique for bone reconstruction, a poly(methyl methacrylate) (PMMA) spacer is implanted to induce formation of a foreign body membrane around the defect site. Membrane development is essential for later bone grafting success, yet the mechanism by which the IM promotes bone regeneration remains unknown, as are the ways that spacer composition plays a role in the membrane's healing potential. This study investigated the impact of leached methyl methacrylate (MMA)-the major monomeric component of PMMA-on IM development. In vitro cell culture found that MMA elution did not impact endothelial cell or mesenchymal stem cell proliferation. For in vivo analysis, we advanced a streamlined rat femoral model to efficiently study the influence of spacer properties on IM characteristics. Comparison of membrane formation around polycaprolactone (PCL), MMA-eluting PCL (high-dose PCL-MMA and low-dose PCL-MMA), and surgical PMMA revealed robust membranes enveloped all groups after 4 weeks in vivo, with elevated expression of osteogenic bone morphogenetic protein-2 and angiogenic vascular endothelial growth factor compared with the surrounding muscle and bone tissues. Growth factor quantitation in IM tissue found no statistically significant difference between groups. New bone growth, vascularization, and CD163+ macrophage populations surrounding the polymer implants were also quantified; and blood vessel formation around high-dose PCL-MMA was found to be significantly decreased compared with PCL alone. To the best of our knowledge, these findings represent the first time that results have been obtained about the characteristics of membranes formed around PCL in the IM setting.

The induced membrane technique in animal models: a systematic review

Objectives:

Data Sources:

Study Selection:

Data Extraction:

Data Synthesis:

Conclusions:

The Masquelet Technique: Can Disposable Polypropylene Syringes be an Alternative to Standard PMMA Spacers? A Rat Bone Defect Model

BACKGROUND

Usually, the two-stage Masquelet induced-membrane technique for extremity reconstruction begins with a polymethylmethacrylate (PMMA) cement spacer-driven membrane, followed by an autologous cancellous bone graft implanted into the membrane cavity to promote healing of large bone defects. In exceptional cases, spacers made of polypropylene disposable syringes were successfully used instead of the usual PMMA spacers because of a PMMA cement shortage caused by a lack of resources. However, this approach lacks clinical evidence and requires experimental validation before being recommended as an alternative to the conventional technique.

QUESTIONS/PURPOSES

To (1) develop and (2) validate a critical-sized femoral defect model in rats for two stages of the Masquelet technique and to (3) compare the biological and bone healing properties of polypropylene-induced membranes and PMMA-induced membranes in this model.

METHODS

Fifty male Sprague Dawley rats aged 8 weeks old received a 6-mm femur defect, which was stabilized with an external fixator that was converted into an internal device. In the development phase, the defect was filled with PMMA in 16 rats to determine the most favorable timing for bone grafting. Two rats were excluded since they died of anesthetic complications. The other 14 were successively euthanized after 2 weeks (n = 3), 4 weeks (n = 4), 6 weeks (n = 4), and 8 weeks (n = 3) for induced membrane analyses. In the validation phase, 12 rats underwent both stages of the procedure using a PMMA spacer and were randomly assigned to two groups, whether the induced membrane was preserved or removed before grafting. To address our final objective, we implanted either polypropylene or PMMA spacers into the defect (Masquelet technique Stage 1; n = 11 rats per group) for the period established by the development phase. In each group, 6 of 11 rats were euthanized to compare the biological properties of polypropylene-induced membranes and PMMA-induced membranes using histological qualitative analysis, semiquantitative assessment of the bone morphogenic protein-2 content by immunostaining, and qualitative assessment of the mesenchymal stromal cell (MSC; CD31-, CD45-, CD90+, and CD73+ phenotypes) content by flow cytometry. Quantitative measurements from serum bone turnover markers were also performed. The five remaining rats of each group were used for Masquelet technique Stage 2, in which rat bone allografts were implanted in the induced membrane cavity after the polypropylene or PMMA spacers were removed. These rats recovered for 10 weeks before being euthanized for microCT quantitative measurements and bone histology qualitative assessment to evaluate and compare the extent of bone regeneration between groups.

RESULTS

Induced membrane analyses together with serum bone turnover measurements indicated that a 4-week interval time between stages was the most favorable. Removal of the induced membrane before grafting led to almost constant early implant failures with poor bone formation. Four-week-old rats with polypropylene-triggered induced membranes displayed similar histologic organization as rats with PMMA-driven induced membranes, without any difference in the cell density of the extracellular matrix (4933 ± 916 cells per mm2 for polypropylene versus 4923 ± 1284 cells per mm2 for PMMA; p = 0.98). Induced membrane-derived MSCs were found in both groups with no difference (4 of 5 with polypropylene versus 3 of 3 with PMMA; p > 0.99). Induced membrane bone morphogenic protein-2 immunolabeling and serum bone turnover marker levels were comparable between the polypropylene and PMMA groups. MicroCT analysis found that bone regeneration in the polypropylene group seemed comparable with that in the PMMA group (29 ± 26 mm3 for polypropylene versus 24 ± 18 mm3 for PMMA; p > 0.99). Finally, qualitative histological assessment revealed a satisfactory endochondral ossification maturation in both groups.

CONCLUSION

Using a critical-sized femoral defect model in rats, we demonstrated that polypropylene spacers could induce membrane encapsulation with histologic characteristics and bone regenerative capacities that seem like those of PMMA spacers.

CLINICAL RELEVANCE

In a same bone site, polymers with close physical properties seem to lead to similar foreign body reactions and induce encapsulating membranes with comparable bone healing properties. Polypropylene spacers made from disposable syringes could be a valuable alternative to PMMA. These results support the possibility of a cementless Masquelet technique in cases of PMMA shortage caused by a lack of resources.

The Basic Science Behind the Clinical Success of the Induced Membrane Technique for Critical-Sized Bone Defects

»

The induced membrane technique (IMT) takes advantage of an osteoinductive environment that is created by the placement of a cement spacer into a bone defect.

»

Most commonly, a polymethylmethacrylate (PMMA) spacer has been used, but spacers made from other materials have emerged and achieved good clinical outcomes.

»

The IMT has demonstrated good results for long-bone repair; however, more research is required in order to optimize union rates as well as delineate more precise indications and surgical timing.

Masquelet's induced membrane technique: Review of current concepts and future directions

Masquelet's induced membrane technique (MIMT) is a relatively new, two-stage surgical procedure to reconstruct segmental bone defects. First performed by Dr. Masquelet in the mid-1980s, MIMT has shown great promise to revolutionize critical-sized bone defect repair and has several advantages over its alternative, distraction osteogenesis (DO). Also, its success in extremely challenging cases (defects > 15 cm) suggests that its study could lead to discovery of novel biological mechanisms that might be at play during segmental defect healing and fracture non-union. MIMT's advantages over DO have led to a world-wide increase in MIMT procedures over the past decades. However, MIMT often needs to be repeated and so the average initial success rate in adults lags significantly behind that of DO (86% vs 95%, respectively). The autologous foreign-body membrane created during the first stage by the immune system's response to a polymethyl methacrylate bone cement spacer is critical to supporting the morselized bone graft implanted in the second stage. However, the biological and/or physical mechanisms by which the membrane supports graft to bone union are unclear. This lack of knowledge makes refining MIMT and improving the success rates through technique improvements and patient selection a significant challenge and hinders wider adoption. In this review, current knowledge from basic, translational, and clinical studies is summarized. The dynamics of both stages under normal conditions as well as with drug or material perturbations is discussed along with perspectives on high-priority future research directions.

Enhanced mechanical and biological performances of CaO-MgO-SiO2 glass-ceramics via the modulation of glass and ceramic phases

This work reports a new CaO-MgO-SiO₂ (CMS) bioactive glass-ceramic, using ZrO₂ as a nucleus to modulate the ratios of glass and ceramic phases as a function of sintering temperature. Mg-rich bioactive CMS glass-ceramics exhibit advantages regarding mechanical strength (flexural strength ~190 MPa and compressive strength ~555 MPa), in-vitro and in-vivo biocompatibilities, and bone ingrowth. The high mechanical strengths could be attributed to the CaMgSi₂O₆ glass-ceramic and lower porosity. X-ray absorption spectra indicate an increased SiO covalent bond via the development of CaMgSi₂O₆ glass-ceramics. From the in-vitro cytotoxicity and BMSC differentiation assays, the CMS samples sintered above 800 °C exhibited better cell attachment and differentiation, possibly due to structural stability, appropriate pore, and ion release to boost osteogenesis. Compared to hydroxyapatite (HA) ceramics, the CMS glass-ceramics display higher mechanical strengths, biocompatibility, and osteoconductivity. An in-vivo experiment demonstrated a fine bone-ingrowth profile around the CMS implant. This study may further the application of CMS glass-ceramics in bone implants.

Effects of topical mechanical stability on the formation of Masquelet membrane in a rabbit radial defect model

The exact mechanism of Masquelet technique is unknown. This study intends to explore the effects of topical mechanical stability on the formation of Masquelet membrane. Segmental radius shaft defect was created in all rabbits, which were filled with polymethylmethacrylate (PMMA) in Non-fixation group, and with PMMA fixed with plates in Fixation group, and subjected to no disposal in control group. The topical stability of PMMA and plates were monitored via X-ray and mechanical test. And the membranes were excised for further Histological, IHC and Western-Blotting analysis 4 and 6 weeks post-operatively. X-ray revealed no sign of plates loosening, or shift of PMMA. Mechanical tests revealed superior topical stability by plates. Pathological examinations suggested that vascularized and osteogenic membranes were formed around PMMA. IHC and Western-Blotting analysis revealed that both Fixation and Non-fixation group exerted significant effects on the expression of Ki67, COL I, and CD31 positive cells, as well as the protein expression of osteogenic (RUNX2, ALP) and angiogenic (VEGFA, TGF-β1) factors. And compared with membrane in Non-fixation group, Fixing PMMA spacer with plates caused a significant increase in osteogenic and angiogenic expression. This study indicates that rigid fixation provided by plate in Masquelet technique positively alters the quality of membrane formed surrounding PMMA, in terms of significantly osteogenic and angiogenic potential.

The Masquelet technique: Current concepts, animal models, and perspectives

Bone reconstruction within a critical-sized defect remains a real challenge in orthopedic surgery. The Masquelet technique is an innovative, two-step therapeutic approach for bone reconstruction in which the placement of a poly (methylmethacrylate) spacer into the bone defect induces the neo-formation of a tissue called "induced membrane." This surgical technique has many advantages and is often preferred to a vascularized bone flap or Ilizarov's technique. Although the Masquelet technique has achieved high clinical success rates since its development by Alain-Charles Masquelet in the early 2000s, very little is known about how the process works, and few animal models of membrane induction have been developed. Our successful use of this technique in the clinic and our interest in the mechanisms of tissue regeneration (notably bone regeneration) prompted us to develop a surgical model of the Masquelet technique in rats. Here, we provide a comprehensive review of the literature on animal models of membrane induction, encompassing the defect site, the surgical procedure, and the histologic and osteogenic properties of the induced membrane. We also discuss the advantages and disadvantages of those models to facilitate efforts in characterizing the complex biological mechanisms that underlie membrane induction.