Two types of laminolysis in adolescent athletes

Abstract

Bony defects in the spine are divided into three main types: spondylolysis, pediculolysis, and laminolysis. Lumbar spondylolysis is a well-known stress fracture that occurs frequently in adolescent athletes. Pediculolysis means stress fracture of the pedicle, which sometimes occurs subsequent to unilateral spondylolysis. Laminolysis is a rarely reported stress fracture similar to spondylolysis and pediculolysis that sometimes causes low back pain (LBP). However, its pathomechanism has not been elucidated. Recently, we encountered four adolescent athletes with symptomatic laminolysis. Mean age was 15.8 (range 15-17) years. All subjects reported severe LBP exacerbated by extension of the lumbar spine, and radiology revealed two types of laminolysis: hemilaminar type and intralaminar type. To elucidate the mechanisms of each type, we reviewed a biomechanical study, and found that the hemilaminar type was thought to be subsequent to contralateral spondylolysis, while the intralaminar type might be a result of a stress fracture due to repetitive extension loading.

Fig. 1

Left panel: lateral plain X-ray shows a defect in the L5 lamina. Right panel: CT images show two fracture lines. One is seen in the right pars interarticularis (spondylolysis), and the other is seen in the left lamina (laminolysis)

Fig. 2

CT images show a pars defect (spondylolysis) on the right side and laminolysis on the left side

Fig. 3

a CT images show a clear defect in the L5 lamina, which is seen intralaminally. b MRI shows signal changes along the fracture line with high intensity on a fat-saturated T2-weighted image

Fig. 4

a CT images show a bony defect intralaminally. b MRI shows signal changes along the defect with high intensity on a fat-saturated T2-weighted image