modulus region of the force elongation curve it is possible to attain information on the collagen structure when the moduli of the high stiffness region of the stress strain curves through a fixed point in various orientations are plotted in polar co ordinates the graph of mechanical properties with respect to testing direction is periodic it is clear from fig1 that these points join to form an ellipse shape 1 these results substantiate the hypothesis that langer 39 s line 5 is the preferred orientation of the fibres within the reticular dermal tissue the results as shown in fig1 demonstrate that the direction of a local langer 39 s line 5 can be positively determined by multiple force elongation tests however obtaining a complete set of load extension curves in many directions is extremely time consuming fig2 shows the effect of limiting the number of such tests in order to minimize the number of tests needed a mathematical procedure may be adopted formulated using only 3 points f 1 f 2 amp f 3 it is hypothesized that the 3 data points will follow an ellipse 10 in order to find the equation of an ellipse that will best fit the 3 data points all the calculations are performed in polar co ordinates and the equation of the ellipse is given as follows the first data point f 1 at 0 u00b0 is taken approximately along the direction of the skin 39 s crease lines which are known to be close to the langer 39 s line and so this magnitude will be larger than f 2 and f 3 therefore it is expected that the major axis of ellipse to lie close to this point and hence the value of 0 is expected to be small.