Line-to-line cementation in hip arthroplasty : what is the current role of the 'French Paradox'?

Abstract

The 'French Paradox' cementing technique challenges conventional principles of femoral component fixation by advocating line-to-line femoral component insertion and a thin cement mantle of variable thickness. This contradicts the widely accepted recommendation of a 2 mm to 4 mm cement mantle thickness. However, this approach has shown good clinical results. This review aims to summarize the current evidence regarding the clinical outcomes, biomechanical analysis, and ongoing controversies surrounding the French Paradox cementing technique in total hip arthroplasty (THA). A systematic literature search was conducted to identify studies investigating the concept of line-to-line cementing, or the French Paradox, in the context of primary THA. Studies were identified through database searches (PubMed/MEDLINE, Embase, Web of Science, and Cochrane Library) up to March 2025 and selected based on predefined criteria. Data extraction and quality assessment were performed independently. Due to methodological heterogeneity, findings were synthesized narratively, following PRISMA guidelines. Biomechanical data support the effectiveness of the line-to-line cementing technique, showing superior rotational stability and adequate fixation even in osteoporotic bone. Clinical studies report excellent survivorship rates, with ten- and 17-year implant survival exceeding 90% in multiple cohorts. Subsidence and migration patterns are comparable with, or better than, those observed with standard undersized cementing techniques. No increased risk of aseptic loosening or other specific failure mechanisms was identified. However, studies focusing on patient-reported outcome measures remain limited. The French Paradox cementing technique represents a reliable alternative for femoral component fixation, particularly with taper-slip designs, despite deviating from conventional cementing strategies. Further high-quality prospective studies are needed to clarify its optimal indications and to standardize its definition in the literature.