A PROSPECTIVE SERIES OF DYNESYS FLEXIBLE STABILISATION IN THE MANAGEMENT OF LOWER BACK PAIN: 2 TO 5 YEAR RESULTS

Abstract

Introduction Dynesys flexible stabilisation was developed by Giles Dubois in 1992, and first used in 1994 (1). Our unit has undertaken 375 operations to date. We report a consecutive series of 200 patients who underwent Dynesys flexible stabilisation in the management of intractable lower back pain.

Methods Access to our spinal service is exclusively from a back assessment centre run by a triaging nurse practitioner who works closely with the senior author. Conservative treatment is arranged by the centre, and includes physiotherapy to the point of failure. Patients were only accepted for the study if exhaustive conservative management had failed. They underwent operation by the senior author between September 2000 and March 2003. Patients were divided into two groups: Group 1 – Cases where implantation was used as an adjunct to other procedures including decompression, discectomy, or posterior lumbar interbody fusion. (32 male, 36 female, Mean age 56years (range 31–85)) Group 2 – Patients with back pain and/or sciatica in which no other procedure was used. (65 male 67 female, Mean age 58years (range 27–86)) All patients were profiled prospectively using the Oswestry Disability Index (ODI), SF36 and Visual Analogue Scale (VAS). Patients were reviewed post-operatively using the same measures at 3, 6 and 12 months, and yearly thereafter. Follow-up was 95% at 2 to 5 years.

Results Group 1 – Mean ODI fell from 54 pre-op to 24 at four years. Mean SF36 improved from 43 pre-op to 56 at four years Group 2 – Mean ODI fell from 49 pre-op to 28 at four years. Mean SF36 improved from 40 pre-op to 62 at four years. Similar trends were observed in both groups at five years with these favourable scores tending back towards pre-operative levels. Screw failures, either loosening or fracture, occurred at a rate of 15% over the follow-up period.

Discussion Our results support the use of flexible stabilisation as an alternative to spinal fusion. There is currently no consensus on absolute indications for the procedure however. Such indications can only be defined following clinical outcome. Perceived indications were based on contemporary understanding of the biomechanical effects of the construct. Further investigation of these variables is clearly desirable. Screw failures (15%) have detracted from the overall success, although the relationship between such failures and poor outcomes is complex and difficult to elucidate at the current time. The virtue of flexible stabilisation over fusion includes avoidance of domino effect, reversibility and possible healing of a painful segment. The key issue is whether flexible stabilisation is as effective and this requires prospective randomised controlled investigation, both against fusion, and against conservative management. We feel our results in this difficult group of patients are reasonable and continue to use it in our practice.