Clinical outcome 24 months after cervical disc arthroplasty with a new articulating and viscoelastic disc prosthesis.

Background: Various cervical disc prosthesis and implant designs for motion preservation are routinely used in cervical disc arthroplasty (CDA). One of the newest implant designs combines features of an articulating gliding surface with those of a viscoelastic flexible core. This should allow for absorption of compressive loads in the axial direction, whereas the gliding surface at the inner surface is intended to allow a physiological range of motion with a progressive increase of resistance in six degrees of freedom (DOF). The aim of this study was to evaluate the safety and efficacy of a new cervical disc prosthesis in a mono-centric clinical setting. Methods: This observational study analyzes the first clinical and radiological results over a period of up to 24 months and evaluates the safety and efficacy of the novel CDA design. Subjects with one- or two-level degenerative cervical disc disease were enrolled. Radiographic assessments were performed pre-operatively, as well as at the 12- and 24-month follow-ups. Clinical data including pain scores [visual analog scale (VAS), Denis Pain Scale, pharmacological treatment], function scores [Neck Disability Index (NDI), modified Japanese Orthopaedic Association (mJOA)], outcome scores (mMacnab) and complication rates were monitored. Results: Forty-five subjects (21 male/24 female) with a mean age of 43.4 years (30-62 years) were operated on the levels C4/5 (7.0), C5/6 (22.0) and C6/7 (23.0) between 01/2021 and 01/2025. A total of 52 implants with sizes between 5 mm ×16 mm and 8 mm ×18 mm were used. Clinically, all subjects reported significant improvements in pain and functional outcomes; however, VAS arm improved better than VAS neck, whereas NDI and mJOA improved at all time points over baseline. No serious adverse events were monitored. Heterotopic ossification (McAfee grades 3 and 4) was observed in 17.3% after 2 years, subsidence with migration into the endplates >2 mm in 11.5%. There were no re-operations due to mechanical problems or implant malfunction. Conclusions: The clinically tested articulating and viscoelastic design concept demonstrated both safety and effectiveness for the treatment of degenerative cervical disc disease. Compared to baseline, all subjects demonstrated significantly improved quality of life and reduced pain, as well as a decreased need for analgesics.