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PubMed1987

Cranial suture growth as correlated with weight gain in rabbits.

The association of skull growth to weight gain is essential in biometric investigations for correct interpretation of registered results. This was studied in 16 male New Zealand white rabbits aged between 32 and 143 days using roentgen stereophotogrammetric analysis for measurements of cranial suture growth increments and an accurate scale for weight controls. Skull growth decreased continuously with time apart from the first interval; weight changes varied. Calculated coefficients of determination, linear regressions, and the correlation coefficients for each age interval demonstrated weak correlations. No significant difference between the facial and neurocranial skeleton relative to weight was discerned. The low dependence of cranial variables on weight, as well as the fluctuating weight development, imply a need of great wariness in assessing health conditions by weight registration solely.

Animals↗
PubMed1988

Principal component analysis of intercusp distances on the lower first molars of three human populations.

The distances between the five main cusps of lower first molars were measured on moiré photographs of casts obtained from Japanese, Dutch and Australian Aboriginal children. Principal component analysis of the intercusp distances, log transformed and standardized so that average tooth size was held constant, revealed three sources of shape variation in cusp topography. All populations were similar for scores on component 1 which was concerned with variations in the position of the hypoconulid. The Dutch had lowest scores on component 2 indicating small buccolingual distances compared with mesiodistal, whereas the Australian Aboriginals had the lowest mean score on component 3, expressing the distances between metaconid, entoconid and hypoconulid.

Asian People↗
PubMed1980

An investigation into some of the factors concerned in the surgical removal of the impacted lower wisdom tooth, including a double blind trial of chymoral.

During the surgical extraction of 102 impacted lower wisdom teeth the following factors were studied: the amount of trauma applied during tooth removal; the duration of the operation; post-operative swelling; post-operative trismus; sex differences; the relationship between swelling and trismus; the pattern of development and subsidence of swelling and trismus. This study was combined with a clinical 'double-blind' trial of the drug Chymoral.

Chymotrypsin↗
PubMed1994

Congenital breast asymmetry: subjective and objective assessment.

There is currently no standard objective method for the assessment of developmental breast asymmetry. The results of corrective surgery in 24 patients with congenital breast deformities were evaluated subjectively (symmetry scores by patients and panels of observers), and objectively (linear measurements of nipple position and stereophotogrammetrically determined breast volumes). The latter were obtained using a newly developed prototype computer based technique (Bodymap). This study is the first reported use of stereophotogrammetry in assessing results of surgery for the correction of congenital breast asymmetry. The results obtained, their clinical implications, and the usefulness of Bodymap in the objective measurement of breast asymmetry are discussed.

Adolescent↗
PubMed1979

Evaluation of Cartesian coordinates and radiation doses in points determined with stereo x-ray techniques.

A Fortran computer program STEV (stereo evaluation) is described. The principles of the stereo techniques together with the calculation method of the stereo coordinates are given briefly. The determination of the rectangular coordinates from mean stereo coordinates is described. Radiation doses in anatomical points, during intracavitary and interstitial radiation therapy, are calculated, taking into account a statistical evaluation of the measurement errors.

Computers↗
PubMed1996

Optimization and smoothing techniques in movement analysis.

This paper deals with accurate estimation of the degrees of freedom (DOF) of a body segment, starting from the trajectories of clusters of markers acquired with a suitable measurement system. The most commonly employed estimation procedures involve two sequential steps, a trajectory smoothing algorithm and a DOF reconstruction routine. Three optimized smoothing and reconstruction schemes are described, analyzed and tested and their performances are compared with each other and with those of a more traditional technique which contains no optimization criteria. All three schemes include an iterative, weighted-least-squares DOF reconstruction routine and a self-tuning, zero-phase-shift, 4th-order Butterworth filter. Both routines are extensively described and validated on the basis of numerically-simulated marker trajectories. Test results, analyzed on a statistical basis, show that the use of an optimization routine provides a visible improvement in DOF reconstruction. This performance has also been confirmed using stereophotogrammetric data collected on a subject wearing an external fracture fixation device which provides reference values for the bone DOF. Angular DOF estimated applying the optimized method to skin technical clusters are much closer to the reference values than the non-optimized values. Smoothing of data further improves the reconstruction accuracy while a far less crucial role is played by the order in which smoothing and reconstruction routines are applied.

Algorithms↗
PubMed1982

Three-dimensional cinematography with control object of unknown shape.

A technique for reconstruction of three-dimensional (3D) motion which involves a simple filming procedure but allows the deduction of coordinates in large object volumes was developed. Internal camera parameters are calculated from measurements of the film images of two calibrated crosses while external camera parameters are calculated from the film images of points in a control object of unknown shape but at least one known length. The control object, which includes the volume in which the activity is to take place, is formed by a series of poles placed at unknown locations, each carrying two targets. From the internal and external camera parameters, and from locations of the images of point in the films of the two cameras, 3D coordinates of the point can be calculated. Root mean square errors of the three coordinates of points in a large object volume (5m x 5m x 1.5m) were 15 mm, 13 mm, 13 mm and 6 mm, and relative errors in lengths averaged 0.5%, 0.7% and 0.5%, respectively.

Mathematics↗
PubMed1982

Analysis of human back shape using surface curvatures.

A method for the evaluation of surface measurements of the human back is presented. A shape analysis is carried out in terms of surface curvature. This is calculated using differential geometry of surfaces. Similar to other invariant shape parameters, the surface curvature does not depend on a coordinate system and is thus independent of the patient's position. The advantages of such an invariant shape analysis are discussed and first results are presented.

Back↗
PubMed1983

A close-range photogrammetric system for 3-D measurements and perspective diagramming in biomechanics.

Criteria considered in developing a close-range photogrammetric three-dimensional mapping system and its overall performance are discussed. The system consists of a stereophotographic capability of two cameras with synchronized shutters, a stereoplotting instrument with three-dimensional digitizing capability and a Calcomp plotter. Mapping of human knee-bones (femur and tibia) and perspective diagramming for various attitudes of one bone head with regard to the other are illustrated. The system works off-line with respect to the three principal components. The system is fully operational and is considered very efficient with regard to the current needs. Various possibilities are discussed.

Biomechanical Phenomena↗
PubMed1984

Detection of stimulated back muscle contractions by moiré topography.

The ability to treat scoliosis via surface stimulated trunk muscle contractions is now being evaluated at several treatment centers. In order to make biomechanical analysis of the procedure, so that the technique can be used optimally, data are needed to quantify the muscle contractions and structural changes by different electrode locations. This paper presents the use of a modified shadow moiré technique to quantify geometric changes resulting from electrical stimulation applied to the surface of the back in a healthy subject.

Back↗
PubMed1985

Analytical stereophotogrammetric determination of three-dimensional knee-joint geometry.

An analytical stereophotogrammetric method is introduced to measure the three-dimensional geometry of articular surfaces in vitro. Information of this kind is particularly useful for mathematical joint models and anthropological studies. The method requires no specific equipment, such as a stereocomparator, contrarily to other techniques reported (e.g. Ghosh, 1983) and is relatively simple and inexpensive. The background of the method is outlined in the present paper, and results of accuracy and precision tests are presented. It is shown that an accuracy on the order of 0.2 mm (95% confidence interval) is well feasible in actual knee-joint evaluations, if the measuring procedure is conducted carefully. The method is illustrated by measuring and comparing the articular surface geometries of a bilateral pair of knee joints.

Biomechanical Phenomena↗
PubMed1985

Measurement of surface deformation of soft tissue.

A method is described for measuring the surface shape and deformations of soft tissue in three dimensions. The method uses close range stereophotogrammetry to record the three-dimensional locations of miniature optical targets applied to the tissue surface. This has been applied to study of human lumbar intervertebral disc. Measurements of the strain along surface annular fibers have been made under varying loads. In this case the maximum expected errors are about 0.15 mm, which corresponds to a strain of less than 1%. Preliminary findings have differed from predictions made in published mathematical models for the disc in that they show very little strain of the annulus in compression loading, but confirm axial torsional loading as liable to produce mechanical disruption of the disc annulus.

Animals↗
PubMed1985

Moiré patterns: an accurate technique for determination of the locus of the centres of rotation.

This study describes an accurate technique for the determination of the centre of rotation of small angles. The moiré fringe method localizes the centre of rotation by defining two primary fringes, each of which is found by the intersection of three lines. The primary fringes intersect at the centre of rotation at 90 degrees to each other, the angle least likely to produce an error in measurement. By utilizing joints with known centres of rotation, we have found that the method is extremely accurate and reproducible to within 2 mm of the real centre for angular changes as small as 3 degrees. This technique is useful in evaluating whether a joint is a simple hinge, i.e. rotating about a single axis of rotation or whether the joint moves about a changing axis of rotation referred to as a locus or centrode.

Arthrography↗