Abstract:

Objectives:The present study was undertaken to measure the angle of humeral torsion (AHT) on digital images. The aimsof the present study were to estimate the: i) angle of humeral torsion, ii) difference in the AHT between right and left humeri,and iii) reliability of the method. Methods: A total of 185 unpaired humeri (101 right and 84 left) from South India of unknown age and sex available at thedepartment of anatomy were studied. Reference points for the long axis of the upper end of the humerus were marked. Anend-on digital photograph of the articular surface of the head was taken. Using appropriate software, lines were drawn todefine the AHT. Printouts of the above images were taken and the AHT measured with a protractor. The mean and standard deviation of the AHT were calculated for all the humeri and separately for each side. The unpaired t-test was used todetermine the significance of the side differences. Inter- and intra-observer reliability was estimated using the technical errorof measurement (TEM), relative technical error of measurement (rTEM) and coefficient of reliability (R).Results: The mean AHT considering all the humeri was 59.65°±10.97. The corresponding values on the right and left sidewere 57.85°±9.80 and 61.83°±11.93 respectively, with a significantly greater (p=0.02) mean AHT on the left side.Acceptable rTEM values of 4.27% and 7.62% for intra-observer and inter-observer repeat measurements were obtained. Conclusion:The mean values of the AHT lie within the range previously described, with significantly greater values on theleft side. The method described showed acceptable inter- and intra-observer reliability

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