malunion

Malunion is the healing of a fracture in an abnormal position after the fracture has united. It can involve angular deformity, rotational malalignment, shortening, or translation, and may result in functional impairment or ongoing pain. It is distinguished from delayed union and nonunion, which refer to incomplete healing or failure to heal, respectively.

Causes and risk factors include inadequate reduction, unstable fixation, persistent movement at the fracture site, severe or comminuted injuries, and issues with blood supply or infection. Patient factors such as smoking, diabetes, osteoporosis, and malnutrition increase risk. In children, some deformities may remodel over time, but significant malalignment can persist.

Clinical features often include deformity, pain, stiffness, limited function, or abnormal gait after a fracture has healed. Diagnostic evaluation relies on radiographs to assess the degree of angulation, rotation, shortening, and translation; computed tomography or magnetic resonance imaging may help quantify complex three-dimensional deformities.

Treatment is typically surgical for symptomatic malunions. Corrective osteotomy realigns the bone and restores length, using techniques such as closing-w wedge or opening-wedge osteotomies, with internal fixation (plates and screws or intramedullary devices) or external fixation (eg, Ilizarov). Bone grafting may be employed to fill defects. Nonoperative management may be considered for very mild deformities or when surgery is not feasible, but many symptomatic cases require correction plus rehabilitation.

Prognosis depends on the deformity’s severity and the chosen treatment. Successful correction can improve function and reduce pain, while residual malalignment may predispose to arthritis or activity limitation. Prevention focuses on accurate initial fracture reduction and stabilization, appropriate immobilization, and addressing risk factors such as smoking or nutritional deficiencies.