Intracranial circulation: pulse-sequence considerations in three- dimensional (volume) MR angiography

The technique and feasibility of magnetic resonance (MR) angiography of intracranial vessels were studied in 35 healthy volunteers. Variations in image orientation, repetition time (TR), and flip angle were evaluated to determine their effects on flow-related enhancement. Gradient modifications--including echo time (TE), motion compensation, bandwidth, and field of view--were also studied in an effort to reduce motion-induced phase shifts. Results indicated that a FISP (fast imaging with steady precession) sequence with a TR of 50 msec, TE of 15 msec, velocity compensation in the read and section-select directions, acceleration compensation in the read direction, anisotropic volume, and a 1.25-mm partition thickness produced three-dimensional angiographic MR images that were accurate and reproducible in the depiction of the major intracranial vessels. Difficulties with field of view, persistent signal void secondary to higher-order motion, and spatial resolution remain major problems requiring additional study.     

The limited contact dynamic compression plate (LC-DCP)

Summary To realize the new concept of biological internal fixation the limited contact dynamic compression plate was developed. It minimizes vascular damage to the plated bone segment. It should lead to a more versatile and efficient application of internal fixation using plates.     

Paediatric dacryocystorhinostomy

Of 258 cases of dacryocystorhinostomy performed on children in the period September 1981 to September 1991, 130 were for simple, unresolved congenital nasolacrimal duct obstruction. Other indications for surgery included punctal agenesis, lacrimal fistula, post-traumatic and post-inflammatory canalicular obstruction. Of 177 children without canalicular pathology, 171 (96%) were relieved of symptoms with one operation, without canalicular intubation. Of 81 cases with canalicular disease, 55 of 70 (79%) who underwent DCR plus canalicular intubation, and 10 of 11 who underwent DCR plus Lester-Jones tube, were substantially improved with one operation. No child required peroperative or postoperative blood transfusion. Dacryocystorhinostomy in childhood, in experienced surgical hands, is a safe procedure, achieving relief of symptoms in most cases, particularly in the absence of canalicular disease.     

Reaming versus non-reaming in medullary nailing: Interference with cortical circulation of the canine tibia

Summary Medullary nails have only been used with reluctance in the treatment of open fractures since reaming interferes with the cortical circulation. The technique of interlocking offers the interesting possibility of inserting a relatively stiff nail which does not necessarily require reaming. The effects of reaming prior to nail insertion upon the cortical circulation was investigated in the canine tibia. Intravital staining with procion red was used to trace areas of disturbed circulation. Nail insertion without reaming provided clear advantages for the bone's blood supply, while reaming disturbed perfusion in two-thirds of the cortical area and regionally extended through the entire thickness of the cortex. The disturbance without reaming was limited to the inner layer of the cortex and involved only one-third of the cortical cross-section.     

Treatment of defects of the long bones using distraction osteogenesis (Ilizarov) and intramedullary nailing. Theoretic principles, animal experiments, clinical relevance

For large shaft defects of tibia and femur, distraction-compression osteosynthesis (Ilizarov) provides an ideal autologous bone graft. Combination of this with an intramedullary interlocking nail instead of an external fixator could improve patient comfort, because transport with a small external device takes only one-third of the total fixation period. Using 21 adult female sheep we created standardized tibia shaft defects 20 mm (medium size) and 45 mm (large size) in length. The tibiae were stabilized with non-reamed intramedullary interlocking nails. Following corticotomy by chisel, segments were transported using subcutaneous traction wires with a screw as a fulcrum to maintain stationary skin exit points without soft tissue problems. The external traction devices were removed after 12 or 16 weeks. Animals were sacrificed after 12 or 24 weeks with medium-size defects, and after 16 or 32 weeks with large defects. We evaluated the results clinically, by standardized weekly X-rays and, after sacrifice, by quantitative computed tomography (QCT). No animals had to be excluded from the study. Despite primary destruction of the intramedullary circulation all distraction gaps were spanned with bone. X-Rays showed typical signs of good quality of distraction bone regeneration (narrow radiolucent zone in the middle of the regenerate, longitudinal structure), continuous calcification, and cortex formation. QCT cross sections showed completely circular bone regeneration with small and large defects. Bone regeneration was faster on the dorsal side, where more bone was formed than ventrally. Small defects can remain ventrally in the regenerate; these close secondarily.(ABSTRACT TRUNCATED AT 250 WORDS)