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At least 1,117 records · Page 62Linked to original sources
PubMed1991

Clinical and roentgenographic evaluation of hydroxyapatite-coated and uncoated porous total hip arthroplasty: a preliminary report.

Sixty osteoarthritic patients undergoing primary uncemented total hip arthroplasty were matched for age and weight and randomized into one of four groups with respect to implant coating and postoperative protected weight-bearing status: group 1, hydroxyapatite, 12 weeks; group 2, uncoated, 12 weeks; group 3, hydroxyapatite, 6 weeks; group 4, uncoated, 6 weeks. Tantalum spheres were implanted periprosthetically into the femur at the time of arthroplasty, thus providing constant references for stereoscopic radiographs. Patients were then evaluated over a 1-year period with clinical examination, plain radiography, and roentgen stereophotogrammetric analysis (RSA). Clinical evaluation using Charnley scoring showed no significant preoperative or postoperative intergroup differences, whereas visual analog testing noted less thigh pain with hydroxyapatite-coated stems at 12 weeks and 6 months follow-up. Plain radiographic analysis produced no significant differences, with no instability detected and bony ingrowth noted uniformly in all groups. The preliminary stereographic evaluation showed migration in all groups, but there were no significant differences between coated and uncoated stems or 6-week and 12-week partial weightbearing protocols. The Charnley, plain radiographic, and preliminary stereogrammetric evaluations all suggest that migration is unaltered by enhanced surfaces and that early unprotected weightbearing does not jeopardize implant fixation regardless of coating design. The lower incidence of visual analog thigh pain with the hydroxyapatite-coated stems, however, may be a reflection of bony ingrowth and as such add some validity to the theoretical advantages of enhanced surface prostheses.

Aged↗
PubMedDate not supplied

Two-dimensional wound measurement: comparison of 4 techniques.

Two- and three-dimensional wound measurement techniques are documented in the literature and used clinically, as well as in research. The purpose of this study was to compare 4 two-dimensional wound measurement techniques: linear length and width using a ruler, planimetry, computerized stereophotogrammetry (SPG) length and width, and computerized SPG area. Three plaster of Paris wound models were developed and baseline measurements of outer wound perimeters obtained via a Coordinate Measuring Machine. The convenience sample of raters included 66 upper-division baccalaureate nursing students, graduate nursing students, nursing staff, and wound care nurses. Each rater measured each wound twice in a randomly assigned order of methods written on a card drawn from an envelope. The least biased technique was the computer area, followed in order by the computer length and width, planimetry, and ruler length and width. The most accurate technique, given multiple raters, was determined by the standard error of measurement. The smallest standard error of measurement, thus the most accurate, was the computer area technique, followed in order by the ruler length and width, computer length and width, and planimetry. Interrater reliability of average ratings was high; only the SPG area measurements for single ratings were reliable enough for clinical or research purposes. Intrarater reliability was high for methods with low interrater reliability, suggesting that nurses are consistent in the direction of personal error.

Adult↗
PubMed1999

[Comparison of the reliability of two 3D acquisition systems used for the study of anthropometric and postural parameters].

The goal of this study is to compare the between trials and between session reliability of the postural geometry (PG) and anthropometrical evaluations, obtained by the FreePoint (FP) system and the Motion Analysis System (MA). The potential of automatization of the anthropometric evaluation is also evaluate through the comparison of height measurements obtained by the two 3D systems and traditional anthropometrical tools. The PG of 15 adult control subjects (x: 25 years, SD: 6) evaluated on two occasions (1 week interval) and a mannequin on one occasion were evaluated with both systems. Each evaluation involved the identification of 52 anatomical landmarks followed by the acquisition of 5 trials with each system. The 3 dimensional position of the anatomical landmarks serves to define a postural model including the shoulder girdle, spinous processes (T1 to S1), thorax, pelvis, lower extremities and base of support. Postural parameters were calculated, including rotations, tilts, versions, kyphosis, lordosis, right and left Cobb, anteroposterior shifts, (AP), mediolateral shifts (ML) and vertical heights. The between trials and between session results demonstrate a strong correspondence of the 15 anthropometric heights and the 20 postural parameters between the three systems, permitting the proposal of a broadened clinical utilisation of the FreePoint system. However, the validity of these measures is influenced by the reliability of the anthropometric landmarking, natural oscillation of the body and the intra-specific variation of the posture of each subject.

Adult↗
PubMedDate not supplied

Precision of CNC-milled titanium frameworks for implant treatment in the edentulous jaw.

PURPOSE: The purpose of this report was to describe a new technique to fabricate one-piece, implant-supported titanium frameworks by means of a computer numeric-controlled (CNC) milling technique, and to compare the fit of these frameworks with conventional cast prostheses. MATERIALS AND METHODS: The study comprised 20 patients who were provided with 5 standard Brånemark implants each in the edentulous mandible. The fit of the first 10 prostheses with CNC-milled frameworks was measured by means of a 3-dimensional photogrammetric technique. The distortion of the center point of the framework cylinders was measured in relation to the master cast replicas. These measurements were compared with 10 randomly selected routine prostheses with cast frameworks. RESULTS: No significant differences were found between the 2 groups. The 3-dimensional distortion of the cylinders in the completed prostheses ranged from 3 to 80 microns; no passive framework was observed. More distortion was observed in the horizontal plane (x and y axes) as compared to the distortion in the vertical direction (z axis). CONCLUSION: The precision of fit of the first CNC-milled prostheses presented a comparable fit to the conventional cast frameworks. Consequently, this new technique could be a valid option for the routine fabrication of frameworks for implant prostheses.

Computer-Aided Design↗
PubMed1999

Accuracy verification of the photostereometric system KKN/1B developed for intraoperative measurement of knee movement immediately after total knee arthroplasty.

The function and integrity of the knee joint following total knee arthroplasty (TKA) is determined at first by the design and implantation of the prosthesis, and later by the tension of soft tissues surrounding it. Accurate post-TKA motion data obtained intraoperatively could be used not only to optimize implantation techniques from a kinematic standpoint, but also to improve prosthetic design. We therefore developed a system specifically geared to photostereometric measurement of 6 d.o.f. knee motion. A total of eight LEDs are mounted on the prosthetic components in two sets of four by means of connecting measuring-bows. The positions of the LEDs are detected in three-dimensions by two sets of three linear CCD cameras, located bilaterally relative to the knee. The position and orientation of the femoral component relative to the tibial one are estimated from the positions of all LEDs in the sense of least-squares. Based upon results of various accuracy validation experiments performed after precise camera calibration, static overall accuracy and spatial resolution were considered to lie within 0.52 and 0.11 mm, respectively, at any point on the femoral articular surface.

Arthroplasty, Replacement, Knee↗
PubMed2000

Comparative examination of the accuracy of a mechanical and an optical system in CT and MRT based instrument navigation.

The aim of an intraoperative instrument navigation system is to support the surgeon in the localization of anatomical regions and to guide the use of surgical instruments. An overview of technical principles and literature reports on various navigation systems is provided here. The navigation accuracy (tested on a plastic phantom under simulated operating room conditions) of the mechanical Viewing Wand system and the optical SPOCS system amounts to 1 to 3 mm for computerized tomography (CT) data, with a significant inverse dependence on the layer thickness. The values for magnetic resonance tomography (MRT) data are significantly higher. In regard to the choice of registration points, a statistically inverse dependence exists between the number of points and the distance between the points. During the time period between autumn 1993 and mid-1999, more than 120 clinical applications were performed. The intraoperative accuracy was in the range of < or = 3 mm. Registering the patient position with preoperatively inserted screw markers achieved accuracy values of < or = 2 mm. The instrument navigation technique has proved to be very advantageous for the spatial orientation of the surgeons. The possibility of checking resection borders has opened up new perspectives in tumor surgery. A quality improvement and a reduction of the operational risks as well as a considerable decline in the stress placed on the patient can be expected in the near future due the techniques of computer-assisted surgery.

Humans↗
PubMed1975

Close-range stereophotogrammetry and coupled stress analysis as tools in the development of prosthetic devices.

The combination of molding at physiologic pressures, close-range stereophotogrammetric processing, geometric smoothing, finite element analysis, leaflet thickness measurements, and a knowledge of leaflet properties have provided a description of asymmetric geometry and stress patterns within a normal human aortic leaflet which are consistent with anatomic observations. A predominantly circumferential, tensile pattern of stress resultants was found. The higher values of stress resultants coincide with thinner regions of the leaflet. And those in a coronary leaflet. A design stress magnitude of 80 Gm/mm2 for a long pressure of 110 mm Hg, based on the actual thickness of the leaflet, was considerably greater than that previously reported in the literature. Those responsible for device development in the future must consider the mechanical properties and asymmetric geometries in design. Future generation devices will depend on the ability of the designer and the fabricator to incorporate features of asymmetry, anisotrophy, and deformation characteristics which match those of living tissue. Through such efforts more durable devices will result.

Aortic Valve↗
PubMed1975

[Method for the functional evaluation of contrasted vessels of the lungs with the aid of stereoroentgenogrammetry and morphometry].

A complex method for measuring vessels of the lungs is suggested; the method includes a number of successive procedures: contrasting of vessels under physiological pressure, stereoscopy of the preparation of the lung in a non-atelectatic and non-fixed state and obtaining of stereopaired angiograms, marking the levels of branching of vessels and determination of their lumen by means of stereocomparator, fixation of the lung, spot cutting and morphometry of the wall of the same segments of the lung vessels. The size of the lumen of the vessel approximating the intravital one, was combined with morphometric parametres of its wall and indices were calculated characterizing a morpho-functional state of the blood flow bed of the lungs.

Angiography↗
PubMed2001

[Opto-electronic techniques and 3D body surface reconstruction for the control of patient positioning in the radiotherapy of breast cancer].

PURPOSE: In radiotherapy clinical practice, the currently existing gap between the high degree of accuracy in treatment planning and, the possibility of conforming the high-energy radiation beams on the one hand, and the uncertain set-up of each irradiation session on the other is a decisive factor for optimizing radiation treatment. Indeed there is wide experimental evidence that the current methods used for patient alignment and immobilization do not guarantee the necessary precision in delivering therapy with respect to the specifications of the treatment plan. The main reason for this is the lack of control systems that may be applied systematically to provide quantitative real-time feedback on the quality of patient repositioning and immobility during radiation emission. MATERIAL AND METHODS: Opto-electronic techniques and body surface registration methods were sygergisically used for the automatic three-dimensional verification and correction of patient position at the therapy unit. The method is based on radiotherapy applications of real-time opto-electronic human motion analysis using passive markers to control patient repositioning and to acquire and describe body surfaces in three dimensions. The quantitative detection of the localization error relies on the real-time detection of the position of an hybrid set of control points, namely physical passive markers and laser light markers, and their immediate comparison with a reference data set. The data set consists of the reference positions of the passive markers and a three-dimensional model of the body surface. The method was experimentally tested at the Radiotherapy Division of the European Institute of Oncology to control the repositioning of a phantom and of a volunteer, with reference to the clinical realignment procedure applied for breast cancer radiotherapy. RESULTS: The results confirm that the technique represents a valuable method to detect and automatically correct localization errors in the irradiation set-up. The use of the information provided by the laser markers allows one to reduce the potential inaccuracies in the manual relocation of the passive markers on the subject's skin and guarantees that position control is based on a redundant set of data describing the three-dimensional localization and configuration of the irradiated body surface portion. The experimental results show that the initial displacements of the controlled body area were systematically reduced to median values below 1 millimeter and 1.2 millimeters for the phantom and the volunteer, respectively. CONCLUSIONS: The synergistic use of opto-electronic technologies and stereophotogrammetric techniques associated to surface registration methods proved to provide an accurate description of the spatial transformation between the reference position and the actual position of the controlled body area. This allowed us to define an effective procedure to correct the patients position and recover the quality of the irradiation set-up, in agreement with the clinical requirements. The reported results confirm that the dynamic sensing of the body surface by opto-electronic technologies is a particularly promising technique that allows to systematically achieve swift and accurate patient alignment, thus ensuring that the treatment plan specifications are reproduced in the reality of each irradiation session.

Algorithms↗
PubMed2001

[Inferring landmark displacements from changes in cephalometric angles].

OBJECTIVE: To investigate the appropriateness of using changes in angular measurements to reflect the actually profile changes. METHODS: The sample consists of 48 growing malocclusion patients, contained 24 Class I and 24 Class II subjects, treated by an experienced orthodontist using Edgewise technique. Landmark and superimpositional data were extracted from the previously prepared numerical database. Three pairs of angular and linear measures were computed by the Craniofacial Software Package. RESULTS: Although the associations between all three angular measures and their corresponding linear measures are statistically significant at the 0.001 level, the disagreement between these three pairs of measures are 10.4%, 22.9% and 37.5% respectively in this sample. CONCLUSIONS: The direction of displacement of anterior facial landmarks during growth and treatment cannot reliably be inferred merely from changes in cephalometric Angles.

Cephalometry↗
PubMed2001

[The establishment of three-dimensional soft tissue facial reconstruction and morphometry].

OBJECTIVE: To establish a digital three-dimensional facial soft tissue morphometry and reconstruction system for orthodontic diagnosis and analysis of the facial soft tissue. METHODS: Three-dimensonal characteristics of facial soft tissue were captured by 4 digital cameras of high resolution. The developed hardware and software system and stereophotogrammetry were used for three-dimensional facial soft tissue reconstruction and morphometry at the same time. RESULTS: The three-dimensional facial soft tissue were successfully reconstructed with high reality and the three dimensional facial image can be rotated, moved and zoomed on the purpose. The system has the following advantages: (1) rapid capture of the facial image within 1 second or so, (2) accurate identification of facial landmark within 0.5 mm of resolution, (3) easy manipulation, (4) no exposure to radiation. CONCLUSIONS: The established system has proved to be effective for three-dimensional facial soft tissue diagnosis and analysis with the advantages of high resolution, high speed and, no exposure to radiation.

Face↗
PubMedDate not supplied

Comparison of deformation by stereophotogrammetry of various kinds of major connectors in maxillary Kennedy Class I removable partial dentures.

PURPOSE: Major connectors must be rigid to perform their functions with maximum efficacy. This study investigated the deformation of four major connectors for maxillary Kennedy Class I removable partial dentures. MATERIALS AND METHODS: The designs were palatal plate, U-shaped plate, palatal strap, and anteroposterior bar. The deformation properties of major connectors were comparatively analyzed by two methods. In the photogrammetric part, a stereometric camera, Avipan-100 glass films, and an analytic apparatus were used. A computerized hydraulic machine was programmed to load the eight test dentures at 4-Hz frequency under a vertical load of 100 kg and a maximum of 300,000 cycles. The fluorescence penetrant liquid inspection test was used to detect the surface microcracks. RESULTS: The anteroposterior bar showed the least deformation. The other connectors, ranked in increasing order for the amount of deformation, were the U-shaped plate, the palatal strap, and the palatal plate. There were no microcracks in the U-shaped plate and the anteroposterior bar designs. CONCLUSION: Anteroposterior bar major connectors showed the least deformation among the maxillary major connector types tested. Microscopic cracks were seen in major connectors showing the highest degree of deformation and located at the depth of the hard palate.

Acrylic Resins↗