Lightning Podiums: Smorgasboard - Room 802B

Presented by: J. Bourget-Murray

Author(s):

J. Bourget-Murray(1), G. Hardy St-Pierre(2), K. Gurr(2), J. Bouchard(1)

(1) University of Calgary, Calgary, AB, Canada
(2) University of Western Ontario, London, ON, Canada

Abstract

Introduction: Modern lumbar total disc replacement (TDR) has been used in clinical practice for over 20 years. However, limited long-term clinical data from North America exists outside of large US Food and Drug Administration (FDA) investigational device exemption (IDE) studies. Short-term clinical results following lumbar TDR have been reported, yet few have shown its therapeutic effectiveness beyond 2 years. This study examines the long-term results of lumbar TDR by comparing two datasets in Calgary and London, Canada. We aim to determine the value of lumbar TDR in patients with low back pain, with a minimum 5-year follow-up. We anticipate similar outcomes following lumbar TDR comparable to the large FDA studies, as well as comparable functional improvements between patients from Calgary and London.

Methods: All patients who underwent a single-level lumbar TDR with a minimum 5 years follow-up by a single surgeon in Calgary or London were included in the study. We retrospectively collected 23 variables pertaining to patient demographics and patient-reported outcomes prior to index surgery. By phone follow-up, we prospectively collected data in order to assess degree of disability and quality of life following surgery using a visual analog scale (VAS) for low back pain and leg pain, Oswestry disability index (ODI), and need for reoperation. We analyzed one primary endpoint: a composite indicator of clinical outcomes, complications and reoperation. Secondary endpoints included improvement in VAS Leg, VAS Back and ODI at final follow-up. A multivariate analysis via Logistical regression of all 23 collected variables was conducted. The two datasets were compared for clinical variables and outcomes via T-test.

Results: We had 79 patients to review in Calgary. Fifty seven percent had excellent results defined as >50% improvement in both VAS and ODI as well as no complications or reoperation. We compared these results to 61 patients in London: 59% had excellent results. Average follow-up was 8.3 years and 8.7 years for patients in Calgary and London, respectively. The best convergent model revealed 2 variables associated with prediction of an excellent outcome: clinical pain duration (OR 2.39 p = 0.01) and narcotic use (OR 0.01 p = 0.05). At final follow-up, average VAS back was 3.05, 3.00 (pre-op: 7.8, 7.9), VAS leg was 1.79, 2.67 (6.0, 5.9) and ODI was 21.3, 18.7 (57, 52), in Calgary and London respectively.

Discussion: This study demonstrates that success rates comparable to the large US FDA studies are achievable in clinical practice. It also confirms positive long-term results are sustained beyond the 2 years mark. In this context, the loose consensus among the spine surgery community that back pain is not amenable to surgical intervention is brought into question. This study has shown that with strict selection criteria, as in Calgary and London, lumbar TDR provides long term surgical relief of back pain on a sustained basis. Further research to elucidate this selection framework is needed.