Chronic post-surgical pain is a significant problem because it results in decreased activities of daily living, reduced quality of life, and overutilization of medication and healthcare resources, so it’s very costly. The main cause is peripheral stimulation, because of course once a surgeon breaks the skin he’s cutting sensory nerves and you have the neuron developing a neuroma which has ectopic or spontaneous conduction. You have dorsal root ganglion and dorsal horn of the spinal cord changes which because of constant peripheral input can induce central sensitization. You then have the pain go up through the brainstem into the limbic system including the hypothalamus, then to the cortex and then it goes back down. So this is all neurologically-based but it’s also significantly psychologically-based. Pre-emptive analgesia may be helpful if engaged correctly. What you want to do, I believe is use the antihyperalgesic drugs such as a combination of gabapentin and Celebrex (or celecoxib) for two to three weeks so that you develop a new homeostasis and the patient goes into surgery with significant changes in how the synapses work and how certain drugs are functioning.