Study design: Case control design.
Objectives: To investigate whether differences exist in lower extremity muscle strength and soft tissue length between patients with patellofemoral pain syndrome (PFPS) and age- and gender-matched control subjects.
Background: Based on our clinical experience and emerging data, impairments such as muscular weakness surrounding the hip and limited flexibility of key lower extremity muscles may be important impairments to consider in the conservative management of PFPS.
Methods and measures: Thirty patients with PFPS and 30 age- and gender-matched controls without PFPS (17 females and 13 males in each group) participated in the study. Data were collected during 1 testing session by an examiner not blinded to group assignment. Demographic, health history, physical activity levels, and pain and function were assessed using patient-completed measures. Physical examination measures included assessment of hip external rotation strength, hip abduction strength, length of the iliotibial band/tensor fascia lata complex, gastrocnemius length, soleus length, and quadriceps and hamstrings muscles length.
Results: Patients with PFPS demonstrated significantly less flexibility of the gastrocnemius, soleus, quadriceps, and hamstrings compared to healthy control subjects. No differences existed in flexibility of the iliotibial band/tensor fascia lata complex and strength of the hip external rotators and abductors. Multivariate stepwise discriminant analysis identified gastrocnemius length, hip abduction strength, and soleus length as being able to distinguish between patients with PFPS and healthy individuals without PFPS.
Conclusion: This study suggests that further research is warranted regarding the association of these impairments of muscle strength and soft tissue length in patients with PFPS.