Hamstring Length in Patellofemoral Pain Syndrome

Objectives: To investigate whether there was a difference in hamstring length between patients with patellofemoral pain syndrome and healthy asymptomatic controls aged 18 to 35 years.

Design: A cross-sectional observational study measuring hamstring length in patients and asymptomatic controls.

Setting: Hospital physiotherapy department.

Participants: Two groups were tested; one group diagnosed with patellofemoral pain syndrome (mean age 27 years, n=11, six males, five females) and one group of asymptomatic controls (mean age 25 years, n=25, 13 males, 12 females).

Main Outcome Measures: Hamstring length was evaluated using the passive knee extension method to measure popliteal angle.

Results: The mean (standard deviation) values for hamstring length were 145.6 (8.7) degrees for patients with patellofemoral pain syndrome and 153.7 (10.1) degrees for the asymptomatic controls. The mean (95% confidence interval) difference between the groups was 8.0 (0.8 to 15.1) degrees , and analysis with a t-test revealed that this was statistically significant (P<0.05).

Conclusions: This study found that patients with patellofemoral pain had shorter hamstring muscles than asymptomatic controls. It is not clear whether this is a cause or effect of the condition. Further research is suggested to study how hamstring length changes with rehabilitation, and the relationship with pain.