General Session: Cervical Motion Preservation

Presented by: C. Schaetz - View Audio/Video Presentation (Members Only)


L. Gössel(1), C. Schätz(1), K. Ritter-Lang(2)

(1) Orthopädische Klinik Markgröningen, Markgröningen, Germany
(2) Orthopädikum Potsdam, Potsdam, Germany


Introduction: Lumbar total disc replacement surgery is an alternative to fusion for replacement of a degenerated disc in patients experiencing uncontrolled low back pain. Previous clinical studies of lumbar artificial discs have shown at least non-inferiority to lumbar fusion at 2 years postoperative, and more recent publications have indicated sustained clinical outcomes at 5 years. The relative merits of single- vs. multiple-level arthroplasty are not well understood with some investigators reporting inferior outcomes in multiple-level arthroplasty patients while others report no difference. The M6-L Artificial Lumbar Disc (Spinal Kinetics, Inc., Sunnyvale, CA) is an advanced generation intervertebral disc designed to maintain motion of a functional spinal unit by replicating anatomic, physiologic, and biomechanical characteristics of the native disc. This study assesses the clinical outcomes after single-level or multiple-level M6-L total disc replacement at 5-years.

Methods: The purpose of this study is a multi-center, post-market examination of previously implanted M6-L patients includes all patients from two centers who had reported clinical outcomes, both pre-operatively and at an average 5.6 years post-implantation. Clinical assessments included Oswestry Disability Index (ODI) and a back and leg visual analog scale (VAS) pain score. Patients who had been implanted with a single M6-L as well as those who were implanted with multiple M6-L discs were included.

Results: 63 patients (30 males and 33 females) with a mean age of 42 years were implanted with the M6-L and completed their latest follow-up at an average of 5.6 years (range 4.5 to 7.2 years) post-implantation as of June 2016. Thirty five patients (16 male, 19 female) were implanted at a single-level (SL), while 28 patients (14 male, 14 female) were implanted at multiple-levels (ML). The follow-up period and ages of the two cohorts were 5.8 years (SL) and 5.4 years (ML); average ages were 43 (SL) and 41 (ML). Mean ODI scores for the two groups were comparable pre-operatively (means 43 vs. 40, respectively, p > 0.05) as were the VAS back pain scores (6.2 vs. 6.9, p > 0.05), and VAS leg pain score of the preoperative predominant leg (4.9 for each group, p > 0.05). At last follow-up, both groups were significantly improved relative to their baseline on all measures (p < 0.001). The ODI scores had decreased by 25 and 23 points in the SL and ML groups, respectively. Mean VAS back pain scores were 2.6 and 2.5, respectively, and preoperative predominant leg VAS pain was reduced to 2.2 and 1.4, respectively, in the SL and ML groups. There were no statistically significant differences between the groups in the clinical outcomes at last follow-up (p > 0.05).

Conclusions: This is the first study to report clinical and radiographic outcomes of TDR with the M6-L in single-level vs. multiple-level implantations with 5+ years follow-up. The experience of these two centers in a real world setting indicates that the disc performs clinically as intended for the treatment of symptomatic lumbar degenerative disc disease in both single-level and multiple-level disease.