Isthmic lesions involve the pars and can be further broken down into 3 subtypes: stress fractures of the pars, elongated pars defects without fracture, and acute, traumatic pars fractures.

• 峡性脊椎前移涉及椎体峡部，可进一步分为三个亚类：峡部应力骨折；峡部拉长，没有骨折；急性、创伤性峡部骨折。