The Influence of Nonanatomical Insertion and Incongruence of Meniscal Transplants on the Articular Cartilage in an Ovine Model

Abstract

Background Adequate size matching and anatomically correct positioning must be recognized as essential factors influencing the outcome of meniscal transplantation. Hypothesis Nonanatomical insertion and incongruence of meniscal transplants has an influence on the development of degenerative changes. Study Design Controlled laboratory study. Methods Ten female sheep were used for this animal study. Both knees (N = 20) were divided into 3 groups, subjected to either meniscectomy (group I; n = 10), to a medial meniscal autograft transplantation with a nonanatomical insertion of the anterior and posterior horn (group II; n = 5), or a meniscal autograft transplantation from the opposite knee as an incongruent meniscal autograft (group III; n = 5). After 6 months, radiographic (Fairbank's criteria), macroscopic (Jackson score), and histological evaluation by light microscopy (Mankin score) and scanning electron microscopy of the articular cartilage was performed. Results All applied evaluation methods demonstrated that nonanatomical insertion of meniscal transplants resulted in the highest amount of degenerative cartilage changes. The histological assessment even revealed a significantly enlarged cartilage damage for the non-anatomic-positioned meniscal transplants in relation to the meniscectomized knees. Furthermore, the incongruent meniscal transplants demonstrated a significantly better cartilage situation than nonanatomically inserted meniscal transplants. Conclusion The histological evaluation demonstrated clearly that a nonanatomically inserted meniscal transplant leads to degenerative cartilage changes that are worse than that after meniscectomy. Clinical Relevance Precise anatomic positioning is mandatory for the potential chondroprotective effect of meniscal transplants.