Can ultrasound measurements of muscle thickness be used to measure the size of individual quadriceps muscles in people with patellofemoral pain?

OBJECTIVES

Selective atrophy of vastus medialis oblique (VMO) may be present in patellofemoral pain (PFP). This study investigated the validity of real-time ultrasound in measuring the thickness of each quadriceps muscle.

DESIGN

Cross sectional-Validity.

SETTING

University laboratory.

PARTICIPANTS

10 limbs, 5 people with unilateral PFP.

MAIN OUTCOME MEASURES

The thickness of VMO, vastus lateralis (VL), vastus intermedius (VI), rectus femoris (RF), and vastus medialis (VM) measured with ultrasound were compared to magnetic resonance imaging (MRI) muscle thickness measurements, using Pearson's (r), and compared to MRI muscle cross-sectional area (CSA) measurements, using Spearman's correlation coefficient (rho).

RESULTS

There was a good correlation between ultrasound and MRI measures of the thickness of each superficial quadriceps muscle VMO (r = 0.86), VM (r = 0.86), VL (r = 0.94), RF (r = 0.86), and a poor for VI (r = 0.37). Ultrasound measures had a good correlation to MRI muscle CSA measures for VL (rho = 0.83) and RF (rho = 0.88), moderate for VM (rho = 0.73), and poor for VMO (rho = 0.20), and VI (rho = 0.310).

CONCLUSION

Real-time ultrasound muscle thickness measurements are correlated to MRI measured thickness of superficial quadriceps muscles (VMO, VL, VL, and RF) in PFP.