Trigger Point Injection for Myofascial Pain Syndrome in the Low Back: A Randomized Controlled Trial

Rationale: Low back pain (LBP), or myofascial pain syndrome (MPS) of the low back, accounts for approximately 2.63 million visits in the United States, or 2.3 percent of annual Emergency Department (ED) visits. An estimated 100 billion dollars per year is lost from LBP. Approximately one-third of this is direct costs. Previous studies have established the safety of trigger point injections (TPI). However, the results of these studies are highly heterogeneous regarding TPI's ability to treat pain or improve functional outcomes. The two most promising TPI studies conducted in the ED have been published in the last two years. They both suffered from a small sample size. Additionally, they suffered from a combination of limitations including: lack of randomization, inconsistent medical management, lack of a follow-up assessment, and lack of patient centered functional outcomes. These studies were both two armed and either compared standard medical management to TPI with local anesthetic or TPI with local anesthetic to TPI with Normal Saline (NS). One of these studies concluded that TPI is generally beneficial. The other concluded that TPI with NS is superior.

Research Hypothesis: The investigators hypothesize that standard therapy (ST) plus TPI with 8 mL of 0.5 percent Bupivacaine is superior to ST alone or ST plus TPI with 8 mL of NS for the treatment of the pain associated with MPS of the low back.

Significance: This will be the first TPI study to compare ST, to TPI with local anesthetic, and TPI with NS for LBP conducted in an ED. It will also be the first TPI study to incorporate a patient centered functional outcome and patient follow-up after discharge from an ED. TPI's are a popular treatment modality for LBP among many Emergency Medicine Providers. However, to date, there is limited evidence for or against it. The investigators are hopeful that this study will answer whether or not trigger point injections are benefiting patients and, if so, which type of TPI is most beneficial.