Developmental balloon disc of the lumbar spine in healthy subjects.

A radiologic analysis of the unusually concave disc-vertebral border with special reference to the balloon disc in the lumbar vertebra was performed in 878 Japanese healthy adolescents and adults. Ninty-one operated patient with lumbar disc herniation with or without balloon disc were also studied. The balloon disc was observed on an average of 14% regardless of age in the healthy population with an obvious male predominance and was most commonly observed in the taller adolescents. The difference between the primary site of the endplate concavity associated with a balloon disc and with a Schmorl's node are evident (P less than 0.01). The characteristics of the balloon disc in the healthy population consist of (1) an age-independent and nonregressive nature, (2) a normal developmental variation, (3) no association with low-back pain and herniated nucleus pulposus.