The variance of nerve axon to muscle fibre ratio and its effect on outcome in functional muscle transfer

The results of functional muscle transfer for the treatment of facial palsy are varied. Surgical technique in such cases remains constant with only the selected ramus of the buccal branch of the facial nerve changing. Differing sized branches of the facial nerve in the rabbit were used to reinnervate a constant sized muscle transfer to see if this might explain the spectrum of clinical results seen and additionally provide some insight into the phenomenon of "late onset tightening" seen in some cases. Peripheral limb reconstruction using functional muscle transfer following injury or tumour resection has been widely reported in the literature. The results of such procedures often fail to deliver the physiological strength that might be hoped for in relation to the size of the transferred muscle. Differing sized pure motor nerves were used to reinnervate a constant sized muscle transfer to see if functional results could be improved in an experimental model analogous to peripheral limb reconstruction. The rectus femoris muscle in the New Zealand White rabbit was used as a standardised muscle transfer for investigation into how the reinnervating axonal load affects outcome, defined in terms of physiological force developed by the muscle post-operatively, looking at both the central and peripheral nervous systems. Corroboratory investigations were also undertaken to determine the reinnervating characteristics of the nerves studied and those of reinnervated muscle