A New Look at Fifth Metatarsal Base Fractures

Fifth metatarsal fractures are traditionally divided into three zones: Zone I (tuberosity avulsions), Zone II (Jones fractures) and Zone III (diaphyseal stress fractures). 

Based on a recent diagnostic study, a new two-part system refines Zone 1 injuries by splitting them into two distinct patterns:

• Avulsion – stable, pulled off by the peroneus brevis tendon

• Indirect – unstable, caused by a bending force that extends beyond the tendon's footprint

Reading the x-rays

The dividing line between the two patterns sits 15 mm from the tuberosity, at the articular surface‘s inflection point. 

What this means for practice

The system scored near-perfect reliability (κ = 0.92) among surgeons using the system. Critically, all four indirect fractures managed without surgery resulted in nonunion – underscoring the system's real clinical stakes.