Lower Extremity Muscle Volume in Unilateral and Bilateral Patellofemoral Pain: A Cross-Sectional Exploratory Study Including Superficial and Deep Muscles Authors.

CONTEXT: Existing patellofemoral pain (PFP) literature has primarily focused on quadriceps muscle volume, with limited attention given to the lower limbs deep and superficial muscle volumes in individuals with unilateral and bilateral PFP. This research aims to fill this gap.

OBJECTIVE: To explore superficial and deep lower extremity muscle volume in women with unilateral and bilateral PFP compared to a normative database of pain-free women.

DESIGN: Cross-sectional study.

SETTING: University imaging research center.

PATIENTS OR OTHER PARTICIPANTS: Twenty women with PFP (10 unilateral and 10 bilateral) and 8 pain-free women.

MAIN OUTCOME MEASURE(S): We quantified lower extremity muscle volume via 3.0 Tesla magnetic resonance imaging. Two separate one-way analyses of variance were performed: (1) unilateral PFP (painful vs. non-painful limb) vs. pain-free control and (2) bilateral PFP (more painful vs. less painful limb) vs. pain-free control.

RESULTS: There were no differences in age and body mass index across groups (P >.05). Compared to pain-free women, both women with unilateral and bilateral PFP had bilaterally smaller volumes of the anterior (iliacus: P ≤ .0004, d = 2.12-2.65), medial (adductor brevis, adductor longus, gracilis, and pectineus: P ≤ .02, d = 1.25-2.24), posterior (obturator externus, obturator internus, and quadratus femoris: P < .05, d = 1.17-4.82), and lateral (gluteus minimus: P ≤ .03, d = 1.16-2.09) hip muscles, and knee extensors (rectus femoris: P ≤.003, d = 1.67-2.16) and flexors (biceps femoris: long and short head: P ≤ .01, d = 1.56-1.93).

CONCLUSIONS: Both women with unilateral and bilateral PFP 25 displayed decreased volume of multiple superficial and deep muscles of the bilateral hips and knees compared with pain-free women. Interventions should bilaterally target lower limb muscles when treating PFP, and hypertrophy exercises for specific muscles should be explored to enhance interventional choices.