Biomedical subjects

P Alberius

Publications and source records attributed to P Alberius.

At least 55 records · Page 3Linked to original sources

PubMed1989

Body weight gain as related to craniofacial and calvarial volumetric changes in growing rabbits.

This investigation was conducted to evaluate the relationship between calvarial and craniofacial volumetric growth relative to body weight gain. Ten male New Zealand white rabbits received spherical tantalum bone markers in the nasal, frontal, parietal, and temporal bones: a minimum of two in each bone segment. The animals were followed from age 32 to 144 days using a roentgen stereophotogrammetric system and an accurate scale. Implant stability was checked at each stereometric examination. Sutural growth and volumetric changes were computed and correlated to weight increase. Successive calvarial and craniofacial polyhedron expansion, as well as weight, showed considerable variability and interindividual variation throughout the observation period. Calculated coefficients of determination, linear regressions, and the correlation coefficients for each age interval demonstrated weak correlations, especially for calvarial to weight data. Consequently, this study suggests a low dependence of calvarial volumetric growth, reflecting the neural mass expansion on body weight development. Thereby, further indications of the low reliability of weight as a parameter of general health evaluation was provided.

Animals↗

PubMed1989

Management of craniotomy in young rabbits.

A safe and easy-to-manage technique for various craniotomy procedures in young rabbits has been developed. This technique, which minimizes the need for special instrumentation, has been tested in 90 animals with a minimal mortality and morbidity: one death perioperatively caused by sagittal sinus bleeding and one rabbit disclosing a brief period of postoperative illness, respectively. The technique, including postsurgical strategy, is described in detail.

Animal Welfare↗

PubMed1987

Relationships between growth at the sutures of the rabbit calvarium.

The present study was designed to elucidate the relationships between growth increments at the cranial vault sutures in rabbits. Thirteen male New Zealand white rabbits were followed regularly from age 31 to 142 days using a roentgen stereophotogrammetric system. Spherical tantalum markers were implanted into the nasal, frontal, and parietal bones, and implant stability was checked at each stereo examination. Problems with instability were encountered only in the nasal bones. Registered growth rates conformed to our previous investigations. High correlations were observed between the following areas; the coronal suture to the frontonasal suture, the first principal component of the neurocranial suture group to the frontonasal suture, and the principal component of the craniofacial suture group to the coronal suture. Remaining relationships demonstrated dispersion to various extents. The findings indicate that there seems to exist a basic mutual dependence between neural and facial skeletal growth, as well as complex covariations between the various sutures of the rabbit calvarium.

Animals↗

PubMed1987

Cranial suture growth as correlated with weight gain in rabbits.

The association of skull growth to weight gain is essential in biometric investigations for correct interpretation of registered results. This was studied in 16 male New Zealand white rabbits aged between 32 and 143 days using roentgen stereophotogrammetric analysis for measurements of cranial suture growth increments and an accurate scale for weight controls. Skull growth decreased continuously with time apart from the first interval; weight changes varied. Calculated coefficients of determination, linear regressions, and the correlation coefficients for each age interval demonstrated weak correlations. No significant difference between the facial and neurocranial skeleton relative to weight was discerned. The low dependence of cranial variables on weight, as well as the fluctuating weight development, imply a need of great wariness in assessing health conditions by weight registration solely.

Animals↗

PubMed1987

Calvarial growth after linear craniectomy in scaphocephaly as evaluated by X-ray stereophotogrammetry.

An roentgen stereophotogrammetric system for the evaluation of skeletal adjustments following corrective surgery in craniosynostosis is described. Four illustrative cases of scaphocephaly, all treated with midline linear craniectomy, with uneventful postoperative follow-up periods of more than 4 years, are reported. The postoperative development, as evaluated by volumetric and kinematic analyses, was uniform but still rich in individual and local growth variations. This study confirms that roentgen stereometry ( = exact measurements from stereoradiographs), being an accurate and objective method, adds greatly to previous methods of postoperative assessment in craniofacial skeletal disorders.

Biomechanical Phenomena↗

PubMed1987

Effects of bone wax on rabbit cranial bone lesions.

The present study was designed to elucidate the reactions of cranial membranous bone to bone wax. In ten young rabbits, twenty parietal bone defects were created by drilling, the edges of which were partly extended using rongeur forceps to enable investigation of eventual thermal effects. Half of the marginal bone surrounding the lesions was covered by bone wax, the remainder serving as control. The animals were sacrificed 1 and 7 weeks after surgery, and block specimens prepared for light microscopy. Merely slight tissue reactions to the bone wax were discerned. Bony regeneration occurred mainly from the dura mater and the pericranium, but also from the bony rim. Reskeletalization was markedly impaired by the presence of bone wax. Heat generated by drilling caused reduced bone formation despite constant irrigation peroperatively. Clinical consequences are discussed.

Animals↗

PubMed1986

The correlation between craniofacial and long bone growth: an experimental investigation in normal rabbits.

The present study was undertaken to elucidate the relationships between craniofacial and long-bone growth. Nine male New Zealand white rabbits received spherical tantalum bone markers in the tibial epiphyses and in the nasal, frontal, and parietal bones. The animals were followed from 30 to 143 days of age. Growth changes were calculated with a roentgen stereometric system, and the results statistically evaluated. Except for the final interval when all variables varied at random, high correlations between tibial and frontonasal or coronal sutural growth were demonstrated; and the respective linear regression lines were homogeneously assembled. The relationship between the tibia and the sagittal suture displayed great variations between individual animals as well as between the suture's parts, although growth at the interfrontal suture was clearly correlated to tibial growth upon exclusion of the time factor. The first principal component of the three neurocranial sutures was calculated and seemed accurately correlated to long-bone growth. The present study concluded that growth at the frontonasal and coronal sutures normally seems to parallel general somatic development, while growth at the sagittal suture appears individually displaced in time. Nevertheless, when the principal component of the combination of the coronal suture and the neurocranial section of the sagittal suture was computed, this was highly correlated to body growth.

Age Factors↗

PubMed1986

The use of Zenker's solution in linear craniectomy for craniosynostosis: technical modification and reappraisal.

Regrowth of bone after craniectomy for craniosynostosis is still a problem, despite the advent of newer and extensive surgical techniques. A clinical study on 25 consecutive patients was undertaken to determine whether a modification of previous routines could retain the advantages of a tissue fixative, Zenker's solution, while eliminating the drawback of convulsive activity. After brief coagulation, Zenker's solution was sparingly applied to the dural surface for maximally one minute followed by copious irrigation of the surgical field. The results were satisfactory and postoperative complications unrelated to the fixative. The present procedure seems safe, effective, and easy to use.

Bone Regeneration↗

PubMed1986

Roentgen stereophotogrammetry for analysis of cranial growth.

A system of roentgen stereophotogrammetric analysis (RSA) has been developed and its value in studies of cranial growth in both man and the experimental animal (rabbit) has been delineated. This method is based on measurements from metal bone marker images on roentgenograms. Two roentgen tubes simultaneously expose the object, which is placed in one of two types of calibration cages. The object position does not need to be identical from one examination to the next. The cage, holding indicators of predetermined internal positions (in two or four planes), defines a laboratory coordinate system. Two-dimensional image coordinates are obtained by means of a highly accurate cartographic instrument. By computer reconstruction of the x-ray beams through the markers, 3-D object coordinates are calculated. For subsequent analysis of growth processes, extensive software is necessary. To control intrasegmental stability (routinely performed at each examination), a minimum of two markers is required, whereas three markers are needed in each skeletal segment for kinematic analysis using the rigid-body concept. Careful planning of marker placement before implantation minimizes implant loss and instability that otherwise might be a problem. Complications other than bone marker loosening have been nonexistent. The technical accuracy is high. Consequently, roentgen stereophotogrammetry, with the aid of metallic implants, is a superior means to obtain biometric information on cranial growth with relative ease.

Animals↗

PubMed1986

Growth of calvarial width. An experimental investigation in rabbits.

This investigation was conducted to analyze growth in width of the rabbit calvarium. 15 male New Zealand white rabbits were subjected to regular stereometric examinations from 31 to 141 days of age after implantation of tantalum bone markers. The sagittal suture complex, i.e. the interfrontal and interparietal sutures, and the bilateral temporal sutures demonstrated similar growth rates in magnitude which moderately decelerated throughout the observation period. Transverse growth exhibited local growth fluctuations and short-term negative growth values in a well-balanced manner.

Animals↗

PubMed1986

Postnatal sutural growth of the calvarium: a survey with special reference to the rabbit.

The postnatal development of the cranial vault is reviewed with special emphasis upon the rabbit in respect to longitudinal, volumetric, and kinematic growth. Also, the calvarial growth relative to long bone growth is discussed. The cranial vault suture is a multifunctional syndesmosis with variable structure and a rich variability of local behavior.

Animals↗

PubMed1986

Long-term analysis of calvarial growth in rabbits.

Knowledge of normal suture development is vital to the understanding of aberrant suture growth. The purpose of the present investigation was to comprehensively analyze the complete growth period of the calvarium in rabbits, thus including increment beyond maturity (20 weeks). 5 male New Zealand white rabbits were studied from age 14 d until cessation of cranial growth using roentgen stereophotogrammetry. Growth at the coronal and sagittal sutures seemed completed at 8 months of age, while the frontonasal suture still exhibited minute expansion at the end of the observation period (13 months). Coronal suture growth decelerated linearly relative to the frontonasal suture. Bone separation at the sagittal suture varied less with age as compared to that of the transverse sutures. A brief period of growth reduction, pertaining to all cranial vault sutures, during the second interval (d 35-42) corresponded well with cessation of weaning. Balanced growth fluctuations were frequent. Spatial alterations correlated well with longitudinal increments as to growth arrest. Changes of rotational direction during active growth as well as, in some cases, widespread variations between individuals demonstrated the flexibility of angular calvarial development. In conclusion, the registered growth activity beyond maturity craves consideration during the evaluation of experimental changes of sutural growth so as not to disregard compensatory adjustments.

Animals↗

PubMed1985

Volumetric changes in the developing rabbit calvarium.

Tantalum bone markers were implanted in the frontal, parietal, and temporal bones, at least two in each bone segment, in seven male New Zealand white rabbits. Roentgen stereophotogrammetric analyses were performed for regular intervals between ages 30 to 142 days. With the exception of a few implants in the temporal bone, bone markers remained stable during the observation period. Volumetric and longitudinal growth data were compared. Calvarial polyhedron volumes increased linearly. Growth at the actual neurocranial sutures demonstrated an individually fluctuating pace. No obvious correlation between volumetric and longitudinal growth was noted. This might be explained by sagittal and temporal suture growth in periods being close to the methodological error and failure to document bone rotations. Previous observations on the linearity in cerebral weight increase during corresponding periods of time points to the decisive role of neural mass growth in calvarial development in rabbits. Suture growth characteristics are discussed.

Animals↗

PubMed1985

Tantalum markers in radiography. An assessment of tissue reactions.

The biocompatibility of two types of radiopaque tantalum markers was evaluated histologically. Reactions to pin markers (99.9% purity) and spherical markers (95.2% purity) were investigated after 3-6 weeks in rabbits and 5-48 weeks in children with abnormal growth. Both marker types were firmly attached to bone trabeculae; this was most pronounced in rabbit bone, and no adverse macroscopic reactions were observed. Microscopically, no reactions or only slight fibrosis of bone tissue were detected, while soft tissues only demonstrated a minor inflammatory reaction. Nevertheless, the need for careful preparation and execution of marker implantations is stressed, and particularly avoidance of the use of emery in sharpening of cannulae. The bioinertness of tantalum was reconfirmed as was its suitability for use as skeletal and soft tissue radiographic markers.

Animals↗

PubMed1984

Roentgen stereophotogrammetric analysis of neurocranial suturectomy in rabbits.

This investigation was conducted to further elucidate both the significance of a calvarial suture and the compensatory ability of the cranial vault. Four-week-old male New Zealand White rabbits were subjected to unilateral or bilateral extirpation of the coronal suture after insertion of metallic markers, and were then followed regularly by roentgen stereophotogrammetry until age 21 weeks. Bilateral extirpation of the normal coronal suture resulted in a dramatically increased initial rate of bone separation, which tended to remain supranormal for the rest of the investigation. Unilateral suturectomy showed differences in growth between the sides, the operated side initially separating significantly more than the other. Volumetric calvarial growth in rabbits with unilateral extirpation terminated similar to that in control animals, while volumes in rabbits with bilateral extirpations constantly exceeded control volumes, finally exceeding these by 65%. Responses at intact sutures confirmed the compensatory capacity of cranial vaults. The results indicate that the passive longitudinal and volumetric cranial vault bone growth responds quickly to growth disturbances, thereby demonstrating its plasticity, and that the neurocranial suture is a restraining and modulating component in cranial growth.

Animals↗

PubMed1984

Roentgen stereophotogrammetric analysis of restricted periods of neurocranial suture immobilization in rabbits.

The effect of temporary fusion of sutures on craniofacial growth was studied biometrically in 4-week-old male New Zealand White rabbits. Tantalum bone markers were implanted in the cranial vault, and the coronal suture immobilized with isobutyl-2-cyanoacrylate adhesive. Linear craniectomy was performed after 2 or 6 weeks of sutural growth restriction (four animals in each group). The animals were followed for approximately 17 weeks. Early craniectomy resulted in greatly increased coronal suture bone separation (175% of control growth rates in peers and 125% of maximal control rates). Growth after late craniectomy showed an age-dependent lower rate, but still the overshoot markedly surpassed controls (210% of control rates in peers and 65% of maximal control growth rates). Overall, both exhibited overcompensation in coronal suture growth. A rapid compensation of adjacent sutures to temporary growth restriction and a tendency toward spontaneous correction following release of growth inhibition were demonstrated. Thus, the total anteroposterior growth of the combined frontonasal and coronal sutures nearly equaled that of control animals. Following linear craniectomy, volumetric calvarial expansion increased considerably in both early and late groups, due to compensatory coronal suture growth, but probably due also to spatial bone rearrangements. Based upon the findings, the length of the suture immobilization period seems critical to longitudinal and volumetric growth as well as to subsequent compensatory activity after surgical correction.

Animals↗

PubMed1983

Kinematics of cranial vault growth in rabbits.

To characterize mathematically the spatial rearrangement of cranial vault bones of the rabbit during growth, a longitudinal study was undertaken from age 4-20 weeks. Initially, at least three nonlinear tantalum bone markers were implanted in the parietal, frontal, and the combined nasal bones. Thereafter, the animals were followed regularly with roentgen stereophotogrammetrical analysis. The parietal bones were found to rotate laterally upward (3 degrees), while the frontal bones rotated downward (2 degrees) relative to their contralaterals. The frontal bones rotated rostrally upward (12 degrees) and outward (3 degrees) as well as laterally downward (5 degrees) in relation to the parietal bones. Due to the morphology of the rabbit head, the examination positioning used in this study, and the direction of the growth process, growth at the coronal suture correlated fairly well with longitudinal axis translations; but the growth at the frontonasal suture relative to the frontal bones was directed about 45 degrees downward. This points to the importance of the bone-marker positioning, so that their connecting line is directed along the axis of growth. Also, this approach makes it possible to obtain new information on the development and treatment of craniofacial aberrations.

Animals↗

PubMed1983

Bone reactions to tantalum markers. A scanning electron microscopic study.

To elucidate intramembranous bone reactions to tantalum bone markers, 0.8-mm tantalum balls were implanted in the craniofacial region of 9 male New Zealand white rabbits. After 1, 2, 4 and 16 weeks the animals were sacrificed for SEM. Implant stability for these intervals was controlled by roentgen stereophotogrammetry. Fibrocytes and deposed fibers were seen to immediately adhere to the ball surface, getting retention in its porosities. A successively increasing bony support was observed to have intimate junctions without intervening fibers or soft tissues. No apparent differences in bone reactions were seen between the neurocranial and splanchnocranial bones. Osseointegration confirmed the inertness of tantalum to bone tissue and strongly confirms its suitability for implantation in bone.

Animals↗