Exercise Therapy for Knee Osteoarthritis: A Systematic Review and Network Meta-analysis

Abstract

Background: Exercise is an effective nonpharmaceutical therapy for knee osteoarthritis (KOA).

Purpose: To identify the most effective type of exercise therapy for KOA with regard to pain, stiffness, joint function, and quality of life.

Study design: Systematic review; Level of evidence, 3.

Methods: The PubMed, Web of Science, Embase, and Cochrane Library databases were searched, from inception to April 4, 2022. Included were randomized controlled trials that assessed the efficacy on KOA among 5 different exercise therapy groups (aquatic exercise [AE], stationary cycling [CY], resistance training [RT], traditional exercise [TC], and yoga [YG]) and compared with the control group. Outcomes among the groups were assessed with the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), 6-minute walk test (6-MWT), visual analog scale (VAS) for pain, and Knee injury and Osteoarthritis Outcome Score (KOOS); weighted mean differences (WMDs) and 95% confidence intervals were calculated. Network meta-analyses comparing outcomes between all groups and with controls were performed, and group rankings were calculated using the surface under the cumulative ranking curve (SUCRA).

Results: A total of 39 studies (N = 2646 participants) were included. Most of the studies failed to blind participants and researchers, resulting in a high risk of performance bias. Significantly worse WOMAC-Pain scores were seen in controls compared with all exercise interventions except AE (WMD [95% CI]: CY, -4.45 [-5.69 to -3.20]; RT, -4.28 [-5.48 to -3.07]; TC, -4.20 [-5.37 to -3.04]; and YG, -0.57 [-1.04 to -1.04]), and worse scores were seen in controls compared with YG regarding WOMAC-Stiffness (WMD, -1.40 [95% CI, -2.45 to -0.34]) and WOMAC-Function (WMD, -0.49 [95% CI, -0.95 to -0.02]). According to the SUCRA, CY was the most effective for improving WOMAC-Pain (80.8%) and 6-MWT (76.1%); YG was most effective for improving WOMAC-Stiffness (90.6%), WOMAC-Function (77.4%), KOOS-Activities of Daily Living (72.0%), and KOOS-Quality of Life (79.1%); AE was the most effective regarding VAS pain (77.2%) and KOOS-Pain (64.0%); and RT was the most effective regarding KOOS-Symptoms (84.5%).

Conclusion: All 5 types of exercise were able to ameliorate KOA. AE (for pain relief) and YG (for joint stiffness, limited knee function, and quality of life) were the most effective approaches, followed by RT, CY, and TC.

Keywords: exercise therapy; knee osteoarthritis; network meta-analysis; systematic review.

Figure 1.

Flowchart of study selection.

Figure 2.

(A) Overall risk of bias of the included studies. For each domain evaluated, the percentages of low, medium, and high risk of bias were as follows: randomization sequence generation (79%, 19%, and 2%), allocation concealment (52%, 48%, and 0%), blinding of participants and personnel (32%, 15%, and 53%), blinding of outcome assessment (24%, 33%, and 43%), incomplete outcome data (74%, 17%, and 9%), selective reporting (97%, 3%, and 0%), and other source of bias (24%, 6%, and 0%). (B) Risk of bias for each included study. *Reference 39. **Reference 40.

Figure 3.

Forest plots (left), cumulative probability graphs (middle), and network diagrams (right) for (A) WOMAC–Pain, (B) WOMAC-Stiffness, and (C) WOMAC-Function. On the forest plots, for treatment effect 1 vs 2, a negative WMD favors 1 and a positive WMD favors 2. On the network diagrams, the size of each node is weighted based on the number of participants receiving a certain intervention, and the thickness of the lines connecting 2 nodes is weighted according to the number of studies that applied the connected interventions. A and AE, aquatic exercise; B and CG, health education (control); C and CY, stationary cycling; D and RT, resistance training; E and TC, traditional exercise; F and YG, yoga; WMD, weighted mean difference; WOMAC, Western Ontario and McMaster University Osteoarthritis Index.