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.