A bone fracture describes a break or crack in the rigid structure of a bone. When trauma occurs, the body initiates a complex biological repair process designed to restore the bone’s integrity. For this natural process to be successful, the broken fragments must be held in precise alignment and kept stable. Failing to seek prompt medical evaluation and treatment disrupts this necessary alignment, converting a recoverable injury into a source of severe and lasting complications.
Structural Failure: Nonunion and Malunion
When a fractured bone is left without proper stabilization, the fundamental requirement for healing—immobile, correct alignment—is often not met. The instability at the fracture site can lead to two primary forms of structural failure that prevent the bone from regaining its original strength and shape.
The first type of failure is known as malunion, which occurs when the bone fragments successfully unite, but do so in an incorrect position or alignment. This misalignment results in a permanent deformity that changes the bone’s shape and length. A malunion can cause a visible disfigurement and significantly alter the normal biomechanics of the affected limb. Healing in a crooked or rotated position means that the forces experienced during daily activities are no longer distributed correctly across the bone and surrounding joints. This uneven distribution of stress often leads to chronic discomfort and strain on adjacent tendons and ligaments.
The second structural consequence is nonunion, which represents a complete failure of the bone to heal within the expected timeframe. When nonunion occurs, the body often creates a structure known as a pseudoarthrosis, essentially a false joint, at the fracture site. This false joint remains unstable, constantly moving and causing persistent pain and tenderness.
Nonunion results from a lack of biological stimulus or mechanical stability, which prevents the formation of a solid bony bridge between the fragments. In cases where blood supply to the bone fragments is insufficient, the nonunion is classified as atrophic, meaning there is no evidence of new bone growth attempting to cross the gap. Regardless of the type, a nonunion leaves the limb perpetually compromised, subjecting the individual to ongoing pain and functional limitations.
Acute Complications: Soft Tissue Damage and Infection
An untreated fracture presents an immediate threat beyond the bone itself due to the instability of the sharp, broken fragments. The unrestrained movement of these fragments can cause severe trauma to the surrounding soft tissues, including the vascular and nervous systems. A sharp bone end can lacerate nearby arteries, leading to significant blood loss and immediate loss of circulation to the distal limb. Similarly, an untreated fracture can cause damage to peripheral nerves, resulting in a loss of sensation or motor function below the injury site. This immediate vascular and neural damage can drastically compromise the limb’s viability, creating a time-sensitive medical emergency.
A particularly severe acute complication is acute compartment syndrome, which frequently follows high-energy fractures, especially in the lower leg. This condition arises when swelling or bleeding inside a closed, inelastic muscle compartment causes the internal tissue pressure to rise dangerously high. Because the thick layer of fascia surrounding the muscle cannot expand, the elevated pressure compresses the small blood vessels and nerves within the compartment.
This compression impedes capillary blood flow, leading to muscle and nerve ischemia—a lack of oxygenated blood. If the pressure is not surgically relieved, the muscle and nerve tissues will undergo irreversible necrosis, or tissue death. Untreated compartment syndrome can quickly lead to a permanent, debilitating deformity known as Volkmann’s contracture.
The death of muscle tissue releases toxins like myoglobin into the bloodstream, a process called rhabdomyolysis. These toxins travel to the kidneys, potentially causing acute renal failure, which is a life-threatening systemic complication. The immediate surgical release of the compartment, known as a fasciotomy, is the only treatment to prevent this chain of events.
Infection poses another profound acute and long-term danger, especially in open, or compound, fractures where the bone breaks through the skin. This breach allows bacteria from the environment to directly contaminate the bone tissue, initiating a severe infection known as osteomyelitis.
Once established, osteomyelitis is exceptionally difficult to eradicate because the bacteria can form a protective biofilm within the bone tissue. Treating this bone infection requires a prolonged course of antibiotics combined with extensive surgical debridement to remove the infected and necrotic bone. A persistent infection can necessitate eventual amputation of the limb.
Long-Term Functional Impairment
Even after the immediate danger of acute complications has passed, an untreated or poorly healed fracture can result in chronic conditions that permanently diminish the patient’s quality of life. One of the most common long-term consequences is the development of chronic pain, defined as pain persisting beyond the normal healing period. This persistent pain is not always purely mechanical. Chronic fracture pain often involves a complex biological shift, leading to central sensitization, where the nervous system becomes hypersensitive, causing pain signals to be amplified or misinterpreted.
Another major functional consequence is the accelerated development of post-traumatic arthritis (PTOA), a form of degenerative joint disease. This occurs most predictably when a fracture extends into a joint surface, known as an intra-articular fracture, and is left to heal improperly. A malunion that results in a joint surface incongruity causes uneven and excessive wear. This abnormal stress rapidly degrades the articular cartilage, leading to pain, stiffness, and reduced range of motion earlier than typical age-related arthritis.
Beyond pain and joint degeneration, structural failure directly results in permanent mobility limitations. Malunion can cause a noticeable limb length discrepancy, requiring the individual to expend more energy to walk or leading to secondary problems in the spine and hips. The chronic instability from a nonunion or the stiffness from prolonged disuse also limits the range of motion and overall strength of the affected limb. Without proper treatment and rehabilitation, muscles surrounding the injury site may atrophy, contributing to permanent weakness and instability that severely impacts the ability to perform daily activities.