### When Bone Healing Goes Wrong

While bone healing is generally remarkably successful, sometimes the process doesn't proceed normally. Understanding these complications helps explain why proper fracture treatment is so important and what can be done when healing problems occur.

Delayed union occurs when bone healing proceeds normally but more slowly than expected. This can result from various factors including poor nutrition, smoking, infection, inadequate immobilization, or certain medications. Delayed union doesn't necessarily mean the bone won't heal, but it may require additional time and sometimes changes in treatment approach.

Nonunion represents a complete failure of the bone healing process. The fracture fails to heal even after an extended period, often requiring surgical intervention to achieve union. Nonunion can be caused by severe soft tissue damage, infection, poor blood supply, excessive movement at the fracture site, or systemic factors that impair healing. Some nonunions develop fibrous tissue between the bone fragments, while others show no evidence of any healing response.

Malunion occurs when the bone heals but in an improper position. This can result in deformity, loss of function, or accelerated arthritis in nearby joints. While some degree of malunion can be corrected through the natural remodeling process, significant deformities may require surgical correction.

Osteomyelitis, or bone infection, is a serious complication that can severely impair bone healing. Infection can occur at the time of injury, especially with open fractures, or develop later due to surgical treatment. Bone infections are particularly challenging to treat because the bone's limited blood supply makes it difficult for antibiotics to reach the infection site effectively.

Avascular necrosis can occur when the blood supply to a portion of bone is completely disrupted by the fracture. Without blood flow, that portion of bone dies and cannot participate in the healing process. This complication is most common in certain anatomical locations where blood supply is naturally limited, such as the femoral head or scaphoid bone.