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Biomedical subjects

G Selvik

Publications and source records attributed to G Selvik.

At least 109 records · Page 6Linked to original sources
PubMed1979

Motion of bones and volume changes in the neurocranium after craniectomy in Crouzon's disease. A roentgen stereometric study.

Craniectomy was performed on a boy with Crouzon's disease at 22 months of age. Metallic implants (tantalum balls, 0.5 mm in diameter) were inserted in the calvaria during surgery, and the child was examined postoperatively by roentgen stereometry at intervals of about 100 days (total observation time, 309 days). The thyroid radiation dose was 250 muGy for one examination. The effect of craniectomy was recorded with a high degree of accuracy in terms of motion of bones and volume changes in the calvaria. Expansion occurred almost entirely through motion of free bone flaps in the frontal region, while a linear craniectomy in the region of the sagittal suture caused small changes. The rate of expansion decreased rapidly and stabilization was recorded about 250 days after surgery.

Bone Development↗
PubMed1979

A roentgen stereophotogrammetric study of implant stability and movement of segments in the maxilla of infants with cleft lip and palate.

Three implants (tantalum pins 1.5 x 0.5 mm) were inserted in each lateral segment of the cleft maxilla of ten infants aged three to 33 months. To check the stability of the implants in the bone the distances between the three implants within each segment were measured by means of roentgen stereophotogrammetry (accuracy 0.05 mm) at intervals of 7, 35, 63, 147, and 287 days after initial examination and at varying intervals thereafter (maximal observation time 833 days). No implants were lost and 18 of 60 measured distances were stable (final changes less than 0.2 mm). The three implants were regarded as a rigid-body model which represented the segment in the calculations of motion. In all infants with complete clefts, transverse narrowing occurred immediately after primary closure of the lip, or primary palate repair, while subsequent movement followed individual patterns.

Child, Preschool↗
PubMed1979

Oral orthopedics and movement of maxillary segments. A roentgen stereophotogrammetric study.

An infant with a complete unilateral cleft of the lip and palate underwent maxillary expansion treatment using an oral orthopedic appliance. Movement of the maxillary bone segments was studied by means of metallic implants and roentgen stereophotogrammetry, and intra-oral changes were recorded by measuring transverse dimensions on casts. Expansion treatment had almost no influence on the positions of the maxillary segments, and movements of the segments showed little agreement with measures on casts. The findings suggest that the appropriate use of the term oral orthopedics and the evaluation of treatment effects would benefit from evaluating the movement of the segments by methods other than measurements of casts.

Cleft Lip↗
PubMed1978

Roentgen stereophotogrammetry for evaluation of liver volume and shape.

Model experiments and tests on 2 patients were performed to probe the feasibility of roentgen stereophotogrammetry for evaluating variations in shape and volume of the liver. The surface of the object was marked with indicators, and the three-dimensional marker coordinates were determined. The model experiments demonstrate a good correlation between true volume and the volumes defined by the indicators, and also demonstrate the possibility of localizing an expansivity. The variability of the volume of a polyhedron defined by 15 liver indicators with stage of breathing is discussed.

Computers↗
PubMed1978

Movements in the sacroiliac joints demonstrated with roentgen stereophotogrammetry.

Using a roentgen stereophotogrammetric method, the three-dimensional movements in the sacroiliac joints were quantified in 4 patients. To provoke motion of the sacrum, changes between body positions and a test with manual pressure were used. In tests with symmetric forces on the sacrum, it in most cases rotated mainly about a transverse axis and at most approximately 2 degrees. The axis of rotation passed through the iliac bones mainly in the lower part of the iliac tuberosity. The rotations between the iliac bones and the sacrum about any of the three main axes were determined with a precision in the mean of 0.2 degrees. The distance between the two superior posterior iliac spines varied at most 0.4 mm between seven different body positions.

Adult↗
PubMed1978

Roentgen stereophotogrammetry for determination of daily longitudinal bone growth in the rabbit.

The spatial location of points in an object can be determined by roentgen stereophotogrammetry. A technique of high accuracy was applied in a determination of the daily skeletal growth of young rabbits. The tibia was labelled with tantalum markers on each side of the growth zones, and the increasing distance between these markers due to longitudinal bone growth was measured. Three different types of markers were tested, and the methodologic error was estimated. It varied between 30 and 43 micrometer for one growth interval, depending on the type of marker used. The method has clinical implications currently under investigation.

Animals↗
PubMed1978

A roentgen stereophotogrammetric investigation of innominate osteotomy (Salter).

The effect of the innominate osteotomy according to Salter was investigated by a roentgen stereophotogrammetric method in a 17-year-old girl with hip dysplasia as a part of the tricho-rhino-phalangeal (Giedion) syndrome. The osteotomy resulted in a total rotation of 32 degrees about an axis passing cranially to the pubic symphysis and the osteotomy. The acetabulum rotated 22 degrees forwards about a transverse axis, 9 degrees laterally about a longitudinal axis and 24 degrees laterally about a sagittal axis. The acetabulum was translated 2 mm laterally along a transverse axis, 21 mm caudally along a longitudinal axis and 19 mm dorsally along a sagittal axis. The position of the screw axis indicates that some motion also took place in one or both of the sacroiliac joints. The correction as measured with the CE-angle was 25 degrees which was almost the same as the correction about the sagittal axis. It is, however, noted that the CE-angle was also dependent upon the rotations about the transverse and longitudinal axes.

Adolescent↗
PubMed1978

Antineoplastic-drug effect evaluated with a new X-ray stereophotographic measurement of the tumour volume.

A method for determination and follow up of the size of inoperable intraabdominal tumours has been devised. At laparotomy, tantalum balls are deposited into the capsule of the tumour. An X-ray stereophotogrammetric method determines their position, which define a polyhedron whose volume can be computer calculated. The value of the method was proved in four patients with inoperable ovarian carcinoma, which provides a simple way for the continuous follow up of the effect of antineoplastic therapy in advanced malignant tumours.

Abdominal Neoplasms↗
PubMed1977

Postoperative kinematics in structural scoliosis.

Three cases with idiopathic, structural scoliosis were examined postoperatively with a roentgen stereophotogrammetric method. Curvatures developed in both the frontal and sagittal planes. Axial rotation also occurred. In addition, residual mobility was demonstrated and quantified one year postoperatively.

Adolescent↗
PubMed1977

Roentgen stereophotogrammetry for determination of bone growth. Comparison with the tetracycline method.

Two different methods for determination of leg growth, the tetracycline method and roentgen stereophotogrammetry, were applied simultaneously in 41 young rabbits and compared 1 and 2, and 21 and 22 days after insertion of pins or balls of tantalum as markers. The tetracycline method gave slightly higher values than the other method, the difference varying between 77 and 6 micrometer/d on the first 2 days after marker insertion and between 32 and 1 micrometer/d after 3 weeks. When ball markers were used, agreement between the two methods was obtained 3 weeks after insertion. The difference between the methods used is due to that the two methods did not measure growth in precisely identical regions.

Animals↗
PubMed1976

Kinematic analysis of posterior spinal fusions in pigs.

Five pigs operated upon by posterior spinal fusion were examined by a roentgen stereophotogrammetric method during provoked motion. The healing process leading to marked rigidity within the spine was followed in two of the pigs. Varying degrees of stability in the fused area were achieved in the five animals. Movements were detected, not only when the fusions were not healed, but also in two cases of incomplete bony union between two operated segments.

Animals↗
PubMed1976

Kinematic analysis of posterolateral fusion in the lumbosacral spine.

Three cases operated upon with posterolateral fusion in the lumbosacral spine have been subjected to a kinematic postoperative analysis with the aid of a roentgen stereophotogrammetric method. The primarily diseased intervals became comparatively rigid in spite of significant residual mobility, in two of the patients, not until 174 days postoperatively. Three levels of operation displayed unrestricted residual mobility.

Adult↗