Long-term outcome for large meniscal defects treated with small intestinal submucosa in a dog model

Background: Large meniscal defects are a common problem for which current treatment options are limited. Hypothesis: Treatment of posterior medial meniscal defects in dogs with small intestinal submucosa is superior to partial meniscectomy in terms of clinical limb function, chondroprotection, and amount and type of new tissue in the defect. Study Design: Controlled laboratory study. Methods: A total of 51 mongrel dogs underwent medial arthrotomy with creation of standardized meniscal defects. The dogs were divided into groups based on defect treatment: small intestinal submucosa meniscal implant (n = 29) or meniscectomy (n = 22). The dogs were assessed for lameness by subjective scoring after surgery and sacrificed at 3, 6, or 12 months and assessed for articular cartilage damage, gross and histologic appearance of the operated meniscus, amount of new tissue in the defect, equilibrium compressive modulus of meniscal tissue, and relative compressive stiffness of articular cartilage. Results: Dogs in the meniscectomy groups were significantly (P < .001) more lame than dogs treated with small intestinal submucosa. Joints treated with small intestinal submucosa had significantly (P < .001) less articular cartilage damage, based on india ink staining, than did those treated with meniscectomy. Menisci receiving small intestinal submucosa had more tissue filling in the defects than did menisci receiving no implants, and this new tissue was more mature and meniscus-like and better integrated with remaining meniscus. Conclusion: Small intestinal submucosa scaffolds placed in large meniscal defects resulted in production of meniscus-like replacement tissue, which was consistently superior to meniscectomy in amount, type, and integration of new tissue; chondroprotection; and limb function in the long term. Clinical Relevance: Small intestinal submucosa implants might be useful for treatment of large posterior vascular meniscal defects in humans.