Effectiveness of isolated hip exercise, knee exercise, or free physical activity for patellofemoral pain

Key points

1. 01No between-group differences in pain, function, quality of life, or kinesiophobia at 3 months across all three groups
2. 02All three groups improved meaningfully on the Anterior Knee Pain Scale (mean whole-cohort improvement 7.6 points, 95% CI 5.6-9.6)
3. 03Hip and knee exercise groups gained more muscle strength than the free-activity group, but this did not translate into better clinical outcomes
4. 04Compliance was high (88% overall), so the null result is not explained by poor adherence
5. 05Patient education emphasizing low fear of movement was delivered to all groups, possibly driving the shared improvement

How it was conducted

Design

Single-blind randomized controlled trial (CONSORT-compliant), registered NCT02114294

Participants

112 patients aged 16-40 years (mean 27.6 years) with PFP for more than 3 months (mean 39 months), confirmed by MRI to exclude other pathology

Groups

Hip-focused exercise + education (n=39), knee-focused exercise + education (n=37), free physical activity + education (n=36)

Intervention duration

6 weeks, 3 sessions per week (1 supervised, 2 home); followed up at 6 weeks and 3 months

Primary outcome

Anterior Knee Pain Scale (AKPS, 0-100) at 3 months; minimal clinically important difference = 10 points

Secondary outcomes

VAS pain, Tampa Scale for Kinesiophobia, Knee Self-efficacy Scale, EQ-5D-5L, step-down test, isometric hip and knee strength

What they found

• Primary outcome AKPS between-group differences at 3 months: knee vs control 0.2 (95% CI -5.5 to 6.0); hip vs control 1.0 (95% CI -4.6 to 6.6); hip vs knee 0.8 (95% CI -4.8 to 6.4); overall P=.90
• Whole-cohort AKPS improved from 65.9 to 73.5 at 3 months (mean difference 7.6, 95% CI 5.6-9.6; P<.001); effect size Cohen d=0.74
• No significant between-group differences at 3 months for usual pain, worst pain, step-down, EQ-5D-5L, EQ-VAS, knee self-efficacy, or kinesiophobia
• Hip abduction strength (knee vs control) was significantly greater at 6 weeks (difference 13.6 N, 95% CI 2.2-24.9; P=.01) and 3 months (17.9 N, 95% CI 2.7-33.2; P=.02)
• Knee extension strength (hip vs control) was significantly greater at 6 weeks (40.0 N, 95% CI 14.7-65.3; P=.001) and 3 months (34.9 N, 95% CI 3.9-65.9; P=.02)
• Compliance: 88% overall (hip 92%, knee 84%, control 92%); dropout rate 7%

Limitations

• Follow-up was only 3 months, so long-term differences between approaches cannot be excluded
• Activity level of the free-activity control group was not quantifiable, limiting interpretation of what the control group actually did
• A large proportion of referred patients were excluded, which may reduce generalizability to broader clinical populations
• Improvement in all groups may partly reflect natural history or regression to the mean rather than treatment effect

Why it matters

For patients

Patients with patellofemoral pain can expect similar short-term improvement whether they follow a structured hip or knee exercise program or simply stay active, as long as they also receive good education about their condition.

For clinicians

Isolated hip or knee exercise programs provided no additional benefit over active self-management plus patient education at 3 months; clinicians should ensure the educational component addresses kinesiophobia and may consider tailoring exercise to individual deficits rather than defaulting to a single exercise type.

For readers

This adequately powered RCT challenges the assumption that specific exercise type is the main driver of improvement in PFP, pointing instead to shared elements such as patient education and staying physically active as potentially sufficient for short-term benefit.