Physical Therapy for Osteoarthritis Knee Pain

Is physical therapy (PT) effective for osteoarthritis (OA) knee pain in adults?

Exercise therapy with strength, aerobic, or aquatic PT may decrease pain due to knee OA in the short term (6–18 weeks). Improvements may persist for 1 year but typically are diminished by 18 months. (Strength of Recommendation [SOR]: B, systematic review of randomized controlled trials [RCTs], individual RCT.) PT results in greater pain relief for 1 year than glucocorticoid knee injections. (SOR: B, RCT.)

A 2019 systematic review and meta-analysis of 77 RCTs (N = 6,472) compared several exercise interventions with usual care for the treatment of hip and knee OA.¹ These interventions focused on strength and aerobic training exercises. Analysis of the aggregated RCTs showed a moderate effect on overall pain at 8 weeks with exercise compared with usual care (38 trials; n = 2,415; effect size = 0.54; 95% CI, 0.40 to 0.67). The effect was greater for knee pain (55 trials; n = 3,750; effect size = 0.64; 95% CI, 0.51 to 0.78) than hip pain (eight trials; n = 703; effect size = 0.17; 95% CI, –0.17 to 0.51). The effect decreased gradually over several months until there was no statistical difference between exercise and usual care at 18 months.

Using a multivariate meta-regression, this review showed that trials with participants younger than 60 years found greater reductions in pain at 8 weeks with exercise interventions (12 trials involved participants younger than 60 years; n = 591; effect size = 1.32; 95% CI, 0.79 to 1.86, whereas 57 trials involved participants 60 years and older; n = 4,681; effect size = 0.44; 95% CI, 0.34 to 0.55).

A 2022 systematic review and meta-analysis compared a variety of outcomes with aquatic PT vs nonaquatic PT (ie, land-based exercise, usual care, education, no intervention) for knee OA treatment.² A subgroup of this review (five trials; n = 351) examined Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) knee pain scores. This score measures pain, stiffness, and function on a scale of 0 to 240 points, with higher scores indicating more severe symptoms. The duration of interventions ranged from 6 to 18 weeks. In a sub-analysis of RCTs in which knee pain was measured before and after treatment, there were significantly lower WOMAC pain scores in the aquatic PT groups compared with the nonaquatic PT groups (standardized mean difference = –1.09; 95% CI, –1.97 to –0.21).

A 2021 RCT of adults 50 years and older (N = 337) evaluated the effects of high-intensity strength training on knee pain.³ Participants had self-reported disability from knee OA and mild to moderate radiographic evidence of OA in at least one knee. They were randomized into three treatment groups. Two groups participated in 60-minute strength training sessions three times per week. One of the strength training groups completed the exercises at high intensity, meaning fewer repetitions in each of three sets (ie, 4–8 repetitions) with heavier weights. The other strength training group completed the exercises at low intensity, with 15 repetitions of each exercise using lighter weights. The third group attended 60-minute workshops biweekly on healthy living for the first 6 months, then weekly thereafter.