PubMed Health⌕ Search

Biomedical subjects

M Krag

Publications and source records attributed to M Krag.

7 recordsLinked to original sources
PubMed1992

Human lumbar vertebrae. Quantitative three-dimensional anatomy.

This study details the quantitative three-dimensional surface anatomy of human lumbar vertebrae based on a study of 60 vertebrae. The two lower vertebrae (L4 and L5) appeared to be transitional toward the sacral region, whereas the upper two vertebrae (L1 and L2) were transitional toward the thoracic region. Means and standard errors of the means for linear, angular, and area dimensions of vertebral bodies, spinal canal, pedicle, pars interarticularis, spinous and transverse processes were obtained for all lumbar vertebrae. This information provides a better understanding of the spine, and allows for a more precise clinical diagnosis and surgical management of spinal problems. The information is also necessary for constructing accurate mathematical models of the human spine.

Cadaver↗
PubMed1992

External fixator pin design.

The integrity of the bone-pin interface is the critical link in the stability of external fixation systems. External fixation pins placed in cancellous metaphyseal bone frequently loosen over time, resulting in fixation failure and an increased risk of infection. To design an external fixation pin with optimal bone-metal interface strength in cancellous bone, a systematic study of various thread design features was performed. Combinations of pitch, tooth profile, and minor diameter in 5 mm self-tapping half pins were evaluated in coaxial pullout testing using a fresh bovine cancellous bone. A significant increase in pullout strength was found with a decrease in minor diameter. No statistical differences were found in pullout strength attributable to thread profile and pitch. There were no significant interactions between minor diameter and tooth profile or minor diameter and pitch. The data obtained suggest significantly greater holding power in cancellous bone can be achieved by using an external fixation pin with a smaller minor diameter or a larger interference. Additional pullout testing of five commercially available external fixator pins was performed. Of these, the two pins with the largest interference demonstrated greater pullout strength. Therefore, within a range of acceptable major diameters and adequate minor diameters for the torsional strength requirements, an optimal interference for cancellous pin application may exist and it may well be larger than that present in currently available external fixation pins.

Animals↗
PubMed1991

Thoracic human vertebrae. Quantitative three-dimensional anatomy.

This study details the quantitative three-dimensional surface anatomy of thoracic vertebrae based on a study of 144 vertebrae. The thoracic spine was found to have three distinct regions: upper, middle, and lower segments. The two end segments appear to be transitional zones toward cervical and lumbar regions. The middle zone (T3 to T9) is of utmost importance due to the presence of the combination of narrow spinal canal and critical vascular supply. Means and standard errors of the means for linear, angular, and area dimensions of vertebral bodies, spinal canal, pedicle, pars articularis, spinous and transverse processes, and rib articulations are provided for all thoracic vertebrae. This information is necessary for constructing accurate mathematical models of the human spine. It will also provide a better understanding of the spine, and allow for a more precise clinical and surgical management of spinal problems.

Anthropometry↗
PubMed1985

Biomechanical time-tolerance of fresh cadaveric human spine specimens.

Changes in the biomechanical properties of fresh cadaveric spinal specimens due to long-term freeze storage and long test periods have been investigated. Fresh cadaveric specimens were divided into three groups: Group A specimens were tested fresh on the 1st day and 13 subsequent days; Group B specimens were tested on the 1st day, frozen in sealed bags at -18 degrees C for 21 days, and tested for 13 consecutive days after thawing; and Group C specimens were frozen for up to 232 days and tested for 14 consecutive days after thawing. We could not find any significant differences between the behavior of the three test groups. This implies that freezing and storage, even for long periods, do not significantly alter the physical properties of cadaveric spinal specimens. Concerning the differences observed on a daily basis, the mean value of the maximum displacement for the 1st day did not differ significantly from the corresponding mean value for the 13 consecutive days. This was true for all three groups, although there was some indication that the fresh group specimens showed greater variation than the two frozen groups.

Adult↗
PubMed1985

Lumbar paraspinal compartment syndrome. A case report with physiologic and anatomic studies.

A 24-year-old man presented with severe low-back pain and paraspinal muscle spasm after exertion. Elevation in temperature, white blood cell count, serum muscle enzymes, and urine myoglobin, as well as computer tomographic evidence of paraspinal muscle edema and necrosis, were present. No etiology could be documented, and the possibility of an acute exertional compartment syndrome was entertained. Subsequently, cadaveric dis-sections indicated that the erector spinae muscles are contained within a well-developed fascial sheath. Continuous slit catheter pressure measurements within this compartment in eight healthy male subjects were subsequently carried out. These indicated a physiologic behavior similar to other known compartments for which compartment syndromes have been described. Variation in intracompartmental pressure occurred as a function of body posture, erector spinae isometric contraction, and active intra-abdominal pressurization. We suggest this patient had a paraspinal compartment syndrome and have described pressure characteristics of this compartment in normal men.

Adult↗
PubMed1983

Gower's sign.

Explore the source record for details and available documents.

Child↗