National Physical Therapy Examination (NPTE) Practice Exam

A patient with knee extension at 18º will have hyperextension prevented by which factor?

1. Popliteal ligament

2. ACL

3. Quads to HS strength ratio of 6:1

4. Quads to HS strength ratio of 2:1

The correct answer is: Quads to HS strength ratio of 6:1

Knee hyperextension is typically prevented by the balance between the strength of the quadriceps and the hamstrings. The muscular strength ratios reflect the ability of these muscle groups to control the knee position. In this scenario, a quadriceps to hamstring strength ratio of 6:1 indicates that the quadriceps are significantly stronger than the hamstrings. This strong ratio means that the quadriceps can effectively stabilize the knee joint during extension and prevent excessive hyperextension. The quadriceps primarily function to extend the knee, and with a robust strength in this muscle group, they can counteract any tendency towards hyperextension that might occur if the knee were to flex beyond its normal limits. A lower strength ratio, such as 2:1, would suggest that the hamstrings are more capable of controlling extension, potentially allowing for some hyperextension to occur. The other options also represent anatomical structures and different physiological factors that contribute to limiting knee hyperextension, but they do not emphasize the specific significance of the strength ratio in providing such stability in this context. Thus, the strong quadriceps contribution is key in preventing hyperextension in this patient's case.