The Range of Movement of the Thumb

Abstract

Purpose The movements at each thumb joint are flexion and extension (called radial abduction in the CMCJ) and additional movements of anteposition, retroposition and opposition at the CMCJ, due to the saddle shape of the articulation. Our study was designed to provide a means of thumb movement measurement and provide a range for each. Methods A prospective cohort study was performed looking at 100 consecutive individuals without thumb pathology to determine thumb joint range of movements and evaluate the reliability of such measurements. Results The mean age was 26 (range of 18–37) with 62 female individuals. The mean range of movement of the IPJ was flexion of 88 ° (80–90 °) and extension of 12° (0–45°). That of the MCPJ was flexion of 60° (43–70°) and extension of 8.1° (0–15°). That of the CMCJ was anteposition of 61.2° (50–71°), retroposition of 31.1 mm (25–38 mm), radial abduction of 62.9° (53–71°), opposition Kapandji grade 9 (grades 9–10) and adduction of 10.2 ± 4°(5–20°). CMC adduction was difficult to measure with a poor intra- and inter-observer correlation (inter-reliability correlation coefficient of 0.02 and intra-reliability coefficient of 0.04). For the remaining measurements, the mean inter-reliability correlation coefficient was 0.82 ( p<0.01) while the mean intra-reliability correlation coefficient was 0.93 ( p<0.01). There was negative correlation identified between IPJ extension and MCPJ extension (−0.50) and between CMCJ radial abduction and MCPJ extension (−0.60). Conclusions Having established the normal ranges of movements for the thumb joints and shown that our measurement methods are reliable and reproducible, we have identified that a reduction in certain thumb joint movements appears to be compensated for by an increased movement range in the other joints.