Background: MRI has been shown to be highly accurate in assessing collateral ligament injuries of the metacarpophalangeal joint (MPJ) of the thumb. The purpose of this study is to evaluate the accuracy of MRI for diagnosing collateral ligament tears of the MPJ of the fingers. Our hypothesis is that MRI would accurately detect complete tears of collateral ligaments of the lesser digit MPJs.
Methods: We retrospectively evaluated 22 digits in 20 patients undergoing finger MPJ collateral ligament repair. All patients had preoperative MRI scans. The findings on preoperative imaging studies were compared to the intraoperative findings.
Results: All patients had surgically confirmed complete tears of the collateral ligament in question. In 8 of 22 MRI scans (36 %), the preoperative imaging study was inaccurate. Of these eight patients, MRI was interpreted as no tear in one and a partial tear in seven. The sensitivity of MRI for diagnosing a complete tear was 64 %. In all three digits in which 3-T MRI scanning was utilized and documented, the preoperative imaging results did not correlate with the intraoperative findings.
Conclusions: Although MRI can be considered a useful adjunct to evaluating patients with collateral ligament injuries of the fingers, the sensitivity is poor and the imaging results can underestimate the extent of injury. In light of this, the emphasis for determining appropriate course of treatment remains on history and mechanism of injury, physical examination, and patient disability.
Keywords: Collateral ligament injury; Lesser digit MCP joint; MRI.