A muscle power deficit for PFPS is defined as:

A muscle power deficit for PFPS is defined as:

• A. LE muscle performance deficits in the hips and quads
• B. Pain only at night
• C. Pain in the ankle
• D. Tendon rupture

Answer: (A)

In PFPS, the defining feature is reduced ability of the lower-extremity muscles to generate power, particularly in the hip and knee. When hip abductors and external rotators, along with the quadriceps, lack sufficient strength and power, the knee can drift into valgus and internal rotation during activities like squatting, running, or stairs. This poor control increases patellofemoral joint contact and stress, leading to anterior knee pain that characterizes PFPS. So the best answer describes lower-extremity muscle performance deficits in the hips and quads—the muscles most responsible for stabilizing and guiding the patella during movement. The other choices describe symptoms or conditions that aren’t about muscle power deficits in PFPS: pain only at night isn’t specific to PFPS and doesn’t reflect muscle power failure; pain in the ankle points to a different area of pathology; tendon rupture is an acute, catastrophic injury with a distinct presentation.

In PFPS, the defining feature is reduced ability of the lower-extremity muscles to generate power, particularly in the hip and knee. When hip abductors and external rotators, along with the quadriceps, lack sufficient strength and power, the knee can drift into valgus and internal rotation during activities like squatting, running, or stairs. This poor control increases patellofemoral joint contact and stress, leading to anterior knee pain that characterizes PFPS. So the best answer describes lower-extremity muscle performance deficits in the hips and quads—the muscles most responsible for stabilizing and guiding the patella during movement.

The other choices describe symptoms or conditions that aren’t about muscle power deficits in PFPS: pain only at night isn’t specific to PFPS and doesn’t reflect muscle power failure; pain in the ankle points to a different area of pathology; tendon rupture is an acute, catastrophic injury with a distinct presentation.