What is the most significant contributor to joint stiffness?

Joint stiffness primarily arises from the structures that surround and support the joint, including the joint capsule, bones, and ligaments. The joint capsule is a fibrous tissue that encases the joint, and it plays a crucial role in maintaining joint stability while allowing for a range of motion. When considering the other structures, muscle tightness, tendons, and inflammation can impact joint mobility, but they do not usually encompass the overall stability and functional integrity of the joint as a whole to the same extent as the joint capsule and associated structures do.

The bones and ligaments work together with the joint capsule to provide stability while allowing for flexibility. Any changes in the integrity or condition of these components, whether due to aging, injury, or inflammatory conditions, can lead to increased stiffness. Therefore, the involvement of the joint capsule, bones, and ligaments as a cohesive unit is central to understanding the primary mechanisms that contribute to joint stiffness.