Table 1.

MRI Grading System for Stress Fractures of the Pars Interarticularis⁹

Grade	Description	MRI Features
0	Normal	Normal marrow signal Intact cortical margins
1	Stress reaction	Marrow edema Intact cortical margins
2	Incomplete fracture	Marrow edema Cortical fracture incompletely extends through pars
3	Complete active fracture	Marrow edema Fracture completely extends through pars
4	Fracture nonunion	No marrow edema Fracture completely extends through pars