basic criteria, i.e. clinical finding and correlating finding of an imaging method, while conservative treatment fails, indicates that this procedure does not provide despite very accurate modern imaging possibilities and differentiated surgical techniques the corresponding effects. Even despite the increasing number of operations made possible among others by the perfection of imaging methods their relative success is declining. Supplementation of these three main criteria by several factors which beyond doubt influence the prognosis of surgery, increases the safety when indicating surgery and reduces their number in an appropriate way. Multivariant stepwise regression analysis identified among them nine of the most important proteinorrhachias, the number of severe attacks of disease, their type, index of severity, mental condition, somatotype, laterality of complai nts and in employed people the period of work incapacity. These compressed logistic formulas can be used as the fourth supplementary criterium for recommending surgery in addition to the three main criteria if the value of the calculated risk of failure of surgery does not exceed 10 %. Then real surgical advances can be achieved, not only improvement, in as many as 90% patients. Calculation of the logistic formula is easy and by means of tables of coefficients and vectors of 7Œ9 predictive factors, as the doctor works simply with these constants of factors and uses an ordinary calculator equipped with an exponential function whereby he proceeds from thedenominator of the formula. In addition to a correct procedure of calculation it is important in this indication technique to respect carefully three main indication criteria and assess and evaluate carefully each of the 7-9 predictive factors on which depends the construction of the final fourth supplementary indication criterium.

        Key words: predictive factors, logistic formula, fourth indication criterium