Objective: Meniscus regeneration is limited, moreover, loss of meniscal tissue leads to osteoarthritis. A new biomaterial, consisting of hyaluronic acid and polycaprolactone was applied as a meniscus substitute device in a study in sheep.

Methods: 24 sheep received a total medial meniscal replacement. Group SCF (n=12) was treated with a cell free scaffold, Group SCS (n=12) with a scaffold seeded with autologous chondrocytes harvested from the contralateral joints, which served as sham controls (n=12). Further 12 non-operated and 2 menisectomy controls were included in the study.

The animals were sacrificed after 4 months. The implants and joint surfaces were evaluated on a macroscopic (Implant Gross Assessment Score; Gross Assessment of Joints Score) and histological level.

Results: There was no significant difference of the Implant Gross Assessment score between the SCF and SCS groups. All implants showed excellent capsular ingrowth at the periphery. Dislocation, extrusion and tears occurred in part of the specimen due to biomechanical problems caused by soft tissue quality. The mean Gross Assessment of Joint Changes Score of the groups SCF and SCS was not statistically different. Cartilage damage was significantly more severe in joints with implants than in non-operated joints and sham controls, but less pronounced than in menisectomy controls. Histological evaluation showed residual scaffold with an associated foreign body response in all implants. Fibrous tissue was present in all implants, in contrast small foci of cartilaginous differentiation were more common in the cell-seeded constructs.

Discussion: At 4 months regenerative meniscal tissue was present but immature. The present study showed that strong biomechanical scaffold properties are a required to allow guided tissue regeneration and maturation under loading conditions. Cell seeding of the scaffold encourages cartilaginous differentiation. Modification of the scaffold and the cell-seeding technique will be investigated in further studies.

Meniscus has many important functions in the knee joint such as load bearing, shock absorption, joint stability, joint lubrication and proprioception. In the recent years, meniscus injuries have been the focus of orthopaedic surgeons and musculoskeletal tissue engineering applications because of its avascular nature.

In this study, we aimed to compare the regeneration capacities of two composite scaffolds in a New Zealand Rabbit meniscal defect model. The first scaffold consists Poly-Lactic Acid (PLA) + chitosan + loofah and the second PLA + Hydroxyapatite (HAp) + loofah. In order to produce these scaffolds; 4% chitosan, 4% PLA and 4% HAp solutions were seperately prepared. The loofah pieces were saturated with these solutions and vacuum-dried for 14 days and sterilized with ethylene oxide.

There were several characterizations performed such as Fourier Transform Infrared Spectroscopy (FTIR) for the investigation of chemical structure, Scanning Electron Microscopy (SEM) for morphological analysis, thermogravimetric differential thermal analysis (TGA/DTA) for thermal properties, mechanical compression and swelling ratio analysis. Moreover, in order to investigate biocompatibility of the scaffolds, WST-1 colorimetric assay at days 3, 7, 10, 14 and 21 was conducted.

After these biocompatibility analysis, a 1.5-mm cylindrical defect was created in the avascular portion of the anterior horn of the medial meniscus in 14 New Zealand rabbits (2.5–3 kg weight) which were randomly grouped in two. The scaffolds were implanted at the defect site with the help of a freshly prepared fibrin glue. 8 weeks after the operation, the rabbits were sacrificed and their tissues were kept for further mechanical, radiological and histological analysis.

In conclusion, we succeeded to produce a new meniscus scaffold. The proliferation ability of PLA + chitosan + loofah scaffold is higher than PLA + HAp + loofah scaffold. However, there was no statistically significant difference among them.

Purpose

To assess performance of a polyurethane scaffold designed to facilitate regrowth of tissue after irreparable partial meniscus tissue loss.