A recent medical study showed that practicing Taiji is equally effective versus doing physical therapy for knee osteoarthritis.  Knee osteoarthritis, commonly known as wear-and-tear arthritis of the knee, is a condition in which the natural cushioning between joints in the knee — cartilage — wears away. When this happens, the bones of the knee joints rub more closely against one another with less of the shock-absorbing benefits of cartilage, resulting in pain, swelling, stiffness, and decreased ability to move. More than 27 million people in the U.S. have osteoarthritis, with the knee being one of the most commonly affected areas. Women are more likely to have osteoarthritis than men.
With respect to osteoarthritis, reference 1 states that “Currently there is no effective medical treatments. Nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen are commonly used to treat osteoarthritis but often fail to relieve symptoms and may cause serious adverse effects. Physical therapy, a globally recommended element of the standard care regimen for knee osteoarthritis produces moderate benefits for pain and physical functioning, but data on psychological well being and durability effects are limited.”
Previous studies of Taiji already showed promise that it can reduce pain and improve physical and psychological health for patients with rheumatoid arthritis and fibromyalgia, and knee osteoarthritis. The current study compares a group practicing Taiji and another group undergoing physical therapy. The results show that both approaches produced beneficial effects in treating knee osteoarthritis, but the Taiji group had significanly greater improvements in depression and the physical component of quality of life (i.e., overall health improvement).
Methodology: Recruited participants have knee osteoarthritis and were randomly assigned to either the Taiji Group or the Physical Therapy Group. The Taiji Group practices 2 times per week for 60-minute sessions for 12 weeks, or a total of 120 minutes per week . The Physical Therapy Group does physical therapy 2 times per week for 30-minute sessions for 6 weeks , and is followed by 6 weeks of rigorously monitored home exercise consisting of 30-minute sessions 4 times per week, or a total of 120 minutes per week. During the first 6 weeks, the Physical Therapy participants were also encouraged to perform exercises at home . The study actually extended beyond 12 weeks to 52 weeks; more on the extended benefits will be reported later in this article.
There were 204 participants. The mean age was 60 years, 70% were women. The racial/ethnic composition was diverse with 53% white. All the participants were verified to suffer knee osteoarthritis from the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) standardized test. For example, on a scale of 0-500 for the WOMAC pain subscale score, the average score for the Taiji Group was 254.8, and for the Physical Therapy Group was 252.9. Higher score means more pain.
Results: WOMAC standardized tests were administered before the beginning and after the end of the 12-week supervised exercise period. The improvements for both groups were significant from various indices, observations, and participants’ own feeling. For example, the average WOMAC pain subscale score for the Taiji Group was reduced from 254.8 to 87.59, and for the Physical Therapy Group was reduced from 252.9 to 109.89 The improvements for both groups were significant, but differences in the two groups relative to the WOMAC pain subscale score is not that significant.
To gauge the longer-term effectiveness of the treatments, the study also asked the participants to continue their exercises for another 40 weeks, or a total of 52 weeks. For the Taiji Group, they were asked to practice Taiji at home for at least 20 minutes per day, with the aid of provided homework materials. For the Physical Therapy Group, they were asked to continue their physical therapy exercises at home for 30 minutes, 4 times per week. WOMAC tests were also done at the end of 24 weeks and 52 weeks. The study results showed that the health benefits of both groups lasted for the longer periods. For example, the average WOMAC pain scale score for the Taiji Group was 96.2 at 24 weeks and 116 at 52 weeks, still substantially lower than the original baseline score of 254.8. Similarly, the average WOMAC pain scale score for the Physical Therapy Group was 128.6 at 24 weeks and 131.9 at 52 weeks, still substantially lower than the original baseline score of 252.9.
The study showed that in terms of physical health around the knee such as pain level, treatment with Taiji practice or physical therapy exercises showed similar improvements, and the difference between the two methods of treatment was not statistically significant. However, in terms of depression, there was a difference. The study used the Beck Depression Inventory-II (BDI-II) score to assess depression, with the score ranging from 0 to 63, the higher the score the more severe is the depression.  The average BDI-II score for the Taiji Group was 7.8 for the original baseline score and 5.6 at 12 weeks, a statistically significant reduction. But for the Physical Therapy Group, the average BDI-II score was 7.5 for the original baseline score and 8.0 at 12 weeks, an actual increase but probably statistically not significant. For the longer periods. For the Taiji Group, the average BDI-II score was 6.1 at 24 weeks, and 6.7 at 52 weeks, still significant reduction. For the Physical Therapy Group, the average BDI-II score was 7.7 at 24 weeks, and 7.5 at 52 weeks, meaning essentially no change in this depression index.
The study had 3 Taiji teachers, and the study showed that the results were independent of the particular Taiji teacher. Therefore, the positive results are more due to the basic Taiji principles and exercises, and not due so much to a particular instructor. Relative to Taiji, physical therapy exercises are more standardized, so this should not be a major concern for physical therapy treatment
Summary: This study shows that doing Taiji exercises can provide comparable improvements as compared to Physical Therapy exercises in the treatment of knee osteoarthritis in terms of the physical health related to the knee. There are significant improvements for both methods, and the improvements remain for longer periods (up to 52 weeks in this study) if the exercises are continued. However, doing Taiji exercises has a positive impact in terms of depression that may result from knee osteoarthritis, whereas doing physical therapy exercises does not seem to help with depression that may result from knee osteoarthritis.
This probably suggests that the exercises from Taiji and Physical Therapy both improve the physical parts of various muscles, tendons, ligaments, cartilage, bones, blood circulation, etc. related to the knee, but the involvement of the mind and the meditative aspects of Taiji may be contributing to the mental health of the practitioner that could lead to a reduction in depression. Besides depression, the study also stated that the Taiji Group had significantly greater improvements in the physical component of quality of life, i.e., overall health. My interpretation of this statement is that Taiji can improve the body toward certain ailment, e.g., knee osteoarthritis, but it can also improve the body toward other ailments, and the improvement is both physical and mental, i.e., improvement in overall health, or quality of life.
 C. Wang, et. al., Comparative Effectiveness of Tai Chi Versus Physical Therapy for Knee Osteoarthritis: A Randomized Trial, Annals of Internal Medicine, 2016; 165(2):77-86
 A short summary of this study can be found in the article “Study Shows Tai Chi and Physical Therapy Were Equally Helpful for Knee Osteoarthritis”: https://nccih.nih.gov/research/results/spotlight/tai-chi-knee-osteoarthritis_2016.
 The Taiji participants were also instructed to practice Taiji at home for at least 20 minutes per day, but the article did not say how much did the Taiji participants actually practice at home during those 12 weeks. The Taiji style that was used in this study is the Yang style.
 During the first 6 weeks, the Physical Therapy participants’ sessions totaled only 60 minutes per week versus the 120 minutes per week of the Taiji participants, but during those 60 minutes the Physical Therapy participants were worked on by physical therapists, whereas the Taiji participants were doing Taiji exercises on their own although under the guidance of a Taiji instructor. So the difference in total time may not be that significant.
 The Physical Therapy participants were also encouraged to perform exercises at home during those first 6 weeks, but the article did not say how much did the Physical Therapy participants actually practice at home during those 6 weeks.
 The Beck Depression Inventory (BDI, BDI-1A, BDI-II) is one of the most widely used psychometric tests for measuring the severity of depression. See, e.g., https://en.wikipedia.org/wiki/Beck_Depression_Inventory.