Autologous perichondral tissue for meniscal replacement

Our aim was to examine the potential of autologous perichondral tissue to f orm a meniscal replacement. In 18 mature sheep we performed a complete medi al meniscectomy. The animals were then divided into two groups: 12 had a me niscal replacement using strips of autologous perichondral tissue explanted from the lower rib (group G) and six (group C) served as a control group w ithout a meniscal replacement. In all animals restriction from weight-beari ng was achieved by means of transection and partial resection of tendo Achi llis. Six animals (four from group G and two from group C) were each killed at 3, 6 and 12 months. The grafts and the underlying articular cartilage w ere removed and studied by gross macroscopic examination, light microscopy, SEM, polarised light examination, and by biomechanical tests. In all the transplanted animals a new perichondral meniscus developed. Afte r three months the transplants resembled normal menisci in size and thickne ss, while in the control animals only small rims of spontaneously grown tis sue were seen. Microscopically, the perichondral menisci showed a normal or ientation of collagen fibres and normal cellular characteristics, but in th e central region, areas of calcification disturbed the regular tissue diffe rentiation. Healing tissue in control animals lacked the normal fibre orien tation and cellularity, SEM of perichondral menisci showed surface characte ristics similar to those of normal sheep menisci without fissures and lacer ations; the control specimens had these defects. The femoral and tibial car tilage in contact with the new menisci had normal surface characteristics a part from one animal with slight surface irregularities. Control animals sh owed superficial lesions after three months which increased at six to 12 mo nths postoperatively. Microangiography of the newly grown tissue demonstrat ed a less intense vascularisation after three months when compared with nor mal menisci. The failure stress and tensile modulus of perichondral menisci were signifi cantly lower than those of normal contralateral menisci, and spontaneously regenerated tissue in meniscectomised animals had even lower values. There were no significant differences in values between newly grown perichondral menisci and spontaneously grown tissue.