A Morphologic Analysis of Thumb Ulnar Collateral Ligament Avulsion Fracture Fragments and Risk Factors for Surgical Treatment

Abstract

Background:

There is debate regarding nonoperative versus surgical treatment of thumb ulnar collateral ligament (UCL) tears with avulsion fractures. The aim of this study was to evaluate the fragment size in relation to the UCL footprint size in patients with an avulsion fracture injury and to find risk factors associated with surgical treatment.

Methods:

In a cohort of avulsion fracture injury patients, the largest side of the fragment was divided by the average reported UCL footprint size (ff-ratio), and a logistic regression was performed to find variables associated with surgery.

Results:

The mean ff-ratio was 1.1 in 114 patients with an avulsion fracture injury. Metacarpophalangeal (MCP) joint instability, rather than the largest fragment side, was a significant risk factor for surgery.

Conclusions:

An avulsion fracture fragment associated with thumb UCL injury approximates the dimensions of the UCL footprint. In addition, MCP joint instability was associated with surgery in patients with avulsion fracture injuries.