Which factor is essential when evaluating a patient's range of motion?

When evaluating a patient's range of motion, comparing it to the opposite joint's range of motion is crucial. This method allows the clinician to establish a baseline of what is normal for that patient, as there is usually a degree of symmetry between paired joints in the body. For example, if one knee has a significantly reduced range of motion compared to the other, it may indicate a specific injury or pathology that needs further investigation.

This comparative approach helps determine whether the limitation in motion is unilateral or bilateral, guiding the clinician in developing appropriate treatment plans. It also supports identifying functional deficits that might not be apparent when only assessing the affected joint in isolation. Understanding the normal range on the opposite side can provide valuable insights into the extent of impairment and inform therapeutic goals.