A traumatic cause (not pars) of a spondylolisthesis is which Wiltse classification?

• A. Type 1
• B. Type 5
• C. Type 3
• D. Type 4

Answer: (D)

Wiltse’s system for spondylolisthesis includes five categories: dysplastic (congenital), isthmic (pars interarticularis defect), degenerative, traumatic, and pathologic. When the slip arises from an acute injury to the posterior elements that is not due to a pars interarticularis defect, it falls into the traumatic category. This is why the answer is the traumatic type. The other categories cover congenital misdevelopment, pars fractures, degenerative facet changes, and bone pathology, respectively.