Partial Flexor Tendon Injury Causing Locking: Illustration of the Utility of Dynamic Ultrasound.

Clinical diagnosis of partial flexor tendon lacerations is challenging because tendon function may be preserved. Although some partial flexor tendon tears can be managed conservatively, pain, stiffness, and triggering/locking may result, requiring surgical management. The mechanism by which this occurs has been investigated in animal and cadaver studies but has not been demonstrated in patients with real-time, in vivo imaging. Here, we present a case of partial tendon tear presenting with severe pain and locking that was diagnosed before surgery and characterized with dynamic ultrasound.