Introduction to Multimodal Analgesia in Spine Surgery

Spinal fusion surgery is widely recognized as one of the most painful surgical procedures, often requiring intensive early post-surgical pain management. Historically, clinicians relied heavily on high-dose opioid therapy to manage acute postoperative distress. However, excessive opioid reliance brings substantial risks, including respiratory depression, postoperative nausea and vomiting, bowel dysfunction, prolonged hospital length of stay, and long-term opioid dependence. To mitigate these risks, Enhanced Recovery After Surgery (ERAS) protocols advocate for multimodal analgesia regimens. These protocols incorporate non-opioid adjuncts designed to target different pain pathways synergistically, thereby optimizing pain control while decreasing total narcotic exposure. Among the non-opioid medications frequently integrated into spinal surgery ERAS pathways, ketamine and pregabalin have gained widespread clinical traction. Although both agents are routinely prescribed, clinical uncertainty persists regarding their comparative efficacy, dosage safety, and overall impact on postoperative opioid usage in adults undergoing complex instrumented spinal fusion procedures.

Opioid Management in Spinal Fusion Protocols

Managing severe incisional and deep tissue pain following instrumented spinal fusion presents unique clinical challenges. Surgical trauma affecting bone, muscle, and surrounding neural structures triggers intense inflammatory and neuropathic pain responses. Patients entering spine surgery frequently present with baseline chronic pain and pre-existing opioid tolerance due to conservative pre-surgical management. Consequently, standard postoperative opioid regimens often fail to deliver adequate analgesia or lead to escalating dose requirements that trigger adverse drug events. Multimodal pain management strategies aim to interrupt pain signaling across peripheral and central sensory pathways simultaneously. By combining agents with distinct mechanisms of action, clinicians can achieve additive or synergistic pain relief. Within ERAS protocols, adjunctive non-opioid medications serve as vital components in decreasing reliance on rescue opioids. Recent clinical investigations have focused on evaluating how targeted perioperative interventions can significantly curb postoperative opioid usage while facilitating earlier patient mobilization, reducing perioperative complications, and shortening hospital stays following major spinal reconstruction.

Evaluating Ketamine and Pregabalin Efficacy

Ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, inhibits central sensitization and hyperalgesia triggered by severe surgical nociception. By preventing NMDA receptor activation in the spinal cord, low-dose perioperative ketamine attenuates acute pain perception and blunts the development of acute opioid tolerance. On the other hand, pregabalin is a gabapentinoid that binds to the alpha-2-delta subunit of voltage-gated calcium channels in central nervous system tissue. This binding reduces the presynaptic release of excitatory neurotransmitters, effectively dampening neuropathic pain signals arising from surgical nerve root manipulation. Both medications offer plausible physiological pathways to reduce postoperative opioid usage, yet direct head-to-head clinical trials comparing their efficacy remain limited. Consequently, systematic reviews and network meta-analyses offer essential indirect comparisons, allowing surgical teams and anesthesiologists to evaluate the comparative clinical utility and safety profiles of perioperative ketamine versus varying doses of pregabalin in major spinal procedures.

Comparative Analysis of Postoperative Opioid Usage

A comprehensive network meta-analysis evaluated thirteen randomized controlled trials comprising 879 adult patients undergoing instrumented spinal fusion. The study systematically analyzed outcomes across groups receiving perioperative ketamine, pregabalin, or control interventions. Six trials provided extractable data on cumulative 24-hour opioid consumption measured in oral morphine milligram equivalents (MME). Using pregabalin 150 mg as a baseline reference, perioperative ketamine administration demonstrated a significant reduction in 0-24-hour postoperative opioid usage, with a mean difference of -56.99 mg MME (95% confidence interval: -99.56 to -14.43). In contrast, control regimens resulted in higher opioid consumption (mean difference +21.31 mg MME), whereas pregabalin 300 mg yielded a modest, non-significant reduction (mean difference -13.22 mg MME) compared to pregabalin 150 mg. These findings highlight that while both non-opioid adjuncts contribute to opioid-sparing protocols, ketamine exhibits a particularly pronounced point estimate for early narcotic reduction following complex spinal fusion procedures.

Pain Scores and Adverse Event Profiles

Analgesic efficacy was further evaluated across seven randomized trials reporting 24-hour Visual Analog Scale (VAS) pain scores. Control groups experienced significantly higher pain intensity compared to patients receiving pregabalin 150 mg, showing a mean difference of +0.84 VAS units (95% confidence interval: +0.01 to +1.66). Conversely, 24-hour VAS pain scores were statistically comparable between ketamine, pregabalin 300 mg, and pregabalin 150 mg, demonstrating that both non-opioid agents provide effective, equivalent early post-surgical analgesia. Safety evaluations across the included trials indicated that adverse events, including sedation, dizziness, nausea, and psychotomimetic effects, were generally infrequent and comparable to control groups. While ketamine demonstrated a larger point estimate in curbing postoperative opioid usage, the broad confidence intervals inherent to indirect network comparisons highlight the need for cautious interpretation. Current evidence confirms that both agents offer robust, safe opioid-sparing benefits within ERAS spinal surgery protocols.

Clinical Implications for Surgical Protocols

The clinical evidence confirms that incorporating either ketamine or pregabalin into perioperative multimodal analgesia protocols yields clinically meaningful reductions in early narcotic requirements without compromising pain control. Surgeons and anesthesiologists can confidently utilize either agent to optimize post-surgical ERAS pathways. However, given the indirect nature of current meta-analytic comparisons and variations in institutional dosing practices, definitive superiority between ketamine and pregabalin cannot be established without robust direct comparisons. Future research must prioritize adequately powered, head-to-head randomized controlled trials using standardized dosing protocols, long-term functional recovery metrics, and precise adverse event tracking. In daily clinical practice, selecting between ketamine and pregabalin should consider individual patient risk factors, baseline opioid tolerance, renal function, and institutional familiarity to achieve safe, effective reduction in postoperative opioid usage after spinal fusion.

Frequently Asked Questions

What is the main benefit of adding ketamine or pregabalin to spinal fusion pain management?

Both ketamine and pregabalin serve as non-opioid adjuncts that significantly reduce overall postoperative opioid usage during the first 24 hours after spinal fusion surgery. By targeting distinct central nervous system pain pathways, these medications enhance pain relief while minimizing standard opioid-related side effects such as respiratory depression, sedation, urinary retention, and postoperative nausea.

How does ketamine compare directly to pregabalin in reducing opioid consumption?

In network meta-analysis, perioperative ketamine demonstrated a larger point estimate for reducing 24-hour postoperative opioid usage compared to pregabalin 150 mg. However, because these findings rely on indirect study comparisons with wide confidence intervals, both agents are currently considered comparable options for early post-surgical opioid sparing within multimodal ERAS pathways.

Are there significant safety concerns when using these medications for spinal fusion patients?

Across analyzed clinical trials, adverse events associated with low-dose perioperative ketamine or pregabalin were generally infrequent and comparable to control groups. When administered under standardized clinical protocols, both agents offer safe analgesic profiles without significantly increasing the incidence of adverse drug events or complications following instrumented spinal fusion.

Disclaimer: This content is for informational and educational purposes only. It is not intended to provide medical advice or to replace clinical judgment. Healthcare professionals should consult primary literature and follow relevant local and national guidelines for patient management.

References

Coffin M et al. Comparison of Ketamine and Pregabalin on Postoperative Opioid Usage and Pain Management in Spinal Fusion: Systematic Review and Network Meta-analysis. J Clin Neurosci. 2026 Aug 07. doi: undefined. PMID: 42566840.