Clinical Effectiveness of Pre-operative Methadone in Single Level Lateral Transpsoas Interbody Fusions

Lumbar spinal fusions are becoming increasingly popular and prevalent in the treatment of a variety of spinal pathologies, but predominantly for degenerative disease which is most prevalent in the obese and or older population. These operations can result in relatively high post operative surgical pain and necessitate significant post operative opioid consumption which can precipitate co-morbid medical conditions such as respiratory depression and failure, pneumonia, gastrointestinal ileus, deep venous thrombosis, and pulmonary embolism. Additionally, these medical comorbidities also represent an increased burden on healthcare expenditure with increased length of hospital stay, inpatient testing and treatment, and need for additional follow up. The investigators objective is to study the effect of a long term opioid analgesic, methadone, in a uniform population undergoing a single level minimally invasive lumbar fusion. The preoperative single dose administration of methadone has already been shown to be effective in improving post operative pain control in open multi-level spinal fusion patient populations and has become the standard of care in most surgical centers across the country. The long half-life of methadone results in improved steady state pharmacokinetics relative to other traditional opioids and is thought to improve pain control while decreasing consumption. In addition to Mu opioid receptor agonism, Methadone is thought to also have adjunctive analgesic and anti-tolerance effects due to CNS excitatory glutamatergic NMDA receptor antagonism. There are also reports of synergistic effects from serotonin and norepinephrine reuptake inhibition. The investigators predict that a single preoperative oral methadone administration can result in improved postoperative analgesia with requirement of less IV and PO traditional narcotics within the first 2 weeks post operatively and also will not increase co-morbid risks relative to traditional shorter acting opioid analgesics that are presently given preoperatively.