The effect of therapeutic irradiation on LactoSorb absorbable copolymer

Clinical experience of thoracoplasty with absorbable rib substitutes

PURPOSE

Malignant chest wall tumors are rare in pediatrics. They require multimodal oncological treatment and local surgical control. Resections are extensive; therefore, thoracoplasty should be planned to protect intrathoracic organs, prevent herniation, future deformities, preserve ventilatory dynamics, and enable radiotherapy.

METHODS

We present a case series of children with malignant chest wall tumors and our surgical experience with thoracoplasty using absorbable rib substitutes (BioBridge®), after local surgical control. BioBridge® is a copolymer made of a polylactide acid blend (70% L-lactic acid y 30% DL-lactide).

RESULTS

In 2 years, we had three patients with malignant chest wall tumors. Resection margins were negative, without recurrence at follow-up. We achieved good cosmetic and functional results, and no postoperative complications.

CONCLUSION

Alternative reconstruction techniques such as absorbable rib substitutes provide protection, guarantee a flexible chest wall, and do not interfere with adjuvant radiotherapy. Currently, there are no management protocols in thoracoplasty. This option represents an excellent alternative for patients with chest wall tumors. Knowledge of different approaches and reconstructive principles is essential to offer children the best onco-surgical option.

Chest wall reconstruction after tumor resection

Pediatric chest wall tumors are rare. Malignancies predominate of which sarcomas are the most common. Their resection and the subsequent reconstruction of the chest wall has been a surgical challenge since Dr. Frederick W. Parham published his first comprehensive account on the subject in 1898. Chest wall reconstruction is age, site and pathology dependent, must preserve long term function and cosmesis, must accommodate future growth and development, and must not be a hindrance to adjuvant radiotherapy. Bony reconstruction can be relatively simple or complex involving combinations of synthetic meshes, bioprosthetic materials, steel or titanium constructs, autografts, homografts and porcine or bovine xenografts. Soft tissue coverage can be achieved with direct closure, skin grafts, local advancement flaps, pedicled or free myocutaneous or osseomyocutaneous flaps or a combination of these. Complications to be avoided include scoliosis, pain and activity restriction, restrictive pulmonary deficits and interference with adjuvant radiotherapy which may result in tumor recurrence. Advances in cancer therapy have improved short- and long-term survival but significant functional and cosmetic challenges remain particularly for large chest wall defects in the very young. The future may lie with absorbable semi-rigid meshes, biointegratable acellular homografts and xenografts, demineralized bone matrices and bone marrow stromal cells, the patient's own lab-grown stem-cell based vascularized osseomyocutaneous chest wall grafts or the obsolescence of surgical resection altogether in the age of targeted anti-tumor and immune based therapy.

Thoracic wall reconstruction with bioabsorbable plates in pediatric malignant thoracic wall tumors

AIM

Childhood malignant chest wall tumors may require extensive surgical resection and reconstruction with musculoskeletal flaps or non-resorbable prosthetic materials. Implant-related complications and scoliosis often occur. This study analyzes the outcomes of chest wall reconstruction using resorbable plates as an alternative approach.

METHODS

Retrospective review (2007-2015) of patients who underwent resection of malignant primary chest wall tumors in 2 tertiary pediatric centers. Reconstruction was performed using copolymer (l-lactic and glycolic acid) plates, fixed to the ribs and surrounding structures with copolymer screws and/or polyglactin sutures.

RESULTS

Eight patients aged 10.6+2.6years were treated. There were no operative complications, and implant removal was not required in any case. Six patients received postoperative radiotherapy. Over follow-up (39.6months, range 9.4-78), chest wall shape was maintained in all, and there were no radiological artifacts. Three patients developed scoliosis (Cobb 17°-33°), but treatment was needed only in one, who had undergone hemivertebrectomy. There were no cases of local tumor relapse. One patient died because of metastatic spread.

CONCLUSIONS

Implantation of bioabsorbable l-lactic and glycolic acid copolymer plates with a relatively simple technique provided a rigid, stable reconstruction with only mild mid-/long-term complications. Resorbable plates may be a good alternative for pediatric chest wall reconstruction.

LEVEL OF EVIDENCE

IV.

Update on craniofacial surgery

Over the course of the past year, many interesting aspects of the multidisciplinary approach to the treatment of craniofacial disorders have been furthered. Several authors have shared their experiences, and new innovations have been described. Traditional ideas with regard to bone healing and growth have been expanded upon, and the role of alloplasts also is better understood now. Diagnosis and treatment planning have come a long way with the advent of new imaging techniques and applications. The ongoing discussion regarding absorbable fixation devices has continued, and the development of new technology has been presented. Some new techniques have also been brought to the forefront. Of note, distraction osteogenesis has been embraced as a viable alternative to traditional maxillomandibular surgery with bone grafting as well as other morbid procedures.

Mechanical characteristics of an absorbable copolymer internal fixation pin

Absorbable internal fixation is gaining acceptance among foot and ankle surgeons. While absorbable pins made of poly-L-lactic acid, polyglycolic acid, or poly-p-dioxanone are generally effective as applied in the foot, their strength loss profiles and degradation characteristics may not be optimally matched to the healing process. This study investigated a novel absorbable oriented copolymer pin, with unique absorption characteristics, made of 82% poly-L-lactic acid and 18% polyglycolic acid, to determine its suitability for use in fixation in the foot. The pins were incubated in a 37 degrees C buffer bath that simulated in vivo conditions and were mechanically tested in four-point bend and shear at time intervals up to 12 weeks. In vitro strength loss profiles demonstrated peak strength retention (flexural and shear) for about 8 weeks, with 50% of properties remaining by 12 weeks. The initial Young's modulus of the pins was approximately 7 GPa. The mathematical relationship between pin strength and pin diameter was discussed, providing the surgeon with helpful criteria for making an implant selection. The degradation time course of these pins appears to compliment the known healing dynamics of bone, making them a suitable choice for use in foot surgery.