A review of the pathomechanism of forward slippage in pediatric spondylolysis: The Tokushima theory of growth plate slippage

Abstract

Spondylolysis is a stress fracture of the pars interarticularis, which in some cases progresses to spondylolisthesis (forward slippage of the vertebral body). This slip progression is prevalent in children and occurs very rarely after spinal maturation. The pathomechanism and predilection for children remains controversial despite considerable clinical and basic research into the disorder over the last three decades. Here we review the pathomechanism of spondylolytic spondylolisthesis in children and adolescents, and specifically the Tokushima theory of growth plate slippage developed from our extensive research findings. Clinically, we have observed the slippage site near the growth plate on MRI; then, using fresh cadaveric spines, we found the weakest link against forward shear loading was the growth plate. We subsequently developed an immature rat model showing forward slippage after growth plate injury. Moreover, finite element analysis of the pediatric spine clearly showed increased mechanical stress at the growth plate in the spondylolytic pediatric spine model compared with the intact pediatric spine. Thus, spondylolysis progresses to spondylolisthesis (forward slippage) in children and adolescents with the growth plate as the site of the slippage. Repetitive mechanical loading on to the growth plate may serve to separate the growth plate and subsequently progress to spondylolisthesis.

Vertebrae, Vertebral End Plates, and Disks: Concepts and Specific Pathologies

“…The slippage takes place at the intervertebral disk and is caused by degeneration of the disk. 52 Thus on radiographs, CT, and MRI, the important difference between the pediatric and the adult slippage is the deformity of the vertebral plate, as seen in pediatric patients, in which the vertebral body commonly has a wedge-like shape after slippage occurs (►Fig. 6a).…”

“…6b). 52 Moreover, the pars interarticularis of the vertebra do not tend to fracture due to slippage in patients with degenerative disk disease; therefore the finding is termed pseudospondylolithesis.…”

Phenotypic characterization of Slc26a2 mutant mice reveals a multifactorial etiology of spondylolysis

“…Around 70% of the patients with bilateral defects in the L5 isthmus showed progression to spondylolisthesis, characterized by the forward slippage of a vertebra relative to an adjacent one and associated with back pain . Though various clinical features, radiographic findings, and relevant diseases have been reported as risk factors of spondylolysis, the pathogenesis of lumbar spondylolysis still remains unclear …”

“…7 Though various clinical features, radiographic findings, and relevant diseases have been reported as risk factors of spondylolysis, the pathogenesis of lumbar spondylolysis still remains unclear. [8][9][10][11][12] For many years, there has been a debate over relative contributions of developmental isthmic defects and mechanical trauma to pars lysis. Spondylolysis might be a result of repetitive microfractures.…”

Mild (not severe) disc degeneration is implicated in the progression of bilateral L5 spondylolysis to spondylolisthesis

“…Abnormal spinopelvic morphology and orientation measured through parameters such as pelvic incidence, sacral slope, pelvic tilt may create a biomechanical environment leading to the development of a pars defect and its progression to spondylolisthesis [ 3 – 6 , 9 ]. In children and adolescents, the progression of the defect to spondylolisthesis is attributed to growth plate injury which may perpetuate to epiphyseal ring separation [ 8 , 10 ]. Slippage in skeletally immature spines is not attributed to any disc degeneration, but rather growth plate lesions [ 7 ].…”