National Physical Therapy Examination (NPTE) Practice Exam

After a distal radius fracture, which active thumb motion is likely affected if passive range of motion is normal?

1. Interphalangeal flexion

2. Interphalangeal extension

3. Metacarpophalangeal flexion

4. Metacarpophalangeal adduction

The correct answer is: Interphalangeal extension

After a distal radius fracture, it is common for patients to experience limitations in certain active motions of the thumb even if the passive range of motion remains normal. Specifically, interphalangeal extension is likely to be affected in this scenario. This can be attributed to the various factors associated with a distal radius fracture, such as pain, muscle weakness, swelling, and altered proprioception. Following the fracture, the ability to actively extend the interphalangeal joint of the thumb may be hindered due to these factors. Passive range of motion tests typically evaluate the joint's mobility irrespective of patient effort or motor control, so while the joints can still move passively through their full range, the individual may struggle to perform the extension actively due to discomfort or muscle balance issues. Understanding this relationship helps clinicians identify the specific areas where rehabilitation may focus, emphasizing strengthening and motor control to improve active extension function of the thumb, enhancing the patient's overall hand function post-fracture.