Patellofemoral pain: one year results of a randomized trial comparing hip exercise, knee exercise, or free activity

Key points

1. 01No significant between-group differences in any primary or secondary outcome at 12 months
2. 02The whole cohort improved significantly from baseline to 12 months on the Anterior Knee Pain Scale (mean 65.3 to 77.7)
3. 03Exercise groups gained more muscle strength than the free-activity group, but this did not translate into better clinical outcomes
4. 04Compliance was high: 84% for knee group, 92% for hip group, 92% for control group
5. 05Results raise the question of whether guided exercise adds clinical benefit over patient education alone

How it was conducted

Design

Single-blind randomized controlled trial with 12-month follow-up (extended follow-up of a previously reported 3-month trial)

Participants

112 patients aged 16-40 years (mean 27.6 years) with clinical PFP for at least 3 months (mean 39 months) and pain at least 3/10 on VAS; recruited at a specialist Physical Medicine and Rehabilitation department in Norway

Groups

Hip-focused exercise (n=39), knee-focused exercise (n=37), or free physical activity/control (n=36); all groups received the same standardized patient education

Intervention

6-week supervised exercise program, 3 sessions per week (1 supervised, 2 home); 3 sets of 10-20 repetitions per exercise

Primary outcome

Anterior Knee Pain Scale (AKPS, 0-100; higher is better); MCID = 10 points

Follow-up

Outcomes assessed at baseline, 3 months, and 12 months

What they found

• No significant between-group differences in AKPS at 12 months: knee vs free activity -4.3 (95% CI -12.3 to 3.7); hip vs free activity -1.1 (95% CI -8.9 to 6.7); hip vs knee 3.2 (95% CI -4.6 to 11.0)
• AKPS improved significantly for the whole cohort from baseline (65.3) to 3 months (73.5) and further to 12 months (77.7), p=.01 for improvement from 3 to 12 months; effect size from baseline 0.81 (large)
• No significant between-group differences for usual pain, worst pain, kinesiophobia, knee self-efficacy, EQ-5D, or step-down test at 12 months
• Effect size for usual pain improvement from baseline to 12 months: 0.66 (moderate); worst pain: 0.70 (moderate)
• At 3 months, knee group showed significantly greater hip abduction strength vs control: 17.9 N (95% CI 2.7 to 33.2), p<0.05; hip group showed significantly greater knee extension strength vs control: 34.9 N (95% CI 3.9 to 65.9), p<0.05; these between-group strength differences were no longer significant at 12 months
• Additional treatment sought by 4 (12%) in knee group, 1 (3%) in hip group, and 6 (19%) in free activity group; difference was not statistically significant (p=.1)
• 88% of patients completed 12-month follow-up

Limitations

• Low recruitment rate (35%) may limit external validity and generalizability
• Study population had long pain duration and lower baseline AKPS compared to some studies, reflecting a specialist setting, which limits generalizability to primary care
• Control group physical activity level was not quantified during the intervention period
• Missing data for muscle strength testing at 12 months (14 patients unable to attend) limits the robustness of strength findings

Why it matters

For patients

Staying active with patient education may be just as effective as structured hip or knee exercise for kneecap pain, so people should not feel they must follow a specific program to recover.

For clinicians

Hip or knee exercise produces greater muscle strength gains than free activity, but neither type of exercise outperforms patient education combined with free activity on any clinical outcome at one year, which challenges the rationale for prescribing one exercise type over another.

For readers

This well-powered RCT provides moderate evidence that the type of exercise matters less than expected in patellofemoral pain, pointing toward patient education and self-directed activity as viable and possibly sufficient first-line strategies.