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PubMed2001

Dynamic wedge versus physical wedge: a Monte Carlo study.

The purpose of this study is to analyze the characteristics of dynamic wedges (DW) and to compare DW to physical wedges (PW) in terms of their differences in affecting beam spectra, energy fluence, angular distribution, contaminated electrons, and dose distributions. The EGS4/BEAM Monte Carlo codes were used to simulate the exact geometry of a 6 MV beam and to calculate 3-D dose distributions in phantom. The DW was simulated in accordance with the segmented treatment tables (STT). The percentage depth dose curves and beam profiles for PW, DW, and open fields were measured and used to verify the Monte Carlo simulations. The Monte Carlo results were found to agree within 2% with the measurements performed using film and ionizing chambers in a water phantom. The present EGS4 calculation reveals that the effects of a DW on beam spectral and angular distributions, as well as electron contamination, are much less significant than those for a PW. For the 6 MV photon beam, a 45 degrees PW can result in a 30% increase in mean photon energy due to the effect of beam hardening. It can also introduce a 5% dose reduction in the build-up region due to the reduction of contaminated electrons by the PW. Neither this mean-energy increase nor such dose reduction is found for a DW. Compared to a DW, a PW alters the photon-beam spectrum significantly. The dosimetric differences between a DW and a PW are significant and clearly affect the clinical use of these beams. The data presented may be useful for DW commissioning.

Electrons↗

PubMed1999

Open-wedge osteotomy by hemicallotasis or the closed-wedge technique for osteoarthritis of the knee. A randomised study of 50 operations.

We describe the results of 50 operations carried out on 46 patients with medial osteoarthritis of the knee of Ahlbäck grade 1 to 3. Patients were randomised either to a closed-wedge high tibial osteotomy (HTO) or an open-wedge procedure based on the hemicallotasis technique (HCO). Their median age was 55 years (38 to 68). The preoperative median hip-knee-ankle (HKA) angle was 171 degrees (164 to 176) in the HTO group and 173 degrees (165 to 179) in the HCO group. After six weeks, the median HKA angle was 185 degrees (176 to 194) in the HTO group and 184 degrees (181 to 188) in the HCO group. In the HTO group, seven patients were within the range of 182 degrees to 186 degrees compared with 21 in the HCO group (p < 0.001). One year later, ten HTO patients were within this range while the HKA angulation in the HCO group was unchanged. At two years the numbers were 11 and 18, respectively. We evaluated the clinical results on the Hospital for Special Surgery, Lysholm and Wallgren-Tegner activity scores, and patients completed part of the Nottingham Health Profile questionnaire. An impartial observer at the two-year follow-up concluded that all scores had improved, but found no clinical differences between the groups.

Adult↗

PubMedDate not supplied

Transcuneiform and opening wedge medial cuneiform osteotomy with closing wedge cuboid osteotomy in relapsed clubfoot.

Ten patients (13 feet) aged 4 to 11 years with idiopathic clubfeet underwent bony correction for resistant supination and adduction deformities. A closing wedge cuboid osteotomy and medial cuneiform opening wedge and transcuneiform osteotomy were performed in all cases. The average improvement in anteroposterior talo-first metatarsal angle of 22 degrees, calcaneo-fifth metatarsal angle of 13 degrees, and lateral calcaneo-first metatarsal of 9 degrees confirmed the clinically satisfactory correction in all feet. However, one foot required repeat surgery 2 years after the index procedure.

Child↗

PubMed1988

Organelle distribution in the wedge-, spindle- and inverted wedge-shaped neuroepithelial cells during chick embryo neurulation.

The formation of the neural tube is a morphogenetic process involving cell-shape changes. The activity of the cytoskeletal elements of the neuroepithelial cells and the interkinetic nuclear migration affect the neuroepithelial cell shape in a way that these cells acquire three distinct conformations of wedge-shaped, spindle-shaped and inverted wedge-shaped cells. Each of them is ultrastructurally characterized in this paper with regard to the intracellular distribution of mitochondria, rough endoplasmic reticulum, yolk droplets, lipid bodies and Golgi apparatus. These distribution patterns are analyzed in relation to the role played by the neuroepithelial cells during the successive phases of neural tube formation.

Animals↗

PubMed1994

Comparison of Adhesion Formation in Open Wedge Resection (OWR) With Microsurgical Wedge Resection (MWR)

In 21 patients with polycystic ovarian disease, a laparotomy ovarian wedge resection was performed on both ovaries. The vessels were coagulated with a mini-bipolar instrument. Then, randomly one ovary was left open and the other closed with Vicryl material (5-0 in the interior and 8-0 on the edge of the ovary). Six weeks later, during a second look laparoscopy, the ovaries were scored according to adhesion formation (AFS classification). The mean score of adhesion in the two groups was 52/21 MWR and 82/21 OWR. The mean and standard error for the differences of scores were 1.43 and 0.94, respectively, which were not significant. Contrary to the previous report (Am J Obstet Gynecol; 163:1674, 1990), our study in humans does not show that the OWR is superior to MWR.

Journal Article↗

PubMed1968