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- Discussion:
    - based on the assessment of stability;
    - lesions are graded as Type I, Type II, or Type III depending on degree of instability;
    - Bucholz noted that on postmortem dissection of pts w/ pelvic fractures that all injuries to pelvic ring had some injury to both anterior and posterior portions of the pelvis;
    - Type I:
         - injuries for which the roentgenograms reveal only anterior rami frxs demonstrated at least hemorrhage & partial disruption of posterior SI ligaments;
    - Type II:
         - lesion is similar to the AP compression lesion;
         - it is characterized by the presence of anterior instability and partial posterior instability.
    - Type III:
         - lesion demonstrates complete anterior and posterior instability;
         - it may be due to vertical shear, Lateral Compression, or complex mechanism of injury;
         - instability is secondary to both the bony and the ligamentous disruption of pelvic ring;
         - degree of ligamentous disruption is a key to stability because fracture alone will not produce instability without associated displacement and ligamentous disruption