Symptoms in relation to the level of spondylolysis.

Spondylolysis usually occurs in the fifth lumbar vertebra, which with the rest of the lumbosacral junction may be hypoplastic. About 10% of spondylolysis occurs in the fourth lumbar vertebra which is usually normal radiologically. The present work studies the hitherto unknown prognostic value of the lysis level in relation to symptoms. A comparison was made between 213 patients with lysis at L5 and 42 patients with lysis at L4. The frequency and intensity of low back pain, the need for treatment, change of work, sickleave, and sick pension caused by low-back symptoms were noted during a period of more than 20 years. Pain frequency and intensity and functional impairment were consistently higher in the L4 group. The differences were particularly evident between the two subgroups when there was a marked vertebral slip. It is concluded that the level of spondylolysis is of significance in the occurrence of low-back symptoms.