Long-term outcome of patients suffering from clinical instability after microsurgical treatment of lumbar disc herniation.

A total of 39 patients suffering from clinical instability of the lumbar spine after microdiscectomy were evaluated for their long-term outcome. Included there were 21 (54%) male and 18 (46%) female patients with a mean age of 55 years. All had been operated on for a virgin single-level lumbar disc herniation between the years 1985-1989 and they were evaluated for the presence of lumbar instability in 1991. Clinical signs and symptoms of segmental instability were then detected in all patients, with the symptom of "apprehension" positive in 30. During the follow-up, 2 (5%) patients had been treated by lumbar spondylodesis. At the time of the present investigation, both of them gave the information that their low back pain and sciatica had diminished as compared to the prediscectomy situation; both were retired. The symptom of "apprehension" was negative in both. Of the remaining 37 patients, low back pain had completely recovered in 4 (11%) and diminished in 23 (62%) patients, while in 9 (24%) patients, back pain had remained unchanged and become worse in 1 (3%). Further, sciatica had completely recovered in 4 (11%) and diminished in 23 (62%) patients, while in 7 (19%) patients, sciatica had remained unchanged and become worse in 3 (8%). Only 14 (38%) of these patients were able to work. However, evaluated by the Oswestry Index, the overall outcome in daily activities had significantly improved in all 37 patients since 1991 (p = 0.01). The symptom of "apprehension" was now positive in 26 patients. A significant correlation was observed between the positivity of this test and the persistence of low back pain (p = 0.02) and a poor outcome in daily activities (p < 0.0001). Comfirming earlier observations, the findings of this study support the concept that patients with postoperative lumbar instability have a poor prognosis. Further studies are needed to define the optimal treatment for this problematic patient group.