Evaluation of a porous polyurethane scaffold in a partial meniscal defect ovine model

Purpose: The objective of this study was to assess the performance of a degradable porous polyurethane scaffold in a partial meniscectomy ovine model. Methods: We subjected 42 skeletally mature ewes to unilateral partial excision of the lateral meniscus. In 19 animals the defect was left unfilled; in 23 animals a scaffold was inserted. Knees were examined by magnetic resonance imaging, gross inspection, and histologic inspection of the cartilage of the tibial plateau. Results: In contrast to what has been previously reported in a complete meniscal replacement model, cartilage damage did not occur under the site of scaffold implantation; this was likely influenced by the rapid infiltration of cells and the dense tissue that formed within the scaffold. Cartilage damage in both groups was located close to the midline of the joint. No significant difference in the condition of the articular cartilage of the tibial plateau was seen between groups up to 12 months postoperatively. This result was influenced by the fact that the partly meniscectomized knees also showed unexpected tissue regeneration within the defect site, which raises concern about the suitability of using a partial meniscectomy as a control in the ovine model. Conclusions: Our study has shown that implantation of a polyurethane scaffold in a partial meniscectomy ovine model promotes tissue ingrowth without damaging the cartilage with which it articulates. Clinical Relevance: Meniscal deficiency is a common occurrence, the effective clinical management of which is limited by the absence of an off-the-shelf implantable construct.