List four other radiographic findings that may be seen.

1. Heberden's and Bouchard's nodes in the hands
2. Deformity and malalignment secondary to joint space collapse and injury to the capsular ligaments (e.g., varus or valgus deformity of the knees)
3. Subchondral collapse
4. Vacuum disc sign (i.e., gas in the spinal apophyseal joints and intervertebral discs)