The experience of a healed fracture aching or throbbing when the temperature drops is a common phenomenon. This connection between old injuries and the weather is a scientifically recognized pattern. The pain is a genuine physical response rooted in the biology of how your body repairs itself and reacts to environmental shifts. The discomfort signals the site of the old injury, which remains a uniquely sensitive spot. Understanding this pain involves looking at how changes in atmospheric pressure, the nature of scar tissue, and the sensitivity of local nerves all interact.
Atmospheric Pressure and Internal Sensitivity
The sensation of pain in a healed bone often precedes a shift in weather, linked to changes in atmospheric weight. Cold fronts are typically heralded by a drop in barometric pressure. This decrease in external pressure allows soft tissues within your body, such as muscles, tendons, and fluids, to slightly expand.
The healed fracture site, characterized by dense, bony scar tissue, is far more rigid than the surrounding pliable tissues. When the less flexible fracture site is surrounded by expanding muscles and fluids, this creates a subtle mechanical stress.
The rigid bone callus is unable to expand at the same rate as the surrounding tissues, leading to increased pressure on the nerves embedded in and around the injury area. This microscopic pressure difference is enough to trigger a noticeable pain signal at the location of the old injury.
How Cold Affects Scar Tissue and Vascular Flow
The direct effect of cold temperature involves vasoconstriction, where blood vessels narrow to conserve core body heat. This reduction in blood vessel diameter decreases blood flow to the injury site, limiting the delivery of warmth, oxygen, and nutrients. Decreased circulation can also lead to the accumulation of inflammatory substances, contributing to heightened discomfort and stiffness.
The scar tissue, or bony callus, that formed to mend the fracture is structurally different from the original bone, often being denser and less elastic than healthy tissue. When exposed to cold, this already rigid scar tissue contracts and tightens more significantly than the surrounding healthy tissue. This differential contraction creates tension that pulls on adjacent structures, resulting in localized pain and stiffness at the fracture site.
Heightened Nerve Response at Injury Sites
The neurological component is a significant factor in why healed fractures are so sensitive to weather changes. During the initial fracture and the subsequent healing process, delicate nerve endings in the surrounding tissues are often damaged or severed. As the body lays down new bone and fibrous scar tissue, these regenerating nerve fibers can become trapped, embedded, or compressed within the dense, inflexible callus.
These newly encapsulated or partially damaged nerve endings are significantly more sensitive to external stimuli, including changes in temperature and pressure. The presence of cold easily excites these sensitized nerves, causing them to fire exaggerated pain signals—a form of neuropathic pain—back to the brain. This increased neurological sensitivity explains why the pain can feel sharp or intense. Keeping the area warm helps reduce the exaggerated nerve response by maintaining local circulation and limiting tissue contraction.