Background: Continuous stretching is an effective treatment for contractures, and its efficacy can be improved with a dynamic orthosis. Dynamic orthotic positioning is expected to achieve greater clinical results in joints with less pretreatment stiffness and in those with a short window between injury and treatment. Here we studied the effect of dynamic orthotic positioning on the metacarpophalangeal (MCP) joint using computed tomography (CT).

Methods: The MCP joints of 10 human index fingers were examined using CT in healthy subjects who wore flexion- or traction-type orthoses versus those who wore no orthoses.

Results: The palmar joint distance between the traction-type and no orthosis group was not significantly different; however, the distance was shorter with the flexion-type than the traction-type orthosis ( p < 0.05). Compared to healthy subjects without orthoses, the palmar joint space decreased in patients with flexion-type orthoses ( p < 0.05) and increased in healthy subjects with traction-type orthoses ( p < 0.05).

Conclusions: The traction-type dynamic orthosis was designed to correct flexion while achieving joint traction to enhance MCP joint area spacing and minimize damage caused by articular surface collision. Our findings show that the traction-type dynamic orthosis causes joint space widening and may reduce the risk of articular surface collision compared with the flexion-type orthosis.