US patent granted for Signus Rotaio artificial cervical disc

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The US Patent and Trademark Office has granted a patent for the Rotaio artificial cervical disc prosthesis (Signus).

The patent relates to the anatomical prosthesis design, which is capable of resisting the high forces exerted while the patient is moving (e.g. pivoting, torsional, and combined pivoting and torsional motions). Furthermore, the product is designed to allow insertion as a pre-mounted assembly.

This follows the recent publication of a prospective observational study with 24 month follow-up which demonstrates that the Rotaio implant is safe and effective in the treatment of symptomatic degenerative cervical disc disease. The study data confirms Rotaio as an alternative to anterior cervical discectomy and fusion, according to a company release.

In a non-interventional study, 45 patients (aged 18 to 65) were treated with the Rotaio prosthesis. The surgeries were carried out between January 2011 and December 2012 in two centres (University Clinic for Neurosurgery, Innsbruck, Austria and Clinic for Neurosurgery, Munich-Bogenhausen, Germany). Based on standardised questionnaires, various target criteria were collected: neck disability index (NDI), pain intensity in the arm and neck using the visual analogue scale (VAS score) and patient satisfaction index (PSI), as well as the use of pain medication and the overall result. A survey of patients was carried out prior to surgery, directly after the surgery, three to six months after surgery, and one year (28 patients) or two years (17 patients) after surgery. In addition, radiological examinations were carried out.

For all enquired parameters, significant improvement was demonstrated. Thus, NDI improved from 21.6 ± 9.8 prior to implantation to 10.6±8.3 at the second and 10.5±9.3 at the last follow-up examination. The neck VAS score improved significantly from 5.3±2.8 prior to implantation to 2.4±1.8 at the second and 3.3±2.7 at the last follow-up examination. The arm VAS score also improved: from 5.93±3.17 prior to implantation to 1.91±1.81 at the second and 2.88±2.27 at the last follow-up examination.

In addition, the use of pain relievers decreased significantly: 66.7% of patients took pain relievers ‘often’ or ‘always’ prior to implantation. At the last follow-up a significant reduction was observed. 45.8% of the patients rated their use of pain relievers with ‘never‘, 33.3% with ‘seldom‘.

All patients (100%) described their condition as ‘good’, ‘significantly better’ or ‘excellent’ after surgery. This remained until the end of the study period for 44 patients. Only one patient (2.2%) reported a significant deterioration in the last follow-up. The PSI showed that all patients except one would definitely or probably undergo the same treatment.

There were no signs of anterior migration, dislocation or sintering in the radiological accompanying investigations. Furthermore, a significant increase of ROM (range of motion) of 6.3±2.9 degrees prior to implantation to 8.4±2.5 degrees was observed at the first follow-up examination and to 8.6±2.8 degrees during the last examination. The sagittal alignment was well restored in all cases.