The potential of cells derived from human umbilical cord(UC) for orthopaedic cell engineering is evaluated by dissecting the UC into four distinct anatomical structures – cord lining (CL), Wharton's Jelly (WJ), umbilical cord artery (UCA) and umbilical cord vein (UCV). Cells from individual anatomical layers were grown by explant culture technique for 21 days. Tri-lineage differentiation and growth kinetics of cells from each layer were compared. Flowcytometry was done according to ISCT criteria to ascertain their surface antigen expressions. Cells from all four layers differentiated into bone, cartilage and fat. Osteogenic and chondrogenic differentiation was variable for each type of cells. All cells expressed surface antigens characteristic of mesenchymal stem cells (MSC). These cells can form a potential cell source in cell engineering to produce bone and cartilage although individual cell type needs to be characterised from each anatomical layer of UC and identify the best cell type for cell engineering.

Tissue engineering is an increasingly popular method of addressing pathological disorders of cartilage. Recent studies have demonstrated its clinical efficacy, but there is little information on the structural organisation and biochemical composition of the repair tissue and its relation to the adjacent normal tissue. We therefore analysed by polarised light microscopy and immunohistochemistry biopsies of repair tissue which had been taken 12 months after implantation of autologous chondrocytes in two patients with defects of articular cartilage.

Our findings showed zonal heterogeneity throughout the repair tissue. The deeper zone resembled hyaline-like articular cartilage whereas the upper zone was more fibrocartilaginous. The results indicate that within 12 months autologous chondrocyte implantation successfully produces replacement cartilage tissue, a major part of which resembles normal hyaline cartilage.

We describe a technique for measuring the Stiffness of regenerate bone after leg lengthening. This allows early identification of slow healing by reference to normal patterns. We determined the time of removal of the fixator from clinical and radiological information independent of the stiffness result.

In a series of 30 leg lengthenings there were no refractures when the tibial stiffness had reached 15 Nm/° or the femoral stiffness 20 Nm/°. Three refractures occurred at lower stiffness values. The technique is simple to perform, will allow a reduction in plain radiography and is recommended for routine postoperative management.