Rotational-Bearing Total Knee Arthroplasty: Less Than Advertised—Opposes

Conventional first-generation (standard) and second-generation (deep-dish) rotating platforms have stood the test of time since their introduction as revision prostheses in 1978. In long-term (10- to 20-year) studies investigators have documented component survivorship of 95%-100% in both cemented and cementless applications, which compares most favorably to the best fixed-bearing knee replacements currently available. Mechanical problems encountered in the first 3 decades of use include wear and “spin-out,” seen in 1%-2% of cases. Third-generation rotating platforms were successfully developed to minimize these 2 small but formidable problems. An 18-year comparative study of 153 cementless first-generation rotating platforms were compared with 259 third-generation rotating platforms with increased surface congruity and a rotational stop-pin to prevent “spin-out.” No wear or “spin-outs” were seen in the third-generation design, which demonstrated a survivorship of 99.4% compared with a first-generation survivorship of 98.3% when an end point of revision for any mechanical reason was used.