The authors have declared that no competing interests exist.
Performed the literature search and the data extraction: JHY WJG JS WXZ BWL. Responsible for the final approval of the version to be published: JHY WJG JS WXZ BWL LP. Conceived and designed the experiments: LP. Performed the experiments: JHY WJG JS WXZ BWL. Analyzed the data: LP JHY WJG JS WXZ BWL. Wrote the paper: LP JHY WJG JS WXZ BWL.
Whether Tai Chi benefits patients with osteoarthritis remains controversial. We performed a meta-analysis to assess the effectiveness of Tai Chi exercise for pain, stiffness, and physical function in patients with osteoarthritis.
A computerized search of PubMed and Embase (up to Sept 2012) was performed to identify relevant studies. The outcome measures were pain, stiffness, and physical function. Two investigators identified eligible studies and extracted data independently. The quality of the included studies was assessed by the Jadad score. Standard mean differences (SMDs) and 95% confidence intervals (CIs) were calculated and pooled using a random effects model. The change in outcomes from baseline was compared to the minimum clinically important difference.
A total of seven randomized controlled trials involving 348 patients with osteoarthritis met the inclusion criteria. The mean Jadad score was 3.6. The pooled SMD was −0.45 (95% CI −0.70–−0.20, P = 0.0005) for pain, −0.31 (95% CI −0.60–−0.02, P = 0.04) for stiffness, and −0.61 (95% CI −0.85–−0.37, P<0.00001) for physical function. A change of 32.2–36.4% in the outcomes was greater than the minimum clinically important difference.
Twelve-week Tai Chi is beneficial for improving arthritic symptoms and physical function in patients with osteoarthritis and should be included in rehabilitation programs. However, the evidence may be limited by potential biases; thus, larger scale randomized controlled trials are needed to confirm the current findings and investigate the long-term effects of Tai Chi.
Osteoarthritis (OA) is a leading cause of musculoskeletal pain and disability
Some published clinical trials of TC in patients with OA have shown inconsistent results for pain, stiffness, and physical function
A computerized search was performed in the PubMed and Embase databases (up to Sept 2012) for original research articles using the following keywords:
The following selection criteria were applied: (i) population, patients diagnosed with OA localized in any joints according to American College of Rheumatology criteria; (ii) intervention, Tai Chi, TaiJi Chuan, or Tai Chi Qigong with or without other treatment; (iii) comparison intervention, any type of control; (iv) outcome measures, pain, stiffness, and function assessed by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC); and (v) study design, RCT. Higher WOMAC scores indicate greater pain, stiffness, or physical disability.
For each study, we recorded the first author, year of publication, sample size, OA site, intervention duration and frequency, exercise time, intervention in the control population, and outcomes, including intergroup differences. To assess eligibility, the data and trial quality information were extracted from the papers selected for inclusion in the meta-analysis independently by two investigators (J Sun and WJ Gu). Extracted data were entered into a standardized Excel file and checked by a third investigator (JH Yan). Any disagreements were resolved by discussion and consensus. The outcome measures were pain, stiffness, and physical function.
The methodological quality of each trial was evaluated using the Jadad scale
All data were combined using Revman 5.1.0 (
The initial search yielded 45 relevant publications, of which 33 were excluded for duplicate studies and various reasons (reviews, non-randomized studies, or not relevant to our analysis) on the basis of the titles and abstracts (
RCT: randomized controlled trial.
The main characteristics of the seven RCTs included in the meta-analysis are presented in
Study, year | Patients No. (M/F); OA site | Age, Mean, yrs (I/C) | Study group (n) | Intervention (Tai Chi) group | Control group | Study design/Jadad score | |||
Duration (weeks)/Exercise Time | Frequency | Outcomes (WOMAC) | Intergroup differences | Intervention | |||||
Adler 2007 |
14 (1/13); Hip or knee | 70.8/72.8 | Tai Chi (8); Control (6) | 10/60 min | Once weekly | Pain | NS | Nonphysical recreational activity (Bingo) | RCT/3 |
Brismee et al., 2007 |
41 (7/34); Knee | 70.8/68.8 | Tai Chi (22); Control (19) | 12/40 min | Three times weekly for 6 weeks plus homebased Tai Chi for 6 weeks | PainStiffnessFunction | NSP<0.05P<0.05 | Attention control program | Single-blind, RCT/4 |
Fransen et al., 2007 |
97 (25/72); Hip or knee | 70.8/69.6 | Tai Chi (56); Control (41) | 12/60 min | Twice a week | PainFunction | NSP<0.05 | Waiting list | Double-blind, RCT/4 |
Lee et al., 2009 |
44 (3/41); Knee | 70.2/66.9 | Tai Chi (29); Control (15) | 8/60 min | Twice a week | PainStiffnessFunction | P<0.05NSNS | Waiting list | Single-blind, RCT/4 |
Song et al., 2003 |
43 (0/43); Knee | 64.8/62.5 | Tai Chi (22); Control (21) | 12/60 min | Three times a week | PainStiffness | P<0.05P<0.05 | Routine treatment | RCT/3 |
Song et al., 2009 |
69(0/69); Knee | 62.36/59.94 | Tai Chi (30); Control (39) | 24/60 min | Twice weekly for the first 3 weeks and once weekly for the next weeks | PainStiffnessFunction | NSNSP<0.05 | Self-help programme | RCT/3 |
Wang et al., 2009 |
40 (10/30); Knee | 63.0/68.0 | Tai Chi (20); Control (20) | 12/60 min | Twice a week | PainStiffnessFunction | P<0.05P<0.05NS | Wellness education and stretching | Single-blind, RCT/4 |
Note: M/F: Male/Female; OA: osteoarthritis; I/C: Intervention/Control; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; NS: not significant; RCT: randomized controlled trial.
All seven RCTs reported pain
Each block represents a study and the area of each block is proportional to the precision of the mean treatment effect in that study. The horizontal line represents each study's 95% confidence interval (CI) for the treatment effect. The centre of the diamond is the average treatment effect across studies, and the width of the diamond denotes its 95% CI.
Five RCTs reported stiffness
Five RCTs reported physical function
In addition, we performed a funnel plot for pain, stiffness, and physical function, which included 7 RCTs, 5 RCTs, and 5 RCTs, respectively. However, the limiting RCTs make it difficult to interpret the result of publication bias (
The major purpose of this meta-analysis was to update and critically evaluate the effects of TC training on arthritic symptoms and physical function in older patients with OA. Our meta-analysis suggests that 12-week TC significantly improves pain, stiffness, and physical function in patients with knee OA, which indicates that TC has benefits in the management of OA and should be available in rehabilitation programs as an alternative approach for patients with knee OA.
The primary goals in the management of OA are currently to alleviate arthritic symptoms, including pain and stiffness, maintain or improve joint mobility and quality of life, increase muscle strength, and minimize the disabling effects of OA
Our results showed that 12-week TC is effective at reducing pain and stiffness and improving physical function in patients with knee OA. Subgroup analyses suggested that 8–10 weeks of short-term TC can significantly improve pain and physical function, and 18–24 weeks of TC improves physical function. Theoretically, TC could be more effective over the long-term, but the positive effects of 12-week TC were not sustained after 6–12 weeks duration, which is consistent with previous findings
Recent efforts have suggested a minimal clinically important difference (MCID) for WOMAC scores from both pharmacological and rehabilitation trials. Changes of 20–25% in the WOMAC score are considered to be clinically relevant
Our results are similar to the latest SR
The possible mechanisms responsible for the beneficial effects of TC that differ from other forms of exercise are still unclear. TC harmonizes yin-yang and promotes homeostasis between body and mind. TC is a lower intensity exercise of flowing circular movements, balance and weight shifting, deep breathing regulation and meditation, and visualization, and focuses on internal awareness
We found that most studies lacked other objective outcome measures, including exercise performance (e.g., 6-min walk distance), quality of life, body mass index, muscle strength, immune function, and survival, which would result in more reliable and convincing evidence of the effects of TC in patients with OA. Furthermore, comparing TC with general forms of exercise, such as jogging and motion or flexibility exercises, would be better, but this method has not seen much use in clinical research. Therefore, focusing on these additional interesting clues may be useful for future research on the topic. In addition, future researchers should attempt to understand the relationships among impairment, functional limitations, and disability.
Finally, we found no significant side effects or adverse events associated with TC, and participants had relatively high adherence in most studies, indicating that TC is safe and has satisfactory compliance. Given no special setting, no additional costs, independence from weather conditions, and multiple benefits to the body, TC should be an alternative to other exercise training and be incorporated into rehabilitation programs as a potential non-pharmacological treatment for patients with OA.
This study had numerous limitations. First, our analysis is based on seven RCTs, all of which had a small sample size. Overestimation of the treatment effect is more likely in smaller trials compared to larger trials. Although we performed a funnel plot for the outcomes, the limiting RCTs make it difficult to interpret the result of publication bias. Moreover, a major limitation of our subgroup analyses is that some (<12 and >12 weeks) are based only on 2 to 3 studies; thus, the conclusions about the duration of TC exercise should be interpreted with caution. Next, the targeted population varied greatly (e.g., patients of different gender, ethnicity, and duration of OA). The adopted TC protocols differed. These factors may have a potential impact on our results. Finally, some missing and unpublished data may lead to bias.
In summary, the positive findings of this study suggest that 12-week TC has beneficial effects on the management of knee OA, including reduced pain and stiffness and improved physical function. As an alternative, effective, inexpensive, and accessible approach, TC should be available in rehabilitation programs. However, given the heterogeneity among study designs and small RCTs, additional larger scale RCTs are needed to substantiate the current findings and investigate the long-term effects of TC in patients with knee OA.
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