Lumbar instability and clinical symptoms - Which is the more critical factor for symptoms: Sogittal translation or segment angulation?

Background: The relationship between radiologic instability and its symptoms is controversial. Previous authors consider flexion-extension radiographs to be of little value in evaluating instability; however, the current authors consider the variation of results in evaluating radiologic instability to be the result of limitations in previous researchers' methods. Methods: In this report, sagittal translation and angulation at the L4-L5 segment were measured in flexion-extension films in 1090 outpatients with low back and/or leg pain using a three-landmark measuring method. The symptoms of four groups with and without 3-mm translation and with and without 10degrees angulation were compared for all the patients and for 280 age-matched patients using a scoring system. The age-matched patients were followed up for 4.6 years. Results: Results showed that patients with greater than or equal to3-mm translation had significantly lower scores, indicating a limitation in their daily activities due to pain, than patients <3-mm translation; however, no difference was observed between the groups in terms of angulation. The group with greater than or equal to3-mm translation and greater than or equal to10degrees angulation significantly demonstrated the lowest scores at both evaluations during the initial visit and follow-up. This group had been suffering from low back and/or leg pain the longest and had visited the hospital significantly more often than other groups. Conclusion: In conclusion, translation of the lumbar segment has a greater influence than angulation on lumbar symptoms. The presence of both radiologic factors could be an indicator for persistence of the symptoms.