Oral Cavity Reconstruction Outcomes Using a Porcine Urinary Bladder Matrix: A Retrospective Case Series

OBJECTIVE

The purpose of this study is to assess healing outcomes in full-thickness mucosal wounds following the use of a porcine urinary bladder matrix to augment mixed oral cavity repairs.

MATERIALS AND METHODS

A retrospective chart analysis was conducted over a 58-month timespan. Participants included individuals with osteoradionecrosis. Descriptive measures obtained in the postoperative setting were used to examine wound healing outcomes.

RESULTS

Thirty-nine encounters with 35 patients met inclusion criteria for assessment. The mean defect size repaired was 14 cm2. Successful healing occurred in 64% of cases. Scarring was observed in 10 cases, and 3 cases demonstrated transient functional deficits. Reapplication of the xenograft was required in 4 cases. Only 1 acute event of hemorrhage and 1 infection were observed in the postoperative period.

CONCLUSIONS

Use of porcine urinary bladder matrix grafts for oral cavity reconstruction was well tolerated in a diverse number of wound scenarios with a relatively low risk of postoperative complication. The use of porcine urinary bladder matrix was not observed to provide any noteworthy advantages for the healing of recalcitrant osteoradionecrosis wounds.

Osteoradionecrosis of the mandible: a review

BACKGROUND

Osteoradionecrosis is a serious complication of radiotherapy that often leads to severe facial deformity, pain, pathological fracture, sequestration of devitalized bone, and orocutaneous fistulas. Preventive measures for osteoradionecrosis are the best treatment plan to avoid osteoradionecrosis. Radical surgery is indicated when conservative methods fail or when severe bone and soft-tissue necrosis prevails.

CASE REPORT

The purpose of this paper is to explore the recent theories about the definition, classification, incidence, and pathophysiology of osteoradionecrosis (ORN) of the jaws. The predisposing and risk factors for the development of osteoradionecrosis based on the literature review along with case report are also discussed.

DISCUSSION

A better understanding on the risk factors responsible for causing ORN and the underlying pathophysiology may improve our ability to prevent this complication and help to improve the prognosis for those being treated for osteoradionecrosis.

[Pelvic bone radionecrosis as a late consequence of short-distance radiation therapy]

The paper deals with the estimation of the capabilities and role of different radiation techniques in the detection of late postradiation therapy local tissue responses that are evident as radionecrosis. To specify the nature of changes, it is necessary to take into account clinicoanamnestic data, results of laboratory and instrumental studies (standard X-ray study, multislice computed tomography, and magnetic resonance imaging) at any examination stage. A set of the studies can provide the means of significantly analyzing the bone structures and soft tissues and the degree of injury and identifying complications.

Osteoradionecrosis of the jaws--a current overview--part 1: Physiopathology and risk and predisposing factors

PURPOSE

The aim of this paper is to explore the current theories about definition, classification, incidence and physiopathology of osteoradionecrosis (ORN) of the jaws. Moreover, it is discussed the predisposing and risk factors for the development of osteoradionecrosis based on the literature review.

DISCUSSION

Osteoradionecrosis is one of the most serious oral complications of head and neck cancer treatment. Osteoradionecrosis is a severe delayed radiation-induced injury, characterised by bone tissue necrosis and failure to heal. Osteoradionecrosis either stabilises or gradually worsens and is notoriously difficult to manage. The most widely accepted theory to explain its cause until recently was the theory of hypoxia, hypovascularity and hypocellularity. A new theory for the pathogenesis of osteoradionecrosis was proposed. The clinical presentations of osteoradionecrosis are pain, drainage and fistulation of the mucosa or skin that is related to exposed bone in an area that has been irradiated. The tumour size and location, radiation dose, local trauma, dental extractions, infection, immune defects and malnutrition can predispose its development.

CONCLUSIONS

A better understanding of risk factors for the development ORN and of the underlying pathophysiology may improve our ability to prevent this complication and help to improve the prognosis for those being treated for osteoradionecrosis.

A preliminary investigation into the effects of X-ray radiation on superficial cranial vascularization

Radiation therapy (RT) is an established treatment modality for malignant neoplasms. RT induces tissue damage that may lead to osteoradionecrosis in more severe cases. Suitable animal models to study RT-induced changes in membranous craniofacial bone are currently not available. The aim of this study was therefore to quantify RT-induced changes in cranial microcirculation using a newly developed calvaria chamber model and to relate these changes to RT-induced histological damage. New Zealand white rabbits received a total radiation dose of 18.75 Gy through the calvaria chamber, and the number of vessels, the vessel length density (VLD), and angiogenic sprouting were quantified on a weekly basis during a 12-week period. At the end of 12 weeks, the RT-treated (n = 5) or control (n = 5) calvarias were biopsied for histopathological analysis. RT resulted in a steep reduction in the number of vessels and the VLD during the first 3 weeks, particularly in larger-diameter vessels, followed by a flat stabilization/remodeling phase in the subsequent 9 weeks that never restored to baseline values. Histomorphometric analysis revealed a high degree of osteocytic depletion, prominent hypocellularity in the lacunae and intraosseous vasculature, enlarged and nonconcentric Haversian systems, and a severely disorganized bone matrix in the RT-treated calvarias. Despite the prevalence of some angiogenic potential, the RT-induced effects in the early phase persisted in the intermediate to late phase, which may have contributed to the poor recovery of the RT-treated bone.

HDR brachytherapy irradiation of the jaw - as a new experimental model of radiogenic bone damage

INTRODUCTION

Hitherto, no suitable experimental model exists to test new treatments for radiogenic bone damage, such as new step from knowledge about bone growth factors or angiogenesis factors. The goal of this investigation was to establish such a standardised experimental model.

MATERIAL AND METHODS

Twenty-four rats were used in this study. In 12 rats a plastic tube was implanted along the right half of the mandible and treated with a single dose of 20 Gy at a high-dose-rate (HDR) using an afterloading machine, the remainder served as control (n=12). One hundred days after irradiation both sides of the mandible were examined using paraffin embedding and non-decalcified histology.

RESULTS

All HDR irradiated rats developed localised alopecia within 2 weeks of radiotherapy. In the irradiated group, a clear growth reduction of the ipsilateral incisor was observed. Paraffin histology revealed minimal damage of the bone structure with slightly increased signs of regeneration. The bone apposition rate was significantly reduced on the irradiated right side, compared with the left side (p=0.028). The average diameter of the mandibular condyles on the irradiated right sides was significantly reduced when compared with the left sides (p=0.023).

CONCLUSIONS

It is possible to induce radiogenic damage of the mandible by using HDR brachytherapy with a single dose of 20 Gy comparable to 45 x 2 Gy of conventional irradiation. This new model is easy and predictable and appears to be suitable for the testing of new treatment modalities. It is advantageous for the testing of bone growth and angiogenesis factors that the contralateral side exhibits completely normal bone apposition characteristics enabling a split-mouth design for future experiments.

Use of osseointegrated implants in the restoration of head and neck defects

Osseointegrated implants can be applied to facilitate retention, stability, and support for facial and intraoral prostheses used to restore head and neck defects. At the University of California, Los Angeles, Maxillofacial Prosthetics Clinic, retrospective studies have indicated that in nonirradiated maxillectomy patients, implant survival rates are 82.6 percent. In mandibles reconstructed with fibula free flaps, survival rates are 94.6 percent. Similarly, high implant survival rates have been observed for most sites used to support facial prostheses. Cumulative six-year survival rates for auricular sites exceed 95 percent and for floor of nose sites, success rates exceed 87 percent. However, survival rates are low (53 percent) for implants placed in the frontal bone for retention of orbital prostheses and even lower for irradiated bone sites ranging from 63 percent in the maxilla to 27 percent in the orbit.

A murine model for bone loss from therapeutic and space-relevant sources of radiation

Cancer patients receiving radiation therapy are exposed to photon (gamma/X-ray), electron, and less commonly proton radiation. Similarly, astronauts on exploratory missions will be exposed to extended periods of lower-dose radiation from multiple sources and of multiple types, including heavy ions. Therapeutic doses of radiation have been shown to have deleterious consequences on bone health, occasionally causing osteoradionecrosis and spontaneous fractures. However, no animal model exists to study the cause of radiation-induced osteoporosis. Additionally, the effect of lower doses of ionizing radiation, including heavy ions, on general bone quality has not been investigated. This study presents data developing a murine model for radiation-induced bone loss. Female C57BL/6 mice were exposed to gamma, proton, carbon, or iron radiation at 2-Gray doses, representing both a clinical treatment fraction and spaceflight exposure for an exploratory mission. Mice were euthanized 110 days after irradiation. The proximal tibiae and femur diaphyses were analyzed using microcomputed tomography. Results demonstrate profound changes in trabecular architecture. Significant losses in trabecular bone volume fraction were observed for all radiation species: gamma, (-29%), proton (-35%), carbon (-39%), and iron (-34%). Trabecular connectivity density, thickness, spacing, and number were also affected. These data have clear implications for clinical radiotherapy in that bone loss in an animal model has been demonstrated at low doses. Additionally, these data suggest that space radiation has the potential to exacerbate the bone loss caused by microgravity, although lower doses and dose rates need to be studied.

An unusual lesion on the chest wall

Osteoradionecrosis is an exceptional complication after the treatment of breast carcinoma. We report here a 63-year-old woman who presented with osteoradionecrosis of the sternum 17 years after initial treatment for breast cancer. Difficulty in diagnosing the lesion and its management is discussed.

Expression of bone morphogenic protein 2/4, transforming growth factor-β1, and bone matrix protein expression in healing area between vascular tibia grafts and irradiated bone—experimental model of osteonecrosis

PURPOSE

For the surgical treatment of osteoradionecrosis after multimodal therapy of head-and-neck cancers, free vascular bone grafts are used to reconstruct osseous structures in the previously irradiated graft bed. Reduced, or even absent osseous healing in the transition area between the vascular graft and the irradiated graft bed represents a clinical problem. Inflammatory changes and fibrosis lead to delayed healing, triggered by bone morphogentic protein 2/4 (BMP2/4) and transforming growth factor (TGF)-beta(1). Given the well-known fibrosis-inducing activity of TGF-beta(1), an osteoinductive effect has been reported for BMP2/4. However, the influence of irradiation (RT) on this cytokine expression remains elusive. Therefore, the aim of the present in vivo study was to analyze the expression of BMP2/4, TGF-beta(1), collagen I, and osteocalcin in the transition area between the bone graft and the graft bed after RT.

METHODS AND MATERIALS

Twenty Wistar rats (male, weight 300-500 g) were used in this study. A free vascular tibia graft was removed in all rats and maintained pedicled in the groin region. Ten rats underwent RT with 5 x 10 Gy to the right tibia, the remainder served as controls. After 4 weeks, the previously removed tibia grafts were regrafted into the irradiated (Group 1) and nonirradiated (Group 2) graft beds. The interval between RT and grafting was 4 weeks. After a 4-week osseous healing period, the bone grafts were removed, and the transition area between the nonirradiated graft and the irradiated osseous graft bed was examined histomorphometrically (National Institutes of Health imaging program) and immunohistochemically (avidin-biotin-peroxidase complex) for the expression of BMP2/4, TGF-beta(1), collagen I, and osteocalcin.

RESULTS

Absent or incomplete osseous healing of the graft was found in 9 of 10 rats after RT with 50 Gy and in 1 of 10 of the rats with nonirradiated osseous grafts. Histomorphometrically, the proportion of osseous healing in the transition area was 17% in Group 1 and 48% in Group 2 (p = 0.001). Compared with the nonirradiated rats, reduced enchondral and perichondral ossification was found in the healing area after RT, with a reduction of BMP2/4 and osteocalcin expression. TGF-beta(1) and collagen I expression in the transition area to the irradiated osseous graft bed was significantly increased compared with that in the nonirradiated osseous graft bed.

CONCLUSION

After RT, osseous healing of vascular bone grafts is significantly reduced and may be a result of radiation-induced inhibition of BMP2/4 and osteocalcin expression. In addition, induction of TGF-beta(1) and collagen I expression occurs. Because the effects of the TGF-beta superfamily are manifold and partially unknown, additional research directions could be in the exogenous application of BMP2/4 and inhibition of TGF-beta(1) by antibody treatment to search for appropriate therapeutic approaches for improving osseous healing in the irradiated graft bed.

Effect of age and repeated hyperbaric oxygen treatments on vagal tone

OBJECTIVES

To evaluate the influence of repeated hyperbaric oxygen (HBO2) exposures and age on vagal response to hyperbaric oxygenation, and to evaluate the timing of changes in vagal activity during the treatments.

STUDY DESIGN

Open, controlled, non-randomized study.

METHODS

Heart rate variability of 23 patients with chronic osteomyelitis or radionecrosis of the jaw or reconstructive surgery of the facial region was studied during repeated treatments. During each treatment, the patients were exposed to HBO2 at 2.5 ATA and heart rate variability was measured using power spectral analysis before compression, three times at 2.5 ATA and during and after decompression. The patients were grouped according to age (Cut-off point 50 years). Statistical analysis was carried out using analysis of variance for repeated measurements.

RESULTS

Repeated exposures did not change vagal response to hyperbaric oxygenation. Vagal activity measured by HF power increased significantly in both age groups during the HBO2 exposures but there were no significant difference between the groups in the response. However, the level of HF power was significantly higher in the subjects under 50 years old. Significant differences between consecutive measurements were related to pressure changes.

CONCLUSIONS

Repeated therapeutic HBO2exposures are not causing permanent changes in vagal control of the heart. Vagal responsiveness to hyperbaric hyperoxia is preserved in advanced age.

[Mature bone radionecrosis: from recent physiopathological knowledge to an innovative therapeutic action]

Osteoradionecrosis is a severe radiotherapy (RT) injury by healing failure, late effect and spontaneously irreversible by tissue death. Histologically, it consists in a pagetoid mosaic that combines a defective osteogenesis with an osteoclastic osteolysis and more marginally an osteolytic osteolysis, turned to account to fibroblastic and collagenic fibrosis. Several pathogenic hypotheses favor sometimes a vascular hypoxic hypotheses, sometimes a fibro-atrophic hypothesis. Various events start up or favour ORN as traumatisms (dental extraction, surgery,...) or bacterian infection on fistula. In clinic, adult mature bone concerned is the mandible after head and neck RT by septic ORN, and the hip after pelvic RT by aseptic ORN. For each, epidemiology, clinic and therapeutic aspects are developed. Usual therapeutic attitudes consisted in restriction of defavorable associated events (dental extraction, infection, RT dose, chemotherapy,...) and devitalized tissue removal. Physiopathological therapeutic innovatives aspects are proposed to struggle against radiation-induced fibrosis associated and to limit bone destruction.

Hyperbaric oxygen treatment and pulmonary function

Hyperbaric oxygen (HBO2) treatment exposes the lungs to the potentially toxic effect of free oxygen radicals and may lead to impairment of pulmonary function. HBO2 significantly improves wound healing in patients with osteoradionecrosis of the mandible following radiation therapy for intraoral cancer. In 18 consecutive patients with osteoradionecrosis of the mandible, pulmonary function was assessed during 6 wk of HBO2 treatment, applied daily in a monoplace chamber for 90 min and at a partial oxygen pressure of 2.4 atm abs. Pretreatment forced vital capacity (FVC) was 104 +/- 14% (mean +/- SD) of a reference population, the 1 s forced expiratory volume (FEV1) 95 +/- 20%, total lung capacity (TLC) 100 +/- 13%, and the carbon monoxide diffusing capacity (DL(CO)) 81 +/- 17% (P < 0.05, compared to reference population). These parameters remained unchanged throughout the treatment period (after 6 wk and expressed relative to the percentage of the expected value at baseline): deltaFVC: +4 +/- 8%; deltaFEV1: -2 +/- 4%; deltaTLC: +2 +/- 5%; deltaDL(CO): 0 +/- 9%; deltaRV 0 +/- 11%. It is concluded that intermittent HBO2 treatment in a monoplace chamber has no persistent effect on pulmonary function and can be offered even to patients with a reduced diffusing capacity.

[Late effects of ionizing radiations on head and neck region tissues]

Numerous structures are included in the irradiated volume of patients presenting with head and neck cancer: skin, mucosa, bone, teeth, cartilage, muscles, salivary glands, etc. Curative intent treatment of such tumours requires aggressive approach which can lead to severe sequellae. These sequellae are in most cases dose-dependent and volume-dependent. However, an appropriate technique might decrease the severity of such sequellae. Details of these late changes are presented, including their pathophysiology, clinical syndromes, potential treatment, and prevention.

The use of implants in the reconstruction of oral cancer patients

The spectrum of osseointegrated implant applications in cancer patients is quite varied today. In the future, it will be even wider and more varied, limited only by the ingenuity of practitioners, skills of reconstructive surgeons, biology of the reconstruction, and cost restraint efforts. Today's practitioners are challenged to preserve and enhance the benefits of osseointegrated implants in some of the patients who need them most, the cancer patient. It is done by improving one's own skills by research and by education.

Irradiated bone and its management

There are two undeniable attributes of radiotherapy: its value in controlling head and neck malignancies and the progressive damage it inflicts on all treated tissues. It is fortunate that over the past decade, we have developed techniques and treatments that counteract, at least in part, the negative effects of radiotherapy on bone. Some of these measures are purely preventive and must be employed before or during radiation therapy to be successful. They include limiting the total radiation dose to less than 7000 Rads, appropriately shielding structures that do not require radiation, sparing one or more major salivary glands to minimize xerostomia, limiting fraction dosages to less than 200 Rads, obtaining pre-radiation dental evaluations, and performing dental extractions before radiotherapy begins. Additionally, treatments have been devised to prevent ORN following radiotherapy. They consist of patient participation in aggressive dental maintenance programs, oral fluoride treatments, and the use of preextraction hyperbaric oxygen when unhealthy teeth need to be removed. Should radiation-induced complications develop in spite of these efforts, treatments have been developed that effectively deal with ORN, namely, hyperbaric oxygen (the Marx protocol) and prolonged courses of intravenous antibiotics. Finally, when ORN results in mandibular loss and deformity, these defects can be effectively reconstructed with either corticocancellous particulate bone grafts or microvascular osseous tissue transfers, depending on the clinical situation. Much can be done to prevent and treat radiation-induced complications involving bone, and it remains the responsibility of the head and neck surgeon to make sure that these measures are utilized. When all priorities in treating ORN are considered, differentiating a radiation-induced wound healing problem from a delayed tumor recurrence remains paramount. This differentiation should always be the first step in the treatment of any radiation-induced wound.

Radiation injury to the temporal bone

Osteoradionecrosis of the temporal bone is an unusual sequela of radiation therapy to the head and neck. Symptoms occur many years after the radiation is administered, and progression of the disease is insidious. Hearing loss (sensorineural, conductive, or mixed), otalgia, otorrhea, and even gross tissue extrusion herald this condition. Later, intracranial complications such as meningitis, temporal lobe or cerebellar abscess, and cranial neuropathies may occur. Reported here are five cases of this rare malady representing varying degrees of the disease process. They include a case of radiation-induced necrosis of the tympanic ring with persistent squamous debris in the external auditory canal and middle ear. Another case demonstrates the progression of radiation otitis media to mastoiditis with bony sequestration. Further progression of the disease process is seen in a third case that evolved into multiple cranial neuropathies from skull base destruction. Treatment includes systemic antibiotics, local wound care, and debridement in cases of localized tissue involvement. More extensive debridement with removal of sequestrations, abscess drainage, reconstruction with vascularized tissue from regional flaps, and mastoid obliteration may be warranted for severe cases. Hyperbaric oxygen therapy has provided limited benefit.

Osteoradionecrosis: a new concept of its pathophysiology

The classic sequence in the pathogenesis of osteoradionecrosis of the jaws has been accepted as radiation, trauma, and infection. This paper challenges this sequence and offers a new one more accurately describing the biochemical and cellular pathology. The clinical data are based on 26 consecutive cases of osteoradionecrosis from which 12 en bloc resection specimens were cultured and stained for microorganisms. Review of the histories and treatments, as well as the microbial assays, indicates that microorganisms play only a contaminant role in osteoradionecrosis and that trauma is only one mechanism of tissue breakdown leading to the condition. The sequence suggested by this study is as follows: (1) radiation, (2) hypoxic-hypocellular-hypovascular tissue, (3) tissue breakdown, and (4) chronic non-healing wound.

Osteoradionecrosis of the temporal bone

Six cases of osteoradionecrosis of the temporal bone are described. Persistent symptoms of otitis externa refractory to local treatment measures should alert the physician to the possibility of underlying osteoradionecrosis. Treatment of superficial parotidectomy and partial temporal bone resection with preservation of the facial nerve is indicated if local aggressive conservative measures fail to control the disease. Benign mixed tumors of the parotid gland should be treated surgically with avoidance of radiotherapy.