The bone mineral content (BMC) and cross-sectional properties of cadaveric radii were assessed by single photon absorptiometry (SPA). A new multiple-angle scanning technique was used in conjunction with SPA to measure the area and moments of inertia of the radial cross section in intact forearms. The radii of the same forearms were then broken in a failure test to simulate a fall on the outstretched arm. Colles' fracture was produced in 16 of 18 radii tested. The BMC divided by the bone width, which is called bone mineral density (BMD) in clinical applications, did not correlate with the load at failure in cadaveric forearms. The BMC alone did correlate significantly with failure load (r2 = 0.62), and the cross-sectional properties gave the best correlation with failure load in a sequential multiple regression (r2 = 0.80). We conclude that if SPA is to be used in clinical studies to predict risk of radial fracture or of fractures at remote skeletal sites, then BMC should be used rather than BMD. An even better indicator of radial bone strength than BMC would be a biomechanical parameter derived from the cross-sectional area and moments of inertia, which can be obtained from multiple-angle SPA.
One hundred ten cases of the transient neurological phenomenon, cervical cord neurapraxia (CCN), are presented. The authors established a classification system for CCN, developed a new computerized measurement technique for magnetic resonance (MR) imaging, investigated the relationship of the cervical cord to the canal, and analyzed clinical, x-ray, and MR data. One hundred nine males and one female were included in the study; the average age of the participants was 21 years (range 13-33 years). All episodes occurred during sports participation; 87% occurred while the patient was playing football. Follow-up review lasting an average of 3.3 years was available for 105 patients (95%).Narrowing of the sagittal diameter of the cervical canal in the adult spine was confirmed to be a causative factor. Cervical cord neurapraxia was not associated with permanent neurological injury and no permanent morbidity occurred in patients who returned to contact activities. Of the patients returning to contact activities, 35 (56%) experienced a recurrent episode. The risk of recurrence was increased with smaller spinal canal/vertebral body ratio (p < 0.05), smaller disc-level canal diameter (p < 0.05), and less space available for the cord (p < 0.05). There was no correlation between either the classification of the CCN episode or the disease noted on MR imaging and x-ray films and the risk of recurrence.The authors conclude that: 1) CCN is a transient neurological phenomenon and individuals with uncomplicated CCN may be permitted to return to their previous activity without an increased risk of permanent neurological injury; 2) congenital or degenerative narrowing of the sagittal diameter of the cervical canal is a causative factor; 3) the overall recurrence rate after return to play is 56%; and 4) the risk of recurrence is strongly and inversely correlated with sagittal canal diameter and it is useful in the prediction of future episodes of CCN (p < 0.001). These data will enable the physician to counsel individuals regarding a predicted risk of recurrence based on canal measurements.
The morphology of bone may be influenced by many factors, including electromechanical ones such as electric potentials, electric fields, or zeta potentials. Stress-generated potential studies in bone and particle electrophoresis studies using calcium-deficient hydroxyapatite have shown that the zeta potential depends on the composition of the steeping fluid and steeping time. To better quantify and understand these in situ potential changes in bovine cortical bone, the effects of alterations in calcium, phosphate, and fluoride concentrations in Neuman's Fluid (NF), which simulates in vivo bone extracellular fluid, were investigated using particle electrophoresis. The zeta potential increased in magnitude with increased calcium concentration in NF in as little as 17 min. Increasing phosphate concentration in NF also increased the zeta potential magnitude. These results provide support for a structural model of the bone matrix surface-bone fluid interface, which incorporates the bone surface proper (composed of collagen, mineral, and boundary regions), stationary layer (in which ions, ionic complexes, and proteins may be adsorbed), and bone extracellular fluid. These results, coupled with those of previous studies, indicate that the protein phase probably has an important role in the determination of the physiologic zeta potential; the role of the mineral phase may also be important.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.