A long-term effect of distal radius fracture on the sensorimotor control of the wrist joint in older adults.

INTRODUCTION: Sensorimotor control can be disturbed because of pain and trauma. There is scarce comprehension about which component of the sensorimotor system would benefit the most from treatment in distal radius fracture (DRF). PURPOSE OF THE STUDY: The purpose of this study was to determine whether the sensorimotor control of subjects with a history of DRF impaired compared with healthy subjects. If so, which component of the sensorimotor system is most affected. METHODS: Nine healthy participants and 11 participants with a DRF history executed posture and reproduction tasks in interaction with a robotic wrist manipulator. A posture task with force perturbations assess sensorimotor control. Position and force reproduction tasks assessed sensory feedback. Electromyography recorded the muscle activity to study the motor part of the sensorimotor system. STUDY DESIGN: Cross-sectional case-control. RESULTS: The results showed that the motor responses to the perturbations during the posture task did not differ significantly, whereas the position reproduction did significantly differ between the 2 groups. Moreover, participants with a DRF history did not adapt to the changed dynamics of the environment during the posture task, whereas the controls did. DISCUSSION: The results of this study imply that processing of sensory position feedback is impaired in people with a DRF history while sensorimotor control during a posture task is unaffected. A possible explanation for these results is that different neural networks are involved during reproduction and posture tasks. CONCLUSIONS: A history of DRF is related to disturbed processing of sensory feedback of the sensorimotor system, especially the Joint Position Sense, which leads to an impairment in detecting a changed environment and adapting to it. Impaired Joint Position Sense and thereby the inability to adapt adequately to a changing environment should be taken into account during the rehabilitation of patients with DRF.