Tendon Laceration by Pressurized Water
Surgeons from the University of Michigan report an isolated case of a tendon in the hand being cut by a stream of water from a pressure washer. In this case, a 43-year-old man suffered a tendon injury of the thumb from the force of a high-pressure water spray.

He was using a home unit pressure washer to clean the outside of his house. As he was coming down the ladder, the spray wand directed the stream of water across his left hand. The thin stream of water with a pressure of 2300 psi made a cut across the base of his thumb.

The extensor pollicis longus tendon was sliced in half by the spray. Water was forced up into his forearm through the opening in his skin. Surgery was needed to repair the tendon. The surgeon reported a clean cut of the tendon. A branch of the radial nerve was also cut.

This case shows the power of home unit pressure washers. Likewise, industrial water guns can put out a stream of water strong enough to cause serious injuries. The mechanical action and the force of the spray is enough to puncture the skin and cut a tendon.

The authors suggest with the increased home use of power equipment like pressure washers, there will likely be more injuries expected.
References
John C. Austin, MD, and Fred M. Hankin, MD. High-Pressure Water Injection Causing an Isolated Tendon Laceration: A Case Report. In The American Journal of Orthopedics. April 2007. Vol. 36. No. 4. Pp. 213-214.