Chest wall reconstruction with two types of biodegradable polymer prostheses in dogs

In vitro comparison of biological and synthetic materials for skeletal chest wall reconstruction

BACKGROUND

Various biological and synthetic materials have been proposed for use in skeletal chest wall reconstruction (SCWR). Because of the lack of studies allowing a direct comparison of SCWR materials, their clinical use often depends on the surgeon's preference and experience. The aim of this study was to analyze 6 synthetic and 3 biological materials frequently used in SCWR with respect to their cytotoxicity, bacterial adhesion, surface characteristics, and mechanical properties to facilitate data-driven decisions.

METHODS

The effect of the SCWR materials and their extracts on the metabolism of human skeletal muscle cells (SkMCs), dermal fibroblasts, adipose cells, and osteoblasts was analyzed in vitro. Bacterial adhesion was quantified by incubating samples in bacterial suspensions (Staphylococcus epidermidis, S aureus, and Escherichia coli), followed by counting colony-forming units and performing scanning electron microscopy. Moreover, the mechanical properties of the materials were analyzed under uniaxial tensile loading to failure.

RESULTS

The metabolism of all cell types seeded on the SCWR materials was reduced compared with untreated cells. With the exception of Vypro (Ethicon, Somerville, NJ), whose extracts significantly reduced fibroblast viability, no cytotoxic leachable substances were detected. Biological materials were less cytotoxic compared with synthetic ones, but they demonstrated increased bacterial adhesion. Synthetic materials demonstrated higher elongation to failure than did biological materials.

CONCLUSIONS

Biological and synthetic SCWR materials showed significant differences in their cytotoxicity, bacterial adhesion, and biomechanical properties, suggesting that they may be used for different indications in SCWR. Further comparable in vivo studies are needed to analyze their performance in different indications of clinical application.

A rigid and bioabsorbable material for anterior chest wall reconstruction in a canine model

OBJECTIVES

The optimal material for anterior chest wall reconstruction following chest wall resection remains controversial. The aim of this experimental study was to evaluate short-term, morphological and histological outcomes of anterior chest wall reconstruction with a rigid and bioabsorbable material in a canine model.

METHODS

Twenty adult beagle dogs underwent anterior chest wall resection. In the experimental group (n = 10), the anterior chest wall was reconstructed with a rigid and bioabsorbable material composed of poly-L-lactide acid matrix (60 wt%) and uncalcined and unsintered hydroxyapatite particles (40 wt%), whereas in the control group it was (n = 10) reconstructed with dual polypropylene mesh sheets. Short-term complication rates were compared with a χ(2) test. Postoperative sternal deviations were evaluated with sternal alignment angles using computed tomography and multiplanar reconstruction and were compared with Mann-Whitney U-test immediately after reconstruction, and at 1, 3, 6, 9 and 12 months postoperatively. Histological findings of the regenerated chest wall tissue were obtained after staining with haematoxylin and eosin and Elastica van Gieson (EVG) and compared at 3, 6, 9 and 12 months.

RESULTS

There was not a significant difference in the short-term postoperative complication rate (P = 0.53) and the complication rate was 20% (wound infection, n = 1 and lethal mediastinitis, n = 1) in the control group and 10% (wound infection, n = 1) in the experimental group. The postoperative sternal deviation was significantly less remarkable at 1 month (123.3 ± 32.2° vs 159.4 ± 19.7°, P = 0.027), 3 months (109.8 ± 34.7° vs 150.9 ± 34.2°, P = 0.039) and 12 months (61 ± 15.6° vs 170.3 ± 6.6°, P = 0.046) in the experimental group than in the control group, whereas no significant difference was noted immediately after reconstruction (165.7 ± 6.4° vs 168.4 ± 9.1°, P = 0.50). Histological findings showed dense connective tissue in the regenerated chest wall in both groups and showed chondroblasts in the regenerated chest wall tissue at 3 and 6 months only in the experimental group.

CONCLUSIONS

Our results suggest that anterior chest wall reconstruction with a rigid and bioabsorbable material is feasible and may be a valuable alternative to reconstruction with a non-rigid and non-absorbable material.

Properties of novel composite meshes in chest wall reconstruction: A comparative animal study

PURPOSE

Novel composite meshes routinely used in laparoscopic hernia repair reportedly lead to fewer and less dense visceral adhesions and may provide a viable alternative in thoracic surgery as well.

METHODS

A total of 15 adult domestic pigs underwent full thickness chest wall resection and reconstruction with Parietene (polypropylene composite; PTE, n = 5), Parietex (polyester composite; PTX, n = 5) or Bard (purely polypropylene, n = 5) mesh. After an observation period of 90 days all animals were sacrificed, intrathoracic adhesions classified via thoracoscopy (VATS), meshes explanted and peak peal strength required for lung/mesh separation recorded.

RESULTS

Adhesions assessed through VATS-exploration were strongest in the PTX-Group while PTE and BM showed comparable results. Tensiometric analyses of peak peal strength confirmed lower values in BM than for PTE and PTX. Both composite materials showed good overall bioincorporation with post-surgical perigraft-fibrosis being strongest in BM.

CONCLUSION

We consider composite grafts a suitable alternative for chest wall reconstruction. They are characterized by good overall biointegration and limited perigraft-fibrosis, thus potentially facilitating redo-procedures, even though a hydrophilic coating per se does not appear to prevent intrathoracic adhesion formation.

Reconstruction of large-size abdominal wall defect using biodegradable poly-p-dioxanone mesh: an experimental canine study

BACKGROUND

Reconstruction of large-size abdominal wall defect (AWDs) is a huge challenge faced in current surgical practice. In this study, we aimed to evaluate the effectiveness and safety of biodegradable poly-p-dioxanone (PDO) mesh for reconstructing large-size AWDs in an experimental canine model.

METHODS

Eighteen experimental canines were randomly and equally divided into three groups, namely, a PDO group, a Marlex group and a control group (n = 6 each). Following the creation of a 6 cm × 5.5 cm AWD, PDO mesh and Marlex mesh were used to reconstruct the defect in the PDO and Marlex groups, respectively. The defect was closed using relaxation sutures alone in the control group. Animals were killed 24 weeks after surgery, and reconstruction outcomes were evaluated using radiography, histology and biomechanical testing.

RESULTS

All animals except those in the control group survived the experiment. The PDO group showed no wound dehiscence, herniation or infection, whereas the animals in the Marlex group exhibited marked foreign body reactions. The PDO group had less intraabdominal adhesion than the Marlex group. As shown by radiography, histology and biomechanical testing, PDO mesh exhibited complete degradation and favorable biochemical strength at 24 weeks postsurgery.

CONCLUSIONS

PDO mesh implantation is an effective, safe treatment modality for reconstructing large-size AWDs.

Single-stage repair of the anterior chest wall following sternal destruction complicated by mediastinitis

PURPOSE

Although various techniques have been described, the ideal reconstructive procedure for treating massive sternal fragmentation and necrosis is still a matter of debate. Sometimes, reconstruction is so challenging that repetitive operations are required, particularly when complicated by mediastinitis and sternal osteomyelitis.

METHODS

Five patients (three males, two females, median age 66) with severe osteomyelitis and sternal destruction after receiving myocardial revascularization underwent partial or radical sternal resection, omental flap transposition, titanium mesh implantation and rectus abdominis muscle flap transposition. The final procedure involved single-stage closure.

RESULTS

One patient died 9 days after the final procedure due to pneumonia and septicemia. The other patients received antibiotics for at least 6 weeks postoperatively. The mean hospital stay was 36 days. Optimal wound healing was observed, with acceptable cosmetic disorders.

CONCLUSIONS

Although lateral sternal support is the first-line surgical treatment for sternal dehiscence, performing primary closure of complicated defects is often impossible. Aggressive treatment modalities are required in such cases for anterior chest wall defects. This technique provides the ability to perform rigid and stable sternal closure in complicated cases.

Tissue engineering rib with the incorporation of biodegradable polymer cage and BMSCs/decalcified bone: an experimental study in a canine model

Background

The reconstruction of large bone defects, including rib defects, remains a challenge for surgeons. In this study, we used biodegradable polydioxanone (PDO) cages to tissue engineer ribs for the reconstruction of 4cm-long costal defects.

Methods

PDO sutures were used to weave 6cm long and 1cm diameter cages. Demineralized bone matrix (DBM) which is a xenograft was molded into cuboids and seeded with second passage bone marrow mesenchymal stem cells (BMSCs) that had been osteogenically induced. Two DBM cuboids seeded with BMSCs were put into the PDO cage and used to reconstruct the costal defects. Radiographic examination including 3D reconstruction, histologic examination and mechanical test was performed after 24 postoperative weeks.

Results

All the experimental subjects survived. In all groups, the PDO cage had completely degraded after 24 weeks and been replaced by fibrous tissue. Better shape and radian were achieved in PDO cages filled with DBM and BMSCs than in the other two groups (cages alone, or cages filled with acellular DBM cuboids). When the repaired ribs were subjected to an outer force, the ribs in the PDO cage/DBMs/BMSCs group kept their original shape while ribs in the other two groups deformed. In the PDO cage/DBMs/BMSCs groups, we also observed bony union at all the construct interfaces while there was no bony union observed in the other two groups. This result was also confirmed by radiographic and histologic examination.

Conclusions

This study demonstrates that biodegradable PDO cage in combination with two short BMSCs/DBM cuboids can repair large rib defects. The satisfactory repair rate suggests that this might be a feasible approach for large bone repair.

Animal experimental study of the fully biodegradable atrial septal defect (ASD) occluder

This study was conducted to evaluate the feasibility, safety, biocompatibility, and degradation features of a fully biodegradable occluder for closure of atrial septal defect (ASD) in an acute canine model. The ASD was created in 20 healthy mongrel dogs by the brockenbrough needle, and the fully biodegradable occluders were implanted by self-made delivery system. The success rate and complications were observed. Acute ASD models were successfully created in 18 dogs, and 16 occluders were successfully implanted in the ASD models. Animals were sacrificed at different times after procedure. The cardiac gross anatomy showed that all occluders were stable in the interatrial septum, no vegetation or thrombus formation was observed on the surface of all occluders. They were embedded into endogenous host tissue gradually at 12-week follow-up. Different periods of pathological observations suggested that the occluders degraded gradually over about 24 weeks and essentially became an integral part of the septum. Transcatheter closure of ASD in acute canine model using the fully biodegradable ASD occluder has the potential of a high successful rate of technique, excellent biocompatibility, and fewer complications with adequate, immediate, and short-term results.

Chest wall resection and reconstruction according to the principles of biomimesis

Biomimesis has become the objective of the reconstructive strategies after chest wall resections for primary or secondary tumors. Biomimesis is pursued by respecting the anatomy, preserving function, selecting adequate reconstructive materials, and integrating multidisciplinary efforts for complex reconstructions. Elements of novelty in the clinical practice are represented by the introduction of the principles of video-assisted thoracic surgery to resect chest wall tumors and the increasingly frequent resort to either new materials or revised concepts of time-honored ones for chest wall reconstruction. Experimental investigation seems to outline interesting perspectives for materials destined to reconstruction after either partial or full-thickness resections for recurrent chest wall tumors.

Sternum resection and chest wall reconstruction with metaacrilate implant in tuberculosis

We report a case of successful sternum and ribs/cartilage resection and chest wall reconstruction with a methacrylate implant produced using a three-dimensional model in a patient with a tuberculotic mass in this region. Clinical and radiologic follow-up 2 years after surgery showed excellent cosmetic and functional outcome.

Overview on current and future materials for chest wall reconstruction

This article focuses on new materials available to thoracic surgeons for the reconstruction of chest wall defects. Each surgeon is called to select the best reconstructive strategy based on the disease for which the resection is needed, the possible extension to adjacent structures, the availability of professional colleagues for multidisciplinary involvement, and the preferred (or available) material for full or partial thickness reconstruction.