Which of the following is an effect of traction?

Traction is a therapeutic technique commonly used in physical therapy to alleviate pain and improve function in the spine and other joints. One of the primary effects of traction is the reduction of disc protrusion and decreased pain. This occurs because traction generates a pulling force that can help separate the vertebrae, creating space in the intervertebral discs. This space allows for improved blood flow and nutrient exchange, potentially helping to reduce inflammation and alleviate pressure on surrounding nerves.

When traction is applied correctly, it can help alleviate symptoms associated with conditions like herniated discs by reducing the pressure on neural structures and allowing the discs to return to their more natural position. As a result, patients often experience decreased pain levels and improved mobility following traction therapy.

The other options do not represent typical effects of traction. Decreased muscle tension in the hands, improved flexibility in the knees, and increased joint stiffness are not direct intended outcomes of traction therapy. Thus, option C is the most accurate reflection of what traction can achieve in the therapeutic context.