What Are the Optimal Sagittal Alignments in Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Abstract

Total knee arthroplasty (TKA) is a well-established intervention for end-stage osteoarthritis (OA), offering substantial pain relief and functional improvement. However, a considerable proportion of patients remain dissatisfied postoperatively due to multifactorial causes. While numerous studies have investigated implant alignment, the sagittal plane alignment has received comparatively less attention, and its clinical relevance remains controversial. This systematic review aims to identify the optimal sagittal alignment (SA) parameters in TKA and to evaluate their impact on clinical outcomes. A comprehensive literature search was conducted across four databases (PubMed, the Cochrane Library, Embase, and Web of Science) from their inception to April 1, 2025. Studies focusing on SA after primary TKA were considered. Articles meeting the inclusion and exclusion criteria were subjected to meta-analysis. The SA parameters assessed included tibial slope, posterior condylar offset, tibial and femoral component angles, femoral bowing angle, and tibiofemoral alignment. The search yielded 1414 articles, after removing duplicates, of which 30 studies met the final inclusion criteria. The review confirmed that SA plays a critical role in postoperative outcomes. Malalignment in the sagittal plane was associated with complications such as instability, hyperextension, and impaired functional recovery. In particular, deviations in tibial slope and femoral bowing angle significantly influenced overall limb alignment and joint mechanics. Although achieving proper SA appears to reduce complications and improve functional outcomes, no universally accepted target values have yet been established. Based on current evidence, achieving optimal SA during the perioperative period is essential for improving prosthesis longevity and patient satisfaction following primary TKA. Surgeons should pay close attention to SA parameters, and the use of emerging technologies is encouraged to enhance precision in component positioning. PROSPERO Registration: CRD42023471336.