Forearm interosseous membrane trauma: MRI diagnostic criteria and injury patterns

Objective: Define criteria for interosseous membrane (IOM) injury diagnosis using MRI, and characterize patterns of IOM disruption following forearm trauma. Our hypothesis is that most IOM injuries occur along the ulnar insertion, and MRI should be obtained following forearm trauma to assess IOM competency. Design: Sixteen cadaver forearms were subjected to longitudinal impact trauma. Prior to and following injury, MR images were examined by a board-certified musculoskeletal radiologist using pre-defined criteria for determining IOM integrity. Each specimen was dissected and the viability/pattern of injury examined. The MRI and dissection results were compared using a double-blinded methodology. Results: Eight of the 16 specimens demonstrated IOM trauma. Seven specimens demonstrated complete IOM disruption from the ulnar insertion, and one revealed a mid-substance tear with intact origin and insertion. The dorsal oblique bundle was disrupted in four specimens. MRI analysis identified IOM injury in seven of the eight forearms. The injury location was correctly identified in six specimens when compared to dissection observations. MRI determination of IOM injury demonstrated a positive predictive value of 100%, a negative predictive value of 89%, a sensitivity of 87.5% and a specificity of 100%. Conclusion: Our findings demonstrate the accuracy of MRI in identifying IOM disruption, and its ability to localize specific injuries in a clinically relevant model of forearm trauma. The injury patterns demonstrated most lesions occurred along the IOM's ulnar insertion, and in half of the injured specimens there was concomitant dorsal oblique bundle disruption.