by Gary Zartman, M.D.
Since the Commonwealth of Pennsylvania legalized marijuana for medical usage in 2019 many patients have been using cannabis substances, such as CBD oils, for a variety of medical problems including chronic pain, seizure disorders, Glaucoma, sleep disorders, and nausea and vomiting. In the last few years cannabis has been promoted as an adjunct to opioid therapy for the management of pain related to musculoskeletal conditions. Very little is known about the actual effectiveness of these drugs, especially for the alleviation of symptoms of osteoarthritis or for the treatment of pain after hip or knee replacement. Many of my patients have asked me about their use and therefore I’ve done some research to give you the best information that we have currently. I will review for you findings published in the Journal of Arthroplasty as well as the Journal of the American Academy of Orthopedic Surgeons regarding the use of cannabis substances in orthopedic practice.
History of Marijuana
Cannabis sativa, or marijuana, has been used for several millennia for medical, recreational, and spiritual purposes. The Chinese reported the use of marijuana for peri-operative pain control in the 2nd century AD. Later, these drugs became popular in Europe for controlling pain, spasticity, and nausea. In 1854, cannabis was added to the US Pharmacopoeia for uses such as appetite stimulation, headache relief, sleep disorders, and sexual dysfunction. Medical cannabis fell out of favor in the early 1900s as its use became associated with crime and violence. The US Marijuana Tax Act was passed in 1937 and strictly outlawed marijuana for recreational use. In 1970, the FDA passed the Controlled Substances Act, which classified cannabis as a Schedule One substance, in effect outlawing its use and sale. Since that time research on the medical applications of cannabis has been limited to chronic pain and nausea management in patients with cancer, appetite stimulation in patients with AIDS, and some forms of spasticity. Cannabis has been recently legalized for medical use in 29 States and the District of Columbia, encompassing 63% of the United States population. Most of this legalization has been driven by public support but a lack of definite scientific evidence to support the efficacy of cannabis. Many states have also legalized cannabis for recreational use as well. The federal government, however, continues to maintain the classification of marijuana as a Schedule One substance, deeming it illegal for any use. This has limited any organized research efforts to determine the true efficacy of these drugs.
Marijuana and It’s Components
The cannabis plant contains over 60 active substances, two of the most widely known are THC, marijuana’s major psychoactive component, and cannabidiol (CBD). These substances react with the nervous and other systems throughout the human body. THC has much more effect on the brain and CBD has more effect on the body’s immune system, GI tract, and spleen. That is why marijuana, with a high concentration of THC, lead to feelings of euphoria and increased appetite, both of which are controlled by the brain. The effects of CBD on the body are not understood, but it has been proposed that it may affect inflammation, but this has not been proven. CBD is currently being promoted for pain relief, spasticity, epilepsy, and nausea relief.
Various preparations of natural and synthetic cannabis are available. Traditional cannabis can be smoked, vaporized, or eaten. Due to crossbreeding different strains of marijuana by growers the concentration of THC in cannabis has increased from 2% in 1980 to 12% in 2012. Many of the adverse effects of marijuana worsen with higher concentrations of THC, therefore several of the states that have legalized marijuana have restricted the content of THC in the marijuana. There are 13 such states with “low THC, high CBD” marijuana laws. Pennsylvania is not one of those states.
Cannabis Safety and Adverse Effects
As Interest in medical marijuana grows, it is important to understand the side effects and adverse effects associated with these drugs. Some of the most common adverse effects reported include dizziness, euphoria, confusion, disorientation, drowsiness, dry mouth, irritation of the nose and throat, paranoia, and nausea. As noted above, these adverse effects increase with the concentration of THC in the cannabis product. In addition, cannabis products have been shown to affect attention span and can cause impaired attention, delayed reaction time, short term memory impairment, and slowed motor control. This is of particular importance when operating motor vehicles. One recent study of nearly 50,000 subjects showed that cannabis use doubled the risk for major injury or fatality from motor vehicle accidents.
Patients should be especially careful of “full spectrum” products that combine several different cannabis products. Although individual ingredients may have undergone testing, the combination may have not, with unknown consequences. Patients with underlying cardiac disease are at risk for heart attacks. Chronic marijuana smoking can cause airway irritation and bronchitis, although lung cancer rates seem to be lower than for tobacco smokers.
Long term cannabis use can lead to addiction, and the addictive potential seems to increase the earlier in life an individual starts. Roughly 1 in 11 people in the general population exposed to cannabis becomes addicted, but this number increases to 1 in 6 when initial exposure starts before the age of 18. Cannabis also appears to exacerbate underlying mental illness, especially schizophrenia. Cannabis use also increases the risk of developing anxiety and depression later in life. These safety concerns pose a challenge when it comes to safe dosing, distribution, and monitoring of cannabis products legalized for medical use.
Cannabis use in Orthopedic Surgery
Since legalization of commercial cannabis sales in Colorado the self-reported use of cannabis has increased from 1% to 11% in patients undergoing total hip or knee replacement. This may be an indication that there are more marijuana users, or that they are more likely to report use without legal consequences. These patients are more likely to be young, male, currently smoke tobacco, and have a history of substance abuse. They are also more likely to report preoperative opioid use. There is extremely limited data on the effect of cannabis products in orthopedic patients. Most are not well controlled trials and rely on patients own self reporting of marijuana use. One study did show a lower death rate among patients undergoing hip and knee replacement and femur fracture surgery, although there was a higher rate of heart attack, heart failure, and stroke. Another large study showed that patients using Cannabis had a higher rate of re-operation after hip and knee replacement.
Many people wonder whether cannabis use can decrease opioid use after surgery. A study published in the Journal of Bone and Joint Surgery in 2018 showed that marijuana use after orthopedic trauma was associated with higher doses and longer duration of opioid use compared with non-cannabis users. An interesting study done on patients undergoing total knee replacement in Colorado showed that self-reported cannabis use gave no improvement in length of hospital stay, opioid use, readmission or reoperation, or overall success of surgery.
Medicinal cannabis has been reported to provide potential benefit to the orthopedic patient for their anti-inflammatory and pain-relieving properties. So far, the medical literature gives no definite support to these claims. Marijuana lies at the crossroads of medical curiosity and political policy which has prevented serious study of these drugs in a careful and Controlled manner. Perhaps that will change as more states legalize their use. If a clear benefit can be shown, then these drugs may provide a tool in the alleviation of our current opioid epidemic. Until then, especially in light of the potential complications associated with cannabis products, the orthopedic surgeon cannot recommend these products for acute pain relief.
– Dr. Zartman