Shape and function of the diaphysis of the human tibia.

There is an agreement about the principle that bones are optimized to resist daily loads. This has never been ascertained for the human tibia. One of the main load components in the tibia in vivo is a cantilever load (with a linearly varying bending moment, with its largest component in the sagittal plane). investigated if the cross-section of the diaphysis and its variation along the tibia make it an optimized structure with respect to such loads. Six cadaveric tibias were CT-scanned. The geometry and material properties were extracted from the CT-scans, and analyzed along the tibias. A linear variation along the tibia was found for the second moments of area and inertia, and the section modulus in the sagittal plane (slightly less linear in the frontal plane). Conversely, the other properties (polar moments and cross-section are) were much less linear. This suggests that the structure is optimized to resist a bending moment that varies linearly along the tibia. The tibias were instrumented with 28 triaxial straingauges each. Strain was measured under cantilever loading in the sagittal and frontal planes, under quasi-constant-bending in the sagittal and frontal planes, under torsional loading, and with an axial force. The strain distribution was remarkably uniform when cantilever loading was applied in the sagittal plane and slightly less uniform when cantilever loading was applied in the frontal plane. Strain variations were one order of magnitude larger for all other loading configurations. This shows that the tibia is a uniform-stress structure (i.e. optimized) for cantilever loading.

Compliance with mandated emergency contraception in New Mexico emergency departments.

OBJECTIVE: New Mexico enacted a law in 2003 requiring that emergency departments (EDs) offer emergency contraception (EC) to survivors of sexual assault and that both doses be administered in the ED. This investigation sought to examine practices and knowledge of ED providers about EC in the setting of sexual assault. METHODS: We visited hospitals in New Mexico from July 2005 to December 2005 and administered an 18-item questionnaire to three providers-a physician, a nurse, and a clerk-in the ED. The questionnaire included items related to characteristics of the hospital, knowledge of providers about EC and the law, and ED practices relevant to EC for sexual assault survivors as well as for women who had consensual unprotected intercourse. RESULTS: Surveys were completed at 33 of 38 hospitals (87%). Overall, 52% of respondents reported that EC was routinely offered to sexual assault survivors, and 33% reported that both doses were administered in the ED. Forty-one percent of RNs, MDs, and clerks reported that EC was offered to sexual assault survivors who were minors regardless of age. Overall, 64% of respondents knew that EC may prevent pregnancy up to 72 hours after unprotected intercourse, and only 12% of respondents reported awareness of any requirements to offer EC to sexual assault survivors. Respondents reported that physicians in the ED more often routinely offered EC to sexual assault survivors (52%) than to women who requested it after consensual sex (20%). Thirty-three percent of respondents indicated parental consent was necessary for minors in the setting of sexual assault, although there is no requirement for parental notification in New Mexico. CONCLUSIONS: EDs in New Mexico are not universally complying with the law. Better dissemination of the law and education about EC could improve care of sexual assault survivors in New Mexico.