Spondylolisthesis describes the anterior displacement of a vertebra or the vertebral column in relation to the vertebrae below. It was first described in 1782 by Belgian obstetrician, Dr. Herbinaux. He reported a bony prominence anterior to the sacrum that obstructed the vagina of a small number of patients. The term “spondylolisthesis” was coined in 1854, from the Greek “spondyl” for vertebrae and “olisthesis” for slip. The variant “listhesis” is sometimes applied in conjunction with scoliosis. These “slips” occur most commonly in the lumbar spine.
X-ray picture of a grade 1 isthmic spondylolisthesis at L4-5
A hangman’s fracture is a specific type of spondylolisthesis where the C1 vertebra is displaced anteriorly relative to the C2 vertebra due to fractures of the C2 vertebra’s pedicles.
The most common grading system for spondylolisthesis is the Meyerding grading system for severity of slip. The system categorizes severity based upon measurements on lateral X-ray of the distance from the posterior edge of the superior vertebral body to the posterior edge of the adjacent inferior vertebral body. This distance is then reported as a percentage of the total superior vertebral body length:
Grade 1 is 0–25%
Grade 2 is 25–50%
Grade 3 is 50–75%
Grade 4 is 75–100%
Over 100% is Spondyloptosis, when the vertebra completely falls off the supporting vertabra.