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At least 163 records · Page 9Linked to original sources
PubMed2002

[Kinematic changes after bicondylar resurfacing knee arthroplasty].

AIM: Knee joint motion appears as a hinge movement around the flexion - extension axis. But corresponding to the rolling-sliding-mechanism and alternative models of knee joint kinematics an instant center pathway must be expected. Objective of the study was the comparison of this pathway when assessed in the sagittal plane in patients with preoperative varus or valgus deformity. METHOD: A total of 40 patients either with varus or valgus deformity (20 in each group) were examined before and 6 months after implantation of PFC(R)-SIGMA prostheses. Apart from the influence of knee joint deformity (35 degrees varus to 24 degrees valgus), a so called soft tissue ratio was investigated. Therefore the relation of thigh and femur as well as lower limb and tibia diameters was calculated and combined in one value. The examination by means of photogrammetry consisted of a standardized chair with passive knee joint movement (90 degrees to 0 degrees flexion) supported by an electric motor. The position of defined skin markers was assessed by digital camara with online transmission to PC. The instant center pathway was then evaluated applying the Reuleaux-technique based on the changes of skin marker positions. RESULTS: Results showed a dependence of the course and dimension of the instant center pathway on the extent of soft tissue ratio as well as knee joint deformity. Small values of the ratio (W = 2.9) were represented by round or oval courses of the pathway whereas increasing ratios (W = 4.0) led to triangular and slightly increased dimensions of the courses. Varus deformitywas primarily combined with an increase of the pathways dimension and in contrast, valgus deformity showed decreased pathways. In each case, dimension normalized after prostheses implantation. CONCLUSION: The instant center pathway of knee joint motion showed for both patient groups characteristic phenomen. They were clearly combined with constitutional and clinical features of each patient.

Aged↗
PubMedDate not supplied

[Late results of the surgical correction of funnel chest. Evaluation with subjective and objective criteria including moiré topography].

The long term results of 32 patients with funnel chest deformity that were operatively treated by means of Rehbein's metal implants have been reviewed. The investigated criteria were electrocardiography, pulmonary function, radiographical measurements, and photogrammetry of the frontal thoracic plane (Moiré-Topography). There was no significant change of the electrocardiography and pulmonary function due to the operative treatment. Roentgenometric and surface measurement data showed in 40% of the cases investigated minor up to complete relapses. According to the results the indications for operative treatment and the importance of the patient's age at this time are discussed.

Adolescent↗
PubMed1999

Soft-tissue facial morphometry from 6 years to adulthood: a three-dimensional growth study using a new modeling.

A recently introduced three-dimensional computerized system with landmark representation of the soft-tissue facial surface allows noninvasive and fast quantitative study of facial growth. The aims of the present investigation were (1) to quantify growth changes in soft-tissue facial morphology, (2) to evaluate sex differences in growth patterns, and (3) to provide reference data for selected angular and linear measurements that could be of interest for the objective analysis of maxillofacial surgery or orthodontic patients. The three-dimensional coordinates of 22 standardized facial landmarks were automatically collected by automated infrared photogrammetry using the three-dimensional facial morphometry method in a mixed longitudinal and cross-sectional study, in which 2023 examinations were obtained in 1348 healthy nonpatient subjects between 6 years of age and young adulthood. Selected parameters (angles, linear distances, and ratios) were calculated and averaged for age and sex. Male values were compared with female values by means of Student's t test. Within each age group, linear distances were significantly larger in boys than in girls (p < 0.05) with some exceptions coinciding with the earlier female growth spurt, whereas angular measurements did not show a corresponding sexual dimorphism. Linear distances in girls had almost reached adult dimensions in the 12-to-13-year-old age group, whereas in boys a large increase was still to occur. This was most evident in the middle third of the face, where both sexes showed almost the same dimension and amount of growth up to the age of 13, with significant differences afterward, boys being larger than girls. On the contrary, in the lower third of the face, significant differences occurred throughout the whole investigated period, boys being always larger than girls. The male versus female angular comparison reflected the differential timing in attainment of adult proportions. The three-dimensional facial morphometry method allowed the noninvasive evaluation of a large sample of nonpatient subjects, leading to the definition of three-dimensional normative data about facial soft tissues. The method could supplement more invasive radiographic evaluations, allowing frequent examinations of children and adolescents before and during treatment, as well as in the follow-up.

Adolescent↗
PubMed1994

Three-dimensional motion of the upper cervical spine in rheumatoid arthritis.

Rheumatoid arthritis frequently contributes to instability of the upper cervical spine. Rotational instability of the upper cervical spine was evaluated in rheumatoid arthritis patients using biplanar x-ray photogrammetry. Three-dimensional cervical motion and the instantaneous axis of rotation of the atlas relative to the axis were evaluated in normal and rheumatoid arthritis patients during axial rotation in the horizontal plane. Anterior atlantoaxial subluxation did not increase during axial head rotation in either the atlantoaxial subluxation or the vertical subluxation groups, while the instantaneous axes of rotation were distributed posteriorly in the dens in the RA-normal group, but were widely scattered in the atlantoaxial subluxation group.

Arthritis, Rheumatoid↗
PubMed2003

Assessment of the 3-d reconstruction and high-resolution geometrical modeling of the human skeletal trunk from 2-D radiographic images.

This paper presents an in vivo validation of a method for the three-dimensional (3-D) high-resolution modeling of the human spine, rib cage, and pelvis for the study of spinal deformities. The method uses an adaptation of a standard close-range photogrammetry method called direct linear transformation to reconstruct the 3-D coordinates of anatomical landmarks from three radiographic images of the subject's trunk. It then deforms in 3-D 1-mm-resolution anatomical primitives (reference bones) obtained by serial computed tomography-scan reconstruction of a dry specimen. The free-form deformation is calculated using dual kriging equations. In vivo validation of this method on 40 scoliotic vertebrae gives an overall accuracy of 3.3 +/- 3.8 mm, making it an adequate tool for clinical studies and mechanical analysis purposes.

Humans↗
PubMed1978

Calculation of surface area and volume of human erythrocytes from scanning electron micrographs.

This article demonstrates that surface and volume measurements of individual human erythrocytes with varying shapes can be obtained from scanning electron micrographic stereopairs using an approach based on established principles of photogrammetry. Instead of calculating the coordinates of several hundred points plotted for each cell, a procedure that proves tedious and time-consuming, we show that a reasonable approximation of cell surface and volume can be achieved from simple geometrical models constructed with a small number of carefully measured points and angles, using a stereocomparator. The values obtained for two normal erythrocytes and for two distorted red cells from a patient with congenital pyruvate kinase deficiency haemolytic anaemia are consistent with available information on the geometry of these cells. Because scanning electron microscopy requires extensive manipulation of the cells, the values obtained cannot be applied to fresh living material, but appear fairly accurate for the purpose of comparison between cells prepared in the same manner.

Anemia, Hemolytic, Congenital↗
PubMed2004

A three-dimensional kinematic analysis of tongue flicking in Python molurus.

The forked snake tongue is a muscular organ without hard skeletal support. A functional interpretation of the variable arrangement of the intrinsic muscles along the tongue requires a quantitative analysis of the motion performance during tongue protrusion and flicking. Therefore, high-speed fluoroscopy and high-speed stereo photogrammetry were used to analyse the three-dimensional shape changes of the tongue in Python molurus bivittatus (Boidae). The posterior protruding part of the tongue elongated up to 130% while the flicking anterior portion elongated maximally 60%. The differences in tongue strains relate to the absence or presence, respectively, of longitudinal muscle fibres in the peripheral tongue. Maximum overall protrusion velocity (4.3 m s(-1)) occurred initially when the tongue tip left the mouth. Maximum tongue length of approximately 0.01 body length (20 mm) was reached during the first tongue flick. These observations are discussed within the scope of the biomechanical constraints of hydrostatic tongue protrusion: a negative forward pressure gradient, longitudinal tongue compliance and axial tongue stiffness. The three-dimensional deformation varied along the tongue with a mean curvature of 0.06 mm(-1) and a maximum value of 0.5 mm(-1). At the basis of the anterior forked portion of the tongue tips, extreme curvatures up to 2.0 mm(-1) were observed. These quantitative results support previously proposed inferences about a hydrostatic elongation mechanism and may serve to evaluate future dynamic models of tongue flicking.

Animals↗
PubMed2000

Robotic-assisted internal fixation of hip fractures: a fluoroscopy-based intraoperative registration technique.

The internal fixation of proximal femoral (hip) fractures is the most frequently performed orthopaedic surgery procedure. When using a sliding compression hip screw, a commonly used fixation device, accurate positioning of the device within the femoral neck-head is achieved by initially drilling a pilot hole. A cannulated component of the hip screw is then inserted over the guide wire (surgical drill bit), which is used to drill the pilot hole. However, in practice, this fluoroscopically controlled drilling process is severely complicated by a depth perception problem and, as such, a surgeon can require several attempts to achieve a satisfactory guide wire placement. A prototype robotic-assisted orthopaedic surgery system has therefore been developed, with a view to achieving accurate right-first-time guide wire insertions. This paper describes the non-invasive digital X-ray photogrammetry-based registration technique which supports the proposed robotic-assisted drilling scenario. Results from preliminary laboratory (in vitro) trials employing this registration technique indicate that the cumulative error associated with the entire X-ray guided robotic system is within acceptable limits for the guide wire insertion process.

Fluoroscopy↗
PubMed1981

Photogrammetric registration of dental plaque accumulation in vivo.

Using the labial surface of upper anterior laterals for determination, the accumulation of plaque was assessed by means of a stereo-photogrammetric method. The stereoimages were subjected to photogrammetric evaluation, the part of the surface area covered by plaque being given in per cent of the total surface area of the tooth. Plaque extension and plaque topography was studied in young adults with healthy periodontia during a 20 day period of no oral hygiene. At the end of the experimental period, on an average 75 per cent of the surface area was covered by plaque, corresponding to an extension rate of 3.75 per cent per day. The correlation between plaque values obtained by photogrammetry and various estimates obtained from clinical scoring ranged between r = 0.66 and r = 0.78. It is concluded that the method introduced is a sensitive means of determining small amounts of plaque and should prove useful for in vivo investigation of plaque growth and plaque suppression, where measurements of high quality is of importance.

Adult↗
PubMed1999

Morphometric characteristics of toothless lower jaw ridge as a bed for total lower jaw prosthesis.

Analysis was made of 44 solid casts of toothless lower jaws. Stereophotogrammetry, a measurement procedure in photogrammetry, was used as a method in the measurement of solid casts. Adequate instruments and method of measurement made it possible to objectify anatomical and morphological structures of toothless lower jaws. The anterior width of the ridge in the region of canines was 22.70-35.50 mm. The posterior width in the first molars region was 43.30-59.10 mm, with statistically significant difference between the genders. The width at the level of posterior ridge of mandibular tubercle was 52.10-70.00 mm, with statistically significant difference between the genders. The length of the alveolar ridge between the symphysis and the tangent line of posterior ridge of mandibular tubercle in the medial line was 34.70-49.00 mm, without statistically significant difference between the genders. The surface of the toothless ridge is at the same time the surface of the total lower prosthesis bed. The size of the surface depended on the resorption and relation between the alveolar ridge and the surrounding active structures; it ranged between 103.21-205.50 mm2. The mean value being 145.99 mm2. The values obtained in our study are in approximate accordance with the reference literature data. They are the results of accurate measurements of solid casts.

Alveolar Process↗
PubMed1975

[Objective radiological stereophotogrammetry in dentistry].

By means of objective radiological stereo-photogrammetry of two extraoral stereoscopic radiograms, the location of dislocated impacted teeth was determined preoperatively in a model. During operation it was possible to find the teeth at the computed position.

Female↗
PubMed2000

[A hardware and software complex for producing 3D models of the teeth].

A complex of short-basis photogrammetry, methods and software for obtaining and analysis of 3D digital models of relief of dentition and its fragments is presented. This complex is intended for planning and evaluation of tooth preparation and quality of prosthetic treatment. The method was used to assess the correctness of dental shape repair by artificial crowns. The complex can form the base for the CAD/CAM technology.

Calibration↗
PubMedDate not supplied

[Equipment and technology for taking digital X-ray fluorographic films].

The paper deals with X-ray photogrammetry. It presents designs of different types of currently available digital X-ray fluographic apparatuses, their technical data and operating characteristics. Whether these apparatuses can be used for stereo X-ray photogrammetric survey is assessed.

Fluoroscopy↗
PubMed1975

Calibration and measurement in 3-dimensional monitoring of human motion by optoelectronic means. I. Preliminaries and theoretical aspects.

By combinding the obervations from a number of independent direction sensors, the spatial positions of one or more targets may be reconstructed. The theory of calibration and measurement in a computerized, interactive environment is discussed in the terminology of analytical photogrammetry, for applications in the field of biomechanics. The discussion is focussed upon optoelectronic system for movement monitoring in real-time rather than upon photography as is the conventional photogrammetric implementation.

Biomechanical Phenomena↗
PubMed2003

[Utility of three-dimensional soft tissue facial morphometry and conventional cephalometrics in people with normal occlusion].

OBJECTIVE: The purpose of this study was to compare the data of three-dimensional soft tissue obtained by using a three-dimensional digital photogrammetry and the two-dimensional data obtained by using a conventional cephalometry. METHODS: Three-dimensional characters of facial soft tissue were obtained by using four digital cameras. The authors developed necessary hardware and software systems and applied in stereophotogrammetry to obtain the data of three-dimensional facial soft tissues. A total of 40 people with normal occlusion, including 20 males and 20 females, were examined with both three-dimensional soft tissue facial morphometry and cephalometry. Three-dimensional soft tissue facial morphometry was performed, and their relations with facial cephalometry were analyzed. RESULTS: Significant correlations were found between 6 pairs of linear measurements, 4 pairs of angular measurements and 3 pairs of linear distant ratio measurements. The data obtained by three-dimensional facial soft tissue morphometry and two-dimensional cephalometry was identical. CONCLUSION: There was a correlation between the three-dimensional soft tissue facial morphometry and facial cephalometry. The data obtained by the three-dimensional soft tissue facial morphometry can partially represent facial hard tissue.

Adult↗
PubMed1989

Shadow photogrammetric apparatus for the quantitative evaluation of corneal buttons.

We have developed a technique for the accurate, quantitative, geometric evaluation of trephined and punched corneal buttons. A magnified shadow of the frontal and edge views of a corneal button mounted on the rotary stage of a modified optical comparator is projected onto the screen of the comparator and photographed. This process takes approximately three minutes. The diameters and edge profile at any meridian photographed can subsequently be analyzed from the film. The precision in measuring the diameters of well cut corneal buttons is +/- 23 microns, and in measuring the angle of the edge profile is +/- 1 degree. Statistical analysis of inter observer variability indicated excellent reproducibility of measurements. Shadow photogrammetry offers a standardized, accurate, and reproducible method for analysis of corneal trephination.

Calibration↗
PubMed1988

Spine and back-shape changes in scoliosis.

Thirty-five untreated patients with scoliosis were studied by Cobb radiography and back-surface photogrammetry on each of at least two clinic visits. Also, the maximum vertebral axial rotation was measured. Each pair of patient visits was classified as showing either a progression, improvement, or no change in the scoliosis using a threshold of 5 degrees change in the Cobb angle. The computer Cobb measurement was the most precise measurement, and the back-surface measurements were the least precise. The Cobb measurement of scoliosis is the most precise for detecting small changes, but can be improved by a computerized analysis of digitized radiographs.

Adolescent↗