What degree of curvature in the upper back defines kyphosis?

Kyphosis is defined by an increased curvature of the thoracic spine, often characterized by an exaggerated hunchback appearance. A curvature measurement of over 50° is commonly accepted as indicative of kyphosis. This degree of curvature can result in implications for posture and may cause physical discomfort or limitations in mobility. In clinical assessments, a curvature exceeding this threshold is significant enough to be categorized as abnormal.

Other measurement ranges, such as less than 30° or between 30° and 50°, typically fall within the normal variations of spinal curvature and do not represent the pathological condition of kyphosis. The option of exactly 90° also exceeds standard classifications and does not reflect the clinical understanding of kyphosis, which is primarily concerned with curvature degrees between 50° and above. Therefore, recognizing that kyphosis is defined by a curvature over 50° is essential for understanding its clinical relevance and management.