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Biomedical subjects

G Selvik

Publications and source records attributed to G Selvik.

121 records · Page 7Linked to original sources
PubMed1976

Bone growth in the rabbit after irradiation.

The effect on bone growth of two locally given, different, unfractionated radiation doses (0.1 and 24 Gy) was tested in a rabbit litter aged 57 days. The effects on growth were registered with roentgen stereophotogrammetric length measurements for 75 days after irradiation. Growth of the right irradiated tibia was compared with the growth of the left non-irradiated tibia. After 7 to 9 days, 24 Gy had caused a linear fall in growth to about 15 per cent. After a period of complete cessation, a slight growth was registered. 0.1 Gy had no significant growth retarding effect.

Age Factors↗
PubMedDate not supplied

Kinematic analysis of spinal fusions.

Two cases with clinical suspicion of incompletely healed anterior fusion between L5 and S1 were examined by means of a roentgen stereophotogrammetric method. In both cases a pseudarthrosis was found. The method makes it possible to disclose rotations and translations between veretebrae with an accuracy of about 0.2degree and 30-120 mum, respectively.

Biomechanical Phenomena↗
PubMedDate not supplied

Longitudinal growth of the distal fibula in children with slipped capital femoral epiphysis.

The longitudinal growth rates of the distal fibula were measured, using a roentgen stereophotogrammetric method, in 32 children treated for slipped capital femoral epiphysis and compared with growth rates in a series of normal children. The growth rates in patients were similar to the growth rates in normal children, in both boys and girls. However, at the time of slippage, 13 patients had a body height exceeding the normal value by greater than 1 SD, indicating an above-average growth rate before slippage. This pattern was found in one boy whose distal fibular growth rates were measured both before and after slippage. In conclusion, there are indications that the skeletal growth rate is slightly accelerated before slippage and more normal after slippage.

Adolescent↗
PubMedDate not supplied

Space orientation of total hip prosthesis. A method for three-dimensional determination.

A method for in vivo determination of orientation and relation in space of components of total hip prosthesis is described. The method allows for determination of the orientation of the prosthetic components in well defined anatomic planes of the body. Furthermore the range of free motion from neutral position to the point of contact between the edge of the acetabular opening and the neck of the femoral component can be determined in various directions. To assess the accuracy of the calculations a phantom prosthesis was studied in nine different positions and the measurements of the space oriented parameters according to the present method correlated to measurements of the same parameters according to Selvik's stereophotogrammetric method. Good correlation was found. The role of prosthetic malpositioning and component interaction evaluated with the present method in the development of prosthetic loosening and displacement is discussed.

Arthrography↗
PubMedDate not supplied

Chronic anterolateral instability of the knee. A roentgen stereophotogrammetric evaluation.

The rotatory stability of the knee was investigated in 20 patients with a previous tear of the ACL. The three-dimensional movements of the tibia during the testing procedure were registered using roentgen stereophotogrammetric analysis. Changes of the tibial movements between an intermediate, an anterior, or a posterior tibial position were registered using tibial tractions in combination with a simultaneous external or internal rotatory torque. At 20 degrees of flexion the internal rotatory laxity was increased on the injured side. The external rotatory laxity did not significantly differ between the two sides. With anterior traction, the internal rotatory laxity increased on both the injured and the normal sides and became almost equal. The external rotatory laxity manifested a decrease which was most pronounced on the injured side. With posterior traction, the rotatory laxities decreased and did not significantly differ between the two sides. Analysis of the simultaneously occurring translations of the tibial plateau disclosed abnormal displacements of both the medial and the lateral tibial condyles on the injured side.

Chronic Disease↗
PubMedDate not supplied

Roentgenologic assessment of spondylolisthesis. II. An evaluation of progression.

Different degrees of artificial L5-S1 spondylolisthesis were created using a lumbar specimen. Lateral radiographs were obtained of each, with the specimen tilted and/or rotated. The true spondylolisthesis was determined stereophotogrammetrically. The slip, measured on the radiographs, was calculated according to two methods modified from Boxall et coll. No significant difference in accuracy was found between these two methods. The difference in calculated slip between examinations needs to be at least 20 per cent of the sagittal length of L5 to be regarded as a true progression. A true progress of slip of less than 20 per cent is difficult to detect with statistical certainty.

Cadaver↗
PubMedDate not supplied

Comparison of two- and three-dimensional methods for assessment of orientation of the total hip prosthesis.

A comparison of two- and three-dimensional methods for the determination of the orientation of total hip prostheses was made in a group of 57 patients. The acetabular inclination and the collum-diaphyseal angle measured on a.p. projections (2-D) were adequate in most cases for assessing how vertically the prosthetic component was inserted, but in individual cases with a high degree of version these measurements could be misleading. Anteversion measured in the transverse plane (2-D) was more sensitive to errors than planar anteversion measured as a rotation around the longest diameter of the ellipsoid projection of the acetabular opening, but it gave a rough estimate of the relation of the prosthetic components. Determination of the spatial (3-D) orientation of the components provides a precise estimate of the component relations.

Acetabulum↗
PubMedDate not supplied

Femoral anteversion and restricted range of motion in total hip prostheses.

Impingement of the neck of the stem on to the rim of the socket may cause dislocation of the total hip prosthesis. The role of femoral anteversion in the occurrence of such impingement was analyzed in a clinical material of total hip prostheses with and without dislocation. A low femoral anteversion was linked to a clinically relevant reduction of the range of motion due to impingement and dominated in the group with dislocations. Impingement is minimized by inserting the femoral component in 10 degrees to 20 degrees of anteversion.

Aged↗
PubMedDate not supplied

Range of motion caused by design of the total hip prosthesis.

In a clinical material of total hip prostheses, a study was performed of the range of femoral motion until impingement occurred between the neck of the femoral stem and the rim of the acetabular socket. The results were compared with the physiologic range of motion, and the clinically relevant motion restriction was measured. Restriction was most common in flexion. There was a correlation between the prosthetic design and the restriction due to impingement.

Aged↗
PubMedDate not supplied

Position, orientation and component interaction in dislocation of the total hip prosthesis.

The position, orientation in space and interaction of prosthetic components was determined in 15 patients with known episodes of dislocation after total hip replacement. The same calculations were performed in a reference group of 44 patients without dislocation. In the group with dislocations, there was a significantly decreased femoral anteversion, and a decreased femoral flexion permitted by the prosthetic components. There were no further significant differences of clinical relevance between the groups concerning all other examined parameters of component position, orientation and interaction. It is concluded that the decreased range of flexion, caused by impingement of the prosthetic components with ensuing leverage effect is one cause of dislocation.

Aged↗
PubMedDate not supplied

Mobility in the lumbosacral spine after fusion studied with the aid of roentgen stereophotogrammetry.

Twelve cases operated upon with fusion in the lumbosacral spine were studied with a roentgen stereophotogrammetric method. With this method the movements in the area supposed to be fused can be studied with high accuracy in 3 dimensions. The precision is 0.3 degrees for the rotation about the x-axis (transversal axis), 0.2 degrees for the rotation about the y-axis (longitudinal axis), and 0.1 degrees for that about the z-axis (sagittal axis) and of the magnitude of 0.1 mm for the translations. It was found that the possible stabilization of a fusion takes place within 180 days. The supposed gain of internal fixation with a sacral bar device was not verified. It was recommended that the supine and erect standing positions should be investigated and compared with this method and that standing with flexion should be added as soon as the healing process is supposed not to be injured by flexion movements.

Adolescent↗