Epiphyseal replacement using developing tissue donors in a murine model: a combined histologic and radiographic study

Vascularized Fibular Epiphyseal Transplantation for Limb Salvage Following Bone Tumour Excision

Vascularized fibular transplantation has found wide application for long bone reconstruction in both congenital and acquired defects. However, in children the growth of these transplants is limited and requires the epiphysis if it is to be substantial. Also, the reconstruction of a joint is best achieved with autologus hyaline cartilage. Vascularized fibular epiphyseal transplantation, thus, may play a role in limb salvage procedures in children to both preserve joint function and facilitate long bone growth. The present paper discusses the history of vascularized epiphyseal transplantation both in the laboratory and clinical realm. In discussing its advantages and associated problems, special emphasis is directed at the vascular factors, the endocrine environment, the innervation, mechanical stressors, the recipient site and the donor site. Two case examples are presented to demonstrate the technique, the results and the long term outcome.

Repopulation of laser-perforated chondroepiphyseal matrix with xenogeneic chondrocytes. An experimental model

Growth of chondrocytes into a xenogeneic chondroepiphyseal matrix was investigated in an in vitro experimental model by combining viable calf chondrocytes with chick epiphyseal matrix devoid of viable chondrocytes. The chondrocytes were harvested from the wrist joints of newborn calves and cultured for 2 days. The epiphyses were harvested from the distal femurs and the proximal tibias of fetal chicks after development was arrested at 17 days by freezing. The epiphyseal specimens were prepared in four ways. These included femoral and tibial epiphyses without holes and femoral and tibial epiphyses with holes made by a laser. These epiphyseal specimens were co-cultured with calf chondrocytes for various periods. After digestion of the epiphyseal matrix, viable chondrocytes were counted in suspension. Chondrocyte division in the matrix was assessed by [3H]thymidine incorporation. The growth of calf chondrocytes into the xenogeneic chick matrix was evaluated by fluorescence microscopy on fresh thick epiphyseal sections. The percentage of viable chondrocytes in the xenogeneic epiphyseal matrix increased with culture time to a maximum at day 21. The addition of laser-drilled holes was found to extend a plateau of chondrocyte viability until day 29. A decrease in cell viability was detected at later observation points. This study demonstrates that xenogeneic matrix may serve as a morphogenetic scaffold for chondrocytic growth.

Physeal replacement with cultured chondrocytes of varying developmental time: failure to reconstruct a functional or structural physis

Reconstruction of physeal regions excised from the distal femoral chondroepiphysis was attempted in a murine model. Cultured chondrocytes of varying developmental time from the same inbred strain of mice were used for replacement. Vascularity, matrix formation, and cell division, as well as growth, were assessed. The cultured chondrocytes did not produce growth. Consistent with this, cell division, as assessed with incorporation of tritiated thymidine, was not normal. However, the cultured chondrocytes did receive a nutritional supply from the host and did continue matrix formation after transplantation.

Physeal reconstruction using tissue donated from early postnatal limbs in a murine model

Physeal reconstruction was performed in a murine model by transplanting corresponding postnatal tissue from 4-day-old C57B mice to resection defects. The site of the reconstruction, the murine distal femoral epiphysis, is completely cartilaginous and avascular at this stage of development. The tissue transplanted into the defect was demonstrated to have high kinetic activity by its incorporation of tritiated thymidine. The physeal reconstruction as performed restored only 25% of normal growth. While transplanting cell populations is feasible, the method will require a great deal of work before clinical application.

Hemiepiphyseal reconstruction using tissue donated from fetal limbs in a murine model

Epiphyseal reconstruction in the immature skeleton could have great clinical significance. Hemiepiphyseal reconstruction was performed in a murine model by transplanting fetal tissue to surgically created defects in postnatal mice. Reconstruction is facilitated by the existence of inbred strains. While the reconstruction as performed here did not completely restore the growth characteristics of the epiphysis, the model represents a potentially fruitful interface between basic and clinical biology.