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Biomedical subjects

J C Posnick

Publications and source records attributed to J C Posnick.

At least 55 records · Page 3Linked to original sources
PubMed1994

An assessment of postnatal growth after in utero long bone osteotomy with fixation.

Researchers have recently suggested that rigid fixation of the immature bony skeleton may restrict growth and development. This study assesses the effect on postnatal growth of an in utero tibial osteotomy fixed with a miniplate in fetal sheep. A midshaft osteotomy was performed on fetal sheep tibia (n = 5) at 95 days' gestation (term 145 days). One tibia was reduced and fixed with a titanium miniplate and screws, while the contralateral hindlimb served as a control. The newborns were vaginally delivered and sacrificed at 2 months of age. The hindlimbs, control and fractured, were harvested, stripped of soft tissue, and the tibia, femur, and distal metatarsal were each measured and weighed. Each tibia also underwent radiographic analysis and histologic examination (after decalcification) using hematoxylin and eosin, Sirius red, and Alcian blue stains. No prenatal, postnatal, or perioperative medical complications occurred. Apart from a slight angulation in one operated tibia, no gross morphologic differences, either visible or palpable, were found between the operated and control limbs. This was confirmed radiographically where no remnant of the osteotomy site was visible. Measurements of the operated and control tibias, femurs, and metatarsal bones were not statistically different. Histologic analysis showed a total incorporation of bone at the osteotomy site with appositional growth present. All bone was lamellar with longitudinal orientation. In the area of the screw sites, the surrounding bone shaft was the same width as its neighboring bone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Facial sensibility in adolescents with and without clefts 1 year after undergoing Le Fort I osteotomy.

Static two-point discrimination, pressure, and vibratory threshold values were measured at standard coordinates in the area corresponding to the infraorbital nerve distribution in 59 adolescents 1 year after undergoing LeFort I osteotomy. The patients were divided into three groups: those born with unilateral cleft lip and palate (n = 30; mean age, 18 years; SD = 2); those with bilateral cleft lip and palate (n = 12; mean age, 19 years; SD = 3); and those without a cleft (n = 17; mean age, 19 years; SD = 3). One year after the osteotomy, none of the patients complained of altered sensibility in the maxillary vestibular mucosa, gingiva, or upper lip and cheek regions. No significant differences were found between the mean postoperative sensibility values of patients with and without clefts, indicating that the presence of clefting did not affect sensory recovery. Mean postoperative static two-point discrimination values were higher than preoperative values in all areas tested and in all patient groups. These results suggest that the sensory recovery, although incomplete, was strong enough to mask any subjective feelings of changes in sensory function.

Adolescent↗
PubMed1994

Skeletal stability and relapse patterns after Le Fort I maxillary osteotomy fixed with miniplates: the unilateral cleft lip and palate deformity.

The outcomes of a consecutive series of 35 adults and adolescents judged to be skeletally mature (mean 18 years) who had unilateral cleft lip and palate and had undergone Le Fort I advancement fixed with miniplates were investigated. All patients had received grafts of autogenous iliac bone and were stabilized intraoperatively with four miniplates. The amount and timing of horizontal and vertical relapse, correlation between advancement and relapse, effect of a pharyngoplasty in place at the time of osteotomy, effect of performing multiple jaw procedures, and maintenance of overjet and overbite were analyzed. Tracings of preoperative and serial postoperative lateral cephalograms (taken immediately and at 6 to 8 weeks and 1 year) were analyzed to calculate horizontal and vertical maxillary change and the amount of overjet and overbite maintained. Clinical follow-up ranged from 1.5 to 4.5 years (mean 1.5 years). No significant difference was seen in horizontal or vertical surgical change or relapse between patients who had maxillary surgery alone (n = 24) and those who had operations on both jaws (n = 11), nor did outcome vary significantly for those with a pharyngoplasty in place (n = 13) at the time of their Le Fort I osteotomy (p < 0.05). The mean effective horizontal advancement achieved for the group was 6.9 mm, with 5.3 mm maintained 1 year later (mean relapse of 1.6 mm). The mean effective vertical change of the maxilla was 2.1 mm initially and 1.7 mm 1 year later (mean relapse of 0.4 mm).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Frontonasal and craniofrontonasal dysplasia: preoperative quantitative description of the cranio-orbito-zygomatic region based on computed and conventional tomography.

The unoperated crano-orbito-zygomatic complex of 18 children (mean 4.7 years) with frontonasal dysplasia (FND) and 12 children (mean 1.1 years) with crainofrontonasal dysplasia (CFND) was quantified by 15 standard measurements performed on either computed tomography scans or facial tomograms. The results were compared with age-matched control values. In the FND group, the mean anterior interorbital and mid-interorbital distances were significantly increased at 148% and 118% of normal, and in the CFND patients, at 177% and 140% of normal. Excessive medial orbital wall protrusion (mean, 145% of normal in FND and 177% in CFND), shortened zygomatic arch lengths (mean, 94% of normal in FND and 91% in CFND), and reduced cephalic lengths (mean, 96% of normal in FND and 83% in CFND) were all observed. An expanded interzygomatic buttress distance was documented only in the CFND group, at 11% of normal. The clinical presentation of craniofacial deformities such as FND and CFND can be objectively described by a numerical analysis of the bony pathology.

Adolescent↗
PubMed1994

The craniofacial dysostosis syndromes. Current reconstructive strategies.

The author's preferred approach to the management of the craniofacial dysostosis syndromes is to stage the reconstruction to coincide with the facial growth patterns, visceral (brain and eye) function, and psychosocial development. Recognition for the need for a staged reconstruction approach serves to clarify the objectives of each phase of treatment for the surgeon, the craniofacial team, and the family unit. By continuing to define the rationale for the timing and extent of surgical intervention, then objectively evaluating both functional and morphologic outcomes, surgeons will further improve the long-term function and facial aesthetics for patients born with these complex syndromes.

Brain↗
PubMed1994

Apert syndrome: quantitative assessment by CT scan of presenting deformity and surgical results after first-stage reconstruction.

We reviewed our experience with eight infants or young children (less than 2 years of age) who presented sequentially with Apert syndrome. Using a method of 14 measurements taken from the cranio-orbitozygomatic region in preoperative and postoperative CT scans of these patients, we documented their presenting skeletal morphology and the results of surgical correction at least 1 year after surgery. Significant preoperative findings included a wide anterior cranial vault at 110 percent of normal, a maximum cranial length that averaged only 90 percent of normal, a substantially widened anterior interorbital distance of 117 percent of normal, an increased lateral interorbital distance (112 percent of normal), and a widened bitemporal width at 122 percent of normal. Globe protrusion was significant at 121 percent of normal, and the medial orbital wall distance (length) was less than normal at 92 percent. In the upper midface (zygomatic) region, both the distance between the zygomatic buttresses and the interarch distance were found to be increased at 109 percent of normal, while the zygomatic arch lengths were substantially shortened at 79 percent of normal. Results of surgical correction, as documented by CT scan measurements, showed that more than a year after surgery, skeletal morphology had changed from preoperative measurements but that none of the craniofacial measurements had significantly improved (p < 0.05) in comparison with those of age-matched controls. Quantitative measurement of CT scans of the cranio-orbitozygomatic region confirmed clinically observed findings in these patients before cranio-orbital reconstruction in infancy and early childhood and proved useful in assessing the surgical results over time.

Acrocephalosyndactylia↗
PubMed1994

Facial sensibility in adolescents born with cleft lip after undergoing repair in infancy.

Values for facial sensibility measured in 68 adolescents born with cleft lip who had undergone repair in infancy (39 unilateral cleft patients with a mean age of 17 years and 29 bilateral cleft patients with a mean age of 19 years) were compared to values of 22 noncleft controls (mean age 18 years). Static two-point discrimination results and cutaneous pressure thresholds were similar between controls and cleft patients. Vibratory threshold values were lower in cleft patients, with significant differences (p < 0.05) in the nasolabial and upper lip skin areas. These differences might indicate minor sensory abnormalities of the quickly adapting fibers, differences in the ability of the deformed maxillary bone of cleft patients to conduct impulses, or other potential errors in the vibrometer.

Adolescent↗
PubMed1994

Intracranial nasal dermoid sinus cysts: computed tomographic scan findings and surgical results.

From July 1987 to January 1991, 14 patients, ages 1 to 19 years (mean 6 years), were seen with nasal dermoid sinus cysts, a congenital lesion with the potential for intracranial extension. Each patient was assessed clinically for cyst location, symptoms, associated craniofacial deformity, and other congenital anomalies. In 5 (36 percent) of the 14 patients, ages 4 to 48 months (mean 25 months), computed tomographic scans indicated indirect signs of intracranial extension, which were confirmed intraoperatively and histologically in all 5 patients. After neurosurgical consultation, a combined single-stage intracranial-extracranial approach was used to excise the lesion. No perioperative complications occurred. Clinical assessment (follow-up 20 to 40 months, mean 31 months), confirmed by postoperative CT scan 1 year after surgery, indicated no evidence of recurrence, residual skeletal contour defects, or deformity; forehead and nasal growth were qualitatively normal, and scar appearance was satisfactory. Our experience indicates that intracranial extension of nasal dermoid sinus cysts seen at a tertiary care referral center are not rare, that computed tomography scan permits accurate diagnosis, and that the single-stage intracranial-extracranial approach to resection is effective and results in minimal morbidity.

Adolescent↗
PubMed1994

Fetal nerve healing: an experimental study.

An experimental study was performed to assess fetal nerve repair and regeneration both qualitatively and quantitatively. The posterior tibial nerves in one hindlimb were transected in 16 midgestational fetal lambs and in their mothers. The nerves were then repaired with epineurial sutures and allowed to progress to 2, 4, 6, and 8 weeks postinjury. Qualitative assessment was performed through standard nerve histologic staining, including Luxol fast and toluidine blue for myelin and Bielschowsky stain for axons, and quantitative assessment through nerve conduction velocity studies and morphometry to determine mean myelinated fiber diameter, total fiber number, and density. A frequency histogram of the distribution of myelinated nerve fibers according to fiber diameter also was generated. In our model, the subsequent fetal nerve response to injury was characterized by earlier degeneration than in the adult counterparts. Repair and regeneration proceeded with dense collagenous scar formation in both groups. Electrophysiologic studies showed nerve impulse conduction across the repair site only at 6 and 8 weeks postinjury in both fetus and adult. Action potential amplitudes at 6 and 8 weeks were measured at 3 to 5 percent of control nerves in both nerve types. No electrophysiologic differences in the recovery of the injured fetal and adult nerves could be identified. Morphometry revealed that fetal nerve regeneration appeared to occur at a rate equivalent to that of the adult, although by 8 weeks the total percentage of remyelinated nerves appeared more complete in the fetus than in the adult (87 versus 59 percent), suggesting that fetal nerves may have a more favorable regenerative capacity than their adult counterparts.

Action Potentials↗
PubMed1994

Metopic synostosis: quantitative assessment of presenting deformity and surgical results based on CT scans.

Our study applied a method of using 14 clinically relevant measurements of CT scan images to document skeletal dysmorphology in patients with metopic synostosis to determine the effectiveness of their surgical procedure after a minimum of 1 year. Ten consecutive patients with metopic synostosis who underwent a standard surgical procedure were reviewed. Preoperative and postoperative (> 1 year) CT scans were compared with those of age-matched controls. Percentages of normal were then compared for significant differences. Preoperative cranial vault measurements revealed a narrowed anterior intercoronal distance at 92 percent of normal. Orbital measurements showed a narrowed anteromedial wall interorbital distance at 79 percent of normal, a narrowed lateral orbital wall distance at 94 percent, and an elevated medial orbital wall protrusion beyond the plane of the lateral orbital walls at 115 percent. After surgery, the intercoronal distance was significantly corrected to 101 percent, the anteromedial wall interorbital distance was improved but remained undercorrected at 90 percent, and the medial wall protrusion was significantly decreased to 98 percent of normal. Quantitative measurements of CT scan images confirmed clinically observed physical findings in unoperated trigonocephaly to be orbital hypotelorism, retruded lateral orbital rims, and a narrowed bitemporal width. The surgical technique corrected the lateral orbital wall aspects of the deformity as well as the narrowed anterior cranial vault width and improved the orbital hypotelorism.

Cephalometry↗
PubMed1993

Triggering after partial tendon laceration.

Triggering and tendon flap formation were studied after a transverse laceration of 50% of the width of the flexor digitorum profundus tendons of the hind limb of 14 adult sheep at various intervals after injury. The tendon laceration was not repaired and there was no post-operative immobilization. Triggering was not caused by bulbous scar formation but by the bunching of the tendon fibres proximal or distal to the laceration site. This bunched part of the tendon appeared to become incorporated into the healing process, with gradual spontaneous resolution of triggering. Failure of incorporation of this bunched part resulted in the formation of a flap in two tendons.

Animals↗
PubMed1993

Pediatric facial fractures: evolving patterns of treatment.

This study reviews the treatment of facial trauma between October 1986 and December 1990 at a major pediatric referral center. The mechanism of injury, location and pattern of facial fractures, pattern of facial injury, soft tissue injuries, and any associated injuries to other organ systems were recorded, and fracture management and perioperative complications reviewed. The study population consisted of 137 patients who sustained 318 facial fractures. Eighty-one patients (171 fractures) were seen in the acute stage, and 56 patients (147 fractures) were seen for reconstruction of a secondary deformity. Injuries in boys were more prevalent than in girls (63% versus 37%), and the 6- to 12-year cohort made up the largest group (42%). Most fractures resulted from traffic-related accidents (50%), falls (23%), or sports-related injuries (15%). Mandibular (34%) and orbital fractures (23%) predominated; fewer midfacial fractures (7%) were sustained than would be expected in a similar adult population. Three quarters of the patients with acute fractures required operative intervention. Closed reduction techniques with maxillomandibular fixation were frequently chosen for mandibular condyle fractures and open reduction techniques (35%) for other regions of the facial skeleton. When open reduction was indicated, plate-and-screw fixation was the preferred method of stabilization (65%). The long-term effects of the injuries and the treatment given on facial growth remain undetermined. Perioperative complication rates directly related to the surgery were low.

Accidents, Traffic↗
PubMed1993

Fetal bone gap healing in utero.

The healing of fetal tibial bone after osteotomy with and without stable fixation has been reported previously. The present study was designed to evaluate fetal bone gap healing using a tibial ostectomy model in fetal sheep. Eighteen time-dated pregnant ewes (20 fetuses, 34 experimental hind limbs) underwent intrauterine surgery at 95 days gestation (term, 145 days). A titanium miniplate was applied to the anterior aspect of the tibia and a longitudinal length of bone approximately 1.5 times its diameter was removed and the incision closed. The pregnancies were then allowed to progress until the ewe was killed at postoperative weeks 1, 2, 4, or 7. Assessments at that time included evaluation of gross morphology, histologic and radiologic appearance, and collagen analysis and hydroxyproline determination of the tissue within and at the borders of the gap. At 7 weeks, seven of nine bone gap specimens exhibited radiographic and histologic evidence of union with woven and lamellar bone. Hydroxyproline concentrations gradually increased within the bone gap over the period of the study. At all intervals, type I collagen composed over 90% of the collagen within the healing bony gap. Histologically and biochemically, the process appears to be similar to postnatal bone healing, albeit occurring at an accelerated rate.

Animals↗
PubMed1993

Modification of the maxillary Le Fort I osteotomy in cleft-orthognathic surgery: the bilateral cleft lip and palate deformity.

The adolescent with bilateral cleft lip and palate (BCLP) undergoing orthognathic surgery may have multiple residual clefting problems, including a mobile, dysplastic premaxilla and hypoplastic lateral maxillary segments, with each segment misaligned in three dimensions. These problems are commonly compounded by residual oronasal fistulas, bony defects, soft-tissue scarring from previous surgery, and the congenital absence of the maxillary lateral incisor teeth with resulting cleft-dental gaps. This article describes modifications of the Le Fort I osteotomy that allow for the simultaneous routine and safe management of these deformities. Results of this operation on 22 consecutive patients are reported, with findings of follow-up ranging from 1 to 5 years. The long-term parameters reviewed include closure of residual oronasal fistulas, stabilization of the premaxilla, cleft-dental gap closure, maintenance of attached gingiva at the cleft site, maintenance of a positive overjet and overbite, the need for prosthetics to complete dental rehabilitation, and surgical morbidity.

Adolescent↗
PubMed1993

Extensive malignant melanoma of the uvea in childhood: resection and immediate reconstruction with microsurgical and craniofacial techniques.

Malignant melanoma is a rare tumor in the pediatric age group. Those that have been reported generally describe cutaneous lesions. In children, malignant melanoma arising in the eye is exceedingly rare. The child we report was born with a uveal tract malignant melanoma with extensive extraocular invasion that was successfully managed with combined craniofacial and microsurgical techniques. This patient demonstrates the difficulty of making the correct diagnosis, the initial reluctance about surgical intervention in a newborn's condition, and the subsequent success possible with standard microsurgical and craniofacial techniques.

Facial Bones↗