Direct Anterior Total Hip Arthroplasty Using the Muller Line-to-Line Cement Technique: A Propensity Score Matched Cohort Analysis.

Abstract

Background: Cemented fixation in primary total hip arthroplasty (THA) has seen renewed interest alongside the increasing adoption of the direct anterior (DA) approach. However, integrating cementation techniques with the DA approach poses challenges, particularly in patients who have morphologies complicating femoral exposure and access. The objective of our study was to assess the feasibility and radiographic outcomes of the Müller line-to-line ('French Paradox') cementation technique in primary cemented DA-THA, compared to a propensity-score-matched (PSM) cohort undergoing press-fit (cementless) DA-THA.

Methods: A retrospective analysis was conducted on patients undergoing primary cemented DA-THA using the Müller line-to-line ('French Paradox') cementation technique between 2016 and 2018. A PSM control cohort with comparable demographics undergoing press-fit DA-THA was generated. A total of 202 patients (101 per cohort) were included. Patients in the cemented group received a polished stainless-steel stem, while the press-fit group utilized a tapered-wedge titanium alloy stem. Radiographic outcomes, including stem malposition, radiolucency > two mm, cement mantle integrity, canal fit-and-fill, and implant stability, were assessed at a mean follow-up of 1.7 years using univariate and multivariate analyses.

Results: Symmetric bilateral femoral cortical thinning was observed in 10.8% of the cemented DA-THA cohort, attributed to physiological aging, with no instances of stem malposition, subsidence, or cement mantle compromise. In contrast, 5.9% of patients in the PSM press-fit DA-THA cohort experienced periprosthetic fractures or subsidence requiring revision surgery.

Conclusions: While numerous clinical registry studies have driven renewed interest in primary cemented THA, most have focused on conventional cementation techniques performed via posterior or antero-lateral approaches. This study demonstrates that primary DA-THA using the Müller line-to-line cementation technique delivers excellent radiographic outcomes while improving operative efficiency and adaptability in challenging morphologies. Long-term data collection is ongoing to validate these findings.