Postoperative methocarbamol, opioid requirements, and pain after extensive spine fusion surgery: a retrospective cohort study
In a retrospective cohort study of 1,467 adults undergoing extensive spine fusion, postoperative methocarbamol was associated with increased opioid consumption and pain scores but also correlated with a shorter hospital stay, reduced delirium, and improved oxygenation.
Original paper licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
After a major surgery, the body often reacts with a deep, aching stiffness. In the days following an operation, muscles can spasm, tightening up in a way that makes movement painful and difficult. For decades, doctors have relied on a class of medicines called muscle relaxants to ease this tension, hoping that by loosening the muscles, they would also lower the need for powerful painkillers known as opioids. These drugs are effective at stopping pain, but they carry significant risks, including the potential for long-term dependence and dangerous side effects. Because of this, the medical community has been eager to find ways to manage pain without leaning so heavily on opioids, leading many surgeons to routinely prescribe muscle relaxants alongside their standard pain management plans.
However, the assumption that these relaxants actually reduce pain or opioid use has never been fully proven, especially for patients undergoing the most extensive and invasive procedures. To test whether this common practice truly helps, researchers at the Cleveland Clinic looked back at the records of nearly 1,500 adults who had undergone major spine fusion surgery between 2018 and 2024. This type of surgery involves joining together at least three vertebrae, a procedure that requires significant manipulation of the back muscles and typically results in a challenging recovery. The team wanted to see if patients who received a specific muscle relaxant called methocarbamol within the first 12 hours after surgery fared better than those who did not receive it at all during the first two days.
The researchers compared two groups of patients: those who started taking methocarbamol early in their recovery and those who did not receive the drug for at least the first 48 hours. They carefully adjusted for differences between the groups, such as age and other health conditions, to ensure a fair comparison. What they found challenged the common belief that the drug would help. Patients who took methocarbamol actually required more opioid pain medication over the first 48 hours than those who did not take it. On average, the group using the muscle relaxant consumed 147 milligrams of morphine equivalents, compared to 98 milligrams for the group that did not use it. Furthermore, these patients reported higher pain scores, averaging 5.1 on a scale of zero to ten, while the non-users averaged a score of 4.0. Crucially, the study was designed to prove that the drug was at least "non-inferior"—meaning it did not make pain or opioid needs significantly worse. The data showed that methocarbamol failed to meet these non-inferiority margins for both pain and opioids, confirming that the drug did not spare patients from needing opioids, nor did it make their pain more manageable.
Despite these disappointing results regarding pain and medication use, the study uncovered some surprising benefits in other areas of recovery. Patients who received methocarbamol spent less time in the hospital, with a median stay of six days compared to seven days for those who did not take the drug. More importantly, the group using the muscle relaxant experienced significantly fewer cases of delirium, a state of confusion and disorientation that can occur after surgery. Only 12 percent of the methocarbamol group developed delirium, whereas 34 percent of the patients who did not take the drug experienced it. Additionally, the patients on the muscle relaxant maintained slightly better oxygen levels in their blood during the first two days after surgery.
The authors suggest that while methocarbamol did not achieve its primary goal of reducing pain or opioid consumption, its ability to reduce delirium and shorten hospital stays might be linked to how it affects the body's overall recovery process. It is possible that by easing muscle tension, the drug allowed patients to move around and participate in physical therapy sooner, which is known to help prevent confusion and respiratory issues. The study does not prove that the drug causes these positive outcomes, but the association is strong enough to suggest that the drug's value may lie in these secondary benefits rather than in pain relief. The findings indicate that for patients undergoing extensive spine fusion, adding methocarbamol to a pain management plan does not reduce the need for opioids or lower pain scores, and it may even be associated with higher pain levels. This suggests that the routine use of this muscle relaxant for the purpose of opioid sparing may not be supported by the evidence, even if it offers other advantages for patient recovery.
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