Dynamic imaging and wrist biomechanics: a narrative review.

Abstract

The wrist is a complex joint with tightly coupled intercarpal kinematics that remain difficult to interpret clinically. Traditional models, derived from static imaging and cadaveric studies, treat the wrist as a three-dimensional structure. However, wrist biomechanics is inherently dynamic, emerging from interactions across motion phases, loading conditions and functional tasks. Current limitations contribute to under-recognition of clinically relevant instability. This narrative review summarizes representative studies from the past 10-15 years, with emphasis on <i>in vivo</i> dynamic imaging studies reporting quantitative kinematic outcomes. Four modalities (4D-CT, biplanar videoradiography, four-dimensional magnetic resonance imaging and motion capture) were evaluated in terms of kinematic findings and clinical utility, with findings organized by substructure. Dynamic imaging demonstrates that wrist kinematics are phase-, load- and task-dependent. Abnormalities such as scapholunate instability may only become apparent during specific phases of motion or under physiological loading. 4D-CT currently provides the most accessible <i>in vivo</i> assessment of intercarpal coordination, while biplanar videoradiography offers high-precision kinematic analysis in controlled settings. Motion capture characterizes task-dependent wrist motion for functional activities but lacks intercarpal resolution, whereas four-dimensional magnetic resonance imaging offers potential for integrating soft-tissue behaviour, although current applications remain limited. Dynamic imaging shows that wrist instability arises from abnormal motion patterns rather than a static structural abnormality. Rather than competing, these modalities provide complementary, structure-specific insights. This framework supports clinical interpretation of wrist instability and guides appropriate technique selection. However, clinical interpretation will require further standardized protocols and clinically validated thresholds.