ARTIFICIAL DISC REPLACEMENT - PRELIMINARY-REPORT WITH A 3-YEAR MINIMUM FOLLOW-UP

Artificial disc replacement was performed in six patients with an aver age age of 55 years and average follow-up of 3.4 years. Four of the si x patients had juxtafusion degeneration, one had multilevel disc degen eration, and one patient had isolated disc resorption. The Acroflex di sc (Acromed Corporation, Cleveland, OH), which was used in the replace ment, is composed of a rubber core vulcanized to two titanium end plat es. The latter have superior posts to provide for initial mechanical f ixation and porous in-growth surfaces for long-term fixation. Satisfac tory results occurred in four of six patients. Poor results occurred i n the presence of deformity that resulted in prosthetic failure and is olated disc resorption. There was an average 8-degrees angular and 2.3 -mm translational movement and satisfactory in-growth at all interface s. Design objectives of endurance, biocompatability, geometry, kinemat ics, constraint, dynamics, stability, and fail-safe were met; however, this study is preliminary in nature.