Lumbar total disc replacement (TDR) is an alternative treatment to avoid fusion related adverse events, specifically adjacent segment disease. New generation of elastomeric non-articulating devices have been developed to more effectively replicate the shock absorption and flexural stiffness of native disc. This study reports 5 years clinical and radiographic outcomes, range of motion and position of the center of rotation after a viscoelastic TDR. This prospective observational cohort study included 61 consecutive patients with monosegmental TDR. We selected patients with intermediate functional activity according to Baecke score. Hybrid constructs had been excluded. Only cases with complete clinical and radiological follow-up at 3, 6, 12, 24 and 60 months were included. Mean age at the time of surgery was 42.8 +7.7 years-old (27–60) and mean BMI was 24.2 kg/m² +3.4 (18–33). TDR level was L5-S1 in 39 cases and L4-L5 in 22 cases. The clinical evaluation was based on Visual Analog Scale (VAS) for pain, Oswestry Disability Index (ODI) score, Short Form-36 (SF36) including physical component summary (PCS) and mental component summary (MCS) and General Health Questionnaire GHQ28. The radiological outcomes were range of motion and position of the center of rotation at the index and the adjacent levels and the adjacent disc height changes.INTRODUCTION
Material and methods
The viscoelastic cervical disk prosthesis CP-ESP is an innovative one-piece deformable but cohesive interbody spacer. It is an evolution of the LP-ESP lumbar disk implanted since 2006. The implant provides 6 full degrees of freedom including shock absorption. The design allows a limitation for rotation and translation with resistance to motion (elastic return property) aimed at avoiding overload of the posterior facets. The rotation center can vary freely during motion. It thus differs substantially from current prostheses. This study reports the clinical results of a prospective observational study series of 89 patients who are representative of the current use of the ESP implant since 2012. The radiological results are focused on the evolution of the mean center of rotation (MCR) as an additional information to the range of motion (ROM) for the evaluation of the quality of spine movement. 89 patients (33 males, mean age 45 years [28–60], 107 implants) were included for an open, prospective and non-randomized study between October 2012 and December 2015. One level patients were at C3C4 (3), C4C5 (3), C5C6 (41) C6C7 (24) C7T1 (1) Two levels patients were C4C5/C5C6 (3), C5C6/C6C7 (12), C6C7/C7D1 (1) and 3 levels C4C5/C5C6/C6C7 (1)Introduction
Materials and Methods
