Towards understanding knee joint laxity: errors in non-invasive assessment of joint rotation can be corrected.

The in vivo quantification of rotational laxity of the knee joint is of importance for monitoring changes in joint stability or the outcome of therapies. While invasive assessments have been used to study rotational laxity, non-invasive methods are attractive particularly for assessing young cohorts. This study aimed to determine the conditions under which tibio-femoral rotational laxity can be assessed reliably and accurately in a non-invasive manner.

Incidence of calcaneal apophysitis in the general population.

Background: Calcaneal apophysitis, or Sever's disease, is a traction apophysitis. It is a frequent cause of heel pain in children. Knowledge about the exact incidence of calcaneal apophysitis in the general population, however, is lacking.

Characteristics of gonads and oviducts in hatchlings and young of Chelydra serpentina resulting from three incubation temperatures.

Eggs of Chelydra serpentina were incubated at 30 degrees C and 26 degrees C. In addition, incubation was done at 20 degree C during the temperature-sensitive period for sex determination. Incubation at 20 degrees C and 30 degrees C resulted in females; incubation at 26 degrees C resulted in males in 99% of the cases.

Temperature levels and periods of sex determination during incubation of eggs of Chelydra serpentina.

Eggs of Chelydra serpentina were shifted during incubation between the female producing temperatures of 20°C or 30°C and the male producing temperature of 26°C. In the 20°C and 26°C combination, the stages during which incubation temperature determined sex were stage 14 through stage 16 (stages of normal series, Yntema, '68). In the 30°C and 26°C combination, the temperature sensitive stages for sex determination were stage 14 through stage 19.

Effects of incubation temperatures on sexual differentiation in the turtle, Chelydra serpentina.

Eggs of the common snapping turtle, Chelydra serpentina, were incubated at constant temperatures ranging from 20°C to 30°C, At hatching, the oviducts were absent or incomplete in males; the testes were differentiated. In females at hatching, the oviduct was intact hut in some cases the gonad retained bisexual characteristics. Three months after hatching, the ovary was differentiated and contained follicles.