We sought to clarify the capability of routine magnetic resonance (MR)
imaging of the knee to detect and grade tibial collateral ligament (T
CL) injury. We also wanted to define the exact MR findings that were t
he most important for diagnosis. Sixty-three patients were clinically
evaluated for TCL injury prior to MR imaging of the knee on a 1.5-tesl
a system. MR studies were scored with respect to multiple direct and i
ndirect findings. By discriminant analysis, the overall accuracy of cl
assification (into clinical grades 1, 2, 3 and normal) on the basis of
MR was 65%. Accuracy for detection of abnormal TCLs was 87%. The most
useful MR findings for detection and grading of TCL injury were direc
t signs: subcutaneous edema over the TCL, focal disruption of the TCL,
increased signal in the TCL on T2-weighted images, and longitudinal s
triations within the TCL. Indirect signs such as trabecular trauma wer
e less useful for TCL evaluation. The presence of a tear of the anteri
or cruciate ligament, however, correlated with TCL injury of a higher
grade. T2-weighted coronal images, by better depicting intraligamentou
s edema and fiber disruption, improved the MR assessment of the TCL.