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Biomedical subjects

G Selvik

Publications and source records attributed to G Selvik.

At least 19 recordsLinked to original sources
PubMed1994

Growth as a parameter of inflammation in Crohn's disease, using roentgen stereophotogrammetric analysis.

Growth rate was measured in 12 children with Crohn's disease and growth retardation, using roentgen stereophotogrammetric analysis. The method was chosen as it provides an opportunity to record growth rate accurately during short periods of time. Growth was followed at variable intervals of 4-12 weeks depending on the clinical situation. Growth rate was shown to correlate with symptoms, laboratory tests and nitrogen balance. These findings indicate that growth, when it is affected, fluctuates in a similar way as albumin, acute phase proteins and symptoms, all assumed to reflect the disease activity. Short-term growth measurements appear to be helpful in monitoring the disease progress or response to therapy in children with Crohn's disease, particularly when growth retardation is the only manifestation of the disease.

Adolescent↗
PubMed1993

Socket wear assessment. A comparison of three different radiographic methods.

Three different methods to measure wear of total hip sockets from plain radiographs were compared with the results obtained by direct assessment of the internal deformity of 28 retrieved sockets by means of a coordinate measuring machine. The values obtained by the uni-radiographic, the duo-radiographic, and the radiographic methods based on the change of distance between the centers of the socket and the prosthetic head (CEN) all correlated significantly with the standard obtained by the coordinate measuring machine, provided the sockets were not loose. The most accurate radiographic measurements were obtained with the CEN method. A prerequisite for a reliable estimation of socket wear rate is that it be based on observations of radiographically intact sockets.

Hip Joint↗
PubMed1992

The influence of metal backing in unicompartmental tibial component fixation. An in vivo roentgen stereophotogrammetric analysis of micromotion.

The fixation of the tibial component in 36 patients with conventionally cemented unicompartmental knee arthroplasties for femorotibial gonarthrosis was studied using roentgen stereophotogrammetric analysis (RSA). Twenty-four tibial components were all-polyethylene while 12 were metal-backed. The follow-up was for 6 years. Significant migration was detected for all cases but two and ranged from 0.3 mm to 5.4 mm. The greater part of the migration occurred during the first 1-2 years, after which two-thirds of the prostheses remained stable. Seven all-polyethylene components were subjected to a stress examination after 1-2 years and displacement, induced by external forces, was found in all seven. A strong correlation was found between the extension of the radiolucent line and the migration. Otherwise, neither demographic, clinical, nor radiographic data correlated with the RSA results. In this study metal backing did not have any influence on prosthetic fixation as measured by RSA.

Aged↗
PubMed1992

Influence of spinal immobilization on consolidation of posterolateral lumbosacral fusion. A roentgen stereophotogrammetric and radiographic analysis.

To determine the influence of the duration of postoperative lumbar immobilization with the aid of a rigid lumbar orthosis on the consolidation of posterolateral lumbosacral fusions, 22 patients with no previous osseous spinal surgery and with fusion without osteosynthesis due to spondylolysis-olisthesis Grade 1 to 2 or intervertebral disc or facet joint disorder were examined by roentgen stereophotogrammetric analysis in supine and erect positions and by conventional radiography for 1 year after surgery. In Series 1, patients (n = 11) were instructed to keep the trunk straight with the aid of a molded, rigid lumbar orthosis for 5 months after surgery; and in Series 2 (n = 11), the same instructions were given, but for 3 months. In Series 1, osseous fusion was seen on radiographs in eight patients. In these patients, the intervertebral translations between the fused vertebrae began to decrease 3-6 months after surgery, and within 1 year, the fusions became rigid, as defined by roentgen stereophotogrammetric analysis, or intervertebral translations of mostly less than 1 mm persisted. In three patients with poor fusion still seen on radiographs 1 year after surgery, no rigid fusion was obtained and intervertebral translations of up to 10 mm persisted. In Series 2, a similar roentgen stereophotogrammetric analysis pattern was noted in two patients with osseous fusion and in seven with poor fusion seen on radiographs. The fusion was radiographically doubtful in two patients. In these patients, the intervertebral translations decreased, but translations of 1.5 mm persisted 1 year after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Tendon excursion and dehiscence during early controlled mobilization after flexor tendon repair in zone II: an x-ray stereophotogrammetric analysis.

The effect of different methods on early controlled mobilization of the flexor profundus tendon regarding tendon excursion and dehiscence was examined during treatment of 20 tendons in 18 patients. An application of radiographic stereophotogrammetric analysis on movements of tendon tissue was developed and the tendons studied during the early postoperative period. Considerable differences of tendon excursion were found between the various mobilization methods and were dependent on the level of injury within zone II. The use of a mobilization method that includes a component of controlled active flexion is suggested for injuries at the A3 and A4 levels. This radiographic stereophotogrammetric analysis method developed for tendon excursion and dehiscence is new and provides knowledge that cannot be obtained in any other way.

Adolescent↗
PubMed1991

Roentgen stereophotogrammetric short-term analysis of growth rate in children operated for Crohn's disease.

Roentgen stereophotogrammetry is a new method for short term analysis of growth rate. Growth is measured over the growth zone in the distal fibula and is a fraction of the total statural growth. Normal growth rate in the distal fibula is about 15 micrograms/day at a total growth rate of 5 cm/year. The method was used to follow growth six months before and six months after surgery in six growth retarded children with Crohn's disease. Growth rate increased significantly (p less than 0.01) within three months after surgery from 5.8 microns/day before operation to 15.8 microns/day three months after operation and six months postoperatively had reached 18.0 micron/day. Improved growth could be recorded as early as four weeks after operation. The Roentgen stereophotogrammetric analysis (RSA) gives a unique possibility to follow short-term changes in growth rate in children with disturbed growth and to use growth rate as a quick assessment of response.

Adolescent↗
PubMed1991

In vivo measurements of relative motion between an uncemented femoral total hip component and the femur by roentgen stereophotogrammetric analysis.

Roentgen stereophotogrammetric analysis (RSA) was used to study rotation and subsidence of an uncemented polyethylene-coated femoral component for total hip arthroplasty in ten patients younger than 55 years of age. Three years postoperatively, the total subsidence averaged 2.44 mm and the internal rotation was 7.4 degrees. The rate of subsidence decreased between the observation periods, whereas the rate of rotation, after an initial significant decrease, became almost constant. One patient, who was a clinical failure and required revision arthroplasty, had a significantly higher rate of migration after six months. The pattern of subsidence in the absence of pain might be the normal reaction of bone to an uncemented prosthesis, but the continuing rotation suggests the potential for failure of the arthroplasty. The type of analysis made possible in RSA may allow early prediction of the success of arthroplasties and significantly speed the design cycle for arthroplasty components.

Adult↗
PubMed1990

Variability of measurements of cranial growth in the rabbit.

This study concerns techniques used in experimental cranial growth research: roentgen cephalometry, roentgen stereophotogrammetry, and gross measurements (osteometry). A comparison of the precision of these methods has not been found in the literature. Computation of technical errors is fundamental to the sound evaluation of registered findings, and such a presentation must be obligatory in all biometric reports. We compared the measurement error of roentgen cephalometric and osteometric data with that obtained by roentgen stereophotogrammetry (RSA). RSA demonstrates a superior replicability, and this technique gives possibilities for kinematic and volumetric determinations simultaneously with distance evaluation. Roentgen cephalometry has the advantage of enabling distance and angular measurements between any well-defined skeletal points or lines. This technique, preferably after implantation of bone markers, is a reliable alternative, but optimal results necessitates calculations of the magnification factor for each bone segment involved. Direct osteometry does not contribute additional information, but problems of image magnification are omitted. Preferably, one individual should perform all measurements regardless of the method used. Growth rates and values calculated by one technique cannot be directly transformed to some other approach. In all probability, assessments of distance changes would gain substantially by using one technical approach consistently throughout actual age intervals. The least variable measurements of sutural growth are made for sutures growing primarily in one plane and with substantial growth rates. One must realize that differences among studies may be due to the limitations of, in particular, the cephalometric and osteometric techniques.

Animals↗
PubMed1990

Mobility of the lower lumbar spine after posterolateral fusion determined by roentgen stereophotogrammetric analysis.

To determine the time-table for intervertebral stabilization after posterolateral fusion without osteosynthesis in the lower lumbar spine, 11 patients with no previous spinal surgery and with fusion due to spondylolysisolisthesis Grade 1 to 2 or lumbar disc disorder/facet joint arthrosis were examined by roentgen stereophotogrammetric analysis (RSA) in supine and erect positions, and by conventional radiography for 1 year after surgery. In eight patients with osseous fusion radiographically, the sagittal and the vertical translations between the fused vertebral segments began to decrease after 3 to 6 months. However, the time for rigid fusion as defined by RSA varied between 3 months and 1 year, and in four patients sagittal/vertical translations of mostly less than 1 mm still persisted at 1 year postoperatively. In three patients with poor fusion radiographically, no rigid fusion as defined by RSA was obtained. Sagittal/vertical translations of 1 to 10 mm persisted at 1 year postoperatively in these patients. The preoperative pain disappeared in all patients except in one who had osseous fusion radiographically but persisting translations after 1 year.

Adult↗
PubMed1990

Fibular mobility in chronic lateral instability of the ankle.

Using roentgen stereophotogrammetric analysis we recorded the mobility of the lateral malleolus under maximum passive plantarflexion and dorsiflexion and during the anterior drawer and the adduction tests in 29 patients with chronic lateral instability of the ankle. Medial and anterior displacements were observed during plantarflexion, at the adduction test and at the posterior loading of the tibia. At dorsiflexion we recorded posterior fibular shifts. The simultaneously occurring fibular rotations were small. Chronic lateral instability of the ankle was associated with slightly increased fibular movements during plantarflexion and dorsiflexion, and at the adduction test in some patients with bilateral symptoms, perhaps reflecting a generalized joint laxity.

Adolescent↗
PubMed1990

The effect of a stem on the tibial component of knee arthroplasty. A roentgen stereophotogrammetric study of uncemented tibial components in the Freeman-Samuelson knee arthroplasty.

We studied the effect of a metal tray with an intramedullary stem on the micromotion of the tibial component in total knee arthroplasty. Of 32 uncemented Freeman-Samuelson knee arthroplasties performed in London and Gothenburg, nine had a metal backing and stem added to the tibial component. Micromotion of the tibial components, expressed as migration and inducible displacement, was analysed using roentgen stereophotogrammetric analysis up to two years follow-up. The addition of a metal back and a 110 mm stem to the standard polyethylene component significantly reduced both migration over two years and inducible displacement.

Adult↗
PubMed1990

Cold flow reduced by metal backing. An in vivo roentgen stereophotogrammetric analysis of unicompartmental tibial components.

Thirty-six cases of unicompartmental arthroplasty for gonarthrosis were followed for 6 years. The arthroplasties were prepared for roentgen stereophotogrammetric analysis (RSA) by marking the tibial components and the tibial methaphysis with tantalum balls. Nineteen out of 24 cases with a polyethylene tibial component had an increase in intermarker distances signifying progressive enlargement of the prosthesis due to cold flow. The enlargement was up to 2.8 percent of the circumference and was greater for 9 mm than for 12 mm thick components. Twelve cases with a metal-backed tibial component showed no cold flow. No correlation between cold flow and demographic, clinical, or radiographic data was found.

Aged↗
PubMed1990

Early detection of prosthetic-hip loosening. Comparison of low- and high-viscosity bone cement.

In 1987, we reported the 1-year migration of the prosthetic components in 16 hips followed by roentgen stereophotogrammetry after fixation with either low- or high-viscosity cement. We now report the migration of these prosthetic components during another 2 postoperative years. Eight acetabular components, four in each group, migrated cranially; and four femoral components, three in the low-viscosity and one in the high-viscosity group, migrated distally. All but two migrations were obvious 4 months postoperatively, which indicates that what is called late loosening is the result of late detection rather than of late occurrence of loosening. Low-viscosity cement did not provide improved prosthetic fixation.

Bone Cements↗
PubMed1990

Roentgen stereophotogrammetric analysis.

Soon after Roentgen's discovery, the 'new' rays were used to produce stereoscopic images or used for spatial reconstruction of positions of foreign bodies. However, no systematic use of roentgen stereo measurements seems to have occurred until the 1970's, although many attempts have been made before. Since 1972, a system for roentgen stereophotogrammetry has been in use at the University Hospital in Lund. The system has been named RSA, roentgen stereophotogrammetric analysis. It is a complete system, including instrumentation for implanting tantalum landmarks, devices for calibration of the stereo roentgen set-up, and comprehensive software. Using different calibration set-ups, any part of the body can be investigated under different conditions using standard roentgen equipment. The computer programs make it possible to calculate spatial landmark coordinates from measured film coordinates, and further to calculate growth, and volume changes or kinematic variables in well-defined and generally used terms. After the basic principles have been established, a survey of applications grouped according to anatomic regions follows. Special emphasis is laid on total hip and knee replacement, which besides complex craniofacial and spinal disorders, are the most rewarding fields of study.

Photogrammetry↗
PubMed1990

Porous coated anatomic tricompartmental tibial components. The relationship between prosthetic position and micromotion.

Micromotion of the tibial component, both as migration over time and as inducible displacement in response to external physiologic forces, was studied in 20 cases of gonarthrosis. The patients had Porous Coated Anatomic primary total knee arthroplasty and were followed for four years. All cases but one were clinically successful. Thirteen components were inserted without cement, while in seven, high-viscosity Palacos cement was used. Full postoperative weight bearing was allowed in all cases. During the first year, noncemented components migrated a mean of 2.6 mm, while cemented components migrated a mean of 1.1 mm. About 1 mm of migration of noncemented components was in the downward direction, i.e., subsidence occurred, mostly during the first year. After one year, the noncemented components had stabilized more than the cemented ones. There was a significant correlation between the migration after one year and the postoperative prosthetic position and alignment of the leg. A mean maximum inducible displacement (the total vector displacement of the prosthetic marker that moved the most) of 0.7 mm and 0.4 mm was found for noncemented and cemented components, respectively. The micromotion found was of the same magnitude as that for other cemented and noncemented prosthetic systems previously reported.

Aged↗
PubMed1989

Movements of the sacroiliac joints. A roentgen stereophotogrammetric analysis.

Twenty-five patients (21 females and 4 males) with sacroiliac joint disorders were studied with roentgen stereophotogrammetry in physiologic positions as well as in the extreme of physiologic positions. There was a constant pattern of motion with different load, especially around the transverse axis. The rotations were small and in mean between position 2.5 degrees (0.8 degree-3.9 degrees). The translation was, mean, 0.7 mm (0.1-1.6 mm). There was no difference between symptomatic and asymptomatic joints.

Humans↗