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Radiographs for the Thumb Basal Joint


- Roberts View:
    - true AP view described by Roberts:
    - take AP view of thumb w/ forearm in maximal pronation & dorsum of thumb resting on the x-ray cassette;

- True Lateral of CMC:
    - obtained w/ forearm flat on table, hand pronated approx 20 deg w/thumb flat on cassette, & x-ray tube angled 10 deg from vertical in distal to proximal projection;
    - allows evaluation of metacarpal displacement;
           - estimates of the size and position of the volar fragment
           - estimates gap between fragment & metacarpal base;
    - Case Example:
           - 20-year-old male who sustained extra-articular basal frx of thumb;
           - on AP and Oblique views the displacement is not impressive;
           - on a true lateral view, however, the indication for surgery is apparent