How to predict requisite nail length in tibial fractures

In a retrospective study involving 59 patients, a regression equation between nail length and body weight has been computed as follows: nail length = -5.05729 + 0.222 x body height (probability value for intercept P = 0.24327 and slope P = 0.0000). Graphic analysis of the residuals gave a randomly scattered blob of data points. Validation of the equation in 12 patients showed an average difference between actual and derived nail length of -0.09 (SD 0.93, minimum -1.57, maximum 1.42). It can be stated that in most cases of intramedullary tibial nailing, the length of nail required can be predicted by the regression equation using the available manufactured nail of the size nearest in length to the derived length or the next size up or down.