General principles of fracture reduction involve axially distracting or pulling on a fracture fragment and pushing the piece back into anatomical alignment. This can be seen in the video below (automatically starts at 2:25 for the actual procedure). What if this approach doesn’t work? The fracture fragment remains immobile despite your best efforts.

Trick of the Trade: Metacarpal Neck Fracture

Jahss reduction technique

This technique, also known as the 90-90 approach (see top diagram), involves flexing the patient’s MCP and PIP 90 degrees. Dorsal force is applied to metacarpal head by through dorsal pressure on the proximal phalanx. The 90-90 positioning also stretches the collateral ligaments of the MCP joint, which further optimizes the reduction technique.

Although this cool animation below was intended for patient education, it nicely illustrates how the Jahss technique works.

Image from AO Foundation
Michelle Lin, MD
ALiEM Founder and CEO
Professor and Digital Innovation Lab Director
Department of Emergency Medicine
University of California, San Francisco
Michelle Lin, MD


Professor of Emerg Med at UCSF-Zuckerberg SF General. ALiEM Founder @aliemteam #PostitPearls at Bio:
Michelle Lin, MD