A Systematic Review with Meta-analysis of the Association between Changes in Muscle Strength and Clinical Outcome Changes in Patellofemoral Pain.
Guilherme S Nunes, Matheus Weide Solner, Jênifer de Oliveira et al.
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In 30 seconds
This systematic review and meta-analysis examined whether changes in muscle strength were associated with concurrent changes in pain or physical function in people with patellofemoral pain. It included 82 randomised trials involving 4023 participants and used a two-stage structural equation modelling approach. Strength improvements across several knee and hip muscle groups were significantly associated with reduced self-reported pain; improvements in five muscle groups were also associated with better self-reported function. Evidence certainty ranged from low to high, depending on the outcome and muscle group. The findings indicate associations, not proof that strength gains caused clinical improvement.
Key findings
- Strength gains were associated with less pain for seven muscle groups; for hip abductors, the association was r = - 0.91, β = - 0.31.
- Strength gains in knee extensors, knee flexors, hip abductors, hip adductors and hip internal rotators were associated with improved function.
- For hip internal rotators, strength change and function change were associated at r = 0.98, β = 0.06.
Why it matters
The review links changes in lower-limb strength with changes in two clinically important outcomes in patellofemoral pain: pain and physical function. This supports the relevance of assessing strength alongside symptoms and function when evaluating rehabilitation outcomes. However, the associations do not establish that strength improvement itself produces symptom or functional improvement.
What to keep in mind
The findings are associations between concurrent changes in trials and do not establish causation. Evidence certainty varied from low to high across outcomes and muscle groups.