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Biomedical subjects

G Selvik

Publications and source records attributed to G Selvik.

At least 37 records · Page 2Linked to original sources
PubMed1989

Kinematics of the ankle/foot complex: plantarflexion and dorsiflexion.

In an in vivo investigation of eight healthy volunteers, three dimensional ankle/foot kinematics were analyzed by roentgen stereophotogrammetry in 10 degrees steps of motion from 30 degrees of plantar flexion to 30 degrees of dorsiflexion of the foot. The study included all of the joints between the tibia and the first metatarsal, as well as the talocalcaneal joint, and was performed under full body load. Although the talocrural joint was found to account for most of the rotation around the transverse axis occurring from 30 degrees of plantar flexion to 30 degrees of dorsiflexion, there was a substantial contribution from the joints of the arch. This was seen particularly in the input arc from 30 degrees of plantar flexion to the neutral position, where the dorsiflexion motion of these joints amounted to 10% to 41% of the total transverse axis rotation.

Adult↗
PubMed1989

Kinematics of the ankle/foot complex--Part 2: Pronation and supination.

The influence of pronation and supination of the foot on the joints of the ankle/foot complex was analyzed three dimensionally by roetgen stereophotogrammetry in eight healthy volunteers. Radiopaque markers were introduced into the tibia, talus, calcaneus, navicular, medial cuneiform, and first metatarsal bones. The subjects stood on a platform that was tilted in 10 degree-steps from 20 degrees of pronation to 20 degrees of supination. Pairs of x-ray exposure were made in each position. Calculation of resulting joint deviations from the neutral position showed that the largest amounts of motion occurred in the talonavicular joint followed by the talocalcaneal joint, in the latter case mainly in supination. The joints proximal and distal to the medial cunriform also participated substantially in the total motion registered. The tibia showed an average of 0.2 degrees of external rotation for each degree of supination of the foot.

Ankle Joint↗
PubMed1989

Kinematics of the ankle/foot complex--Part 3: Influence of leg rotation.

In an in vivo kinematical investigation, the movements of the ankle/food complex induced by external rotation of the leg from an internally rotated position were analyzed by roentgen stereophotogrammetry. Radiopaque markers were introduced into the tibia, talus, calcaneus, navicular, medial cuneiform, and first metatarsal bones of eight healthy volunteers. Rotations occurring between these bones after 10 degrees increments of leg rotation were calculated in three dimensions. Movement of the leg from an internally rotated position to the neutral was found to induce motion mainly as internal rotation of the talus in relation to the tibia. Further external rotation induced motion mainly in the talonavicular and talocalcaneal joints, whereas a smaller amount of motion was seen in the joint between the navicular and the medial cuneiform.

Ankle Joint↗
PubMed1989

The axis of rotation of the ankle joint.

The axis of the talo-crural joint was analysed by roentgen stereophotogrammetry in eight healthy volunteers. Examinations were performed at 10 degrees increments of flexion and pronation/supination of the foot as well as medial and lateral rotation of the leg. Results indicate that the talo-crural joint axis changes continuously throughout the range of movement. In dorsiflexion it tended to be oblique downward and laterally. In rotation of the leg, the axis took varying inclinations between horizontal and vertical. All axes in each subject lay close to the midpoint of a line between the tips of the malleoli. Our study indicates that the talo-crural joint axis may alter considerably during the arc of motion and differ significantly between individuals. This prompts caution in the use of hinge axes in orthoses and prostheses for the ankle.

Adult↗
PubMed1989

Micromotion of the total knee.

Eight patients with gonarthrosis were operated on with a noncemented all-polyethylene ICLH endoprosthesis. Radiographic examination up to 2 years postoperatively included roentgen stereophotogrammetric analysis (RSA), which demonstrated micromotion of all the implants. However, the mean subsidence was only 0.4 mm for both the tibial and the femoral components.

Aged↗
PubMed1989

Stapling for tibial-growth deformity. A case report on roentgen stereophotogrammetric analysis.

A 9-year-old boy sustained a Salter-Harris Type IV fracture in the proximal tibia. The injury resulted in a progressive valgus deformity, detected already after 3 months by roentgen stereophotogrammetry. After temporary stapling medially, the growth rate increased laterally and the deformity was corrected. Unilateral stapling is an alternative procedure for correcting angular deformity following a physeal injury.

Child↗
PubMed1989

Chronic lateral instability of the ankle. Roentgen stereophotogrammetry of talar position.

Using roentgen stereophotogrammetric analysis (RSA), we investigated the talar mobility in 54 ankles during the anterior drawer and adduction tests. Talar tilt was increased in ankles with unilateral symptoms of chronic lateral instability. No other difference in talar tilt and anterior drawer sign was noted comparing ankles with and without symptoms. We conclude that mechanical tests cannot always verify the diagnosis "chronic lateral instability of the ankle".

Adolescent↗
PubMed1989

Ankle fractures. A clinical and roentgenographic stereophotogrammetric study.

To analyze postoperative fracture stability and late ankle mortise mobility, 46 lateral malleolar and 53 bimalleolar ankle fractures were randomly separated to either early or late weight-bearing groups and followed for 18 months. Internal fixation with cerclage wires, staples, and pins were used. Better clinical results were found among the lateral malleolar compared with the bimalleolar fractures. Roentgenographic stereophotogrammetric analysis revealed only small movements in the ankle mortise during fracture healing, although a greater dorsal translation and outward rotation of the fibula were found among the pronation injuries compared with the supination injuries. The repair of a ruptured deltoid ligament was not necessary. An increased rigidity of the ankle mortise was found 18 months after injury. Internal fixation with cerclage wires, staples, and pins is a simple and reliable method that provides sufficient stability to allow immediate postoperative weight bearing in a walking cast for most ankle fractures.

Adolescent↗
PubMed1989

Roentgen stereophotogrammetry. A method for the study of the kinematics of the skeletal system.

I have developed a roentgen stereophotogrammetric method for determination of positions of radiopaque markers in an object. The space coordinates are determined in a laboratory coordinate system, which is defined by markers in a test "cage". The markers in the test cage function as calibration points, and are roentgenographed on the same film(s) as the object. Calibration markers and object markers are exposed from two roentgen foci. The cage markers, are in their function, of two kinds, of which one (fiducial marks) is used for projective transformations of the image points to the laboratory coordinate system, while the other (control points) is used for determining the roentgen foci positions in the same coordinate system. After these calculations have been performed, the three-dimensional coordinates of object indicators are determined by crossing of lines between the roentgen foci and the transformed image points. The mathematical principles for the reconstruction of the bundles of rays from the roentgen foci at the moment of exposure are discussed in Chapter 2. Three constructions of test cages, Models 1A and 1B, and Model 2 are also discussed there. In Test Cage Model 1, the two exposures of the object are obtained on one film, but in Model 2 we expose on two films that are perpendicular to each other. The three cage models are, in turn, intended for high-accuracy determinations of lengths (Model 1A), general determinations of space coordinates, especially in larger objects (Model 1B), and high-accuracy determinations of space coordinates in medium-sized objects (Model 1B), and high-accuracy determinations of space coordinates in medium-sized objects (Model 1B). Note, that if the positions of the roentgen foci and the film are not altered, we can roentgenograph the calibration points separately on a film, and then, after removal of the test cage, roentgenograph the object on the same film. The calibration of the test cages is discussed in Chapter 3. To determine coordinates of markers in a plane is easy, if a rectangular coordinatograph is accessible, and we use the same instrument as for the measurements of the films, a Wild Autograph A8. Determination of the position in space of the plate with control points in relation to the plate with fiducial marks requires more consideration. We describe how the degrees of freedom of the plate with control points (translations in x- and y-directions, rotation angle phi about a z-axis), which are difficult to control at construction of the test cages, can be determined by specific calibration procedures.(ABSTRACT TRUNCATED AT 400 WORDS)

Biomechanical Phenomena↗
PubMed1988

Changes in mandibular position during treatment with disk-repositioning onlays: a roentgen stereophotogrammetric study.

Seven patients with temporomandibular joint disk displacement were treated with disk-repositioning onlays, and changes in the mandibular position were studied by means of roentgen stereophotogrammetry. A wide range of changes in mandibular position was seen at cementation of the onlays and during the observation period. On an average, recapturing of the disk and cementation of the onlays lowered the mandible by 2.5 mm and protruded it by 0.5 mm. During the observation period of 7 months the mandible had a tendency to resume its original position. The relapse was 80% in the sagittal plane, 70% in the transverse plane, and 12% in the vertical plane. It was concluded that disk-repositioning onlays can be used to lower the mandible with a relatively small relapse. Changes in the horizontal plane, however, seem to be less stable.

Adolescent↗
PubMed1988

Accuracy of the oblique lateral transcranial projection, lateral tomography, and x-ray stereometry in evaluation of mandibular condyle displacement.

Condylar displacement similar to that occurring during and after mandibular ramus osteotomies was simulated in an in vitro study. Three different radiographic methods were used to measure the displacement, and the accuracy of the methods was compared. The stereometric method was more accurate than the plain radiographic methods and permitted measurements in all three dimensions. The oblique lateral transcranial projection was more accurate than lateral tomography, possibly because identification of measurement points in lateral tomography was complicated by the substantial displacement of the condyle.

Craniotomy↗
PubMed1988

Condylar displacement after oblique sliding osteotomy of the mandibular rami. A stereometric and plain radiographic study.

Condylar displacement after oblique sliding osteotomy was examined in 8 patients by X-ray stereometry and plain radiography. During the first 8 postoperative weeks the displacement was in a medial/superior/posterior direction. After removal of the intermaxillary fixation a continuous lateral translation was found together with an initial inferior and a minor anterior translation which after 6 months postoperatively changed to a posterior translation. At 12 months postoperatively a difference in findings of condylar position was found between the X-ray stereometric and plain radiographic analyses. We regard this difference as due to the sum of remodelling and method errors.

Adult↗
PubMed1988

Active knee motion after cruciate ligament rupture. Stereoradiography.

In 10 patients with an old injury of the anterior cruciate ligament, the three-dimensional movements of the knee joint were studied when the patients flexed their knees. Tibial motions were recorded using roentgen stereophotogrammetric analysis. Internal rotation and adduction of the tibia were reduced in the injured knees when compared with the intact knees; during flexion of the knee joint, the tibial intercondylar eminence occupied a more lateral and posterior position on the injured side. Our results may indicate that the knee joint is continuously exposed to abnormal stresses when the anterior cruciate ligament is torn.

Adult↗
PubMed1988

Growth in rabbits during alternate-day cortisone injections: near normal growth on days without cortisone.

Longitudinal bone growth in rabbits during treatment with hydrocortisone was measured by means of Roentgen Stereophotogrammetric Analysis, RSA. This method allows accurate measurement of the distance between metallic markers inserted into long bones. Hydrocortisone was given in i.m. injections as single doses and as repeated doses, daily or every other day. Single injections of hydrocortisone resulted in three types of growth effect, depending on dosage. Low dosage (less than 4 mg/kg b.w.) produced no blunting of growth. Intermediate dosage (4-32 mg/kg b.w.) retarded growth during the first but not the second day after the injection. The effect of high dosage (64-128 mg/kg b.w.) lasted for two days. During daily treatment (4 and 16 mg/kg b.w.), growth decreased to a constant level. During alternate-day steroid injections with a double dose every other day, growth almost normalized during the steroid-free days. Average growth was significantly greater during alternate-day injections than during daily injections. It is concluded that alternate-day treatment has no unfavorable effect on growth so long as the interval between injections exceeds the duration of the growth effect of each single dose.

Animals↗
PubMed1988

Three-dimensional instability of the anterior cruciate deficient knee.

Using roentgen stereophotogrammetry we have recorded the three-dimensional movements of the knee during an anteroposterior laxity test in 36 patients with torn anterior cruciate ligaments and in three cadaver knees. At 30 degrees of knee flexion and before loads were applied the tibia occupied a more laterally rotated position if the anterior cruciate ligament had been injured. When the tibia was pulled anteriorly knees with cruciate deficiency rotated more laterally and were more abducted than normal knees. Posterior traction induced lateral rotation in the injured knee and medial rotation in the intact one. Precise knowledge of the three-dimensional instability of the anterior cruciate deficient knee may be important when the laxity is evaluated only in relation to one of the three cardinal axes.

Adult↗
PubMed1988

Mobilization after operation of ankle fractures. Good results of early motion and weight bearing.

Fifty-one patients with dislocated lateral malleolar fractures took part in this prospective randomized study. Active ankle movements with weight bearing in an orthosis were compared with active ankle movements without weight bearing using a dorsal splint. By using cerclage, staples, and pins (Cedell 1967), an exact reconstruction of the ankle mortise was achieved in 44/51 ankles. Radiographic and stereophotogrammetric analyses at 3 months showed no redislocation and only small movements in the ankle mortise. Better loaded dorsal flexion capacity at 3 months was found in the orthosis group. This study was designed as the second part of a consecutive study. In the first part, early or late weight bearing without ankle exercises was compared (Ahl et al. 1986). The results from the two consecutive parts indicate that active ankle movements in combination with weight bearing facilitate and improve the rehabilitation following operation for an ankle fracture.

Adult↗