Here are seven other cases of hyper mobility. You will learn about another radiologic sign: the misalignment of the coccygeal vertebrae (also called "bones") in the sitting position, which is an accompanying sign of hyper mobility in flexion, and you will see two examples of a frequent difficulty in reading the radiographs, when the distal part of the coccyx is involved.

Case #7. Hyper mobility can also be accompanied by another interesting sign: a misalignment of the two involved bones (a step in their anterior aspect) which is obvious in this case, where the two other radiologic signs are present : hyper mobility (40°) and bony contact with friction.

Case #8. The mobility is between 25° and 30°, but there is a friction of the bones and a misalignment in flexion, which I consider abnormal (despite very slight here). Naturally, the interspace was tender at palpation.

Case #9. Another example of misalignment in flexion (X).

Case #10. A misleading aspect. The distal bone, not clearly visible on the sitting film here, has pivoted of 50° in flexion. The patient felt her pain at the tip of the coccyx, a vey good clinical indicator.

Case #11. Another case with hyper mobility and friction (note on the sitting film how the opposite surfaces are congruent) but without misalignment.

Case #12. this case is similar to case #9, the distal part of the coccyx being difficult to evidence on the film.

Case #13. A strange aspect. There is clearly an hyper mobility, but the coccyx seems to be in a permanent state of anterior luxation.

Case #14. This is a "sitting film" with a marked misalignment and an irregularity of the endplate, with a step, maybe corresponding to the sacral apex.