NextStep Arthropedix Total Knee System

The NextStep Arthropedix Total Knee System is a cemented total knee replacement device indicated for pain relief and improved knee function in skeletally mature patients with severe knee pain due to osteoarthritis, rheumatoid arthritis, traumatic arthritis, and related conditions. It includes two system options: Posterior Stabilized/Cruciate Retaining/Ultra Congruent configurations, and a new Medial Pivot system with cruciate retaining and cruciate substituting variants.

The device uses identical CoCr alloy femoral components (ASTM F75) and Ti-6Al-4V tibial bases (ASTM F136) to the predicate. Tibial inserts are manufactured from cross-linked UHMWPE (same as predicate) or vitamin-E blended cross-linked UHMWPE (ASTM F648). Patellar components are now manufactured exclusively from vitamin-E blended cross-linked UHMWPE. The subject device differs by offering additional CR/PS femoral component sizes, additional vitamin E UHMWPE material options for tibial inserts, and a new Medial Pivot system option.

Not stated in this summary. The document references 'consensus standards' and 'published literature' but does not cite specific ISO, IEC, or ASTM standards for the testing performed.

Substantial equivalence is established through identical materials and manufacturing to the predicate device (CoCr, Ti-6Al-4V), same intended use and indications, similar principles of operation, and comparable size ranges. The new vitamin E UHMWPE material conforms to ASTM F648 (same standard as reference device K202022), and comprehensive nonclinical verification testing confirmed fatigue performance, constraint, wear, and mechanical properties met all acceptance criteria relative to predicate and literature values. The additional component sizes and new Medial Pivot option represent incremental design variations rather than fundamental technological changes affecting safety or effectiveness.