Experimental study of tracheal allotransplantation with cryopreserved grafts

OBJECTIVE: Tracheal reconstruction is necessary in patients with extensive tracheal stenosis caused by neoplasm, trauma, and congenital disease. We investigated the possibility of tracheal allotransplantation with cryopreserved grafts in a canine model. METHODS: A seven-ring section of thoracic trachea was removed in 19 adult mongrel dogs. In group A (n = 4), a five-ring tracheal autograft was implanted. In group B (n = 6), a five-ring allograft was implanted without immunosuppression. In group C (n = 9), a five-ring cryopreserved tracheal allograft was implanted without immunosuppression. Omentopexy wrapping around the grafts and both anastomotic sites was used in all animals. RESULTS: All grafts survived without any evidence of atrophy or stenosis in group A. All animals in group B died of severe airway obstruction within 1 month, and postmortem examination of these grafts showed epithelial defect and necrotic tracheal cartilage in the scar tissue. In group C, no animals died of asphyxia caused by severe stenosis of the grafts. The graft epithelium was no longer present 20 days after transplantation, and the graft was covered with regenerated epithelium within about 60 days after the operation. CONCLUSION: These findings show that cryopreserved tracheal allografts can be transplanted by means of omentopexy without immunosuppression and that cryopreservation may reduce tracheal allogenicity.     

A comparison of vascularized and nonvascularized bone grafts for reconstruction of mandibular continuity defects

PURPOSE: This study compared vascularized and nonvascularized bone grafts for the reconstruction of segmental defects of the mandible. PATIENTS AND METHODS: The results in 39 patients having vascularized bone grafts (38 fibulas and one iliac crest) and 29 patients having nonvascularized bone grafts (26 iliac crest [22 corticocancellous block grafts, four cancellous bone grafts in a tray] and three rib grafts) for segmental mandibular reconstruction were evaluated in terms of overall success rate, total number of surgeries performed, total blood loss, total number of hospital days, and total number of hours in the operating room. RESULTS: Of 39 vascularized bone grafts, two failed (95% success rate), whereas of 29 nonvascularized bone grafts, seven failed (76% success rate). Failure for the nonvascularized bone grafts was closely correlated to the length of the defect. Nonvascularized bone graft patients underwent an average of one more surgical procedure for total reconstruction than vascularized bone graft patients, including osseointegrated implants. However, vascularized bone graft patients spent a mean of over 14 additional days in the hospital for all of their reconstructive procedures and an additional 3 hours in the operating room as compared with nonvascularized bone graft patients. Blood loss was similar in both groups (1,100 mL). Only 20% to 24% of patients in each treatment group have completed reconstruction to include osseointegrated implants. CONCLUSIONS: The success rate for vascularized bone grafting is high and is the treatment of choice when primary reconstruction is required, when the patient has been previously irradiated, or when simultaneous replacement of soft tissue is required. Vascularized bone grafts are also the treatment of choice for mandibular replacements over 9 cm in length. Nonvascularized bone grafts create a better contour and bone volume for facial esthetics and subsequent implant insertion, and may be the treatment of choice for secondary reconstruction of defects less than 9 cm in length.     

Histological study of the tracheal adventitia, perichondrium and annular ligament

The trachea begins at the lower border of the cricoid cartilage and passes down to bifurcate into the left and right mainstem bronchi. The presence of tracheal invasion is crucial factor influencing the prognosis for patients with cancers of the thyroid gland, hypopharynx, esophagus, etc. In order to understand the manner of invasion of the above tumors, precise knowledge of the normal tracheal structure is indispensable. This study was undertaken to clarify the normal microscopic structure of the trachea. Five normal tracheal specimens obtained at surgery were examined histologically and immunohistochemically. The loose connective tissue around the trachea, known as adventitia, was divided into a loose outer and a dense inner layer by hematoxylin and eosin (HE) staining. This two-layer pattern was clearly seen near the annular ligament but was obscured away from it. The connective tissue of the inner layer ran obliquely to joint the connective tissue of the annular ligament and ended in the submucosal layer. This arrangement of connective fibers seems to play a role in allowing the trachea to stretch and bend. Tracheal cartilage is covered with a dense fibrous membrane known as the perichoundrium. Between the superficial fibrous membrane and mature cartilage cells lies zone of immature cartilage made up of oval or spindle cells, and the inclusion of this zone in the perichondrium has long been a subject of controversy. In our study, the zone was homogeneously stained red by the elastica van Gieson's stain and was clearly distinguished from other structures. Immunohistochemical staining revealed a wide distribution of type I and type III collagen on the fibrous membrane and the zone of immature cartilage cells, while mature cartilage cells did not show such collagen. Based on these findings, we conclude that the zone of immature cartilage cells belongs to the periochondrium, which thus contains two layers, an outer fibrous layer and an inner transitional layer of immature cartilage cells. Our conclusions are as follows: 1. Tracheal adventitia is divided into two layers, an outer loose and an inner dense fibrous layer. 2. Tracheal perichondrium also consists of two layers, an outer fibrous layer and an inner transitional layer. 3. The fibrous bundle originating from the adventitia joins the connective tissue of the annular ligament, probably in order to allow the trachea to stretch and bend.     

Use of ultrasonography in the diagnosis of tracheal collapse

Ultrasonographic imaging of the cervical trachea was performed with the neck in both a neutral and a hyperextended position in 10 dogs with tracheal collapse. Tracheoscopy was used to confirm a diagnosis of tracheal collapse. The ultrasound investigation was repeated in 10 dogs of similar size but without tracheal abnormality. The ultrasonographic findings of the affected dogs were compared with those of the normal group and showed an alteration in the shape of the tracheal lumen in the ventrodorsal projection. This study highlights the possibility of identifying changes in the shape of the tracheal lumen during ultrasound investigations as an aid to the diagnosis of tracheal collapse.     

Long-term follow-up of immunosuppressive treatment for obstructive airways disease after allogeneic bone marrow transplantation

BACKGROUND: Locally advanced thyroid cancer invading the tracheal cartilage represents a difficult treatment dilemma during thyroidectomy. METHODS: A retrospective chart review was performed to determine the results of laryngotracheal resection or tracheal cartilage shave with adjuvant radiotherapy in patients with locally advanced thyroid cancer invading the upper airway. RESULTS: Of 597 patients undergoing thyroidectomy for thyroid cancer, 40 were found to have laryngotracheal invasion. Thirty-five patients with superficial invasion underwent cartilage shave procedures with adjuvant radiotherapy; five with full-thickness invasion underwent radical resection, including tracheal sleeve resection (n = 3) or total laryngectomy (n = 2). Histologic subtypes included papillary (n = 32), follicular (n = 2), Hurthle cell (n = 1), medullary (n = 3), and anaplastic (n = 2). Of the cartilage shave group, 25 are currently alive with no evidence of disease at a mean follow-up of 81 months (range 1-290). Six developed isolated local/regional recurrence and were managed with total laryngectomy (n = 1), tracheal resection (n = 1), cervical lymphadenectomy (n = 1), or repeat radiotherapy (n = 3). All six patients remain free of disease at a mean follow-up of 5 years. Of those who underwent initial laryngotracheal resection, four remain free of disease at a mean follow-up of 5 years. The rates of 10-year disease-free survival and overall survival for all patients were 47.9% (95% confidence interval [CI] 24.8, 71.0) and 83.9% (95% CI 70.3, 97.5), respectively. CONCLUSIONS: These data suggest that adequate management of thyroid cancer with laryngotracheal invasion can be achieved with a more conservative surgical approach and adjuvant radiotherapy, reserving more radical resections for extensive primary lesions or locally recurrent disease.     

The inferior thyroid veins--the ultimate guardians of the trachea

The inferior thyroid veins and their multiple tributaries are the ultimate guardians of the cervical trachea. Deeply embedded in the pretracheal fat pad, this plexus of veins is consistently encountered during low tracheostomy that accompanies conservation laryngral procedures as well as in tracheal reconstruction. In a high tracheotomy, the handling of the thyroid isthmus is simplified by an appreciation of these veins. Even cricothyrotomy is potentially complicated by hemorrhage sebsequent to a tear in a tributary of the inferior thyroid venous system. A cadaver study, employing 10 embalmed head and neck specimens, was performed to elucidate the tributary patterns of these veins. In every dissection there was at least one and as many as five veins overlying the trachea just below the thyroid isthmus. In 7 of 10 dissections a confluence of right and left inferior thyroid veins formed a large thyroid ima vein draining into the left innominate vein, and in 1 of 10 cases the thyroid ima vein drained into the right innominate. This confluence was present at a level which would be encountered in low tracheostomy or tracheal repair procedures. Six of 10 dissections presented large tributaries of the inferior thyroid veins overlying the cricothyroid membrane. An awareness of such anatomical considerations should result in safer surgical procedure performed in a dry operative field.     

Experimental study of tracheal patch reconstruction with a covered expandable metallic stent

BACKGROUND: We evaluated the efficacy of tracheal patch reconstruction with a covered expandable metallic stent (EMS) with omentoplasty. METHODS: After resecting the right half of the circumferential wall of two tracheal rings in adult beagle dogs, we inserted a covered EMS to reconstruct the defect interiorly. Then, through laparotomy, we made an omental pedicle flap and wrapped it around the EMS-interposed area. For comparison with the group without omentoplasty, we periodically examined the healing process macroscopically and histologically. RESULTS: Bronchofiberscopic observations revealed that incorporation of the covered EMS progressed with the passage of time and tracheal luminal patency was maintained well in both groups. However, polyplike granulation developed gradually at both ends of the EMS. Histologically, epithelium was regenerated in the patched area 4 weeks postoperatively and the area was covered with pseudostratified ciliated epithelium at 12 weeks postoperatively. Quantitative analysis of the macroscopic and histologic findings showed that the inflammatory polyps were reduced and epithelialization was promoted in the group with omentoplasty. CONCLUSIONS: Tracheal patch reconstruction with a covered EMS, when combined with omentoplasty, promoted early epithelial regeneration and suppressed the development of inflammatory polyps.     

Poxvirus dilemmas--monkeypox, smallpox, and biologic terrorism

Three children with tracheomalacia had tracheal reinforcement with free three-quarter circumference ring grafts of autologous cartilage taken from the costal margin. A low cervical manubrium-splitting approach gave excellent access to the anterior mediastinum and the intrathoracic trachea in two children. The first child, a neonate with oesophageal atresia (OA) and tracheo-oesophageal fistula (TOF), had 11 grafts to support the whole of the trachea from the cricoid to the carina and never required a tracheostomy. For the first 5 years she had frequent pneumonic episodes and on one occasion bilateral pneumothoraces. These episodes and radiographic lung hyperinflation, attributed to distal bronchomalacia, have reduced spontaneously in frequency and severity. At 9 years of age she has a well-supported trachea with palpable cartilage rings in the cervical segment. The trachea has grown to approximately 75% of expected normal size for her age. Another child with tracheomalacia related to innominate-artery compression and who presented with 'dying episodes' was completely relieved and resumed a normal life without a tracheostomy following insertion of four grafts to the intrathoracic trachea. He remains well and symptom-free 8 months postoperatively. A third child had cartilage-graft reinforcement of the lower cervical trachea, including the tracheostomy site, to achieve tracheostomy closure at 16 months of age. Five years later he continues to have a well-supported trachea showing acceptable growth. However, he has ongoing evidence of tracheo-bronchomalacia presenting as expiratory wheezing, lung hyperinflation, and pneumonic episodes that are diminishing spontaneously with growth. Our experience, limited to three children, recommends primary tracheal reinforcement with autologous free costal-cartilage grafts for tracheomalacia in the neonate and young infant. This procedure and the anterior mediastinal approach are well-tolerated, providing instant tracheal support, removing the need for a tracheostomy, and allowing the child's rapid return to the family. Long-term follow-up, presently 9 and 5 years in two children originally presenting with OA and TOF, indicates adequate tracheal growth and an aesthetically acceptable appearance. It is relevant to prognosis that relief of the life-threatening tracheal component exposed the full extent of the bronchial cartilaginous weakness, which has significantly detracted from the quality of life for these two children with OA and TOF-related tracheomalacia.     

Photoreceptor allografts in a feline model of retinal degeneration

BACKGROUND: Photoreceptor transplants provide a potential means to restore function in a degenerate retina and/or rescue degenerating host photoreceptors by trophic influences. We have examined photoreceptor allografts in the Abyssinian cat model of hereditary photoreceptor degeneration to determine the viability and influence of such transplants on the host retina. METHODS: Small pieces of 3- to 5-day-old normal kitten retina containing undifferentiated photoreceptors were injected into the subretinal space of adult Abyssinian cats at an early stage of retinal degeneration using standard vitreo-retinal surgical techniques. The retinas were examined by ophthalmoscopy and fundus photography, then by light and electron microscopy at different times after surgery. RESULTS: Such allografts survive for at least 6 months after surgery. The photoreceptors develop outer segments, invariably in rosettes. The transplants gradually integrate with the host retina but detach the host photoreceptor layer from the retinal pigment epithelium (RPE), which tends to reduce the number of host photoreceptors over the transplant. There is no slowing of the photoreceptor degeneration in neighboring non-detached retina. Inflammation or rejection was not detected. CONCLUSION: Undifferentiated, neonatal photoreceptor allografts survive and develop outer segments in the subretinal space of the Abyssinian mutant feline retina. The allografts gradually integrate with the host neural retina without inducing rejection. In the vicinity of the transplant there is increased loss of host photoreceptors, considered to be due to their detachment from the RPE layer. There is no evidence of any rescue of host photoreceptors elsewhere in this mutant retina.     

Pathologic staging of papillary carcinoma of the thyroid with airway invasion based on the anatomic manner of extension to the trachea: a clinicopathologic study based on 22 patients who underwent thyroidectomy and airway resection

We received the clinical and pathologic features of 22 cases of papillary carcinoma of the thyroid that invaded the trachea and were treated by thyroidectomy and airway resection with or without reconstructive surgery over an interval of 16 years. We studied the fine relationships between lamina propria and lymphatics in the region between the isthmus of the thyroid and the trachea. The manner of invasion of papillary carcinoma of the thyroid was by blunt dissection along blood vessels and collagen fibers oriented perpendicularly to the tracheal lumen between cartilaginous rings. Although lymph node metastases were found in 14 patients (64%), we observed lymphangitic tumor in the tracheal mucosa in only three patients (14%). We devised a staging system for papillary carcinoma of the thyroid based on the extent of invasion of the trachea. Of the 11 patients with stage I, II, or III disease, none of six (0%) followed for 5 years died of thyroid cancer in the 5-year observation period; one patient in this group died later of thyroid cancer. Of the 11 patients with stage IV disease, five of seven (71%) followed for 5 years died of thyroid cancer in the 5-year observation period; one additional patient in this group died later of thyroid cancer.     

Rosaceous lymphedema: a rare variant of a common disorder

Surgical reconstruction of the trachea is a relatively complex procedure. We had 20 cases of tracheal stenosis. We have a modest experience of 16 tracheal reconstructions for acquired tracheal stenosis. Two patients underwent laser treatment while another two died before any intervention. The majority of these cases were a result of prolonged ventilation (14 cases), following organophosphorous poisoning (11 cases), Guillain-Barré syndrome, bullet injury, fat embolism and surprisingly only one tumor, a case of mucoepidermoid carcinoma, who had a very unusual presentation. There were 12 males and 4 females in this series, age ranging from 12-35 years. The duration of ventilation ranged from 1-21 days and the interval from decannulation to development of stridor was between 5-34 days. Six of them were approached by the cervical route, 5 by thoracotomy and cervical approach, 2 via median sternotomy and 3 by thoracotomy alone. Five of them required an additional laryngeal drop and 1 required pericardiotomy and release of pulmonary veins to gain additional length. The excised segments of trachea measured 3 to 5 cms in length. All were end to end anastomosis with interrupted Vicryl sutures. We have had no experience with stents or prosthetic tubes. Three patients developed anastomotic leaks which were controlled conservatively. Almost all of them required postoperative tracheo-bronchial suctioning with fibreoptic bronchoscope. We had one death in this series due to sepsis.     

The use of autogenous fat, fascia, and nonvascularized muscle grafts in the head and neck

We have reviewed the transplantation of autogenous fat, fascia, and nonvascularized muscle. Although none of these tissues satisfies all of the requirements for an ideal transplantation material, understanding the indications and each material's limitations will broaden the surgeon's armamentarium when soft-tissue grafting is desired. Although the use of autogenous fat grafts in head and neck surgery has been associated with some unpredictability, fat remains an excellent choice for obliteration of frontal sinuses, for myringoplasty, and for limited soft-tissue augmentation. In most applications, significant resorption of the transplanted fat can be expected, and it should be compensated for accordingly by initial overcorrection. Future research endeavors, including development of preadipocyte transplants and hormonal manipulation of fat grafts, will perhaps improve results of transplantation. The grafting of fascia has been shown to be a very reliable technique, especially when tensile strength is required of the transplant material. In grafts, fascia is much more predictable than fat, in that the majority of the fascia survives as living tissue that retains its original characteristics. A relative lack of three-dimensional bulk, however, limits the use of fascia in soft-tissue augmentation. The transplantation of nonvascularized muscle, because of its enormous metabolic requirements, almost always results in death of the muscle cells and subsequent partial replacement by fibrous tissue. Free muscle grafts therefore have very limited application, except in circumstances in which fibrous tissue obliteration of small defects (such as the nasofrontal duct or eustachian tube) is the desired result. In clinical situations in which maintenance of the substance or bulk of the transplanted material is of paramount importance, consideration should be given instead to the transfer of vascularized tissue. For this purpose, numerous simple and composite flaps of fascia, fat, muscle, and other tissues are now available. Vascularized tissue transfers are certainly not the solution to every reconstructive problem, however. When properly selected and applied, the transplantation of fat, fascia, and occasionally muscle remains an important option for soft-tissue replacement in head and neck surgery.     

A case of idiopathic iliopsoas hematoma associated with liver cirrhosis

We report a rare case of intratracheal thyroid ectopia in the setting of papillary thyroid carcinoma, resulting in the preoperative clinical impression of an aggressive, high-stage tumor. A 24-year-old opera singer presented with complaints of a gagging or choking sensation. The results of computed tomography revealed a mass in the left thyroid lobe with multiple small calcifications consistent with papillary thyroid carcinoma as well as a soft tissue mass in the adjacent left tracheal lumen thought to be direct invasion by the thyroid tumor. A total thyroidectomy was performed including excision of half of the first and second tracheal cartilages and the lower portion of the hemicricoid cartilage. The final histological findings revealed that the intratracheal component was composed of benign thyroid tissue and strands of benign thyrocytes coursed through the first tracheal membrane. Intratracheal thyroid ectopia is a rare symptomatic occurrence with a striking female predisposition. We have identified 23 cases of intratracheal thyroid ectopia from the literature. They occur most often at the level of the cricoid, usually posteriorly with a slight predisposition for the left side. Continuity between the intratracheal component and the thyroid lobe may be seen. Clinicians and pathologists must be aware of this entity to avoid mistaking it for evidence of thyroid invasion by a malignant neoplasm.     

Improved airway healing using basic fibroblast growth factor in a canine tracheal autotransplantation model

OBJECTIVE: We studied 22 dogs to examine the effect of basic fibroblast growth factor (bFGF) alone, in comparison with omental or muscular wrapping on airway healing in a tracheal autotransplantation model. SUMMARY BACKGROUND DATA: Basic fibroblast growth factor is one of the most potent promoters of angiogenesis and has an ability to enhance blood supply to the ischemic airway. Topical administration of a fibrin glue enriched with 5 microg/cm2 bFGF, determined as a proportion of surface area of the tracheal grafts, improved revascularization of orthotopic canine tracheal autografts in a previous study. METHODS: All animals received orthotopic tracheal transplantation using 6-ring autografts that occupied a distal part of the thoracic trachea. Twenty-two animals were classified randomly into the following four groups: no treatment (Group G1, n = 4), muscular wrapping (Group G2, n = 4), omental wrapping (Group G3, n = 4), and topical administration of fibrin glue enriched with 5 microg/cm2 bFGF (Group G4, n = 10). Autografts were harvested 60 days after transplantation and assessed by the percent patency and histology. RESULTS: Devascularized tracheal autografts could not maintain their structural integrity without other treatments (Group G1). In contrast, more than half of all autografts receiving treatments remained viable, as demonstrated by gross and histologic findings (Groups G2, G3, and G4). Treatments with bFGF and omentum showed significantly better graft viability than no treatment. However, there was no statistical difference in the viability of tracheal autografts among the three treatment groups. In terms of the time performance ratio, bFGF was the best treatment for the devascularized autografts. CONCLUSIONS: Topical administration of bFGF was superior to the omental or muscular wrapping in terms of the time performance ratio. Clinical trials will be necessary to determine whether these findings are applicable to humans.     

Resection of the trachea infiltrated by thyroid carcinoma

Twenty-four thyroid carcinoma patients with infiltration of the trachea were treated surgically. The histological diagnosis in these cases included papillary adenocarcinoma in 22 different patients, medullary carcinoma in one patient, and undifferentiated carcinoma in one patient. In 19 of the patients hemoptysis was noted, and dyspnea was present in ten patients. In 14 of the 24 patients the carcinoma was diagnosed by radiographs of the neck, while in seven patients it was demonstrated bronchoscopically. In three patients tracheal infiltration by thyroid carcinoma was diagnosed by biopsy of the tracheal wall at operation. When the tracheal wall was infiltrated by thyroid carcinoma, treatment consisted of circumferential resection of the involved segment of the trachea followed by an end-to-end anastomosis. Of the 24 patients, 17 survived and six died. In the 17 patients who survived, 13 were disease free. Of this number, six survived more than five years after the initial tracheal resection.     

The vascularization characteristics of free transplants of the growth zones of the long tubular bones (experimental studies)

The authors have studied the process of revascularization of free transplants of growth zones of the bones transplanted heterotopically from greater trochanter of the femur onto the chest. The X-ray and histological data have shown the ingrowth of the vessels into autotransplants from the side of soft tissues of the recipient bed responsible for the growth of the epiphyseal cartilage.     

Long-term follow-up of the vascularized iliac bone graft

We retrospectively studied four patients who were treated with vascularized iliac bone graft for reconstruction of the tibia. The average length of the graft was 9.8 cm. The follow-up period was 11-18 years (average, 14.8 years). Although two of them were osteomyelitis, no recurrence occurred. We also studied four patients who were treated with nonvascularized iliac bone graft for anterior spinal interbody fusion (average, 10.8 years). Cosmetic problem slightly exists because the vascularized iliac bone still showed the original shape, which was prominent from the tibial contour. The vascularized iliac bone marrow showed iso intensity in both T1 and T2 image of the MRI. However, nonvascularized iliac bone graft on the spine showed high intensity in both T1 and T2 imaging. Since the vascularized iliac bone graft does not present fatty degeneration, it shows strong resistance against infection.     

Tracheomalacia with esophageal atresia and tracheoesophageal fistula in fetal rats

BACKGROUND: Many patients who have esophageal atresia and tracheoesophageal fistula (EA-TEF) have associated tracheomalacia, which is thought to be one of the reasons for respiratory complications after surgical correction of the abnormality. METHODS: In this study, tracheas from Adriamycin-induced EA-TEF fetal rats were examined histologically and relevant cross-sectional parameters of the tracheas were measured. RESULTS: The tracheal lumen in tracheomalacia was small and irregular, losing its normal "D" shape. In most rats, the cartilaginous ring was broken into two to four segments, making the trachea lose its rigid support. The submucosa was thickened with prominent bulging of its membranous part into the tracheal lumen. The ratio of the inner luminal cross-sectional area to the outer tracheal cross-sectional area in EA-TEF rats was 15.7%, compared with a control ratio of 47.2%. In EA-TEF rats, the length of the cartilaginous ring was significantly shortened (P < .001), but not the length of membranous trachea, thus resulting in a cartilaginous/membranous (C/M) ratio of 1.55:1, markedly lower than that of normal rats (4.34:1, P < .001). The reduction of anterior-posterior diameter of the tracheal lumen was more marked than that of the transverse diameter. CONCLUSIONS: These observations suggest that the trachea in EA-TEF rats has a smaller lumen and is more flaccid than normal, making it prone to airway obstruction. The fact that tracheomalacia developed only in fetuses who had EA-TEF indicates that the factors that result in EA-TEF also cause tracheomalacia.     

Assessment of donor cell and matrix survival in fresh articular cartilage allografts in a goat model

The long-term survival of allografts of articular cartilage has been proposed to be dependent on the survival of the cells that maintain the unique structural and material properties of the allograft. In this study, we assessed cell survival in 24 fresh articular cartilage allografts of the medial plateau in a Spanish-goat model. A DNA-probe technique was used to distinguish clearly between DNA from donor (allograft) and host cells. The intraarticular survival of viable allograft chondrocytes in the transplanted articular cartilage started to diminish as early as 3 weeks after transplantation; however, there was considerable variation in the amount of donor cell DNA detected in the allografts at 6 and 12 months following transplantation. This contrasts with our experience with fresh allografts of ligament, tendon, and meniscus, in which no donor DNA was detected 4 weeks after transplantation. DNA from host cells was present in all articular cartilage allografts, as evidenced by detectable unique host DNA patterns. Histological and histochemical assays showed that none of the transplants demonstrated normal structure and composition at 1 year after transplantation. The grafts in which large quantities of donor DNA were present appeared grossly superior to those with no or reduced remaining demonstrable donor DNA.     

Endosseous implant and autogenous bone graft reconstruction of mandibular discontinuity: a 12-year longitudinal study of 31 patients

Surgical, medical, and prosthodontic records of 61 consecutively treated patients with mandibular discontinuity were reviewed retrospectively. All 61 patients had undergone discontinuity reconstruction with autogenous bone grafts; 31 of 61 had also received endosseous dental implants and a dental osseoprosthesis. Of these 31 implant-reconstructed patients, 23 had free autogenous nonvascularized and 8 had vascularized bone grafts. The surgical-prosthetic protocol consisted primarily of secondary, free autogenous nonvascularized bone graft reconstruction and secondary root-form endosseous implant and fixed prosthesis dental reconstruction. Vascularized bone (8 patients) or soft tissue (4 patients) grafts were utilized selectively for severely compromised patients after extensive oncologic resection, avulsive trauma, or after previous radiation treatment. Endosseous implant survival (95.5% in 31 patients), autogenous bone graft success (98.4% in 61 patients), and dental osseoprosthesis success (100% in 31 patients) were favorable. A high incidence (9.1%) of nonfunctioning (sleeping) implants was recorded for this patient population. The need to remove the titanium mesh tray for various reasons (17.6%) and the need to reconstruct soft tissue in the irradiated patient (12%) were noteworthy.