Navigation-Assisted and Robotic Total Hip, Knee, and Unicompartmental Arthroplasty: Reconciling Positioning Accuracy with Biomaterial Performance and Long-Term Implant Survival

Navigation-assisted and robotic systems improve component positioning in total hip (THA), total knee (TKA), and unicompartmental knee arthroplasty (UKA), but whether this improves biomaterial performance and implant survival is unclear. This structured narrative review asks for which bearing materials and fixation interfaces positioning accuracy plausibly alters the degradation and fixation pathways that govern survival, and how strong the evidence is for each link. We propose a conceptual model linking positioning to the local mechanical environment, material-specific degradation, biological response, and survival, and grade each link’s evidence by study design. Enabling technologies consistently reduce outliers. Position-dependent degradation is well documented for conventional polyethylene, ceramic-on-ceramic, and metal-on-metal bearings, mainly from simulator, retrieval, and cohort studies. Highly cross-linked polyethylene appears to attenuate the wear penalty of malposition, although rim fatigue and impingement remain position-sensitive and vitamin E stabilization has no proven additional clinical benefit. In cementless TKA, varus alignment is associated with greater early tibial migration, a validated surrogate for loosening. Clinical translation remains limited: trials and registries show no consistent reduction in all-cause revision after TKA or THA, with lower dislocation after THA and a more favorable UKA signal as exceptions. Precision may matter most for position-sensitive bearings and cementless interfaces.