Biomedical subjects
Publications and source records attributed to C D Friedman.
This article reviews cartilage grafting in the head and neck, emphasizing its use in facial surgery. The harvesting and preparation of cartilage grafts are reviewed, and both autografts and homografts are discussed. The implementation of cartilage grafts in the nose, ear, eyelid, orbit, and larynx also is presented.
This study investigates the use of a new calcium phosphate cement, which sets to solid, microporous hydroxyapatite, for facial bone augmentation. In six dogs, the supraorbital ridges were augmented bilaterally with this hydroxyapatite cement. On one side, the hydroxyapatite cement was placed directly onto the bone within a subperiosteal pocket. On the opposite side, the cement was contained within a collagen membrane tubule and then inserted into a subperiosteal pocket. The use of collagen tubules facilitated easy, precise placement of the cement. All implants maintained their original augmented height throughout the duration of the study. They were well tolerated without extrusion or migration, and there was no significant sustained inflammatory response. Histologic studies, performed at 3, 6, and 9 months revealed that when the cement was placed directly onto bone, progressive replacement of the implant by bone (osseointegration of the hydroxyapatite with the underlying bone) without a loss of volume was observed. In contrast, when the cement-collagen tubule combination was inserted, primarily a fibrous union was noted. Despite such fibrous union, the hydroxyapatite-collagen implant solidly bonded to the underlying bone, and no implant resorption was observed. Hydroxyapatite cement can be used successfully for the experimental augmentation of the craniofacial skeleton and may be applicable for such uses in humans.
The use of gradual distraction to grow bone (distraction osteogenesis) has gained widespread orthopedic acceptance, but has only recently been applied to craniofacial skeletal defects. The use of bifocal distraction osteogenesis to fill experimental segmental mandibular defects with regenerate bone was recently reported. Though all canines in that study demonstrated normal oromandibular function, they were observed for only 4 weeks following defect closure. The study that is now reported describes the long-term (12-month) functional, morphologic, and biomechanical results when bifocal distraction osteogenesis was applied to the same model. In this long-term study, three canines had 2.5-cm unilateral segmental mandibular body defects filled with structurally stable bone using bifocal distraction osteogenesis. These dogs exhibited normal oromandibular function for 1 year following segment regrowth and external fixator removal. Macroscopic and histologic evaluation of the regrown segments revealed a re-formation of the cortical and medullary architecture. Stress testing demonstrated the average ultimate strength of the regrown segment at 53 MPa, which corresponded to 77% +/- 5.7% of normal mandibular bone. The data suggest that clinical trials applying this technique to segmental mandibular reconstruction are warranted.
Explore the source record for details and available documents.
The pectoralis myocutaneous flap has been widely used for reconstruction of oral cavity and pharyngeal defects. However, it has several disadvantages, such as chest distortion, hair growth at the reconstructed site, and excessive bulk, all of which can be avoided by the use of the pectoralis myofascial flap. Oral cavities and pharyngeal defects, ranging in size from 4 to 9 cm in largest' dimension, in 26 patients were reconstructed with the pectoralis myofascial flap. All but three defects were successfully reconstructed. The surface of the flap was covered by squamous epithelium in 1 month. The flap remained healthy during and after radiotherapy. The pectoralis myofascial flap is ideal for soft-tissue coverage of small- to medium-size oral cavity and pharyngeal defects. Its major advantages over the pectoralis myocutaneous flap are decreased bulk and improved cosmesis.
Explore the source record for details and available documents.
Defects comprising more than 50% of the trachea cannot be reliably reconstructed by any current technique or prosthesis. A composite tracheal replacement implant consisting of a Dacron-urethane mesh tube and revascularized jejunal autograft was applied to this problem. This composite implant was used to replace 7 to 10 cm of trachea in eight dogs. The implant was sewn to the outside (serosal surface) of the jejunum to provide permanent structural support to the autograft, and an intraluminal silicone tube was placed inside the jejunal segment and left for 4 weeks following reconstruction. Six of eight animals survived the predetermined time periods and were killed painlessly in groups of two animals at 1, 2, and 6 months after removal of the intraluminal silicone tube. Postoperative intubation, ventilation, or tracheostomy was not necessary. Excessive secretions were not seen in any of the animals, and a fair to good performance status was maintained until death in all but one animal. Histologic examination revealed slight thinning of the jejunal mucosa, with no change in the jejunal muscularis. These data suggest that with further refinement this composite implant may be a viable reconstructive option in humans.
Explore the source record for details and available documents.
Hydroxyapatite cement is a calcium phosphate-based material that when mixed with water forms a dense paste that sets within 15 minutes and isothermically converts in vivo to a microporous hydroxyapatite implant. This cement was used to reconstruct bilateral 2.5-cm-diameter full-thickness critical-sized parietal skull defects in six cats. One side was reconstructed with 100 percent hydroxyapatite cement, and the other with a mixture of 50 percent hydroxyapatite cement and 50 percent ground autogenous bone by weight. These animals were sacrificed at 6 and 12 months after implantation. Positive and negative controls also were prepared. The anatomic contour of the soft tissue overlying all hydroxyapatite cement implants was well maintained, there were no wound infections or structural failures, and the implants were well tolerated histologically. None of the negative (unreconstructed) control defects was completely filled with repair bone, and all positive (methyl methacrylate) controls demonstrated foreign-body giant-cell formation and fibrous encapsulation of the implants. Examination of decalcified and undecalcified sections revealed progressive but variable replacement of the cement by new bone and soft tissue without a change in the shape or volume of the hydroxyapatite cement-reconstructed areas. New bone comprised 77.3 and 64.7 percent of the tissue replacing the hydroxyapatite cement and hydroxyapatite cement-bone implants, respectively. Replacement of the hydroxyapatite cement implants by new bone is postulated to occur by a combination of osteoconduction and implant resorption. These results indicate that further experimental research leading to the possible application of hydroxyapatite cement for full-thickness calvarial defect reconstruction in humans is warranted.
Explore the source record for details and available documents.
Hydroxyapatite cement is a unique calcium phosphate preparation that can be shaped intraoperatively and sets in vivo to an implant composed of microporous hydroxyapatite. The histologic response to this cement was evaluated by implanting disks made of this material within the heads of nine cats. Three sets of 12 hydroxyapatite cement disks were produced containing 0%, 10%, and 20% macropores by volume, respectively. The disks were implanted subcutaneously, intramuscularly, above the periosteum of the skull, and directly onto the surface of the calvarium. Each macropore percentage was represented in each tissue plane, and animals were killed up to 9 months postoperatively. There were no toxic reactions, implants extruded, or wound infections. Histologic examination of the implant-soft-tissue interfaces revealed a transient inflammatory response without foreign body reaction. The disks were resorbed over time in direct proportion to their macropore content (surface areas) in all groups except for those disks placed directly onto the surface of the calvarium below the periosteum. In this group, numerous foci of bone formed at the skull-implant interface, with variable replacement of the deep surface of these implants by bone. Implant replacement by bone is postulated to occur through a combination of implant resorption coupled with osteoconduction. Based on these properties, hydroxyapatite cement may prove useful when applied to the reconstruction of non-stress-bearing skeletal tissue.
Frontal sinus obliteration and reconstruction can be performed with autogenous grafts or synthetic implants, each of which has significant limitations. Hydroxyapatite cement, which can be shaped intraoperatively and sets to a microporous hydroxyapatite implant, was applied to this problem. Nine cats had the anterior table of their frontal sinus unilaterally removed and the sinus cavity stripped of its mucosa. Hydroxyapatite cement was used to obliterate the cavity and reconstruct the overlying anterior table defect. The unoperated side served as the control, and the animals were sacrificed up to 18 months postoperatively. There were no adverse reactions, infections, mucoceles, or implant extrusions. The normal anatomic contour of the forehead region overlying the hydroxyapatite cement implants was maintained in all animals. Histologic examination of undecalcified whole sinus sections revealed progressive replacement of the implants with woven bone without a loss of volume. Replacement of the hydroxyapatite cement by woven bone is postulated to occur through a combination of implant resorption coupled with osteoconduction. The use of hydroxyapatite cement proved successful for the reconstruction and obliteration of cat frontal sinuses, and may be appropriate for the same application in humans.
One experimental surgical technique of bone replacement demonstrates the greatest potential for clinical applicability in the near future: the regrowth of bone by distraction (stretching). Distraction osteogenesis defines the technique of growing new bone by stretching existing bones. Although this technique does not represent the ultimate method of mandibular reconstruction, it shows sufficient promise that its eventual use for specific types of mandibular defects probably will occur in the near future.
We report the use of distraction osteogenesis for segmental mandibular regeneration. This technique has been used in thousands of patients in the Soviet Union to regenerate as much as 30 cm of tubular bone in the extremities. However, we are unaware of previous experimental or clinical reports of segmental mandibular regeneration by distraction osteogenesis. In a canine model, 2.5-cm segmental mandibular defects were filled with regenerate bone in 25 days at a rate of 1.0 mm/d using bifocal distraction osteogenesis. The diameters of the regenerate segments were comparable with preexisting mandible, and all animals resumed normal oromandibular function following regeneration. The regenerate bone was evaluated radiographically, angiographically, and histologically. In the control group without distraction osteogenesis, the segmental defects failed to fill with regenerate bone. The theoretical basis for distraction osteogenesis, a detailed description of the technique, and a review of previous studies on experimental mandibular lengthening are presented.
Extracranial meningiomas comprise approximately 2% of all meningiomas. Primary extracranial meningiomas are even less common. This report details our experience with these unusual tumors from 1972 to 1989. The diagnosis, surgical management, and significant histopathologic features are discussed. The correlation of primary extracranial meningiomas with neurofibromatosis type II and a treatment algorithm are presented.
Longitudinal voice quality changes following Isshiki thyroplasty type I were investigated in a group of 13 patients exhibiting unilateral vocal fold paralysis. Thyroplasty type I medializes the paralyzed fold by using a Silastic implant for external lateral compression of the abducted fold. No perioperative complications were experienced. We observed significantly higher voice fundamental frequency, significantly louder voice intensity, and significantly longer maximum phonation time, both immediately following phonosurgery and up to 3 months postoperatively. Surgical refinements of thyroplasty type I are described.
Horizontal osteotomy allows the surgeon to safely down-fracture the maxilla for wide exposure of the central skull base. This surgical approach is easily extended posteriorly in the midline to include the clivus and the arch of C1, providing 8 cm of horizontal anterior exposure and 5 cm of posterior. Wide operative exposure and a low rate of complications afford superior functional and cosmetic preservation in removing tumors of the central cranial base.
A discussion of the biology of bone healing serves as the basis for a review of the clinical management of maxillofacial skeletal injury in the geriatric patient. Age-related changes in the facial skeleton and fractures of the edentulous mandible are described in detail.