In vivo trapeziometacarpal joint kinematics using an optoelectronic system: a data basis on healthy subjects

Trapeziometacarpal joint is important concerning thumb function. However, this deep joint is clinically difficult to assess. The purpose of our study is to evaluate the range-of-motion of trapeziometacarpal joint with an in vivo kinematics protocol. One hundred and fifteen hands have been studied in 73 healthy subjects, (twenty-two females and fifty-one males). The mean age was 23.1 years old. (Range, 22 to 35 years). An optoelectronic device (Polaris®) was used to analyse thumb range-of-motion. Splints were used to evaluate the isolate trapeziometacarpal joint. Retroreflective markers were placed on the splints and thumb. Anatomical landmarks were pointed to localize bone segment. Three patterns of range-of-motion were assessed. Guides were used to improve movement repeatability. The protocol has been feasible in all subjects. The mean measurement time was 15 minutes. Mean flexion-extension and abduction-adduction was respectively 53 and 42 degrees without guides, 68 and 48 degrees with guides. The mean axial rotation of the thumb was 27 degrees. The mean distance between axes of each movement was 7 millimetres. We developed a data basis of trapeziometacarpal joint range-of-motion in vivo measures, to our knowledge, which have not been previously proposed. Comparison with literature shows range-of motion is similar to short in vivo series or in vitro studies. However, distance between axes of flexion-extension and abduction-adduction is more important in our study. Moreover, thumb axial rotation occurs in abduction-adduction movement, which has not been previously described.