Knee+

Knee+ is a stereotaxic navigation system for primary total knee replacement surgery. It includes intraoperative software, surgical instruments, and smart glasses (head-mounted display) to assist surgeons in determining and positioning cutting guides relative to anatomical landmarks and computed mechanical axis. The smart glasses display guidance information and must be used alongside traditional surgical methods, not as a sole navigation tool.

Key modifications from predicate K233899 include: mechanical resection level measurement capability; redesigned orientation mechanism and cutting guide adaptor with new material and anodization; voice command input as optional alternative to button selection; optional connectivity module integration; enhanced user profile and associated surgical data features; redesigned visual interface; reduced hip center acquisition constraint from 10 to 5 acquisitions; and compatibility with new surgical helmet/hoods (K200493 Stryker T7) replacing previous reference equipment.

ASTM F2554 (repeatability and accuracy); IEC 62366-1 (human factors and usability engineering); IEC 62304 (software verification and validation); SAL 10 (cleaning and sterilization of reusable instruments per AAMI ST98 and AAMI TIR12); ISO 17664-1 (reprocessing guidance); ISO 10993 series (biocompatibility including cytotoxicity, sensitization, pyrogenicity, acute systemic toxicity, and irritation).

Knee+ is substantially equivalent to K233899 because it maintains identical indications for use, intended use, and clinical performance for primary total knee replacement guidance. Non-clinical testing demonstrated that the modifications do not raise new safety or effectiveness concerns—precision and accuracy remain unchanged compared to the predicate when measured by the same methods. All design changes were assessed through risk management and design controls, and performance testing confirmed the device functions safely and effectively for its intended use without introducing new risks.