Compared with knee extension with the knee bent, patellofemoral compression forces during a straight leg raise are generally:

Compared with knee extension with the knee bent, patellofemoral compression forces during a straight leg raise are generally:

• A. Greater.
• B. The same.
• C. Unpredictable.
• D. Less.

Answer: (D)

Patellofemoral loading in open-chain knee movements depends largely on how much the knee is bent. When the knee is near full extension as in a straight leg raise, the contact between the patella and femur is reduced and the compressive force at the joint stays relatively low, even though the quadriceps are active to keep the leg straight. As the knee moves into flexion (which happens during knee extension tasks when starting from a bent knee), the patella sits deeper in the trochlear groove, the contact area increases, and the line of pull of the quadriceps creates a greater compressive component at the patellofemoral joint. This means the patellofemoral compression forces are generally higher with knee bending than with a straight leg raise. So, compared to knee extension with the knee bent, straight leg raise produces less patellofemoral compression.

Patellofemoral loading in open-chain knee movements depends largely on how much the knee is bent. When the knee is near full extension as in a straight leg raise, the contact between the patella and femur is reduced and the compressive force at the joint stays relatively low, even though the quadriceps are active to keep the leg straight. As the knee moves into flexion (which happens during knee extension tasks when starting from a bent knee), the patella sits deeper in the trochlear groove, the contact area increases, and the line of pull of the quadriceps creates a greater compressive component at the patellofemoral joint. This means the patellofemoral compression forces are generally higher with knee bending than with a straight leg raise. So, compared to knee extension with the knee bent, straight leg raise produces less patellofemoral compression.