Hot Topic | Osteoarthritis and Physical Therapy

Knee osteoarthritis (OA) is a leading cause of chronic pain and disability in the middle- an older-age population. There are over 600 million worldwide with OA, the knee being the most affected joint. In the absence of effective non-opioid pharmacologic therapies for knee pain, OA remains a key driver of the opioid epidemic and healthcare costs  continue to climb due to rapidly increasing rates of joint replacement surgeries.  

Individuals diagnosed with knee OA (or OA of any joint) should be encouraged to meet the ACSM guidelines for aerobic and strength exercise, as described in the previous month‘s Hot Topic Commentary. However, despite the benefits of exercise, people with OA remain less active than people without OA. Inactivity and insufficient engagement in structured exercise fuels a vicious cycle of further pain and disability and can also increase the risk of early mortality. There are several reasons for low exercise engagement among people with OA. These include, but are not limited to, negative perceptions of exercise, negative prior experiences with exercise, difficulty interpreting or implementing exercise guidelines, and insufficient support from healthcare providers. Another factor is poor utilization of physical therapy services, this being particiularly important for OA individuals given exercise and education are typically included as part of therapy care for this population. Instead, in real-world practice, less effective and potentially harmful pharmacologic therapies, such as oral painkillers and steroid and hyaluronic acid injections, are the most used first line therapies for people with knee OA.

Educating patients, providers, and payors about the real-world benefits of physical therapy care could potentially improve referral to and utilization of physical therapy care for people with knee OA. However, while the importance of general exercise and education has been studied extensively in controlled clinical trials, less is known about real-world effectiveness of physical therapy care for people with chronic knee pain.

We tackled this gap in a series of studies where we used real-world insurance claims data to examine if the timing of starting physical therapy care after knee OA diagnosis can impact future use of potentially harmful opioids or injectable therapies like corticosteroids. In these studies, we analyzed data from over 67,000 people with newly diagnosed knee OA. We found that the sooner a person starts receiving physical therapy after a diagnosis, the lower their risk of future use of opioids or injectable therapies. Conversely, we found the greater the delay to initiation of physical therapy care, the greater the future risk.

In another study, we also examined whether physical therapy care before joint replacement surgery and after surgery can impact future opioid use in people with knee OA. This is important because a small but significant proportion of people who undergo joint replacement surgeries continue to experience pain and are at risk of becoming chronic opioid users. We observed that receiving pre-operative physical therapy care was related to reduced risk of long-term opioid use after surgery. Also, receiving six or more sessions of physical therapy care after surgery, and initiation of physical therapy care within 30 days of surgery, were related to lower risk of long-term opioid use in the future.

These data provide compelling evidence that physical therapy care, if provided early and for optimal duration, can reduce the utilization of opioids and other harmful therapies in people with chronic knee pain. Similarly, use of physical therapy care before and after knee replacement surgery is also protective. It is important to note that in these studies, we only included people who did receive physical therapy care because of the nature of insurance claims data; we did not compare people who did and did not receive physical therapy care.

As discussed in last month’s Hot Topic Commentary, consistent engagement with exercise is more important than any particular exercise for managing OA-related pain and disability. It is not uncommon for people with knee OA to experience some pain and discomfort when starting exercise. We recently reported that some pain during exercise may actually yield beneficial analgesic effects for people with knee OA, helping healthcare providers appropriately educate patients about self-monitoring for symptoms and strategies to modify exercise dose as needed.

Although exercise is recommended for all patients diagnosed with OA, research shows that not all patients experience improvements. Indeed, only about 40-60% of participants receiving exercise interventions are typically identified as being responders, and have meaningful improvements in pain. This does not necessarily suggest that exercise may not be appropriate for all patients. Rather, it is possible that some patients may need adjunctive therapies, in addition to exercise, to more comprehensively address their clinical condition. For instance, chronic pain due to OA commonly co-occurs with fatigue, sleep disturbances, and psychological impairments including depressed mood, anxiety, fear of movement, and catastrophizing behaviors. There is also evidence that the ability of the nervous system to transmit and regulate pain sensations can be deficient in people with chronic pain. Healthcare providers should be aware of the possibilities of these additional impairments being present and when needed, provide appropriate referrals, for example to psychologists or mind-body therapists.

OA is a public health challenge and pharmacologic treatment options remain suboptimal. Increased utilization of exercise- and education-based interventions as first-line therapies is necessary to improve clinical care of people experiencing OA-related pain and disability.

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