Comparative analysis of morphologival parameters in isolated and fused L5 spondylolysis patients on the basis of CT features

Differences in the sagittal morphological parameters of the pedicles and vertebral bodies can be observed between the two types of spondylolysis patients. In the isolated spondylolysis pattern, the pedicles exhibit a "thin, long, and contracted" morphology, while the vertebral bodies present a "stuffed bun" shape, both anteriorly, posteriorly, and superiorly. In contrast, the fused type is characterized by "short, thick, and expanded" pedicles, with the vertebral bodies showing a "less pronounced stuffed bun" shape in the anterior-posterior direction. These morphological differences indicate that spondylolysis separation may involve adaptive stress-induced bone remodeling. Surgeons must pay special attention when choosing surgical techniques, as isolated spondylolysis may present a tendency toward slippage. Caution is advised in performing isolated pars repair surgeries, especially during the placement of pedicle screws, where special attention must be given to the length and direction of the screws to avoid additional damage.