Long-term effects of medical exercise therapy in patients with patellofemoral pain syndrome: results from a single-blinded randomized controlled trial with 12 months follow-up

Objectives: To evaluate the long-term effect of high-dose, high-repetition medical exercise therapy (MET) in patients with patellofemoral pain syndrome (PFPS).

Design: Follow-up study one year after completion of a randomized, controlled trial.

Setting: Follow-up testing in the primary healthcare physiotherapy clinics, where intervention was undertaken.

Participants: Twenty-eight patients with PFPS completed follow-up testing, fourteen in each group.

Interventions: The groups received three treatments per week for 12 weeks: high-dose, high-repetition MET for the experimental group, and low-dose, low-repetition exercise therapy for the control group.

Main outcome measures: Pain measured using a visual analogue scale (VAS: 0-10cm), and function measured using a step-down test (numbers of completed step-downs in 30 seconds) and the modified Functional Index Questionnaire (FIQ: 0 points indicates maximal disability, 16 points no disability).

Results: At baseline there were no differences between groups. After intervention, there were statistically significant (p<0.05) and clinically important differences between groups for all outcome parameters, also when adjusting for gender and duration of symptoms: -1.6 for mean pain [95% confidence interval (CI) -2.4 to -0.8], 6.5 for step-down test (95% CI 3.8 to 9.2), and 3.1 for FIQ (95% CI 1.2 to 5.0). At follow-up the differences between groups were maintained and even increased for mean pain and step-down with significant differences (p<0.05) between groups; -1.8 for mean pain (95% CI: -2.7 to -1.0) and 4.5 for step-down test (95%CI: 2.4 to 6.5). The difference between groups for FIQ at follow-up: 1.1 (95% CI: -1.1 to 3.3).

Conclusion: There appear to be long-term effects of high-dose, high-repetition MET in patients with PFPS with respect to pain and functional outcomes. One year after completed intervention the experimental group has continued to improve, while the control group has relapsed. Registered on http://www.clinicaltrials.gov (identifier: NCT01290705).