LUMBAR TOTAL DISC REPLACEMENT AND NON-OPERATIVE CARE: A LONGITUDINAL COMPARISON OF TWO CONCURRENT COHORTS WITH A MINIMUM FOLLOW-UP OF TWO-YEARS

Abstract

Introduction: Lumbar Total Disc Replacement (TDR) is an accepted treatment for recalcitrant Chronic Discogenic Low Back Pain. However, no studies have compared Lumbar TDR to non-operative intervention. The aim of this study was to investigate the two-year outcomes for con-current cohorts of chronic discogenic low back pain patients undergoing either Lumbar TDR or novel non-operative care.

Methods: Data for the TDR cohort was from prospectively collected data of patients who had undergone Prodisc II lumbar TDR during August 2003 to December 2005. Two-year data for the non-operative cohort was collected prospectively from 880 sequential patients who underwent non-operative intervention between January to December 2005 and who met the inclusion and exclusion criteria. Inclusion criteria: age > 20 and < 65, single/two level disc disease, low back pain > 6 months, had failed non-operative intervention. Exclusion criteria were: previous lumbar surgery, listhesis, facet disease, osteoporosis, pregnancy, red flag conditions, or poor command of English. Additional non-operative inclusion criteria were: attended a minimum of 3 non-operative sessions, completed the entry questionnaire. Novel non-operative care consisted of a cognition-driven motor relearning intervention, aimed at altering provocative movements and postures and reintegrating these alterations into daily life. Manual therapy and spinal injections were used as an adjunct where needed. Pre-treatment and two-year follow-up data for the following outcomes were collated from a modified NASS questionnaire: back/leg pain, activity limitation, and global perceived improvement. Data was expressed as mean difference with 95% confidence intervals for the difference between the means. Student-t test and paired student-t test were used to assess between group and within group differences.

Results: 16 patients (9 males) were identified in the lumbar TDR cohort with median age 43 years (29–57) and median duration of symptoms of 3.5 years (0.5–24). 16 patients (9 males) were also identified in the non-operative cohort with median age of 42 years (24–61) and median duration of symptoms of 2.5 years (0.5–24). There were no cross-overs, however one patient in the TDR cohort had previously undergone the non-operative care regime. There were no significant pre-treatment differences observed in age, sex, duration of symptoms and back pain intensity between cohorts. However, significant pre-treatment differences were observed with 25% greater leg pain and 25% greater activity limitation score in the TDR cohort when compared to the non-operative cohort. Following Lumbar TDR the mean differences at two years for back pain, leg pain and activity limitation favoured improvements of 3.6(2 to 5.1) and 3.4(1.8 to 4.9) and 30.5%(19.2–41.8) respectively when compared to pre-treatment. Similar improvements were observed for the non-operative cohort with 5.0(3.7–6.3), 2.8 (0.7–5.0) and 20.9%(9.4–32.4) for back pain, leg pain and activity limitation respectively. 71% of Lumbar TDR patients and 67% of Non-operative patients reported their relief of symptoms as exceeding 60% at the two-year follow-up.

Discussion: The data suggests that prior to treatment, patients undergoing lumbar TDR were worse off in activity limitation and leg pain than the non-operative cohort. However, improvements in back pain, leg pain, and activity limitation are clinically significant at two-year follow-up with either Prodisc II-L TDR or novel non-operative care for chronic discogenic low back pain patients. Clinically, it may be reasonable to offer patients with lesser leg pain intensity and activity limitation ongoing non-operative care. This level 3 evidence needs to be supported with more case cohorts or an otherwise ethically difficult to conduct RCT.