General Session: Lumbar
Presented by: R. Garcia - View Audio/Video Presentation (Members Only)
R. Garcia(1), J. Yue(2), L. Miller(3), Yue
(1) Orthopedic Care Center, Aventura, FL, United States
(2) Yale University School of Medicine, Orthopedic Surgery, New Haven, CT, United States
(3) Miller Scientific Consulting, Ashville, NC, United States
Purpose: To compare segmental range of motion (ROM) 2 years following lumbar total disc replacement (TDR) with a mobile core disc (MCD) or a constrained core disc (CCD) implant.
Methods: This post hoc analysis of a multicenter, prospective, randomized, controlled, investigational device exemption trial included patients with symptomatic lumbar degenerative disc disease treated with a MCD(n=183) or CCD (n=48) TDR implant who had available pre-treatment and 2-year imaging studies. Range of motion at the index level (L4-L5 or L5-S1) was assessed withflexion/extension lateral radiographs of the spine. Radiographic success was defined as maintenance or improvement in ROM at the index level. The association of segmental ROM with baseline characteristics and clinical outcomes was also investigated.
Results: Patients treated with MCD had higher rates of radiographic success compared to CCD (59% vs. 44%, p=0.04). Segmental ROM increased from 6.2° to 7.1° through 2 years with MCD, but decreased with CCD (5.9° to 4.8°). Thechange in ROM over 2 years was significantly different between groups (p=0.01), favoring MCD. Improvements in ROM were consistently greater with MCD vs. CCD regardless of age, gender, body mass index, previous lumbar surgery, index level, and preoperative back pain severity. SegmentalROM ≥6° was the best discriminator of clinical outcome at 2 years. Patients who maintained at least 6° segmental ROM at 2 years had greater relative reductions in back pain severity (80% vs. 67%, p< 0.01) and Oswestry Disability Index (73% vs. 61%, p< 0.01) vs. patients with less than 6° segmental ROM. A greater percentage of patients maintained at least 6°segmental ROM with MCD vs. CCD (52% vs. 31%, p=0.01) at 2 years.
Conclusions: Lumbar TDR with a MCD implant yields greater improvements in segmental ROM compared to a CCD implant, regardless of patient characteristics. Maintenance of at least 6° segmental ROM following lumbar TDR is associated with better clinical outcome.