An analysis of pubis symphysis misalignment using plain film radiography.

OBJECTIVE

To show, using a laboratory model, the inherent problems and test the validity of viewing actual pubis symphysis misalignment via plain film radiography in humans.

STUDY DESIGN

In vitro experiment of pubic bone and pubis symphysis model alignment as determined through projected imaging with collimated light.

RESULTS

The shadows cast by plastic models did not accurately reflect the physical reality. The image representations of the pubic bones with significant misalignment appeared as "normal." Some of the misalignments were viewed in the exact opposite alignment on the projected image as compared with the physical reality.

CONCLUSIONS

This study provides evidence that misalignment of the pubic bones cannot be reliably viewed on a standard anteroposterior lumbopelvic radiograph. The results show the potential for missed diagnoses of clinical significance. Additional research on pelvic joint dysfunction and imaging problems is needed.