Surface engineering strategies for PET-Based ligament scaffolds in anterior cruciate ligament reconstruction: a systematic review of mechanical and biological performances

Abstract

ACL reconstruction is among the most common orthopedic procedures, yet autografts and allografts carry significant limitations including donor site morbidity and immunological risk. PET-based synthetic grafts such as LARS were introduced to address these shortcomings, but their biologically inert surface raises concerns regarding cellular adhesion and host tissue integration. A new generation of functionalized PET scaffolds has emerged over the past decade, yet no systematic review has summarized this evidence since 2011. The present review aims to evaluate the biological and mechanical effects of novel functionalized PET scaffolds for ACL reconstruction. A systematic review was conducted in accordance with the PRISMA 2020 statement. PubMed, Embase, and Web of Science were searched up to 20 August 2026 for original studies investigating chemically or biologically modified polyethylene terephthalate grafts for Anterior cruciate ligament reconstruction and reporting in vitro outcomes, in vivo animal model data, and mechanical properties. Two independent reviewers performed screening, full-text assessment, and data extraction. Seventeen studies met the inclusion criteria. Functionalization strategies included physical deposition, chemical surface modification, biomimetic mineral coatings, and hybrid composite fabrication. Across all studies, functionalized PET scaffolds generally demonstrated improved performance compared with unmodified PET controls. In vitro , enhanced cellular proliferation, upregulation of osteogenic markers, and increased angiogenic activity were observed. In vivo , improved graft–bone integration was demonstrated by higher bone volume fraction, reduced tunnel area, and decreased interface width. Post-implantation ultimate load to failure and stiffness generally favored functionalized PET scaffolds, though both parameters remained inferior to the native ACL in direct comparisons. Surface biofunctionalization appears to enhance the biological and mechanical performance of PET-based scaffolds for ACL reconstruction, suggesting that surface bioengineering may play an important role in promoting biological integration and functional performance. These findings indicate that functionalized PET scaffolds could represent potential donor-independent alternatives for ACL reconstruction and may warrant further investigation as synthetic ligament substitutes. However, a persistent mechanical gap versus native ligament tissue remains. These findings should be interpreted with caution due to methodological heterogeneity, predominant use of small animal models, and inconsistent outcome reporting across the included studies.