Motion Analysis of the Trapeziometacarpal Joint Using Three-dimensional Computed Tomography.

Background: Zancolli theorized that the first metacarpal bone axially rotates on the semispheroidal part of the trapezium, which is controlled by ligaments. This study used three-dimensional computed tomography (3D-CT) to describe the motion of the first metacarpal bone on the trapezium.

Methods: 3D-CT images were taken of the left hand of 30 healthy volunteers (mean age [Formula: see text] years, 15 men and 15 women). They were divided into five groups: radial abduction, retroposition, adduction, palmar abduction, and opposition. The range of motion of radial abduction and palmar abduction of the trapeziometacarpal joint was measured from the first metacarpal bone to the second metacarpal bone. The range of motion of pronation was measured following Cheema's method. The main contacts of the joint surface of trapezium and the first metacarpal bone were determined on the 3D-CT images.

Results: Pronation of the trapeziometacarpal joint was [Formula: see text] in radial abduction, [Formula: see text] in retroposition, [Formula: see text] in adduction, [Formula: see text] in palmar abduction, and [Formula: see text] in opposition. Radial abduction was [Formula: see text] in radial abduction, [Formula: see text] in retroposition, [Formula: see text] in adduction, [Formula: see text] in palmar abduction, and [Formula: see text] in opposition. Palmar abduction was [Formula: see text] in radial abduction, [Formula: see text] in retroposition, [Formula: see text] in adduction, [Formula: see text] in palmar abduction, and [Formula: see text] in opposition. The contact surfaces of the trapezium and the first metacarpal bone were dorsal and ulnar in radial abduction, radial and ulnar in retroposition, and volar-ulnar and volarradial in opposition, respectively, while they were both central in adduction and both radial in palmar abduction.

Conclusions: The range of motion of the trapeziometacarpal joint was 44° for radial abduction/adduction, 48° for palmar abduction/adduction, and 57° for pronation/supination. The varying contact surfaces of the trapezium and the first metacarpal bone enabled a wide range of motion.