Range of Motion Exercise for Thumb MP Joint Contracture

Background: The range of motion (ROM) of the thumb MP joint varaies widely among individuals. Thus, comparison with the normal side is essential in ROM exercises for thumb MP joint. The purpose of this study was to define the difference between right and left ROM of the thumb MP joint in the normal population and to assess the utility of the normal side value as a normal indicator. Methods: Three hundred hands of 150 subjects (75 men, 75 women; average age, 36.2 years, range 20-49 years of age) without a history of injuries or diseases of the thumb were included. The flexion and extension were measured with a goniometer at intervals of 1 degrees. Statistical analysis of flexion angle, extension angle, differences between men and women, and differences between right and left were carried out. Results: The average flexion was 59.1 degrees (16 degrees-90 degrees). The average extension was 7.9 degrees (-32 degrees-58 degrees). Both the flexion and extension were greater in women than in men. The average difference between right and left was 4.8 degrees (0 degrees-28 degrees) for flexion and that was 6.4 degrees (0 degrees-38 degrees) for extension. For a p-value of 0.05, the one-sided 100pth percentile of the flexion was 10.6 degrees and that of the extension was 14.3 degrees. For a p-value of 0.01, the one-sided 100pth percentile of flexion was 15.1 degrees and that of the extension was 20.1 degrees. Conclusions: The difference between the maximum flexion of and the minimum flexion was 74 degrees. The difference between the maximum extension and the minimum extension was 90 degrees. Due to these large differences, it appeared that some angles could not be determined as normal. In contrast, the average differences between right and left for flexion and extension were small enough to be considered as normal indicators. The one-sided 100pth percentile results showed that flexion loss of more than 11 degrees and extension loss of more than 15 degrees were suspicious for contracture, and that flexion loss of more than 16 degrees and extension loss of more than 21 degrees strongly suggested contracture.