Imageless navigation in unicompartmental and total knee arthroplasty: Systematic evidence on alignment, kinematics, and outcomes

Abstract

Objective: To assess the clinical efficacy and surgical precision of unicompartmental (UKA) and total knee arthroplasty (TKA) performed using navigation systems, comparing outcomes with conventional instrumentation and contemporary robotic platforms. Methodology: A PRISMA-compliant systematic review was conducted across PubMed, ScienceDirect, and Google Scholar (January 2010-October 2025), using Boolean combinations targeting knee arthroplasty, computer-assisted/navigation technologies, robotics, and Amplivision/Amplitude systems. Eligible studies included clinical trials, prospective and retrospective cohorts, experimental accuracy studies, and human case reports. Exclusion criteria comprised reviews, editorials, nonclinical cadaveric or animal studies, and inaccessible full texts. Two independent reviewers performed screening, data extraction, and bias assessment using RoB-2 and NOS tools, resolving discrepancies by consensus. Primary endpoints included distributional alignment (HKA; component orientation in coronal, sagittal, and axial planes; outliers at ±2-3°), soft-tissue balance surrogates, early recovery metrics (pain, length of stay), complications, patient-reported outcomes (PROMs), and revision rates. Results: From 312 records, 124 full texts were reviewed, and 59 studies were included. Amplivision-specific findings encompassed complex UKA-to-TKA conversions with restoration of mechanical axis and joint line, a 447-case routine TKA cohort (≈47% using Amplivision) with no mid-term mechanical loosening or dislocation, and a dual-centre trochlear-guided program achieving CT-validated femoral rotational alignment, preserved rectangular flexion gaps, and elimination of internal-rotation outliers. Across randomized and comparative studies, computer navigation consistently reduced coronal outliers and narrowed alignment dispersion compared to conventional jigs. Registry data linked navigation to lower revision risk in patients under 65 years, likely due to suppression of extreme malalignment under higher activity exposure. Robotic systems (MAKO, ROSA, NAVIO/CORI) further reduced plan-to-implant error and enhanced early recovery within optimized ERAS protocols, though long-term superiority over high-quality navigation remains inconclusive. Conclusion: Amplivision offers a CT-free, radiation-sparing precision layer that enables standardized three-plane alignment and gap-guided balancing in both routine and complex arthroplasty. Its device-level control of rotational alignment complements coronal accuracy, with service-level benefits driven by outlier suppression rather than mean shifts alone. Robotic platforms provide incremental gains in dispersion control and early recovery when supported by mature ERAS pathways and institutional resources. Future multicentre trials should pre-register distributional radiographic endpoints, kinematic and gap metrics, cause-specific revision rates, and ≥5-year survivorship to rigorously quantify Amplivision’s comparative value against imageless and robotic technologies.