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Biomedical subjects

C D Friedman

Publications and source records attributed to C D Friedman.

At least 19 recordsLinked to original sources
PubMed1994

Polymeric implants in craniomaxillofacial reconstruction.

With advances in polymer chemistry, polymeric implants are becoming an increasingly attractive alternative to autogenous bone. Although polymeric implants were traditionally used to bridge bony defects and modify the overlying soft tissue envelope, new resorbable polymers may allow bony replacement and may be used as alternatives to metals in rigid fixation. This article contains an overview of polymeric implants from acrylics to modern resorbable polymers.

Humans↗
PubMed1994

Synthetic bone graft substitutes.

Some of the most significant advances in biomaterials over the last 20 years have been in the field of bone graft substitutes. Additionally, bone growth proteins were one of the first tissue-specific morphogenic factors to be characterized and produced by recombinant genetic technology. Consequently, the development of a new generation of totally synthetic, biologically active bone graft substitutes is just now beginning to move from the laboratory to clinical testing. It is entirely possible that within the next 10 to 15 years, the majority of "bone grafting" in craniofacial reconstructive surgery and in orthopedic surgery may be done with biologically active synthetic bone graft substitutes rather than natural bone sources. In fact, the harvesting of autogenous grafts may eventually prove to be the exception rather than the standard of care. Regardless of whether the potential of biologically active bone graft substitutes is ever fully realized, we now have a large number of synthetic alternatives to autogenous bone grafts for craniofacial skeletal augmentation and reconstruction. The reality of these synthetic bone graft substitutes is that no single material is "the best" for all applications. Instead, the specific biomaterial must be tailored to the individual site of application to achieve optimal results. The synthetic bone graft substitutes reviewed in this article represent only the "core" of synthetic biomaterials from which synthetic bone graft substitutes can be selected. Other articles in this monograph highlight the roles that various natural and biologically active bone graft substitutes play in craniofacial skeletal augmentation and reconstruction.

Bone Substitutes↗
PubMed1994

General concepts in craniofacial skeletal augmentation and replacement.

Craniofacial skeletal reconstruction has reached new levels of sophistication. The ability to precisely plan and execute these instructions affords better and more predictable outcomes of surgical therapy. This article will focus on the general concepts and principles for advanced craniofacial skeletal augmentation and replacement.

Bone Remodeling↗
PubMed1994

Nonvascularized autogenous bone grafts for craniofacial skeletal augmentation and replacement.

Autogenous nonvascularized bone grafts play an important role in the reconstruction of complex craniomaxillofacial defects. Experimental animal data have demonstrated that grafts from membranous bone donor sites tend to undergo less resorption than grafts from endochondral donor sites, probably because of the different bony architecture of each of these types of grafts. Of all the potential donor sites, the harvest of bone graft from the calvarium is associated with the least overall morbidity. Surgeons should be aware of the biologic basis for the successful application of free autogenous bone grafts.

Alveolar Ridge Augmentation↗
PubMed1994

Metal plate and screw technology.

Fundamental to the choice and proper application of plating systems in osteosynthesis of the craniomaxillofacial skeleton is an understanding of the basic design and biomechanical characteristics that define them. Improper selection of systems and technical execution of rigid internal fixation is not uncommon and may result in hardware failure, dysfunction, and dysmorphology. The surgeon who is able to command the nuances of system design and discipline in application will achieve superior functional and aesthetic results that are predictable and reproducible.

Bone Screws↗
PubMed1992

The pectoralis major myofascial flap for intraoral and pharyngeal reconstruction.

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.

Female↗
PubMed1992

Experimental tracheal replacement using a revascularized jejunal autograft with an implantable Dacron mesh tube.

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.

Animals↗
PubMed1992

Experimental hydroxyapatite cement cranioplasty.

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.

Animals↗
PubMed1991

Hydroxyapatite cement. I. Basic chemistry and histologic properties.

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.

Animals↗
PubMed1991

Hydroxyapatite cement. II. Obliteration and reconstruction of the cat frontal sinus.

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.

Animals↗
PubMed1991

Distraction osteogenesis. Applications for mandibular regrowth.

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.

Animals↗
PubMed1990

Segmental mandibular regeneration by distraction osteogenesis. An experimental study.

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.

Animals↗
PubMed1990

Primary extracranial meningiomas of the head and neck.

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.

Adolescent↗
PubMed1990

Longitudinal voice quality changes following Isshiki thyroplasty type I: the Yale experience.

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.

Adult↗
PubMed1990

Le Fort I osteotomy approach to the skull base.

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.

Adolescent↗