The Effectiveness of Tai Chi for Knee Osteoarthritis: An Overview of Systematic Reviews

Figures & data

Table 1 Search Strategy for PubMed Database

Query	Search Item
# 1	Osteoarthritis, Knee [Mesh]
# 2	Osteoarthritis, Knee [Title/Abstract]
# 3	Knee osteoarthritis [Title/Abstract]
# 4	Knee osteoarthritides [Title/Abstract]
# 5	Knee pain [Title/Abstract]
# 6	Knee joint osteoarthritis [Title/Abstract]
# 7	Knee arthritis [Title/Abstract]
# 8	Osteoarthritis of knee [Title/Abstract]
# 9	KOA[Title/Abstract]
# 10	Gonarthrosis [Title/Abstract]
# 11	Osteoarthrosis [Title/Abstract]
# 12	# 1 OR # 2–11
# 13	Tai Ji [MeSH]
# 14	Tai Chi [MeSH]
# 15	Tai Chi [Title/Abstract]
# 16	Chi, Tai [Title/Abstract]
# 17	Tai Ji Quan [Title/Abstract]
# 18	Ji Quan, Tai [Title/Abstract]
# 19	Quan, Tai Ji [Title/Abstract]
# 20	T’ai Chi [Title/Abstract]
# 21	Tai Chi Chuan [Title/Abstract]
# 22	Taiji [Title/Abstract]
# 23	Taijiquan [Title/Abstract]
# 24	Tai-ji [Title/Abstract]
# 25	Tai-chi [Title/Abstract]
# 26	Chi Quan, Tai [Title/Abstract]
# 27	# 13 OR # 14–26
# 28	Meta-analysis [Publication Type]
# 29	Meta-analysis [MeSH]
# 30	Systematic evaluation [Title/Abstract]
# 31	Systematic review [Title/Abstract]
# 32	Meta analysis [Title/Abstract]
# 33	Meta analyses [Title/Abstract]
# 34	# 28 OR # 29–33
# 35	# 12 AND # 27 AND # 34

Figure 1 Literature selection procedure.

Table 2 Basic Characteristics of the Included SRs

Author Year Ref	Country	Type of Included Studies	Number of RCT/Sample Size	Number of Search Databases (English/Chinese)	Intervention		Quality Assessment Tool	Outcome Measures	Overall Conclusions
					Treatment Group	Control Group
Lauche 2013^Citation27	Germany	RCT	5/252	(6/0)	TC	AC, NT, SC, AC+HE+SA, AC+HE+DA	Cochrane risk of bias tool	Short-term and long-term WOMAC Pain scale, Short-term and long-term WOMAC Physical function scale, Short-term and long-term WOMAC stiffness scale, Physical QQL, Mental QQL	This systematic review found moderate evidence for short-term improvement of pain, physical function and stiffness in patients with osteoarthritis of the knee practicing Tai Chi. Assuming that Tai Chi is at least short-term effective and safe it might be preliminarily recommended as an adjuvant treatment for patients with osteoarthritis of the knee. More high quality RCTs are urgently needed to confirm these results.
Xie 2015^Citation28	China	RCT	7/367	(4/4)	TC	HE, NT, HE+SA, HE+DA, HM	Cochrane risk of bias tool	WOMAC Pain scale, WOMAC Physical function scale, WOMAC stiffness scale, BA, Physical QQL, Mental QQL, WS, BMI, Knee extensor MF, Knee flexor MF	Tai Chi has been shown to improve joint pain, joint stiffness, joint function, walking speed and physical quality of life in KOA patients, and has a good safety profile. However, future multicentre, large sample randomized controlled studies with extended observation periods are needed to provide a more reliable basis for Tai Chi in the treatment of KOA.
Chang 2016^Citation29	China	RCT	11/508	(4/0)	TC	NT, HE, Interview	Jadad score	WOMAC pain scale, WOMAC physical function scale, WOMAC stiffness scale, 6MWT, safe, SCT	The review revealed that Tai Chi Chuan had beneficial outcomes for patients with knee osteoarthritis. The evidence-based results represented that it had small-to-moderate effects on body functions and structures, activities, and participation of physical component. However, there was insufficient evidence to support that Tai Chi Chuan had beneficial mental effect.
You 2021^Citation31	China	RCT	11/603	(6/0)	TC	AC	Cochrane risk of bias tool	6MWT, TUGT, WOMAC Physical Function Score	This meta-analysis provided evidence from 11 RCTs that Tai Chi could be an excellent physical training strategy for improving walking function and posture control in older adults with knee osteoarthritis. Assuming that Tai Chi is at least effective and safe in most areas, it can be used as an adjuvant and reliable physical training strategy for walking function upgrading and balance control improvements for older patients with knee osteoarthritis.
Hu 2021^Citation30	China	RCT	16/986	(7/2)	TC	NE, HE, PT, SC, NT	Cochrane risk of bias tool	WOMAC pain scale, WOMAC physical function scale, WOMAC stiffness scale, 6MWT, TUGT, BA, Physical QQL, Mental QQL, Depression, arthritis self-efficacy	Tai Chi exercise was beneficial for ameliorating physical and mental health of patients with knee osteoarthritis and should be available as an alternative non-pharmacological therapy in rehabilitation programmes.
Wang 2022^Citation32	China	RCT	16/917	(5/1)	TC	CT, HE, NT, HE+SA, CT+ exercise, Exercise, Interview	Cochrane risk of bias tool	WOMAC pain scale, WOMAC physical function scale, WOMAC stiffness scale, 6MWT, TUGT	Tai chi exercises are effective in improving pain, function, stiffness and enhancing exercise capacity in KOA patients. Future research should be strengthened for further validation of methodologies and harmonization of outcome indicators, etc.

Abbreviations: AC, attention control; NT, no treatment; SC, standard care; SA, social activities; HE, health education; DA, dietary advices; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index; QOL, Quality of life; HM, health management; BA, balance ability; WS, walking speed; MF, muscle force; SCT, stair climb test; 6MWT, 6-min walking test; TUGT, time up and go test; NE, no exercise; PT, physical therapy; CT, conventional treatment.

Table 3 Results of the AMSTAR 2 Tool

Author Year Ref	AMSTAR 2																Overall Quality
	Q1	Q2	Q3	Q4	Q5	Q6	Q7	Q8	Q9	Q10	Q11	Q12	Q13	Q14	Q15	Q16
Lauche 2013^Citation27	Y	N	N	PY	Y	Y	N	Y	Y	N	Y	N	Y	Y	N	Y	Critically low
Xie 2015^Citation28	Y	N	N	PY	Y	Y	N	Y	Y	N	Y	Y	Y	N	N	N	Critically low
Chang 2016^Citation29	Y	N	N	PY	Y	Y	N	Y	PY	N	Y	N	N	N	N	Y	Critically low
You 2021^Citation31	Y	N	N	PY	N	Y	N	Y	Y	N	Y	N	Y	Y	N	Y	Critically low
Hu 2021^Citation30	Y	N	N	PY	Y	Y	N	Y	Y	N	Y	N	Y	N	N	Y	Critically low
Wang 2022^Citation32	Y	N	N	PY	Y	Y	N	Y	Y	N	Y	Y	Y	Y	Y	N	Critically low
Number of Y (%)	6(100)	0(0)	0(0)	0(0)	5(83.7)	6(100)	0(0)	6(100)	5(83.3)	0(0)	6(100)	2(33.3)	5(83.7)	3(50)	1(16.7)	4(66.7)

Notes: Q1: Did the research questions and inclusion criteria for the review include the components of PICO? Q2: Did the report of the review contain an explicit statement that the review methods were established prior to the conduct of the review and did the report justify any significant deviations from the protocol? Q3: Did the review authors explain their selection of the study designs for inclusion in the review? Q4: Did the review authors use a comprehensive literature search strategy? Q5: Did the review authors perform study selection in duplicate? Q6: Did the review authors perform data extraction in duplicate? Q7: Did the review authors provide a list of excluded studies and justify the exclusions? Q8: Did the review authors describe the included studies in adequate detail? Q9: Did the review authors use a satisfactory technique for assessing the risk of bias (RoB) in individual studies that were included in the review? Q10: Did the review authors report on the sources of funding for the studies included in the review? Q11: If meta-analysis was performed did the review authors use appropriate methods for statistical combination of results? Q12: If meta-analysis was performed, did the review authors assess the potential impact of RoB in individual studies on the results of the meta-analysis or other evidence synthesis? Q13: Did the review authors account for RoB in individual studies when interpreting/discussing the results of the review? Q14: Did the review authors provide a satisfactory explanation for, and discussion of, any heterogeneity observed in the results of the review? Q15: If they performed quantitative synthesis did the review authors carry out an adequate investigation of publication bias (small study bias) and discuss its likely impact on the results of the review? Q16: Did the review authors report any potential sources of conflict of interest, including any funding they received for conducting the review?

Abbreviations: Y, Yes; PY, Partially Yes; N, No.

Table 4 Results of the ROBIS Tool

Author Year Ref	Phase 2				Phase 3
	1.Study Eligibility Criteria	2.Identification and Selection of Studies	3.Data Collection and Study Appraisal	4.Synthesis and Findings	Risk of Bias in the Review
Lauche 2013^Citation27	?	☹	☺	☹	☹
Xie 2015^Citation28	?	☹	☺	☹	☹
Chang 2016^Citation29	?	☹	☹	☹	☹
You 2021^Citation31	?	☹	?	☹	☹
Hu 2021^Citation30	?	☹	☺	☹	☹
Wang 2022^Citation32	?	☹	?	☹	☹

Notes: ☺=low risk of bias; ☹=high risk of bias; ?=unclear.

Figure 2 Risk of bias of the included SRs with ROBIS tool.

Table 5 Results of the PRISMA Assessment

Section/Topic	Items	Lauche 2013^Citation27	Xie 2015^Citation28	Chang 2016^Citation29	You 2021^Citation31	Hu 2021^Citation30	Wang 2022^Citation32	Compliance (%)
Title
	1.Title	Y	Y	Y	Y	Y	N	83.3%
Abstract
	2.Abstract	PY	PY	PY	PY	PY	PY	0%
Introduction
	3.Rationale	Y	Y	Y	Y	Y	Y	100%
	4.Objectives	Y	Y	Y	Y	Y	Y	100%
Methods
	5.Eligibility criteria	Y	Y	Y	Y	Y	Y	100%
	6.Information sources	PY	PY	PY	PY	PY	PY	0%
	7.Search strategy	N	N	N	N	N	N	0%
	8. Selection process	Y	Y	Y	N	Y	N	66.7%
	9.Data collection process	Y	Y	N	Y	Y	Y	83.3%
	10. Data items	PY	PY	PY	PY	PY	PY	0%
	11.Study risk of bias assessment	PY	PY	PY	PY	Y	PY	16.7%
	12.Effect measures	Y	Y	Y	Y	Y	Y	100%
	13.Synthesis methods	Y	PY	PY	PY	PY	Y	33.3%
	14.Reporting bias assessment	Y	Y	Y	N	Y	N	66.7%
	15.Certainty assessment	N	N	N	N	Y	N	16.7%
Results
	16.Study election	PY	PY	PY	PY	PY	PY	0%
	17.Study characteristics	Y	Y	Y	Y	Y	Y	100%
	18.Risk of bias within studies	Y	Y	N	Y	Y	Y	83.3%
	19.Results of individual studies	Y	Y	Y	Y	Y	Y	100%
	20.Results of syntheses	Y	PY	PY	PY	PY	Y	33.3%
	21.Reporting biases	Y	Y	N	N	N	Y	50%
	22.Certainty of evidence	N	N	N	N	Y	N	16.7%
Discussion
	23.Discussion	Y	Y	Y	Y	Y	Y	100%
Other information
	24.Registration and protocol	N	N	N	N	N	N	0%
	25.Support	Y	N	PY	PY	Y	PY	33.3%
	26.Competing interests	Y	N	Y	Y	Y	N	66.7%
	27.Availability of data, code and other materials	N	N	N	N	N	N	0%

Abbreviations: Y, yes (a complete report); PY, partially yes (a partially compliant report); N, no (no report).

Table 6 Results of the GRADE Tool

Author Year Ref	Outcomes	N/n	Pooled Effect Size	95% CI	I^2%	Limitations	Inconsistency	Indirectness	Imprecision	Publication Bias	Quality of Evidence
Lauche 2013^Citation27	Short-term WOMAC Pain scale	5/215	SMD=−0.72	−1.00, −0.44	0	−1^①	0	0	−1^③	0	L
	Long-term WOMAC Pain scale	2/73	SMD=−0.29	−1.06, 0.48	62	−1^①	−2^②	0	−1^③	0	CL
	Short-term WOMAC Physical function scale	5/215	SMD=−0.72	−1.01, −0.44	0	−1^①	0	0	−1^③	0	L
	Long-term WOMAC Physical function scale	2/71	SMD=−0.33	−0.95, 0.28	40	−1^①	−1^②	0	−1^③	0	CL
	Short-term WOMAC stiffness scale	5/215	SMD=−0.59	−0.99, −0.19	50	−1^①	−2^②	0	−1^③	0	CL
	Long-term WOMAC stiffness scale	2/71	SMD=0.06	−0.72, 0.83	62	−1^①	−2^②	0	−1^③	0	CL
	Physical QQL	2/84	SMD=0.88	0.42, 1.34	0	−1^①	0	0	0	0	M
	Mental QQL	2/84	SMD=0.35	−0.31, 1.01	54	−1^①	−2^②	0	−1^③	0	CL
Xie 2015^Citation28	WOMAC Pain scale	6/251	SMD=−0.73	−0.99, −0.14	39	−1^①	−1^②	0	−1^③	−1^④	CL
	WOMAC Physical function scale	6/249	SMD=−0.76	−1.02, −0.50	0	−1^①	0	0	−1^③	−1^④	CL
	WOMAC stiffness scale	6/249	SMD=−0.72	−1.24, −0.20	74	−1^①	−2^②	0	−1^③	−1^④	CL
	BA	3/116	SMD=0.42	−0.15, 1.00	58	−1^①	−2^②	0	−1^③	−1^④	CL
	Physical QQL	2/84	SMD=0.39	0.25, 1.16	64	−1^①	−2^②	0	−1^③	−1^④	CL
	Mental QQL	2/84	SMD=0.71	−0.35, 1.14	18	−1^①	0	0	−1^③	−1^④	CL
	WS	2/82	SMD=0.57	0.11, 1.02	0	−1^①	0	0	−1^③	−1^④	CL
	BMI	2/83	SMD=−0.13	−0.46, 0.21	0	−1^①	0	0	−1^③	−1^④	CL
	Knee extensor muscle force	2/99	SMD=0.23	−0.17, 0.63	35	−1^①	−1^②	0	−1^③	−1^④	CL
	Knee flexor muscle force	2/99	SMD=0.40	−0.46, 1.25	75	−1^①	−2^②	0	−1^③	−1^④	CL
Chang 2016^Citation29	WOMAC Pain scale	6/250	SMD=−0.41	−0.67, −0.14	80	−1^①	−2^②	0	−1^③	−1^④	CL
	WOMAC Physical function scale	5/207	SMD=−0.16	−0.44, –0.11	41	−1^①	−1^②	0	−1^③	−1^④	CL
	WOMAC stiffness scale	6/250	SMD=−0.20	−0.45, –0.05	59	−1^①	−2^②	0	−1^③	−1^④	CL
	6MWT	3/97	SMD=−0.16	−1.23, –0.90	82	−1^①	−2^②	0	−1^③	−1^④	CL
	Safe	2/134	SMD=−0.63	−0.98, −0.27	99	−1^①	−2^②	0	0	−1^④	CL
	SCT	2/53	SMD=−0.74	−1.34, −0.15	74	−1^①	−2^②	0	−1^③	−1^④	CL
You 2021^Citation31	WOMAC Physical Function Score	8/443	MD=−11.28	−13.33, −9.24	0	−1^①	0	0	−1^③	−1^④	CL
	6MWT	5/273	MD=46.67	36.91, 56.43	1	−1^①	0	0	−1^③	−1^④	CL
	TUGT	6/306	MD=−0.89	−1.16, −0.61	16	−1^①	0	0	−1^③	−1^④	CL
Hu 2021^Citation30	WOMAC Pain scale	14/877	SMD=−0.69	−0.95, −0.44	67	−1^①	−2^②	0	−1^③	−1^④	CL
	WOMAC Physical function scale	13/844	SMD=−0.92	−1.16, −0.69	57	−1^①	−2^②	0	−1^③	−1^④	CL
	WOMAC stiffness scale	12/769	SMD=−0.65	−0.98, −0.33	77	−1^①	−2^②	0	−1^③	−1^④	CL
	6MWT	6/426	SMD=0.55	0,10, 0.99	74	−1^①	−2^②	0	−1^③	−1^④	CL
	TUGT	5/225	SMD=−0.55	−0.82, −0.29	0	−1^①	0	0	−1^③	−1^④	CL
	BA	4/175	SMD=0.69	0.38, 0.99	39	−1^①	−1^②	0	−1^③	−1^④	CL
	Physical QQL	5/409	SMD=0.48	0.28, 0.68	24	−1^①	0	0	−1^③	−1^④	CL
	Mental QQL	5/409	SMD=0.26	0.06, 0.46	0	−1^①	0	0	−1^③	−1^④	CL
	Depression	3/319	SMD=−0.46	−0.68, −0.24	3	−1^①	−1^②	0	0	−1^④	CL
	Arthritis self-efficacy	4/352	SMD=0.27	0.06, 0.48	44	−1^①	−1^②	0	−1^③	−1^④	CL
Wang 2022^Citation32	WOMAC Pain scale	13/NA	SMD=−0.84	−1.10 −0.58	64	−1^①	−2^②	0	−1^③	0	CL
	WOMAC Physical function scale	13/NA	SMD=−0.88	−1.19, −0.57	74	−1^①	−2^②	0	−1^③	0	CL
	WOMAC stiffness scale	13/NA	SMD=−0.79	−1.09, −0.48	74	−1^①	−2^②	0	−1^③	0	CL
	6MWT	6/NA	SMD=0.60	0.11, 1.09	76	−1^①	−2^②	0	−1^③	0	CL
	TUGT	5/NA	SMD=−0.65	−0.91, −0.38	0	−1^①	0	0	−1^③	0	L

Notes: ①: The design of the experiment with a large bias in random, distributive hiding or blind; ②: The confidence interval overlaps less, the heterogeneity test P is Critically small, and the I² is larger;③: Confidence interval is not narrow enough;④: Asymmetric funnel plot or fewer studies are included and there may be greater publication bias.

Abbreviations: CL, critically low; L, low; M, moderate; H, high.

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