Failure of the interlocking bones to open

The absence of movement of bone preventing childbirth. The meaning of the term depends on the interpretation given to the interlocking bones.

1. Taking the interlocking bones to be the two parts of what modern medicine calls the pubis, the ancients believed that they were normally closed, but would open to allow child delivery. They also believed that poor nutrition in pregnancy, causing original qì vacuity and preventing qì and blood from reaching the area, could account for their failure to open.
2. Taking the interlocking bones to mean the sacrococcygeal joint, failure of the interlocking bones to open means the failure of the sacrococcygeal joint to move the lower opening of the pelvis to facilitate delivery. This can be treated with Bone-Opening Powder (开骨散 kāi gǔ sǎn).