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At least 595 records · Page 33Linked to original sources

PubMed2003

Facial asymmetry--3D assessment of infants with cleft lip & palate.

OBJECTIVES: To determine the degree of facial asymmetry in infants with unilateral cleft lip and/or palate, and quantify improvements following primary surgery, in three dimensions. DESIGN: The faces of 20 infants with unilateral clefts (10 UCL; 10 UCLP), and 20 age-matched, non-cleft controls, were captured using the C3D stereophotogrammetry system prior to primary lip/nose repair (at 3 months), at 6 months and at age 1 year. METHODS: Procrustes techniques were applied to 3D landmark configurations to its mirror image. Mean squared distances between landmarks and their antimeres were calculated and expressed as asymmetry scores for each 3D configuration. Full-face, nose and lip median scores were compared and changes with time evaluated (P < 0.01). RESULTS: There were no significant changes in asymmetry scores in the control group from 3 months to 1 year. The UCLP group was more asymmetric than the UCL group, displaying greatest improvement in nasal symmetry following primary repair. The lips continued to improve over time. The UCL group had significant nasal asymmetry, which did not appear to improve with primary surgery. CONCLUSIONS: Immediate improvement in asymmetry scores in children with UCLP is related to the production of a more symmetrical nasal form after primary surgery. In contrast, the nasal asymmetry seen in children with UCL is unchanged despite surgery. Full face asymmetry scores may mask subtle changes over time. Nasal and lip asymmetry should be considered individually.

Case-Control Studies↗

PubMed1997

Recent applications of the new stereology have thrown fresh light on how the human placenta grows and develops its form.

The availability of design-based stereological methods has made it possible to readdress certain key and contentious issues in placental growth and morphogenesis. Three particular questions are: (i) does the population of cytotrophoblast cells decline during gestation?, (ii) is placental growth biphasic or monophasic? and (iii) what are the consequences for intervillous porosity of the elaboration of terminal villi? These questions cannot be answered definitively without recourse to the new stereology. Applying the disector to estimate nuclear number and star volume to assess pore size, recent studies have helped to resolve these issues. Their findings are reviewed. Nuclei were counted in the trophoblastic epithelium, stroma and vascular endothelium of placental villi. It was found that growth is monophasic and proliferative. All types of nuclei increased in number throughout gestation and this included cytotrophoblast. Trophoblast grows by the continuous recruitment of new proliferative units of uniform mean volume. The so-called 'loss' of cytotrophoblast cells is a misinterpretation of what is seen on microscopical sections and is attributable to disproportionate growth in villous surface area. Cells simply become more widely dispersed. Elaboration of finer terminal branches on villous trees leads to a decline in the star volumes of villi and intervillous pores. Some of the functional implications of these findings are discussed.

Chorionic Villi↗

PubMed1997

Unbiased stereological estimation of the number and volume of nuclei and nuclear size variability in invasive ductal breast carcinomas.

The application of design-based stereological methods for estimating nuclear features quantitatively in invasive ductal breast cancer is described. Nuclear number, size and size variability are explored in relation to the tumour grade and patient prognosis. The study includes an examination of the efficiency in estimating different nuclear volumes, and two different estimators of the nuclear size variability are contrasted. Forty-two invasive ductal breast carcinomas diagnosed and graded by two pathologists were used. Both 5-microns and 25-microns-thick sections were obtained from paraffin blocks for stereological study. More undifferentiated tumours show significantly larger nuclei than low-grade tumours. The estimates based on the disector method demonstrate a decrease in the number of tumour cell nuclei per unit volume of tissue from grades 1 to 2 and especially from grades 2 to 3. The univariate survival analysis shows a high prognostic value of the nuclear volume estimates. The study shows that an efficient sampling procedure was performed, particularly when estimating volume-weighted mean nuclear volume using the point-sampled intercepts method. This method is more efficient than estimation of the number-weighted mean nuclear volume using the selector method; however, the latter provides paired estimates of volume- and number-weighted mean nuclear volume, as well as an estimate of the coefficient of variation of nuclear volume in the number distribution of the same cells.

Breast Neoplasms↗

PubMed2003

Semi-automated software for the three-dimensional delineation of complex vascular networks.

The understanding of tumour angiogenesis is of great importance in cancer research, as is the tumour response to vascular-targeted drugs. This paper presents software aimed at aiding these investigations and other situations where linear or dendritic structures are to be delineated from three-dimensional (3D) data sets. This software application was written to analyse the data from 3D data sets by allowing the manual and semi-automated tracking and delineation of the vascular tree, including the measurement of vessel diameter. A new algorithm, CHARM, based on a compact Hough transform and the formation of a radial map, has been used to locate vessel centres and measure diameters automatically. The robustness of this algorithm to image smoothing and noise has been investigated.

Blood Vessels↗

PubMed1996

Biostereometric quantification of clinical denture tooth wear.

In this study the wear of mandibular acrylic resin teeth opposed by porcelain maxillary teeth arranged in a lingualized occlusal scheme over a period of 3 years was measured. Six edentulous subjects received complete dentures as above and with three baseline markers of amalgam. At yearly intervals casts were made of the mandibular occlusal surfaces, including markers, and plotted by stereophotogrammetry. Volumetric loss of material was quantifiable. Ranges of 0.62-3.33 mm3/mm2 on the left side and 0.71-1.64 mm3/mm2 on the right were recorded. Friedman two-way ANOVA test indicated significant wear on teeth 35, 36, 45 and 46 but not on 34 and 44. A one-sided chewer displayed greater wear on the contralateral side, a finding difficult to explain.

Acrylic Resins↗

PubMed1998

Denture mobility with six degrees of freedom during function.

The purpose of this study was (1) to assemble and verify a system to measure the three-dimensional (3-D) movement of the upper and lower complete dentures and the movement of the mandible simultaneously, and (2) to analyse the relation between denture movements and the path of closure of the mandible during function. A 3-D motion capture system with four infrared TV cameras was used for this purpose. The relation between the dentures and the mandibular movements was analysed through the change of the inner product of normal vectors of the denture occlusal planes and mandibular planes. The mandibular movements were classified into two types; the normal stroke (the path of closure was on the ipsilateral side of mastication) and the reverse stroke (on the contralateral side). The results showed that the system could measure the denture mobility within a 0.3 mm error. The mobility of the upper dentures had a correlation to the path of closure of the mandible regardless of the working side or nonworking side, and the lower dentures had a tendency to move toward the working side.

Aged↗

PubMed2002

Dynamic influence of food consistency on the masticatory motion.

The masticatory cycle is a complex process and it depends on many factors. In our study we wanted to prove to what extent various types of food consistency influence the masticatory motions, especially the extent of forward, downward and lateral motions of the mandible. Nineteen study subjects aged from 20 to 37 years and with intact teeth rows were asked to chew three types of food of various consistency (banana, bread and carrot). The motions of the mandible were recorded by stereo-photo-grammetric system. Study results have shown that in all 19 study subjects the increase in food consistency increases the extent of masticatory motions. The average size of forward mandibular motion in all 19 study subjects when chewing banana amounts to 2.65 mm, when chewing bread it is 2.96 mm and 3.64 mm when chewing carrot. The average size of downward mandibular motion for all 19 study subjects amounts to 6.79 mm when chewing banana, 7.17 mm when chewing bread and 8.09 mm when chewing carrot. The average size of lateral mandibular motion in all 19 study subjects amounts to 2.46 mm when chewing banana, 2.80 mm when chewing bread and 3.40 mm when chewing carrot. Although varying from subject to subject, the masticatory cycle significantly depends on food consistency. By increasing the consistency of a mouthful, the extent of mandibular motion increases in every single study subject.

Adult↗

PubMed2004

Expression of the proliferating cell nuclear antigen and protein products of tumour suppressor genes in the human foetal testis.

Tumour suppressor genes retinoblastoma (Rb1) and adenomatous polyposis coli (Apc) as well as the proliferating cell nuclear antigen (PCNA) are involved in embryonic development. The purpose of the present study was to investigate the expression of Rb1 protein, APC protein and PCNA during development of the human foetal testis. Qualitative analysis of their expression at the single-cell level was performed using immunohistochemistry on archive samples of the foetal testis (18-37 gestation week). Stereological parameters (volume density, absolute volume, numerical density, absolute number) were calculated for quantification of the overall expression of those proteins that were expressed frequently enough for such an analysis. PCNA was frequently expressed in nuclei of immature Sertoli cells and prospermatogonia and less frequently in surrounding peritubular (myoid) and interstitial cells. The pRb1 protein was present in nuclei of prospermatogonia and Sertoli cells but was absent from the interstitial tissue. APC protein was expressed in the cytoplasm of a very small number of prospermatogonia and interstitial (Leydig) cells. The overall expression of PCNA in all stages of development was higher than pRb1 expression.

Adenomatous Polyposis Coli Protein↗

PubMed1997

Reconstruction of three-dimensional anatomical landmark coordinates using video-based stereophotogrammetry.

A method is described for reconstructing the 3-dimensional coordinates of anatomical landmarks from multiple video images. This method consists of 2 stages: (1) separate reconstructions of landmark coordinates visible in dorsal and ventral orientations using Direct Linear Transformation (Abdel-Aziz & Karara, 1972), and (2) least-squares alignment of the partial reconstructions using landmarks present in both. The repeatability of the overall reconstructions and of individual landmarks were assessed by performing multiple independent reconstructions of landmark coordinates for 2 camd specimens. Results indicate that the repeatability of interlandmark distances based on stereophotogrammetric reconstructions from standard-resolution video images is comparable to that of caliper measurement, and slightly superior to that of electronic 3-dimensional digitisation. At least 4 images should be available per landmark for optimal repeatability, but additional images allow only a slight increase in repeatability.

Animals↗

PubMed2003

A comparison of cup-to-disc ratio evaluation in normal subjects using stereo biomicroscopy and digital imaging of the optic nerve head.

The cup-to-disc (CD) ratio evaluated using stereoscopic biomicroscopy was compared with that evaluated by viewing a non-stereo digital image of the optic nerve head. Twenty normal subjects (mean age 26 +/- 4 years) were evaluated by two observers. The average CD ratio was 0.29 with a range of 0-0.80. The intra-class correlations between the observers ranged from 0.82 to 0.96, when comparing horizontal and vertical CD ratios for both evaluation techniques. The mean CD ratio was significantly smaller when viewing the digital image (0.25 +/- 0.01) compared with stereoscopic observation (0.33 +/- 0.03, p < 0.0001). Although the mean differences between the two techniques were small, the percentage of CD ratios that differed by >or=0.2 were between 5 and 25% of evaluations. Caution should be exercised when using stereoscopic and non-stereo digital evaluations of CD ratio interchangeably to assess longitudinal progression in a multi-clinician setting.

Adult↗

PubMed2000

A refined view of the determinants of gait: significance of heel rise.

OBJECTIVES: Although the major determinants of gait described by Saunders and colleagues have been accepted for more than 40 years, recent investigations raise the question of whether the reduction in center of mass (COM) displacement compared with a compass gait model indeed results from the factors originally described. We tested the hypothesis that heel rise at the end of stance is a true determinant that can explain a considerable portion of the reduction in COM vertical displacement during walking. DESIGN: Stereophotogrammetric data during walking were collected. A modified compass gait model incorporating the effect of heel rise, as compared with predictions based on a standard compass model, were used to estimate the isolated effect of heel rise on reducing the vertical displacement of COM. SETTING: A gait laboratory. PARTICIPANTS: Thirty able-bodied subjects. MAIN OUTCOME MEASURE: The estimated reduction in COM displacement due to heel rise was compared with the actual reduction in displacement. RESULTS: The estimated effect of heel rise on reduction in COM displacement was 23.4+/-7.6mm, whereas the actual reduction in COM displacement was 21.2+/-6.5mm (difference not significant, paired p = .185). CONCLUSION: During normal walking, heel rise from foot flat has a considerable role in raising the height of the COM when it is at its lowest, thus reducing its overall displacement. Insofar as reduction of COM vertical displacement may have important energy implications, appreciating the specific gait parameter of heel rise is key in rehabilitative approaches to improve gait disability.

Adult↗

PubMed2002

Length of the patellar tendon after anterior cruciate ligament reconstruction with patellar tendon autograft: a prospective clinical study using Roentgen stereometric analysis.

PURPOSE: This prospective study was designed to assess postoperative changes in patellar tendon length after removal of its central one third for anterior cruciate ligament (ACL) reconstruction using precise Roengen stereometric analysis (RSA). TYPE OF STUDY: Prospective clinical study. METHODS: Ten consecutive patients underwent arthroscopically assisted ACL reconstruction using the mid-third bone-patellar tendon-bone (BPTB) autograft. The tendon defect was left open and the paratenon was approximated with sutures. Tantalum beads were inserted in the distal part of the patella and in the tibial tuberosity through the bone defects. The distance between the tantalum markers in the patella and the tibial tuberosity was measured with RSA at the first day and at 1, 2, 3, 6, and 12 months after surgery. RESULTS: A decrease of patellar tendon length was observed in all cases. The amount of shortening averaged 1.6 mm (range, 0.5 to 3.2 mm), 3.2% of the initial length. In 4 patients, tendon shortening was detected during the first 4 weeks after surgery. In 6 cases, decrease of patellar tendon length started between the fourth and the eighth week. The shortening process continued in 8 knees until the 12th week. No further changes in patellar tendon length were observed after the 12th postoperative week. In 2 patients, shortening of the patella tendon exceeded 2 mm. The amount of patellar tendon shortening was not related to anterior knee pain. CONCLUSIONS: After removing the BPTB autograft, irreversible shortening of the remaining two thirds of the patellar tendon occurred during the first 12 postoperative weeks.

Adult↗

PubMed1999

Knee cartilage topography, thickness, and contact areas from MRI: in-vitro calibration and in-vivo measurements.

OBJECTIVE: This study assessed the three-dimensional accuracy of magnetic resonance imaging (MRI) for measuring articular surface topographies and cartilage thicknesses of human cadaveric knee joints, by comparison with the calibrated stereophotogrammetric (SPG) method. METHODS: Six fresh frozen cadaveric knees and the knees of four volunteers were imaged with a three-dimensional spoiled gradient-recalled acquisition with fat suppression using a linear extremity coil in a 1.5 T superconducting magnet. The imaging voxel size was 0.47 x 0.47 x 1.0 mm. Both a manual and a semi-automated segmentation method were employed to extract topographic measurements from MRI. Following MRI, each of the six cadaveric knees was dissected and its articular surfaces quantified using stereophotogrammetry. The MRI surface measurements were compared numerically with the SPG measurements. RESULTS: For six cadaveric knees, the average accuracies of cartilage and subchondral bone surface measurements were found to be 0.22 mm and 0.14 mm respectively and the thickness measurements demonstrated an average accuracy of 0.31 mm. It was found that while most of the error may be attributed to random measurement error, the accuracy was somewhat affected by systematic errors. For each bone of the knee, accuracies were most favorable in the patella, followed by the femur and then the tibia. The more efficient semi-automated method provided equally good and sometimes better accuracies than manual segmentation. CONCLUSIONS: This study demonstrates that clinical MRI can provide accurate measurements of cartilage topography, thickness, contact areas and surface curvatures of the knee.

Adult↗

PubMed2000

An in vitro study of the accuracy of a new protocol for planning distraction osteogenesis of the mandible.

PURPOSE: The purpose of this study was to determine the in vitro accuracy of a new protocol for distraction osteogenesis of the mandible that involves a planning process and a surgical technique. MATERIALS AND METHODS: An experimental design was developed to simulate distraction osteogenesis on stereolithographic models of patients with craniofacial deformities. All patients had previously undergone 3-dimensional computerized scans of the craniofacial skeleton. The data from these scans were used to generate stereolithographic models. Before the fabrication of the models, the computed tomography (CT) data were manipulated to add a series of rulers and markers to the models. The 3-dimensional computerized scans were also used as the basis of the planning process. They were imported into an animation software (3D-Studio Max; Discreet, Montreal, Canada), and a virtual distractor was built and installed on the model, and the osteotomies and distraction processes were simulated. Finally, a recipe for sequencing the linear and angular changes of the distractor were calculated. A surgical technique was developed to facilitate the precise installation of the distractor as indicated in the presurgical plan. The transfer of information regarding pin position and orientation from the computer model to the patient was accomplished by creating a surgical template. This template was designed in the computer and fabricated by use of stereolithography. Mock surgery was performed on the stereolithographic models, and the results were compared with those predicted by the computer. The difference between the actual position and the predicted position was recorded. RESULTS: On the X-axis, the difference between the predicted position for the condylar marker and the actual position of the marker on the stereolithographic models was 0.6 +/- 1.1 mm. On the Y-axis, the difference between the predicted position for the condylar marker and the actual position of the marker on the stereolithographic models was -0.9 +/- 2.6. On the Z-axis, the difference between the predicted position for the condylar marker and the actual position of the marker on the stereolithographic models was 0.04 +/- 0.8 mm. There was excellent correlation between the predicted and the actual measurements for the X, Y, and Z axes: 0.98, 0.93, and 0.98, respectively. CONCLUSIONS: The results indicate that the combination of this planning process and surgical technique was very accurate. This in vitro study is the first step in determining the clinical usefulness of this protocol. If the results of this study are validated in clinical practice, this protocol will allow clinicians to improve the clinical outcomes of patients treated with distraction osteogenesis.

Analysis of Variance↗

PubMed2001

Radiographic stereophotogrammetric evaluation of intersegmental stability after mandibular sagittal split osteotomy and rigid fixation.

PURPOSE: The purpose of this study was to determine if rigid fixation with bicortical screws and/or miniplates with monocortical screws prevent mobility at the osteotomy site after bilateral mandibular sagittal split osteotomy. PATIENTS AND METHODS: Three metal bone markers were inserted in the proximal and the distal segments of the mandible during the sagittal split operation in 10 patients. These served as measurement points in postoperative follow-up by radiographic stereophotogrammetry. The patients were examined at intervals during the first postoperative year. At each examination, 2 sets of radiographic stereograms were obtained: 1 in rest position and 1 with stress applied to the osteotomy sites. The difference in the position of the proximal segment in relation to the distal segment between the 2 sets of stereograms was recorded. Findings greater than 0.4 degrees and 0.2 mm change indicated true displacement of the bone segments. RESULTS: Immediately after surgery, mobility at of the osteotomy site(s) was found in 8 of 10 patients, and after 1 year it was still present in 4 patients. CONCLUSIONS: Fixation with bicortical screws or miniplates and monocortical screws does not prevent mobility at the osteotomy site after sagittal split osteotomies. This mobility may remain as long as 1 year after surgery. The term "rigid fixation" is thus not a proper term for this kind of fixation.

Adolescent↗

PubMed2001

Concave versus posterior-stabilized tibial joint surface in total knee arthroplasty: randomized evaluation of 47 knees.

Forty-seven knees in 43 patients with severe deformities randomly received AMK total knee arthroplasty with concave (C, n = 25) or posterior-stabilized (PS, n = 22) polyethylene insert and with resection of the posterior cruciate ligament. Radiostereometric examinations were done postoperatively and after 3, 12, and 24 months. Two patients (1 C, 1 PS) underwent revision surgery. At the 2-year follow-up, the median absolute rotations of the tibial inserts ranged from 0.13 degrees to 0.26 degrees (C vs PS; P =.1-.7). The maximum total point motion was almost identical in the 2 groups (C, 0.38; PS, 0.39; P =.9). Maximum subsidence, lift-off, and Hospital for Special Surgery scores did not differ (P =.1-.6). Recipients of 20 of 24 knees with concave design and 14 of 19 knees with posterior-stabilized design reported that their knee could be regarded as normal or almost normal. Variations of the configuration of the polyethylene insert did not alter the outcome in the short term.

Aged↗

PubMed2001

Micromotion between the half bearings in the interax prosthesis: a roentgen stereophotogrammetric analysis.

We assessed the migration and movement between the half-bearings of the Interax prosthesis in 18 patients using roentgen stereophotogrammetric analysis (RSA). This study showed movements of the tibial component even in successful knee arthroplasty: 17 prostheses migrated only initially and remained stable after 1 year, whereas 1 prosthesis migrated consistently throughout 3-year follow-up. RSA revealed no or minimal displacement between the half-bearings until the 4-year follow-up, confirming that their fixation to the baseplate was adequate. In the case of loosening, a rotation about the longitudinal axis of 1.3 degrees and a medial-lateral translation of 0.5 mm was observed between the half-bearings. Cold flow was revealed by RSA in the posterior region of the medial half-bearing.

Aged↗

PubMed2002

A roentgen stereophotogrammetric analysis of unicompartmental knee arthroplasty.

Roentgen stereophotogrammetric analysis (RSA) was used to investigate the stability of the tibial component in unicompartmental knee arthroplasty. Twenty patients were implanted with a Howmedica Duracon UNI prosthesis (Limerick, Ireland) and studied for an average follow-up of 30 months. In most cases, the displacements detected at 1-year follow-up were small (ie, not exceeding 0.5 mm for translations and not exceeding 1.0 degrees for rotations). Only 1 patient showed signs of mechanical loosening as the prosthesis continued to migrate, reaching 3.2 mm of total motion at 4-year follow-up. RSA did not show any deformation in the polyethylene except for the case of loosening. The clinical results were excellent and good according to the Hospital for Special Surgery scoring system. No correlation was found among demographic, clinical, and RSA data.

Aged↗