National Physical Therapy Examination (NPTE) Practice Exam

What is the most likely cause of the absence of quadriceps contraction in a patient with a comminuted femoral fracture and an external fixator?

1. A lesion in the femoral nerve

2. A contusion of the quadriceps muscle

3. An unstable fracture site

4. A lesion in the L4-L5 nerve roots

The correct answer is: A lesion in the femoral nerve

The most likely cause of the absence of quadriceps contraction in a patient with a comminuted femoral fracture and an external fixator is a lesion in the femoral nerve. The femoral nerve is responsible for innervating the quadriceps muscle, which is essential for knee extension. In the context of a comminuted femoral fracture, particularly when treated with an external fixator, there is a risk of nerve injury due to mechanical trauma, swelling, or positioning that can occur during the initial treatment. If the femoral nerve is compromised, the signal to initiate contraction in the quadriceps is disrupted, leading to paralysis or significant weakness in this muscle group. This is particularly critical given that the quadriceps is key not only for walking and running but also for stabilizing the knee and assisting in weight-bearing activities. If there is an absence of contraction, it usually correlates with nerve damage that directly affects muscle function. Other potential causes listed would not directly account for the loss of contraction in this particular muscle group. A contusion of the quadriceps muscle might result in pain and weakness, but it would not entirely eliminate contraction unless it created severe injury, which is less common. An unstable fracture site could lead to pain, which