Comparison of the Quadriceps Muscle Thickness and Function between Patients with Patellofemoral Pain Syndrome and Healthy Subjects using Ultrasonography: An Observational Study

Objectives: To compare the thickness and function of the quadriceps muscle in subjects with and without patellofemoral pain syndrome (PFPS) by ultrasonography.

Methods: Patients diagnosed with PFPS were included in the study. To measure the thickness of the rectus femoris (RF), vastus medialis longus and oblique (VML, VMO), vastus lateralis (VL) and vastus intermedius (VI), the ultrasonography was employed in rest and normal contraction modes and also the % rest-thickness normal as muscle function. For between-groups comparisons, the independent sample t-test was utilized.

Results: Sixty subjects (30 PFPS and 30 healthy) participated in this study. There were no significant differences between two groups with respect to demographic characteristics. No significant differences were observed between two groups regarding RF (P=0.07), VMO (P=0.38), VL (P=0.40) and VI (P=0.55) at rest. However, the rest thickness of VML (P=0.01) was significant between PFPS and healthy groups. No significant differences were found between two groups regarding RF (P=0.14), VML (P=0.68), VMO (P=0.11), VL (P=0.65), and VI (P=0.07) in contraction state. However, % rest-thickness normal were significant between groups for VML (P=0.03) and VMO (P=0.02) and were not significant for RF (P=0.56), VL (P=0.14) and VI (P=0.08).

Conclusion: In all parts of the quadriceps, % rest-thickness normal, as an indicator of its function, have been decreased in patients with PFPS. In patients with PFPF, ultrasonography should be cautiously used for muscle thickness comparisons.