Predictors of failure and clinical outcomes in patients undergoing meniscal substitution with meniscus scaffold or meniscus allograft transplantation

Meniscal deficiency is a major cause of knee pain and functional impairment and represents a well-recognized risk factor for early osteoarthritis following meniscectomy. Biological meniscal substitution aims to restore joint biomechanics, reduce contact pressures, and delay degenerative progression. Currently, two main strategies are available: meniscal scaffolds for partial defects and meniscal allograft transplantation (MAT) for subtotal or total meniscal loss. However, predictors of failure and long-term determinants of success remain incompletely defined. This thesis investigated clinical outcomes and risk factors in patients undergoing meniscal substitution through two complementary studies. The first study evaluated long-term results after collagen meniscus scaffold implantation in 92 patients at a mean follow-up of 11.8 years. Significant improvements in patient-reported outcomes were observed, with 75% of patients achieving acceptable symptom states. Surgical failure occurred in 13% of cases. Advanced cartilage damage (Outerbridge III–IV) and a delay of ≥5 years from meniscectomy to scaffold implantation were independent predictors of inferior outcomes, emphasizing the importance of early intervention and careful cartilage assessment. The second study analyzed 360 consecutive MAT procedures with a mean follow-up of 8.8 years. Overall survival was favorable; however, donor–recipient sex mismatch emerged as a strong independent predictor of surgical failure. Non-concordant transplants demonstrated significantly reduced survivorship, particularly when a male graft was implanted in a female recipient. In contrast, age, body mass index, and blood group mismatch were not associated with failure. Collectively, these findings highlight that meniscal substitution can provide durable clinical benefit, but outcomes are strongly influenced by biological and patient-specific factors. Beyond traditional criteria such as alignment and cartilage status, donor–recipient sex matching may represent a novel determinant of MAT survival. These results support a more personalized approach to meniscal restoration, refining patient selection and tissue allocation strategies.