Effects of lower-limb active resistance exercise on mobility, physical function, knee strength and pain intensity in patients with total knee arthroplasty: a systematic review and meta-analysis.

After knee replacement surgery, pain often eases but muscle strength and everyday function can stay reduced for a long time. This review asked whether a specific type of rehabilitation, active resistance exercise where patients actively work muscles against resistance, helps more than conventional exercise programs without this component. Pooling 14 randomized controlled trials involving 880 patients, the researchers found that active resistance exercise was associated with statistically significant improvements in walking speed, a timed mobility test, knee extension and flexion strength, knee bending range of motion, and pain scores compared with conventional exercise, measured right after the intervention ended. However, not every outcome showed a clear advantage: a six-minute walk test, a stair-climbing test, and knee extension range of motion showed no statistically significant difference between groups.

This mixed pattern, some outcomes improving and others not, is worth noting rather than ignoring. The main limitation is that these are immediate post-intervention results from a modest evidence base, so how durable these benefits are and how they translate to longer-term recovery remains unclear.

If you've had or are considering knee replacement surgery, you may know that pain often improves quickly, but regaining strength and confident movement can take much longer. This review looked at a specific style of rehabilitation exercise, called active resistance exercise, where you actively push or pull against resistance to build muscle strength, and compared it to more standard rehab exercises used after knee replacement. Across a pool of 14 trials with 880 patients, the researchers found that people doing this resistance-based exercise showed better results right after finishing their program in several areas: walking speed, a timed up-and-go mobility test, knee muscle strength, knee bending flexibility, and reported pain.

However, some other measures, like a six-minute walk test, a stair-climbing test, and knee straightening flexibility, did not show a clear difference between the groups. This is encouraging but not definitive. These results reflect what happened immediately after the exercise programs ended, not months or years later, and the overall evidence base, while pooling many studies, is still moderate in size.

It's reasonable to view this as a promising direction rather than a settled answer.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This meta-analysis informs the ongoing question of what active resistance exercise contributes to postoperative rehabilitation after total knee arthroplasty, specifically whether it outperforms conventional exercise programs that lack this resistance component. Pooling 14 randomized controlled trials and 880 patients, the authors report statistically significant between-group improvements favoring active resistance exercise for maximal walking speed, Timed Up and Go, knee extension power, knee flexion power, flexion range of motion, and pain intensity (VAS), all measured immediately post-intervention.

These findings support a role for resistance-based loading in addressing persistent postoperative strength and functional deficits, though the effect sizes vary and some confidence intervals are wide. Importantly, three outcomes, six-minute walk test, stair climb test, and extension range of motion, showed no statistically significant difference between groups, indicating the benefit of active resistance exercise is not uniform across all functional measures; this inconsistency should temper broad claims of superiority. The review does not establish long-term durability of these effects, since all reported results are immediate post-intervention comparisons, nor does it detail adverse events, which the abstract does not mention.

Heterogeneity in exercise protocols, comparator programs, and patient populations across the 14 trials also limits how confidently these pooled estimates generalize to any single clinical pathway.