MRI and histology of collagen template implantation and regeneration in rabbit knee meniscus

Purpose: To evaluate, using magnetic resonance (MR) imaging and histology, the regeneration of injured knee menisci following reconstituted collagen template implantation in rabbits. Materials and methods: Twenty adult rabbits were divided into five groups: (A) partial meniscectomy of the medial meniscus (1/3 of the anterior horn) with collagen template implantation in the left knee (n = 4); (B) partial meniscectomy of the medial meniscus (1/3 of the anterior horn) with collagen template implantation in the right knee (n = 4); (C) partial meniscectomy (1/3 of the anterior horn) of the medial meniscus of the left knee (n = 4); (D) sham operation (n = 4); (E) no operation (n = 4). All rabbits were killed after follow-up MR imaging at 8 weeks for histologic analysis. Results: In groups A and B, the signal intensity decreased, and the last MR imaging showed homogeneous low signal intensity in 6 of 7 injured menisci, suggestive of regeneration. One rabbit in group B died. The seventh rabbit showed higher signal intensity in the injured meniscus than in the control meniscus, indicating failure of regeneration. Group C animals showed irregular margins and high signal intensity in the injured meniscus without regeneration. Conclusion: Implantation of reconstituted collagen template can facilitate the regeneration of injured knee menisci in rabbits. The gradually decreased MR signal of the meniscus indicates the maturation of regeneration.