Microvascular vastus lateralis muscle flap for chronic empyema associated with a large cavity

bmp-2 Gene-Transferred Skeletal Muscles with Needle-Type Electrodes as Efficient and Reliable Biomaterials for Bone Regeneration

BACKGROUND

Bone morphogenetic protein-2 (bmp-2) has a high potential to induce bone tissue formation in skeletal muscles. We developed a bone induction system in skeletal muscles using the bmp-2 gene through in vivo electroporation. Natural bone tissues with skeletal muscles can be considered potential candidates for biomaterials. However, our previous system using plate-type electrodes did not achieve a 100% success rate in inducing bone tissues in skeletal muscles. In this study, we aimed to enhance the efficiency of bone tissue formation in skeletal muscles by using a non-viral bmp-2 gene expression plasmid vector (pCAGGS-bmp-2) and needle-type electrodes.

METHODS

We injected the bmp-2 gene with pCAGGS-bmp-2 into the skeletal muscles of rats' legs and immediately placed needle-type electrodes there. Skeletal tissues were then observed on the 21st day after gene transfer using soft X-ray and histological analyses.

RESULTS

The use of needle-type electrodes resulted in a 100% success rate in inducing bone tissues in skeletal muscles. In contrast, the plate-type electrodes only exhibited a 33% success rate. Thus, needle-type electrodes can be more efficient and reliable for transferring the bmp-2 gene to skeletal muscles, making them potential biomaterials for repairing bone defects.

The free vastus lateralis muscle flap. A smart less used flap for soft tissue reconstruction of the weight-bearing foot

BACKGROUND

The lateral circumflex femoral artery one of the most favoured donor-site for a wide array of free flaps including either cutaneous, fascial and muscle components or a combination thereof. Here, we provide evidence on the safe use of the free vastus lateralis muscle flap and its feasibility for optimal soft tissue coverage of the weight-bearing foot.

METHODS

Eighteen consecutive patients with soft tissue defects of the heel (n = 3, 16.6%) and plantar aspect of the mid- and forefoot (n = 15, 83.3%) of either post traumatic (n = 10), diabetic (n = 6) or ischemic (n = 2) etiology, received nineteen free vastus lateralis muscle free flaps covered with split-thickness skin grafts. The postoperative results in terms of wound healing, weight-bearing function, patient satisfaction were evaluated. In patients with chronic conditions (n = 8) the AOFAS (American Orthopaedic Foot and Ankle Society) scoring system was used preoperatively and 6 months postoperatively for evaluation of reconstruction outcomes.

RESULTS

All flaps survived. Their complete anatomical integration allowed regaining normal walking in all patients. In five patients, partial loss of the skin graft which either healed spontaneously or necessitated a redo skin grafting was noted. One patient developed a late flap-skin interface ulcer, which was solved by primary excision and direct closure. Compared with the preoperative values, the mean AOFAS score in the evaluated patients (n = 8) improved significantly (34.13 vs. 77.63, p < 0.001).

CONCLUSION

The skin-grafted free vastus lateralis muscle flap can safely be used as a "smart" tool for coverage of weight-bearing foot providing optimal cushioning and functional results without fearing donor-side morbidity.

The effect of BMP-7 gene activated muscle tissue implants on the repair of large segmental bone defects

BACKGROUND

This study was conducted in order to investigate the effect of Bone Morphogenetic Protein-7 (BMP-7) transduced muscle cells on bone formation and to further develop an innovative abbreviated ex vivo gene therapy for bone repair. As conventional ex vivo gene therapy methods require an elaborative and time-consuming extraction and expansion of cells we evaluated an expedited approach. Fragments of muscle tissue were directly activated by BMP-7 cDNA and implanted into bone defects.

METHODS

25 male, syngeneic Fischer 344 rats were used in the present study. Muscle tissue was harvested from two donor rats and either transduced with an adenovirus carrying the BMP-7 cDNA or remained unmodified. 5mm osseous defects in the right femora of 23 rats were treated with either unmodified muscle tissue (control group) or BMP-7 activated muscle tissue (treatment group). Six weeks after surgery, rat femora were evaluated by radiographs, micro-computed tomography (μCT) and histology.

RESULTS

Implantation of BMP-7 activated muscle grafts led to bony bridging in 5 out of 12 defects (41.7%) and to bone formation without bridging in 2 out of 12 defects. In 2 femoral defects of this group radiographs, μCT-imaging and histology did not reveal significant mineralization. Three animals of the BMP-7 treatment group had to be euthanized due to serious wound infection. The bone volume of the treatment group was significantly (p=0.007) higher compared to the control group.

CONCLUSION

This study shows that BMP-7 gene activated muscle fragments have the potential to regenerate critical-size segmental bone defects in rats. However, further development of this promising expedited treatment modality is required to improve the healing rate and to investigate if the high infection rate is related to treatment with BMP-7 activated muscle grafts.

Repair of large segmental bone defects: BMP-2 gene activated muscle grafts vs. autologous bone grafting

Background

Common cell based strategies for the treatment of osseous defects require the isolation and expansion of autologous cells. Since this makes such approaches time-consuming and expensive, we developed a novel expedited technology creating gene activated muscle grafts. We have previously shown that large segmental bone defects in rats can be regenerated by implantation of muscle tissue fragments activated by BMP-2 gene transfer.

Results

In the present study, we compared the bone healing capacities of such gene activated muscle grafts with bone isografts, mimicking autologous bone grafting, the clinical gold standard for treatment of bone defects in patients. Two of 14 male, syngeneic Fischer 344 rats used for this experiment served as donors for muscle and bone. Muscle tissue was harvested from both hind limbs and incubated with an adenoviral vector carrying the cDNA encoding BMP-2. Bone was harvested from the iliac crest and long bone epiphyses. Bone defects (5 mm) were created in the right femora of 12 rats and were filled with either BMP-2 activated muscle tissue or bone grafts. After eight weeks, femora were evaluated by radiographs, micro-computed tomography (μCT), and biomechanical testing. In the group receiving BMP-2 activated muscle grafts as well as in the bone-grafting group, 100% of the bone defects were healed, as documented by radiographs and μCT-imaging. Bone volume was similar in both groups and biomechanical stability of the two groups was statistically indistinguishable.

Conclusions

This study demonstrates that treatment of large bone defects by implantation of BMP-2 gene activated muscle tissue leads to similar bone volume and stability as bone isografts, mimicking autologous bone grafting.

Healing of large segmental bone defects induced by expedited bone morphogenetic protein-2 gene-activated, syngeneic muscle grafts

Numerous preclinical studies have shown that osseous defects can be repaired by implanting bone morphogenetic protein (BMP)-2-transduced muscle cells. However, the drawback of this treatment modality is that it requires the isolation and long-term (approximately 3 weeks) culture of transduced autologous cells, which makes this approach cumbersome, time-consuming, and expensive. Therefore, we transferred BMP-2 cDNA directly to muscle tissue fragments that were held in culture for only 24 hr before implantation. We evaluated the ability of such gene-activated muscle grafts to induce bone repair. Two of 35 male, syngeneic Fischer 344 rats used in this study served as donors for muscle tissue. The muscle fragments remained unmodified or were incubated with an adenoviral vector carrying the cDNA encoding either green fluorescent protein (GFP) or BMP-2. Critical-size defects were created in the right femora of 33 rats and remained untreated or were filled (press fitted) with either unmodified muscle tissue or GFP-transduced muscle tissue or with BMP-2-activated muscle tissue. After 6 weeks, femora were evaluated by radiography, microcomputed tomography (muCT), histology, and biomechanical testing. Six weeks after implantation of BMP-2-activated muscle grafts, 100% of the bone defects were bridged, as documented by radiographs and muCT imaging, and showed formation of a neocortex, as evaluated by histology. Bone volumes of the femora repaired by BMP-2-transduced muscle were significantly (p = 0.006) higher compared with those of intact femora and the biomechanical stability was statistically indistinguishable. In contrast, control defects receiving no treatment, unmodified muscle, or GFP-transduced muscle did not heal. BMP-2 gene-activated muscle grafts are osteoregenerative composites that provide an expedited means of treating and subsequently healing large segmental bone defects.

L'ambiance musculaire salvatrice en chirurgie réparatrice des cavités de pyothorax

SUBJECT

The chronic empyema is a dreadfull outcome of pulmonary resection. Its management is difficult: a thoracostomy or a thoracoplasty by resection of rib segments are rarely efficient. A large debridement associated with a muscular flap is helpfull in the treatment of these cavities. These flaps allow the filling of these pleural spaces and the treatment of the bronchopleural fistulae which are constant and responsible of the perenniality of such infection.

PATIENTS AND METHODS

From June 1997 to December 2006, 12 patients, aged from 25 to 45 years old, were treated for chronic empyema following total pulmonary resection by using muscular flaps. The causes were: post-tuberculosis pulmonary deterioration in 8 cases, bronchic cancer in 3 cases, post-traumatic tracheobronchic breaking in 1 case. An open window thoracostomy was performed for all the patients and with a follow-up of 2 years, there was no healing of this infection. In our procedure, the patients underwent in the same time a large thoracoplasty that involved 3 to 5 rib segments (10 cm in length) to reduce the pleural space and a myoplasty. The muscular flaps used were pedicled in 8 cases: a latissimus dorsi in 6 cases, a latissimus dorsi with an anterior serratus in 2 case, and were free in 4 cases: a latissimus dorsi in 3 cases, a latissimus dorsi with an anterior serratus in 1 case. These flaps were sufficient to fill the cavities and were applied and stitched around the fistulae.

RESULTS

There was no complication during or after the operations with a mean follow-up of 3 years. These chronic empyema were completely healed in all cases without recurrence of the suppuration or the bronchopleural fistulae.

CONCLUSION

The one-stage thoracomyoplasty including the resection of rib segments and local or regional muscular flaps is a very efficient treatment of the chronic pleural empyemas. It is very important, for an easy treatment of such cavities, to teach the thoracic surgeons the great interest of preserving the local muscular flap during the initial thoracotomy.

Use of the Extended-Pedicle Vastus Lateralis Free Flap for Lower Extremity Reconstruction

BACKGROUND

Soft-tissue coverage in the lower extremity usually requires a flap with a long pedicle, low donor-site morbidity, and versatility in terms of shape and volume. The extended-pedicle free vastus lateralis muscle flap has previously been described for head and neck cancer, and it fulfills these requirements.

METHODS

Twelve patients with lower extremity defects underwent reconstruction with an ipsilateral free vastus lateralis muscle flap. The flap included a segment of the distalmost part of the muscle, distal to the entry point of the motor nerve to the vastus lateralis, based on the descending branch of the lateral femoral circumflex vessels. Up to 20 cm of vascular pedicle with a large caliber was obtained. In three cases, a combined distal vastus lateralis and anterolateral thigh flap was used as a chimeric flap.

RESULTS

All flaps were successful. Infection developed in two cases and required flap reelevation and new wound debridement. There was no substantial subjective donor-site morbidity.

CONCLUSIONS

Elevation of the flap can be performed with the patient in the supine position and is extremely fast and straightforward, without the added difficulty of anatomical variation or extensive intramuscular vascular dissection. The pedicle is long and of large caliber. Although the series is short, the authors conclude that this is a useful free flap for lower extremity reconstruction.

Free deepithelialized anterolateral thigh myocutaneous flaps for chronic intractable empyema with bronchopleural fistula

BACKGROUND

Free deepithelialized anterolateral thigh (DALT) flaps have been used for treatment of chronic intractable empyema with bronchopleural fistula at Chang Gung Memorial Hospital since 1997.

METHODS

Twelve patients with chronic empyema were treated at Chang Gung Memorial Hospital from January 1997 to January 2001. Their age ranged from 31 to 70 years (mean age 48.6 years). Left-sided involvement was predominant (left to right ratio = 9:3). All patients had bronchopleural fistula, and all were cured. The average numbers of previous thoracotomy were 5.4. The ipsilateral DALT flaps were harvested with primary closure of donor site.

RESULTS

At a mean follow-up of 1 year, no recurrence was noted. All flaps survived well. The average hospital stay was 25.8 days. Complications after reconstruction included chrondritis, partial muscle necrosis, and wound dehiscence (1 patient each). There was no donor site morbidity.

CONCLUSIONS

Free DALT flaps can be selected according to different situations during surgery as long as they meet the following requirements: (1) tissue of sufficient volume and good blood supply, and (2) closure of the bronchial leak. Based on this retrospective study, use of free DALT flaps with technical refinement is a reliable method for treatment of chronic intractable empyema combined with bronchopleural fistula.