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Biomedical subjects

D K Ousterhout

Publications and source records attributed to D K Ousterhout.

At least 19 recordsLinked to original sources
PubMed1997

A method for repairing zygomatic arch fractures using a hydroxyapatite cement paste (BoneSource).

A new method has been developed for the closed reduction of minimally displaced, noncomminuted zygomatic arch fractures that is minimally invasive and precludes the use of nonresorbable materials such as plates and wires in the repair. Twenty rats received simple, minimally displaced right-sided zygomatic arch fractures under general anesthesia. In 10 animals these fractures were treated with closed reduction through a temporal approach (Gillies method) to reapproximate the fractured segments. In the second group of 10, immediately after the closed fracture reduction, 1 ml of hydroxyapatite cement paste (BoneSource, Leibinger Corp., Dallas, TX) was injected through a 14-gauge needle into and around the fracture site. This paste, which is remodeled into bone over time, hardens into a plaster-like substance within 20 minutes of mixing. The majority of the paste was placed on the medial aspect of the fracture to act as a buttress between the fractured zygoma and the temporalis muscle lying on the greater wing of the sphenoid. This served to support the fracture by "casting" the bone and preventing it from collapsing medially. Nine of the 10 fractures treated with the hydroxyapatite paste healed completely without evidence of zygomatic displacement or malunion. One fracture had mild displacement of the fractured segment but good bone healing between the fractured sides. No adverse effects were noted in the temporalis muscle of these animals, and mastication was normal. Five of the 10 treated with closed reduction alone also had a good result. Of the remaining 5 fractures 2 had a mild to moderate bony deformity as a result of improper alignment during fracture healing. The other 3 did not heal and, therefore, formed a fibrous nonunion at the fracture site. We concluded that closed reduction of simple zygomatic fractures can be performed if the fracture site is held in place with a stabilizing material such as a hydroxyapatite cement paste.

Animals↗
PubMed1997

Hydroxyapatite paste (BoneSource) used as an onlay implant for supraorbital and malar augmentation.

This study was designed to evaluate hydroxyapatite paste (BoneSource; Leibinger Corp., Dallas, TX) as an alloplastic implant for supraorbital and malar augmentation. Ten male Sprague-Dawley rats had cylindrical onlay implants made of the hydroxyapatite cement placed above their left orbits on the supraorbital rim. Size-matched Medpor implants were placed similarly on the right side. To test the utility of this new material in the midface, hydroxyapatite paste and Medpor implants were also placed in the right malar regions of a different set of rats. The implants were left in situ for 6 months and examined for evidence of bone ingrowth, infection, migration, resorption, and detrimental effects on the surrounding tissue. All hydroxyapatite cement implants provided excellent soft tissue projection and demonstrated steadfast adherence to the adjacent bone. The surface of the hydroxyapatite implant in contact with the native bone demonstrated evidence of native bony ingrowth into approximately 12% of the implant. There was no evidence of implant migration or gross infection. There was no bony resorption below the hydroxyapatite paste, but four of the Medpor implants showed evidence of this in the underlying bone. Only one negative aspect to the use of hydroxyapatite cement paste as an onlay implant was identified. Two of the supraorbital and one of the malar hydroxyapatite implants had approximately 20 to 25% volume loss during the experimental period (P = 0.05). Overall, the vast majority of the implants retained their original form. We concluded that hydroxyapatite paste may possibly be used to effectively augment bone in the supraorbital and malar regions. Its biocompatibility, excellent bony adherence, and tendency to be replaced by natural bone may make it suitable for the aesthetic patient. The possible resorptive aspects of the material need to be evaluated further.

Animals↗
PubMed1996

Prevention of thermal tissue injury induced by the application of polymethylmethacrylate to the calvarium.

The exothermic reaction produced during the polymerization of polymethylmethacrylate yields temperatures in excess of 180 degrees F (81.4 degrees C). At these elevated temperatures, significant bone and dural necrosis occurs. In an attempt to prevent thermal injury during craniofacial surgery, surgeons irrigate the polymerizing implant with cold saline, assuming that this will decrease both the absolute temperature elevation and the duration of the exothermic reaction, making the use of methylmethacrylate safe. Unfortunately, no experimental evidence exists to support this claim. To test the safety of methylmethacrylate during craniofacial surgery, we constructed an in vitro model that allowed us to measure directly the heat transferred from the methylmethacrylate to the underlying dura or bone during polymerization. In this model, the methylmethacrylate implants were 6 cm in diameter, but they varied in thickness. We hypothesized that methylmethacrylate could be safely applied up to a certain thickness, after which the temperature rise on the undersurface of the implant would no longer be controlled by any amount of cold saline irrigation, and thermal necrosis would occur. We found that without irrigation all implants produced temperatures in excess of 180 degrees F (81.4 degrees C) internally. This peak temperature lasted for approximately 45 seconds and then declined to a baseline temperature of 98 degrees F (36.3 degrees C) over 5 to 6 minutes. Upon irrigation of the implants with cold saline (4 degrees C), the level and duration of temperature elevation conducted to the underlying surface varied significantly on the basis of implant thickness. Implants smaller than 5 mm thick produced temperatures on the bone surface of 108 degrees F (41.8 degrees C) for 11 seconds. This temperature control was partially lost at 7 mm when the underlying surface reached a temperature of 134 degrees F (56.1 degrees C) for 15 seconds. Methylmethacrylate implants with a thickness greater than 7 mm produced temperatures of 145 degrees F (62.2 degrees C) for 22 seconds, indicating that the cold was insufficient to protect against thermal injury. Therefore, we conclude that polymethylmethacrylate can be applied safely to the skull if the implant is 6 mm thick or smaller. With polymethylmethacrylate thicker than this, the heat produced during polymerization cannot be controlled, and thermal necrosis to the underlying tissues is inevitable.

Bone Substitutes↗
PubMed1996

Sliding genioplasty, avoiding mental nerve injuries.

Mental nerve injuries have been inculcated in sliding genioplasty. An anatomical study was completed (and published) that demonstrated a surgical approach that would, it was hoped, prevent such nerve injuries. A prospective clinical study to test this hypothesis has now been completed. On the basis of the anatomical finding mentioned previously, fifty consecutive sliding genioplasties were compared with the immediate 50 consecutive sliding genioplasties preceding the anatomical finding. Sensation testing was based on multiple finger touches on both sides of the lower lip and chin in both groups. The anatomical finding was that in none of the mandibles studied did the inferior alveolar nerve canal dip more than 5.5 mm below the inferior border of the mental nerve canal. All the osteotomies in the prospective study were completed with at least 6 mm between the most proximal osteotomy and the inferior border of the mental nerve canal. In the retrospective cases, the distance between the canal and the osteotomy was generally not recorded. Surgery was completed on a broad spectrum of aesthetic and congenital-developmental deformities. In the 50 prospective cases, there were no permanent mental nerve injuries. There were three permanent injuries (one bilateral complete numbness, one unilateral complete numbness, and one unilateral partial numbness). Although keeping 6 mm or more between the inferior border of the mental nerve canal and the proximal osteotomy during sliding genioplasty does not absolutely rule out or prevent an injury to the inferior alveolar nerve within the bony canal, it seems that by not keeping the 6 mm the chances of a nerve injury would be greatly increased. It seems advisable to always keep 6 mm as a minimal distance because avoiding a nerve injury should be an obligatory goal of this surgery. If a greater distance can be kept without decreasing the aesthetic result, it should be considered.

Chin↗
PubMed1996

Airway changes after Le Fort III osteotomy in craniosynostosis syndromes.

The purpose of this study was to investigate changes in the nasopharyngeal airway and surrounding structures after Le Fort III advancement in Apert's and Crouzon's syndromes. Sixteen status post Le Fort III osteotomy Apert's and Crouzon's patients with pre- and postoperative lateral cephalograms were evaluated. The cephalograms were traced, and linear and angular measurements were obtained. Pre- and postoperative data were compared using a Student's paired t-test. The correlation between changes in the nasopharyngeal airway and its surrounding skeletal structures was evaluated. Finally, the study subjects were divided into two groups--Apert's and Crouzon's--and preoperative measurements from each group were compared with normal data by a Student's paired t-test. Significant improvement in the nasopharyngeal airway followed Le Fort III advancement, with changes in both hard and soft tissues. There was no change in the pharyngeal airway, even though a decrease might be predicted because of the clockwise rotation of the mandible. The morphology of the impairment in the nasopharyngeal airway differed between Apert's and Crouzon's syndrome individuals. Our results suggest that, for the purpose of airway improvement, the midface should be mainly advanced in the Crouzon's syndrome individual, whereas the downward component of the movement should be predominant in the Apert's syndrome individual.

Acrocephalosyndactylia↗
PubMed1996

Correction of enophthalmos in progressive hemifacial atrophy: a case report.

This case report describes a technique used for correction of enophthalmos secondary to progressive hemifacial atrophy (Parry-Romberg syndrome). The only previous described technique utilized an orbital floor implant, but this method was apparently only partially successful in correcting the conditions, i.e., it did not correct both the enophthalmos and the pseudoptosis that occurs secondary to intraorbital fatty atrophy. In the present technique, the periorbita was cut at two equators, the globe and anterior periorbita advanced forward, and the resulting empty spaces filled with thin slices of radiated cartilage. Both the enophthalmos and the pseudoptosis were corrected in a single operation. There were no long-term complications and the correction has been maintained 3 years postoperatively.

Adult↗
PubMed1996

Plastic surgery's plastics.

Alloplastic materials have become an essential part of reconstructing the craniofacial skeleton. This article reviews several of the more commonly used implant materials and summarizes their mechanical properties and use in reconstructive surgery.

Biocompatible Materials↗
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↗
PubMed1992

The course of the inferior alveolar neurovascular canal in relation to sliding genioplasty.

The anterior course of the inferior alveolar neurovascular canal was determined in 52 hemimandibles using high-resolution radiographs. Significant variability was found in its course. It was noted that if the osteotomies for sliding genioplasty were performed at least 6 mm below the inferior border of the mental foramen, injury to the mental nerve would be reduced.

Chin↗
PubMed1992

Recipient vessels for microvascular transplants in patients with hemifacial microsomia.

Hemifacial microsomia is a developmental abnormality involving structures derived from the first and second branchial arches. Microvascular transplants are increasingly being used to improve facial contour in patients with this condition. We have reviewed 9 patients with this abnormality to determine which recipient vessels have been used. In 6 patients, the facial vessels were located and used for flap revascularization. In 3 patients, the facial vessels could not be identified intraoperatively, and the occipital artery and a branch of the external jugular vein were used as recipient vessels. In this series of hemifacial microsomia patients, therefore, the facial vessels could not be located in 3 patients. We recommend that surgeons performing microsurgical transplants in cases of hemifacial microsomia be prepared to explore the external carotid and external jugular systems for recipient vessels.

Face↗
PubMed1991

Mandibular angle augmentation and reduction.

The mandibular angle is receiving more attention as now every area of the craniofacial skeleton is a candidate for aesthetic modification. Both reduction and augmentation of this posterior area of the mandible are addressed. Surgical techniques, results, and complications are described after the cosmetic problems are demonstrated. Representative cases are presented.

Bone Transplantation↗
PubMed1990

Aesthetic improvement of the forehead utilizing methylmethacrylate onlay implants.

Forehead augmentation occasionally is necessary for obtaining a desirable upper facial contour. The final contour must be sexually appropriate and must project beyond the cornea of the eyes an amount that makes the contour aesthetically pleasing. Methylmethacrylate onlay implants, preformed or sculpted at the time of surgery, lend themselves to obtaining a desirable contour which can be modified easily at surgery, which is completed in a one-stage procedure, has few complications, and yields an aesthetically pleasing result. The methods for fabricating and implanting the onlay prosthesis in a single step and the results of such procedures, which have been performed over a 12-year period without complications, are presented.

Forehead↗
PubMed1990

Histologic evaluation of the coronal sutures in trigonocephaly.

Thirteen cases of trigonocephaly, seven isolated and six syndromic cases, were evaluated by preoperative neurologic and genetic evaluation and by radiographic evaluation (CT scans). All 13 were treated in an identical surgical manner. Specimens from the coronal sutures were obtained during surgery for histologic evaluation. All of the isolated cases, except one, showed normal coronal sutures and had a good-to-excellent result from surgery. All of the syndromic or secondary cases showed an abnormality of the coronal sutures. Four of the six cases had bad results; two required subsequent surgical procedures. It is our opinion that if a coronal suture abnormality is noted on preoperative CT scans or if preoperative evaluation demonstrates an associated syndrome or CNS malformation, the results from surgery must be guarded.

Cranial Sutures↗
PubMed1990

Long-term follow-up on a case of untreated trigonocephaly.

Trigonocephaly is typically treated during the second 3 months of life by metopic suture synostectomy, orbital rim advancement, and cranioplasty. The results are generally very pleasing in nonsyndromic patients. We have not, however, seen adults with residual deformity who preceded the present basic approach to treatment first described by Hoffman and Mohr (1976). Dominguez et al (1981) described 15 individuals who improved without treatment. The question that arises is whether we are treating this congenital problem unnecessarily, particularly in nonsyndromic patients. We present a 38-year-old untreated woman who still has residual signs of the deformity seen in early childhood photographs.

Adult↗
PubMed1990

Combined suction-assisted lipectomy, surgical lipectomy, and surgical abdominoplasty.

Although combined suction-assisted lipectomy (SAL) and surgical abdominoplasties have been described, the surgical excisions have in general been small and limited to the lower portion of the lower abdomen (i.e., just above the pubis). For the obese patient this is an insufficient lipectomy. SAL alone is unsatisfactory because the marked skin excess will not shrink sufficiently to allow a desired final result. Surgical abdominoplasty alone is also insufficient in the obese patient because the thickness of the abdominal panniculus is not reduced and, additionally, secondary to tissue tension with wound closure, some necrosis of skin above the pubis is not unusual. In this article results are described from a small consecutive series of obese patients treated with a combined extensive SAL, surgical lipectomy, and surgical abdominoplasty. The sequence of fat removal is different than that which has been previously described. In all of the patients the results were pleasing, and there were only two relatively minor complications.

Abdomen↗