OR14: A SAFETY STUDY OF AUTOLOGOUS MESENCHYMAL PRECURSOR CELLS IN THE MANAGEMENT OF NON UNION OF TIBIAL AND FEMORAL FRACTURES

Abstract

Traditionally autologous bone graft is the standard treatment for non-union of fractures. More recently osteo-inductive agents with or without allograft have been utilised. A trial of Autologous Mesenchymal Precursor Cells has been completed at the Royal Melbourne Hospital to investigate their potential for the treatment of nonunion of long bone fractures.

With the approval of the ethics committee at the Royal Melbourne Hospital a human safety trial was commenced for the treatment of fracture non-union. Bone marrow cells were harvested from patients approximately six weeks before surgery and cultured in a laboratory. The cells were expanded in a culture medium. At the time of definitive surgery the stem cells were implanted on a hydroxy apatite/tricalcium phosphate matrix to the non-union site. Any further fixation that was required at the time of the union was performed by the treating surgeon. Investigations were performed at regular intervals to assess for union and for any reaction to the stem cells and growth medium.

The trial has been completed and eleven patients have been entered into the study. There were eight patients with non-union of femoral fractures and four patients with tibial non-unions (one patient with ipsilateral injuries to both bones). The average age was 41.9 years and the mean time to surgery from the initial injury was 15.2 months. Eight patients have united at a mean time of 24 weeks. One is well on the way to union and of the remaining two patients one is listed as uncertain and one a declared non union. The patient who has failed to unite is currently awaiting further surgery. One patient withdrew from the trial after ceasing smoking and finally uniting prior to stem cell implantation. There has been one adverse event with possible infection at a screw site though this was thought not to be related to stem cell therapy.

This is a phase one safety trial of a new development for the treatment of a nonunion of long bone fractures. The results are promising with the regards to achieving bone union without any significant complications. This paves the way for a trial involving allogeneic stem cells.