SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
30 ankles in 27 patients operated on for chronic lateral instability with tensioning of the lateral ligaments and capsular tissue were examined using RSA preoperatively, at 20 and 60 months. 28 ankles were considered excellent or improved by the patients. Mechanical stability (talar adduction and translation) was increased without compromising the passive range of motions.
60 patients with arthrosis who received a Charnley total hip replacement were randomly assigned to either an uncemented porous Harris-Galante type I socket or a cemented all-polyethylene Charnley socket. Socket migration and rotation were studied by radiostereometry (RSA) for 2 years. After 2 years, all sockets were still in situ. There was no difference in migration or rotation between the 2 socket designs, nor was there any difference in pain or function. We conclude that the initial fixation of the Harris-Galante socket resembles that of the Charnley socket.
Tibial migration in 33 cementless total knee replacements, which were performed with a cooled saw blade vs. a conventional blade, was studied in a randomized prospective study using roentgen stereophotogrammetric analysis (radiostereometry). All cases were clinically successful after 2 years and inducible displacement was smaller in the group operated with the cooled saw blade. This group also had a tendency towards less continuous migration.
We assessed the accuracy of migration measurements on conventional and digitized radiographs of total hip arthroplasties by comparing the results with radiostereometry (RSA). 4 stem and 3 acetabular designs were studied. 2 of the stem designs and 1 cup design were uncemented. 180 manual and 202 digitized measurements were done on 120 conventional radiographic examinations. The readings on digitized radiographs did not differ from the manual measurements on the same radiographs. A comparison of the measurements from plain radiographs and with RSA of the femoral stems revealed an accuracy (absolute mean + 2 SD) of between 3.9 and 12.3 mm, depending on the choice of landmarks. The greatest accuracy was obtained by using tantalum markers inserted into the greater or the lesser trochanter and the shoulder of the stem. The most medial point of the lesser trochanter proved to be the best bony landmark. Measurements, including both the center of the femoral head and the greater trochanter, were associated with poor accuracy. The accuracy as regards horizontal cup migration varied from 4.4 to 6.5 mm and the accuracy as regards vertical migration varied between 4.4 and 6.3 mm. The intraobserver error (2 SD) ranged from 1.6 mm to 5.6 mm, The corresponding figures for the inter-observer error were 2.6 mm and 6.6 mm, respectively. One of the cemented cup designs was associated with inferior accuracy. Stem design did not affect the accuracy.
We compared Boneloc bone cement with conventional cement (Palacos) in fixating the tibial component during 2-5 years in 19 patients with gonarthrosis undergoing total knee arthroplasty in a prospective randomized study. Boneloc displayed significantly larger migration, subsidence and lift-off than Palacos. The difference was identifiable already within 3 months postoperatively, but became significant at 12 months. In the Boneloc group, all components showed subsidence of the posterior part and lift-off of the anterior part of the tibial component, whereas in the Palacos group, the locations of subsidence and lift-off were evenly distributed about the edge of the implant. At 5 years, both Boneloc knees so far investigated were clinical failures with high migration rates. We conclude that, even in total knee arthroplasty, there is a substantial risk that Boneloc leads to inferior clinical results, but later than in hip replacements.
To evaluate whether a Hoffmann-Slätis frame can reduce movements in the sacroiliac joints, 10 patients (7 women) with severe posterior pelvic pain of long duration were externally stabilized. The movements were analyzed with radiostereometric analysis (RSA) in supine and standing positions, preoperatively and postoperatively with the frame applied. In 2 patients, there was no reduction in the movements with the frame, perhaps because it was not properly tightened. In the remaining 8 patients, the median reduction in rotation was 55% on the left side and 63% on the right side around the helical axes, and 74% around the x-axes on the left side and 66% on the right side. Our data suggest that external fixation using the Hoffmann-Slätis frame, substantially reduces sacroiliac joint mobility in some patients, which must be considered when using the frame as a diagnostic tool. Pre-stressing the frame by tightening the vertical bars before the compression bar is applied is recommended to reduce the risk of this shortcoming.
33 patients (22 men), median age 54 (40-68) years, with medial gonarthrosis grades 1-3, were treated by closed-wedge osteotomy (high tibial osteotomy = HTO, n 16) or open-wedge osteotomy by hemicallotasis (hemicallotasis osteotomy = HCO, n 19). 2 patients were operated on bilaterally. The patients were studied by RSA (radiostereometric analysis) for measuring 3-D changes in the correction achieved. In the HTO group the RSA measurements were obtained at the time of plaster removal, 1 month later and 1 year after surgery. In the HCO group, the RSA measurements were performed at the time of removal of the external fixator, 1 month later and 1 year after surgery. After removal of the fixation, HTO was associated with increased medial/lateral and distal translation of the proximal segment, compared to HCO. In addition, the tibial plateau rotated more around the longitudinal axis of the tibia after HTO.
Craniectomy was performed on a boy with Crouzon's disease at 22 months of age. Metallic implants (tantalum balls, 0.5 mm in diameter) were inserted in the calvaria during surgery, and the child was examined postoperatively by roentgen stereometry at intervals of about 100 days (total observation time, 309 days). The thyroid radiation dose was 250 muGy for one examination. The effect of craniectomy was recorded with a high degree of accuracy in terms of motion of bones and volume changes in the calvaria. Expansion occurred almost entirely through motion of free bone flaps in the frontal region, while a linear craniectomy in the region of the sagittal suture caused small changes. The rate of expansion decreased rapidly and stabilization was recorded about 250 days after surgery.
This investigation was conducted to further elucidate both the significance of a calvarial suture and the compensatory ability of the cranial vault. Four-week-old male New Zealand White rabbits were subjected to unilateral or bilateral extirpation of the coronal suture after insertion of metallic markers, and were then followed regularly by roentgen stereophotogrammetry until age 21 weeks. Bilateral extirpation of the normal coronal suture resulted in a dramatically increased initial rate of bone separation, which tended to remain supranormal for the rest of the investigation. Unilateral suturectomy showed differences in growth between the sides, the operated side initially separating significantly more than the other. Volumetric calvarial growth in rabbits with unilateral extirpation terminated similar to that in control animals, while volumes in rabbits with bilateral extirpations constantly exceeded control volumes, finally exceeding these by 65%. Responses at intact sutures confirmed the compensatory capacity of cranial vaults. The results indicate that the passive longitudinal and volumetric cranial vault bone growth responds quickly to growth disturbances, thereby demonstrating its plasticity, and that the neurocranial suture is a restraining and modulating component in cranial growth.
The effect of temporary fusion of sutures on craniofacial growth was studied biometrically in 4-week-old male New Zealand White rabbits. Tantalum bone markers were implanted in the cranial vault, and the coronal suture immobilized with isobutyl-2-cyanoacrylate adhesive. Linear craniectomy was performed after 2 or 6 weeks of sutural growth restriction (four animals in each group). The animals were followed for approximately 17 weeks. Early craniectomy resulted in greatly increased coronal suture bone separation (175% of control growth rates in peers and 125% of maximal control rates). Growth after late craniectomy showed an age-dependent lower rate, but still the overshoot markedly surpassed controls (210% of control rates in peers and 65% of maximal control growth rates). Overall, both exhibited overcompensation in coronal suture growth. A rapid compensation of adjacent sutures to temporary growth restriction and a tendency toward spontaneous correction following release of growth inhibition were demonstrated. Thus, the total anteroposterior growth of the combined frontonasal and coronal sutures nearly equaled that of control animals. Following linear craniectomy, volumetric calvarial expansion increased considerably in both early and late groups, due to compensatory coronal suture growth, but probably due also to spatial bone rearrangements. Based upon the findings, the length of the suture immobilization period seems critical to longitudinal and volumetric growth as well as to subsequent compensatory activity after surgical correction.
OBJECT: In a nondestructive, repeated-measures in vitro flexibility experiment, the authors compared the acute stability of C1-2 after placement of C-1 lateral mass and C-2 pars interarticularis (LC1-PC2) instrumentation with that of C1-2 transarticular screw fixation. METHODS: The effect of C-1 laminectomy and C1-2 interspinous cable/graft fixation on LC1-PC2 stability was studied. Screw pullout strengths were also compared. Seven human cadaveric occiput-C3 specimens were loaded nondestructively with pure moments while measuring nonconstrained atlantoaxial motion. Specimens were tested with graft alone, LC1-PC2 alone, LC1-PC2 combined with C-1 laminectomy, and graft-augmented LC1-PC2. Interspinous cable/graft fixation significantly enhanced LC1-PC2 stability during extension. After C-1 laminectomy, the LC1-PC2 construct allowed increased motion during flexion and extension. There was no significant difference in lax zone or range of motion between LC1-PC2 fixation and transarticular screw fixation, but graft-assisted transarticular screws yielded a significantly smaller stiff zone during extension. The difference in pullout resistance between C-1 lateral mass screws and C-2 pars interarticularis screws was insignificant. The LC1-PC2 region restricted motion to within the normal range during all loading modes. Atlantal laminectomy reduced LC1-PC2 stability during flexion and extension. CONCLUSIONS: The instrumentation-augmented LC1-PC2 construct performed biomechanically similarly to the C1-2 transarticular screw fixation. The LC1-PC2 construct resisted flexion, lateral bending, and axial rotation well. The weakness of the LC1-PC2 fixation in resisting extension can be overcome by adding an interspinous graft to the construct.
Explore the source record for details and available documents.
Thirty adult dry-bone ilium specimens were used in conjunction with computer analysis to determine the average articular contact area between the sacrum and ilium at the sacroiliac joint. Simulating an unstable pelvic injury, the sacroiliac joint was displaced in three directions by moving the ilium posteriorly, superiorly, and posterosuperiorly. After each displacement, the contact area between the sacrum and ilium at the sacroiliac joint was calculated. The data showed that the average articular surface area of the male sacroiliac joint (1138.3 mm2) was approximately 12.8% greater than the average surface area of the female sacroiliac joint (992.5 mm2). The average articular contact area between the sacrum and ilium at the sacroiliac joint was lowest with the ilium displaced posterosuperiorly compared to equal displacements superiorly or posteriorly. This study quantitatively illustrated the loss of contact surface area between the sacrum and ilium during various displacements of the ilium, thus indicating the clinical cross-section area available for open reduction and internal fixation or fusion.
PURPOSE: To compare the elevation accuracy of placido-based videokeratoscopes with a rasterphotogrammetry-based topography system using models of an aspheric surface and a simulated myopic ablation. METHODS: Test surfaces representative of normal corneas and corneas after excimer ablation were fabricated from a material measurable using both reflective (placido) and projective (rasterstereographic) systems. The "normal" surface was a rotationally symmetric asphere, while the simulated photorefractive keratectomy ablation had a central 5.5 mm diameter clear zone with a 1 mm blend radius to eliminate surface discontinuity. The surfaces were measured with their axes of symmetry aligned with the instrument axis, and again with their axes tilted downward by 10 degrees to produce a nonsymmetric shape. RESULTS: All of the topography systems performed reasonably well in measuring the aspheric surface, with root mean square elevation error ranging from 1.2 to 14.3 microm. The rasterstereographic system had a root mean square error of 4.7 microm on the simulated ablation, while the placido systems had root mean square errors of 10.6 to 29.5 microm. Tilting the surfaces did not significantly alter the results. CONCLUSIONS: The tested placido videokeratoscopes do not provide reliable elevation data for shapes that have nonlinear changes in curvature. This may have serious implications if these systems are used for postoperative analysis or contact lens fitting on corneas that have been modified by refractive procedures.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
There is little knowledge of the functional performance of patients with talocalcaneal coalition because of the marginal quantitative information accessible using current motion-analysis and plantar pressure-measurement techniques. A novel system was developed for comprehensively measuring foot-floor interaction during the stance phase of gait that integrates instrumentation for simultaneously measuring bony segment position, ground reaction force, and plantar pressure with synchronization of spatial and temporal variables. An advanced anatomically based analysis of foot joint rotations was also applied. Tracking of numerous anatomical landmarks allowed accurate selection of three footprint subareas and reliable estimation of relevant local forces and moments. Eight patients (11 feet) with talocalcaneal coalition were analyzed. Major impairment of the rearfoot was found in nonsurgical patients, with an everted attitude, limited plantarflexion, and overloading in all three components of ground reaction force. Surgical patients showed more normal loading patterns in each footprint subarea. This measuring system allowed for accurate inspection of the effects of surgical treatment in the entire foot and at several footprint subareas. Surgical treatment of talocalcaneal coalition seems to be effective in restoring more physiologic subtalar and forefoot motion and loading patterns.
Soft tissue changes following correction of mandibular hyperplasia were studied using a laser system for three-dimensional (3-D) surface measurement. Twelve subjects (7 men and 5 women; age 17-48 years) were included in this study. Bilateral sagittal split ramus osteotomies were performed in ten patients and intraoral vertical ramus osteotomies in two patients. Pre- and postoperative images, obtained with the laser system, were superimposed to determine distribution of changes in the perioral soft tissue. Mean volume changes were 1032.3 mm3 in the Subnasale-UL area and 8700.9 mm3 in the LL-Menton area. Changes in both areas were symmetrical around the mid-sagittal plane in some patients and asymmetrical in others. This measurement system provided a simple method of determining 3-D changes in soft tissue following surgery and might be useful for clinical purposes.