Distinctive features of pathologic vs. normal digitalised femoral head x-ray images: Importance of vertical and horizontal patterns characteristics

Objectives: Determination of possibilities to detect illnesses by subsequent processing of digital radiograms of healthy and sick femoral heads. Study Design: From 120 conventional X-rays of hip joint, 27 undoubtedly health and 62 undoubtedly sick femoral heads X- rays were picked out. Central parts of heads were digitalized, 300 points per inch, into a 256 x 256 pixel matrix. Each matrix was split to four 128 x 128 squares. Two groups of methods were applied separately to horizontal rows and to vertical columns: variance coefficient, power coefficient of Fourier harmonics series of 128 pixels Results: In variance coefficient analysis of long series (256 pixels) presentations of sick femurs are characterised by increase variability. In short vertical segments (128 pixels), sick heads show lower variance coefficients which means that pathology of femoral head deletes fine variability in vertical series and superimposes a coarse pattern to it demonstrated only as increased variability of series of 256 pixels. It is in conformity with results of Fourier analysis: in sick femoral heads column harmonics show increased coarse patterns of large wave length from 20 to approx. 1 mm with simultaneous decrease of fine pattern of rows with wave length of about 0.2 mm. Conclusion: Aside from applied methods, valuable information on disease of femoral head were obtained mainly from data on vertical series of pixels, while the same data from horizontal rows were inefficient in detection of disease. It indicates that advanced degenerative process of femoral head changes its X- ray in specific way, mainly in vertical direction. It seems waranted to verify these methods as tools for detetection and staging of the femoral head degeneration in a prospective study.